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Chlorobenzene Plant

Brief Overview

A recently closed complete chlorobenzene plant is now available for immediate relocation anywhere in the world. The Chlorobenzene facility was among the leading suppliers in the Unites States. The complete plant was extremely well maintained with over $20.0 million USD in upgrades. Its major components include new columns with structured packing and a low temperature crystallizer that were both installed recently. This newly available production plant certainly presents a unique opportunity to expand businesses at a fraction of the cost of a new plant. The plant engineering documents are available and technical support provided upon special request.

Capacity:

Mono-Chlorobenzene (MCB)
- 70 million lbs/yr

Para di-Chlorobenzene (PDCB)
- 50 million lbs/yr

Ortho di-Chlorobenzene (ODCB)
- 25 million lbs/yr

Tri-Chlorobenzene (TCB)
- 18 million lbs/yr
 

Shut Down:

2002
 

Major Upgrades:

1986: $ 12 millions
1998: $ 5 millions
2002: $ 3 millions
 

Products Produced:

Mono-Chlorobenzene (MCB)
- 70 million Pounds/Year

Para di-Chlorobenzene (PDCB)
- 50 million Pounds/Year

Ortho di-Chlorobenzene (ODCB)
- 25 million Pounds/Year

Tri-Chlorobenzene (TCB)
- 18 million Pounds/Year

Documentation:

Available
 

Major Equipment:

- Columns
- Sandvik Flakers
- Powder Packaging System
- Hastelloy Recirculation Cooler and Heater
- Low–Temp Crystallizer
- Hastelloy and Monel Heat Exchangers
 

Process Description

Main Plant
Metachem products are manufactured from two raw materials, chlorine and benzene. Gaseous chlorine is sent by pipeline from a neighboring plant, Occidental Chemical Company (Oxy). This chlorine is metered as soon is entering into the plant before merging into a central header; the flow rate is controlled by a manual control valve from the Main Control Room.

After passing through an emergency block valve, the gaseous chlorine flow reaches the chlorinator reactor. Each chlorinator has one manual control valve and an emergency block valve.

Process description: Reaction System A - Main Plant
In the Main plant chlorinators (117A, 117G, 117C, 117E), the chlorine reacts with dry benzene utilizing a Lewis acid catalyst at a predetermined temperature to yield Chlorobenzene mixtures. The products of the reaction are sent to an acid and catalyst removal area, the wash system, where they are removed with water before reaching an holding tank, HT1, (material storage tank for the Wash System). The material from the holding tank is fed into the distillation system's 901/902 Columns, in order to recover the unreacted benzene from the chlorinated benzene products and to dry the fresh benzene together with the recycled benzene that will be fed to the reactors system. The water stream, with dissolved HCl and the Catalyst is sent to the Solvent Recovery System for removal of the organics from the water.

Liquid benzene is delivered into the plant by tank truck and stored in 407R. Before being reacted in the chlorinators, the moisture content of the benzene must be reduced. From the storage tank, the "wet" material is sent to the 902 Drying Column where it is vaporized.

From the top of the 902 Column, vapors pass through a condenser, which converts the vapors into a liquid. This liquid drains to the 907-reflux drum. From the 907-reflux drum, the benzene is pumped to the top of 901 and 902 Columns as reflux together with fresh benzene.

The reactor mass is fed into 901 Column where the bottom stream of benzene free Chlorobenzene are pumped into the next distillation column.

901 Column overhead vapors (containing benzene) flow through a condenser. The material condenses into a liquid, which flows to the reflux drum.

From the reflux drum, a stream of the liquid becomes reflux into the top of the 901 Column and another stream is sent into the 902 Column together with fresh benzene for drying. Free water and benzene separate into layers within the reflux drum. A boot section on the bottom of the reflux drum captures the free water, which is sent into the Accumulator.

From the Accumulator Tank, the material is sent into the wash system, to recover any organic material carried over while the water stream is sent to the Solvent Recovery System for further processing.

The 902 Column bottoms stream (consisting of dry benzene – Azeotropic distillation) is pumped into a holding tank that is the feed stock accumulator for the chlorinator reactors.

The 901/902 Distillation System and related tanks share a common vent system connecting to the Benzene Abatement System header where benzene and acidic vapors are absorbed into water and condensed, then returned to the reflux drum for processing. Remaining uncondensable material is vented through a pipeline to the main plant's caustic scrubber system and to the tail gas absorber.

Distillation System
From the 901 Column, the Chlorobenzene are pumped into the Monochlorobenzene (MCB) separator, 220R Column.

Production of MCB
The 220R Column is utilized to separate Monochlorobenzene from the other Chlorobenzene isomers. The overhead stream of this system is sent to storage and consists of saleable Monochlorobenzene. The bottom stream of the system consists of Dichlorobenzene, Trichlorobenzenes and Tetrachlorobenzenes, which is sent to the other distillation columns for further processing.

Production of Dichlorobenzene PDCB-ODCB-Eutectic

856-857 Columns
These columns are designed to produce, as an overhead stream, 97% pure PDCB, the remainder being 2% MDCB and 1% ODCB; and as a bottom stream a mixture of ODCB with Tri’s.

The two columns are combined in series that is the vapors from the 856 column are directly sent to the bottom of 857 and the liquid from the bottom of 857 is sent to the top of 856. The over-head product is collected in tank 801. From here it is sent to the falling film crystallizing unit MWB feed tank (464).

The feed material for the columns comes from 220R Column- Bottom stream. A mixture of PDCB, MDCB, ODCB and Tri's with small amount of Tetra's is sent to the Column V857 on the lowest feed point. The overhead vapors from 857 column pass to a reflux condenser in which cooling is effected by ODCB. The ODCB is pumped around a closed loop in which it also cools the overhead vapor, in another condenser, from Column C-1010. The ODCB gives up its heat in a water-cooled heat exchanger. The ODCB can also be passed through a steam-heated exchanger during start-up. The column operates at atmospheric pressure.

The two stream that leave the 856-857 Columns are: the overhead stream from 857 Column and a bottom stream from 856 Column. The overhead stream from 857 Column consists of 97% pure PDCB, the remainder being 2% MDCB and 1% ODCB is sent to the MWB Crystallizer for further purification. The bottom stream from 856 Column that consists of a mixture of ODCB with TCB's and a small amount of Tetra's is sent to the 130R column for the ODCB purification.

130R Column
This column receives the bottom stream from 856 Column and separates the ODCB from the TCB's and Tetra's. The overhead stream-ODCB is sent to the storage tank, while the bottom stream is sent to a holding tank as feed for the Tri plant.

MWB
The MWB Crystallizer is a falling film crystallization process that separates PDCB from a mixture of PDCB, ODCB, and MDCB. The unit utilizes different stages of crystallization at different temperatures to achieve the desired purity of PDCB.

There are two streams that leave this process, the pure PDCB that is sent to a storage tank, and the Eutectic steam, a mixture of PDCB, MDCB, and ODCB that is sent to an holding tank for further processing.