Carbon dioxide mixed gas refrigeration separation and recovery system under normal pressure

Abstract

The utility model discloses a kind of carbon dioxide mixed gas refrigeration separation recovery systems under normal pressure, it is related to combustion type flue gas carbon dioxide recycling technical field.Its separation recovery system includes ultra-low temperature CO2 separation tower and large temperature difference special temperature zone heat pump, and ultra-low temperature CO2 separation tower is connected with large temperature difference special temperature zone heat pump by ultra-low temperature cold source delivery pipe;Its separation recovery method is using large temperature difference special temperature zone heat pump to rapidly cool to below 78 ℃ below zero of flue gas or mixed gas containing carbon dioxide, carbon dioxide gas immediately becomes carbon dioxide solid (dry ice), and is separated from other gas, carbon dioxide solid is separated out, other gas is discharged, and pure carbon dioxide is obtained.The system of the utility model recycles carbon dioxide gas, simple, application equipment is less, recovery is complete, clean, and the obtained carbon dioxide is pure;The utility model can completely separate and recover carbon dioxide gas in exhaust gas, realize zero carbon emission, can convert and utilize recycled carbon dioxide, greatly reduce primary energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of carbon dioxide recovery and utilization technology in mixed gases containing carbon dioxide, particularly the recovery and utilization of carbon dioxide in combustion flue gas, and specifically to a carbon dioxide mixed gas cryogenic separation and recovery system under normal pressure. Background Technology

[0002] In recent years, a large number of research experiments have been conducted on the capture, separation, collection, storage and conversion of carbon dioxide. The main process routes are chemical adsorption, desorption, separation, collection, storage and conversion of carbon dioxide gas. However, this method has problems such as short adsorbent life, high energy consumption, difficult storage and high cost. Therefore, the capture and collection of carbon dioxide gas has not yet been widely used.

[0003] Existing invention patent CN 117679904 A discloses a method and system for recovering carbon dioxide from flue gas. The method includes the following steps: feeding flue gas into a temperature-switching adsorption tower for temperature-switching adsorption treatment to obtain a first decarbonized gas; regenerating the first adsorbent filled in the temperature-switching adsorption tower to obtain a first-stage concentrated gas; passing the first-stage concentrated gas into a pressure-switching adsorption tower for pressure-switching adsorption separation, and then desorbing the second adsorbent in the pressure-switching adsorption tower to obtain a second decarbonized gas and a second-stage concentrated gas. The system includes a temperature swing adsorption tower, a pressure swing adsorption tower, a first storage tank, and a second storage tank; the second storage tank is connected to the pressure swing adsorption device; the top of the temperature swing adsorption tower is switchably connected to the first storage tank and the second storage tank; a first heat exchanger is installed on the pipeline between the second storage tank and the top of the temperature swing adsorption tower; the bottom of the temperature swing adsorption tower is switchably connected to the first storage tank, the flue gas supply pipeline, and the second storage tank. The recovery method provided by this invention employs a two-stage coupled temperature-swing-pressure adsorption (TSA) process. After the flue gas undergoes TSA and PSA sequentially, a carbon dioxide capture rate of no less than 90% can be achieved. The flue gas first undergoes TSA, where the adsorbent in the TSA tower is regenerated using thermal energy. The regeneration process includes the following steps: high-concentration recirculating gas is introduced into the TSA tower after heating, raising the tower to the regeneration temperature and desorbing the first adsorbent to obtain a mixture of the first-stage concentrated gas and the cooled high-concentration recirculating gas; then, the first decarbonized gas or low-concentration recirculating gas is introduced into the TSA tower, cooling it to the PSA temperature to obtain a heated first decarbonized gas. Because the heating and cooling of the adsorbent in traditional TSA processes are very slow, they are more suitable for treating flue gas with low carbon dioxide concentrations. This invention, however, uses a recirculating gas thermal regeneration process to achieve rapid heating and cooling of the TSA tower, resulting in high regeneration efficiency of the first adsorbent and a regeneration time that matches the adsorption time.

[0004] However, the existing flue gas carbon dioxide recovery methods and systems mentioned above are actually physical adsorption methods. On the one hand, their technological maturity is low, and they lack large-scale technical verification experiments. Furthermore, the adsorbent is easily poisoned by harmful components in the flue gas and quickly loses its adsorption capacity. On the other hand, because the desorption capacity of the adsorbent during the pressure swing process is very limited, even if the regeneration efficiency of the adsorbent can be improved by using a circulating gas thermal regeneration process, the regeneration process of the adsorbent also makes the recovery method complicated. It is also necessary to consider the handling and replacement of adsorbent failure. In particular, the desorption process needs to be completed under vacuum conditions, which further increases the complexity of the recovery method and system, resulting in higher operating costs, larger footprint, and higher subsequent maintenance costs. This leads to high energy consumption and makes it impossible to achieve long-term stable ultra-low emissions. Summary of the Invention

[0005] To address the aforementioned technical problems, the purpose of this utility model is to provide at least one atmospheric pressure carbon dioxide mixed gas cryogenic separation and recovery system. This system not only enables simpler separation and recovery of carbon dioxide, but is also easy to operate, has high energy utilization, and, in particular, can directly complete the separation and recovery in one step under atmospheric pressure to obtain pure solid carbon dioxide, thereby achieving zero or micro-emissions of carbon dioxide.

[0006] This invention relates to a system for separating, collecting, and recovering carbon dioxide from a mixed gas containing carbon dioxide under normal pressure using the principle of physical phase change. This system is simple and easy to implement, and can be widely used in the energy field and other fields, fundamentally solving the problem of large-scale carbon dioxide emissions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a carbon dioxide mixed gas cryogenic separation and recovery system under normal pressure, comprising an ultra-low temperature CO2 separation tower and a large temperature difference special temperature zone heat pump, wherein the ultra-low temperature CO2 separation tower and the large temperature difference special temperature zone heat pump are connected through an ultra-low temperature cold source delivery pipe.

[0008] Furthermore, the ultra-low temperature CO2 separation tower is provided with a non-CO2 gas outlet at the top and a solid CO2 collection chamber at the bottom. A solid CO2 outlet is provided below the solid CO2 collection chamber. The ultra-low temperature CO2 separation tower is provided with a CO2 mixed gas inlet on one side and an ultra-low temperature cold source medium inlet and an ultra-low temperature cold source medium outlet on the other side.

[0009] Furthermore, the large temperature difference special temperature zone heat pump is provided with a high-temperature hot water inlet and a high-temperature hot water outlet at the top, a heat pump power unit on its side, and a heat pump ultra-low temperature cold source outlet and a heat pump ultra-low temperature cold source inlet at the bottom.

[0010] Furthermore, the cryogenic cold source delivery pipe includes a cryogenic liquid supply pipe and a cryogenic liquid return pipe. One end of the cryogenic liquid supply pipe is connected to the cryogenic cold source medium inlet of the separation tower, and the other end is connected to the cryogenic cold source outlet of the heat pump. One end of the cryogenic liquid return pipe is connected to the cryogenic cold source medium outlet of the separation tower, and the other end is connected to the cryogenic cold source inlet of the heat pump.

[0011] Preferably, the large temperature difference special temperature zone heat pump can quickly generate a temperature difference of over 200°C, and can directly reduce the temperature to below -80°C under normal pressure in one step, while obtaining a high temperature of over 100°C, which facilitates heat recovery and utilization.

[0012] Preferably, the heat pump for the special temperature zone with large temperature difference adopts a Stirling heat pump unit or a reverse Brayton cycle heat pump unit.

[0013] Preferably, the ultra-low temperature CO2 separation tower has a uniform ultra-low temperature environment to ensure that the CO2 gas is completely and thoroughly cooled to below -80°C, and that no CO2 gas escapes, thus ensuring complete separation of the CO2 gas.

[0014] Preferably, the cryogenic cooling medium is a cryogenic coolant, which is a coolant or cooling oil with a temperature below -85°C to -110°C.

[0015] Preferably, the ultra-low temperature CO2 separation tower is made of a low-temperature resistant material, which is one of a metal material, plastic, or resin that can withstand temperatures down to -120℃. The ultra-low temperature CO2 separation tower has a packing layer inside, which is divided into a gas treatment packing layer and a gas dehydration packing layer. The packing layer has a certain height, and each packing layer contains several mesh liquid film spheres. The mesh liquid film spheres are spherical structures with an inner hollow outer mesh. A liquid spraying device is provided above the gas treatment packing layer. A packing layer maintenance port is provided on the outer shell of the packing layer.

[0016] A carbon dioxide mixed gas cryogenic separation and recovery system under normal pressure is based on the technical idea of ​​using a special temperature zone heat pump with a large temperature difference to rapidly cool the flue gas or mixed gas containing carbon dioxide to below -78°C. The carbon dioxide gas immediately turns into solid carbon dioxide (dry ice) and is separated from other gases. The solid carbon dioxide is separated out and the other gases are discharged, thus obtaining pure carbon dioxide. The carbon dioxide is stored in a special container and then gasified for use when needed.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: Carbon dioxide exists in a gaseous state at normal temperature and pressure, and turns into a solid at -78°C, commonly known as dry ice, which is solid carbon dioxide. This utility model uses a heat pump with a large temperature difference and a special temperature zone to rapidly cool flue gas or mixed gas containing carbon dioxide to below -78°C. The carbon dioxide gas immediately turns into solid carbon dioxide (dry ice) and is separated from other gases. By separating the solid carbon dioxide and discharging the other gases, pure carbon dioxide is obtained. The carbon dioxide is stored in a special container and then vaporized for use when needed. On the one hand, this method makes it very easy to separate, recover, and store carbon dioxide gas, and is particularly suitable for the treatment and carbon recovery of combustion flue gas or flue gas from smelting, ceramics, glass and other industries, so as to achieve zero carbon emissions in energy production and smelting production; and the recovered carbon dioxide can be used to manufacture gasoline, diesel, methanol, combustible gas, chemical raw materials, etc., and can also be used for pollution control and special effects in entertainment venues. On the other hand, a heat pump with a large temperature difference and a special temperature zone is used to obtain an ultra-low temperature cold source. This heat pump has a fast cooling speed, a large temperature difference, and high energy efficiency. It can generate a temperature difference of more than 200°C in one step under normal pressure. Therefore, it can achieve rapid cooling of carbon dioxide gas under normal pressure, complete the phase change of carbon dioxide, produce dry ice, and separate other gases. On the other hand, the heat generated during the manufacturing of ultra-low temperature and the latent heat of carbon dioxide phase change can be completely recovered and used for heating, hot water and other heat needs. The system for recovering carbon dioxide gas of this invention is simple, requires few devices, and achieves thorough and clean recovery, yielding pure carbon dioxide. The method of this invention can directly separate and recover carbon dioxide gas from exhaust gas in one step under normal pressure, achieving zero carbon emissions. Furthermore, the recovered carbon dioxide can be converted and utilized, greatly reducing the consumption of primary energy. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a recycling system according to the present invention; The following labels are used in the attached diagram: 1. Non-CO2 gas outlet; 2. Cryogenic CO2 separation tower; 3. CO2 mixed gas inlet; 4. Solid CO2 collection bin; 5. Solid CO2 outlet; 6. Cryogenic cold source medium inlet of the separation tower; 7. Cryogenic cold source medium outlet of the separation tower; 8. High-temperature hot water inlet; 9. High-temperature hot water outlet; 10. Heat pump with large temperature difference in special temperature zone; 11. Heat pump power unit; 12. Heat pump cryogenic cold source outlet; 13. Heat pump cryogenic cold source inlet; 14. Cryogenic cold source delivery pipe; 141-Cryogenic liquid supply pipe; 142-Cryogenic liquid return pipe. Detailed Implementation

[0019] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. This utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this utility model more thorough and complete.

[0020] like Figure 1 As shown, this utility model discloses a carbon dioxide mixed gas cryogenic separation and recovery system under normal pressure, comprising an ultra-low temperature CO2 separation tower 2 and a large temperature difference special temperature zone heat pump 10. The ultra-low temperature CO2 separation tower 2 and the large temperature difference special temperature zone heat pump 10 are connected by an ultra-low temperature cold source delivery pipe 14. The ultra-low temperature CO2 separation tower 2 has a non-CO2 gas outlet 1 at its top and a solid CO2 collection chamber 4 at its bottom. A solid CO2 outlet 5 is located below the solid CO2 collection chamber 4. The ultra-low temperature CO2 separation tower 2 has a CO2 mixed gas inlet 3 on one side and an ultra-low temperature cold source medium inlet 6 and an ultra-low temperature cold source medium outlet 6 on the other side. The large temperature difference special temperature zone heat pump 10 has a high-temperature hot water inlet 8 and a high-temperature hot water outlet 9 above it, a heat pump power unit 11 on its side, and a heat pump ultra-low temperature cold source outlet 12 and a heat pump ultra-low temperature cold source inlet 13 below it; the ultra-low temperature cold source delivery pipe 14 includes an ultra-low temperature liquid supply pipe 141 and an ultra-low temperature liquid return pipe 142. One end of the ultra-low temperature liquid supply pipe 141 is connected to the ultra-low temperature cold source medium inlet 6 of the separation tower, and the other end is connected to the heat pump ultra-low temperature cold source outlet 12; one end of the ultra-low temperature liquid return pipe 142 is connected to the ultra-low temperature cold source medium outlet 7 of the separation tower, and the other end is connected to the heat pump ultra-low temperature cold source inlet 13.

[0021] In some implementations, the large temperature difference special temperature zone heat pump can quickly generate a temperature difference of over 200°C, enabling a one-step process to directly reduce the temperature to below -80°C under normal pressure while simultaneously obtaining a high temperature of over 100°C, facilitating heat recovery and utilization.

[0022] In some implementations, the large temperature difference special temperature zone heat pump adopts a Stirling heat pump unit or a reverse Brayton cycle heat pump unit. The Stirling heat pump unit cools the ultra-low temperature medium to below -85°C. After passing through a special equipment, such as a cryogenic liquid film sphere gas treatment device or other cryogenic gas treatment equipment, the ultra-low temperature medium is brought into full contact with the flue gas. When the flue gas temperature drops to below -78°C, the carbon dioxide in the flue gas becomes solid carbon dioxide and is separated. The solid is collected and recovered to obtain carbon dioxide, while other gases are discharged. The discharged non-carbon dioxide gases are cryogenic gases that can be used for cooling. When using solid carbon dioxide, it is first vaporized. The vaporization process can generate electricity, and the cooling process can be used to produce gasoline, diesel, methanol, and other products.

[0023] In some implementations, the ultra-low temperature CO2 separation tower is a uniform ultra-low temperature environment to ensure that the CO2 gas is completely and thoroughly cooled to below -80°C, and that no CO2 gas escapes, thus ensuring complete separation of the CO2 gas.

[0024] In some embodiments, the coolant is a cryogenic coolant, which is a coolant or cooling oil with a temperature below -85°C to -110°C.

[0025] In some embodiments, the ultra-low temperature CO2 separation tower is made of a low-temperature resistant material, which is one of a metal, plastic, or resin that can withstand temperatures down to -120°C. The ultra-low temperature CO2 separation tower has an internal packing layer, which is divided into a gas treatment packing layer and a gas dehydration packing layer. The packing layer has a certain height, and each packing layer contains several mesh-like liquid film spheres. The mesh-like liquid film spheres have a hollow inner and mesh outer spherical structure. A liquid spraying device is provided above the gas treatment packing layer. A packing layer maintenance port is provided on the outer shell of the packing layer.

[0026] In this embodiment, a method for cryogenic separation and recovery of carbon dioxide mixed gas under normal pressure according to the present invention includes the following steps: S1: Turn on the large temperature difference special temperature zone heat pump 10. Driven by the heat pump power unit 11, the hot end of the large temperature difference special temperature zone heat pump 10 generates heat to heat the high temperature hot water. The hot water enters the heat pump from the high temperature hot water inlet 8, and after being heated by the hot end of the large temperature difference special temperature zone heat pump 10, it flows out from the high temperature hot water outlet 9. S2: The cold end of the large temperature difference special temperature zone heat pump 10 cools down rapidly, generating a cold source below -80℃. Through the continuous circulation of the ultra-low temperature cooling medium, the ultra-low temperature cold energy is transported to the ultra-low temperature CO2 separation tower 2 through the ultra-low temperature cold source delivery pipe 14. S3: When the temperature inside the ultra-low temperature CO2 separation tower 2 is below -80℃, a CO2-containing mixed gas is sent into the ultra-low temperature CO2 separation tower 2 from the CO2 mixed gas inlet 3. The CO2 mixed gas immediately cools down to below -80℃. At this time, the CO2 gas quickly and directly turns into solid crystals, the CO2 volume is reduced by about 700 times, and the latent heat of phase change is released. The latent heat is recovered and utilized by the heat pump. S4: As the solid crystals grow, they fall under the influence of gravity into the solid CO2 collection chamber 4 at the bottom of the ultra-low temperature CO2 separation tower 2 when they reach a certain size. Other non-CO2 gases are discharged from the non-CO2 gas outlet 1 at the top of the ultra-low temperature CO2 separation tower 2. Thus, CO2 gas is separated from the CO2 mixture under ultra-low temperature conditions, and the CO2 gas becomes solid and is discharged from the solid CO2 outlet 5 at the bottom of the ultra-low temperature CO2 separation tower 2, completing the separation and collection of CO2.

[0027] This invention relates to zero-carbon treatment of emissions containing a mixture of gaseous carbon dioxide, specifically by completely separating and recovering the carbon dioxide from the emitted gas. The main component of carbon emissions is carbon dioxide, a waste gas emitted during industrial production, such as energy production, steelmaking, smelting, ceramics, and glass manufacturing processes requiring high temperatures. These emissions typically contain 5% to 15% carbon dioxide, and due to the massive volume of these emissions, the amount of carbon dioxide released into the atmosphere is also substantial. This invention can completely separate and recover carbon dioxide from the emitted waste gas, achieving zero-carbon emissions. Furthermore, the recovered carbon dioxide can be converted and utilized, significantly reducing primary energy consumption.

[0028] The system for recovering carbon dioxide gas according to this invention is simple, requires few devices, and achieves thorough and clean recovery. The obtained carbon dioxide is pure and easy to reuse, and the heat and cold energy generated during the recovery process can be recovered and reused.

[0029] The recovery and utilization of pure solid carbon dioxide is of great significance and has high comprehensive utilization value. The reuse process can also be carried out by combined cooling and power generation, generating electricity while simultaneously providing cooling, resulting in high comprehensive energy utilization efficiency. The carbon dioxide gas after power generation can be hydrogenated to produce methanol, combustible gas, gasoline, diesel, and other chemical products. Currently, the technology for synthesizing carbon dioxide products is mature. Combining this utility model's pure carbon dioxide recovery technology with the formation of a new upstream and downstream industrial chain will bring excellent comprehensive economic benefits.

[0030] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A system for the cryogenic separation and recovery of carbon dioxide mixed gas under normal pressure, characterized in that: It includes an ultra-low temperature CO2 separation tower (2) and a large temperature difference special temperature zone heat pump (10), and the ultra-low temperature CO2 separation tower (2) and the large temperature difference special temperature zone heat pump (10) are connected through an ultra-low temperature cold source delivery pipe (14).

2. The separation and recovery system as described in claim 1, characterized in that: The ultra-low temperature CO2 separation tower (2) is provided with a non-CO2 gas outlet (1) above it and a solid CO2 collection chamber (4) below it. A solid CO2 outlet (5) is provided below the solid CO2 collection chamber (4). A CO2 mixed gas inlet (3) is provided on one side of the ultra-low temperature CO2 separation tower (2), and an ultra-low temperature cold source medium inlet (6) and an ultra-low temperature cold source medium outlet (7) are provided on the other side.

3. The separation and recovery system as described in claim 1 or 2, characterized in that: The large temperature difference special temperature zone heat pump (10) is provided with a high temperature hot water inlet (8) and a high temperature hot water outlet (9) on its upper side, a heat pump power unit (11) on its side, and a heat pump ultra-low temperature cold source outlet (12) and a heat pump ultra-low temperature cold source inlet (13) below it.

4. The separation and recovery system as described in claim 1, characterized in that: The cryogenic cold source delivery pipe (14) includes a cryogenic liquid supply pipe (141) and a cryogenic liquid return pipe (142). One end of the cryogenic liquid supply pipe (141) is connected to the cryogenic cold source medium inlet (6) of the separation tower, and the other end is connected to the cryogenic cold source outlet (12) of the heat pump. One end of the cryogenic liquid return pipe (142) is connected to the cryogenic cold source medium outlet (7) of the separation tower, and the other end is connected to the cryogenic cold source inlet (13) of the heat pump.

5. The separation and recovery system as described in claim 1, characterized in that: The large temperature difference special temperature zone heat pump (10) can quickly generate a temperature difference of more than 200°C, and can achieve a one-step method to directly reduce the temperature to below -80°C under normal pressure, while obtaining a high temperature of more than 100°C, which is convenient for heat recovery and utilization.

6. The separation and recovery system as described in claim 5, characterized in that: The large temperature difference special temperature zone heat pump (10) adopts a Stirling heat pump unit or a reverse Brayton cycle heat pump unit.

7. The separation and recovery system as described in claim 1 or 2, characterized in that: The ultra-low temperature CO2 separation tower (2) has a uniform ultra-low temperature environment to ensure that the CO2 gas is completely and thoroughly cooled to below -80℃, and that no CO2 gas escapes, thus ensuring complete separation of the CO2 gas.

8. The separation and recovery system as described in claim 1 or 2, characterized in that: The ultra-low temperature CO2 separation tower (2) is made of a low temperature resistant material, which is one of the following: metal, plastic, or resin that can withstand temperatures down to -120℃. The ultra-low temperature CO2 separation tower (2) is equipped with a packing layer inside. The packing layer is divided into a gas treatment packing layer and a gas dehydration packing layer. The packing layer has a certain height. Each packing layer contains several mesh liquid film spheres. The mesh liquid film spheres are spherical structures with an inner hollow outer mesh. A liquid spraying device is provided above the gas treatment packing layer. A packing layer maintenance port is provided on the outer shell of the packing layer.

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