plant utility and maintanance assisgnment

8/3/2019 Plant Utility and Maintanance Assisgnment

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PLANT UTILITY AND MAINTANANCE

Plant utility is the main utility in all industry to design a project or run a industry work. It is

heart of the plant serving all kinds of life blood to the complex system. Therefore, without

any of this equipment the industry could not perform in the global level. So without utilities,the equipment inside the plant cannot operate. In a plant, the utilities are dividing into a few

scopes which are:

I. Water system

II. Steam system

III. Fuel gas system

IV. Plant and instrument air

V. Nitrogen

VI. Product storage or transfer

VII. Electrical supply and distribution system

VIII. Feed stock storage

All the scopes have their own function. All this commodities are very important to run a

plant. In different industries, the function might be quite different.

1. Water system

Water system is an important industry requirement .Water system consist of mainly of

Water tower

Pump

tank

A water tower is an incredibly simple device. It is also called elevated water tank. Although

water towers come in all shapes and sizes, they all do the same thing. A water tower is simply

a large, elevated tank of water. Water towers are tall to provide pressure. Each foot of height

provides 0.43 PSI (pounds per square Inch) of pressure.

A typical municipal water supply runs at between 50 and 100 PSI because major appliances

require at least 20 to 30 PSI. The water tower must be tall enough to supply that level of

pressure to all of the appliances in the area of the tower. So water towers are typically located

on high ground, and they are tall enough to provide the necessary pressure. In hilly regions, a

tower can sometimes be replaced by a simple tank located on the highest hill in the area. A

water tower's tank is normally quite large. A typical water tower might hold 50 times the

water in a normal swimming pool. Typically, a water tower's tank is sized to hold about a

day's worth of water for the community served by the tower. If the pumps fail, for example,



during a power failure, the water tower holds enough water to keep things flowing for about a

day.

One of the big advantages of a water tower is that it lets a municipality size its pumps for

average rather than peak demand. Say that the water consumption for a pumping station

averages 500 gallons of water per minute or 720,000 gallons over the course of a day, there

will be times during the day when water consumption in the industry is much greater than

500 gallons per minute. Because of the water tower, the municipality can purchase a 500-

gallon-per-minute pump and let the water tower handle the peak demand. At night, when

demand normally falls to practically zero, the pump can make up the difference and refill the

water tower. The water is treated in a water treatment plant to remove sediment (by filtration

and settling) and bacteria (with ozone, ultraviolet light and chlorine). The output from the

water treatment plant is clear, germ-free water. A high-lift pump pressurizes the water and

sends it to the water system's primary feeder pipes. If the pump is producing more water than

the water system needs, the excess flows automatically into the tank. If the factory is

demanding more water than the pump can supply, then water flows out of the tank to meet

the need.



Ground water tank is made of lined carbon steel, it may receive water from water well or

from surface water allowing a large volume of water to be placed in inventory and used

during peak demand cycles.

2. Steam system

A steam system is a complex arrangement of equipment and piping that works

together to produce and circulate steam at a variety of pressures and temperatures.

Since steam is used in so many industrial applications most chemical plants and

refineries have their own steam generation facilities. In a closed steam system, a

condensate return header is used to remove slugs of water or condensate from the live

steam line. This treated water collects in low points in the system where devices

called steam traps direct flow back toward the boiler. A vessel called a deaerator is

used to collect fluid from the condensate return header. The deaerator is designed to



remove excess air from the system. Demineralized makeup water is often added to the

deaerator. The cooled condensate is fed back into the boiler where it is changed into

steam.

A typical steam system will include the following equipment:

• Boiler (fire tube or water tube)

• Steam header system (low, medium and high pressure)

• Condensate return system (steam traps, valves, piping, pumps)

• Deaerator system

3. Condensate Recovery System

The condensate recovery system is separated into clean and suspect (dirty) condensate

sections. Clean condensate is routed to the deaerator. Suspect condensate is collected from

steam users where the process side pressure is higher than the steam pressure. This

condensate is considered to be suspect because a mechanical failure, such as tube leakage or

failure could cause contamination, and reuse of contaminated condensate could seriously

damage the steam generators and turbines. Suspect condensate collected in a drum is closely

monitored for hydrocarbon contaminations. Depending upon the results of analysis, the

condensate is pumped either through a carbon filter and then routed to the deaerator.

4. Fuel Gas System

Most industrial manufacturers purchase natural gas (NG) from suppliers. A high-

pressure pipeline generally delivers gas to the plant (Figure 13.7-1). A pressure letdown

station located near one of the plant entrances meters flow to the plant. The letdown station

consists of multiple control valves, two of which are normally in service for backup.

Additional valves are provided for peak loads such as unit startups. The letdown/meter

control valve is in operation at all times. A second valve opens when the flow rate is high and

closes at low flow rates, thereby making possible more accurate metering of the gas flow.

The plant natural gas distribution header normally runs around 200 to 250 psig. Each process

unit has its own pressure-control station that usually maintains the unit pressure between 60

and 100 psig.

Natural gas is used to supplement the fuel gas produced at a unit in order to meet furnace and

boiler demands. Natural gas is also used as a purge medium in unit startup and shutdown.

Fuel gas generally consists of plant-produced process gas that is augmented with purchased

natural gas to satisfy the units energy demand. Fuel gas required is typically produced

internally during normal unit operations. During a startup mode or emergency mode, where

no internal fuel gas is available, gas is imported; the imported gas is measured in a meter



station before entering the unit. During normal operation, any excess fuel gas produced is

exported by a compressor system.

5. Plant and Water System

For this system, air is supplied by air compressor that is driven by steam turbine or a

motor. The air will be compressed and dried before distributing the air to the plant.

Example of company using this system is METSO Automation.

6. Nitrogen

Nitrogen gas is usually generated in the plant or purchased from a supply company. If

purchased, it is usually delivered by high-pressure pipeline. Pipeline pressures run from 300

to 600 psig. The supplier may own and operate the meter station, which forms the billing

basis for the purchase of nitrogen.

High-pressure nitrogen is delivered to the individual units in a plant (Figure 13.6-2).

The pressure is reduced at each unit to the desired working pressure, which is usually 120 to

150 psig. Nitrogen is used primarily as an inert gas for blanketing vessels and lines or for

conveying combustible materials and sometimes as a backup for instrument air.

Nitrogen hose connections are located at utility stations in the process units. These

connections are used for nitrogen only and are different from the connections used for air,

water, or steam. The nitrogen connections (Natural Standard Coupling) are welded to prevent

them from being changed to other types of fittings, namely air or water.

1. 7. Product Storage and Feed Stock Transfer



Example of company using this utilities is CCG International Inc. This company is

involving with bio-fuel. Bio-fuel must be derived from feedstock produced with much

lower life-cycle greenhouse-gas emissions than traditional fossil fuels .

7. Electrical Supply and Distribution System

The power received from electric supply companies is generally at voltage levels of 100 to

160 kV. At many plants, this is transformed down to 13.8 kV for distribution within the plant.

At the units, the 13.8 kV is stepped down to 4160 V for use on large motors (200-10,000 hp).

The 13.8 kV is also transformed to 480 V, the most common voltage in many plants, and

finally to 240 V and 120 V for heating, lighting and fractional horsepower motors.



CONCLUSION

The good plant should have good plant utilities. Every scope of plant utilities have its own

importance and if one of it is not functioning well it can effect the operation of the plant. Just

the organ in human body. If one organ is disrupt the whole function of the body is disrupt. So

the utilities should be maintained at good condition.

REFERENCES

I. http://ccgconsultinginc.com/2010sym_general.aspx

II. http://www.industrialgasplants.com/cryogenic-nitrogen-plant.html

III. http://valveproducts.metso.com/jamesbury/ApplicationReports/en/ABGP01%2012-

05.pdf

http://ccgconsultinginc.com/2010sym_general.aspx


http://www.industrialgasplants.com/cryogenic-nitrogen-plant.html


http://valveproducts.metso.com/jamesbury/ApplicationReports/en/ABGP01%2012-05.pdf









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