TH26453B - Urea preparation process - Google Patents

Abstract

DC60 Method for the preparation of urea The gas stream released during the synthesis of melamine, which contains ammonia. and mostly carbon dioxide sent back to karma How to make urea without further action And it is used there for the synthesis of urea, along with the gas stream produced by the process for high pressure melamine. which contains ammonia and carbon most of the dioxide which is sent to the high-pressure part of the urea separation machine. Method for preparing urea which the gas stream released during melamine synthesis which contains ammonia and mostly carbon dioxide It was returned to the urea process without further action. and is used there for the synthesis of urea. Along with the gas stream from the process for high pressure melamine. It consists mainly of ammonium and carbon dioxide. which is sent to the high-pressure part of the urea separation machine.

Claims (15)

1. The process for preparing urea in a urea separation machine which has at least one high-pressure section, in which the process includes the feeding of gas streams (13,213,313,413,513) released from the high-pressure process for melamine production, which operates at pressures between 12.5 MPa and 80 MPa, to at least one high-pressure section of such urea separation machine, which operates at pressures between 12.5 MPa and 17.5 MPa, where such gas streams have temperatures between 160°C and 285°C and consist significantly of ammonia and carbon dioxide. 2. The process according to claim 1, to which the high-pressure section into which the gas streams (13,213,313,413,513) are fed, shall consist of at least one type of urea reactor (A), separator (B), carbamate condenser (C), pre-separator (R) installed between the reactor and separator, flash vessel (Q) installed between the separator and carbamate condenser, or tubing between them. 3. The procedure under claim 2, in which the high-pressure section consists of a high-pressure urea reactor (A) and a high-pressure separator (B), and the gas stream (413) is fed to a constant-heated pre-separator (R) which is set between the urea reactor (A) and the separator. 4. The procedure under claim 2, where the high-pressure portion of the urea separation machine includes the carbamate condenser (C), separator (B) and the pathways between them, and where the gas streams (13,513) are fed to the carbamate condenser or to the pathways between them. 5. Any of the processes under claims 1-4, in which the urea separation machinery, including the urea synthesis reactor (A) and the said urea synthesis reactor, operates at temperatures of 160°C to 220°C. 6. Any of the processes under claims 1-4, where the gas streams released from the melamine process have a temperature between 175°C and 235°C. 7. Any of the processes under claims 1-4, in which the gas streams (13,213,313,413,513) are released from the melamine process at a pressure greater than 12.5 MPa. 8. The process under claim 7, where the gas streams (13,213,313,413,513) released from the melamine process have a pressure greater than the pressure in the high-pressure section from 0 to 10 MPa. 9. The process under claim 7, where the gas streams (13,213,313,413,513) released from the melamine process have a pressure greater than the pressure in the high-pressure section from 0 to 2 MPa. 10. Urea separation machinery for urea preparation, which contains at least one high-pressure section incorporating at least one type of urea reactor (A), separator (B), carbamate condenser (C), and fluid flow paths connecting these, and a melamine gas outlet path (13,313,513) to feed the gas stream released during the high-pressure process for melamine production into the said high-pressure section, where this gas stream contains significant amounts of ammonia and carbon dioxide. 11. The machinery under claim 10, to which at least one such high-pressure section to which the gas streams (13,213,313,413,513) are fed, is further comprised of at least one type of pre-separator (R) installed between reactor (A) and separator (B), a flash vessel (Q) installed between the separator and the carbamate condenser, and the pipes between them. 12. The machine under claim 11, in which the high-pressure section is incorporated with a pre-separator (R) operating with constant heat, installed between the urea reactor (A) and the separator (B). 13. Equipment for the synthesis of urea and melamine, comprising: a urea machine including a high-pressure section containing a urea reactor (A), a separator (B), a carbamate condenser (C), and interconnected fluid pathways; a high-pressure melamine machine including a urea scrubber (K) for receiving molten urea, a melamine reactor (L), and a product chiller (P) for producing powdered melamine, and interconnected fluid pathways; and gas outlet routes (13, 313, 513) for feeding gas from at least one of the aforementioned melamine reactors (M) and urea scrubber (K) directly to the high-pressure section at or above the pressures typically found in the high-pressure section. 14. The equipment under claim 13, to which the high-pressure sections to which the gas outlets (13,213,313,413,513) are fed, shall consist of at least one type of pre-separator (R) installed between the reactor and separator, a fresh vessel (Q) installed between the separator (B) and the carbamate condenser (C), and pipes between them. 15. The device under claim 14, in which the gas outlet path (413) is operated in conjunction with a pre-separator (R) which operates with constant heat, is installed between the urea reactor (A) and the separator (B).