摘要:
The specification describes a process for synthesizing urea. The process comprises reacting ammonia and carbon dioxide in a molar ratio of 3:1-5:1 and at a pressure of 150-250 Kg/cm.sup.2 G, subjecting the resultant reaction mixture to a stripping step using gaseous carbon dioxide at a pressure substantially equal to the urea synthesis pressure and a temperature of 195.degree.-210.degree. C. to remove unreacted ammonia and unreacted carbon dioxide contained in the reaction mixture so that the content of unreacted ammonia is lowered to 10-15% by weight. This invention ensures a high conversion ratio from carbon dioxide to urea, considerably little formation of biuret during the stripping step, and reduced consumption of high pressure steam.
摘要:
Disclosed herein is a process of synthesizing urea including reacting ammonia and carbon dioxide at a urea synthesis pressure and temperature in a urea synthesis zone, separating excess ammonia and unreacted ammonium carbamate from the thus-obtained urea synthesis melt as a gaseous mixture containing ammonia and carbon dioxide, recirculating the gaseous mixture to the urea synthesis zone, and, on the other hand, obtaining urea from an aqueous urea solution which has been obtained by separating the excess ammonia and unreacted ammonium carbamate. The above process features ingeniously combined conditions of various process steps. It produces urea using less high-pressure steam and recovers less low-pressure steam. A stripping operation making use of carbon dioxide can be effectively incorporated in the above process. The above process permits to cut the construction cost of a urea synthesis plant.
摘要:
In a synthesis of urea using ammonia in a highly excessive molar ratio, unreacted materials are decomposed and separated by subjecting the urea synthesis effluent to a stripping step using carbon dioxide at a pressure equal to the urea synthesis pressure. The thus-separated gaseous mixture of ammonia and carbon dioxide is condensed through an indirect heat exchange with an effluent stream discharged from the stripping step and lowered to a predetermined pressure level. Resulting condensation heat is used for the decomposition and separation of unreacted materials still remaining in said effluent stream. By choosing suitable operation conditions for each step of the present invention, it is possible to reduce the amount of high pressure steam to be required and to minimize the amount of low pressure steam to be recovered.
摘要:
An inert gas containing carbon dioxide and ammonia and separated from a urea synthesis effluent under urea synthesis pressures is brought into contact with an absorbent along with unreacted carbon dioxide and ammonia separated in high pressure distillation at a pressure of from 10 to 25 kg/cm.sup.2 G to absorb substantially all of the carbon dioxide and the major portion of the ammonia, and is cooled to be separated from the resulting liquid ammonia and then is discharged. The inert gas can be treated with little or no danger of explosion by the above method.
摘要:
A process is described for preparing guanidine by separating guanidine from a process stream obtained in a urea synthesis process, wherein ammonia and carbon dioxide are reacted at a high temperature and a high pressure. The process stream includes a urea synthesis effluent from a urea synthesis zone, a solution obtained by separating unreacted materials from the effluent, a concentrate of the solution or a mother liquor derived from a urea crystallization zone.
摘要:
A process for synthesizing urea in which a urea synthesis effluent obtained by reacting carbon dioxide and ammonia at urea synthesis pressures and temperatures is subjected to stripping treatment with carbon dioxide under pressures substantially equal to urea synthesis pressures to separate the unreacted carbon dioxide and ammonia contained in the urea synthesis effluent as a gaseous mixture, and a sufficient amount of said gaseous mixture to maintain the urea synthesis temperatures at a predetermined level is recycled to the urea synthesis in the gaseous state, the balance being subjected to condensation to be recycled in the liquid state to the urea synthesis.
摘要:
Carbon dioxide is reacted with a stoichiometric excess of ammonia at urea synthesis temperatures and pressures in a urea synthesis zone with the mol ratio of ammonia to carbon dioxide being in the range of from 5:1 to 12:1. The urea synthesis effluent from the urea synthesis zone is pressurized to a pressure higher than the urea synthesis pressure, and heated to a temperature higher than the urea synthesis temperature in a separation zone, wherein unreacted ammonium carbamate and excess ammonia contained in said urea synthesis effluent are separated from urea synthesis effluent in the form of a gaseous mixture of ammonia and carbon dioxide. The thus separated gaseous mixture of ammonia and carbon dioxide is recycled to said urea synthesis zone by means of the pressure difference.
摘要:
An information processing method of an information processing system including a client device functioning as a client and a server device functioning as a server which are capable of communication via a network, includes the steps of: at the server device, managing format identification information provided so as to be unique for each content data within the range of each data format, corresponding to the contents of each content; at the client device, causing execution of communication via network, for specifying a content, as to the server device; at the server device, transmitting, to the client device, format identification information correlated with a specified content in response to specification of a content via network from the client device; and at the client device, managing the received and obtained format identification information as corresponding to the specified content.
摘要:
An axle bearing assembly includes a flange, on which a wheel is mounted; a hub shaft constructed of a cylindrical portion provided on an inboard side of the flange; a bearing having an inner ring; an outer ring; and rolling elements disposed between the inner ring and the outer ring; a first sealing member fixed to an inboard side between the inner ring and the outer ring; and a removable second sealing member is fitted to the inboard side of the first sealing member. The inner ring of the bearing portion is fixed to the cylindrical portion of the hub shaft.
摘要:
An axle bearing system is provided in which even in the event that a sufficient space is not present between a bearing portion in which a fluorine seal is used in a seal portion and a hub shaft, it is possible to establish an electric conduction between an outer ring and an inner ring in an ensured fashion.There is provided an axle bearing system having a bearing portion which includes an inner ring 11, an outer ring 12 and a plurality of rolling elements 13 which are interposed between the inner ring 11 and the outer ring 12 and which is installed on a hub shaft 2 with seal portions 20a, 20b which are each formed by a slinger, a core metal and a non-conductive seal provided therebetween mounted in annular opening portions formed between the inner ring 11 and the outer ring 12, wherein a conductive body 24 is provided in the seal portion 20b so as to provide an electrical conducting state between the outer ring 12 and the inner ring 11.