Carbon dioxide purifying and refrigerating system

Abstract

The utility model provides a carbon dioxide purifying and refrigerating system, which relates to the technical field of gas purification, and is characterized in that an ammonia vaporizer is additionally arranged, so that when the flow of a compression and purification system is lower, the amount of ammonia gas generated by the ammonia vaporizer is controlled by a regulating valve to meet the lowest operation condition of an ammonia compressor unit; when the yield of carbon dioxide in the system is increased, the ammonia compressor unit operates in the optimal working condition state through the change of the opening degree of the adjusting valve. Due to the fact that the amount of carbon dioxide captured by an amine method system and a membrane method system of a carbon capture system changes along with changes of group loads and coal types, and the situation that the output of the carbon dioxide fluctuates due to switching of standby equipment exists, the anti-interference capacity and the redundancy capacity of an ammonia refrigeration system are improved after optimization, the ammonia refrigeration system is suitable for external refrigeration gas with different yields, and the energy consumption is reduced. Starting and stopping times of important rotating machines are reduced, and reliability of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of gas purification, in particular to a carbon dioxide purification refrigeration system. Background Art

[0002] Currently, there are two main sources of carbon dioxide-rich gas available for industrial recycling: natural carbon dioxide and industrial byproduct gas. In the past, carbon dioxide was primarily used as a chemical feedstock, refrigerant, inert medium, solvent, food additive, and pressure source. With the advancement of science and technology, high-purity carbon dioxide with a purity of 99.999% has become widely used across various sectors of the national economy, primarily in the laser, electronics, metal cutting, supercritical extraction, reactor gas cooling, and scientific research fields. Recently, demand has surged due to the large quantities of high-purity carbon dioxide used as a cleaning agent in the production of light-emitting diodes and flat-panel displays.

[0003] In the existing process of carbon dioxide liquefaction and purification, the ammonia refrigeration system exchanges heat with carbon dioxide, and the liquid ammonia is vaporized through the carbon dioxide liquefaction process. After vaporization, the ammonia enters the ammonia compressor unit for liquefaction, thus forming a cycle.

[0004] However, when the carbon dioxide flow rate is low, the refrigeration load of the ammonia system is low, and the amount of liquid ammonia vaporized is insufficient to meet the minimum operating conditions of the ammonia compressor unit, causing the ammonia compressor unit to trip and the system to be unable to operate continuously. Utility Model Content

[0005] In view of this, the purpose of the present invention is to provide a carbon dioxide purification refrigeration system to solve the technical problem in the prior art that when the carbon dioxide flow rate is low, the refrigeration load of the ammonia system is low, the amount of liquid ammonia vaporized is insufficient to meet the minimum operating conditions of the ammonia compressor unit, resulting in the ammonia compressor unit tripping and the system being unable to operate continuously.

[0006] In order to achieve the above-mentioned objectives, the present invention provides a carbon dioxide purification refrigeration system, including a carbon dioxide purification refrigeration passage and an ammonia cooling passage, the carbon dioxide purification refrigeration passage is provided with a plate liquefier, a plate reboiler and a plate subcooler connected in sequence, the ammonia cooling passage is provided with an ammonia compressor unit, an evaporative condenser and an ammonia storage device connected in sequence, the ammonia storage device is connected and communicated with the plate liquefier and the plate subcooler, the plate liquefier is connected and communicated with the ammonia compressor unit, and an ammonia vaporizer is provided between the plate subcooler and the ammonia compressor unit.

[0007] According to an optional embodiment, the ammonia storage device is connected to and communicates with the plate reboiler.

[0008] According to an optional embodiment, the ammonia compressor unit includes an ammonia compressor, and the plate-type liquefier is connected to and communicates with the ammonia compressor unit.

[0009] According to an optional embodiment, an ammonia-liquid separator is provided on the input channel of the ammonia compressor.

[0010] According to an optional embodiment, a distillation tower is provided between the plate-type liquefier and the plate-type reboiler.

[0011] According to an optional embodiment, the compressor unit includes an economizer, the inlet of the economizer is connected and communicated with the ammonia storage tank, and the outlet of the economizer is simultaneously connected and communicated with the plate liquefier, the distillation tower and the plate subcooler.

[0012] According to an optional embodiment, an ammonia liquid level control valve is provided on the channel connecting the plate subcooler and the economizer.

[0013] According to an optional embodiment, the ammonia compression unit includes an oil cooler, and the oil cooler is connected to and communicates with the evaporative condenser.

[0014] According to an optional embodiment, a throttle valve is provided on the input channel of the ammonia vaporizer.

[0015] According to an optional embodiment, a shut-off valve is provided on the output channel of the ammonia vaporizer.

[0016] The carbon dioxide purification refrigeration system provided by the utility model has the following technical effects:

[0017] This CO2 purification refrigeration system incorporates an ammonia vaporizer. When the compression and purification system flow rate is low, the amount of ammonia produced by the vaporizer is controlled by a regulating valve to meet the minimum operating conditions of the ammonia compressor unit. When CO2 production in the system increases, the valve opening is adjusted to maintain optimal operation of the compressor unit. Because the amount of CO2 captured by amine and membrane carbon capture systems varies with unit load and coal type, and CO2 production fluctuates due to backup equipment switching, optimization will enhance the ammonia refrigeration system's anti-interference and fault redundancy capabilities, adapt to varying external refrigeration gas production demands, reduce the number of starts and stops during critical transitions, and improve system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1This is a flow chart of the utility model carbon dioxide purification refrigeration system.

[0020] in, Figure 1 :

[0021] 1. Plate liquefier; 2. Distillation tower; 3. Plate reboiler; 4. Plate subcooler; 5. Ammonia compressor unit; 51. Ammonia compressor; 52. Economizer; 53. Oil cooler; 6. Evaporative condenser; 7. Ammonia storage tank; 8. Ammonia-liquid separator; 9. Ammonia vaporizer. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution, and advantages of the present invention more clear, the technical solution of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] The following is combined with specific Figure 1 A preferred embodiment of the carbon dioxide purification refrigeration system of the present invention is described in detail.

[0024] This carbon dioxide purification refrigeration system includes a carbon dioxide purification refrigeration passage and an ammonia cooling passage. The carbon dioxide purification refrigeration passage is provided with a plate liquefier 1, a plate reboiler 3 and a plate subcooler 4 connected in sequence. The ammonia cooling passage is provided with an ammonia compressor unit 5, an evaporative condenser 6 and an ammonia storage device 7 connected in sequence. An ammonia-liquid separator 8 is provided on the input channel of the ammonia compressor 51. The ammonia storage device 7 is connected and communicated with the plate liquefier 1 and the plate subcooler 4, the ammonia storage device 7 is connected and communicated with the plate reboiler 3, and the plate liquefier 1 is connected and communicated with the ammonia compressor unit 5.

[0025] The ammonia compressor unit 5 includes an ammonia compressor 51, an economizer 52 and an oil cooler 53. The oil cooler 53 is also connected to and communicated with the evaporative condenser 6. The plate liquefier 1 is connected to and communicated with the ammonia compressor 61. A distillation tower 2 is provided between the plate liquefier 1 and the plate reboiler 3. The inlet of the economizer 52 is connected to and communicated with the ammonia storage tank 7. The outlet of the economizer 52 is simultaneously connected to and communicated with the plate liquefier 1, the distillation tower 2 and the plate subcooler 4. An ammonia liquid level control valve is provided on the channel connecting the plate subcooler 4 and the economizer 52.

[0026] An ammonia vaporizer 9 is provided between the plate subcooler 4 and the ammonia compressor unit 5 . A throttle valve is provided on the input channel of the ammonia vaporizer 9 , and a stop valve is provided on the output channel of the ammonia vaporizer 9 .

[0027] The carbon dioxide purification refrigeration system of the utility model increases the refrigeration load by adding an ammonia vaporizer 9, increases the heat source input, and improves the ammonia liquid gasification rate, thereby realizing the ammonia refrigeration system at low load (inlet carbon dioxide flow rate is 0Nm 3 / h) under stable operation conditions.

[0028] Carbon dioxide liquefaction and distillation process:

[0029] Gaseous carbon dioxide, compressed to a pressure of 2.5 MPa, enters plate liquefier 1. It is cooled to below -20°C by the evaporating ammonia in the tubes, condensing into liquid carbon dioxide before entering distillation tower 2. Within distillation tower 2, the liquid carbon dioxide sinks while impure gases rise and exit the top. The liquid carbon dioxide is distilled to remove non-condensable gases from the feed gas stream and enters plate reboiler 3 at the bottom of the tower. In plate reboiler 3, the liquid carbon dioxide in the shell side exchanges heat with the high-pressure, ambient-temperature ammonia gas in the tube side, evaporating again. This second evaporation of non-condensable gases into the tower, leaving the remaining liquid carbon dioxide enters plate subcooler 4, where it is further cooled by the low-pressure, low-temperature ammonia liquid in the tube side, reaching an outlet temperature of approximately -23°C. The heat source for plate reboiler 3 is gaseous ammonia extracted from the upper portion of the refrigeration system's ammonia reservoir 7, while the cooling source for plate liquefier 1 and plate subcooler 4 is throttled liquid ammonia.

[0030] Ammonia refrigeration process:

[0031] Low-pressure, low-temperature gaseous ammonia is sucked out from the top of the plate liquefier 1, the distillation tower 2 and the plate subcooler 4 by the ammonia compressor 51, and after the liquid ammonia that may be carried out is separated by the ammonia-liquid separator 8, it enters the ammonia compressor 51 for pressurization, and obtains high-pressure, high-temperature gaseous ammonia after coming out from the exhaust port of the high-pressure ammonia compressor 51. It then enters the evaporative condenser 6 to exchange heat with cooling water to obtain high-pressure, room-temperature liquid ammonia, and then enters the ammonia storage 7 for storage. The high-pressure, room-temperature liquid ammonia in the ammonia storage 7 will be discharged from the liquid outlet according to the pressure difference, and enter the economizer 52 for cooling again before being discharged. It enters the liquefaction and distillation system, and after throttling and pressure reduction by the automatic regulating valves before the liquid ammonia inlets of each device, low-pressure, low-temperature liquid ammonia is obtained. It then enters the plate liquefier 1, the distillation tower 2 and the plate subcooler 4 to evaporate and absorb heat in the raw gas. The evaporated low-pressure, low-temperature gaseous ammonia is sucked out by the ammonia compressor 51 again, forming a closed cycle, thereby achieving the purpose of liquefying carbon dioxide.

[0032] The utility model increases the refrigeration load by adding a vaporizer, increases the heat source input, and improves the ammonia liquid gasification rate, thereby achieving the ammonia refrigeration system at low load (inlet carbon dioxide flow rate is 0Nm 3 / h) under stable operation conditions.

[0033] In the description of the present invention, it should be noted that, unless otherwise specified, "plurality" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended solely for the convenience of describing the present invention and to simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this utility model depending on the specific circumstances.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A carbon dioxide purification refrigeration system, characterized in that: It includes a carbon dioxide purification refrigeration passage and an ammonia cooling passage. The carbon dioxide purification refrigeration passage is provided with a plate liquefier, a plate reboiler and a plate subcooler connected in sequence. The ammonia cooling passage is provided with an ammonia compressor unit, an evaporative condenser and an ammonia storage device connected in sequence. The ammonia storage device is connected and communicated with the plate liquefier and the plate subcooler. The plate liquefier is connected and communicated with the ammonia compressor unit. An ammonia vaporizer is provided between the plate subcooler and the ammonia compressor unit.

2. The carbon dioxide purification refrigeration system according to claim 1, characterized in that: The ammonia storage device is connected to and communicates with the plate reboiler.

3. The carbon dioxide purification refrigeration system according to claim 1, characterized in that: The ammonia compressor unit includes an ammonia compressor, and the plate-type liquefier is connected to and communicates with the ammonia compressor unit.

4. The carbon dioxide purification refrigeration system according to claim 3, characterized in that: An ammonia-liquid separator is provided on the input channel of the ammonia compressor.

5. The carbon dioxide purification refrigeration system according to claim 3, characterized in that: A distillation tower is provided between the plate-type liquefier and the plate-type reboiler.

6. The carbon dioxide purification refrigeration system according to claim 5, characterized in that: The compressor unit includes an economizer, the inlet of the economizer is connected and communicated with the ammonia storage device, and the outlet of the economizer is simultaneously connected and communicated with the plate liquefier, the distillation tower and the plate supercooler.

7. The carbon dioxide purification refrigeration system according to claim 6, characterized in that: An ammonia liquid level control valve is provided on the passage connecting the plate-type supercooler and the economizer.

8. The carbon dioxide purification refrigeration system according to claim 3, characterized in that: The ammonia compression unit includes an oil cooler, which is connected to and communicates with the evaporative condenser.

9. The carbon dioxide purification refrigeration system according to claim 1, characterized in that: A throttle valve is provided on the input channel of the ammonia vaporizer.

10. The carbon dioxide purification refrigeration system according to claim 1, characterized in that: A stop valve is provided on the output channel of the ammonia vaporizer.

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