CHEMICAL PROCESS INDUSTRIES - I

ChE 506

DEPT. OF CHEMICAL ENGG. 10/Che/16 : Bipin Sharma 10/Che/17 : Vishal Rao 10/Che/18 : Annoy Roy 10/Che/19 : Riki Mandol 10/Che/20 : Koustav Ghosh 10/Che/22 : Md Dilshad 10/Che/23 : Pradeep Singh 10/Che/24 : Ravi Prakash Shiromani

Presented by:

Equipment & materials of construction in manufacturing of HCl

Hydrochloric acid(HCl) Industrial Name:-Muriatic acid

Hydrochloric acid is a clear,

colorless solution of hydrogen chloride (HCl) in water. It

is a highly corrosive, strong mineral acid

Material of construction:

FRP, PVC, HDPE and/or rubber are the materials of choice for storage tanks.

Metering pumps and other equipment that comes in contact with concentrated solutions of Hydrochloric Acid (Muriatic Acid)must also be constructed of acid resistant materials such as PVC, rubber, Teflon, ceramic and Hastolly C.

No wetted parts should contain any metals such as carbon steel, stainless steel, brass or aluminum.

Material of construction:

Rigid piping-

Schedule flanged poly vinyl chloride(PVC), polyethylene, CPVC, FRP, fluorocarbon or acid resistant rubber lined pipe, used for rigid piping.

Flexible piping-

Flexible hose lined with acid resistant rubber, cross linked polyethylene or fluorocarbon lining is used.

Valves-

The valves must be made of acid resistant material (Teflon, Saran, Kynar, FRP, PVC, ceramic or graphite). Quarter turn PVC flanged ball bulb are widely used.

Material of construction:

Gasket-

The gasket are made of Teflon, Viton fluoroelastomer, EPR, PTFE or Kynar .

Level control-

Level control system should be protected with a diaphragm made of Viton, Teflon or Tantalum.

Equipment in HCl plant:

HCl can be produced in 3 major processes:

1. Chlorination process

2. Reacting salt & sulfuric acid

3. Combustion of Chlorine & Hydrogen

Chlorination:

1. HCl is a by product in chlorination of hydrocarbons.

Reacting salt & Sulfuric acid:

1. Furnace to roast Salt & 76% Sulfuric acid.

2. Cooler, Cooler absorber to separate HCl from highly corrosive mixture of HCl and water.

3. Coke tower to separate suspension from HCl.

Synthesis:

1. Water jacketed combustion chamber for burning of chlorine.

2. Burner for supplying heat & a flame arrestor to prevent flame to reach the pure hydrogen.

3. Karbate cooler for cooling the produced gas.

4. Cooler absorber & tail gas scrubber for making the acid from HCl gas.

Comparison of Solvay & modified Solvay process

SOLVAY PROCESS OUTLINE:

Sodium carbonate (soda ash) is commercially prepared by the Solvay process, which makes use of the fact that sodium bicarbonate is less soluble in cold water than sodium chloride.

The raw materials reqd. for the process includes sodium chloride, limestone and gaseous ammonia.

Chemical interrelations of the Solvay process

Flow chart of solvay process:

Advantages of Solvay process: Can use low-grade brine Less electric power Less corrosion problems No co-products to dispose of Does not require ammonia plant investment

Disadvantages of Solvay process: Higher salt consumption Higher investment in ammonia recovery unit verses crystallization

units for ammonium chloride Waste disposal of calcium chloride brine stream More steam consumption Higher capacity plant for economic break-even operation With current fertilizer shortage, all of the ammonium chloride will be

used as a mixed chemical fertilizer ingredient, so co-product disposal no problem.

Modified Solvay process: This process was developed by Chinese chemist Hou Debeng. Here calcium chloride is replaced by ammonium chloride ( NH4Cl). Instead of treating the remaining Calcium Chloride solution with lime, Carbon Dioxide and Ammonia is added to the solution until the solution is saturated at 40oC then cooled to 10oC, causing the ammonia chloride to be removed by filtration. The ammonium chloride is then recycled to be reused in the production of sodium carbonate.

Advantages of modified Solvay process : Replaces calcium chloride as a by-product with the ammonium

chloride, which can be recycled to be reused in the process, refined and used as a fertilizer.

Eliminates the need for waste beds and other disposal methods to take place, as the by-products can be used in other productions.

Much more economical and environmentally friendly than both the Le Blanc and the original Solvay processes.

As ammonium chloride is more useful than calcium chloride, it is more economically beneficial for Solvay plants to use Hou's Process in their plants.

Disadvantages of modified Solvay process: More expensive than the Solvay Process. Requires existing machinery to be replaced or modified.

Solvay Process Modified Solvay Process Blanc Process

By-products Calcium chloride - relatively useless, most

of it needs to be disposed of.

Ammonium chloride - very useful in

the production of fertilisers. It can

be recycled to re-use ammonia.

Hydrogen chloride gas

and calcium sulfide

Thermal Pollution Heat is released and absorbed into water Heat is released and absorbed into

water

Heat is released and absorbed into water

Air Pollution Ammonia gas (toxic), however this is

reused so loss is minimal

Ammonia gas (toxic), however this is

reused so loss is minimal.

Hydrogen chloride gas (highly acidic).

Cannot be reused, must be stored.

Energy Consumption Relatively low, highest temperature

required is 300oC. Other reactions take

place at +40oC.

Lower than Solvay Process, highest

temperature required is 300oC,

however other reactions take places at

about room temperature.

Very high. Coal oxides at 1000oC. Other

reactions take place at around 300oC.

Water Use Large amounts of water are needed to

keep machine parts cool. Water can be

cooled and re-used.

Large amounts of water are required to

keep machine parts cool. Water can be

cooled and re-used.

Larger amounts of water are needed to

keep machine parts cool. Water can be

cooled and re-used.

Comparison between the two processes:-

Solvay Process Modified Solvay Process

By-products Calcium chloride - relatively useless,

most of it needs to be disposed of.

Ammonium chloride - very useful in

the production of fertilisers. It can

be recycled to re-use ammonia.

Thermal Pollution Heat is released and absorbed into

water

Heat is released and absorbed into

water

Air Pollution Ammonia gas (toxic), however this is

reused so loss is minimal

Ammonia gas (toxic), however this is

reused so loss is minimal.

Energy Consumption Relatively low, highest temperature

required is 300oC. Other reactions take

place at +40oC.

Lower than Solvay Process, highest

temperature required is 300oC,

however other reactions take places at

about room temperature.

Water Use Large amounts of water are needed to

keep machine parts cool. Water can be

cooled and re-used.

Large amounts of water are required to

keep machine parts cool. Water can be

cooled and re-used.

Reference

Shreves Chemical Process Industries by George T. Austin.

Wikipedia.

Class notes.

Outlines of Chemical Technology - Dryden