SUBMITTED BY:

ANKUR NAHAR

MECHANICAL ENGG.

IIT MANDI

JUNE - JULY

2011

SUBMITTED BY:

VINAY GUPTA

MECHANICAL ENGG.

NIT HAMIRPUR

Summer Training Report

INDEX

1. Acknowledgements

2. About the company

a. Evolution of NTPC

b. NTPC group

c. Installed Capacity

d. NTPC Strategies

e. NTPC Faridabad

f. International Cell

g. NTPC Operations

3. Gas to Electricity Conversion

a. Introduction

b. Gas turbine

c. Steam turbine

d. Heat Recovery Steam Generator

e. Deaerator

f. Cooling towers

g. Condensor

4. Automation and Control

a. Control and Monitoring Mechanisms

b. Pressure Control

c. Temperature Control

d. Flow Control

e. Control Valves

ACKNOWLEDGEMENTS

I would firstly wish to thank Mrs. ……………………………. for allowing me to

undergo summer training at NTPC Faridabad , all of the HR team of the Institute

for their continued guidance. I would also wish to convey my warm regards to Mr.

……….. and Mr. …………….. for providing me with all the knowledge database

that I needed for this report.

I would also like to thank Mr. ……………… , TPO – …………………….

…………, for providing me this wonderful opportunity to work with the NTPC

family

ABOUT THE COMPANY

Corporate Vision:“A world class integrated power major, powering India’s growth, with increasing global presence”

Core Values:B-Business EthicsC-Customer FocusO-Organizational & Professional prideM-Mutual Respect and TrustI- Innovation & SpeedT-Total quality for Excellence

NTPC Limited is the largest thermal power generating company of India. A public sector company, it was incorporated in the year 1975 to accelerate power development in the country as a wholly owned company of the Government of India. At present, Government of India holds 89.5% of the total equity shares of the company and the balance 10.5% is held by FIIs, Domestic Banks, Public and others. Within a span of 31 years, NTPC has emerged as a truly national power company, with power generating facilities in all the major regions of the country.

NTPC’s core business is engineering, construction and operation of power generating plants. It also provides consultancy in the area of power plant constructions and power generation to companies in India and abroad. As on date the installed capacity of NTPC is 27,904 MW through its 15 coal based (22,895 MW), 7 gas based (3,955 MW) and 4 Joint Venture Projects (1,054 MW). NTPC acquired 50% equity of the SAIL Power Supply Corporation Ltd. (SPSCL). This JV company operates the captive power plants of Durgapur (120 MW), Rourkela (120 MW) and Bhilai (74 MW). NTPC also has 28.33% stake in Ratnagiri Gas & Power Private Limited (RGPPL) a joint venture company between NTPC, GAIL, Indian Financial Institutions and Maharashtra SEB Holding Co. Ltd.

NTPC’s share on 31 Mar 2007 in the total installed capacity of the country was 20.18% and it contributed 28.50% of the total power generation of the country during 2006-07.

EVOLUTION OF NTPC

NTPC was set up in 1975 with 100% ownership by the Government of India. In the last 30 years, NTPC has grown into the largest power utility in India.

In 1997, Government of India granted NTPC status of “Navratna’ being one of the nine jewels of India, enhancing the powers to the Board of Directors.

NTPC became a listed company with majority Government ownership of 89.5%.

NTPC becomes third largest by Market Capitalisation of listed companies

The company rechristened as NTPC Limited in line with its changing business portfolio and transform itself from a thermal power utility to an integrated power utility.

NTPC is the largest power utility in India, accounting for about 20% of India’s installed capacity.

1975 1975

1997 1997

2005 2005

20042004

NTPC GROUP

NTPC Limited

Subsidiaries

Joint Ventures

NTPC Vidyut VyaparNigam Limited 100%

NTPC Electric SupplyCo. Limited

100%

Pipavav PowerDevelopment Co. Ltd

100%

NTPC Hydro Limited100%

Utility PowertechLimited

50%

NTPC Alstom PowerServices Pvt. Limited

50%

Bhilai Electric Supply Co. Pvt. Limited

50%

NTPC-SAIL PowerCompany Pvt. Limited

50%NTPC-SAIL Power

Company Pvt. Limited50

Ratnagiri Gas & Power Private Ltd

28.33%

PTC India Limited8%

NTPC TamilnaduEnergy Co. Limited

50%

INSTALLED CAPACITY

AN OVERVIEW

Projects No. of Projects Commissioned

Capacity(MW)

NTPC OWNED

COAL 15 22,895

GAS/LIQ. FUEL 07 3,955

TOTAL 22 26,850

OWNED BY JVCs

Coal 3 314*

Gas/LIQ. FUEL 1 740**

GRAND TOTAL 26 27,904

* Captive Power Plant under JVs with SAIL** Power Plant under JV with GAIL, FIs & MSEB

PROJECT PROFILE

Coal Based Power Stations

Coal based State Commissioned

Capacity(MW)

1. Singrauli Uttar Pradesh 2,000

2. Korba Chattisgarh 2,100

3. Ramagundam Andhra Pradesh 2,600

4. Farakka West Bengal 1,600

5. Vindhyachal Madhya Pradesh 3,260

6. Rihand Uttar Pradesh 2,000

7. Kahalgaon Bihar 1,340

8. NTCPP Uttar Pradesh 840

9. Talcher Kaniha Orissa 3,000

10. Unchahar Uttar Pradesh 1,050

11. Talcher Thermal Orissa 460

12. Simhadri Andhra Pradesh 1,000

13. Tanda Uttar Pradesh 440

14. Badarpur Delhi 705

15. Sipat Chattisgarh 500

Total (Coal) 22,895

Gas/Liq. Fuel Based Power Stations

Gas based State Commissioned

Capacity(MW)

16. Anta Rajasthan 413

17. Auraiya Uttar Pradesh 652

18. Kawas Gujarat 645

19. Dadri Uttar Pradesh 817

20. Jhanor-Gandhar Gujarat 648

21. Rajiv Gandhi CCPP

Kayamkulam Kerala 350

22. Faridabad Haryana 430

Total (Gas) 3,955

Power Plants with Joint Ventures

Coal Based State Fuel Commissioned

Capacity(MW)

23. Durgapur West Bengal Coal 120

24. Rourkela Orissa Coal 120

25. Bhilai Chhattisgarh Coal 74

26. RGPPL Maharastra Naptha/LNG 740

Total(JV) 1054

Grand Total (Coal + Gas + JV) 27,904

Projects Under Implementation

Coal / Hydro State Fuel

Additional Capacity Under Implementation (MW)

1. KahalgaonStage II (Phase I) (Phase II)

Bihar Coal500500

2. Sipat (Stage I) (Stage II) Chhattisgarh Coal1980500

3. Barh Bihar Coal 1980

4. Bhilai (Exp. Power Project-JV with SAIL)

Chhattisgarh Coal 500

5. Korba (Stage III) Chhattisgarh Coal 500

6. Farakka (Stage III) West Bengal Coal 500

7. NCTPP (Stage II) Uttar Pradesh Coal 980

8. Simhadri (Stage II)Andhra Pradesh

Coal 1000

9. Koldam (HEPP)Himachal Pradesh

Hydro 800

10. Loharinag Pala (HEPP) Uttarakhand Hydro 600

11. Tapovan Vishnugad (HEPP)

Uttarakhand Hydro 520

Total (Coal + Hydro) 10,860

NTPC STRATEGIES

Technological Initiatives

Introduction of steam generators (boilers) of the size of 800 MW

Nurturing Human

Resource

Technologyinitiatives

Exploit newbusiness

opportunities

Further enhance

fuel security

Maintain sectorLeadership

position through

expansion

SustainableDevelopment

STRATEGIES - NTPC

Integrated Gasification Combined Cycle (IGCC) Technology Launch of Energy Technology Center -A new initiative for

development of technologies with focus on fundamental R&D The company sets aside upto 0.5% of the profits for R&D Roadmap developed for adopting ‘Clean Development Mechanism’ to help get / earn ‘Certified Emission Reduction

Corporate Social Responsibility

As a responsible corporate citizen NTPC has taken up number of CSR initiatives

NTPC Foundation formed to address Social issues at national level NTPC has framed Corporate Social Responsibility Guidelines

committing up to 0.5% of net profit annually for Community Welfare Measures on perennial basis

The welfare of project affected persons and the local population around NTPC projects are taken care of through well drawn Rehabilitation and Resettlement policies

The company has also taken up distributed generation for remote rural areas

NTPC Faridabad has been doing development work in the nearby villages of Mujedi under the guidance of Mrs. Manjula Sengupta with an annual budget of Rs Ten lacs.

Environment Management

All stations of NTPC are ISO 14001 certified Various groups to care of environmental issues The Environment Management Group Ash Utilisation Division Afforestation Group Centre for Power Efficiency & Environment Protection Group on Clean Development Mechanism

NTPC is the second largest owner of trees in the country after the Forest department

Partnering government in various initiatives

Consultant role to modernize and improvise several plants across the country

Disseminate technologies to other players in the sector Consultant role “Partnership in Excellence” Programme for

improvement of PLF of 15 Power Stations of SEBs. Rural Electrification work under Rajiv Gandhi Grameen Vidyutikaran

Yojana

NTPC FARIDABAD PLANT

Location Village – Mujedi,P.O. Neemka,Dist. Faridabad,Haryana

Govt. approved date 25.07.1997

Plant Capacity 430MW (Nominal)

Plant Configuration 2(GT)+1STGT-143 MW, ST-144MW

Land Availability

Fuel Used

Available

Gas and Naptha

Gas Source HBJ Pipeline

Water Source Rampur distributories of Gurgaon canal

Financing OECF, Japan

Project Cost Rs.1163.60 Cr. (IV Qtr.96)

Beneficiary States Haryana (100%)

Commissioning Date GT-I : June 1999GT-II : October 1999ST : July 2000

International Assistance OECF

NTPC INTERNATIONAL CELLKeeping its proactive tradition, NTPC launched a separate International Cell to meet the varied needs of IPPs ( Independent Power Producers) and other International clients who are looking for a world class service in power sector. The Cell is especially tuned to meet the requirements of International clients in terms of quick response, flexible service options and to deliver value for money.

Pursuing Business Opportunities in:• Sri Lanka

• Saudi Arabia• UAE• Iran• Jordan• Bahrain• Egypt•

Malaysia•

Indonesia•

Vietnam• Thailand• Sudan• Niger• Yemen

NTPC OPERATIONSThe operating performance of NTPC has been considerably above the national average. The availability factor for coal stations has increased from 85.03 % in 1997-98 to 90.09 % in 2006-07, which compares favourably with international standards. The PLF has increased from 75.2% in 1997-98 to 89.4% during the year 2006-07 which is the highest since the inception of NTPC.

It may be seen from the table below that while the installed capacity has increased by 56.40% in the last nine years, the employee strength went up by only 3.34%

Description Unit1997-98

2006-07% of increase

Installed Capacity MW16,847

26,350 56.40

Generation MUs

97,609

1,88,674

93.29

No. of employees No.23,585

24,375 3.34

Generation/employee

MUs

4.14 7.74 86.95

ECOLOGICAL MONITORING PROGRAMME

NTPC has undertaken a comprehensive Ecological Monitoring Programme

through Satellite Imagery Studies covering an area of about 25 Kms radius around

some of its major plants. The studies have been conducted through National

Remote Sensing Agency (NRSA), Hyderabad at its power stations at

Ramagundam, Farakka, Korba, Vindhyachal, Rihand and Singrauli. These studies

have revealed significant environmental gains in the vicinity areas of the project as

a result of pursuing sound environment management practices. Some of these

important gains which have been noticed are increase in dense forest area, increase

in agriculture area, increase in average rainfall, decrease in waste land etc. In

general, the studies, as such, have revealed that there is no significant adverse

impact on the ecology due to the project activities in any of these stations. Such

studies conducted from time to time around a power project have established

comprehensive environment status at various post operational stages of the project.

USE OF WASTE PRODUCTS & SERVICES -ASH UTILIZATION

Ash is the main solid waste which is put into use for various products and services.

NTPC has adopted user friendly policy guidelines on ash utilisation.

In order to motivate entrepreneurs to come forward with ash utilisation schemes,

NTPC offers several facilities and incentives. These include free issue of all types

of ash viz. Dry Fly Ash / Pond Ash / Bottom Ash and infrastructure facilities,

wherever feasible. Necessary help and assistance is also offered to facilitate

procurement of land, supply of electricity etc from Government Authorities.

Necessary techno-managerial assistance is given wherever considered necessary.

Besides, NTPC uses only ash based bricks and Fly Ash portland pozzolana cement

(FAPPC) in most of its construction activities. Demonstration projects are taken up

in areas of Agriculture, Building materials, Mine filling etc. The utilisation of ash

and ash based products is progressively increasing as a result of the concrete

efforts of these groups.

LINE DIAGRAM SHOWING GAS TO ELECTRICITY CONVERSION AT FARIDABAD GAS POWER PLANT

NTPC Faridabad has Two Gas Turbines manufactured by Seimens and One Steam Turbine from BHEL

Introduction

The basic principle of the Combined Cycle is simple: burning gas in a gas turbine (GT)produces not only power - which can be converted to electric power by a coupled generator but also fairly hot exhaust gases. Routing these gases through a water-cooled heat exchanger produces steam, which can be turned into electric power with a coupled steam turbine and generator.

This set-up of Gas Turbine, waste-heat boiler, steam turbine and generators is called a combined cycle. This type of power plant is being installed in increasing numbers round the world where there is access to substantial quantities of natural gas. This type of power plant produces high power outputs at high efficiencies and with low emissions. It is also possible to use the steam from the boiler for heating purposes so such power plants can operate to deliver electricity alone

Efficiencies are very wide ranging depending on the lay-out and size of the installation. Developments needed for this type of energy conversion is only for the gas turbine. Both waste heat boilers and steam turbines are in common use and well-developed, without specific needs for further improvement.

Gas turbine

The gas turbine (Brayton) cycle is one of the most efficient cycles for the conversion of gas fuels to mechanical power or electricity. The use of distillate liquid fuels, usually diesel, is also common where the cost of a gas pipeline cannot be justified. Gas turbines have long been used in simple cycle mode for peak lopping in the power generation industry, where natural gas or distillate liquid fuels have been used, and where their ability to start and shut down on demand is essential.

Gas turbines have also been used in simple cycle mode for base load mechanical power and electricity generation in the oil and gas industries, where natural gas and process gases have been used as fuel. Gas fuels give reduced maintenance costs compared with liquid fuels, but the cost of natural gas supply pipelines is generally only justified for base load operation.

More recently, as simple cycle efficiencies have improved and as natural gas prices have fallen, gas turbines have been more widely adopted for base load power generation, especially in combined cycle mode, where waste heat is recovered in waste heat boilers, and the steam used to produce additional electricity. The efficiency of operation of a gas turbine depends on the operating mode, with full load operation giving the highest efficiency, with efficiency deteriorating rapidly with declining power output.

Steam turbine

The operation of the turbine of steam is based on the thermodynamic principle thatexpresses that when the steam expands it diminishes its temperature and it decreases its internal energy

This situation reduction of the energy becomes mechanical energy for the acceleration of the particles of steam, what allows have a great quantity of energy directly. When the steam expands, the reduction of its internal energy can produce an increase of the speed from the particles. To these speeds the available energy is very high, although the particles are very slight.

The action turbine, it is the one that the jets of the turbine are subject of the shell of the turbine and the poles are prepared in the borders of wheels that rotate around a central axis.The steam passes through the mouthpieces and it reaches the shovels. These absorb a part of the kinetic energy of the steam in expansion that it makes rotate the wheel that with her the axis to the one that this united one. The steam enters in an end it expands through a series of mouthpieces until it has lost most of its internal energy. So that the energy of the steam is used efficiently in turbines it is necessary to use several steps in each one of which it becomes kinetic energy a part of the thermal energy of the steam. If the energy conversion was made in a single step the rotational speed of the wheel was very excessive.

Heat Recovery Steam Generator

In the design of an HRSG, the first step normally is to perform a theoretical heat balance which will give us the relationship between the tube side and shell side process. We must decide the tube side components which will make up our HRSG unit, but only it considers the three primary coil types that may be present, Evaporator, Superheater and Economizer.

Evaporator Section: The most important component would, of course, be the Evaporator Section. So an evaporator section may consist of one or more coils. In these coils, the effluent (water), passing through the tubes is heated to the saturation point for the pressure it is flowing.

Superheater Section: The Superheater Section of the HRSG is used to dry the saturated vapour being separated in the steam drum. In some units it may only be heated to little above the saturation point where in other units it may be superheated to a significant temperature for additional energy storage. The Superheater Section is normally located in the hotter gas stream, in front of the evaporator.

Economizer Section: The Economizer Section, sometimes called a preheater or preheat coil, is used to preheat the feedwater being introduced to the system to replace the steam (vapour) being removed from the system via the superheater or steam outlet and the water loss through blowdown. It is normally located in the colder gas downstream of the evaporator. Since the evaporator inlet and outlet temperatures are both close to the saturation temperature for the system pressure, the amount of heat that may be removed from the flue gas is limited due to the approach to the evaporator, whereas the economizer inlet temperature is low,allowing the flue gas temperature to be taken lower.

Deaerator

The deaerating boiler feedwater system eliminates the need of expensive oxygen scavenger chemicals and also offers the following advantages:

Removes carbon dioxide as well as oxygen. Raises the boiler feedwater temperature, eliminating thermal shock in

boilers. Improves overall boiler room efficiency. Feedwater pumps are sized for each individual application - assuring total

compatibility and optimum operation.

HOW DOES IT WORK?

Undeaerated fresh water is fed into the deaerator through the inlet water connection. This water passes through the steam-filled heating and venting section. The water temperature is raised and many of the undissolved gases are released. As the water passes through the assembly, it flows to a scrubber section where final deaeration is accomplished by scrubbing the water with oxygen free steam. Thissteam is induced through a stainless steel spray valve assembly which causes the high velocity steam to break the water down to a fine mist through a violent scrubbing action. The deaerated water spills over to the tanks storage compartment for use by the boiler, and the gases are vented to the atmosphere.

Cooling towers

A cooling tower is an equipment used to reduce the temperature of a water streamby extracting heat from water and emitting it to the atmosphere. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere

The tower vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 meters tall and 100 meters in diameter, or rectangular structure that can be over 40 meters tall and 80 meters long

Cooling towers were constructed primarily with wood, including the frame,casing, louvers, fill and cold-water basin. Sometimes the cold-water basin was made of concrete. Today, manufacturers use a variety of materials to construct cooling towers. Materials are chosen to enhance corrosion resistance, reduce maintenance, and promote reliability and long service life. Galvanized steel, various grades of stainless steel, glass fiber, and concrete are widely used in tower construction, as well as aluminum and plastics for some components

Condensor

The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases.

The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes.

For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 °C where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented.

Water Treatment Plant

AUTOMATION AND CONTROL SYSTEM

AUTOMATION: THE DEFINITION

The word automation is widely used today in relation to various types of

applications, such as office automation, plant or process automation.

This subsection presents the application of a control system for the automation of a

process / plant, such as a power station. In this last application, the automation

actively controls the plant during the three main phases of operation: plant start-up,

power generation in stable or put During plant start-up and shut-down, sequence

controllers as well as long range modulating controllers in or out of operation

every piece of the plant, at the correct time and in coordinated modes, taking into

account safety as well as overstressing limits.

During stable generation of power, the modulating portion of the automation

system keeps the actual generated power value within the limits of the desired load

demand.

During major load changes, the automation system automatically redefines new

set points and switches ON or OFF process pieces, to automatically bring the

individual processes in an optimally coordinated way to the new desired load

demand. This load transfer is executed according to pre- programmed adaptively

controlled load gradients and in a safe way.

AUTOMATION: THE BENEFITS

The main benefits of plant automation are to increase overall plant availability and efficiency. The increase of these two factors is achieved through a series of features summarized as follows:

Optimisation of house load consumption during plant start- up, shut-down and operation, via:

Faster plant start-up through elimination of control errors creating delays. Faster sequence of control actions compared to manual ones. Figures 1

shows the sequence of a rapid restart using automation for a typical coal-fired station. Even a well- trained operator crew would probably not be able to bring the plant to full load in the same time without considerable risks.

Co-ordination of house load to the generated power output.

Ensure and maintain plant operation, even in case of disturbances in the control system, via:

Coordinated ON / OFF and modulating control switchover capability from a sub process to a redundant one.

Prevent sub-process and process tripping chain reaction following a process component trip.

Reduce plant / process shutdown time for repair and maintenance as well as repair costs, via:

Protection of individual process components against overstress (in a stable or unstable plant operation).

Bringing processes in a safe stage of operation, where process components are protected against overstress

PROCESS STRUCTURE

Analysis of processes in Power Stations and Industry advocates the advisability of dividing the complex overall process into individual sub-processes having distinctly defined functions. This division of the process in clearly defined groups, termed as FUNCTIONAL GROUPS, results in a hierarchical process structure. While the hierarchical structure is governed in the horizontal direction by the number of drives (motorised valves, fans, dampers, pumps, etc.) in other words the size of the process; in the vertical direction, there is a distinction made between three fundamental levels, these being the: -

Drive Level

Function Group Level

Unit Level.

To the Drive Level, the lowest level, belong the individual process equipment and

associated electrical drives.

The Function Group is that part of the process that fulfils a particular defined task

e.g., Induced Draft Control, Feed Water Control, Blooming Mill Control, etc. Thus

at the time of planning it is necessary to identify each function group in a clear

manner by assigning it to a particular process activity. Each function group

contains a combination of its associated individual equipment drives. The drive

levels are subordinate to this level. The function groups are combined to obtain the

overall process control function at the Unit Level.

The above three levels are defined with regard to the process and not from the

control point of view.

CONTROL SYSTEM STRUCTURE

The primary requirement to be fulfilled by any control system architecture is that it

be capable of being organized and implemented on true process-oriented lines. In

other words, the control system structure should map on to the hierarchy process

structure.

BHEL’s PROCONTROL P®, a microprocessor based intelligent remote

multiplexing system, meets this requirement completely.

SYSTEM OVERVIEW

The control and automation system used here is a micro based intelligent

multiplexing system This system, designed on a modular basis, allows to tighten

the scope of control hardware to the particular control strategy and operating

requirements of the process

Regardless of the type and extent of process to control provides system uniformity

and integrity for:

Signal conditioning and transmission

Modulating controls

CONTROL AND MONITORING MECHANISMS

There are basically two types of Problems faced in a Power Plant

Metallurgical

Mechanical

Mechanical Problemcan be related to Turbines that is the max speed permissible

for a turbine is 3000 rpm , so speed should be monitored and maintained at that

level

Metallurgical Problem can be view as the max Inlet Temperature for Turbile is

1060 oC so temperature should be below the limit.

Monitoring of all the parameters is necessary for the safety of both:

Employees

Machines

So the Parameters to be monitored are :

Speed

Temperature

Current

Voltage

Pressure

Eccentricity

Flow of Gases

Vaccum Pressure

Valves

Level

PRESSURE MONITORING

Pressure can be monitored by three types of basic mechanisms

Switches

Gauges

Transmitter type

For gauges we use Bourden tubes : The Bourdon Tube is a non liquid pressure

measurement device. It is widely used in applications where inexpensive static

pressure measurements are needed.

A typical Bourdon tube contains a curved tube that is open to external pressure

input on one end and is coupled mechanically to an indicating needle on the other

end, as shown schematically below.

Typical Bourdon Tube Pressure Gages

Transmitter types use transducers (electrical to electrical normally) they are used

where continuous monitoring is required

Normally capacitive transducers are used

For Switches pressure swithes are used and they can be used for digital means of

monitoring as swith being ON is referred as high and being OFF is as low.

All the monitored data is converted to either Current or Voltage parameter.

The Plant standard for current and voltage are as under

Voltage : 0 – 10 Volts range

Current : 4 – 20 milliAmperes

We use 4mA as the lower value so as to check for disturbances and wire breaks.

Accuracy of such systems is very high .

ACCURACY : + - 0.1 %

The whole system used is SCADA based

INPUT 4-20 mA

ALARM

We use DDCMIC control for this process.Programmable Logic Circuits ( PLCs) are used in the process as they are the heardt of Instrumentation .

PressureElectricity

Start Level low Pressure in line Level High

High level pump Electricity

Stop Pressure

Electricity

BASIC PRESSURE CONTROL MECHANISM

Hence PLC selection depends upon the Criticality of the Process

ANALOG INPUT MODULE

MICRO PROCESSOR

HL switch

LL switch

AND

OR

TEMPERATURE MONITORING

We can use Thernocouples or RTDs for temperature monitoring

Normally RTDs are used for low temperatures.

Thermocoupkle selection depends upon two factors:

Temperature Range

Accuracy Required

Normally used Thermocouple is K Type Thermocouple:

Chromel (Nickel-Chromium Alloy) / Alumel (Nickel-Aluminium Alloy)

This is the most commonly used general purpose thermocouple. It is inexpensive

and, owing to its popularity, available in a wide variety of probes. They are

available in the −200 °C to +1200 °C range. Sensitivity is approximately 41

µV/°C.

We pass a constant curre t through the RTD. So that if R changes then the Voltage

also changes

RTDs used in Industries are Pt100 and Pt1000

Pt100 : 0 0C – 100 Ω ( 1 Ω = 2.5 0C )

Pt1000 : 0 0C - 1000Ω

Pt1000 is used for higher accuracy

The gauges used for Temperature measurements are mercury filled Temperature

gauges.

FLOW MEASUREMENT

Flow measurement does not signify much and is measured just for metering

purposes and for monitoring the processes

ROTAMETERS:

A Rotameter is a device that measures the flow rate of liquid or gas in a closed

tube. It is occasionally misspelled as 'rotometer'.

It belongs to a class of meters called variable area meters, which measure flow rate

by allowing the cross sectional area the fluid travels through to vary, causing some

measurable effect.

A rotameter consists of a tapered tube, typically made of glass, with a float inside

that is pushed up by flow and pulled down by gravity. At a higher flow rate more

area (between the float and the tube) is needed to accommodate the flow, so the

float rises. Floats are made in many different shapes, with spheres and spherical

ellipses being the most common. The float is shaped so that it rotates axially as the

fluid passes. This allows you to tell if the float is stuck since it will only rotate if it

is not.

For Digital measurements Flap system is used.

For Analog measurements we can use the following methods :

Flowmeters

Venurimeters / Orifice meters

Turbines

Massflow meters ( oil level )

Ultrasonic Flow meters

Magnetic Flowmeter ( water level )

Selection of flow meter depends upon the purpose , accuracy and liquid to be

measured so different types of meters used.

Turbine type are the simplest of all.

They work on the principle that on each rotation of the turbine a pulse is generated

and that pulse is counted to get the flow rate.

VENTURIMETERS :

Referring to the diagram, using Bernoulli's equation in the special case of

incompressible fluids (such as the approximation of a water jet), the theoretical

pressure drop at the constriction would be given by (ρ/2)(v22 - v1

2).

And we know that rate of flow is given by:

Flow = k √ (D.P)

Where DP is Differential Presure or the Pressure Drop.

CONTROL VALVES

A valve is a device that regulates the flow of substances (either gases, fluidized

solids, slurries, or liquids) by opening, closing, or partially obstructing various

passageways. Valves are technically pipe fittings, but usually are discussed

separately.

Valves are used in a variety of applications including industrial, military,

commercial, residential, transportation. Plumbing valves are the most obvious in

everyday life, but many more are used.

Some valves are driven by pressure only, they are mainly used for safety purposes

in steam engines and domestic heating or cooking appliances. Others are used in a

controlled way, like in Otto cycle engines driven by a camshaft, where they play a

major role in engine cycle control.

Many valves are controlled manually with a handle attached to the valve stem. If

the handle is turned a quarter of a full turn (90°) between operating positions, the

valve is called a quarter-turn valve. Butterfly valves, ball valves, and plug valves

are often quarter-turn valves. Valves can also be controlled by devices called

actuators attached to the stem. They can be electromechanical actuators such as an

electric motor or solenoid, pneumatic actuators which are controlled by air

pressure, or hydraulic actuators which are controlled by the pressure of a liquid

such as oil or water.

So there are basically three types of valves that are used in power industries

besides the handle valves. They are :

Pneumatic Valves – they are air or gas controlled which is compressed to

turn or move them

Hydraulic valves – they utilize oil in place of Air as oil has better

compression

Motorised valves – these valves are controlled by electric motors