Desublimation separation tower based on heat exchange tube with triple-spiral structure and implementation method of desublimation separation tower

Abstract

The invention discloses a desublimation separation tower based on a heat exchange tube with a three-spiral structure and an implementation method of the desublimation separation tower. The three-spiral-structure heat exchange pipes are adopted, H2, an initial mixed gas pipe and cold flow respectively flow in one heat exchange pipe, and the three heat exchange pipes are tightly attached in a spiral mode; the heat exchange tube with the triple-spiral structure can realize heat exchange between tube passes and shell passes, and also can perform heat exchange between the tube passes, so that stepped recycling of cold energy and heat energy is realized; the heat exchange tube of the three-spiral structure has the advantages of being close in attachment, large in heat exchange area and high in heat exchange efficiency, heat exchange between tube passes and shell passes and between tube passes can be achieved at the same time, the spiral structure disturbs tube pass materials, the heat exchange coefficient is increased, and the heat exchange efficiency is improved. The system can be widely applied to comprehensive energy systems, separation systems and cold and heat recycling systems.

Description

Technical Field

[0001] The invention relates to the field of heat exchangers, and in particular to a condensation and sublimation separation tower based on a triple-helix structure heat exchange tube and a realization method thereof. Background Art

[0002] Under the background of dual carbon, the research on low-carbon green integrated energy system is becoming increasingly important. The integrated energy system involves the conversion of multiple energy sources and the exchange of multiple energies, among which the exchange of cold and heat is particularly important. Therefore, efficient multi-stream heat exchangers play an important role in energy conversion and cascade recycling. For example, in the integrated cooling and heating system with CO2 as the working fluid, multiple streams such as liquid CO2, gaseous CO2 and refrigerant are involved. In this scenario, the multi-stream heat exchanger has the advantages of large heat exchange area, high heat exchange efficiency and high integration. On the other hand, it can be applied to the separation of multi-impurity mixed gas, through heat exchange of streams at different temperatures, to separate materials with different boiling points and condensation temperatures, and to realize the recycling of cold energy and heat energy, such as the separation of supercritical CO2-H2 mixed gas.

[0003] In the desublimation separation process of supercritical CO2 and H2 mixed gas, the tube side of the desublimation separation tower requires three streams: initial mixed gas, H2 and external cold source. In the desublimation stage, the cold energy of H2 and cold source needs to be transferred to the low-proportion mixed gas in the shell side to make CO2 desublimate. In the melting stage, the heat energy carried by the initial mixed gas needs to be transferred to the solid CO2 attached to the surface of the heat exchange tube. At present, the research on low-temperature desublimation separation methods of CO2 and H2 includes snow-melting separation by direct cooling of liquid nitrogen, expansion valve throttling and refrigerant refrigeration. Snow-melting separation still needs to continue to separate N2 and CO2. Expansion valve throttling often requires liquefaction and then expansion to form solid CO2. Refrigerants have problems such as high energy consumption and greenhouse effect of traditional refrigerants. The current heat exchange tubes are mainly based on heat exchange between two materials. If heat exchange switching of three or more materials is involved, multiple heat exchangers need to be realized in series, and the system integration is poor. Summary of the invention

[0004] Aiming at the problem of multi-stream heat exchange in a continuous separation system for low-temperature condensation, sublimation and melting switching of a supercritical CO2 and H2 mixed gas, the present invention proposes a condensation and sublimation separation tower based on a triple-helix structured heat exchange tube; in the condensation and sublimation separation process of a supercritical CO2 and H2 mixed gas, the tube side of the condensation and sublimation separation tower requires three streams, namely, the mixed gas, H2 and an external cold source; in the condensation stage, the cold energy of H2 and the cold source needs to be transferred to the shell side mixed gas to cause CO2 to condense; in the melting stage, the heat energy carried by the mixed gas needs to be transferred to the solid CO2 attached to the surface of the heat exchange tube; therefore, the heat exchange tubes of the three streams in the tube side also need to transfer cold and hot energy; the present invention adopts a triple-helix structured heat exchange tube, which can realize heat exchange between the tube side and the shell side, as well as heat exchange between the tube sides, thereby realizing the step-by-step recovery and utilization of cold and heat energy.

[0005] One object of the present invention is to provide a desublimation separation tower based on a triple helical structure heat exchange tube.

[0006] The desublimation separation tower based on the triple-helix structure heat exchange tube of the present invention comprises: a desublimation separation tower shell, a cooling inlet, an H2 inlet, an initial mixed gas inlet, a low-ratio mixed gas inlet, a cooling outlet, a side wall H2 outlet, an initial mixed gas outlet, a top H2 outlet, a liquid CO2 outlet, a triple-helix structure heat exchange tube, a first to a fourth valve, a cooling unit and a control system; wherein the desublimation separation tower shell is a closed shell with a space inside; a cooling inlet, an H2 inlet, an initial mixed gas inlet and a low-ratio mixed gas inlet are arranged on one side wall of the desublimation separation tower shell, a cooling outlet, a side wall H2 outlet and an initial mixed gas outlet are arranged on the other side wall of the desublimation separation tower shell, a top H2 outlet is arranged at the top of the desublimation separation tower shell, and a liquid CO2 outlet is arranged at the bottom of the desublimation separation tower shell; a triple-helix structure heat exchange tube is arranged in the desublimation separation tower;

[0007] The triple-helix structure heat exchange tube includes: an H2 tube, an initial mixed gas tube and a cold flow tube, wherein the H2 tube, the initial mixed gas tube and the cold flow tube are tightly fitted in a spiral form; the inlet of the H2 tube is connected to the H2 inlet of the condensation and sublimation separation tower, the outlet of the H2 tube is connected to the side wall H2 outlet of the condensation and sublimation separation tower, the inlet of the initial mixed gas tube is connected to the initial mixed gas inlet of the condensation and sublimation separation tower, the outlet of the initial mixed gas tube is connected to the initial mixed gas outlet of the condensation and sublimation separation tower, the inlet of the cold flow tube is connected to the cooling inlet of the condensation and sublimation separation tower, and the outlet of the cold flow tube is connected to the cooling outlet of the condensation and sublimation separation tower;

[0008] The low-ratio mixed gas is connected to the inlet of the first valve through a pipeline, and the outlet of the first valve is connected to the low-ratio mixed gas inlet of the condensation and sublimation separation tower; the initial mixed gas is connected to the inlet of the second valve through a pipeline, and the outlet of the second valve is connected to the initial mixed gas inlet of the condensation and sublimation separation tower; the outlet of the refrigeration unit is connected to the inlet of the third valve, and the outlet of the third valve is connected to the refrigeration inlet of the condensation and sublimation separation tower; the top H2 outlet of the condensation and sublimation separation tower is connected to the H2 inlet of the condensation and sublimation separation tower; the side wall return cooling fluid outlet of the condensation and sublimation separation tower is connected to the inlet of the fourth valve, and the outlet of the fourth valve is connected to the inlet of the refrigeration unit through a pipeline;

[0009] The first to fourth valves and the cooling units are respectively connected to the control system;

[0010] The low-ratio mixed gas after liquefaction separation enters the desublimation separation tower for further separation, and the desublimation separation tower performs melting or desublimation;

[0011] When the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation is switched to melting; the first to fourth valves are controlled by the control system to switch the melting or desublimation of the desublimation separation tower to achieve continuous desublimation separation;

[0012] When the desublimation separation tower is condensing, the low-proportion mixed gas outside the triple-helix structure heat exchange tube exchanges heat with the cooling fluid from the refrigeration unit in the cold flow tube of the triple-helix structure heat exchange tube in the desublimation separation tower. The triple-helix structure heat exchange tube enables the low-temperature H2 and the cooling fluid to effectively transfer heat to the low-proportion mixed gas to achieve the desublimation of CO2, and the solid CO2 adheres to the surface of the triple-helix structure heat exchange tube; when the desublimation separation tower is melting, a large amount of solid CO2 adheres to the surface of the triple-helix structure heat exchange tube after the desublimation process in the previous stage, and exchanges heat with the initial mixed gas carrying heat energy in the initial mixed gas tube of the triple-helix structure heat exchange tube; the H2 tube, the initial mixed gas tube and the cold flow tube exchange heat with the low-proportion mixed gas in the shell during the desublimation and melting process. Exchange, the triple helix structure increases the flow distance of the fluid in the condensation and sublimation separation tower, and the heat exchange area of ​​the heat exchange tube is also increased, thereby improving the heat exchange efficiency; the fluid flows in the heat exchange tube in a spiral shape, and this flow mode not only enhances the mixing and disturbance of the fluid, but also the fluid in the triple helix structure heat exchange tube produces a pair of reverse vortex secondary flows due to the centrifugal force, Coriolis force and buoyancy; the existence of this secondary flow significantly improves the heat transfer coefficient of the tube side film, thereby further increasing the heat transfer coefficient, and significantly improving the heat transfer efficiency of the entire triple helix structure heat exchange tube. In the condensation and sublimation separation of a low-proportion mixed gas, the heat energy of the initial mixed gas and the cold energy of H2 are recycled in the melting and condensation processes, respectively, reducing the separation energy consumption.

[0013] When the sublimation separation tower is condensing, the first valve is opened, the second valve is closed, the third valve is opened, and the fourth valve is opened at the same time; the low-proportion mixed gas enters the sublimation separation tower from the low-proportion mixed gas inlet through the first valve and is located outside the triple-helix structure heat exchange tube; at the same time, the cooling fluid from the cooling unit enters the cold flow tube of the triple-helix structure heat exchange tube located in the sublimation separation tower from the cooling inlet through the third valve; the low-proportion mixed gas located outside the triple-helix structure heat exchange tube in the sublimation separation tower and the low-proportion mixed gas from the cooling unit located in the triple-helix structure heat exchange tube in the sublimation separation tower. The cooling fluid in the cold flow tube of the heat pipe undergoes heat exchange, and the liquid CO2 in the low-proportion mixed gas condenses and adheres to the outer wall of the triple-helix structure heat exchange tube, while the separated gaseous H2 flows out from the H2 outlet at the top of the condensation and sublimation separation tower, and enters the H2 tube of the triple-helix structure heat exchange tube located in the condensation and sublimation separation tower from the H2 inlet of the condensation and sublimation separation tower. After the cold energy carried is recycled, the high-purity H2 flows out of the condensation and sublimation separation tower from the H2 outlet on the side wall through the H2 tube of the triple-helix structure heat exchange tube and is output from the condensation and sublimation separation system to obtain a separated high-purity H2 product.

[0014] When the sublimation separation tower is melting, the first valve is closed, the second valve is opened, the third valve is closed, and the fourth valve is closed at the same time; the initial mixed gas carrying heat energy enters the initial mixed gas pipe of the three-helix structure heat exchange tube located in the sublimation separation tower through the second valve from the initial mixed gas inlet of the sublimation separation tower; after the sublimation separation tower has undergone the previous stage of the sublimation process, a large amount of solid CO2 is attached to the surface of the three-helix structure heat exchange tube in the sublimation separation tower, and the initial mixed gas carrying heat energy in the initial mixed gas pipe of the three-helix structure heat exchange tube exchanges heat with the solid CO2, and the solid CO2 melts into liquid CO2, and the liquid CO2 flows out from the liquid CO2 outlet at the bottom of the sublimation separation tower to obtain the separated liquid CO2 product.

[0015] Furthermore, the present invention adopts a first desublimation separation tower and a second desublimation separation tower, and the first to fourth valves adopt first to fourth three-way valves to form a continuous desublimation separation system; the first to fourth three-way valves and the refrigeration unit are respectively connected to the control system; the low-proportion mixed gas is connected to the first port of the first three-way valve through a pipeline, the second port of the first three-way valve is connected to the low-proportion mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-proportion mixed gas inlet of the second desublimation separation tower; the initial mixed gas is connected to the first port of the second three-way valve through a pipeline, the second port of the second three-way valve is connected to the initial mixed gas inlet of the first desublimation separation tower, and the third port of the second three-way valve is connected to the initial mixed gas inlet of the second desublimation separation tower; the outlet of the refrigeration unit is connected to the first port of the third three-way valve, the second port of the third three-way valve is connected to the refrigeration inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the refrigeration inlet of the third three-way valve. The inlet is connected to the cooling inlet of the second desublimation separation tower; the top H2 outlet of the first desublimation separation tower is connected to the H2 inlet of the first desublimation separation tower, and the top H2 outlet of the second desublimation separation tower is connected to the H2 inlet of the second desublimation separation tower; the side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, and the side wall cooling fluid outlet of the second desublimation separation tower is connected to the third port of the fourth three-way valve, and the first port of the fourth three-way valve is connected to the inlet of the cooling unit through a pipeline; the side wall H2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total H2 outlet and output through a pipeline, the initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total initial mixed gas outlet, and transported to the liquefaction separation system through a pipeline; the liquid CO2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total liquid CO2 outlet and output through a pipeline.

[0016] Furthermore, it also includes an inlet filter and an outlet filter. The inlet filter is arranged in front of the first port of the second three-way valve; and the outlet filter is arranged at the total H2 outlet of the first desublimation separation tower and the second desublimation separation tower.

[0017] It also includes pressure gauges, which are respectively arranged at the top H2 outlets of the first desublimation separation tower and the second desublimation separation tower to monitor the pressure in the desublimation separation tower in real time. There is no pressurization or depressurization during the process, so the pressure remains unchanged; pressure gauges are respectively arranged at the second port and the third port of the second three-way valve to monitor the pressure of the initial mixed gas in real time, and the pressure gauges are connected to the control system.

[0018] It also includes a temperature sensor, which is arranged on the pipes of the top H2 outlets of the first and second desublimation separation towers, and the temperature sensor is connected to the control system to monitor the temperature at the top H2 outlet of the desublimation separation tower in real time; when the desublimation separation tower is desublimating, when the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation must be switched to melting and switched to another desublimation separation tower to continue desublimation.

[0019] It also includes a liquid collecting tank, which is arranged at the total liquid CO2 outlet of the first desublimation separation tower and the second desublimation separation tower to play a buffering role.

[0020] It also includes safety valves, which are respectively arranged at the top H2 outlets of the first desublimation separation tower and the second desublimation separation tower, and the safety valves are connected to the control system.

[0021] Another object of the present invention is to provide a method for realizing a condensation and sublimation separation tower based on a triple-helix structure heat exchange tube.

[0022] The method for realizing a desublimation separation tower based on a triple helical structure heat exchange tube of the present invention comprises the following steps:

[0023] 1) Set up a desublimation separation tower:

[0024] The H2 tube, the initial mixed gas tube and the cold flow tube are tightly fitted in a spiral form; the inlet of the H2 tube is connected to the H2 inlet of the condensation and sublimation separation tower, the outlet of the H2 tube is connected to the H2 outlet of the side wall of the condensation and sublimation separation tower, the inlet of the initial mixed gas tube is connected to the initial mixed gas inlet of the condensation and sublimation separation tower, the outlet of the initial mixed gas tube is connected to the initial mixed gas outlet of the condensation and sublimation separation tower, the inlet of the cold flow tube is connected to the cooling inlet of the condensation and sublimation separation tower, and the outlet of the cold flow tube is connected to the cooling outlet of the condensation and sublimation separation tower;

[0025] The low-proportion mixed gas is connected to the inlet of the first valve through a pipeline, and the outlet of the first valve is connected to the low-proportion mixed gas inlet of the condensation and sublimation separation tower; the initial mixed gas is connected to the inlet of the second valve through a pipeline, and the outlet of the second valve is connected to the initial mixed gas inlet of the condensation and sublimation separation tower; the outlet of the refrigeration unit is connected to the inlet of the third valve, and the outlet of the third valve is connected to the refrigeration inlet of the condensation and sublimation separation tower; the top H2 outlet of the condensation and sublimation separation tower is connected to the H2 inlet of the condensation and sublimation separation tower; the side wall return cooling fluid outlet of the condensation and sublimation separation tower is connected to the inlet of the fourth valve, and the outlet of the fourth valve is connected to the inlet of the refrigeration unit through a pipeline; the side wall H2 outlet of the condensation and sublimation separation tower is output through a pipeline; the initial mixed gas outlet of the condensation and sublimation separation tower is transported to the liquefaction separation system through a pipeline; the liquid CO2 outlet of the condensation and sublimation separation tower is output through a pipeline;

[0026] The first to fourth valves and the cooling units are respectively connected to the control system;

[0027] 2) The low-proportion mixed gas after liquefaction separation enters the desublimation separation tower for further separation, and the desublimation separation tower performs melting or desublimation:

[0028] During desublimation in the desublimation separation tower, the low-proportion mixed gas outside the triple-helix structure heat exchange tube exchanges heat with the cooling fluid from the cooling unit located in the cold flow tube of the triple-helix structure heat exchange tube in the desublimation separation tower. The triple-helix structure heat exchange tube enables the low-temperature H2 and the cooling fluid to effectively transfer heat to the low-proportion mixed gas, thereby achieving desublimation of CO2, and solid CO2 adheres to the surface of the triple-helix structure heat exchange tube.

[0029] When the desublimation separation tower is melting, a large amount of solid CO2 adheres to the surface of the triple helix structure heat exchange tube after the desublimation process in the previous stage, and performs heat exchange with the initial mixed gas carrying heat energy in the initial mixed gas tube of the triple helix structure heat exchange tube;

[0030] The H2 tube, the initial mixed gas tube and the cold flow tube exchange heat with the low-proportion mixed gas in the shell during the condensation and melting process. The triple helix structure increases the flow distance of the fluid in the condensation and sublimation separation tower, and the heat exchange area of ​​the heat exchange tube is increased, thereby improving the heat exchange efficiency; the fluid flows in a spiral shape in the heat exchange tube. This flow mode not only enhances the mixing and disturbance of the fluid, but also the fluid in the triple helix heat exchange tube generates a pair of reverse vortex secondary flows due to the centrifugal force, Coriolis force and buoyancy; the existence of this secondary flow significantly improves the heat transfer coefficient of the tube side film, thereby further increasing the heat transfer coefficient, and significantly improving the heat transfer efficiency of the entire triple helix heat exchange tube. In the condensation and sublimation separation of the low-proportion mixed gas, the heat energy of the initial mixed gas and the cold energy of H2 are recycled in the melting and condensation processes, respectively, reducing the separation energy consumption;

[0031] 3) When the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation is switched to melting; the first to fourth valves are controlled by the control system to switch the melting or desublimation of the desublimation separation tower to achieve continuous desublimation separation.

[0032] The first desublimation separation tower and the second desublimation separation tower are used, and the first to fourth valves are the first to fourth three-way valves, forming a continuous desublimation separation system; when the first desublimation separation tower is desublimating, the second desublimation separation tower is melting at the same time, and when the first desublimation separation tower is melting, the second desublimation separation tower is desublimating at the same time; the first to fourth three-way valves are controlled by the control system to switch the first desublimation separation tower and the second desublimation separation tower, so as to realize continuous desublimation separation:

[0033] The first desublimation separation tower desublimates while the second desublimation separation tower melts: the first port and the second port of the first three-way valve are opened while the third port is closed, the first port and the third port of the second three-way valve are opened while the second port is closed, the first port and the second port of the third three-way valve are opened while the third port is closed, and the first port and the second port of the fourth three-way valve are opened while the third port is closed; the low-proportion mixed gas enters the first desublimation separation tower from the first port through the second port of the first three-way valve from the low-proportion mixed gas inlet of the first desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the third three-way valve from the cooling inlet of the first desublimation separation tower, and the first desublimation separation tower desublimates; at the same time, the initial mixed gas carrying heat energy enters the heat exchange tube of the second desublimation separation tower from the first port through the third port of the second three-way valve from the initial mixed gas inlet of the second desublimation separation tower, and the second desublimation separation tower melts;

[0034] The first desublimation separation tower melts while the second desublimation separation tower desublimates: open the first port and the third port of the first three-way valve while closing the second port, open the first port and the second port of the second three-way valve while closing the third port, open the first port and the third port of the third three-way valve while closing the second port, open the first port and the third port of the fourth three-way valve while closing the second port; the initial mixed gas carrying heat energy enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the second three-way valve from the initial mixed gas inlet of the first desublimation separation tower, and the first desublimation separation tower is melted; at the same time, the low-proportion mixed gas enters the second desublimation separation tower from the first port through the third port of the first three-way valve from the low-proportion mixed gas inlet of the second desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the second desublimation separation tower from the first port through the third port of the third three-way valve from the cooling inlet of the second desublimation separation tower, and the second desublimation separation tower is desublimated;

[0035] By switching the material flow directions of the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve, the desublimation and melting processes of the first desublimation separation tower and the second desublimation separation tower are switched; in the whole process, the cold energy and heat energy carried by the material are utilized in stages in the heat exchangers at each stage, thereby minimizing the separation energy consumption.

[0036] In step 2), when the desublimation separation tower desublimates, the first valve is opened, the second valve is closed, the third valve is opened, and the fourth valve is opened at the same time; the low-ratio mixed gas enters the desublimation separation tower from the low-ratio mixed gas inlet through the first valve, and is located outside the triple-helix structure heat exchange tube; at the same time, the cooling fluid from the cooling unit enters the cold flow tube located in the triple-helix structure heat exchange tube in the desublimation separation tower from the cooling inlet through the third valve; the low-ratio mixed gas located outside the triple-helix structure heat exchange tube in the desublimation separation tower and the cooling fluid from the cooling unit located in the triple-helix structure heat exchange tube The cooling fluid in the cold flow tube of the spiral structure heat exchange tube undergoes heat exchange, and the liquid CO2 in the low-proportion mixed gas condenses and adheres to the outer wall of the triple-helix structure heat exchange tube, while the separated gaseous H2 flows out from the H2 outlet at the top of the desublimation separation tower, enters the H2 tube of the triple-helix structure heat exchange tube located in the desublimation separation tower from the H2 inlet of the desublimation separation tower, and after the cold energy carried is recycled, the high-purity H2 flows out of the desublimation separation tower from the H2 outlet on the side wall through the H2 tube of the triple-helix structure heat exchange tube and is output from the desublimation separation system to obtain a separated high-purity H2 product.

[0037] When the sublimation separation tower is melting, the first valve is closed, the second valve is opened, the third valve is closed, and the fourth valve is closed at the same time; the initial mixed gas carrying heat energy enters the initial mixed gas pipe of the three-helix structure heat exchange tube located in the sublimation separation tower through the second valve from the initial mixed gas inlet of the sublimation separation tower; after the sublimation separation tower has undergone the previous stage of the sublimation process, a large amount of solid CO2 is attached to the surface of the three-helix structure heat exchange tube in the sublimation separation tower, and the initial mixed gas carrying heat energy in the initial mixed gas pipe of the three-helix structure heat exchange tube exchanges heat with the solid CO2, and the solid CO2 melts into liquid CO2, and the liquid CO2 flows out from the liquid CO2 outlet at the bottom of the sublimation separation tower to obtain the separated liquid CO2 product.

[0038] In step 3), a temperature sensor is provided on the pipe of the top H2 outlet of the desublimation separation tower, and the temperature sensor is connected to the control system to monitor the temperature at the top H2 outlet of the desublimation separation tower in real time; when the desublimation separation tower desublimates, when the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed and the desublimation must be switched to melting.

[0039] The condensation temperature is related to the concentration of CO2 in the low-proportion mixed gas. The higher the concentration of CO2 in the low-proportion mixed gas, the higher the condensation temperature. The lower the concentration of CO2 in the low-proportion gas, the lower the condensation temperature.

[0040] Advantages of the present invention:

[0041] The present invention adopts a triple-helix structure heat exchange tube, which can realize heat exchange between the tube side and the shell side, and heat exchange between the tube sides, thereby realizing the cascade recovery and utilization of cold energy and heat energy; the triple-helix structure heat exchange tube has the characteristics of close fitting, large heat exchange area and high heat exchange efficiency, and can simultaneously realize heat exchange between the tube side and the shell side, and between the tube sides. The spiral structure forms a disturbance on the tube side material, and the heat transfer coefficient is improved. It can be widely used in integrated energy systems, separation systems and cold and heat recovery systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of an embodiment of a desublimation separation tower based on a triple-helix structure heat exchange tube of the present invention;

[0043] Figure 2 A schematic diagram of a triple-helix structure heat exchange tube of an embodiment of a desublimation separation tower based on a triple-helix structure heat exchange tube of the present invention;

[0044] Figure 3 It is a schematic diagram of a continuous desublimation separation system composed of two towers based on a desublimation separation tower with a triple-helix structure heat exchange tube according to the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0046] Embodiment 1

[0047] like Figure 1 As shown, the desublimation separation tower based on the triple-helix structure heat exchange tube of this embodiment includes: a desublimation separation tower shell, a cooling inlet, an H2 inlet, an initial mixed gas inlet, a low-proportion mixed gas inlet, a cooling outlet, a side wall H2 outlet, an initial mixed gas outlet, a top H2 outlet, a liquid CO2 outlet, a triple-helix structure heat exchange tube, the first to fourth valves, a cooling unit, an inlet filter, an outlet filter, a pressure gauge, a temperature sensor, a liquid collecting tank, a safety valve and a control system; wherein, the desublimation separation tower shell is a closed shell with a space inside; a cooling inlet, an H2 inlet, an initial mixed gas inlet and a low-proportion mixed gas inlet are arranged on one side wall of the desublimation separation tower shell, a cooling outlet, a side wall H2 outlet and an initial mixed gas outlet are arranged on the other side wall of the desublimation separation tower shell, a top H2 outlet is arranged at the top of the desublimation separation tower shell, and a liquid CO2 outlet is arranged at the bottom of the desublimation separation tower shell; the first to fourth valves and the cooling unit are respectively connected to the control system;

[0048] An inlet filter is provided before the inlet of the second valve; an outlet filter is provided at the H2 outlet of the condensation and sublimation separation tower; a pressure gauge is provided at the H2 outlet at the top of the condensation and sublimation separation tower; a temperature sensor is provided on the pipeline of the H2 outlet at the top of the condensation and sublimation separation tower; a liquid storage tank is provided at the liquid CO2 outlet of the condensation and sublimation separation tower; safety valves are provided at the H2 outlet at the top of the condensation and sublimation separation tower, and the pressure gauge, temperature sensor, liquid collection tank and safety valve are respectively connected to the control system;

[0049] The triple-helix heat exchange tube includes: an H2 tube, an initial mixed gas tube and a cold flow tube, wherein the H2 tube, the initial mixed gas tube and the cold flow tube are tightly fitted in a spiral form, such as Figure 2 As shown; the inlet of the H2 tube is connected to the H2 inlet of the desublimation separation tower, the outlet of the H2 tube is connected to the side wall H2 outlet of the desublimation separation tower, the inlet of the initial mixed gas tube is connected to the initial mixed gas inlet of the desublimation separation tower, the outlet of the initial mixed gas tube is connected to the initial mixed gas outlet of the desublimation separation tower, the inlet of the cold flow tube is connected to the cold supply inlet of the desublimation separation tower, and the outlet of the cold flow tube is connected to the cold return outlet of the desublimation separation tower;

[0050] The low-proportion mixed gas is connected to the inlet of the first valve through a pipeline, and the outlet of the first valve is connected to the low-proportion mixed gas inlet of the condensation and sublimation separation tower; the initial mixed gas is connected to the inlet of the second valve through a pipeline, and the outlet of the second valve is connected to the initial mixed gas inlet of the condensation and sublimation separation tower; the outlet of the refrigeration unit is connected to the inlet of the third valve, and the outlet of the third valve is connected to the refrigeration inlet of the condensation and sublimation separation tower; the top H2 outlet of the condensation and sublimation separation tower is connected to the H2 inlet of the condensation and sublimation separation tower; the side wall return cooling fluid outlet of the condensation and sublimation separation tower is connected to the inlet of the fourth valve, and the outlet of the fourth valve is connected to the inlet of the refrigeration unit through a pipeline; the side wall H2 outlet of the condensation and sublimation separation tower is output through a pipeline; the initial mixed gas outlet of the condensation and sublimation separation tower is transported to the liquefaction separation system through a pipeline; the liquid CO2 outlet of the condensation and sublimation separation tower is output through a pipeline.

[0051] Reliable material selection and flexible process switching also ensure the long-term stable operation of the process. The shell side of the condensation and sublimation separation tower belongs to the category of pressure vessels, with a design pressure of 8.8MPa, a working pressure of 8MPa, a working temperature of -88℃, and a design temperature of -100℃. This low-temperature environment places extremely high demands on materials and structural design. The main component of the separation gas is H2, and hydrogen embrittlement corrosion may occur in extreme cases. Therefore, all equipment and pipelines are made of S30408 ​​material with excellent low-temperature and corrosion resistance to ensure that the equipment can still work stably at low temperatures. In order to ensure the safety of the equipment under high pressure and low temperature environments, the condensation and sublimation separation tower strictly calculates and verifies the shell thickness in accordance with the GB150 "Pressure Vessel" standard to determine the appropriate shell thickness, which not only ensures the strength of the equipment but also reduces its weight. The heat exchanger part is designed according to the GB151 "Heat Exchanger" standard, and the heat exchange capacity of the equipment is calculated. Through reasonable thermal design and fluid dynamics analysis, it is ensured that the equipment can achieve efficient heat exchange in a short time, thereby meeting the heat transfer requirements in the production process.

[0052] The low-proportion mixed gas after liquefaction separation enters the desublimation separation tower for further separation, and the desublimation separation tower performs melting or desublimation:

[0053] The initial mixed gas pressure of supercritical CO2 and H2 is 8MPa and the temperature is 40℃. After liquefaction separation, the CO2 concentration in the mixed gas is reduced to below 15%. The CO2 liquefaction temperature at this concentration is lower than the sublimation temperature. At this time, it enters the continuous sublimation separation system for further separation, and the sublimation separation tower is used for melting or sublimation.

[0054] When the sublimation separation tower is sublimating, the first valve is opened, the second valve is closed, the third valve is opened, and the fourth valve is opened at the same time; the pressure of the low-proportion CO2 and H2 mixed gas after liquefaction separation is 8MPa and the temperature is -52°C. After entering the sublimation separation tower, after heat exchange with the low-temperature H2 and the external cooling energy, the sublimation temperature is -88°C. When the temperature drops to -88°C, the CO2 in the mixed gas is attached to the surface of the heat exchange tube in a solid form; the low-proportion mixed gas enters the sublimation separation tower from the low-proportion mixed gas inlet of the sublimation separation tower through the first valve, which is located outside the triple-helix structure heat exchange tube; at the same time, the cooling fluid from the cooling unit enters the cooling inlet of the sublimation separation tower through the third valve located in the three spiral structure heat exchange tubes in the sublimation separation tower. Cold flow tube of the spiral structure heat exchange tube; the low-proportion mixed gas located outside the triple-helix structure heat exchange tube exchanges heat with the cooling fluid from the refrigeration unit located in the cold flow tube of the triple-helix structure heat exchange tube in the condensation and sublimation separation tower, and the liquid CO2 in the low-proportion mixed gas condenses and adheres to the outer wall of the triple-helix structure heat exchange tube, and the separated gaseous H2 flows out from the H2 outlet at the top of the condensation and sublimation separation tower, and enters the H2 tube of the triple-helix structure heat exchange tube located in the condensation and sublimation separation tower from the H2 inlet of the condensation and sublimation separation tower. After the cold energy carried is recycled, the high-purity H2 flows out of the condensation and sublimation separation tower from the H2 outlet on the side wall through the H2 tube of the triple-helix structure heat exchange tube and is output from the condensation and sublimation separation system to obtain a separated high-purity H2 product.

[0055] When the sublimation separation tower is melting, the first valve is closed, the second valve is opened, the third valve is closed, and the fourth valve is closed at the same time; the initial mixed gas carrying heat energy enters the initial mixed gas pipe of the three-helix structure heat exchange tube located in the sublimation separation tower through the second valve from the initial mixed gas inlet of the sublimation separation tower; after the sublimation separation tower has undergone the sublimation separation process in the previous stage, a large amount of solid CO2 is attached to the surface of the three-helix structure heat exchange tube in the sublimation separation tower, and the initial mixed gas carrying heat energy in the initial mixed gas pipe of the three-helix structure heat exchange tube exchanges heat with the solid CO2, and the solid CO2 melts into liquid CO2, and the liquid CO2 flows out from the liquid CO2 outlet at the bottom of the sublimation separation tower to obtain the separated liquid CO2 product.

[0056] When the temperature is higher than the desublimation temperature -88°C, it indicates that the desublimation process is completed, and the desublimation is switched to melting; the first to fourth valves are controlled by the control system to switch the melting or desublimation of the desublimation separation tower to achieve continuous desublimation separation.

[0057] Embodiment 2

[0058] like Figure 3As shown, in this embodiment, the first desublimation separation tower and the second desublimation separation tower are adopted, and the first to fourth valves adopt the first to fourth three-way valves to constitute a continuous desublimation separation system; the first to fourth three-way valves and the refrigeration unit are respectively connected to the control system; the low-proportion mixed gas is connected to the first port of the first three-way valve through a pipeline, the second port of the first three-way valve is connected to the low-proportion mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-proportion mixed gas inlet of the second desublimation separation tower; the initial mixed gas is connected to the first port of the second three-way valve through a pipeline, the second port of the second three-way valve is connected to the initial mixed gas inlet of the first desublimation separation tower, and the third port of the second three-way valve is connected to the initial mixed gas inlet of the second desublimation separation tower; the outlet of the refrigeration unit is connected to the first port of the third three-way valve, the second port of the third three-way valve is connected to the refrigeration inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the refrigeration inlet of the third three-way valve. The three ports are connected to the cooling inlet of the second desublimation separation tower; the top H2 outlet of the first desublimation separation tower is connected to the H2 inlet of the first desublimation separation tower, and the top H2 outlet of the second desublimation separation tower is connected to the H2 inlet of the second desublimation separation tower; the side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, and the side wall cooling fluid outlet of the second desublimation separation tower is connected to the third port of the fourth three-way valve, and the first port of the fourth three-way valve is connected to the inlet of the cooling unit through a pipeline; the side wall H2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total H2 outlet and output through a pipeline, and the initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total initial mixed gas outlet and transported to the liquefaction separation system through a pipeline; the liquid CO2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total liquid CO2 outlet and output through a pipeline.

[0059] The low-ratio mixed gas after liquefaction separation enters the continuous desublimation separation system for further separation, and the desublimation separation tower performs melting or desublimation; when the first desublimation separation tower performs desublimation, the second desublimation separation tower performs melting at the same time, and when the first desublimation separation tower performs melting, the second desublimation separation tower performs desublimation at the same time;

[0060] The control system controls the first to fourth three-way valves to switch the first desublimation separation tower and the second desublimation separation tower to achieve continuous desublimation separation:

[0061] The first desublimation separation tower desublimates while the second desublimation separation tower melts: the first port and the second port of the first three-way valve are opened while the third port is closed, the first port and the third port of the second three-way valve are opened while the second port is closed, the first port and the second port of the third three-way valve are opened while the third port is closed, and the first port and the second port of the fourth three-way valve are opened while the third port is closed; the low-proportion mixed gas enters the first desublimation separation tower from the first port through the second port of the first three-way valve from the low-proportion mixed gas inlet of the first desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the third three-way valve from the cooling inlet of the first desublimation separation tower, and the first desublimation separation tower desublimates; at the same time, the initial mixed gas carrying heat energy enters the heat exchange tube of the second desublimation separation tower from the first port through the third port of the second three-way valve from the initial mixed gas inlet of the second desublimation separation tower, and the second desublimation separation tower melts;

[0062] The first desublimation separation tower melts while the second desublimation separation tower desublimates: open the first port and the third port of the first three-way valve while closing the second port, open the first port and the second port of the second three-way valve while closing the third port, open the first port and the third port of the third three-way valve while closing the second port, open the first port and the third port of the fourth three-way valve while closing the second port; the initial mixed gas carrying heat energy enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the second three-way valve from the initial mixed gas inlet of the first desublimation separation tower, and the first desublimation separation tower is melted; at the same time, the low-proportion mixed gas enters the second desublimation separation tower from the first port through the third port of the first three-way valve from the low-proportion mixed gas inlet of the second desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the second desublimation separation tower from the first port through the third port of the third three-way valve from the cooling inlet of the second desublimation separation tower, and the second desublimation separation tower is desublimated;

[0063] By switching the material flow direction of the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve, the desublimation and melting process of the first desublimation separation tower and the second desublimation separation tower are switched; during the whole process, the cold energy and heat energy carried by the material are used in stages in the heat exchangers at each level, which minimizes the separation energy consumption. The materials include the initial mixed gas, low-proportion mixed gas, H2 and CO2.

[0064] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A desublimation separation tower based on a triple helical heat exchange tube, characterized in that: The desublimation separation tower comprises: a desublimation separation tower shell, a cooling inlet, an H2 inlet, an initial mixed gas inlet, a low-ratio mixed gas inlet, a cooling outlet, a side wall H2 outlet, an initial mixed gas outlet, a top H2 outlet, a liquid CO2 outlet, a triple-helix structure heat exchange tube, a first to a fourth valve, a cooling unit and a control system; wherein the desublimation separation tower shell is a closed shell with a space inside; a cooling inlet, an H2 inlet, an initial mixed gas inlet and a low-ratio mixed gas inlet are arranged on one side wall of the desublimation separation tower shell, a cooling outlet, a side wall H2 outlet and an initial mixed gas outlet are arranged on the other side wall of the desublimation separation tower shell, a top H2 outlet is arranged at the top of the desublimation separation tower shell, and a liquid CO2 outlet is arranged at the bottom of the desublimation separation tower shell; A triple-helix structure heat exchange tube is arranged in the condensation and sublimation separation tower; The triple-helix structure heat exchange tube includes: an H2 tube, an initial mixed gas tube and a cold flow tube, wherein the H2 tube, the initial mixed gas tube and the cold flow tube are tightly fitted in a spiral form; the inlet of the H2 tube is connected to the H2 inlet of the condensation and sublimation separation tower, the outlet of the H2 tube is connected to the side wall H2 outlet of the condensation and sublimation separation tower, the inlet of the initial mixed gas tube is connected to the initial mixed gas inlet of the condensation and sublimation separation tower, the outlet of the initial mixed gas tube is connected to the initial mixed gas outlet of the condensation and sublimation separation tower, the inlet of the cold flow tube is connected to the cooling inlet of the condensation and sublimation separation tower, and the outlet of the cold flow tube is connected to the cooling outlet of the condensation and sublimation separation tower; The low-ratio mixed gas is connected to the inlet of the first valve through a pipeline, and the outlet of the first valve is connected to the low-ratio mixed gas inlet of the condensation and sublimation separation tower; the initial mixed gas is connected to the inlet of the second valve through a pipeline, and the outlet of the second valve is connected to the initial mixed gas inlet of the condensation and sublimation separation tower; the outlet of the refrigeration unit is connected to the inlet of the third valve, and the outlet of the third valve is connected to the refrigeration inlet of the condensation and sublimation separation tower; the top H2 outlet of the condensation and sublimation separation tower is connected to the H2 inlet of the condensation and sublimation separation tower; the side wall return cooling fluid outlet of the condensation and sublimation separation tower is connected to the inlet of the fourth valve, and the outlet of the fourth valve is connected to the inlet of the refrigeration unit through a pipeline; The first to fourth valves and the cooling units are respectively connected to the control system; The low-proportion mixed gas after liquefaction separation enters the desublimation separation tower for further separation, and the desublimation separation tower performs melting or desublimation: When the desublimation separation tower is condensing, the low-proportion mixed gas outside the triple-helix structure heat exchange tube exchanges heat with the cooling fluid from the refrigeration unit in the cold flow tube of the triple-helix structure heat exchange tube in the desublimation separation tower. The triple-helix structure heat exchange tube enables the low-temperature H2 and the cooling fluid to effectively transfer heat to the low-proportion mixed gas to achieve the desublimation of CO2, and the solid CO2 adheres to the surface of the triple-helix structure heat exchange tube; when the desublimation separation tower is melting, a large amount of solid CO2 adheres to the surface of the triple-helix structure heat exchange tube after the previous stage of the desublimation process and exchanges heat with the initial mixed gas carrying heat energy in the initial mixed gas tube of the triple-helix structure heat exchange tube; the H2 tube, the initial mixed gas tube and the cold flow tube exchange heat with the low-proportion mixed gas in the shell during the desublimation and melting process. Heat exchange, the triple helix structure increases the flow distance of the fluid in the condensation and sublimation separation tower, and the heat exchange area of ​​the heat exchange tube is increased, thereby improving the heat exchange efficiency; the fluid flows in the heat exchange tube in a spiral shape, and this flow mode not only enhances the mixing and disturbance of the fluid, but also the fluid in the triple helix heat exchange tube generates a pair of reverse vortex secondary flows due to the centrifugal force, Coriolis force and buoyancy; the existence of this secondary flow significantly improves the heat transfer coefficient of the tube side film, thereby further increasing the heat transfer coefficient, and significantly improving the heat transfer efficiency of the entire triple helix heat exchange tube. In the condensation and sublimation separation of low-proportion mixed gas, the heat energy of the initial mixed gas and the cold energy of H2 are recycled in the melting and condensation processes respectively, reducing the separation energy consumption; When the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation is switched to melting; the first to fourth valves are controlled by the control system to switch the melting or desublimation of the desublimation separation tower to achieve continuous desublimation separation.

2. The desublimation separation tower according to claim 1, characterized in that: The system also includes pressure gauges, which are respectively arranged at the top H2 outlets of the first desublimation separation tower and the second desublimation separation tower to monitor the desublimation separation process by real-time monitoring of the H2 pressure; pressure gauges are respectively arranged at the second port and the third port of the second three-way valve to monitor the pressure of the initial mixed gas in real time, and the pressure gauges are connected to the control system.

3. The desublimation separation tower according to claim 1, characterized in that: It also includes a temperature sensor, which is arranged on the pipes of the top H2 outlets of the first and second desublimation separation towers, and the temperature sensor is connected to the control system to monitor the temperature at the top H2 outlet of the desublimation separation tower in real time; when the desublimation separation tower is desublimating, when the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation must be switched to melting and switched to another desublimation separation tower to continue desublimation.

4. The desublimation separation tower according to claim 1, characterized in that: It also includes safety valves, which are respectively arranged at the top H2 outlets of the first desublimation separation tower and the second desublimation separation tower, and the safety valves are connected to the control system.

5. The desublimation separation tower according to claim 1, characterized in that: A first desublimation separation tower and a second desublimation separation tower are adopted, and the first to fourth valves adopt the first to fourth three-way valves to form a continuous desublimation separation system; the first to fourth three-way valves and the refrigeration unit are respectively connected to the control system; the low-proportion mixed gas is connected to the first port of the first three-way valve through a pipeline, the second port of the first three-way valve is connected to the low-proportion mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-proportion mixed gas inlet of the second desublimation separation tower; the initial mixed gas is connected to the first port of the second three-way valve through a pipeline, the second port of the second three-way valve is connected to the initial mixed gas inlet of the first desublimation separation tower, and the third port of the second three-way valve is connected to the initial mixed gas inlet of the second desublimation separation tower; the outlet of the refrigeration unit is connected to the first port of the third three-way valve, the second port of the third three-way valve is connected to the refrigeration inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the refrigeration inlet of the first desublimation separation tower. To the cooling inlet of the second desublimation separation tower; the top H2 outlet of the first desublimation separation tower is connected to the H2 inlet of the first desublimation separation tower, and the top H2 outlet of the second desublimation separation tower is connected to the H2 inlet of the second desublimation separation tower; the side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, and the side wall cooling fluid outlet of the second desublimation separation tower is connected to the third port of the fourth three-way valve, and the first port of the fourth three-way valve is connected to the inlet of the cooling unit through a pipeline; the side wall H2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total H2 outlet and output through a pipeline, the initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total initial mixed gas outlet, and transported to the liquefaction separation system through a pipeline; the liquid CO2 outlets of the first desublimation separation tower and the second desublimation separation tower are merged into a total liquid CO2 outlet and output through a pipeline.

6. A method for realizing a desublimation separation tower based on a triple helical structure heat exchange tube as claimed in claim 1, characterized in that: The implementation method comprises the following steps: 1) Set up a desublimation separation tower: The H2 tube, the initial mixed gas tube and the cold flow tube are tightly fitted in a spiral form; the inlet of the H2 tube is connected to the H2 inlet of the condensation and sublimation separation tower, the outlet of the H2 tube is connected to the H2 outlet of the side wall of the condensation and sublimation separation tower, the inlet of the initial mixed gas tube is connected to the initial mixed gas inlet of the condensation and sublimation separation tower, the outlet of the initial mixed gas tube is connected to the initial mixed gas outlet of the condensation and sublimation separation tower, the inlet of the cold flow tube is connected to the cooling inlet of the condensation and sublimation separation tower, and the outlet of the cold flow tube is connected to the cooling outlet of the condensation and sublimation separation tower; The low-ratio mixed gas is connected to the inlet of the first valve through a pipeline, and the outlet of the first valve is connected to the low-ratio mixed gas inlet of the condensation and sublimation separation tower; the initial mixed gas is connected to the inlet of the second valve through a pipeline, and the outlet of the second valve is connected to the initial mixed gas inlet of the condensation and sublimation separation tower; the outlet of the refrigeration unit is connected to the inlet of the third valve, and the outlet of the third valve is connected to the refrigeration inlet of the condensation and sublimation separation tower; the top H2 outlet of the condensation and sublimation separation tower is connected to the H2 inlet of the condensation and sublimation separation tower; the side wall return cooling fluid outlet of the condensation and sublimation separation tower is connected to the inlet of the fourth valve, The outlet of the fourth valve is connected to the inlet of the cooling unit through a pipeline; the H2 outlet of the side wall of the condensation and sublimation separation tower is output through a pipeline; the initial mixed gas outlet of the condensation and sublimation separation tower is transported to the liquefaction separation system through a pipeline; the liquid CO2 outlet of the condensation and sublimation separation tower is output through a pipeline; The first to fourth valves and the cooling units are respectively connected to the control system; 2) The low-proportion mixed gas after liquefaction separation enters the desublimation separation tower for further separation, and the desublimation separation tower performs melting or desublimation: During desublimation in the desublimation separation tower, the low-proportion mixed gas outside the triple-helix structure heat exchange tube exchanges heat with the cooling fluid from the cooling unit located in the cold flow tube of the triple-helix structure heat exchange tube in the desublimation separation tower. The triple-helix structure heat exchange tube enables the low-temperature H2 and the cooling fluid to effectively transfer heat to the low-proportion mixed gas, thereby achieving desublimation of CO2, and solid CO2 adheres to the surface of the triple-helix structure heat exchange tube. When the desublimation separation tower is melting, a large amount of solid CO2 adheres to the surface of the triple helix structure heat exchange tube after the desublimation process in the previous stage, and performs heat exchange with the initial mixed gas carrying heat energy in the initial mixed gas tube of the triple helix structure heat exchange tube; The H2 tube, the initial mixed gas tube and the cold flow tube exchange heat with the low-proportion mixed gas in the shell during the condensation and melting process. The triple helix structure increases the flow distance of the fluid in the condensation and sublimation separation tower, and the heat exchange area of ​​the heat exchange tube is increased, thereby improving the heat exchange efficiency; the fluid flows in a spiral shape in the heat exchange tube. This flow mode not only enhances the mixing and disturbance of the fluid, but also the fluid in the triple helix heat exchange tube generates a pair of reverse vortex secondary flows due to the centrifugal force, Coriolis force and buoyancy; the existence of this secondary flow significantly improves the heat transfer coefficient of the tube side film, thereby further increasing the heat transfer coefficient, and significantly improving the heat transfer efficiency of the entire triple helix heat exchange tube. In the condensation and sublimation separation of the low-proportion mixed gas, the heat energy of the initial mixed gas and the cold energy of H2 are recycled in the melting and condensation processes respectively, reducing the separation energy consumption; 3) When the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed, and the desublimation is switched to melting; the first to fourth valves are controlled by the control system to switch the melting or desublimation of the desublimation separation tower to achieve continuous desublimation separation.

7. The implementation method according to claim 6, characterized in that: In step 2), when the desublimation separation tower desublimates, the first valve is opened, the second valve is closed, the third valve is opened, and the fourth valve is opened at the same time; the low-ratio mixed gas enters the desublimation separation tower from the low-ratio mixed gas inlet through the first valve, and is located outside the triple-helix structure heat exchange tube; at the same time, the cooling fluid from the cooling unit enters the cold flow tube located in the triple-helix structure heat exchange tube in the desublimation separation tower from the cooling inlet through the third valve; the low-ratio mixed gas located outside the triple-helix structure heat exchange tube in the desublimation separation tower and the cooling fluid from the cooling unit located in the triple-helix structure heat exchange tube The cooling fluid in the cold flow tube of the spiral structure heat exchange tube undergoes heat exchange, and the liquid CO2 in the low-proportion mixed gas condenses and adheres to the outer wall of the triple-helix structure heat exchange tube, while the separated gaseous H2 flows out from the H2 outlet at the top of the desublimation separation tower, enters the H2 tube of the triple-helix structure heat exchange tube located in the desublimation separation tower from the H2 inlet of the desublimation separation tower, and after the cold energy carried is recycled, the high-purity H2 flows out of the desublimation separation tower from the H2 outlet on the side wall through the H2 tube of the triple-helix structure heat exchange tube and is output from the desublimation separation system to obtain a separated high-purity H2 product.

8. The implementation method according to claim 6, characterized in that: In step 2), when the desublimation separation tower is melting, the first valve is closed, the second valve is opened, the third valve is closed, and the fourth valve is closed at the same time; the initial mixed gas carrying heat energy enters the initial mixed gas pipe of the triple helix structure heat exchange tube located in the desublimation separation tower through the second valve from the initial mixed gas inlet of the desublimation separation tower; after the desublimation separation tower has undergone the desublimation process of the previous stage, a large amount of solid CO2 is attached to the surface of the triple helix structure heat exchange tube in the desublimation separation tower, and the initial mixed gas carrying heat energy in the initial mixed gas pipe of the triple helix structure heat exchange tube exchanges heat with the solid CO2, and the solid CO2 melts into liquid CO2, and the liquid CO2 flows out from the liquid CO2 outlet at the bottom of the desublimation separation tower to obtain a separated liquid CO2 product.

9. The implementation method according to claim 6, characterized in that: In step 3), a temperature sensor is provided on the pipe of the top H2 outlet of the desublimation separation tower, and the temperature sensor is connected to the control system to monitor the temperature at the top H2 outlet of the desublimation separation tower in real time; when the desublimation separation tower desublimates, when the temperature is higher than the desublimation temperature, it indicates that the desublimation process is completed and the desublimation must be switched to melting.

10. The implementation method according to claim 6, characterized in that: A first desublimation separation tower and a second desublimation separation tower are used, and the first to fourth valves are first to fourth three-way valves to form a continuous desublimation separation system; when the first desublimation separation tower is desublimating, the second desublimation separation tower is simultaneously melted, and when the first desublimation separation tower is melted, the second desublimation separation tower is simultaneously desublimated; the first to fourth three-way valves are controlled by a control system to switch the first desublimation separation tower and the second desublimation separation tower, thereby realizing continuous desublimation separation: The first desublimation separation tower desublimates while the second desublimation separation tower melts: the first port and the second port of the first three-way valve are opened while the third port is closed, the first port and the third port of the second three-way valve are opened while the second port is closed, the first port and the second port of the third three-way valve are opened while the third port is closed, and the first port and the second port of the fourth three-way valve are opened while the third port is closed; The low-ratio mixed gas enters the first desublimation separation tower from the first port through the second port of the first three-way valve from the low-ratio mixed gas inlet of the first desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the third three-way valve from the cooling inlet of the first desublimation separation tower, and the first desublimation separation tower performs desublimation; at the same time, the initial mixed gas carrying heat energy enters the heat exchange tube of the second desublimation separation tower from the first port through the third port of the second three-way valve from the initial mixed gas inlet of the second desublimation separation tower, and the second desublimation separation tower performs melting; The first desublimation separation tower melts while the second desublimation separation tower desublimates: the first port and the third port of the first three-way valve are opened while the second port is closed, the first port and the second port of the second three-way valve are opened while the third port is closed, the first port and the third port of the third three-way valve are opened while the second port is closed, and the first port and the third port of the fourth three-way valve are opened while the second port is closed; the initial mixed gas carrying heat energy enters the heat exchange tube in the first desublimation separation tower from the first port through the second port of the second three-way valve from the initial mixed gas inlet of the first desublimation separation tower, and the first desublimation separation tower is melted; at the same time, the low-proportion mixed gas enters the second desublimation separation tower from the first port through the third port of the first three-way valve from the low-proportion mixed gas inlet of the second desublimation separation tower; at the same time, the cooling fluid from the cooling unit enters the heat exchange tube in the second desublimation separation tower from the first port through the third port of the third three-way valve from the cooling inlet of the second desublimation separation tower, and the second desublimation separation tower is desublimated.

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