A medium and low pressure liquefied carbon dioxide storage tank coexisting evaporation gas control system

Abstract

The application discloses a kind of medium pressure and low pressure liquefied carbon dioxide storage tank coexistence evaporation gas control system, and the terminal for storing liquefied carbon dioxide is simultaneously provided with medium pressure liquefied carbon dioxide storage tank and low pressure liquefied carbon dioxide storage tank, first liquid cargo pump is arranged in the medium pressure liquefied carbon dioxide storage tank, and second liquid cargo pump is arranged in the low pressure liquefied carbon dioxide storage tank;First liquid cargo pump is connected with the spray pipeline in the medium pressure liquefied carbon dioxide storage tank in sequence through pipeline, and the first heat exchanger is connected with the spray pipeline in the low pressure liquefied carbon dioxide storage tank through pipeline.Second liquid cargo pump is connected with the first heat exchanger and the second heat exchanger respectively through three-way valve, and the second heat exchanger is connected with refrigerant compressor and third heat exchanger in sequence, and refrigeration cycle is formed.Third heat exchanger is connected with the second heat exchanger through pipeline, and third heat exchanger is connected with seawater system.The application can realize evaporation gas control of different pressure storage tank using a set of equipment, and has the characteristics of energy saving, safety and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding and design, and specifically relates to an evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks. Background Technology

[0002] With the continuous advancement of global carbon sequestration technology, marine carbon sequestration is increasingly favored by countries around the world due to its advantages such as high security, good source / sink compatibility, and great carbon reduction potential.

[0003] Because the triple point pressure of carbon dioxide (4.18 barg) is higher than 1 atmosphere, it cannot be liquefied using a completely refrigerated method during its storage and transportation at sea. Instead, it must be pressurized above the triple point pressure and stored in pressurized C-type tanks to prevent the liquefied carbon dioxide from solidifying into dry ice. Depending on the pressure, there are two main technical solutions for liquefied carbon dioxide storage: low-pressure (-55℃, 8 barg) and medium-pressure (-35℃, 19 barg). The low-pressure solution has lower construction costs for the liquefied carbon dioxide transport ships and storage facilities. While the medium-pressure solution has higher equipment costs, its overall operating costs (from capture to storage) are relatively lower from a supply chain perspective. Therefore, both pressure solutions have market demand, and in the future, carbon dioxide transport ships or storage facilities compatible with both medium-pressure and low-pressure solutions will emerge.

[0004] Currently, there is no evaporation gas control system in the world suitable for the coexistence of medium-pressure and low-pressure liquefied carbon dioxide storage tanks for this application scenario. Considering the safety of liquefied carbon dioxide storage and the efficient use of energy, there is an urgent need to develop an evaporation gas control system suitable for the coexistence of medium-pressure and low-pressure liquefied carbon dioxide storage tanks. Summary of the Invention

[0005] To solve the above problems, the present invention provides a pile leg side tube tilting device, the technical solution of which is as follows: An evaporative gas control system with both medium-pressure and low-pressure liquefied carbon dioxide storage tanks is disclosed. The liquefied carbon dioxide storage terminal is equipped with both a medium-pressure liquefied carbon dioxide storage tank and a low-pressure liquefied carbon dioxide storage tank. A first liquid pump is installed in the medium-pressure liquefied carbon dioxide storage tank, and a second liquid pump is installed in the low-pressure liquefied carbon dioxide storage tank. The first liquid pump is connected to the hot end inlet of a first heat exchanger via a pipeline. The hot end outlet of the first heat exchanger is connected to a spray line inside the medium-pressure liquefied carbon dioxide storage tank via a pipeline. The cold end outlet of the first heat exchanger is connected to a spray line inside the low-pressure liquefied carbon dioxide storage tank via a pipeline.

[0006] The second liquid pump is connected to a branch of a three-way valve. The main branch of the three-way valve is connected to the cold end inlet of the first heat exchanger and the hot end inlet of the second heat exchanger. The hot end outlet of the second heat exchanger is connected to the refrigerant compressor and the hot end inlet of the third heat exchanger in sequence to form a refrigeration cycle.

[0007] The hot end outlet of the third heat exchanger is connected to the cold end inlet of the second heat exchanger via a pipeline. The cold end outlet and cold end inlet of the third heat exchanger are connected to the seawater system.

[0008] Furthermore, in the aforementioned evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, the three-way valve is a pressure control valve. The valve opening is controlled by a pressure sensor installed at the hot end outlet of the first heat exchanger, thereby regulating the flow rate of liquefied carbon dioxide flowing through the first heat exchanger.

[0009] Furthermore, the aforementioned evaporator control system, which combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, further utilizes R407 as an intermediate refrigerant in its refrigeration cycle.

[0010] Furthermore, in the aforementioned evaporative gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, multiple medium-pressure or low-pressure liquefied carbon dioxide storage tanks are simultaneously installed within the liquefied carbon dioxide storage terminal, with the multiple medium-pressure liquefied carbon dioxide storage tanks connected in parallel and the multiple low-pressure liquefied carbon dioxide storage tanks connected in parallel.

[0011] Furthermore, in the aforementioned evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, a throttling valve is installed on the passage from the hot end outlet of the third heat exchanger to the cold end inlet of the second heat exchanger.

[0012] Furthermore, in the aforementioned evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, a pressure sensor is installed on the pipeline connecting the hot end outlet of the first heat exchanger to the spray pipeline inside the medium-pressure liquefied carbon dioxide storage tank.

[0013] This invention utilizes a single refrigeration system to simultaneously control the evaporation rate of liquefied carbon dioxide in both medium-pressure and low-pressure liquefied carbon dioxide storage tanks, reducing the risk of overpressure within the tanks and offering the advantage of low investment cost. Furthermore, it leverages the cooling energy of the low-pressure liquefied carbon dioxide to cool the medium-pressure liquefied carbon dioxide, improving energy utilization efficiency and achieving significant energy conservation and emission reduction effects. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the system of the present invention; Among them, 1-liquefied carbon dioxide storage terminal, 2-medium-pressure liquefied carbon dioxide storage tank, 3-low-pressure liquefied carbon dioxide storage tank, 4-first liquid cargo pump, 5-second liquid cargo pump, 6-first heat exchanger, 7-second heat exchanger, 8-refrigerant compressor, 9-third heat exchanger, 10-throttle valve, 11-three-way valve, 12-pressure sensor. Detailed Implementation

[0015] The invention will be further described with reference to the accompanying drawings.

[0016] An evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, such as... Figure 1 As shown, the liquefied carbon dioxide storage terminal 1 is equipped with both a medium-pressure liquefied carbon dioxide storage tank 2 and a low-pressure liquefied carbon dioxide storage tank 3. The medium-pressure liquefied carbon dioxide storage tank 2 has a design pressure of 19 barg and a design temperature of -35℃; the low-pressure liquefied carbon dioxide storage tank 3 has a design pressure of 8 barg and a design temperature of -55℃. The first liquid pump 4 and the second liquid pump 5 are variable frequency control pumps, and the outlet pressure and flow rate of the medium are adjustable.

[0017] During the operation of the liquefied carbon dioxide storage terminal 1, the medium-pressure liquefied carbon dioxide storage tank 2 absorbs heat from the outside, causing the liquefied carbon dioxide stored inside to vaporize, resulting in an increase in pressure and temperature inside the tank. When the pressure inside the tank reaches the preset pressure (preferably 17.2 barg), the first liquid pump 4 is started to transfer the liquefied carbon dioxide in the medium-pressure liquefied carbon dioxide storage tank 2 to the hot end of the first heat exchanger 6 through pipeline 001; at the same time, the second liquid pump 5 is started to transfer the liquefied carbon dioxide in the low-pressure liquefied carbon dioxide storage tank 3 to the cold end of the first heat exchanger 6 through pipeline 004, three-way valve 11 and pipeline 005, using the temperature difference between the two to cool the medium-pressure liquefied carbon dioxide.

[0018] The low-pressure liquefied carbon dioxide heated in the first heat exchanger 6 is transferred through pipelines 006 and 007 to a spray pipe 008 installed at the top of the low-pressure liquefied carbon dioxide storage tank 3, and then re-sprayed into the low-pressure liquefied carbon dioxide storage tank 3. The cooled medium-pressure liquefied carbon dioxide is transferred through pipeline 002 to a spray pipe 003 installed at the top of the medium-pressure liquefied carbon dioxide storage tank 2, and then re-sprayed into the medium-pressure liquefied carbon dioxide storage tank 2, reducing the pressure and temperature inside the tank, thereby controlling the evaporation rate of liquefied carbon dioxide.

[0019] When the pressure inside the low-pressure liquefied carbon dioxide storage tank 3 reaches the preset pressure (preferably 7.2 barg), the three-way valve 11 is adjusted to allow a portion of the low-pressure liquefied carbon dioxide to be transferred through pipeline 009 to the hot end of the second heat exchanger 7. Simultaneously, the refrigeration cycle is started, allowing the refrigerant to be transferred through the refrigerant compressor 8 and pipeline 012 to the third heat exchanger 9. After exchanging heat with seawater, the refrigerant passes through pipeline 013 to the throttle valve 10 for pressure and temperature reduction, and then through pipeline 014 to the cold end of the second heat exchanger 7 to cool the low-pressure liquefied carbon dioxide. R407 is used as the intermediate refrigerant in the refrigeration cycle.

[0020] The refrigerant heated in the second heat exchanger 7 returns to the refrigerant compressor 8 via pipeline 011. The cooled low-pressure liquefied carbon dioxide is mixed with the higher-temperature low-pressure liquefied carbon dioxide in pipeline 006 via pipeline 010, and then transmitted via pipeline 007 to the spray pipe 008 installed at the top of the low-pressure liquefied carbon dioxide storage tank 3, where it is sprayed back into the tank to reduce the pressure and temperature, thereby controlling the evaporation rate of liquefied carbon dioxide.

[0021] Pipelines 015 and 016 connect to the seawater system, providing cooling energy for this system. Three-way valve 11 is a pressure-controlled valve; its opening is controlled by pressure sensor 12, thereby distributing the flow of low-pressure liquefied carbon dioxide to the first heat exchanger 6 and the second heat exchanger 7. Specifically, when the pressure sensor 12 reading is high (close to 17.2 barg), the flow rate of low-pressure liquefied carbon dioxide in pipeline 005 is increased, and vice versa.

Claims

1. An evaporation gas control system that combines medium-pressure and low-pressure liquefied carbon dioxide storage tanks, characterized in that, The liquefied carbon dioxide storage terminal is equipped with both a medium-pressure liquefied carbon dioxide storage tank and a low-pressure liquefied carbon dioxide storage tank. The medium-pressure liquefied carbon dioxide storage tank is equipped with a first liquid pump, and the low-pressure liquefied carbon dioxide storage tank is equipped with a second liquid pump. The first liquid pump is connected to the hot end inlet of a first heat exchanger via a pipeline. The hot end outlet of the first heat exchanger is connected to the spray pipeline in the medium-pressure liquefied carbon dioxide storage tank via a pipeline. The cold end outlet of the first heat exchanger is connected to the spray pipeline in the low-pressure liquefied carbon dioxide storage tank via a pipeline. The second liquid pump is connected to the branch of the three-way valve. The main branch of the three-way valve is connected to the cold end inlet of the first heat exchanger and the hot end inlet of the second heat exchanger. The hot end outlet of the second heat exchanger is connected to the refrigerant compressor and the hot end inlet of the third heat exchanger in sequence to form a refrigeration cycle. The hot end outlet of the third heat exchanger is connected to the cold end inlet of the second heat exchanger via a pipeline. The cold end outlet and cold end inlet of the third heat exchanger are connected to the seawater system.

2. The evaporation gas control system for a combination of medium-pressure and low-pressure liquefied carbon dioxide storage tanks according to claim 1, characterized in that, The three-way valve is a pressure control valve. The valve opening is controlled by a pressure sensor installed at the hot end outlet of the first heat exchanger, thereby regulating the flow rate of liquefied carbon dioxide flowing through the first heat exchanger.

3. The evaporation gas control system for a medium-pressure and low-pressure liquefied carbon dioxide storage tank as described in claim 1, characterized in that, The refrigeration cycle uses R407 as the intermediate refrigerant.

4. The evaporation gas control system for a combination of medium-pressure and low-pressure liquefied carbon dioxide storage tanks according to claim 1, characterized in that, The liquefied carbon dioxide storage terminal is equipped with multiple medium-pressure liquefied carbon dioxide storage tanks or low-pressure liquefied carbon dioxide storage tanks. Multiple medium-pressure liquefied carbon dioxide storage tanks are connected in parallel, and multiple low-pressure liquefied carbon dioxide storage tanks are connected in parallel.

5. The evaporation gas control system for a combination of medium-pressure and low-pressure liquefied carbon dioxide storage tanks according to claim 1, characterized in that, A throttling valve is installed on the passage from the hot end outlet of the third heat exchanger to the cold end inlet of the second heat exchanger.

6. The evaporation gas control system for the coexistence of medium-pressure and low-pressure liquefied carbon dioxide storage tanks according to claim 1, characterized in that, A pressure sensor is installed on the pipeline connecting the hot end outlet of the first heat exchanger to the spray pipeline inside the medium-pressure liquefied carbon dioxide storage tank.

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