PLANT LOCATION

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

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

Process flow diagram:

Introduction

Chapter 1: Introduction:

Adipic Acid: 

Adipic acid (AA) is one of the most important aliphatic acids with the following chemical formula; COOH(CH₂)4 COOH little of acipic acid occurs naturally but it is produced on large scale all around the world

Physical chemical properties:

Under the normal conditions (room temperature and atmospheric pressure) adipic acid is an odorless, sour tasting solid present as a white powder . the melting point of the acid is 152c . it is solublr in polar solvents the solubility of adipic acid in water grows with increasing temperature

Application of adipic acid :

Adipic acid is an important chemical intermediate the main use of AA is a manufacture of Nylon 6,6 is mainly used for production of fibers (fishing lines , tires , carpets , home furnishing and in tough fabrics for backpacks , parachutes , luggage and business cases) and of resins . Nylon resins are used in electrical connectors auto parts and items such as self-lubricating bearings gears and cams.

although the main use of adipic acid is the above written there are more ways of using acipic acid as can br seen from the figure

Production of A.A 

In 2006 the global AA capacity was around 2.8 million metric tons per year the overall growth for AA is about 3% per year but the demand is growing faster in the year 2010 it was expected ti be abiut 5-6% the most rapidly growing sector is the nylon one where during the past decade it was between 8-10% per year

Current industrial processes

Adipic acid is produced by a two step oxidation process. the first one is oxidation of cyclohexane with air ; the second one is an oxidation of 

a) A mixture of cyclohexanone/cyclohexanol (called KA oil) or

b) only of cyclohexanol with nitric acid

Oxidation of cyclohexane with air:

Cyclohexane is obtained either by the hydrogenation of benzene of from naphtha fraction in small amounts . oxidation of cyclohexane was first performed in the year 1940 by Dupont . the process is performed at temperatures between 150-180c , under the perssure of 10-20 atm , in the presence of Co or Mn organic salts . it is a two step process ; oxidation and deperoxidation step. meanwhile the former one can be done without the catalyst the latter one is always done in the presence of catalyst . the rate limiting step of the process is the synthesis of hydroperoxide its concentration is optimized by carrying out the oxidation in passivated reactors and in the absence of transition metal complexes in order to avoid the decomposition of hydroperoxide , the deperoxidation step in done in the second reactor , where the catalyst amount and reaction condition are optimized , allowing the OL/ONE ratio to be controlled . for the fact that both of the products are more reactive than the starting material . conversion of cyclohexane is kept low only about 5-7% in order to avoid consecutive reactions , the selectivity to KA oil is about 75-80% the byproducts are carboxylic acids and cyclohexylhydroperoxide. the unconverted cyclohexane is recycled

scientific design company has developed a variation of this step it consist in the addition of substantial quantities of anhydrous meta boric acid as slurry in cyclohexane to the first of a staged series of oxidation reactors . no other catalst is necessary . boric acid reacts with cyclohexanol to give a borate ester that  stabilizes the product and reduces its tendency to be oxidized further to form rither cyclohexanone or degradation products . conversion is as high as 10% and selectivity of 90% with molar ratio OL/ONE around 10 . the borate ester formed is easily hydrolysed by hot water to boric acid and cyclohexanol. after distillation a 99.5% OL/ONE mixture is obtained  

Refraction

Define refraction of light:
when light passes from one transparent medium to another, it changes speed and direction . this bending of light is called refraction

Effects of refraction:

1. whenever we open our eyes we observe the refraction of light . the lens in our eye refracts light to form image on the retina of our eye

2. refraction causes the formation of the rainbow.

3. Refraction takes place in lenses in spectacles , telescopes , magnifying glasses

Refraction in different mediums:

When light passes from air to water or glass , it bends towards the normal . the angle of incidence is greater than the angle of refraction..

When light passes from water or glass to the air it bends away from the normal . the angle of refraction is greater than the angle of incidence

Incident Ray:

The ray of light that falls on the surface of the other medium.

Refracted Ray:

The ray of light that changes its direction in the other medium.

Angle of Incidence:

The angle between the normal and the refracted ray . it is denoted by ' i '

Angle of Refraction:

The angle between the normal and the refracted ray . it is denoted by ' r '

Law of Refraction:

There are two laws of refraction.

1. The incident ray the refracted ray and the normal at the point of incidence all lie in the same plane.

2. For two particular mediums the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant

 

Radiation

Define Radiation:
The transfer of heat energy from a hot body to a cold body directly without heating the space in between the two bodies is called radiation

Example:

 When we sit in the sun or infront of a heater , we feel warm heat energy reaches us by radiation, radiation is the only type of heat transfer by which the suns energy can move to the earth because heat can not reach to earth by conduction or convection.

Good and bad radiators and absorbers of heat...?

Black surfaces are good absorbers and good radiators of heat  while shiny surfaces are bad absorbers and bad radiators of heat.

Example:

shiny teapots and utensils can keep food or tea warm for a longer time then black ones. 

shiny containers can also keep cold liquids cool for a longer time then black containers

Application of radiation of heat:

1. When we sit beside a fire , the heat of fire reaches us by radiation.

2.The black cooling fins at the back of refrigerator radiate heat quickly.

3.During hot summer days , it is advised to wear white or light coloured clothes. white colour absorbs less heat than dark colours

4.Radiation from the sun passes through the glass or plastic of green house and wars up the soil and plants . plants and soil absorb and emit radiation and increase the temperature in the green house due to which plants grow well

Convection

Q: What is convection?
Ans: The transfer of heat on which molecules of a medium move to the source of heat energy to absorb heat and then move away from it is called convection.
Q: How does convection occur?
When water is heated it expands . the expanded water has less weight than the surrounding colder water. the warmer water is pushed upward by the colder water which has more weight. the colder water is heated and then pushed upward . this upward and downward movement of water is called a convection current. the heated water is forced up and later sinks as is cools . when the colder water returns to the bottom , it is heated again.

Convection in liquids:

1: Take a beaker and fill its two-third with water. place the beaker on the stand.

2:Add some saw dist to the water.

3: Now heat the beaker as shown in the figure . note the motion of the saw dust in the water 

Convection in Gases:

1:Light a candle and place it under one of the hole in the convection box.

2:Cover the box with plastic sheet.

3:Bring a burning piece of paper/cloth near the hole other than the candle

observe the path of the smoke in the convection box.

Coduction

Q: Explain transfer of heat by conduction.
Ans: The transfer of heat through matter without the actual movement of particles from their position is called conduction
conduction occurs in solids , liquids and gases but solids usually conduct heat better than liquids or gases.
if one end of a metal spoon is heated with a flame , the other end will also get heated up after a while . the heat energy is transferred from one end of the spoon to the other without the actual movements of particles . (atoms or molecules) of the spoon.

Observing Conduction:

1.push one end of the metal rod or knitting needle into the cork. use the cork as a handle

2.Light the candle burning candle will melt and change into liquid wax. on to the rod at three different points . let the wax cool.

3. Heat the rod on the candle. note the time when the wax at three different points melt. 

Q: Good and bad conductors....?

Ans: Good Conductors.

Materials which allow heat to flow through them easily are called good conductors of heat

Examples:

solids such as metal are good conductors of heat. 

Bad conductors:

Materials which do not allow heat to flow through then easily are called bad conductors of heat or heat insulators.

Examples:

 Solids such as wood , glass , plastic , styrofoam , etc. are  bad conductors of heat.

Good Conductors	Insulators
Silver	Air
Copper	Cork
Aluminium	Giass
Iron	Plastic
mercury	wood

Isotopes and their uses.

Isotopes:

The atoms of the same element having same atomic number but different mass numbers are called isotopes.

Example:

Judrpgem jas tjree osptp[es . An atom of hydrogen may have zero , one or two neutrons in its nucleis. protium, deuterium and tritium are three isotopes of hydrogen.

Application of isotopes in fields of medicine and agriculutre.

Isotopes are of great importance in the fields of medicine and agriculture.

1. carbon-14 can be used to calculate the age of plants:

2.. Nitrogen-15 can be used to study the effects of nitrogenous fertillixers in plants:

3. Sodium-24 can be used to study circulation of blood.

4. Phosphorus-32 can be used in treatment of blood cancer and bone diseases.

5 Chromium-51 can be used to study red blood cells in patients with blood deficiency.

6. Ieon-59 can be used to study absorption of iron in human body.

7. Cobalt60 can be used in cancer treatment.

How is sodium chloride formed (Nacl)?

1: One electron transfer from sodium atom to chlorine atom. sodium atom has 1 electeon in its outermost shell .
2: after losing one electron sodium atom becomes sodium ion (Na⁺) . the chlorine atom gains one electron to become chloride ion (cl^-)
Negetive  asnd positive ions attract each other to form sodium chloride (Nacl)
Thr valency of rach element shows the number of electrons that the atom releasea or gains . find the number of electrons released or gained for each element.

Distribution of electrons in shells

Electons:

Electrons is very light particles . it has negative charge. it revolves around the nuclrus of an atom.

Shells:

The paths of movemnent of electrons around the nuclens are called shells . shells are also calld energy levels.

Shell Number	Maximum number of electrons
shell number 1 or K-shell	2n2   = 2(1) = 2
shell number 2 or L-shell	2n2   =2(2)= 4
shell number 3 or M -shell	2n2   =2(3) = 6