SU144159A1 - Ammonia synthesis column - Google Patents

Description

Methods of using the heat of reaction in ammonia synthesis to produce water vapor are known. However, in the known methods, the heat of reaction in the synthesis of ammonia is not sufficiently used and the specific productivity of the synthesis columns is cisc.

The proposed ammonia synthesis column differs from the known ones in that the heat exchanger is made of two parts (upper and lower heat exchangers) interconnected by a pipe attached to the upper tube plate of the lower heat exchanger and serving to bring the converted gas from the upper heat exchanger to the recovery boiler and return gas in the lower heat exchanger. Thanks to this design, the utilization of the heat of reaction is improved and the productivity of the column is improved.

The drawing shows the scheme of the proposed column / synthesis of ammonia with a remote waste-heat boiler 2. The nozzle of the synthesis column consists of three main parts: the catalyst box 3, located in the upper part of the column 1, the upper preliminary heat exchanger 4 and the lower heat exchanger 5.

The main flow of circulating gas from the switchboard enters the column 1 from above, passes down the annular gap between the housing and the nozzle and enters the tubes of the lower heat exchanger 5, where it is partially heated to approximately 210-280 ° in the opposite direction by the converted gas returned to the column synthesis from a steam boiler 2.

Out of the tubes of the lower heat exchanger, the main gas enters the annular space of the upper preliminary heat exchanger № 144159-2 -

ka 4, where it is additionally heated to 310-390 ° by the converted gas flowing in the opposite direction through the tubes from the catalyst box 5. Next, the main gas passes upwards into the catalyst box through the central tube 6 with the electric heater and then, going down the annular tube 7, enters the upper part of a two-bay switch box 8, where it is mixed with cold bypass gas (using a retaining mixing grill).

The gas flow of the second cold bypass is introduced through the pipe into the collar, like the first cold bypass, through the nozzle on the upper lid with a gland seal, passes through the lid of the catalyst box and the catalyst layer into the lower part of the gas distribution box 8, into which the ends of the second heat exchanger insulated from the bottom of the second cold bypass. These tubes are evenly spaced across the cross section of the catalyst zone between the main gas tubes.

The main and bypass gases leave box 8 through their heat exchange tubes and, heated in them due to the reaction, go out into the space above the catalyst bed where they are mixed. Next, the gas stream passes down through the catalyst and reacts with the formation of ammonia. The converted gas from the catalyst box exits at 460-500 ° C and is not directed immediately to the steam recovery boiler, but first enters the tubes of the upper pre-heat exchanger, in which it is cooled to 360-400 ° due to heat exchange with the main gas going to the catalyst box. from the tubes, the converted gas is collected in a manifold under the lower tube plate of the upper heat exchanger and exits through a swivel joint into the central support tube 6, which is rigidly fixed to the upper tube plate of the lower heat exchanger 5 and pivotally rests on a two-way lens 9 at the lower head of the synthesis column.

Thus, the support tube 6 perceives the vertical load of the plumb of the entire nozzle of the synthesis column, which creates the possibility of reliable self-sealing in the hinged connection of the tube 6 and the Q lens

From the support pipe, the gas with a temperature of 310-400 ° enters the middle pipe 10 of the outlet device 11 from two coaxial pipes, is directed into the central pipe of the steam waste heat boiler 2, enters the upper gas distributor head 12 and is distributed through the coils 13. Pass through the coils and having cooled to 220-280 ° due to evaporation of water in the boiler, gas is collected in the lower collector 14 of the boiler and returned to the synthesis column through an annular gap between the outer and inner pipe 7 of the device.

Consequently, a high-pressure discharge pipe throughout its entire length washes the gas at a much lower temperature than that of the gas exiting the synthesis column to the boiler. To reduce heat transfer between the pipes of the output device, the inner thin-walled pipe is slightly insulated from the outside. Passing through the outer openings of the lens 9, the gas is directed through a freely installed return pipe 7, spun with a gland seal relative to the lower cap of the synthesis column, into the annular space of the lower heat exchanger and, cooled by heat exchange with the incoming gas up to 65-80 °, goes from the column through the side opening in the bottom cap. Next, the converted gas is directed to the water cooler-condenser, as in the usual scheme of a synthesis unit.

Subject invention

An ammonia synthesis column, consisting of a catalyst box, a distribution manifold, a tubular heat exchanger, a device for venting the converted gas to a waste-heat boiler, which, in order to better utilize the reaction heat and increase the productivity of the column, the heat exchanger is made of two parts, the upper and lower heat exchangers, interconnected by a pipe, bonded to the upper tube plate of the lower heat exchanger and Serving for the output of the converted gas from the upper heat exchanger to the body heat recovery and return gas to the lower heat exchanger.

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