PHENOL PLANT PROCESS DIAGRAM

Phenol plant

Phenol Complex consists of the following units

• Propylene Recovery Unit
• Cumene Unit
• Phenol Unit

Brief process description of each unit is given below.

Propylene Recovery Unit

The plant is designed by Engineers India Limited to produce two grade of propylene Viz. Lean propylene of 75% purity suitable for the production of Cumene and Chemical grade propylene of 95% purity.
Capacity of the plant

• Lean Propylene (75% propylene): 21840 TPA
• Chemical grade (95% propylene): 7160 TPA

The process scheme consists of two fractionation columns with the auxiliaries and equipment for the removal of COS (Carbonyl sulphide) as H2S from the hydrocarbon. The first fractionator acts as C3-C4 splitter producing 75% propylene as top product. The second fractionator functions as C3-C3 splitter producing 95% propylene as top product. Propylene from C3-C4 splitter is treated in Caustic/MEA and water washing system to remove the sulphur.

Cumene Unit

This unit is based on UOP’s Catalytic Condensation process. This processing technique utilises a solid phosphoric acid (SPA) catalyst to promote the alkylation of benzene with propylene to yield high purity Cumene (isopropyl benzene).

The overall process flow scheme consists of combining benzene with a propane – propylene mixture at select ratio prior to the reaction zone for insurance of maximum product quality and yield. This mixture is then heated and routed to the reaction zone, where the alkylation takes place over a solid phosphoric acid catalyst. The reaction zone effluent then passes through a series of fractionation columns for the rejection of non-reactants; recycle of the unreacted benzene and for the separation of the desired Cumene product from the heavier alkylated product.

Phenol Unit

This unit is based on UOP’s CUMOX process, which is a commercially established Cumene per oxidation process for the economic and efficient production of phenol and acetone.

Capacity

• Phenol : 40,000 TPA
• Acetone :24,640 TPA

The CUMOX unit has been divided into the following process section.

Evaporation Section

In this section, CHP is concentrated in two steps from approximately 25-wt % to 80-wt%.

Cleavage Section

Concentrated CHP from the evaporation section is fed into two parallel cleavage reactor circuit along with concentrated sulphuric acid catalyst. Under controlled condition of temperature and acidity, CHP is cleaved to phenol and acetone and byproducts.

Direct Neutralisation & Effluent Treatment Section

This section perform four main functions:

• Neutralisation of the acid used as catalyst in the cleavage section.
• Washing of salts from the organic phase, which results from the neutralization.
• Recovery of phenol and acetone from several effluent streams.
• Springing of phenol recovered as sodium phenate from the effluent streams.

Fractionation section

This section mainly consists of six columns to separate and purify phenol and acetone and to recover Cumene and AlphaMethylStyrene (AMS).

Hydrogenation Section

The alphamethylstyrene (AMS) is hydrogenated back to Cumene. The reaction is carried out over a fixed bed of catalyst.

Hydrogen peroxide plant

This plant is based on UHDE’s Ethyl Anthraquione process .2-Ethyl anthraquinone (2-EAQ) the effective reactive component is dissolved in mixture of solvent called working solution. It is reduced by hydrogenation using palladium catalyst in the first step and further oxidized to generate Hydrogen peroxide and spring back 2-EAQ.
The hydrogen peroxide generated is extracted from the working solution using demineralised water. The working solution is recycled back to the hydrogenator and the above - mentioned reactions are carried out repeatedly.
The weak hydrogen peroxide (35% concentration) is subjected to vacuum distillation to increase the strength to 50% or 70% as per the requirement.
A small portion of working solution prior to hydrogenation is subjected to chemical treatment to remove or control the accumulation of side reacted products.
The process flow diagram for hydrogen peroxide plant is enclosed as figure.2  

H2O2 PLANT PROCESS BLOCK DIAGRAM

Utility Section

The phenol and Hydrogen peroxide plants are provided with these service systems.

•  Steam system
•  Cooling water system
•  General utility system (Nitrogen, electricity, process water etc)
•  Hydrogen plant 1&2
•  Captive power plant for power
•  Tankage system
•  Refrigerated water for phenol plant
•  Tempered cooling water for phenol plant
•  Hot oil system for phenol plant

Effluent Treatment Plant

The effluent from different plants is collected in equalization tanks. The combined effluent is then treated by physical, chemical and biological methods.
The treated effluent conforming to the norms specified by Kerala State Pollution Control Board is only let out from the factory.

EFFLUENT TREATMENT PLANT BLOCK DIAGRAM

RAW MATERIALS

• Benzene
• Liquified Petroleum Gas (LPG)

PROCESS CONTROL SYSTEM

The plant has a DCS system (Distributed control  System )

• The  plant operations in Kochi unit are done with Distributed Control System , a class of latest state of art, where the data acquisition and control are carried  through a number of microprocessor based control units distributed functionally and geographically over the Plant. We have three independent control rooms   and DCS systems for Phenol Hydrogen Peroxide and Boiler operations.
• Apart from DCS  , independent  PLC  and Relay based interlock systems are incorporated exclusively  for the safety of the Plant.
• The Tank Level Monitoring System  "LMS"  gives the detailed stock of raw materials, finished products, and intermediate products along with various alarms , warnings and history of the  tank operations etc.
• Automatic Drum filling of Phenol and Hydrogen Peroxide gives accurate  weighment and safe operation.
• Computerized automated Truck loading system is incorporated for the loading of Phenol, Acetone, and Hydrogen Peroxide.
• Hydro carbon gas detectors  are provided at various locations of the plant and  monitored centrally to detect any hydrocarbon leak.
• Automatic Sprinkler system is provided in LPG Storage area for the safe operation of the LPG Storage.
• BOD/COD/TSS and  PH   of the final  effluent are  continuously monitored  using on line analysers  and  data is sending to CPCB .

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