CN113368805A - System and method for preparing ammonia by decomposing urea - Google Patents
System and method for preparing ammonia by decomposing urea Download PDFInfo
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- CN113368805A CN113368805A CN202110631337.2A CN202110631337A CN113368805A CN 113368805 A CN113368805 A CN 113368805A CN 202110631337 A CN202110631337 A CN 202110631337A CN 113368805 A CN113368805 A CN 113368805A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/08—Preparation of ammonia from nitrogenous organic substances
- C01C1/086—Preparation of ammonia from nitrogenous organic substances from urea
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
- B01J19/0013—Controlling the temperature of the process
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/26—Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J4/00—Feed or outlet devices; Feed or outlet control devices
- B01J4/02—Feed or outlet devices; Feed or outlet control devices for feeding measured, i.e. prescribed quantities of reagents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2204/00—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices
- B01J2204/002—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices the feeding side being of particular interest
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2204/00—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices
- B01J2204/007—Aspects relating to the heat-exchange of the feed or outlet devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Analytical Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention provides a system and a method for preparing ammonia by decomposing urea, belonging to the technical field of preparing ammonia by urea.
Description
Technical Field
The invention belongs to the technical field of ammonia preparation from urea, and particularly relates to a system and a method for preparing ammonia by decomposing urea.
Background
The ammonia production reactor is a place where urea and water are chemically reacted under a high temperature condition, and the reaction product is mainly NH under a certain temperature condition3And CO2The general chemical reaction:
CO(NH2)2+H2O→2NH3+CO2
under the condition of set atomization parameters, urea solution is sprayed into the reactor through an injector, and is quickly evaporated and reacted to generate NH3The mixed gas of (1). The reaction advancement rate increases with increasing temperature; the higher the temperature, the more thorough the urea decomposition; at high temperatures to obtain high NH3The necessary conditions for conversion.
With the implementation of strict environmental protection standards and the limitation on the use of liquid ammonia, the technology of preparing ammonia gas by using urea as a raw material is increasingly applied. In the traditional technology for preparing ammonia by pyrolyzing urea, the decomposition of urea is mainly carried out in a reactor. The reactor uses the primary air provided by the air preheater and takes an electric heating device as a heat source to decompose the urea solution sprayed by the spraying system. The primary air passes through an electric heater control device to maintain the proper urea decomposition temperature, and the urea solution passes through a multi-component metering device and then is injected into the hot air through an injector.
At present, the temperature is adjusted by adopting an electric heater, and the configured electric and cable equipment has higher specification due to relatively higher electric power, so that the acquisition cost of a user is increased. In this way, after the temperature is increased to a proper temperature by adopting the electric heater, the electric heater is used for the reactor, and the electric heater needs to consume high-quality electric energy, so that the use cost of a user is increased.
Disclosure of Invention
The invention aims to provide a system and a method for preparing ammonia by decomposing urea, wherein flue gas in a boiler is used as a heat source, cold air is heated to the temperature of 400-800 ℃ by additionally arranging an internal or external heat exchanger, hot air enters a reactor after being adjusted to the proper temperature by a heater or a temperature regulator for pyrolysis reaction of urea solution, and product gas containing ammonia gas after the reaction is sent to the outside for use through an outlet of the reactor.
In order to achieve the purpose, the invention adopts the following technical scheme:
a urea decomposition ammonia production system, comprising:
the heat exchanger is used for heating the received cold air to 400-800 ℃ and converting the cold air into hot air;
the heater is used for further heating the hot air converted by the heat exchanger, the temperature regulator is used for reducing the temperature of the hot air converted by the heat exchanger through process water, and the heated or reduced hot air is sent into the reactor;
the flow regulator is used for regulating the flow of the urea solution and then sending the urea solution to the ejector;
the injector is positioned at the upper part in the reactor and is used for atomizing and injecting the urea solution into the reactor;
and the reactor is used for decomposing and hydrolyzing the urea by utilizing the heat of the hot air to generate ammonia gas.
Further, the urea undergoes decomposition and hydrolysis reactions at temperatures in the reactor of 300 ℃ and 700 ℃.
Further, the urea solution storage tank is arranged in front of the flow regulator and used for storing the urea solution.
Further, the system also comprises a dissolving tank which is arranged in front of the solution storage tank and is used for receiving the urea and the process water and dissolving the urea and the process water into the urea solution.
A method for preparing ammonia by decomposing urea comprises the following steps:
receiving cold air through a heat exchanger, heating the cold air to 400-800 ℃, and converting the cold air into hot air;
heating or cooling the hot air by a heater or a temperature regulator, and inputting the hot air into a reactor;
the flow of the urea solution is regulated through a flow regulating module and then output to an ejector;
the injector atomizes and injects the urea solution into the reactor;
the reactor receives hot air and urea solution, and the urea is decomposed and the intermediate product is hydrolyzed by utilizing the heat improved by the hot air to generate ammonia gas.
Further, dissolving urea by using process water to obtain a urea solution.
Further, if the temperature of the hot air converted by the heat exchanger does not reach a preset lower limit value, the hot air is further heated by a heater until the temperature reaches the preset lower limit value; and if the temperature of the hot air converted by the heat exchanger is higher than a preset upper limit value, controlling the process water to spray and cool to be not higher than the preset upper limit value through a temperature regulator.
Further, the urea undergoes decomposition and hydrolysis reactions at temperatures in the reactor of 300 ℃ and 700 ℃.
Further, the chemical reaction formula for urea decomposition is CO (NH)2)2→NH3+HNCO。
Further, the intermediate product is HNCO, and the chemical reaction formula of hydrolysis is HNCO + H2O→NH3+CO2。
Compared with the prior art, the invention has the following beneficial effects:
the invention heats cold air to a higher fluctuation temperature (400-. The temperature regulator uses process water as a raw material, and after the hot air is sprayed with water moderately to reduce the temperature, the temperature reaches a proper temperature for the reactor to use. The urea solution is adjusted to the required flow rate through a flow regulator, enters an injector and is injected into the reactor under certain atomization conditions. The urea solution is subjected to liquid drop evaporation rapidly under the high-temperature condition, and urea is separated out, melted, evaporated, decomposed and hydrolyzed. Wherein, because the boiler operation load changes, the flue gas temperature that the heat exchanger utilized also can change along with it, and the hot-blast temperature of cold wind after the heat exchanger heating also can fluctuate, consequently need adjust suitable temperature to the hot-blast temperature, supply the reactor to use. The urea decomposition ammonia production process integrates the heat exchanger and the temperature controller, replaces the electric heater by using the water-spraying temperature controller, only needs to adjust the water spraying amount for temperature control, and has the advantages of simple and reliable adjustment and control, simple equipment principle and less investment.
Drawings
FIG. 1 is a schematic diagram of the composition of an ammonia production system by urea decomposition according to an embodiment.
FIG. 2 is a schematic diagram of another urea decomposition ammonia production system according to an embodiment.
In the figure: 1-heat exchanger, 2-heater, 3-temperature regulator, 4-reactor, 5-dissolving tank, 6-solution storage tank, 7-flow regulator and 8-ejector.
Detailed Description
In order to make the technical solution of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
The invention discloses a urea decomposition ammonia production system, which is used for realizing a urea decomposition ammonia production method, and is structurally characterized in that a heater is not required to be installed to heat hot air under the working condition that heat exchange heat of a heat exchanger is sufficient as shown in figure 1. The heat exchanger 1 is used for heating the received cold air to 400-800 ℃ and converting the cold air into hot air. The temperature regulator 3 is used for spraying and cooling the hot air by receiving process water, regulating the temperature of the hot air and introducing the hot air into the reactor 4. The dissolving tank 5 is used for receiving urea and process water and dissolving into a urea solution. The solution tank 6 is used for storing urea solution. The flow regulator 7 is used for flow regulation of the urea solution, which is then fed to the injector 8. An injector 8 is located in the upper part of the reactor 4 for spraying urea solution into the reactor 4. The reactor 4 is used for the decomposition reaction (CO (NH)) of urea2)2→NH3+ HNCO) and hydrolysis reactions (HNCO + H2O→NH3+CO2) Ammonia gas is generated.
The invention discloses another urea decomposition ammonia production system, which is used for realizing a urea decomposition ammonia production method, and the system is structurally as shown in figure 2 and is suitable for two working conditions of sufficient or insufficient heat exchange of a heat exchanger. The system has the same components as the system, and is different from the system in that a heater 2 is arranged between a heat exchanger 1 and a temperature regulator 3, and is used for further heating hot air converted by the heat exchanger 1 when the temperature of the hot air does not reach a preset value, and then the hot air is sent into a reactor 4 through the temperature regulator 3. The heat quantity of heat exchange is insufficient when the low-load operation is carried out, the temperature of hot air after heat exchange is low, the hot air is heated by the heater 2 and then is sent into the reactor through the temperature regulator 3, and the temperature regulator 3 does not work at the moment and does not participate in temperature regulation. The heat of heat transfer is sufficient when high load operation, and the hot-blast temperature after the heat transfer is on the high side, and heater 2 is out of work this moment, and hot-blast gets into temperature regulator 3 behind heater 2, and temperature regulator 3 carries out the temperature cooling regulation through spouting into process water. That is, only one of the heater 2 and the temperature regulator 3 is in an operating state at the same time, and participates in the temperature regulation of the hot air.
The above embodiments are only intended to illustrate the technical solution of the present invention, but not to limit it, and a person skilled in the art can modify the technical solution of the present invention or substitute it with an equivalent, and the protection scope of the present invention is subject to the claims.
Claims (10)
1. A urea decomposition ammonia production system, comprising:
the heat exchanger is used for heating the received cold air to 400-800 ℃ and converting the cold air into hot air;
the heater is used for further heating the hot air converted by the heat exchanger, the temperature regulator is used for reducing the temperature of the hot air converted by the heat exchanger through process water, and the heated or reduced hot air is sent into the reactor;
the flow regulator is used for regulating the flow of the urea solution and then sending the urea solution to the ejector;
the injector is positioned at the upper part in the reactor and is used for atomizing and injecting the urea solution into the reactor;
and the reactor is used for decomposing and hydrolyzing the urea by utilizing the heat of the hot air to generate ammonia gas.
2. The system as set forth in claim 1, wherein the urea undergoes decomposition and hydrolysis reactions at a temperature of 300 ℃ and 700 ℃.
3. The system of claim 1, further comprising a solution storage tank disposed before the flow regulator for storing the urea solution.
4. The system of claim 3, further comprising a dissolving tank disposed before the solution storage tank for receiving and dissolving the urea and the process water into a urea solution.
5. A method for preparing ammonia by decomposing urea is characterized by comprising the following steps:
receiving cold air through a heat exchanger, heating the cold air to 400-800 ℃, and converting the cold air into hot air;
heating or cooling the hot air by a heater or a temperature regulator, and inputting the hot air into a reactor;
the flow of the urea solution is regulated through a flow regulating module and then output to an ejector;
the injector atomizes and injects the urea solution into the reactor;
the reactor receives hot air and urea solution, and the urea is decomposed and the intermediate product is hydrolyzed by utilizing the heat improved by the hot air to generate ammonia gas.
6. The method according to claim 5, characterized in that urea is dissolved with process water to obtain a urea solution.
7. The method of claim 5, wherein if the temperature of the hot air converted by the heat exchanger does not reach a preset lower limit value, the hot air is further heated by the heater until the preset lower limit value is reached; and if the temperature of the hot air converted by the heat exchanger is higher than a preset upper limit value, controlling the process water to spray and cool to be not higher than the preset upper limit value through a temperature regulator.
8. The method as claimed in claim 5, wherein the decomposition and hydrolysis of urea is carried out at a temperature of 300 ℃ and 700 ℃.
9. The method of claim 5, wherein the chemical reaction formula for urea decomposition is CO (NH)2)2→NH3+HNCO。
10. The method of claim 9, wherein the intermediate product is HNCO, a chemical reaction formula for hydrolysisIs HNCO + H2O→NH3+CO2。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110631337.2A CN113368805A (en) | 2021-06-07 | 2021-06-07 | System and method for preparing ammonia by decomposing urea |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110631337.2A CN113368805A (en) | 2021-06-07 | 2021-06-07 | System and method for preparing ammonia by decomposing urea |
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Citations (6)
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Effective date of registration: 20220523 Address after: 301700 No. 502, gate 1, building 16, Baihe Huayuan, Gaohe Road International City, Hexiwu Town, Wuqing District, Tianjin Applicant after: Peng Daijun Address before: Room 503, unit 1, floor 5, building 7, yard a 12, Jingsheng North 1st Street, Beijing Economic and Technological Development Zone (Tongzhou), Tongzhou District, Beijing 101102 Applicant before: Beijing future Mingneng Technology Co.,Ltd. |
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Effective date of registration: 20220920 Address after: Room 503, unit 1, floor 5, building 7, yard a 12, Jingsheng North 1st Street, Beijing Economic and Technological Development Zone (Tongzhou), Tongzhou District, Beijing 101102 Applicant after: Beijing future Mingneng Technology Co.,Ltd. Address before: 301700 No. 502, gate 1, building 16, Baihe Huayuan, Gaohe Road International City, Hexiwu Town, Wuqing District, Tianjin Applicant before: Peng Daijun |
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