CN109595878B - Method for co-producing liquid carbon dioxide by synthetic ammonia and urea - Google Patents

Method for co-producing liquid carbon dioxide by synthetic ammonia and urea Download PDF

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CN109595878B
CN109595878B CN201811504776.1A CN201811504776A CN109595878B CN 109595878 B CN109595878 B CN 109595878B CN 201811504776 A CN201811504776 A CN 201811504776A CN 109595878 B CN109595878 B CN 109595878B
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carbon dioxide
ammonia
liquid
gas
urea
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CN109595878A (en
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祁世平
王耀
高占和
黄公青
王军飞
武占东
孙建华
曹林
边亭亭
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Inner Mongolia Boda Field Chemical Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
    • F25J3/067—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/04—Preparation of ammonia by synthesis in the gas phase
    • C01C1/0405—Preparation of ammonia by synthesis in the gas phase from N2 and H2 in presence of a catalyst
    • C01C1/0488—Processes integrated with preparations of other compounds, e.g. methanol, urea or with processes for power generation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Separation Of Gases By Adsorption (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention provides a method for coproducing liquid carbon dioxide by synthetic ammonia and urea, which is a process for deriving a byproduct liquid carbon dioxide on a main process route by utilizing the spare capacity of partial equipment in a synthetic ammonia and urea production device on the basis of the existing synthetic ammonia and urea process, and mainly prepares the liquid carbon dioxide by taking out raw gas of carbon dioxide, dehydrating, condensing and other processes. The invention fully recycles the surplus carbon dioxide discharged in the process, so as to reduce the process cost and solve the problem that the carbon dioxide discharge pollutes the environment.

Description

Method for co-producing liquid carbon dioxide by synthetic ammonia and urea
Technical Field
The invention belongs to the field of synthetic ammonia and urea production, and particularly relates to recycling of surplus carbon dioxide in a synthetic ammonia and urea production process.
Background
The synthetic ammonia refers to ammonia directly synthesized by nitrogen and hydrogen under high temperature and high pressure and in the presence of a catalyst, and is a basic inorganic chemical process. In the modern chemical industry, ammonia is the main raw material for the fertilizer industry and for basic organic chemicals. As a neutral fertilizer, urea is suitable for various soils and plants. It is easy to preserve, convenient to use, and has little destructive effect on soil, and is a chemical nitrogen fertilizer with larger use amount at present. The urea is synthesized industrially by using liquid ammonia and carbon dioxide under certain conditions. Because the reaction of ammonia and carbon dioxide is a reversible reaction, the produced carbon dioxide has more surplus in the process of producing synthetic ammonia and urea by taking coal as a raw material at present, and the surplus carbon dioxide is directly discharged to the atmosphere. In a long-term production process, the emission of carbon dioxide causes environmental pollution, and meanwhile, the production cost is increased, and the economic benefit and the social benefit of enterprises are influenced. At present, an independent device is usually built for carbon dioxide recovery, and pressure swing adsorption, chemical absorption and other processes are adopted, but the investment is large, and the production and recovery cost is high. The research on a low-cost and high-efficiency carbon dioxide recovery and storage process for reducing the process cost of synthesizing ammonia and urea is of great significance.
Disclosure of Invention
The invention aims to provide a method for co-producing liquid carbon dioxide by using synthetic ammonia and urea aiming at the defects of the prior art, co-producing carbon dioxide on the basis of a synthetic ammonia and urea process, and fully recycling surplus carbon dioxide discharged in the process so as to reduce the process cost and solve the problem that the carbon dioxide discharge pollutes the environment.
The invention relates to a process for coproducing liquid carbon dioxide by ammonia synthesis and urea, which is a process for deriving a byproduct liquid carbon dioxide on a main process route by utilizing the spare capacity of partial equipment in a device for producing the ammonia synthesis and the urea on the basis of the existing ammonia synthesis and urea synthesis processes, and mainly prepares the liquid carbon dioxide by taking out raw gas of the carbon dioxide, dehydrating, condensing and the like.
The method for synthesizing ammonia and urea and coproducing liquid carbon dioxide comprises the steps of taking desulfurized and dehydrogenated carbon dioxide from a secondary outlet of a carbon dioxide compressor of a urea synthesis device as raw material gas, dehydrating the raw material gas by pressure swing adsorption and temperature swing adsorption in sequence, and condensing to obtain a liquid carbon dioxide product.
Further, in the temperature swing adsorption process, the regenerated gas is the regenerated nitrogen of the molecular sieve of the synthetic ammonia liquid nitrogen washing device, the adsorbent adsorbing the moisture in the raw material gas is desorbed again by utilizing hot regenerated nitrogen, so that the desorbed adsorbent enters the next round of adsorption, and the nitrogen is discharged.
Furthermore, in the temperature swing adsorption process, the dew point of the dehydrated feed gas is less than-70 ℃.
Further, the condensing step is to condense and liquefy the carbon dioxide by gasifying liquid ammonia in a refrigeration system of the synthetic ammonia device.
Carbon dioxide liquefaction is a typical physical liquefaction process and does not involve any chemical reactions. At a certain pressure, when the temperature drops to the dew point of the pressure corresponding to carbon dioxide, the gaseous carbon dioxide starts to liquefy until liquefaction is complete. The invention relies on the original ammonia and urea synthesis process, adopts liquid ammonia as a cold source, and removes the condensation heat of carbon dioxide by gasifying the liquid ammonia.
And further, after the condensation process, carrying out gas-liquid separation, sending liquid carbon dioxide which meets the industrial carbon dioxide product standard into a carbon dioxide storage tank, carrying out reheating on non-condensable inert gas, then emptying, and returning the gasified ammonia gas to the first-section inlet of the ammonia compressor of the ammonia synthesis device.
Further, on the basis of the existing ammonia and urea synthesis process line, carbon dioxide recovery process equipment and a line are added to co-produce liquid carbon dioxide, wherein the carbon dioxide recovery process equipment comprises a pressure swing adsorber, a temperature swing adsorber, a heat energy recoverer, a carbon dioxide liquefier liquid level tank and a liquid carbon dioxide storage tank; a pressure swing adsorber and a temperature swing adsorber which are communicated with each other are sequentially arranged at the outlet of the two-section of a carbon dioxide compressor of the urea synthesis device, the outlet of the temperature swing adsorber is communicated with the feed gas inlet of a heat energy recoverer, the carbon dioxide gas outlet of the heat energy recoverer is communicated with the inlet of a carbon dioxide liquefier, and the outlet of the carbon dioxide liquefier is sequentially connected with a liquid level tank and a liquid carbon dioxide storage tank of the carbon dioxide liquefier; meanwhile, the heat energy recoverer and the ammonia device refrigerating system form a loop, and the carbon dioxide liquefier and the ammonia device refrigerating system form a loop.
Further, the heat energy recoverer is a heat exchanger and is used for cooling the raw material gas and part of cold air from a CO2 liquefier of the ammonia plant refrigeration system by using raw material CO2, so that cold energy is recovered. The heat energy recoverer and the carbon dioxide liquefier are connected through a pipeline to realize the process.
Further, the carbon dioxide liquefier is a U-shaped tube heat exchanger, a gaseous carbon dioxide inlet, a liquid carbon dioxide outlet, a liquid ammonia inlet and a gas ammonia outlet are formed in the U-shaped tube heat exchanger, the gaseous carbon dioxide inlet is communicated with a carbon dioxide gas outlet of the heat energy recoverer, the liquid carbon dioxide outlet is communicated with the carbon dioxide liquid level tank, liquefied carbon dioxide enters the carbon dioxide liquefier to be subjected to gas-liquid separation, the liquid ammonia inlet is communicated with the ammonia cooler, and the gas ammonia outlet is communicated with the ammonia cooler to be subjected to gas ammonia recovery.
Preferably, a pressure gauge and a liquid level meter interface are further arranged on the carbon dioxide liquefier, so that an operator can conveniently monitor the pressure of the equipment and the liquid level of the internal liquid at any time.
Gaseous CO2Exchanging heat and cold with liquid ammonia in the apparatus to remove CO2Cooling and liquefying the liquid ammonia into liquid, heating and gasifying the liquid ammonia into gas ammonia, and returning the gas ammonia to the original system.
Further, the liquid level tank of the carbon dioxide liquefier is a vertical kettle body, and gas-liquid separation is carried out by utilizing the gravity settling principle.
The process flow comprises the following steps: the desulfurized and dehydrogenated carbon dioxide raw material gas from the second-stage outlet of a carbon dioxide compressor of a urea synthesis device is dehydrated by a pressure swing absorber and a temperature swing absorber in sequence, the nitrogen is regenerated by a molecular sieve from a synthetic ammonia liquid nitrogen washing device in the temperature swing adsorption stage, the adsorbent adsorbing the moisture in the raw material gas is desorbed by utilizing hot regenerated nitrogen, so that the desorbed adsorbent enters the next round of adsorption, the nitrogen is discharged, the dehydrated carbon dioxide gas enters a heat energy recoverer, the liquid ammonia gasification from an ammonia device refrigeration system (a combined ammonia cooler, which is original equipment of the synthetic ammonia and urea process) is utilized to carry out primary cooling on the raw material carbon dioxide gas, the ammonia gasified by the liquid ammonia returns to the ammonia device refrigeration system, the raw material carbon dioxide gas after primary cooling enters a carbon dioxide liquefier, and the same as the raw material carbon dioxideCondensing and liquefying carbon dioxide by gasifying liquid ammonia from a freezing system (combined ammonia cooler) of an ammonia synthesis device to obtain gaseous CO2Performing heat exchange with liquid ammonia in a carbon dioxide liquefier to remove CO2Cooling and liquefying the liquid ammonia into liquid, heating and gasifying the liquid ammonia into gas ammonia, and sending the gas ammonia back to a refrigeration system (a first-section inlet of an ammonia press) of the original ammonia synthesis device. After the condensation process, the liquefied carbon dioxide enters a liquid level tank of a carbon dioxide liquefier for gas-liquid separation, the liquid carbon dioxide meets the standard of industrial carbon dioxide products and is sent into a carbon dioxide storage tank, and the uncondensed inert gas is directly emptied. The obtained liquid carbon dioxide product can be directly sold as a product, and can also be further refined as a raw material to obtain a food-grade carbon dioxide product with higher purity.
In actual production, the air pumping amount of a carbon dioxide compressor of the existing device is far lower than a design value, so that the surplus compression amount of the carbon dioxide compressor is utilized to recycle the emptied carbon dioxide gas (which enters pressure swing adsorption and temperature swing adsorption after being compressed by the compressor) to be used as a raw material for producing liquid carbon dioxide products, the arrangement of a compression system is saved, liquid ammonia produced by the existing device is used as a cold source for liquefaction in the liquefaction process, the liquid ammonia is generated by compression and refrigeration of the ammonia compressor of the existing device, the effective load of the existing ammonia compressor is lower than the design load, so that a refrigeration device does not need to be additionally arranged, and most of energy-consuming and acting equipment is attached to the energy expansion of. Therefore, the process saves energy, improves the effective utilization rate of equipment, increases the maximum utilization value of resources and is suitable for large-scale application in factories while obtaining pure carbon dioxide products.
The process for synthesizing ammonia and urea is the prior process and comprises the working procedures of coal water slurry gasification, CO transformation, acid gas removal, low-temperature methanol washing, gas refining, sulfur recovery, ammonia synthesis, urea synthesis, low-pressure separation recovery, absorption, analysis and the like.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention utilizes partial processes and equipment of the traditional coal synthesis ammonia and urea device, combines the carbon dioxide liquefaction process with the traditional coal synthesis ammonia and urea device, utilizes the surplus capacity of partial equipment, realizes the purpose of co-producing liquid carbon dioxide, saves energy, improves the utilization rate of the equipment and reduces the production cost.
2. The carbon dioxide recovery process constructed according to the process of the invention has the advantages of low investment, simple operation, low operating cost and greatly reduced production cost.
3. The liquefied carbon dioxide is used as a product, is convenient to store and transport, provides more ways for recycling, and is very beneficial to reducing the emission of greenhouse gases and protecting the environment.
4. The invention is further improved and perfected depending on the existing ammonia and urea synthesis process and device, is different from the traditional separately-built carbon dioxide recovery device and process, and has good safety and reliability.
5. The high-purity carbon dioxide product produced by the method can be used as a raw material for producing soda ash, can also be used as a raw material for petroleum exploitation, and can also be used as a carbon fertilizer for novel greenhouse crops, so that the application is very wide.
6. The engineering can reduce the emission of greenhouse gas CO2 by 5 ten thousand tons every year.
Drawings
FIG. 1 is a block diagram of the flow of the existing ammonia and urea synthesis process.
FIG. 2 is a block diagram of a carbon dioxide recovery process according to the present invention.
FIG. 3 is a process flow diagram of the ammonia and urea synthesis and co-production of liquid carbon dioxide in the example.
In the figure, 1-a heat energy recoverer, 2-a carbon dioxide liquefier, 3-an ammonia cooler, 4-a carbon dioxide liquefier liquid level tank, 5-a pressure swing adsorber, 6-a temperature swing adsorber, 7-a liquid titanium dioxide storage tank A, 8-a liquid titanium dioxide storage tank B, 9-a carbon dioxide loading pump A, 10-a carbon dioxide loading pump B, 11-a two-section inter-section cooler, 12-a dehydrogenation reactor, 13-a two-section separator and 14-a liquid nitrogen molecular sieve washing.
Detailed Description
The method for the co-production of liquid carbon dioxide by ammonia and urea synthesis according to the present invention is further illustrated by the following specific examples. The following description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes that can be made by the present invention as described in the specification and drawings, or directly or indirectly applied to other related arts, are intended to be encompassed by the present invention.
Example 1
Raw material coal and boiler fuel coal for producing synthetic ammonia and urea are bituminous coal of Mongolian mining company. Raw material coal is transported to a coal yard from Mongolia mining industry through an automobile, then is conveyed to 2 10000 tons of raw coal silos in a plant area through three conveying belts, and then is respectively conveyed to a coal gasification device and a thermoelectric device. Flue gas generated by bituminous coal combustion is desulfurized by an ammonia method.
Coal is used as raw material, and adopts 6.5Mpa multi-raw material slurry coal gasification technology of northwest chemical research institute, the coal water slurry is pressurized by high-pressure coal slurry pump and then is fed into gasification furnace under the condition of 6.5MPa and 1400 deg.C, under the condition of no oxygen gas the violent gasification reaction can be produced, so that the crude gas mainly containing carbon monoxide, hydrogen and carbon dioxide can be produced, after the crude gas is chilled and washed, after the ash residue is removed from the crude gas, the CO is attached to the crude gas and the sulfur-resisting transformation is blocked, and the acid gas removing process, gas refining, synthetic gas compression and freezing are intermediate product liquid ammonia produced in ammonia synthesis process, liquid ammonia and CO removed from acid2Sending to a urea plant to produce small-particle urea. KBR low-pressure ammonia synthesis technology is adopted for ammonia synthesis, and 2000+ TM super-excellent CO of Stamicarbon company is adopted for a urea plant2And (4) performing a stripping process, wherein the final product is small-particle urea. The sulfur recovery adopts a three-level Claus sulfur recovery technology.
On the basis of the process flow, carbon dioxide recovery process equipment and a circuit are added to co-produce liquid carbon dioxide, wherein the carbon dioxide recovery process equipment comprises a pressure swing absorber 5, a temperature swing absorber 6, a heat energy recoverer 1, a carbon dioxide liquefier 2, a carbon dioxide liquefier liquid level tank 4 and liquid carbon dioxide storage tanks (7, 8); a pressure swing adsorber and a temperature swing adsorber which are mutually communicated are sequentially arranged at the outlet of the two-section of a carbon dioxide compressor of the urea synthesis device, the outlet of the temperature swing adsorber is communicated with the feed gas inlet of a heat energy recoverer, the outlet of the raw material carbon dioxide gas of the heat energy recoverer is communicated with the inlet of a carbon dioxide liquefier, and the outlet of the carbon dioxide liquefier is sequentially connected with a liquid level tank and a liquid carbon dioxide storage tank of the carbon dioxide liquefier; meanwhile, the heat energy recoverer and the ammonia device refrigerating system form a loop, and the carbon dioxide liquefier and the ammonia device refrigerating system form a loop.
The heat energy recoverer is a heat exchanger, the raw material carbon dioxide gas is preliminarily cooled by utilizing liquid ammonia gasification from an ammonia device freezing system (a combined ammonia cooler which is original equipment of a synthetic ammonia and urea process), the gasified ammonia gas of the liquid ammonia is returned to the ammonia device freezing system for preliminary cooling, and meanwhile, the surplus cold quantity of the ammonia cooler is fully utilized.
The carbon dioxide liquefier is a U-shaped tube heat exchanger, a gaseous carbon dioxide inlet, a liquid carbon dioxide outlet, a liquid ammonia inlet and a gas ammonia outlet are arranged on the U-shaped tube heat exchanger, the gaseous carbon dioxide inlet is communicated with a carbon dioxide gas outlet of the heat energy recoverer, the liquid carbon dioxide outlet is communicated with the carbon dioxide liquid level tank, liquefied carbon dioxide enters the carbon dioxide liquefier to be subjected to gas-liquid separation, the liquid ammonia inlet is communicated with the ammonia cooler, and the gas ammonia outlet is communicated with the ammonia cooler to be subjected to gas ammonia recovery. A pressure gauge and a liquid level meter interface are further arranged on the carbon dioxide liquefier, so that an operator can conveniently monitor the pressure of the equipment and the liquid level of the internal liquid at any time.
The liquid level tank of the carbon dioxide liquefier is a vertical kettle body, and gas-liquid separation is carried out by utilizing the gravity settling principle.
The technological process is shown in figure 3, wherein the ammonia cooler, the two-stage intercoolers, the dehydrogenation reactor, the two-stage separator and the liquid nitrogen molecular sieve washing device are all devices on the existing ammonia and urea synthesis process line.
The temperature of the carbon dioxide gas extracted from the outlet of the second stage of the carbon dioxide compressor of the urea plant is about 36 ℃, the pressure is about 2.66MPaG, and the flow rate is as follows: 4800m3H, removing water and impurities through pressure swing adsorption and temperature swing adsorption in sequence, then entering a heat energy recoverer, and feeding the raw material gas and CO from the raw material gas2Part of cold air of the liquefier exchanges heat to feed gas CO2Cooling to recover cold. The temperature swing adsorption stage adopts a liquid nitrogen washing device from synthetic ammoniaMolecular sieve regenerated nitrogen (pressure: 0.4MPa, temperature: 205 ℃), desorbing the adsorbent adsorbed with water in the raw material gas by hot regenerated nitrogen, so that the desorbed adsorbent enters the next round of adsorption, and exhausting nitrogen and reheating exhausted inert gas.
Then, the carbon dioxide gas enters a carbon dioxide liquefier for condensation. The cold source used for condensation is liquid ammonia (pressure: 0.4MPa, temperature: 3.5 ℃) from an ammonia synthesis device, the liquid ammonia is gasified under micro-positive pressure, the gasification temperature is about 29 ℃, and the gasified liquid ammonia returns to a section of inlet of an ammonia compressor. The temperature of the condensed carbon dioxide is about-25 ℃, the condensed carbon dioxide enters a liquid level tank of a carbon dioxide liquefier to carry out gas-liquid separation, a liquid phase is sent into a carbon dioxide storage tank through self-pressure to obtain a liquid carbon dioxide product, noncondensable inert gas (the pressure is 2.3MPa) is reduced through a pressure regulating valve, and then is reheated through a heat energy recoverer and discharged to the air, and the product carbon dioxide is loaded out of the vehicle through loading pumps (9,10) for sale.

Claims (7)

1. The method for synthesizing ammonia and urea and coproducing liquid carbon dioxide is characterized by comprising the steps of sequentially arranging a pressure swing adsorber and a temperature swing adsorber which are communicated with each other at the outlet of the second section of a carbon dioxide compressor of a urea synthesizing device, taking desulfurized and dehydrogenated carbon dioxide from the outlet of the second section of the carbon dioxide compressor of the urea synthesizing device as raw material gas for coproducing liquid carbon dioxide, sequentially carrying out pressure swing adsorption and temperature swing adsorption on the raw material gas for dehydration, removing moisture and impurities, and condensing to obtain a liquid carbon dioxide product; in the temperature swing adsorption process, the regenerated gas is the regenerated nitrogen of the molecular sieve of a liquid nitrogen washing device for the synthetic ammonia, and the hot regenerated nitrogen is utilized to desorb the adsorbent which adsorbs the moisture in the raw material gas, so that the desorbed adsorbent enters the next round of adsorption, and the nitrogen is discharged; on the basis of the existing ammonia and urea synthesis process line, carbon dioxide recovery process equipment and a line are added to co-produce liquid carbon dioxide; the carbon dioxide recovery process equipment comprises a pressure swing adsorber, a temperature swing adsorber, a heat energy recoverer, a carbon dioxide liquefier liquid level tank and a liquid carbon dioxide storage tank; the outlet of the temperature-changing adsorber is communicated with the feed gas inlet of the heat energy recoverer, the carbon dioxide gas outlet of the heat energy recoverer is communicated with the inlet of the carbon dioxide liquefier, and the outlet of the carbon dioxide liquefier is sequentially connected with the liquid level tank of the carbon dioxide liquefier and the liquid carbon dioxide storage tank; meanwhile, the heat energy recoverer and the ammonia device refrigerating system form a loop, and the carbon dioxide liquefier and the ammonia device refrigerating system form a loop; the heat energy recoverer is a heat exchanger and is used for cooling raw material gas and non-condensable inert gas from a CO2 liquefier by using raw material CO2, so that cold energy is recovered.
2. The method for synthesizing ammonia and co-producing liquid carbon dioxide from urea according to claim 1,
in the temperature swing adsorption process, the dew point of the dehydrated feed gas is lower than-70 ℃.
3. The method for combined production of liquid carbon dioxide and synthetic ammonia according to claim 1, wherein the condensation process is to condense and liquefy carbon dioxide by gasifying liquid ammonia in a refrigeration system of an ammonia synthesis device.
4. The method for coproducing liquid carbon dioxide and ammonia as defined in claim 1, wherein the condensation step is followed by gas-liquid separation, the liquid carbon dioxide meets the industrial carbon dioxide product standard, the liquid carbon dioxide is sent to a carbon dioxide storage tank, the uncondensed inert gas is subjected to reheating and then discharged, and the gasified ammonia gas is returned to the ammonia compressor of the ammonia synthesis device.
5. The method for synthesizing ammonia and co-producing liquid carbon dioxide from urea as claimed in claim 1, wherein the carbon dioxide liquefier is a U-tube heat exchanger, and is provided with a gaseous carbon dioxide inlet, a liquid carbon dioxide outlet, a liquid ammonia inlet, and a gas ammonia outlet, wherein the gaseous carbon dioxide inlet is communicated with the carbon dioxide outlet of the heat energy recovery device, the liquid carbon dioxide outlet is communicated with the carbon dioxide liquid level tank, so that liquefied carbon dioxide enters the carbon dioxide liquefier for gas-liquid separation, the liquid ammonia inlet is communicated with the ammonia cooler, and the gas ammonia outlet is communicated with the ammonia cooler for gas-ammonia recovery.
6. The method for the combined production of liquid carbon dioxide and synthetic ammonia according to claim 1, wherein a pressure gauge and a liquid level meter interface are further arranged on the carbon dioxide liquefier, so that an operator can conveniently monitor the pressure of the equipment and the liquid level of the internal liquid at any time.
7. The method for synthesizing ammonia and urea and co-producing liquid carbon dioxide according to claim 1, wherein the liquid level tank of the carbon dioxide liquefier is a vertical kettle body, and gas-liquid separation is performed by using the gravity settling principle.
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CN101607708A (en) * 2009-07-27 2009-12-23 申屠晶 The co-production of technical grade and food-class liquid CO 2 and device
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