METHOD OF CONTROLLING AMMONIUM SULPHATE EVAPORATION PROCESSES IN PRODUCTION OF CAPROLACTAM Russian patent published in 2012 - IPC C01C1/24 B01D1/00 

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of extracting ammonium sulphate from aqueous solution and can be used in chemical and petrochemical industry. The method is realised in a system comprising a crystalliser 1, a pump 2 and an evaporator 3, while circulating the mixture with feeding and outlet of aqueous ammonium sulphate solution and juice steam, connected to each other by pipes, wherein the system further includes a flow sensor 4, a valve with a temperature sensor 9 and shut-off valves 5 on the inlet of the aqueous ammonium sulphate solution; the following components mounted on a pipe: crystalliser column 1, pump 2, circulation evaporator 3, wherein two shut-off valves 7, 8 are used to switch off the pump 2, and one shut-off valve 6 is used for natural circulation of the mixture; a steam flow sensor 10, a valve 11 and a temperature sensor 12, mounted on top and on the pipe of the circulation evaporator 3; a level sensor 13, a valve 14 and an ammonium sulphate solution concentration sensor 15, mounted on the crystalliser column 1 and on the pipe at the inlet of the container of the tapped ammonium sulphate solution 16; a pressure sensor 17 in the middle, top 18 part of the crystalliser column and a temperature sensor 19, as well as juice steam condensers 20 and steam condensate heat-exchangers 21, connected to each other by pipes; wherein the flow rate of ammonium sulphate into the circulation line is set, temperature in the circulation evaporator 3 is determined, the mixture is circulated, the level in the crystalliser column 1 is set, concentration of ammonium sulphate at the inlet of the container of the tapped solution 16 is determined and flow rate of steam and ammonium sulphate is respectively corrected by acting on the steam valve 11 and the valves for inlet 5 and outlet 15 ammonium sulphate solution. To increase efficiency and quality of ammonium sulphate, use of a high-efficiency crystalliser column with a circulation pump and evaporator is proposed. In case of breakdown of the circulation pump, there is natural circulation of the loaded ammonium sulphate mixture. Quality of ammonium sulphate is constantly monitored at the outlet of the crystalliser column.

EFFECT: invention enables to save energy resources at steps for evaporating ammonium sulphate, oximation and at subsequent steps for obtaining caprolactam, as well as obtaining concentrated ammonium sulphate, which reduces the cost of producing caprolactam.