Toyo Engineering Corporation

Mitsui Toatsu Chemicals, Incorporated

Kabushiki Kaisha Toshiba

K.e.m. Corporation

Hidetsugu Fujii

Hiroshi Ono

Shigeru Inoue

Yasuhiko Kojima

Haruyuki Morikawa

Akito Fukui

Kazuya Yamada

Kazuaki Nakagawa

Tetsuzo Honda

Yukuo Katayama

Yuzuru Yanagisawa

Keiji Murata

Kimikazu Kido

Katsuya Uehara

Yoshikazu Hagiwara

Suguru Watanabe

Mitsutoshi Hamamura

Yasuhito Sakakibara

Fumitake Watanabe

A reformer for reacting a raw material gas to be reformed, with an oxidizing agent gas and a reforming agent gas in the presence of an oxidation catalyst and a reforming catalyst to obtain a hydrogen-containing gas, including: a set of catalyst layers consisting of an oxidation catalyst layer and a reforming catalyst layer, and two or more inlets for feeding the oxidizing agent gas to the oxidation catalyst and/or the reforming catalyst in plural stages. The reformer can produce a hydrogen-containing gas without forming a combustion region of a temperature of as high as one thousand and several hundreds centigrade and can be manufactured at a low cost.

Reformer

A fuel reforming method includes the step of supplying carbon-containing fuel and steam to a reactor filled with a fuel reforming catalyst and a COabsorbent and discharging CO, and setting the absorbent at an absorption temperature, thereby converting the carbon-containing fuel into reformed fuel, and separating COfrom the reformed fuel, the step of obtaining a product gas by oxidizing a portion of the reformed fuel and/or the carbon-containing fuel with an oxidizer, and heating the absorbent with this product gas to a regeneration temperature, thereby regenerating the absorbent and storing heat in this absorbent, and the step of supplying the carbon-containing fuel and steam to the reactor, thereby cooling, to the absorption temperature, the absorbent heated to the regeneration temperature, and converting the carbon-containing fuel into reformed fuel by heat energy stored in the COabsorbent. An apparatus for the method is also disclosed.

Fuel reforming method and system

There is disclosed an improved, energy-saving granulation method, wherein use is made of a granulator (,) having a bottom floor (,) of a granulation section whose bottom is a perforated plate, an upper air feed pipe (,) for feeding air for fluidization to the bottom floor of the granulation section, a lower air feed pipe (,), air feed pipes (,) branched from the lower air feed pipe for jetting air into the granulation section, and jetting nozzles (,) provided at the centers of the air outlets for jetting a molten raw material; which involves the steps of jetting a molten raw material from the jetting nozzles to approximately spherical nuclei in the granulation section, which have been fed after the particle diameter has been caused to be an average particle diameter of 0.4 to 3.0 mm, to form granules. There is also disclosed an improved granulator.

Method for granulation and granulator

A vertical condenser is installed on or above a urea synthesis column to condense the mixed gas from the stripper by bringing it into contact with an absorption medium under cooling. A first down pipe for making the top part of the condenser communicate with the bottom part of the synthesis column is provided to allow the resultant condensate to flow down to the bottom part of the synthesis column by gravity. The condensate is subjected to urea synthesis together with feed ammonia or a part of feed carbon dioxide supplied thereto. The urea synthesis solution thus formed is introduced into the stripper by gravity through a second down pipe having an opening in the top part of the synthesis column. Unreacted ammonia and carbon dioxide are separated as the aforesaid mixed gas by the rest of the feed carbon dioxide and introduced into the bottom part of the aforesaid condenser so as to be condensed. Alternatively, the condensate from the vertical condenser is sucked by means of an ejector using preheated feed liquid ammonia as the driving fluid, so that it is introduced into the bottom part of the urea synthesis column and is subjected to urea synthesis.

Urea synthesis apparatus

Process for the synthesis of urea and equipment therefor

Process for preparing granular urea

Urea synthesis process and apparatus therefor

Disclosed herein is a method of utilizing inert gases, which are introduced as impurities in the feed raw materials for the synthesis of urea and also as an anti-corrosion agent into a urea process, as a stripping agent of unreacted materials in one or more of the below-mentioned separation steps, in a urea process in which: urea is synthesized from ammonia and carbon dioxide in the presence of an excess ammonia; unreacted materials including the excess ammonia are separated from the resulting urea synthesis solution as gaseous mixtures of ammonia and carbon dioxide successively at a plurality of pressure levels; the gaseous mixtures thus-separated are absorbed in solvents or condensed at the corresponding pressure levels; and the solutions or condensates thus-formed are circulated to the urea synthesis step. By this method, the separation efficiency of the unreacted materials is improved in the lower pressure separation steps, which eventually results in the improvement in the unit consumption of steam and the size reduction in some of the lower pressure equipments in the urea process.

Process for producing urea

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.

Process for synthesizing urea

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.

Synthesis of urea

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.

In a process in which a urea synthesis effluent obtained by reacting ammonia with carbon dioxide is subjected to a stripping step of bringing the urea synthesis effluent into countercurrent contact with carbon dioxide under heating to obtain an aqueous urea solution containing a small amount of ammonia and ammonium carbamate, the improvement comprises first bringing the urea synthesis effluent is into contact with a separated gas evolved in the stripping step under adiabatic conditions or with a little cooling. The use of the above process enables a reduction in size of the stripper and a recovery of the high pressure steam without keeping the ammonia to carbon dioxide molar ratio lower than that of the conventional method.

Growing community of inventors

Chiba, Japan

Hidetsugu Fujii