project abolo

7/28/2019 Project Abolo

1/60

CHAPTER ONE

1.0 INTRODUCTION

1.1Background

The cost of fuel production is very expensive that is why product accountability is very

much important to every fuel handling establishment. It also important to ensure that

safety standards are upheld so as to protect the product, properties and human resource

(personnel) which has been engaged to render essential services. There is several oil

companies in the world and each of them have their peculiar missions, objective and

targets. Basically, they are categorized into two (2) groups, thus; downstream and

upstream oil sectors. The focus of the downstream sector is to ensure that petroleum

product is accessible at the retail point; here it is made possible by limited liability

companies privately owned by individuals/groups of investors such as bulk oil

distributors like fuel trade, oil channel, first deep water, trafigura, Cirus, to mention a

few through government established institutions like the Tema Oil Refinery (TOR),

Ghana National Petroleum Company Limited (GNPC) and Bulk OIL Storage and

Transportation Company Limited (BOST). TORs core mandate is to procure crude oil

and refine, GNPC also does explorations as well as procurement of crude in large

quantities whiles BOST focuses on strategic fuel reserves, including logistics for

effective storage and transportation of petroleum product.

The upstream is basically, companies such as Tullow oil and FPSO whose main

engagement is to drill and find oil in large quantities for either export or for domestic

consumption. The upstream operations are done offshore (deep seas) where the drilling

equipment has been installed; and staff (engineers and technician) normally go there by

either helicopter/chopper or by boat. Their activities are of great importance since it

Josiah K. Attah, BENG (Hons) Regent Ghana 1


2/60

generates a lot of revenue for government to embark on developmental projects as there

is readily market demand for fuel worldwide.

Much as their work is appreciated, it is important also that products which are drilled

from the oil fields are accounted for. It has been established that the product from FPSO

is not properly or accurately measured to ascertain the actual quantities before they are

dispatched to the world market.

FPSO, an upstream player in the industry has failed in this direction and it is absolutely

unacceptable to allow these challenges to persist in this day and age of technological

regime.

As engineering requires that existing systems are improved to enhance productivity,

efficiency and effectiveness, I have been motivated by the issues confronting FPSO in

respect of product measurement and wish to design a metering system to curtail the

problems, it will also ensure that the vessels are filled to the recommended capacities

(quantities) whiles putting safety on the top indentation of operations.

1.2 Statement of the Problem

FPSO drills crude oil in commercial quantity in Ghana for onward exportation to the oil

market through GNPC. The mode of measurement is inflicting product loss on the

economy since the mode of obtaining true quantity of product released into vessels is

not just outmoded, but also not safe; this as resulted in loss of revenue to the state.

The bulk of the oil vessels have been calibrated, but need level surface to obtain

perfection in measuring; a system which is a challenge on sea due to unevenness surface

nature of the sea the vessels berth to receive product into them.



3/60

The mode of ascertaining the product quantity released from the field is mainly the use

of measuring bars/level indicators which more often than not ends up resulting in

inaccuracies.

Finally, it is not safe for this mode of operation to continue because product spillage can

occur and this would endanger aqua culture and pollute the sea as a whole.

1.3 Objectives

The main objective of this project is to highlight the enormous benefit of the

implementation of the use of oil volume metering system which is to be designed as the

main source of instrument in the determination of product quantity instead of the

ancient existing ways of measurements and discharge of crude oil where the monitoring

leaves much to be desired and consequently human factors come into play.

Furthermore, to highlight the effectiveness of this monitoring system of which huge

savings is achieved for FPSO in particular and the nation as a whole.

The system to be implemented is to allow the operators to effectively and efficiently

monitor the product flow rate and the level in the vessel /tanker. It will enable the

operator to plan adequately and also to curtail the risk of crude oil spillage to the barest

minimum whiles ensuring that sanity and fairness prevails in the oil industry.

1.4Scope of study

This project when completed will minimize the issue of over delivery/under delivery of

petroleum products produced by both upstream and downstream petroleum sector.



4/60

It will also enhance the product accountability to optimize the proceeds of the oil

emanating from the oil fields or product being delivered to the market by the oil

marketing companies as well as refineries.

Metering systems would be installed at the source from where the product originates. It

can be on the pipelines, vessels, barges, tankers etc. to monitor, indicate and regulate the

volume depending on the calibration of the system.

1.5 Significance of Study

The significance of this project is to enhance the process of loading vessels at FPSO oil

fields in respect of monitoring and controlling product levels in vessels to avoid over

delivery/under delivery and also in the avoidance of spillage which will affect nature

adversely.

This metering system is very safe and conducive to work with since it is not risky to

adopt, secondly, it will eliminate the incidence of accident in the cause of determining

levels and human errors.

Finally, it will improve revenue generation and reduce overhead cost of crude delivery

to the world market.

1.6 Limitations of the study

This project when completed is to be used for the metering of fluid such as kerosene,

gasoline, gas oil, premix fuel, fuel oil, aviation turbine kerosene, liquefied petroleum

gas, water, crude oil etc.

It is highly sensitive equipment which is designed so as not to exceed the required

temperature, pressure and velocity. For this reason it will encounter challenges when it

is applied for bitumen or semi-liquid substances.



5/60

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 Introduction

The determination of the quantity of a fluid, either a liquid, vapour, or gas, that passes

through a pipe, duct, or open channel. Flow may be expressed as a rate of volumetric

flow (such as litres per second, gallons per minute, cubic meters per second, cubic feet

per minute), mass rate of flow (such as kilograms per second, pounds per hour), or in

terms of a total volume or mass flow (integrated rate of flow for a given period of time).

Measurement is accomplished by a variety of means, depending upon the quantities,

flow rates, and types of fluids involved. Many industrial process flow measurements

consist of a combination of two devices: a primary device that is placed in intimate

contact with the fluid and generates a signal, and a secondary device that translates this

signal into a motion or a secondary signal for the indicating, recording, controlling, or

totalizing the flow. Other devices indicate or totalize the flow directly through the

interaction of the flowing fluid and the measuring device that is placed directly or

indirectly in contact with the fluid stream . [1]

2.2 Flow Metering System

There are numerous types of flow metering system. The most common types of fluid

metering systems are:

1. Velocity flow meter

2. Differential pressure flow meters

3. Positive displacement flow meter

4. Mass flow meters

5. Open channel flow meters



6/60

2.2.1 Velocity Flow Meter

These instruments operate linearly with respect to the volume flow rate. Because there

is no square-root relationship (as with differential pressure devices), their range ability

is greater. Velocity meters have minimum sensitivity to viscosity changes when used at

Reynolds numbers above 10,000. Most velocity-type meter housings are equipped with

flanges or fittings to permit them to be connected directly into pipelines. [2]

Figure 2.1 shows a turbine flow meter that consists of a multiple-bladed, free spinning

and permeable metal rotor housed in a non-magnetic stainless steel body. In operation,

the rotating blades generate a frequency signal proportional to the liquid flow rates,

which is sensed by the magnetic pickup and transferred to a readout indicator.

Figure 2.1 Velocity Flow Meter

2.2.2Differential Pressure Flow Meter

In a differential pressure flow meter the flow is calculated by measuring the pressure

drop over an obstruction inserted in the flow. The differential pressure flow meter is

based on the Bernoullis Equation, where the pressure drop and the further measured

signal is a function of the square of the flow speed. [3]

http://www.engineeringtoolbox.com/bernouilli-equation-d_183.htmlhttp://www.engineeringtoolbox.com/bernouilli-equation-d_183.htmlhttp://www.engineeringtoolbox.com/bernouilli-equation-d_183.html


7/60

2.2.3 Positive-Displacement Meter

Operation of the positive displacement meter consists of separating liquids into

accurately measured increments and moving them on. Each segment is counted by a

connecting register. Because every increment represents a discrete volume, positive-

displacement units are popular for automatic batching and accounting applications.

Positive-displacement meter is a good choice for measuring the flows of viscous liquids

or for use where a simple mechanical meter system is required.

Fiqure 2.2 shows an oscillating piston meter that operates on a magnetic drive principle

so that liquid will not come in contact with parts. A partition plates between inlet and

outlet ports forces incoming liquid to flow around a cylindrical measuring chamber and

through the outlet port. The motion of the oscillating unit is transferred to a magnetic

assembly in the measuring chamber, which is coupled to a follower magnet on the

outside of the chamber wall.

Figure 2.2 Rotary-Piston Meter



8/60

2.2.4 Mass Flow Meter

The continuous need for an accurate flow measurement in mass-related processes

(chemical reactions, heat transfer, etc.) has resulted in the development of mass flow

meters. Various designs are available, but the most commonly used type for liquid flow

applications is the Coriolis meter. Its operation is based on the natural phenomenon

called the Coriolis force, hence the name.

Coriolis effect is a deflection of moving objects when they are viewed in a rotating

reference frame. In a reference frame with clockwise rotation, the deflection is to the

left of the motion of the object; in one with counter-clockwise rotation, the deflection is

to the right.

The Coriolis effect is caused by the rotation of the Earth and the inertia of the mass

experiencing the effect. Newton's laws of motion govern the motion of an object in a

(non-accelerating)inertial frame of reference. When Newton's laws are transformed to a

rotating frame of reference, the Coriolis and centrifugal forces appear. Both forces are

proportional to the mass of the object. The Coriolis force is proportional to the rotation

rate and the centrifugal force is proportional to its square. The Coriolis force acts in a

direction perpendicular to the rotation axis and to the velocity of the body in the rotating

frame and is proportional to the object's speed in the rotating frame. The centrifugal

force acts outwards in the radial direction and is proportional to the distance of the body

from the axis of the rotating frame. These additional forces are termed either inertial

forces, fictitious forces or pseudo forces. They allow the application of simple

Newtonian laws to a rotating system. They are correction factors that do not exist in a

true non-accelerating "inertial" system.

Perhaps the most commonly encountered rotating reference frame is the Earth. Because

the Earth completes only one rotation per day, the Coriolis force is quite small, and its

http://en.wikipedia.org/wiki/Rotating_reference_framehttp://en.wikipedia.org/wiki/Rotating_reference_framehttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Inertiahttp://en.wikipedia.org/wiki/Newton's_laws_of_motionhttp://en.wikipedia.org/wiki/Inertial_frame_of_referencehttp://en.wikipedia.org/wiki/Inertial_frame_of_referencehttp://en.wikipedia.org/wiki/Centrifugal_force_(rotating_reference_frame)http://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Fictitious_forcehttp://en.wikipedia.org/wiki/Rotating_reference_framehttp://en.wikipedia.org/wiki/Rotating_reference_framehttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Inertiahttp://en.wikipedia.org/wiki/Newton's_laws_of_motionhttp://en.wikipedia.org/wiki/Inertial_frame_of_referencehttp://en.wikipedia.org/wiki/Centrifugal_force_(rotating_reference_frame)http://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Fictitious_force


9/60

effects generally become noticeable only for motions occurring over large distances and

long periods of time, such as large-scale movement of air in the atmosphere or water in

the ocean. Such motions are constrained by the 2-dimensional surface of the earth, so

only the horizontal component of the Coriolis force is generally important.

This force causes moving objects on the surface of the Earth to appear to veer to the

right in the northern hemisphere, and to the left in the southern. Rather than flowing

directly from areas of high pressure to low pressure, as they would on a non-rotating

planet, winds and currents tend to flow to the right of this direction north of the equator,

and to the left of this direction south of it. This effect is responsible for the rotation of

large cyclones.[4]

A practical application of the Coriolis effect is the mass flow meter, an instrument that

measures the mass flow rate and density of a fluid flowing through a tube. The

operating principle involves inducing a vibration of the tube through which the fluid

passes. The vibration, though it is not completely circular, provides the rotating

reference frame which gives rise to the Coriolis effect. While specific methods vary

according to the design of the flow meter, sensors monitor and analyze changes in

frequency, phase shift, and amplitude of the vibrating flow tubes. The changes observed

represent the mass flow rate and density of the fluid . [5]

2.2.5Open Channel Flow Meter

The "open channel" refers to any conduit in which liquid flows with a free surface.

Included are tunnels, non-pressurized sewers, partially filled pipes, canals, streams, and

rivers. Of the many techniques available for monitoring open-channel flows, depth-

related methods are the most common. These techniques presume that the instantaneous

flow rate may be determined from a measurement of the water depth, or head. Weirs

http://en.wikipedia.org/wiki/Northern_hemispherehttp://en.wikipedia.org/wiki/Northern_hemispherehttp://en.wikipedia.org/wiki/Southern_hemispherehttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Cyclone#Structurehttp://en.wikipedia.org/wiki/Mass_flow_meterhttp://en.wikipedia.org/wiki/Mass_flow_ratehttp://en.wikipedia.org/wiki/Mass_flow_ratehttp://en.wikipedia.org/wiki/Mass_flow_ratehttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Northern_hemispherehttp://en.wikipedia.org/wiki/Southern_hemispherehttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Cyclone#Structurehttp://en.wikipedia.org/wiki/Mass_flow_meterhttp://en.wikipedia.org/wiki/Mass_flow_ratehttp://en.wikipedia.org/wiki/Density


10/60

and plumes are the oldest and most widely used primary devices for measuring open-

channel flow in hydraulics.

Weirs operate on the principle that an obstruction in a channel causes water to back up,

creating a high level (head) behind the barrier. The head is a function of flow velocity,

and, therefore, the flow rate through the device. Weirs consist of vertical plates with

sharp crests. The top of the plate can be straight or notched. Weirs are classified in

accordance with the shape of the notch. The basic types are V-notch, rectangular, and

trapezoidal. [6]

Meters normally consist of the following components to enable it function effectively

and efficiently:

1. Magnetic pickup

2. Rotor assembly

3. Rotor ball

4. Bushing

5. Thrust ball

6. Meter body

2.3Magnetic pickup

A magnetic pickup is essentially a coil wound around a permanently magnetized probe.

When discrete ferromagnetic objectssuch as gear teeth, turbine rotor blades, slotted

discs, or shafts with keywaysare passed through the probe's magnetic field, the flux

density is modulated. This induces AC voltages in the coil. One complete cycle of

voltage is generated for each object passed. If the objects are evenly spaced on a



11/60

rotating shaft, the total number of cycles is a measure of the total rotation, and the

frequency of the AC voltage is directly proportional to the rotational speed of the shaft.

(Output waveform is a function not only of rotational speed, but also of gear-tooth

dimensions and spacing, pole-piece diameter, and the air gap between the pickup and

the gear-tooth surface).

The pole-piece diameter should be less than or equal to both the gear width and the

dimension of the tooth's top (flat) surface; the space between adjacent teeth should be

approximately three times this diameter.[6]

Figure 2.3 below, shows a magnetic pickup used in conjunction with a 60-tooth gearto

measure the rpm of a rotating shaft. Such a gear is often selected because the output

frequency (in Hz) is numerically equal to rpma situation that allows frequency meters

to be employed without calibration. For very high rotational speeds, a smaller number

of teeth may be used.

A magnetic pickup may also be used as a timing or synchronization device for

example, in ignition timing of gasoline engines, angular positioning of rotating parts, or

stroboscopic triggering of mechanical motion. [7]



12/60

Figure 2.3 Magnetic Pickup

Figure 2.4 shows how a turbine flow meter can measure the volumetric flow of a fluid.

The fluid flow exerts a force on the turbine blades, causing the meter to rotate. In

properly designed flow meters, the output frequency produced by the magnetic pickup

is a linear function of the volumetric flow rate. Each output cycle therefore represents

the passage of a known volume of fluid, and the flow meter can be accordingly

calibrated in cycles per gallon or similar units. This rating is known as the "K factor" of

the flow meter. It will vary with the viscosity and flow rate, but is usually quite

predictable, with repeatability to within 0.1% in many units.

Figure 2.4 Turbine flow meter

2.3.1 Rotor Assembly



13/60

Rotor assembly basically consists of a shaft ad die- cast and both

components may be completely machined and assembled. The rationale

for the various rotor assembly options are unit volume and desired electric

motor efficiency, which relates to concentricity and the air gap between

the rotor and stator.[8]

2.3.2 Rotor ball

Rotor ball the rotor support is made possible by a ball or a sleeve bearing

in a shaft which in turn is held rigidly inside the meter.

2.3.3 Bushing

It is a type ofvibration isolator. It provides an interface between two parts, damping the

energy transmitted through the bushing. A common application is in flow meter rotor

suspension systems, where a bushing made ofrubber(or, more often, synthetic rubber

orpolyurethane) separates the faces of two metal objects while allowing a certain

amount of movement devoid of metal to metal contact to reduce friction.

Thesebushings often take the form of an annular cylinder of flexible material inside a

metallic casing or outer tube. They might also feature an internal crush tube which

protects the bushing from being crushed by the fixings which hold it onto a threaded

spigot. Many different types of bushing designs exist. An important difference

compared with plain bearings is that the relative motion between the two connected

parts is accommodated by strain in the rubber, rather than by shear or friction at the

interface.

http://en.wikipedia.org/wiki/Vibration_isolationhttp://en.wikipedia.org/wiki/Suspension_(vehicle)http://en.wikipedia.org/wiki/Suspension_(vehicle)http://en.wikipedia.org/wiki/Rubberhttp://en.wikipedia.org/wiki/Synthetic_rubberhttp://en.wikipedia.org/wiki/Polyurethanehttp://en.wikipedia.org/wiki/Spigothttp://en.wikipedia.org/wiki/Plain_bearinghttp://en.wikipedia.org/wiki/Vibration_isolationhttp://en.wikipedia.org/wiki/Suspension_(vehicle)http://en.wikipedia.org/wiki/Suspension_(vehicle)http://en.wikipedia.org/wiki/Rubberhttp://en.wikipedia.org/wiki/Synthetic_rubberhttp://en.wikipedia.org/wiki/Polyurethanehttp://en.wikipedia.org/wiki/Spigothttp://en.wikipedia.org/wiki/Plain_bearing


14/60

Figure 2.5 Mechanism of a flow meter

2.4 Manual flow meter

This type of flow meter in (fig 2.6) can also be employed to measure product quantity

into tanks, vessels, barges, oil tankers etc. but has limitations. It is normally applied in a

closed loop system to avoid air getting trapped in the metering system but its main

disadvantage is that when it is applied in a pump station or vibration area it

malfunctions.

Figure 2.6 Manual flow meter



15/60

2.5 Design & Construction Variations

Most industrial turbine flow meters are manufactured from austenitic stainless steel

whereas turbine meters intended for municipal water service are made of bronze or cast

iron. The rotor and bearing materials are selected to match the process fluid and the

service. Rotors are often made from stainless steel, and bearings of graphite, tungsten

carbide, ceramics or sapphire combined with tungsten carbide. In all cases, bearings and

shafts are designed to provide minimum friction and maximum resistance to wear.

Some corrosion-resistant designs are made from plastic materials such as PVC.

Small turbine meters often are called barstock turbines because in sizes of 1.905 to

7.62cm. They are machined from stainless steel hexagonal barstock. The turbine is

suspended by a bearing between two hanger assemblies that also serve to condition the

flow. This design is suited for high operating pressures (up to 333bars).

Similar to a pitot tube differential pressure flow meter, the insertion turbine meter is a

point-velocity device. It is designed to be inserted into either a liquid or a gas line to a

depth at which the small-diameter rotor reads the average velocity in the line. Because

of their sensitivity to the velocity profile of the flowing stream, they are profiled at

several points across the flow path.

Insertion turbine meters can be designed for gas applications (small, lightweight rotor)

or for liquid (larger rotor, water-lubricated bearings). They are often used in large

diameter pipelines where it would be cost-prohibitive to install a full size meter. They

can be hot-tapped into existing pipelines (15.24cm or larger) through a valving system

without shutting down the process. Typical accuracy of an insertion turbine meter is 1%

FS, and the minimum flow velocity is about 0.061m/sec.[9]

2.6 Past modes of measuring petroleum product



16/60

In the past, various forms were employed in the determination of fluid volume in tanks

and vessels. Some of the modes were the use of measuring tapes; with this process, the

operator has to climb the tank, assume the product level and apply product paste. The

dipping point of the storage tank is located and the tape is lowered into the tank and

until it touches the bottom or datum plate where it is rewound back for the actual level

of the product.

After, the dipping process is completed; a calibration table is referred to for the height to

be converted into actual volume of product in the tank. This process is very

cumbersome since there can be variations in dipping as well as reading of the volume.

The other problem is that when the calibrations of the tanks are not properly done

wrong result can be obtained. Since one deals with expensive product like crude oil/

petroleum products, accuracy is required in the day -to- day operations.

Safety is another important area of concern in that, with the process of climbing to the

top of the tanks and vessels if care is not taken one could slip and fall from a height and

this can cause injuries/death to innocent operators/staff no matter how careful one is.

Finally, the issue of spillage also comes up since actual volume of product entering

tanks is not known immediately.

2.7 Oil Volume Metering System

Oil Volume metering System is used for measuring product quantity entering or leaving

a fuel depot or oil tankers of vessels. Completion of this project will capture other

parameters of great importance. In the oil industry, density and temperature are very

essential since it aids in the determination of actual product quantity.



17/60

CHAPTER THREE

3.0 METHODOLOGY

3.1 Introduction

The project ensures that product flowing into vessels/tankers is accurately measured by

a volumetric meter designed to actualize that achievement. Several oil meters are in

existence but this one is unique since it will address most of the critical volumetric

issues in respect of the above mentioned and it will also put to rest issues confronting

the oil industry for example, loss of revenue. It will also highlight the components

which would be employed so as to bring this project into fruition.

3.2 Block Diagrams

The Electromagnetic meter consists of a non-ferromagnetic tube wrapped with a

magnetic coil. Electrodes in the tubes inner isolated surface are in contact with the

liquid (must be conductive) that flows through the tube. The coils around the pipe

generate a magnetic field within the tube. The magnetic field inducts a voltage in the

liquid, which is proportional to the speed of the liquid in the tube. This voltage is



18/60

measured via the electrodes. As the measured voltage is very low, precise low-noise

signal conditioning is required.

Coriolis meter is a popular Flow meter that directly measures mass flow rate. The pipe

through which the fluid is flowing is made to oscillate at a particular resonant frequency

by forcing a strong magnetic field on the pipe. When the fluid starts flowing through the

pipe, it is subject to Coriolis force. The oscillatory motion of the pipe superimposes on

the linear motion of the fluid exerting twisting forces on the pipe. This twisting is due to

Coriolis acceleration acting in opposite directions on either side of the pipe and the

fluids resistance to the vertical motion. Sensor electrodes are placed on both the inlet

and outlet sides which pick up the time difference caused by this motion. This phase

shift due to the twisting forces is a direct measurement of mass flow rate.

The field coils can be excited with AC or DC or Pulsed DC field. Each method has its

own pros and cons and depending on the particular application requirements, one

method may be favourable over the other.



19/60

Figure 3.1 The Block Diagram of Oil Volume Metering System

3.3 Digital Driver

The operation of a mass flow meter is dependent upon the proper oscillation of the flow

tube. This is controlled by the drive signal(s) generated by the transmitter. The

oscillation of the flow tube (as indicated by the sensor signals) is typically sinusoidal

and hence characterized in terms of frequency, phase and amplitude. The drive signal is

also often sinusoidal, or at least a regular waveform (e.g. square wave) for which similar



20/60

attributes can be defined: the frequency, phase (relative to the sensor signal) and

amplitude of the drive signal need to be determined and generated for optimal operation

of the flow tube. A commonly-used criterion for optimal operation is that the flow tube

should oscillate at its natural frequency of vibration, at fixed amplitude. As

measurement algorithms assume constant amplitude of oscillation over the calculation

interval (typically 5 500ms), amplitude stability is relevant for measurement quality.

For oscillation at the natural frequency, it is necessary for the driving force to be 90 out

of phase with the motion of vibration. Conveniently, the most commonly used sensor,

based on an electromagnetic coil, measures velocity, hence the sensor signal is 90 out

of phase with the motion of the flow tube. Thus an optimal drive signal has the same

frequency of oscillation and phase as the sensor signal, with drive amplitude selected to

maintain constant sensor amplitude.

Matching the drive output to the exact phase of the sensor signal is challenging. With

small levels of phase offset, and with benign process conditions, the consequences are

small the drive signal power requirement increases. With more significant phase offset

between driver and sensor, the flow tube oscillation becomes forced rather than natural.

The drive energy requirement also become significantly higher and the drive frequency

can drift away from its natural value. Finally, with large phase offset the meter may

cease vibrating entirely (stalling), or begin to oscillate in another mode of vibration,

typically at a frequency where the phase offset between driver and sensor is closer to an

integral multiple of 360 degrees. Analogous issues are seen in power electronics design:

for sinusoidal inputs and outputs, digital delay in the control circuitry can lead to

inefficiencies.

The most common technique for generating a drive signal has been analogue positive

feedback, whereby the sensor signal (containing the desired frequency and phase



21/60

characteristics) is multiplied by a drive gain factor (either by analogue or digital means).

The drive gain required to maintain the desired amplitude of oscillation is proportional

to the mechanical damping on the flow tube.

Assuming negligible delay in the analogue feedback circuitry, this approach ensures

phase matching between sensor input and drive output. Positive feedback is easy to

implement, but it provides only partial control of the drive waveform, and cannot

prevent unwanted components in the sensor signal (e.g. other modes of vibration) from

being fed back into the drive signal. In particular, in the presence of two-phase flow,

drive systems based on analogue feedback are prone to stalling. The mechanical

damping on the flow tube rises by two orders of magnitude with two-phase flow, and

this damping varies rapidly. Most analogue drive systems are unable to track and

respond to damping under two-phase flow. Some designs have a maximum drive gain

which, if exceeded by the damping, leads to catastrophic collapse in oscillation. High

and variable damping leads to low and variable sensor amplitudes, and it is possible to

lose track of the sensor signals, especially if they are contaminated with other modes of

vibration.

An all-digital drive system avoids many of the pitfalls associated with analogue positive

feedback. The alternative approach presented in this paper is drive waveform synthesis,

whereby the transmitter generates the drive waveform digitally. For example a pure sine

wave or square wave, with the required amplitude, frequency and phase characteristics,

in order to provide a highly adaptable and precise drive signals. This has several

advantages over positive feedback, including full control over the drive waveform, and

an ability to maintain operation even in two-phase flow, but has the challenge to match

the phase of the sensor signal in real time.



22/60

The dynamic response of the meter can be measured by the time required to

indicate a step changes in flow. This transmitter has demonstrated a response

time of 4ms, between 1 and 2 orders of magnitude faster than other Coriolis

meters. This has found industrial application in, for example, short proving runs

for custody transfer applications, and filling applications.

The two-phase problem has been transformed into a useful two-phase

measurement capability, with numerous industrial applications, particularly in

the oil and gas sector.[10]

Figure 3.2 Circuit of an Electronic Driver

The main effect is a dramatic rise in the flow tube damping, perhaps by two orders of

magnitude. Mechanical energy is lost in the interactions between compressible bubbles,



23/60

fluid and flow tube walls, and the drive energy required to maintain oscillation rises

sharply. Not only does the damping rise, but it varies rapidly, due to the chaotic nature

of the interactions. Similarly, the frequency and amplitude of oscillation exhibit much

greater variation than for single phase. The consequences for drive output are as

follows:

Drive energy saturation. For any intrinsically safe flow tube, there is an absolute limit

on the energy supplied to the driver(s) for example 100mA. The default amplitude of

oscillation may not be sustainable.

Some positive feedback drives cannot exceed a maximum drive gain limit e.g. due to

amplifier saturation. This means there is a maximum multiplier between the sensor

amplitude in and the drive signal out. Suppose this limit is reached, and the flow tube

damping raises again due to yet more gas in the two-phase flow mix. A further rise in

drive current to compensate for the increased damping is not possible, due to drive

saturation. As a consequence, the sensor amplitude starts to reduce, but this in turn

leads, again because of drive saturation, to a drop in the drive signal output; the end

result is a catastrophic collapse in oscillation amplitude. The rapid changes in damping,

amplitude, frequency and phase on the sensor signal ensures fast and accurate tracking

by the transmitter in order to generate an appropriate drive signal. If the drive control

update rate is simply too slow, the flow tube may stall due to inattention.

Meter transmitter technology is to provide improved measurement performance and

robustness. Several features provide improved flow tube control in the face of two-

phase flow, including:

Measurement and control updates every half drive cycle (typically every 6ms)

Rapid dynamic response



24/60

Synthesis of a pure sine wave with the required amplitude, frequency and phase

characteristics, providing a highly adaptable and precise drive signal.

A non-linear amplitude control algorithm providing stable oscillation.

Selection of a sustainable set-point for the amplitude of oscillation during two-

phase flow.

The ability to generate counter-phase signals or so-called negative gain. [11]

3.4 Analogue to Digital Converter

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device that

converts a continuous quantity to a discrete timedigital representation. An ADC may

also provide an isolated measurement. The reverse operation is performed by a digital-

to-analog converter(DAC).

Typically, an ADC is an electronic device that converts an input analog voltage or

current to a digital number proportional to the magnitude of the voltage or current.

However, some non-electronic or only partially electronic devices, such as rotary

encoders, can also be considered ADCs. The digital output may use different coding

schemes. Typically the digital output will be a two's complement binary number that is

proportional to the input, but there are other possibilities.

Figure 3.3 below indicates an ADC converter in flow metering system for the project.

The voltage output from each sensor and bridge board set is sent to its own Master-

Touch microprocessor board for accurate linearization of the flow rate signal. The

linearised output signals from the multiple sensors in the probe are then averaged by a

http://en.wikipedia.org/wiki/Continuous_signalhttp://en.wikipedia.org/wiki/Continuous_signalhttp://en.wikipedia.org/wiki/Discrete_signalhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Rotary_encoderhttp://en.wikipedia.org/wiki/Rotary_encoderhttp://en.wikipedia.org/wiki/Two's_complementhttp://en.wikipedia.org/wiki/Continuous_signalhttp://en.wikipedia.org/wiki/Discrete_signalhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/Digital-to-analog_converterhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Rotary_encoderhttp://en.wikipedia.org/wiki/Rotary_encoderhttp://en.wikipedia.org/wiki/Two's_complement


25/60

summer/average module. Typically, the probe assemblys averaged output signal is

transmitted to the remote Flow Meter System control panel for grand averaging with the

signals from other probe assemblies. However, flow transmitter assemblies may be

specified with either one average output signal and/or individual signals to allow

individual sensor readings at the Flow metering System control panel.

Individual sensor and bridge board sets may be periodically tested at the probe location

to verify performance. If one or more sets are not functioning as required, they may be

removed from the probe signal average by removing the sensor input wire and turning

off a DIP switch on the averager board without affecting overall Flow Metering

Systems operation.

The individual sensor and bridge board sets are field replaceable without complete

probe disassembly. [11]



26/60

Figure 3.3 Analogue to Digital Converter installed in flow meter

3.5 Digital to Analogue Converter

A DAC converts an abstract finite-precision number (usually a fixed-pointbinary

number) into a physical quantity (e.g., a voltage or apressure). In particular, DACs are

often used to convert finite-precision time seriesdata to a continually varying physical

signal.

http://en.wikipedia.org/wiki/Abstract_objecthttp://en.wikipedia.org/wiki/Abstract_objecthttp://en.wikipedia.org/wiki/Fixed-point_arithmetichttp://en.wikipedia.org/wiki/Binary_numberhttp://en.wikipedia.org/wiki/Binary_numberhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Time_serieshttp://en.wikipedia.org/wiki/Time_serieshttp://en.wikipedia.org/wiki/Signal_(electronics)http://en.wikipedia.org/wiki/Abstract_objecthttp://en.wikipedia.org/wiki/Fixed-point_arithmetichttp://en.wikipedia.org/wiki/Binary_numberhttp://en.wikipedia.org/wiki/Binary_numberhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Time_serieshttp://en.wikipedia.org/wiki/Signal_(electronics)


27/60

A typical DAC converts the abstract numbers into a concrete sequence of impulses that

are then processed by a reconstruction filterusing some form ofinterpolationto fill in

data between the impulses. Other DAC methods (e.g., methods based on Delta-sigma

modulation) produce a pulse-density modulated signal that can then be filtered in a

similar way to produce a smoothly varying signal.

As per the NyquistShannon sampling theorem, a DAC can reconstruct the original

signal from the sampled data provided that its bandwidth meets certain requirements

(e.g., a baseband signal with bandwidth less than the Nyquist frequency). Digital

sampling introduces quantization error that manifests as low-level noise added to the

reconstructed signal. Instead of impulses, usually the sequences of numbers update the

analogue voltage at uniform sampling intervals. These numbers are written to the DAC,

typically with a clock signal that causes each number to be latched in sequence, at

which time the DAC output voltage changes rapidly from the previous value to the

value represented by the currently latched number. The effect of this is that the output

voltage is held in time at the current value until the next input number is latched

resulting in a piecewise constant or 'staircase' shaped output. This is equivalent to a

zero-order hold operation and has an effect on the frequency response of the

reconstructed signal.

The fact that DACs output is a sequence of piecewise constant values (known as zero-

order hold in sample data textbooks) or rectangular pulses causes multiple harmonics

above theNyquist frequency. Usually, these are removed with a low pass filteracting as

a reconstruction filter in applications that require it.

3.6 Processor

http://en.wikipedia.org/wiki/Dirac_delta_functionhttp://en.wikipedia.org/wiki/Reconstruction_filterhttp://en.wikipedia.org/wiki/Interpolationhttp://en.wikipedia.org/wiki/Interpolationhttp://en.wikipedia.org/wiki/Delta-sigma_modulationhttp://en.wikipedia.org/wiki/Delta-sigma_modulationhttp://en.wikipedia.org/wiki/Pulse-density_modulationhttp://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theoremhttp://en.wikipedia.org/wiki/Basebandhttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Nyquist_frequencyhttp://en.wikipedia.org/wiki/Quantization_errorhttp://en.wikipedia.org/wiki/Sampling_frequencyhttp://en.wikipedia.org/wiki/Sampling_frequencyhttp://en.wikipedia.org/wiki/Clock_signalhttp://en.wikipedia.org/wiki/Latch_(electronic)http://en.wikipedia.org/wiki/Piecewise_constanthttp://en.wikipedia.org/wiki/Piecewise_constanthttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Rectangular_functionhttp://en.wikipedia.org/wiki/Nyquist_frequencyhttp://en.wikipedia.org/wiki/Low_pass_filterhttp://en.wikipedia.org/wiki/Low_pass_filterhttp://en.wikipedia.org/wiki/Dirac_delta_functionhttp://en.wikipedia.org/wiki/Reconstruction_filterhttp://en.wikipedia.org/wiki/Interpolationhttp://en.wikipedia.org/wiki/Delta-sigma_modulationhttp://en.wikipedia.org/wiki/Delta-sigma_modulationhttp://en.wikipedia.org/wiki/Pulse-density_modulationhttp://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theoremhttp://en.wikipedia.org/wiki/Basebandhttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Nyquist_frequencyhttp://en.wikipedia.org/wiki/Quantization_errorhttp://en.wikipedia.org/wiki/Sampling_frequencyhttp://en.wikipedia.org/wiki/Clock_signalhttp://en.wikipedia.org/wiki/Latch_(electronic)http://en.wikipedia.org/wiki/Piecewise_constanthttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Zero-order_holdhttp://en.wikipedia.org/wiki/Rectangular_functionhttp://en.wikipedia.org/wiki/Nyquist_frequencyhttp://en.wikipedia.org/wiki/Low_pass_filter


28/60

A processor is the logic circuitry that responds to and processes the basic instructions

that drives a computer.

The term processor has generally replaced the term central processing unit (CPU). The

processor in a personal computer or embedded in small devices is often called a

microprocessor.

3.7 Fuel Sensors

A fuel sensor is a device for sensing the fluid. Typically a fuel sensor is the sensing

element used in a fuel meter, or flow logger, to record the volume of fluids. As is true

for all sensors, absolute accuracy of a measurement requires functionality for

calibration.

There are various kinds of fuel sensors and fuel meters, including some that have a vane

that is pushed by the fluid, and can drive a rotary potentiometer, or similar devices.

Other flow sensors are based on sensors which measure the transfer of heat caused by

the moving medium. This principle is common for micro sensors to measure fuel

quantity.

Fuel meters are related to devices called velocimeters that measure velocity of fluids

flowing through them. Laser-based interferometer is often used for air flow

measurement, but for liquids, it is easier to measure the flow. Another approach is

Doppler-based methods for flow measurement. Hall Effect sensors may also be used, on

a flapper valve, or vane, to sense the position of the vane, as displaced by fluid. [12]

Figure 3.4a and Figure 3.4b below indicates/illustrate the circuit diagram and typical

connections respectively.

http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212356,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci213867,00.htmlhttp://en.wikipedia.org/wiki/Rate_of_fluid_flowhttp://en.wikipedia.org/wiki/Rate_of_fluid_flowhttp://en.wikipedia.org/wiki/Sensorhttp://en.wikipedia.org/wiki/Flow_meterhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Calibrationhttp://en.wikipedia.org/w/index.php?title=Rotary_potentiometer&action=edit&redlink=1http://en.wikipedia.org/wiki/Microsensorhttp://en.wikipedia.org/wiki/Velocimetryhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Interferometryhttp://en.wikipedia.org/wiki/Interferometryhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Photoacoustic_Doppler_effecthttp://en.wikipedia.org/wiki/Hall_effect_sensorhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212356,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci213867,00.htmlhttp://en.wikipedia.org/wiki/Rate_of_fluid_flowhttp://en.wikipedia.org/wiki/Sensorhttp://en.wikipedia.org/wiki/Flow_meterhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Calibrationhttp://en.wikipedia.org/w/index.php?title=Rotary_potentiometer&action=edit&redlink=1http://en.wikipedia.org/wiki/Microsensorhttp://en.wikipedia.org/wiki/Velocimetryhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Interferometryhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Photoacoustic_Doppler_effecthttp://en.wikipedia.org/wiki/Hall_effect_sensor


29/60

Figure 3.4a Circuit Diagram of a sensor



30/60

Figure 3.4b Sensor Connected to Oil Volume Metering System



31/60

CHAPTER FOUR

4.0 SYSTEM DESIGN, DEVELOPMENT AND IMPLEMENTATION

4.1 IntroductionThis chapter discusses in detail the block diagram for the project; highlight the

important components including the main circuit diagram and its operation.

4.2 Circuit Diagram of the Oil Volume Metering System

Figure 4.1 on the next page indicates the circuit diagram and the various components

which can mitigate the issues of uncertainty in measuring fluid.



32/60

Figure 4.1 Schematic diagram of fuel metering system



33/60

4.3 Power Supply Unit

In every electronic unit or equipment it is necessary to get it connected a power supply

unit or batteries (dry cells) and so is the flow metering system. It is powered by a 3v 1

amp power supply. Since it is a DC voltage supply, an AC voltage was converted with

the utilization of rectifiers (diodes), step down transformer, filtration system

components and short circuit protection unit.

The regulated power supply is to provide the necessary dc voltage and current, with low

levels of ac ripple and with stability and regulation. There are various methods of

achieving a stable dc voltage from ac mains. The two methods are more commonly

used. These are used;

(i) a linear voltage regulator and

(ii)A switching mode regulator.

Several types of both linear and switching regulators are available in integrated circuit

(IC) form. By using the linear voltage regulator method, a regulated dual dc power

supply must be procured. [14]

Figure 4.2 below Indicates a Block diagram of rectification process.

Figure 4.2 Block Diagram of the Regulated Voltage DC Power Supply



34/60

Through combination of step down transformer, rectifier, filters and voltage regulators

together, a regulated dual voltage dc power supply circuit is obtained shown in

Figure 4.3.

This is the circuit, which gives regulated 1.2V to 15V supply. ICs LM 317T and LM

337T are used here as positive and negative regulators respectively.

The LM 317T regulator has internal feedback regulating mechanism with current

passing elements. It incorporates various protection circuits such as current limit (which

limits package power dissipation to 15 watts for the TO-220 package) and thermal

shutdown. Thus these two ICs form an independently adjustable bipolar power supply.

Capacitors, although not always necessary are sometimes used on the input and output

as indicated in figure 4.3. The output capacitors C7 and C8 acts basically as line filter to

improve transient response. The input capacitors C3 and C4 are used to prevent

unwanted oscillations when the regulator is some distance away from the power supply

filter such that the line has a significant inductance. D5 and D6 prevent short-circuit for

input and output terminals.

The TO-220 package easily provides one ampere each if the heat sinks are properly

mounted. Variable resistors VR1 and VR2 are adjusted for each regulator to give a

regulated output approximately between 1.2V to 15V. Capacitors C5 and C6 are used

to improve AC ripple voltage rejection. However, if a short-circuit occurs across the

regulator outputs, C5 and C6 can adjust the current in the terminals. The output can be

calculated by the formula:

)R

V1(V25.1V

1

1R0 += -----------------------------------------------------

4.1

different

d(max)L

V

PI = ---------------------------------------------------------4.2



35/60

Figure 4.3 Bridge rectifier



36/60

Table 4.1 Values of component required

Component Value

Resistors

R1, R2 330 , W, 5%

VR1, VR2 5K , Potentiometer

Capacitor

C1, C2 4700 F/25V, ELE

C3,C4 0.1 F/25V, CD

C5, C6 10 F/25V, ELE

C7, C8 1 F/35V, ELE

Diodes

D1, D2, D3, D4 1N 5402 diodes

D5, D6 1N 4007 diodes

ICs LM 317T, Adjustable positive voltage

regulator

IC1 LM 337T, Adjustable negative voltage

regulator

IC2

Miscellaneous

Transformer 220V AC Primary: to 18V-0-18V, 3A

Sec:

Meters (0-30)V DC Voltmeters

Switch ON/OFF switch

LEDs, Heat sinks, PCB, Knobs,

Solder, Wires, Sockets, Fuse etc:

Table 4.2 Characteristic of LM regulator



37/60

Parameter Conditions LM317/LM337 Units

Line Regulation TA = 25 C, 3V Vin Vout 40V 0.04 %/V

Load Regulation TA = 25 C, 10mA Iout Imax

Vout 5V 25.00 mV

Vout 5V 0.4 %

Thermal Regulation TA = 25 C, 20ms Pulse 0.07 %/WAdj: Pin Current 100.0 A

Reference Voltage 1.25 V

Temperature Stability Tmin Tj Tmax 1.00 %

Ripple Rejection Ratio Vout = 10V, F = 120Hz, Cadj =

10F

80.00 Db

Current Limit (Max) (VIN VOUT 15V) 1.00 A

Current Limit (Min) (VIN VOUT = 40V) 0.40 A

4.3.1 LM78xx Series Voltage Regulator

Choosing a linear regulator for an application involves more than looking for the part

with the lowest dropout voltage or lowest cost. Although IC manufacturers promote

regulators with very low dropout voltages, these are often the most expensive part in

their product line and not necessarily the best solution. By considering system

specifications such as minimum and maximum input voltage, load current and system

cost, a designer are able choose the best regulator for an application.

The three bipolar output structures found in most linear regulators has advantages, as

well as disadvantages and the reasons for using certain output stages in certain

situations are discussed. Throughout the project, design examples are provided to

illustrate the process of selecting the right output structure for a given set of system

conditions. [15]

The LM78XX monolithic 3-terminal positive voltage regulators employ internal

current-limiting, thermal shutdown and safe-area compensation, making them

essentially indestructible. If adequate heat sinking is provided, they can deliver over

1.0A output current. They are intended as fixed voltage regulators in a wide range of

applications including local (on-card) regulation for elimination of noise and



38/60

distribution problems associated with single-point regulation. In addition to use as fixed

voltage regulators, these devices can be used with external components to obtain

adjustable output voltages and currents. Considerable effort was expended to make the

entire series of regulators easy to use and minimize the number of external components.

It is not necessary to bypass the output, although this does improve transient response.

Input bypassing is needed only if the regulator is located far from the filter capacitor of

the power supply. The 5V, 12V, and 15V regulator options are available in the steel

TO-3 power package. The LM78XXC series is available in the TO-220 plastic power

package, and the LM340-5.0 is available in the SOT-223 package, as well as the

LM340-5.0 and LM340-12 in the surface-mount TO-263 package. The features of the

components are as follows;

Complete specifications at 1A load

Output voltage tolerances of 2% at Tj = 25C and 4%

over the temperature range (LM340A)

Line regulation of 0.01% of VOUT/V of VIN at 1A load (LM340A)

Load regulation of 0.3% of VOUT/A (LM340A)

Internal thermal overload protection

Internal short-circuit current limit

Output transistor safe area protection

P+ Product Enhancement tested [16]

4.3.2 Microcontroller

A microcontroller is a computer. All computers -- whether a personal desktop computer

or a large mainframe computer or a microcontroller they have several things in

common:

http://electronics.howstuffworks.com/pc.htmhttp://electronics.howstuffworks.com/question543.htmhttp://electronics.howstuffworks.com/pc.htmhttp://electronics.howstuffworks.com/question543.htm


39/60

All computers have a CPU (central processing unit) that executes programs. The

CPU in a machine executes a program that implements the Web browser that is

displaying this page.

The CPU loads the program from somewhere. On your desktop machine, the

browser program is loaded from the hard disk.

The computer has a RAM (random-access memory) where it can store

"variables."

The computer has an input and output devices so that it can communicate to

people. On your desktop machine, the keyboard and mouse are input devices

and the monitorandprinterare output devices. A hard disk is an I/O device -- it

handles both input and output.

The computer is a "general purpose computer" that can run a lot of programs.

Microcontrollers are "special purpose computers.

There are a number of other common characteristics that define microcontrollers. If a

computer matches a majority of these characteristics, then can be referred to as

"microcontroller":

Microcontrollers are "embedded" inside other device (often a consumer product)

so that they can control the features or actions of the product. Another name for

a microcontroller, therefore, is "embedded controller."

Microcontrollers are dedicated to one task and run one specific program. The

program is stored in ROM (read-only memory) and generally does not change.

Microcontrollers are often low-power devices. A desktop computer is almost

always plugged into a wall socket and might consume 50 watts of electricity. A

battery-operated microcontroller might consume 50 mill watts.

http://electronics.howstuffworks.com/microprocessor.htmhttp://electronics.howstuffworks.com/hard-disk.htmhttp://electronics.howstuffworks.com/ram.htmhttp://electronics.howstuffworks.com/keyboard.htmhttp://electronics.howstuffworks.com/mouse.htmhttp://electronics.howstuffworks.com/monitor.htmhttp://electronics.howstuffworks.com/monitor.htmhttp://electronics.howstuffworks.com/inkjet-printer.htmhttp://electronics.howstuffworks.com/inkjet-printer.htmhttp://electronics.howstuffworks.com/rom.htmhttp://electronics.howstuffworks.com/microprocessor.htmhttp://electronics.howstuffworks.com/hard-disk.htmhttp://electronics.howstuffworks.com/ram.htmhttp://electronics.howstuffworks.com/keyboard.htmhttp://electronics.howstuffworks.com/mouse.htmhttp://electronics.howstuffworks.com/monitor.htmhttp://electronics.howstuffworks.com/inkjet-printer.htmhttp://electronics.howstuffworks.com/rom.htm


40/60

A microcontroller has a dedicated input device and often (but not always) has a

small LED or LCD display for output. A microcontroller also takes input from

the device it is controlling and controls the device by sending signals to different

components in the device.

For example, the microcontroller inside a TV takes input from the remote control and

displays output on the TV screen. The controller controls the channel selector, the

speakersystem and certain adjustments on the picture tube electronics such as tint and

brightness. The engine controller in a car takes input from sensors such as the oxygen

and knock sensors and controls the fuel mix and spark plug timing. A microwave oven

controller takes input from a keypad, displays output on an LCD display and controls a

relay that turns the microwave generator on and off.

A microcontroller is often small and is low in cost. The components are selected

to minimize size and to be as inexpensive as possible.

The microcontroller controlling a car's engine, for example, has to work in temperature

extremes that a normal computer generally cannot handle. On the other hand, a

microcontroller embedded inside a VCR has not been ruggedized at all.

The actual processor used to implement a microcontroller can vary widely. For

example, the cell phone shown on Inside a Digital Cell Phone contains a Z-80

processor. The Z-80 is an 8-bit microprocessor developed in the 1970s and originally

used in home computers of the time. The Garmin GPS shown in How GPS Receivers

Work contains a low-power version of the Intel 80386, I am told. The 80386 was

originally used in desktop computers.

In many products, such as microwave ovens, the demand on the CPU is fairly low and

price is an important consideration. In these cases, manufacturers turn to dedicated

http://electronics.howstuffworks.com/inside-rc.htmhttp://electronics.howstuffworks.com/speaker.htmhttp://electronics.howstuffworks.com/car-computer1.htmhttp://electronics.howstuffworks.com/microwave.htmhttp://electronics.howstuffworks.com/relay.htmhttp://electronics.howstuffworks.com/inside-cell-phone.htmhttp://www.geocities.com/SiliconValley/Peaks/3938/z80arki.htmhttp://www.geocities.com/SiliconValley/Peaks/3938/z80arki.htmhttp://electronics.howstuffworks.com/microprocessor.htmhttp://electronics.howstuffworks.com/gps.htmhttp://electronics.howstuffworks.com/gps.htmhttp://electronics.howstuffworks.com/inside-rc.htmhttp://electronics.howstuffworks.com/speaker.htmhttp://electronics.howstuffworks.com/car-computer1.htmhttp://electronics.howstuffworks.com/microwave.htmhttp://electronics.howstuffworks.com/relay.htmhttp://electronics.howstuffworks.com/inside-cell-phone.htmhttp://www.geocities.com/SiliconValley/Peaks/3938/z80arki.htmhttp://www.geocities.com/SiliconValley/Peaks/3938/z80arki.htmhttp://electronics.howstuffworks.com/microprocessor.htmhttp://electronics.howstuffworks.com/gps.htmhttp://electronics.howstuffworks.com/gps.htm


41/60

microcontroller chips -- chips that were originally designed to be low-cost, small, low-

power, embedded CPUs. The Motorola 6811 and Intel 8051 are both good examples of

such chips. There is also a line of popular controllers called "PIC microcontrollers"

created by a company called Microchip. By current standards, these CPUs are

incredibly minimalistic; but they are extremely inexpensive when purchased in large

quantities and can often meet the needs of a device's designer with just one chip.

A typical low-end microcontroller chip might have 1,000bytes of ROM and 20 bytes of

RAM on the chip, along with eight I/0 pins in large quantities, and are often very cheap.

Microsoft Word cannot be run on such a chip -- Microsoft Word requires perhaps 30

megabytes of RAM and a processor that can run millions of instructions per second. But

then, one does not need Microsoft Word to control a microwave oven, either. With a

microcontroller, one has one specific task on how to accomplish, and as such low-cost

and low-power performance is what is important.

4.3.3 Liquid Cristal Display

Figure 4.4 is a pictorial view of a liquid crystal display (LCD), it is a flat panel display,

electronic visual display, video display that uses the light modulating properties of

liquid crystals (LCs). LCs does not emit light directly.

They are used in a wide range of applications, including computer monitors, television,

instrument panels,aircraft cockpit displays, signage, etc. They are common in consumer

devices such as video players, gaming devices, clocks, watches, calculators, telephones

and flow metering display. LCDs have displaced cathode ray tube (CRT) displays in

most applications. They are usually more compact, lightweight, portable, less

expensive, more reliable, and easier on the eye. They are available in a wider range of

http://www.cs.ucr.edu/~dalton/i8051/http://www.microchip.com/http://www.microchip.com/http://electronics.howstuffworks.com/bytes.htmhttp://en.wikipedia.org/wiki/Flat_panel_displayhttp://en.wikipedia.org/wiki/Electronic_visual_displayhttp://en.wikipedia.org/wiki/Electronic_visual_displayhttp://en.wikipedia.org/wiki/Video_displayhttp://en.wikipedia.org/wiki/Liquid_Crystalshttp://en.wikipedia.org/wiki/Computer_monitorhttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Flight_instrumentshttp://en.wikipedia.org/wiki/Flight_instrumentshttp://en.wikipedia.org/wiki/Signagehttp://en.wikipedia.org/wiki/Clockhttp://en.wikipedia.org/wiki/Calculatorhttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Cathode_ray_tubehttp://www.cs.ucr.edu/~dalton/i8051/http://www.microchip.com/http://electronics.howstuffworks.com/bytes.htmhttp://en.wikipedia.org/wiki/Flat_panel_displayhttp://en.wikipedia.org/wiki/Electronic_visual_displayhttp://en.wikipedia.org/wiki/Video_displayhttp://en.wikipedia.org/wiki/Liquid_Crystalshttp://en.wikipedia.org/wiki/Computer_monitorhttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Flight_instrumentshttp://en.wikipedia.org/wiki/Signagehttp://en.wikipedia.org/wiki/Clockhttp://en.wikipedia.org/wiki/Calculatorhttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Cathode_ray_tube


42/60

screen sizes than CRT and plasma displays, and since they do not use phosphors, they

cannot suffer image burn-in.

LCDs are more energy efficient and offer safer disposal than CRTs. Its low electrical

power consumption enables it to be used in battery-powered electronic equipment. It is

an electronically modulated optical device made up of any number of segments filled

with liquid crystals and arrayed in front of a light source (backlight) or reflector to

produce images in color ormonochrome. The most flexible ones use an array of small

pixels.[17]

In spite of LCD's being a well proven and still viable technology, as display devices

LCDs are not perfect for all applications. The following are the advantages and

disadvantages of the component.

Very compact and light.

Low power consumption.

No geometric distortion.

Little or no flicker depending on backlight technology.

Not affected by screen burn-in.

No high voltage or other hazards present during repair/service.

Can be made in almost any size or shape.

No theoretical resolution limit

Limitedviewing angle, causing color, saturation, contrast and brightness to vary,

even within the intended viewing angle, by variations in posture.

Bleeding and uneven backlighting in some monitors, causing brightness

distortion, especially toward the edges.

http://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electro-optic_modulatorhttp://en.wikipedia.org/wiki/Liquid_crystalhttp://en.wikipedia.org/wiki/Light#Light_sourceshttp://en.wikipedia.org/wiki/Light#Light_sourceshttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Reflector_(photography)http://en.wikipedia.org/wiki/Monochromehttp://en.wikipedia.org/wiki/Pixelhttp://en.wikipedia.org/wiki/Liquid_crystal_display#cite_note-0http://en.wikipedia.org/wiki/Viewing_anglehttp://en.wikipedia.org/wiki/Viewing_anglehttp://en.wikipedia.org/wiki/Viewing_anglehttp://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electro-optic_modulatorhttp://en.wikipedia.org/wiki/Liquid_crystalhttp://en.wikipedia.org/wiki/Light#Light_sourceshttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Reflector_(photography)http://en.wikipedia.org/wiki/Monochromehttp://en.wikipedia.org/wiki/Pixelhttp://en.wikipedia.org/wiki/Liquid_crystal_display#cite_note-0http://en.wikipedia.org/wiki/Viewing_angle


43/60

Smearing and ghosting artifacts caused by slow response times (>8 ms) and

"sample and hold" operation.

Only one native resolution. Displaying resolutions either requires a video scaler,

lowering perceptual quality, or display at 1:1 pixel mapping, in which images will

be physically too large or won't fill the whole screen.

Fixedbit depth, many cheaper LCDs are only able to display 262,000 colors. 8-

bit S-IPS panels can display 16 million colors and have significantly better black

level, but are expensive and have slower response time.

Input lag

Dead or stuck pixels may occur either during manufacturing or through use.

In a constant on situation, thermalization may occur, which is when only part of

the screen has overheated and therefore looks discolored compared to the rest of the

screen.

Not all LCDs are designed to allow easy replacement of the backlight.

Cannot be used with light guns/pens.[18]

Figure 4.4a Typical picture of a liquid crystal display

http://en.wikipedia.org/wiki/Native_resolutionhttp://en.wikipedia.org/wiki/Video_scalerhttp://en.wikipedia.org/wiki/1:1_pixel_mappinghttp://en.wikipedia.org/wiki/1:1_pixel_mappinghttp://en.wikipedia.org/wiki/Color_depth#LCD_displayshttp://en.wikipedia.org/wiki/Input_laghttp://en.wikipedia.org/wiki/Defective_pixelhttp://en.wikipedia.org/wiki/Native_resolutionhttp://en.wikipedia.org/wiki/Video_scalerhttp://en.wikipedia.org/wiki/1:1_pixel_mappinghttp://en.wikipedia.org/wiki/Color_depth#LCD_displayshttp://en.wikipedia.org/wiki/Input_laghttp://en.wikipedia.org/wiki/Defective_pixel


44/60

Figure 4.4b Structure of a Liquid Crystal Display

A liquid crystal display consists of two substrates that form a "flat bottle" that contains

the liquid crystal mixture. The inside surfaces of the bottle or cell are coated with a

polymer that is buffed to align the molecules of liquid crystal. The liquid crystal



45/60

molecules align on the surfaces in the direction of the buffing. For twisted pneumatic

devices, the two surfaces are buffed orthogonal to one another, forming a 90 degree

twist of the liquid crystal from one surface to the other.

The helical structure has the ability to control light. A polarizer is applied to the front

and an analyzer/reflector is applied to the back of the cell. When randomly polarized

light passes through the front polarizer, it becomes linearly polarized. It then passes

through the front glass and is rotated by the liquid crystal molecules and passes through

the rear glass. If the analyzer is rotated 90 degree to the polarizer, the light passes

through the analyzer and be reflected back through the cell. The observer sees the

background of the display, which in this case, is the silver-gray of the reflector.

When an appropriate drive signal is applied to the cell electrodes, an electric field is set

up across the cell. The liquid crystal molecules re-align with the electric field

perpendicularly to the glass surface. The incoming linearly polarized light passes

through the cell unaffected and is absorbed by the rear analyzer. The observer sees a

black character on a sliver-gray background as indicated in figure 4.4b above. When the

electric field is turned off, the molecules relax back to their 90 twist structure. This is

referred to as a Positive Image, Reflective Viewing Mode.[19]

This display aids in the determination of actual product quantity emanating from the oil

field which is the main objective of the project for effective and efficient accountability.



46/60

Figure 4.5 shows a block diagram of microcontroller MSP430x412, MSP430x413

which forms the integral part of the circuit. This chip is the heart of the metering system

and the terminals are clearly labelled to indicate their functions.

Figure 4.5 Block diagram of microcontroller MSP430x412, MSP430x413



47/60

Table 4.4 Terminal functions

TERMINAL

NAME NO. I/O DESCRIPTION

AVCC 64Positive terminal that supplies SVS, brownout, oscillator, comparator A port, andLCD resistive divider circuitry, must not power up prior to DVcc.

AVSS 62

Negative terminal that supplies SVS, brownout, oscillator, comparator A. Needs to

be externally connected to DVss

DVCC 1Digital supply voltage, positive terminal. Supplies all parts, except those which aresupplied via Avcc.

DVSS 63Digital supply voltage, positive terminal. Supplies all parts, except those which aresupplied via Avcc/AVss.

NC

7, 10,

11 Not internally connected. Connection to vss recommended.

P1. 0/TAO 53 I/OGeneral purpose digital I/O timer _A, capture: CCIOA input, compare:Out0output/BSL transmit

P1. 1/TAO/MCLK 52 I/O General purpose digital I/O timer _A, capture: CCIOB input/MCLK output.

P1..2/TA1 51 I/O General-purpose digital I/O Timer_ O capture: CCI1A input, compare:Out1 output

P1.3/SVSOUT 50 I/O General-purpose digital I/O SVS comparator

P1.4 49 I/O General-purpose digital I/O

P1.5/TACLK/ACLK 48 I/O General-purpose digital I/O input of Timer_A clock/output of ACLK

P1.6/CAO 47 I/O General-purpose digital I/O Comparator_A input

P1.7/CA1 46 I/O General-purpose digital I/O Comparator_A input

P2.0/TA2 45 I/O General-purpose digital I/O Timer_A capture:CCI2A input, compare: Out2 output


P2.2/S23 35 I/O General-purpose digital I/O LCD segment output 23 (see Note 1)




P2.6/CAOUT/S19 31 I/OGeneral-purpose digital I/O /comparator_A output/LCD segment output 19 (seeNote 1)

















P4.7/S2 14 I/O General-purpose digital I/O LCD segment output 2(see Note 1)


P5.1/SO 12 I/O General-purpose digital I/O LCD segment output 0 (see Note 1)



48/60

COM 0 36 O Common output. COM0-3 are used for LCD backplanes

P5.2/COM1 37 I/O

General-purpose digital I/O Common output. COM0-3 are used for LCD

backplanes

P5.3/COM2 38 I/O


backplanes

P5.4/COM3 39 I/O


backplanes

R03 40 I Input port of positive forth positive (lowest) analogue LCD level (V5)

P5.5/R13 41 I/O

General-purpose digital I/O input port of third most positive analogue LCD level

(V4 or V3)

P5.6/R23 42 I/OGeneral-purpose digital I/O input port of second most positive analogue LCD level(V2)

P5.7/R33 43 I/O General-purpose digital I/O input port of most positive analogue LCD level (V1)






P6.5 4 I/O General-purpose digital I/OP6.6 5 I/O General-purpose digital I/O


RST/NMI 58 I Reset input/Nonmaskable interrupt input

TCK 57 I Test clock. TCK is the input port for device programming and test.

TDI/CLK 55 I Test data input/ Test clock input. The device protection fuse is connected to TDI.

TDO/TDI 54 I/O Test data output port TDO/TDI data output or programming data input terminal.

TMS 56 I Test mode select. TMS is used as an input port for device programming and test.

XIN 8 I Input port for crystal oscillator XT1. Standard or watch crystal can be connected.

XOUT 9 O Output terminal of crystal oscillator TX1.

QFN Pad NA NA QFN package pad connection to Vss

NOTE: LCD functions automatically when applicable LCD module control bit are

set.

4.3.4 Light Emitting Diode (LED)

Figure 4.6 shows a symbol of an LED which serve as indicator when the circuit in

functional state.

Figure 4.6 Symbol of an LED

http://upload.wikimedia.org/wikipedia/commons/e/e5/LED_symbol.svg


49/60

An LED is a specially fabricated semiconductor PN-junction diodes that emit

monochromatic (single colour) light when forward biased. When a PN-junction is

forward biased, free electrons cross the junction and fall into the holes. As these

electrons fall from a higher energy to a lower energy level, they radiate energy. In

ordinary diodes, this energy is radiated in a form of heat. But LEDs have the unique

ability of producing light while conducting current through them.[20]

LEDs are observed to be energy efficient, costly effective, small in size, light in weight

and then also they require no warm-up time and hence they have fast on-off switching.

This device was employed to serve as indicator when the metering system is switched to

on or off position.

4.4 Operation of the equipment

The designed volumetric metering system should be installed at the end of the fuel hose

adjacent to the nozzle or installed in line either horizontal or vertically. If installed and

used correctly, you can expect accuracy within 5%.

The meter is designed for use with gasoline, diesel fuel, kerosene, crude oil and any

other petroleum fluid. This volumetric metering system will turn on automatically upon

sensing fuel when activated or connected to power source. However, it can manually be

turned on by pressing the display bottom (display). It also turns off automatically if

not used for about one minute.

Furthermore, this volumetric metering system maintains two totals. The batch total

(TTL 1) may be set to zero and measures flow during a single use. The cumulative

total (TTL 2) provides continuous measurement and may not be manually reset.



50/60

When the cumulative total reaches a maximum reading of 9999, it automatically reset to

zero.

Press the DISPLAY button (DISPLAY) briefly to switch between TTL 1 and TTL 2.

With TTL 1 showing, hold the DISPLAY button down for three seconds to zero the

batch total.

Its flow rate capability is 10 to 100 LPM for pump or gravity flow systems with

pressure not exceeding 20.7 bar; operating temperature not below -10C and not

exceeding 54C and storage temperature not below -40C and not exceeding 70C.

4.5 Maintenance of the flow metering system

The volumetric metering system is virtually maintenance free if the meter is kept clean

and free of contaminants. It is extremely important that the rotor moves freely.

Periodically apply a penetrating lubricant on the rotor shaft and bearing if the rotor

sticks. Use a soft brush or small probe to remove debris deposits from the rotor.



51/60

CHAPTER FIVE

5.0 RESULT AND DISCUSSION

5.1 Results

The objective for the design of the oil volume metering system is to ensure proper

petroleum product accountability in the oil industry/fields to enhance revenue

generation. There have been instances where product spillage has occurred due to the

inaccurate modes of measurement. Any time there was petroleum under delivery or over

delivery it posed lot of challenges in the operation of that establishment.

The Consequences of crude oil spillage cannot be over-emphasised with regards to its

volatility. It could trigger fire when a little spark or heat is introduced and this could

cause serious destruction to properties and loss of lives.

The demonstration of the prototype exhibited that the aim of the accomplished its

desired results.

When the system was put to test the following result was obtained:

The meter was connected to a tap and was able to dispense water into a 1.5 litre

container which registered the exact quantity.

The meter was able to reset to zero to ensure it readiness to execute another

operation in respect of tank loading/discharging.

This could be interpreted that the system is functional and would serve the required

purpose which was intended for.

Consequently when it is employ in FPSO, it would assist in the determination of

product quantity released from their oil field effectively and efficiently.



52/60

5.2 Cost Analysis

The major hardware employed in the project was Microcontroller chip, sensor, liquid

crystal display, step-down transformer, volume meter housing, rectifier and printed

circuit board.

5.1 Table of material cost

Item No. Name of the item Cost in Gh

1 Microcontroller chip 450

2 Liquid crystal display 55

3 Meter housing 85

4 Rectifier 25

5 Transformer 5

6 Packaging 50

7 Fittings 25

8 Printed circuit board 30

9 Power cord 5

10 Sensor 85

Total 815

1. Cost of the design of the metering system (labour cost) = GH300

2. Overhead cost (10%) = GH55.75

Total Cost = GH1170.75

Volumetric metering system is capital intensive in respect of acquisition of essential

materials such as microcontroller, sensor, meter housing, LCD and printed circuit

board; conversely it is cost effective for short and long term project.

Close to 60% of the materials could be obtained locally, for instance step down

transformer, rectifiers, resisters, voltage regulators power cord etc.



53/60

5.3 Discussions

Comparing the digital Volumetric metering system to the existing ancient mode of

measurement in FPSO oil field, thus the use of measuring bar and level gauges whi

project abolo

Documents