Aniline Process Description

ANILINE PLANT    

Technology Supplied by: M/s Dupont of U.S.A. Basic engineering is done by: M/s Chematur Engg. AB of Sweden Detailed Engineering is done by: M/s IBI Chematur, Bombay CAPACITY AT 100% PLANT LOAD: 66.66 MT/DAY

Sr. No.

Raw Materials

Design Sp. Cons. per MT of ANILINE Production.

1

CNA

0.720 MT

2

H2

0.080MT

3

Catalyst (Wet)  1. 2. 3. 

0.119 Kg

IN BUILT SAFETY FEATURE OF PLANT: The amines are a possible carcinogen that’s why special design is done in plant to protect personnel. The thickener and the spent catalyst filter are totally enclosed Surrounding Hydrogenation reactor, water sprinkler system is available for handling any emergency caused by hydrogen leakage. PROCESS DESCRIPTION:

1.1 GENERAL Most aniline is produced by reduction of nitrobenzene in various liquid and vapour phase reactions using a variety of catalyst. 1.2 INTRODUCTORY Du Pont has produced aniline from nitrobenzene by a proprietary catalysed liquid phase Hydrogenation process since 1960. The first production unit was situated in New Jersey, But is has now been dismantled. A plant at Beaumont, Texas, was started up in 1972 and is the sole Du Pont aniline production unit. 1.3 GENERAL PROCESS DESCRIPTION In Du Pont’s proprietary process, aniline and water are produced by the liquid phase, Catalytic hydrogenation of nitrobenzene with hydrogen. Nitrobenzene (NB) is fed through two stage of counter-current liquid-liquid extraction, where it is used to recover dissolved aniline from the water of reaction produced in the reaction between NB and hydrogen.

The NB from the extractors, containing small amounts recovered aniline, is preheated and fed to the bottom of the vertical, stage aniline reactor column for conversion to aniline. Aniline slurry of a precious metal on carbon catalyst, recycled water, recycled Aniline, and hydrogen is also fed to the base of the aniline reactor. Hydrogen dissolves in the liquid mixture and reacts with nitrobenzene to form aniline and water. The reactor operates at high-pressure bar g at a temperature which reaches a peak of about 215-225 C near mid-column. The heat of reaction between hydrogen and NB vaporizes most of the aniline and water and the crude products are taken overhead as vapour. A liquid side-stream is drawn from the top tray of the reactor, passes through a gas-liquid separator, and serves to recycle catalyst to the bottom of the reactor and to purge By-product tars from the system. The sidestream is cooled and a portion is passed through a catalyst thickner to remove soluble tars in a filtrate stream. All of the side-stream, except the thickener filtrate, is returned to the base of the aniline reactor. The thickener filtrate is transferred to the purge recovery column feed tank and then to the purge recovery column. This column operates under vacuum to recover aniline overhead and concentrate the tars in the column bottom. Crude aniline, containing non-reactor NB, water, and excess hydrogen, which leave the top of The reactor as vapours or gases, are cooled and condensed through a cooling train. This Cooling train consists of two waste heat boilers, which generates medium pressure steam, a set of boiler feed water pre-heaters and finally water-cooled heat exchangers. The final cooling is critical to reduce the temperature of the stream to