Continuous desublimation separation system for supercritical CO2-H2 mixed gas and separation method thereof

Abstract

The invention discloses a continuous desublimation separation system for supercritical CO2-H2 mixed gas and a separation method of the continuous desublimation separation system. Through switching of the three-way valve, continuous switching between desublimation of the first desublimation separation tower and desublimation of the second desublimation separation tower is achieved, and continuous desublimation and melting processes are guaranteed; the temperature of H2 at desublimation outlets of the first desublimation separation tower and the second desublimation separation tower is monitored in real time, the desublimation completion condition in the towers can be accurately judged, and the flow is timely switched, so that the whole separation process is accurate and reliable; the whole separation process is carried out under constant pressure, and the stable supply of external cold energy and high-temperature and high-pressure initial mixed gas ensures that the process is carried out stably; cold energy of H2 and heat energy of initial mixed gas are recycled, and the requirement for external work cold energy is effectively lowered; the whole system realizes an efficient, accurate and stable separation process through an efficient heat exchange design, a continuous separation process and an intelligent control means, and the content of CO2 in H2 is reduced to 1%.

Description

Technical Field

[0001] The present invention relates to the field of heat exchangers, and in particular to a supercritical CO 2 -H 2 A continuous desublimation separation system for mixed gases and a separation method thereof. Background Art

[0002] About CO 2 The research on condensation separation mainly focuses on energy consumption and gas-solid separation. The existing solutions either require the addition of power equipment for mechanical stripping, or the introduction of a third substance into the system, which destroys the original binary equilibrium system and causes secondary pollution requiring secondary separation, or the need to increase compression energy consumption, and the accumulated solid CO 2 Particles can cause blockage and inefficiency in the turbine process. 2 and H 2 The research on low-temperature condensation and sublimation separation of mixed gases mainly has the following problems.

[0003] (1) It is impossible to achieve continuous large-scale separation

[0004] Currently, for CO 2 In the study of low-temperature condensation separation, gas-solid separation is difficult to be carried out continuously and on a large scale. In some studies, heating and rotating scraper methods were used to separate solid CO 2 Separation is performed, but the condensation and melting processes cannot be carried out at the same time; the solid CO is separated by rotation 2 , is the CO after it is expanded through the turbine 2 The phase transition is carried out after the solid particles are formed. This process is prone to accumulation and blockage, resulting in the inability to separate the solid CO2 continuously and efficiently. 2 , it is necessary to introduce low-temperature nitrogen into the mixed gas to cool it down on the one hand, and on the other hand, the nitrogen molecules serve as condensation nuclei, thereby making CO 2 Snow melting occurs, but the introduction of nitrogen causes the CO 2 When recycling, CO needs to be separated 2 and N 2 , resulting in greater energy consumption.

[0005] (2) High separation energy consumption and low separation rate

[0006] As a low-temperature separation method, desublimation separation requires lower temperatures to make CO 2 Condensation occurs. At the same time, in the process of gas-solid separation, the use of external heating melting, mechanical energy-driven rotation separation and scraper separation, low-temperature nitrogen snow separation and other methods will cause higher energy consumption, and the energy consumption increases with the increase of separation rate. Summary of the invention

[0007] In view of the problems existing in the above prior art, the present invention proposes a supercritical CO 2 -H 2 Continuous desublimation separation system and separation method of mixed gas, supercritical CO 2 and H 2 The mixed gas is continuously separated by switching between the low-temperature desublimation and melting in the first and second desublimation separation towers, and the cold and hot energy is recycled. The modular and skid-mounted structure can be flexibly customized in factories according to different needs, which helps to reduce economic costs and land costs.

[0008] One object of the present invention is to provide a supercritical CO 2 -H 2 Continuous desublimation separation system for mixed gases.

[0009] The supercritical CO of the present invention 2 -H 2 The continuous desublimation separation system of the mixed gas comprises: a first desublimation separation tower, a second desublimation separation tower, first to fourth three-way valves, a cooling unit and a control system; wherein the first desublimation separation tower and the second desublimation separation tower are respectively provided with a cooling inlet, H 2 Inlet, initial mixed gas inlet and low ratio mixed gas inlet, and a cooling outlet and a side wall H are provided on the other side wall. 2 outlet and the initial mixed gas outlet, with a top H 2 outlet, with liquid CO at the bottom 2 The outlet of the condensation and sublimation separation tower is provided with a heat exchange tube, and the inlet of the heat exchange tube is connected to the cooling inlet, H 2 The inlet and the initial mixed gas inlet, the outlet of the heat exchange tube is connected back to the cold outlet, the side wall H 2 outlet and initial mixed gas outlet; the first to fourth three-way valves and the cooling units are respectively connected to the control system;

[0010] The low-ratio 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-ratio mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-ratio 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 cooling 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 cooling inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the cooling inlet of the second desublimation separation tower; the top H of the first desublimation separation tower 2 The outlet is connected to the H 2Inlet, top of the second desublimation separation tower H 2 The outlet is connected to the H 2 The side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, 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 H of the first desublimation separation tower and the second desublimation separation tower 2 The outlets are combined into one total H 2 The initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are combined into a total initial mixed gas outlet and transported to the liquefaction separation system through pipelines; the liquid CO in the first desublimation separation tower and the second desublimation separation tower are 2 The outlet is combined into a total liquid CO 2 Export and output through pipeline;

[0011] 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;

[0012] 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:

[0013] 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;

[0014] 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;

[0015] 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.

[0016] Furthermore, the invention also includes an inlet filter and an outlet filter, wherein the inlet filter is arranged before the first port of the second three-way valve; the total H of the first desublimation separation tower and the second desublimation separation tower is 2 Export sets the export filter.

[0017] Also includes a pressure gauge, at the top H of the first desublimation separation tower and the second desublimation separation tower 2 Pressure gauges are respectively set at the outlets to monitor the pressure in the condensation and sublimation separation tower in real time. There is no pressurization or depressurization during the process, so the pressure remains unchanged. Pressure gauges are respectively set 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. The pressure gauges are connected to the control system.

[0018] Also included is a temperature sensor at the top H of the first and second desublimation separation towers. 2 A temperature sensor is installed on the outlet pipe, which is connected to the control system to monitor the H at the top of the desublimation separation tower in real time. 2 The temperature at the outlet; when the desublimation separation tower is condensing, 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, in which the total liquid CO in the first desublimation separation tower and the second desublimation separation tower 2 A liquid storage tank is set at the outlet to act as a buffer.

[0020] It also includes a safety valve at the top H of the first desublimation separation tower and the second desublimation separation tower. 2 Safety valves are respectively arranged at the outlets and are connected to the control system.

[0021] The materials include initial mixed gas, low-proportion mixed gas, H 2 and CO 2 .

[0022] The first three-way valve switches the flow direction of the low-proportion mixed gas, the second three-way valve switches the flow direction of the initial mixed gas, the third three-way valve switches the flow direction of the cooling fluid, and the fourth three-way valve switches back to the flow direction of the cold fluid, thereby realizing the switching of the desublimation and melting processes of the first desublimation separation tower and the second desublimation separation tower.

[0023] The heat exchange tubes in the condensation and sublimation separation tower adopt triple helical structure heat exchange tubes, which include H 2 Tube, initial mixing gas tube and cold flow tube, H 2 The tube, the initial mixing gas tube and the cold flow tube are tightly fitted in a spiral form; 2 The inlet of the tube is connected to the H 2 Entrance, H 2 The outlet of the tube is connected to the side wall H of the desublimation separation tower. 2 The inlet of the initial mixed gas pipe is connected to the initial mixed gas inlet of the condensation and sublimation separation tower, the outlet of the initial mixed gas pipe is connected to the initial mixed gas outlet of the condensation and sublimation separation tower, the inlet of the cold flow pipe is connected to the cold supply inlet of the condensation and sublimation separation tower, and the outlet of the cold flow pipe is connected to the cold return outlet of the condensation and sublimation separation tower; 2 The triple helix structure increases the flow distance of the fluid in the desublimation separation tower, and the heat exchange area of ​​the heat exchange tube is also increased, thereby improving the heat exchange efficiency. 2 The external cooling energy can effectively transfer heat to the low-proportion mixed gas to achieve CO 2 The fluid flows in a spiral shape in the heat exchange tube. This special flow mode not only enhances the mixing and disturbance of the fluid, but also 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 heat exchanger. In the low-temperature separation of low-proportion mixed gas, the heat energy and H 2 The cold energy is recycled in the melting and desublimation processes respectively, which greatly reduces the separation energy consumption.

[0024] Another object of the present invention is to provide a supercritical CO 2 -H2 Continuous desublimation separation method for mixed gases.

[0025] The supercritical CO of the present invention 2 -H 2 The continuous desublimation separation method of mixed gas comprises the following steps:

[0026] 1) Continuous desublimation separation system connection:

[0027] The low-ratio 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-ratio mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-ratio 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 cooling 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 cooling inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the cooling inlet of the second desublimation separation tower; the top H of the first desublimation separation tower 2 The outlet is connected to the H 2 Inlet, top of the second desublimation separation tower H 2 The outlet is connected to the H 2 The side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, 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 H of the first desublimation separation tower and the second desublimation separation tower 2 The outlets are combined into one total H 2 The initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are combined into a total initial mixed gas outlet and transported to the liquefaction separation system through pipelines; the liquid CO in the first desublimation separation tower and the second desublimation separation tower are 2 The outlet is combined into a total liquid CO 2 outlet, and output through pipelines; the first to fourth three-way valves and cooling units are respectively connected to the control system;

[0028] 2) 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;

[0029] 3) 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:

[0030] a) The first desublimation separation tower desublimates while the second desublimation separation tower melts:

[0031] Open the first port and the second port of the first three-way valve and close the third port at the same time, open the first port and the third port of the second three-way valve and close the second port at the same time, open the first port and the second port of the third three-way valve and close the third port at the same time, open the first port and the second port of the fourth three-way valve and close the third port at the same time; 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 cooling inlet of the first desublimation separation tower through the first port and the second port of the third three-way valve, and the first desublimation separation tower performs desublimation; the initial mixed gas carrying heat energy enters the heat exchange tube in the second desublimation separation tower from the initial mixed gas inlet of the second desublimation separation tower from the first port through the third port of the second three-way valve, and the second desublimation separation tower performs melting;

[0032] b) The first desublimation separation tower melts while the second desublimation separation tower desublimates:

[0033] Open the first port and the third port of the first three-way valve and close the second port at the same time, open the first port and the second port of the second three-way valve and close the third port at the same time, open the first port and the third port of the third three-way valve and close the second port at the same time, open the first port and the third port of the fourth three-way valve and close the second port at the same time; 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; 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;

[0034] 4) 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 processes 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 utilized in stages in the heat exchangers at each stage, thereby minimizing the separation energy consumption.

[0035] In step 2), desublimation in a desublimation separation tower comprises the following steps:

[0036] The low-ratio mixed gas exchanges heat with the cooling fluid from the cooling unit in the heat exchange tube in the condensation separation tower. The liquid CO in the low-ratio mixed gas 2 Desublimation occurs and adheres to the surface of the heat exchange tube in the desublimation separation tower, and the separated gaseous H 2 From the top of the desublimation separation tower H 2 The outlet flows out to achieve separation, and the separated gaseous H 2 From the desublimation separation tower 2 The heat exchange tubes entering the condensation and sublimation separation tower carry cold energy that is recycled and reused to produce high-purity H 2 From the side wall H 2 The outlet flows out of the desublimation separation tower and outputs the desublimation separation system to obtain separated high-purity H 2 product; the return cooling fluid in the heat exchange tube flows back to the cooling unit from the side wall return cooling fluid outlet through the fourth three-way valve; the condensation form of direct heat exchange of the heat exchange tube is realized through the step-by-step recovery of cold energy.

[0037] The heat exchange tube adopts a triple-helix structure heat exchange tube; when the desublimation separation tower is desublimating, the low-proportion mixed gas enters the desublimation separation tower from the low-proportion mixed gas inlet of the desublimation separation tower through the first three-way 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 desublimation separation tower from the cooling inlet of the desublimation separation tower through the third three-way valve; the low-proportion mixed gas located outside the triple-helix structure heat exchange tube performs heat exchange 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, and the liquid CO in the low-proportion mixed gas is 2 The condensation occurs and adheres to the outer wall of the triple helical heat exchange tube, and the separated gaseous H 2 From the top of the desublimation separation tower H 2 The outlet flows out from the H 2 The entrance enters the H in the triple helical heat exchange tube in the condensation and sublimation separation tower. 2 The cold energy carried by the tube is recycled and reused to produce high-purity H 2 H through triple helical heat exchange tubes 2 The tube is from the side wall H 2 The outlet flows out of the desublimation separation tower and outputs the desublimation separation system to obtain separated high-purity H 2 The return cooling fluid in the cold flow tube of the heat exchange tube flows back to the cooling unit from the side wall return cooling fluid outlet through the fourth three-way valve.

[0038] The desublimation separation tower melting includes the following steps:

[0039] After the condensation and sublimation separation process in the previous stage, a large amount of solid CO is attached to the surface of the heat exchange tube in the condensation and sublimation separation tower. 2The initial mixed gas carrying heat energy and solid CO in the heat exchange tube 2 For heat exchange, solid CO 2 Melting into liquid CO 2 , liquid CO 2 Liquid CO from the bottom of the desublimation separation tower 2 The outlet flows out to obtain separated liquid CO 2 The initial mixed gas whose heat energy is utilized in the heat exchange tube is output from the initial mixed gas outlet of the desublimation separation tower to the desublimation separation system and enters the liquefaction separation system for liquefaction separation, thereby realizing the melting regeneration of the desublimation separation tower; realizing the solid CO2 that enters the heat exchange tube and the surface of the heat exchange tube by utilizing the initial mixed gas 2 Melting form of heat exchange.

[0040] The heat exchange tube adopts a triple-helix structure heat exchange tube; when the desublimation separation tower is melting, the initial mixed gas carrying heat energy enters the initial mixed gas tube of the triple-helix structure heat exchange tube located in the desublimation separation tower through the second three-way valve from the initial mixed gas inlet of the desublimation separation tower; after the desublimation separation tower has gone through the previous stage of the desublimation separation process, a large amount of solid CO is attached to the surface of the triple-helix structure heat exchange tube in the desublimation separation tower. 2 The initial mixed gas carrying heat energy and solid CO in the initial mixed gas tube of the triple helical heat exchange tube 2 For heat exchange, solid CO 2 Melting into liquid CO 2 , liquid CO 2 Liquid CO from the bottom of the desublimation separation tower 2 The outlet flows out to obtain separated liquid CO 2 product.

[0041] In step 3), at the top of the first and second desublimation separation towers, H 2 A temperature sensor is installed on the outlet pipe, which is connected to the control system to monitor the H at the top of the desublimation separation tower in real time. 2 The temperature at the outlet; when the first or second 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 and switched to another desublimation separation tower to continue desublimation.

[0042] Condensation temperature and CO in low-proportion mixed gas 2 The concentration of CO in low-proportion mixed gas is related to 2 The higher the concentration, the higher the condensation temperature. 2 The lower the concentration, the lower the condensation temperature.

[0043] In step 4), the first three-way valve switches the flow direction of the low-proportion mixed gas, the second three-way valve switches the flow direction of the initial mixed gas, the third three-way valve switches the flow direction of the cooling fluid, and the fourth three-way valve switches back to the flow direction of the cold fluid, thereby realizing the switching of the desublimation and melting processes of the first desublimation separation tower and the second desublimation separation tower.

[0044] Advantages of the present invention:

[0045] The present invention realizes the continuous separation process switching between the first desublimation separation tower and the second desublimation separation tower by switching the three-way valve, and realizes the solid CO separation by switching the operating state of the first desublimation separation tower and the second desublimation separation tower. 2 The continuous stripping and melting of solid CO 2 With H 2 Separation, while achieving the cascade utilization of cold energy and heat energy to ensure the continuous desublimation and melting process, through real-time monitoring of the first desublimation separation tower and the second desublimation separation tower desublimation outlet H 2 The temperature can accurately judge the completion of condensation in the tower and switch the process in time, making the whole separation process more accurate and reliable; the whole separation process is carried out under constant pressure, with external cooling energy and high temperature and high pressure supercritical CO 2 and H 2 The stable supply of the initial mixed gas ensures the stable process; for H 2 The cold energy of the original mixed gas and the heat energy of the initial mixed gas are recycled, which minimizes the demand for external cold energy. The entire system realizes an efficient, accurate and stable separation process through efficient heat exchange design, continuous separation process and intelligent control means, 2 CO 2 The content was reduced to 1%.

[0046] Furthermore, the existing condensation method uses liquid nitrogen snow, refrigerator or expansion; the present invention uses the condensation method of direct heat exchange through heat exchange tubes after cold energy step recovery, CO 2 Condensation occurs and adheres to the surface of the heat exchange tube, H 2 When melting, the initial mixed gas enters the heat exchange tube and reacts with the solid CO 2 Heat exchange, CO 2 After melting into liquid, it is discharged from the bottom of the tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The supercritical CO of the present invention 2 -H 2 A schematic diagram of an embodiment of a continuous desublimation separation system for a mixed gas. DETAILED DESCRIPTION

[0048] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0049] like Figure 1 As shown, the supercritical CO 2 -H 2 The continuous desublimation separation system of the mixed gas comprises: a first desublimation separation tower, a second desublimation separation tower, first to fourth three-way valves, a cooling unit, an inlet filter, an outlet filter, a pressure gauge, a liquid collecting tank and a safety valve; wherein the first desublimation separation tower and the second desublimation separation tower are respectively provided with a cooling inlet, H 2 Inlet, initial mixed gas inlet and low ratio mixed gas inlet, and a cooling outlet and a side wall H are provided on the other side wall. 2 outlet and the initial mixed gas outlet, with a top H 2 outlet, with liquid CO at the bottom 2 outlet; an inlet filter is set before the first port of the second three-way valve; the total H of the first desublimation separation tower and the second desublimation separation tower 2 The outlet is provided with an outlet filter; at the top of the first desublimation separation tower and the second desublimation separation tower, H 2 Pressure gauges are respectively set at the outlet; pressure gauges are respectively set 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; the total liquid CO in the first desublimation separation tower and the second desublimation separation tower 2 A liquid storage tank is set at the outlet to play a buffering role; at the top of the first desublimation separation tower and the second desublimation separation tower, H 2 Safety valves are respectively provided at the outlets; H at the tops of the first and second desublimation separation towers respectively 2 The outlet pipeline is provided with a temperature sensor pressure gauge, a safety valve and a temperature sensor which are respectively connected to the control system;

[0050] The low-ratio 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-ratio mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-ratio 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 cooling 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 cooling inlet of the first desublimation separation tower, and the third port of the third three-way valve is connected to the cooling inlet of the second desublimation separation tower; the top H of the first desublimation separation tower 2 The outlet is connected to the H 2 Inlet, top of the second desublimation separation tower H 2 The outlet is connected to the H2 The side wall cooling fluid outlet of the first desublimation separation tower is connected to the second port of the fourth three-way valve, 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 H of the first desublimation separation tower and the second desublimation separation tower 2 The outlets are combined into one total H 2 The initial mixed gas outlets of the first desublimation separation tower and the second desublimation separation tower are combined into a total initial mixed gas outlet and transported to the liquefaction separation system through pipelines; the liquid CO in the first desublimation separation tower and the second desublimation separation tower are 2 The outlet is combined into a total liquid CO 2 Export and output through the 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 separation tower belongs to the category of pressure vessels, with a design pressure of 8.8MPa, an operating pressure of 8MPa, an operating temperature of -88℃, and a design temperature of -100℃. This low temperature environment places extremely high demands on the material and structural design. The main component of the separation gas is H 2 In extreme cases, hydrogen embrittlement corrosion may occur. Therefore, all equipment and pipelines are made of S30408 ​​material with excellent low temperature resistance 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 environment, the condensation 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] Supercritical CO 2 and H 2 The initial mixed gas pressure is 8MPa and the temperature is 40℃. After liquefaction separation, the CO 2 The concentration dropped to below 15%, at which CO 2 The liquefaction temperature is lower than the desublimation temperature. At this time, it enters the continuous desublimation separation system for further separation. 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. When the first desublimation separation tower performs melting, the second desublimation separation tower performs desublimation at the same time.

[0053] Desublimation separation tower desublimation process:

[0054] Low proportion of CO after liquefaction separation2 and H 2 The mixed gas has a pressure of 8 MPa and a temperature of -52°C. After entering the desublimation separation tower, it is mixed with low-temperature H 2 After heat exchange with external cooling energy, the condensation temperature is -88℃. When the temperature drops to -88℃, the CO in the mixed gas 2 The low-ratio mixed gas is attached to the surface of the heat exchange tube in a solid form; the low-ratio mixed gas exchanges heat with the cooling fluid from the cooling unit in the condensation separation tower, and the liquid CO in the low-ratio mixed gas is 2 Desublimation occurs and adheres to the outer wall of the heat exchange tube in the desublimation separation tower, and the separated gaseous H 2 From the top of the desublimation separation tower H 2 The outlet flows out from the H 2 The entrance enters the condensation separation tower, and the cold energy carried is recycled to produce high-purity H 2 From the side wall H 2 The outlet flows out of the desublimation separation tower and outputs the desublimation separation system to obtain separated high-purity H 2 Products; the return cooling fluid of the condensation and sublimation separation tower flows back to the cooling unit from the return cooling fluid outlet of the side wall through the fourth three-way valve; the condensation form of direct heat exchange using heat exchange pipes after the cold energy is recovered in stages;

[0055] Desublimation separation tower melting process:

[0056] Supercritical CO 2 and H 2 The mixed gas passes through liquid CO 2 After pre-cooling, the heat exchanger enters the desublimation separation tower at a temperature of -10°C. After the desublimation separation process in the previous stage, a large amount of solid CO is attached to the surface of the heat exchange tube in the desublimation separation tower. 2， The initial mixed gas carrying heat energy enters the heat exchange tube in the condensation separation tower and the solid CO 2 For heat exchange, solid CO on the surface of the heat exchange tube 2 After absorbing heat, the temperature rises to -20.0℃ and melts into liquid CO 2 , pressure is 8MPa, liquid CO 2 Liquid CO from the bottom of the desublimation separation tower 2 The outlet flows out to obtain separated liquid CO 2 The initial mixed gas whose heat energy is utilized is output from the initial mixed gas outlet of the desublimation separation tower to the desublimation separation system and enters the liquefaction separation system for liquefaction separation, thereby realizing the melting regeneration of the desublimation separation tower; realizing the utilization of the initial mixed gas to enter the heat exchange tube and the solid CO on the surface of the heat exchange tube 2 Melting form of heat exchange.

[0057] When the temperature is higher than the desublimation temperature -88°C, it indicates that the desublimation process is completed. The desublimation must be switched to melting and switched to another desublimation separation tower to continue desublimation. 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:

[0058] 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 of the second three-way valve 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 three-way valve from the first port, and the low-proportion mixed gas enters the first desublimation separation tower from the low-proportion mixed gas inlet of the first desublimation separation tower through the second port of the first three-way valve; at the same time, the cooling fluid from the cooling unit enters the first port of the third three-way valve, and the cooling fluid enters the first desublimation separation tower from the cooling inlet of the first desublimation separation tower through the second port of the third three-way valve, and the first desublimation separation tower desublimates; the initial mixed gas carrying heat energy enters the heat exchange tube of the second desublimation separation tower from the initial mixed gas inlet of the second desublimation separation tower through the third port of the second three-way valve, and the second desublimation separation tower melts;

[0059] 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 of the second three-way valve 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 three-way valve and from the initial mixed gas inlet of the first desublimation separation tower, and the first desublimation separation tower is melted; the low-proportion mixed gas enters the second desublimation separation tower from the first port through the first three-way valve and 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 and from the cooling inlet of the second desublimation separation tower, and the second desublimation separation tower is desublimated;

[0060] The first three-way valve switches the flow direction of the low-proportion mixed gas, the second three-way valve switches the flow direction of the initial mixed gas, the third three-way valve switches the flow direction of the cooling fluid, and the fourth three-way valve switches back to the flow direction of the cold fluid, thereby realizing the switching of the desublimation and melting processes of the first desublimation separation tower and the second desublimation separation tower; during the whole process, the cold energy and heat energy carried by the material are utilized in a cascade manner in each stage of the heat exchanger, thereby minimizing the separation energy consumption.

[0061] 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 continuous desublimation separation system for supercritical CO2-H2 mixed gas, characterized in that: The continuous desublimation separation system comprises: a first desublimation separation tower, a second desublimation separation tower, first to fourth three-way valves, a refrigeration unit and a control system; wherein the first desublimation separation tower and the second desublimation separation tower are respectively provided with a refrigeration inlet, a H2 inlet, an initial mixed gas inlet and a low-proportion mixed gas inlet on one side wall, a return cooling outlet, a side wall H2 outlet and an initial mixed gas outlet on the other side wall, a top H2 outlet is provided at the top, and a liquid CO2 outlet is provided at the bottom; a heat exchange tube is provided in the desublimation separation tower, the inlet of the heat exchange tube is connected to the refrigeration inlet, the H2 inlet and the initial mixed gas inlet, and the outlet of the heat exchange tube is connected to the return cooling outlet, the side wall H2 outlet and the initial mixed gas outlet; the first to fourth three-way valves and the refrigeration unit are respectively connected to the control system; The low-ratio 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-ratio mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-ratio 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 second desublimation separation tower; the top H2 outlet of the first desublimation separation tower is connected to the first desublimation separation tower; The H2 inlet of the separation tower, 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, 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 refrigeration 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; 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; 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; 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 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.

2. The continuous desublimation separation system according to claim 1, characterized in that: 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.

3. The continuous desublimation separation system according to claim 1, characterized in that: 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; 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.

4. The continuous desublimation separation system according to claim 1, characterized in that: 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.

5. The continuous desublimation separation system 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.

6. The continuous desublimation separation system according to claim 1, characterized in that: The heat exchange tube adopts a triple-helix structure heat exchange tube, which includes an H2 tube, an initial mixed gas tube and a cold flow tube. 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 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 cooling inlet of the desublimation separation tower, and the outlet of the cold flow tube is connected to the cooling return outlet of the desublimation separation tower; the H2 tube, the initial mixed gas tube and the cold flow tube perform heat exchange with the low-proportion mixed gas in the shell during the desublimation and melting process.

7. A continuous desublimation separation method of a supercritical CO2-H2 mixed gas as claimed in claim 1, characterized in that: The continuous desublimation separation method comprises the following steps: 1) Continuous desublimation separation system connection: The low-ratio 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-ratio mixed gas inlet of the first desublimation separation tower, and the third port of the first three-way valve is connected to the low-ratio 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 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; 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 refrigeration 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; the first to fourth three-way valves and the refrigeration unit are respectively connected to the control system; 2) 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; 3) 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: a) The first desublimation separation tower desublimates while the second desublimation separation tower melts: Open the first port and the second port of the first three-way valve and close the third port at the same time, open the first port and the third port of the second three-way valve and close the second port at the same time, open the first port and the second port of the third three-way valve and close the third port at the same time, open the first port and the second port of the fourth three-way valve and close the third port at the same time; 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 cooling inlet of the first desublimation separation tower through the first port and the second port of the third three-way valve, and the first desublimation separation tower performs desublimation; the initial mixed gas carrying heat energy enters the heat exchange tube in the second desublimation separation tower from the initial mixed gas inlet of the second desublimation separation tower from the first port through the third port of the second three-way valve, and the second desublimation separation tower performs melting; b) 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 and close the second port at the same time, open the first port and the second port of the second three-way valve and close the third port at the same time, open the first port and the third port of the third three-way valve and close the second port at the same time, open the first port and the third port of the fourth three-way valve and close the second port at the same time; 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; 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, The second desublimation separation tower performs desublimation; 4) 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 processes 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 utilized in stages in the heat exchangers at each stage, thereby minimizing the separation energy consumption.

8. The continuous desublimation separation method according to claim 7, characterized in that: In step 2), desublimation in the desublimation separation tower includes the following steps: a low-proportion mixed gas exchanges heat with a cooling fluid from a cooling unit in a heat exchange tube in the desublimation separation tower, liquid CO2 in the low-proportion mixed gas condenses and adheres to the surface of the heat exchange tube in the desublimation separation tower, and the separated gaseous H2 flows out from the H2 outlet at the top of the desublimation separation tower to achieve separation, the separated gaseous H2 enters the heat exchange tube 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 and outputs the desublimation separation system to obtain a separated high-purity H2 product; the return cooling fluid in the heat exchange tube flows back to the cooling unit from the return cooling fluid outlet on the side wall through the fourth three-way valve; the desublimation form of direct heat exchange through the heat exchange tube is achieved through stepwise recovery of cold energy.

9. The continuous desublimation separation method according to claim 7, characterized in that: In step 2), the melting of the desublimation separation tower includes the following steps: after the desublimation separation tower has undergone the desublimation separation process in the previous stage, a large amount of solid CO2 is attached to the surface of the heat exchange tube in the desublimation separation tower, the initial mixed gas carrying heat energy in the 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; the initial mixed gas whose heat energy is utilized in the heat exchange tube is output from the initial mixed gas outlet of the desublimation separation tower to the desublimation separation system and enters the liquefaction separation system for liquefaction separation, thereby realizing the melting regeneration of the desublimation separation tower; and realizing the melting form of heat exchange between the solid CO2 entering the heat exchange tube and the surface of the heat exchange tube using the initial mixed gas.

10. The continuous desublimation separation method according to claim 7, characterized in that: In step 4), the first three-way valve switches the medium flow direction of the low-proportion mixed gas, the second three-way valve switches the medium flow direction of the initial mixed gas, the third three-way valve switches the medium flow direction of the cooling fluid, and the fourth three-way valve switches back to the medium flow direction of the cold fluid, thereby realizing the switching of the desublimation and melting processes of the first desublimation separation tower and the second desublimation separation tower.

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