ENGINEERINGFORUM

Thursday, 21 February 2019

Halik February 21, 2019

Saturday, 22 February 2014

PLANT LOCATION

The geographical location of the final plant can have strong influence on the success of an industrial venture . location designing is based on the organizations long term strategies such as technological , marketing resources availability , financial strategies and scope for future expansion. the location design should be taken very carefully as any mistake may cause poor location , which could be constant source of higher cost, higher investment difficult marketing and transportation , dissatisfied and frustrated employees and consumer , frequently interruption of production abnormal wasteges delays are substandard quality etc.

the procedure for choosing a specific plant location can be presented in a series of required steps

SITE SELECTION

1. Raw materials

2.Markets

3.Transportation facilities

4. Water supply

5. Environmental consideration

6. Availability of labor

7.Taxation and legal restrictions

8.Climate

9.Property cast

10. Fire protection

11. Site characteristics

RAW MATERIALS

The source of the raw material is one of the most important factors influencing the selection of a plant site . this is practically true if large volume of raw material is consumed because location need the raw material source permits considerable reduction in transportation and storage charges . attention should be given to the purchased price of raw material also

MARKETS

The location of markets effect the cost of product distribution and the time requires for shipping proximity to the major markets is an important consideration in the selection of a plant site because the buyer usually finds it advantageous to purchase from nearby resources it should be noted that the markets are usually needed for by products as well as for major final products

WATER SUPPLY

The process industry use large quantities of water for cooling washing and steam generation as raw material. the plant therefore must be located where a dependable supply of water is available . the level of existing water table can be check by consulting the state geological survey and information on the constancy of the water table and the air round capacity of local rivers or lakes should be obtained water supply shows seasonal fluctuation it may be desirable to construct a reservoir or to drill several standby wells

ENVIRONMENTAL CONSIDERATIONS

No matter how advantageous a site location may be if a permit to build can't be obtained or the uncertainties in getting the necessary permits jeopardize the timing of the project then it may be necessary to choose another sitte , thus environmental consideration may be overall the most important site factor

AVAILABILITY OF LABOUR

The type and supply of labor in the vicinity of a proposed plant must be examined consideration should be given to prevailing pay scales restriction on numbers of hours worked per week , competing industries that can cause high turn over rates among the workers and variation in the skill and productivity of the worker

TAXATION AND LEGAL RESTRICTIONS

When considering taxes all types need to be considered , initial fees capital value cooperate personal income tax sales property tax unemployment workman compensation and nuisance tax suing the construction phase several types may be leveled t these include building permits especial fees assessment and civil connection fees

CLIMATE

If a plant is located in a cold climate cost may be increased by the necessity for construction of protective shelters around the process equipment . excessive humidity and extremes of hot and cold weather can have a serious effect on the economic operation of the plant and these factors should be examined when selecting the plant site

PROPERTY COST

Land cost in certain highly desirable petrochemical manufacturing areas can be high where as in more normal industries land costs are low where a lot of land is needed for feed and product storage the cost of the land can be significant plants also tend to locate away from areas where encroaching residential homes drive up the property cost

FIRE PROTECTION

Protection from losses by fire is important factor in selecting a plant location . in case of major fire assistance from outside fire departments should be available

fire hazards in the immediate surrounding in the plant sire must not be overlooked

SELECTION SITE

PAKISTAN REFINARY LIMITED KARACHI

REASONS

Easy approach to market

Raw material transportation cost decreases

Availability of labor

Moderate climate

Instrumentation and process control

Instrumentation and process control:

Objective of control system:

1. To ensure the stability of the process

2. To reduce the effect of external disturbances

3.To optimize the overall process

4. To keep the process variables within limit

5. To give desire purity

6. To maintain the production composition

HARD WARE ELEMENT:

To monitor and control the operation of process there are seven hardware elements as

1.Process

2.Measuring device

3. Transducer

4. Transmission lines

5.Controller

6. Final control element

7. Recorder

PROCESS

It represent the material equipment together with physical and chemical operations

MEASURING DEVICE

The instruments by which process is controlled and under required enviornrment is created for process

TRANSDUCER

It is interface between process and control system and its job is to convert the sensor signal into control system

TRANSMISSION LINES

These lines carry signal from transducer to control system . in modern systems transmission lines are mot used as they require investment in capital cost . now in modern system signal are transferred by electrical signals which don't require any transmission lines

CONTROLLER

Controller is the brain of whole plant . its objective is to compare output signal and set point and give correction to the system as required

FINAL CONTROLLE ELEMENT

Final control element work on the instruction of controller. final control element mostly is control valve

RECORDER

Recorder , records the all process variable for monitoring purpose.

GENERAL CONTROL SYSTEM

Following are the control system

1.Open loop system

2. Close loop system

3. Feed forward system

4. Feed backward system

5.Combined control system

6. Cascade control system

7.Ratio control system

MODES OF FEED BACK CONTROL SYSTEM

1.Proportional control

2. Proportional integral control

3.Proportional derivative control

4.Pid control

MEASURING DEVICES

In any chemical process we usually measure

1. Temperature

2. Pressure

3. Flow rate

4. Level

INSTRUMENTATION ON DISTILLATION COULUMN

Friday, 21 February 2014

Process Description

Reactor 1:

In commercial use two approaches predominate the air oxidation of cyclohxane process. cobalt- catalyzed oxidation and borate promoted oxidation. a third method the high peroxide process has found limited commercial use . cobalt catalyzed air oxidation of cyclohexane is the most widely used method for producing acipic acid . cyclohexane is oxidized with air at 150c to 160c and 810 to 1,013 kpa in the presence of the cobalt catalyst in a sparged reactor or multistaged column contractor.

several oxidation stages are usually necessary to avoid over oxidizing the KA mixture . cyclohexane on oxidation gives cyclohexanol and cyclohexanone (alcohol and ketone) with 20% cyclohexane remains unreacted. . unreacted (excess) oxygen is drawn out from the product

Distillation column

oxidizer effluent is distilled to recover unconverted cyclohexane then recycled to the rector feed. the resultant KA mixture may then be distilled for improved quality before being sent to the nitric acid oxidation stage. this process yields 75 yo 80 mole percent KA with a ketone to alcohol ratio of 1:2 and water is completely removed KA mixture consisting of ketonic , alcoholic group and water is the bottom product.

Heat Exchanger:

The lightly viscous mixture is then cooled from 150c-80c using water as a coolant

Reactor 2:

The second step in commercial production of acipic acid is nitric acid oxidation of the cyclohexanol & cyclohexanone mixture. the reaction proceeds as follows:

cyclohexanol+ nutric acid → adipic acid +NOX + H2O+ heat

cyclohesanone + nitric acid → acipic acid + MOX + H2O + heat

as the reaction is highly exothermic heat of reaction is usually dissipated by maintaining a high ratio (40:1)

of nitric acid to KA mixture

nitric acid 50-660% and a copper vanadium catalyst are reacted with the KA mixture in a reactor vessel at 60c to 80 and .1 o .4 Mpa . conversion yields of 92 to 96 % are attainable when using high purity KA feedstock upon reaction niteic acid is reduced to nitrogen oxides : NO2, NO, N2O and N2

This oxidation results unto the formation of 94% adilpic acid along with NOX, salicylic acid , glutaric acid water and excess HNO3

Vaccum distillation column

For enhancing the concentration of acipic acid up to 95% vacuum distillation of the mixture is done to remove water produced in the reactor 2

Crystallizer

Now moxture is sent for crystallization to achieve up to 98% pure crystals of adipic acid crystals of adipic acid are obtained with small amount of mother liquor (HNO3, Glutaric acid and salicylic acid)

CENTRIFUGE

The mother liquor is separated from crystals here by washing with water in centrifuge. for obtaining highly purre crystals of acipic acid crystals . crystals are sent to dryer

DRYER

Dryer is used to remove the water used for washing the mother liquor away from crystals in centrifuge if water removal is not done then the crystals may remain impure and cause brittleness which are not suitable for handling and transportation . up to 99% pure crystals acipic acid are obtained . this purity is needed because these crystals are going to be used in the manufacturing of very important plastic nylon