SU47402A1 - The method of separation of benzene from coke oven gas by freezing - Google Patents

Description

In the author's article “Production of benzene from direct coke-oven gas by the method of freezing (Himstroy No. 12 for 1932), the following positions are proved:

1. Freezing of benzene from gas can be performed only in the case when the gas has previously been sufficiently compressed to overcome the resistance when passing through the tubes of debenzenerators, gradually clogged with benzene crystals.

2. The most efficient use is made of the surface cooling of debenzenerator tubes when freezing gas not in the intertubular space, but inside the tubes.

3. To obtain benzene from direct coke-oven gas by freezing it without using the energy of compression and cold of the gas leaving the debenzenerators for its further separation is completely unprofitable due to the high consumption of electricity for compression and cooling of the gas.

Based on these findings, the author designed an installation for producing benzene from coke oven gas, schematically depicted in the attached

(25)

drawing. The advantages of this installation over a similar installation of Linde are:

1. Benzene freezing is performed in all four debenzene tori not inside the tube space, but inside the tubes. In this case, a more uniform operation of debenzenerators is achieved, the consumption of metal for the covers of the first pair of debenzenerators operating under almost normal pressure is reduced, and the consumption of cold for the periodic freezing of these debene gels is reduced.

2. To melt frozen benzene in the first pair of debenzene torosts, warm coke oven gas is passed inside the tubes of one already frozen debenzene torus, and not outside the tubes. Due to this, part of the benzene from the incoming gas is condensed and flows into the collector together with the molten benzene in a liquid form and the consumption of cold for the periodical freezing of casings that are not in direct contact with the warm coke oven gas is reduced.

3. For melting frozen benzene in the second pair of debenzene toros outside

the tubes of one already frozen debenzor torus are passed through warm liquid ammonia. This circumstance makes it possible to reduce the consumption of water for condensing compressed ammonia and at the same time cool ammonia more strongly than in a water condenser and, therefore, increase the cooling capacity of ammonia.

As can be seen from the attached scheme, the arrows show the direction of movement of gases and liquids, with G designating gas, GL-gaseous ammonia, HDM-liquid ammonia, SvHs-benzene (the numbers after the letters indicate the ambient temperature), compressed to 5-15 atm. Before being cleaned with all impurities except for benzene, normally cleaned, the coke oven gas is passed inside the tubes of the first already frozen debenzene torus, melts the benzene and passes inside the tubes of the second debenzene tor, cooled outside with gases leaving the coke oven gas separation unit. To freeze the residual benzene, the gas is passed inside the tubes of the fourth debenzol tor, cooled from the outside with boiling liquid ammonia, previously passed through the casing of the third debenzor tor to melt the benzene tubes frozen inside.

The valves are switched from time to time in the installation so that the coke oven gas melts the benzene in the second debenzenerator and releases the benzene in the first debenzenerator cooled by the gases leaving the coke oven gas separation unit and in the third debenzenerator cooled by boiling liquid ammonia used to melt benzene in the fourth debenzene torus.

The subject matter of the invention.

The method for freezing benzene from coke oven gas using four pairwise working coolers - heat exchangers, except that the freezing of benzene in all four refrigerators is performed inside the tubes, and the melting in the first pair by passing the direct coke oven gas also inside the tubes, and in the second steam-washing of the tubes outside with liquid ammonia.

G-25

.