Scheme for sharing one set of liquid cargo system by multiple liquid CO2 storage tanks

Abstract

A scheme that a plurality of liquid CO2 storage tanks share one set of liquid cargo system comprises a plurality of liquid CO2 storage tanks, and the plurality of liquid CO2 storage tanks are communicated with one another through connecting pipelines and share one set of liquid cargo system. A plurality of loading branch pipelines extend out of the loading main pipeline and respectively extend into the liquid CO2 storage tanks, the other end of the loading main pipeline is connected with a loading system or an unloading system, a liquid cargo unloading pump is arranged in one of the liquid CO2 storage tanks, and the liquid cargo unloading pump is connected with the loading main pipeline through an unloading pipeline. A plurality of liquid CO2 singing devices share one set of sweeping system, the top of each liquid CO2 storage tank is provided with a boil-off gas branch pipeline, the boil-off gas branch pipelines are gathered to a boil-off gas main pipeline to enter the CO2 low-temperature and low-pressure liquefaction skid, and the boil-off gas branch pipelines are treated by the CO2 low-temperature and low-pressure liquefaction skid and then return to each liquid CO2 storage tank. The system configuration is reduced through system sharing, especially the number of liquid cargo pumps is greatly reduced, and the purchase cost of ship related systems is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of marine ship design and construction, and in particular relates to a solution in which a plurality of liquid CO2 storage tanks share a liquid cargo system. Background Art

[0002] In order to alleviate and improve the global climate change problem, countries around the world are studying how to solve the carbon dioxide emissions from production and life. In recent years, with the continuous deepening of research, carbon capture, utilization and storage has emerged as a new industry.

[0003] Carbon capture, utilization and storage refers to the industrial process of separating carbon dioxide (CO2) from industrial emission sources and directly utilizing or storing it to achieve CO2 emission reduction.

[0004] Carbon capture, utilization and storage technology is an emerging technology with the potential for large-scale carbon dioxide emission reduction. It is expected to achieve low-carbon utilization of fossil energy and is widely regarded as one of the important technologies for addressing global climate change and controlling greenhouse gas emissions.

[0005] Given the important role of carbon capture, utilization and storage technology in addressing climate change and carbon emission reduction, developed countries in Europe and the United States have been exploring giving carbon capture, utilization and storage technology the same policy support as other clean energy sources to accelerate the industrialization of carbon capture, utilization and storage technology.

[0006] From the perspective of my country's carbon emission reduction needs to achieve its goals, according to current technology development forecasts, in 2050 and 2060, the emission reductions required through carbon capture, utilization and storage technology are 600 million to 1.4 billion tons and 100 million to 180 million tons of carbon dioxide respectively. As the ocean is the most suitable place for carbon dioxide storage, strengthening the research and development of marine carbon storage related equipment has become a key task for carbon treatment companies at home and abroad in recent years.

[0007] However, the current carbon capture, utilization and storage technology still has prominent problems such as high cost. Among them, the construction cost of carbon dioxide transport ships and carbon dioxide storage ships is a core issue affecting the initial investment of carbon capture, utilization and storage related industries. The construction cost of these two types of ships is directly related to whether the entire industrial chain can proceed normally. How to reduce the construction cost of carbon transport ships and carbon dioxide storage ships has become a matter of great concern to the industry and even relevant national departments.

[0008] However, due to the high investment cost of this type of ship, it is still only in a small-scale experimental development and cannot be carried out on a large scale. The core cost of carbon dioxide transport ships and carbon dioxide storage ships is mainly reflected in the liquid CO2 storage tanks and the supporting liquid cargo systems.

[0009] In order to reduce the cost of the CO2 tank liquid cargo system, when developing this type of ship, super-large liquid CO2 storage tanks are basically used to reduce the number of liquid CO2 storage tanks. This solution reduces the total cost of the ship's liquid CO2 storage tank liquid cargo system.

[0010] However, due to the increase in the volume of the storage tank, the volume and weight of a single tank have increased significantly, and the weight of a single tank has exceeded 1,000 tons. For such a huge storage tank, whether it is pre-construction or post-installation, due to its large volume and weight, there are very few shipyards that can meet the construction and installation of such a tank, which greatly increases the construction and installation costs of the tank. And the increase may exceed the reduction in the cost of the liquid cargo system. Therefore, the effect of reducing the comprehensive cost of the ship by increasing the volume of the storage tank and reducing the number of liquid cargo systems is not obvious.

[0011] In summary, how to reduce the construction cost of ships used to transport and store captured carbon dioxide and reduce investors' investment has become a difficulty in the industrialization of CO2 offshore storage technology. Summary of the invention

[0012] In order to solve the above problems, the present invention provides a solution for multiple liquid CO2 storage tanks to share a liquid cargo system, and the technical solution adopted is: Multiple liquid CO2 storage tanks share a liquid cargo system. There are multiple liquid CO2 storage tanks. Overflow wells are arranged at the bottom of the multiple liquid CO2 storage tanks. Adjacent overflow wells are interconnected through connecting pipelines. Multiple connecting pipeline isolation valves are arranged on the connecting pipelines at the overflow well mouths. The multiple connecting pipeline isolation valves control the various flow directions of the liquid. A plurality of loading branch pipelines extend from the loading main pipeline and extend into each liquid CO2 storage tank respectively. The other end of the loading main pipeline is connected to the loading system or the unloading system. A liquid cargo unloading pump is arranged in one of the liquid CO2 storage tanks, and the liquid cargo unloading pump is connected to the loading main pipeline through the unloading pipeline.

[0013] A plurality of stripping branch pipelines extend from the CO2 stripping main pipeline and extend into each liquid CO2 storage tank respectively, and are connected to the stripping pumps in each liquid CO2 storage tank.

[0014] A boil-off gas branch pipeline is arranged on the top of each liquid CO2 storage tank. The boil-off gas branch pipelines are collected into the boil-off gas main pipeline, and enter the CO2 low-temperature and low-pressure liquefaction skid through the boil-off gas main pipeline. After being processed by the CO2 low-temperature and low-pressure liquefaction skid, the gas returns to each liquid CO2 storage tank through the loading branch pipeline.

[0015] A plurality of tank stripping system isolation valves are arranged on the CO2 tank stripping main line, and the flow of liquid CO2 storage tanks during the tank stripping process is controlled by opening and closing the plurality of tank stripping system isolation valves.

[0016] The above-mentioned multiple liquid CO2 storage tanks share a liquid cargo system solution. Furthermore, the CO2 low-temperature and low-pressure liquefaction skid includes a compressor, a CO2 gas tank and a cooler. The evaporation gas main pipeline is connected to the compressor through a pipeline, the compressor is connected to the CO2 gas tank and the cooler through pipelines, the cooler is connected to the loading main pipeline, and the CO2 gas tank is connected to the CO2 fire extinguishing system.

[0017] In the above-mentioned solution of multiple liquid CO2 storage tanks sharing a liquid cargo system, further, a liquid cargo pump and a tank stripping pump are arranged at the overflow well.

[0018] The above-mentioned multiple liquid CO2 storage tanks share a liquid cargo system solution. Furthermore, the other end of the tank stripping main line is connected to the impurity receiving ship, and the impurities in the CO2 storage tanks are transported to the impurity receiving ship through the tank stripping main line.

[0019] The above-mentioned solution of multiple liquid CO2 storage tanks sharing a liquid cargo system further only has one loading system or unloading system.

[0020] In the above-mentioned solution of multiple liquid CO2 storage tanks sharing a liquid cargo system, further, the connecting pipelines and the isolation valves on the connecting pipelines are wrapped with an insulating layer on the outside.

[0021] The present invention provides a design scheme for a shared liquid cargo system of a highly economical CO2 storage tank, which reduces system configuration through system sharing, especially greatly reduces the number of liquid cargo pumps, and reduces the procurement cost of ship-related systems.

[0022] System sharing reduces system configuration, and the size design and selection of liquid CO2 storage tanks are more flexible, avoiding making a single storage tank very large due to system cost considerations, which increases installation difficulty and cost. After adopting the patent of this invention, the size of the storage tank can be reduced, the lifting and installation weight can be reduced, and thus the installation cost can be reduced.

[0023] By connecting the shared pipeline of the boil-off gas in the CO2 storage tank to the liquefaction treatment system, the liquefaction treatment system adopts a low-temperature and low-pressure treatment process to achieve the reliquefaction of the boil-off gas, and the liquefied CO2 is transported back to the storage tank again. The evaporation loss of liquid CO2 in the storage tank is reduced, and the economy of the ship is improved.

[0024] By adding a CO2 gas storage tank to store a portion of CO2 gas, it is used to adjust the problem that the reliquefaction air compressor cannot work smoothly when the evaporation gas is unstable.

[0025] The low-temperature and low-pressure reliquefaction method is adopted to deal with the liquefaction problem of the evaporated gas from the liquid CO2 storage tank, which fully utilizes the low-temperature cold energy of the liquid CO2, reduces the capacity of the compressor, reduces the energy consumption of the ship, and thus reduces the operating cost of the ship.

[0026] The liquid CO2 evaporated gas is fully utilized to realize the function of self-filling the gas cylinder of the ship's CO2 fire extinguishing system, which reduces the ship's CO2 fire extinguishing system's need for the outside world and improves the economy and safety of the ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the system solution of the present invention; Figure 2 This is a schematic diagram of the loading system solution of the present invention; Figure 3 This is a schematic diagram of the unloading system solution of the present invention; Figure 4 This is a schematic diagram of the tank stripping system of the present invention; Figure 5 This is a schematic diagram of the boil-off gas reliquefaction system of the present invention; Figure 6 This is a schematic diagram of the boil-off gas CO2 gas storage system of the present invention; Figure 7 This is a schematic diagram of the system for charging the gas cylinder of the CO2 fire extinguishing system of a ship with boil-off gas CO2 gas according to the present invention; Among them, 1-liquid CO2 storage tank, 2-connecting pipeline, 3-tank stripping branch pipeline, 4-evaporate gas branch pipeline, 5-CO2 low-temperature and low-pressure liquefaction skid, 6-unloading pipeline, 7-loading branch pipeline, 8~8a~8k-loading branch pipeline isolation valve, 9-unloading system isolation valve, 10~10a~10j-tank stripping system isolation valve, 11~11a~11s-evaporate gas pipeline isolation valve, 12-liquid cargo unloading pump, 13-compressor, 14-CO2 gas storage tank, 15-CO2 fire extinguishing system, 16-tank stripping pump, 17~17a~17f-connecting pipeline isolation valve, 18-cooler, 19-overflow well, 20-loading main pipeline, 21-tank stripping main pipeline, 22-evaporate gas main pipeline, 23-insulation layer. DETAILED DESCRIPTION

[0028] Multiple liquid CO2 storage tanks share a liquid cargo system, such as Figure 1 As shown, it includes multiple liquid CO2 storage tanks and a liquid cargo system. The liquid cargo system includes a loading system, an unloading system, a tank stripping system, a CO2 fire extinguishing system and a low-temperature and low-pressure reliquefaction skid. All system pipelines installed inside and outside the liquid CO2 storage tanks are installed inside and outside the liquid CO2 storage tanks according to the previous design and relevant specifications and standards.

[0029] The liquid cargo unloading pump is installed at the overflow well position in the No. 1 liquid tank and connected to the unloading pipeline 6. This embodiment takes the No. 3 liquid tank as an example.

[0030] Install the tank stripping pump 16 in the storage tank to the overflow well position of the liquid CO2 storage tank and connect it to the tank stripping branch pipeline 3 in the liquid CO2 storage tank.

[0031] The manufactured liquid CO2 storage tank 1 is installed on the corresponding ship according to the preliminary design plan and relevant specifications and standards.

[0032] The bottom connecting pipeline 2 of the liquid CO2 storage tank and the isolation valves 17a~17f of the bottom connecting pipeline of the liquid CO2 storage tank are installed at the corresponding positions according to the preliminary design plan and relevant specifications and standards. The bottoms of multiple liquid CO2 storage tanks are connected in series through the bottom connecting pipeline 2 and the connecting pipeline isolation valve, so that the bottoms of multiple liquid CO2 storage tanks are interconnected.

[0033] Install thermal insulation on the bottom connecting pipe 2 of the liquid CO2 storage tank and the connecting pipe isolation valves 17a~17f, and check the reliability after installation to ensure that the thermal insulation will not cause low-temperature leakage after installation.

[0034] Install the pipelines, isolation valves, low-temperature and low-pressure reliquefaction skid 5 of each system to the corresponding positions on the ship according to the preliminary design plan and relevant specifications and standards; Connect the air compressor output pipeline of the low-temperature and low-pressure reliquefaction skid 5 and the output pipeline of the CO2 gas storage tank to the ship's carbon dioxide fire extinguishing system pipeline.

[0035] After completing the above installation and connection work, the entire system needs to be debugged and inspected according to the design and relevant specifications and standards to ensure the safety and reliability of the system.

[0036] After completing the above inspection and testing work, the target ship can start the loading operation of low-temperature CO2.

[0037] like Figure 2As shown, the external cryogenic liquid CO2 transport ship is docked with the input port of the loading main pipeline on the loaded ship. There are two main operation modes for loading liquid CO2 in the three liquid CO2 storage tanks. One is that the liquid CO2 input from the outside can be directly loaded into the three liquid CO2 storage tanks through the loading main pipeline and the device branch pipeline. During loading, the loading branch pipeline isolation valves 8, 8a, 8b, 8c, 8f, 8j, 8j and 8i on the loading main pipeline and the loading branch pipeline can be opened according to the loading needs to realize the simultaneous loading of the three liquid storage tanks. Each tank can also be loaded separately, just open the pipeline isolation valve on each liquid tank separately. Another mode is to open the connecting pipeline isolation valves 17, 17a, 17b, 17c, 17d, 17e, and 17f on the bottom connecting pipeline 2 on the overflow well at the bottom of the liquid CO2 storage tank. In this way, as long as liquid CO2 is loaded into any liquid CO2 storage tank 1, it will be transferred to several other liquid CO2 storage tanks through the bottom connecting pipe 2. This solution can still meet the needs of loading liquid CO2 to a certain liquid storage tank when there is a problem with the loading branch pipe or isolation valve on a certain liquid storage tank.

[0038] like Figure 3 As shown, when the target ship needs to unload the liquid CO2 in the hydraulic CO2 storage tank to other ships or inject it into the storage site, a single tank unloading or multiple tanks unloading at the same time is required according to the operation mode. When a single tank is used for unloading, the No. 1 liquid CO2 storage tank is used as the main unloading tank. First, all the connecting pipeline isolation valves 17, 17a, 17b, 17c, 17d, 17e, and 17f on the bottom connecting pipeline 2 are closed, and the isolation valves 8, 8a, and 8c on the loading main pipeline are also closed. The unloading system isolation valve 9 and the loading system isolation valve 8b on the unloading pipeline 6 are opened, and the liquid cargo unloading pump 12 is started. The liquid cargo unloading pump 12 will then transfer the liquid CO2 in the No. 1 liquid CO2 storage tank through the unloading pipeline 6 and the unloading system isolation valve 8b. 9 and the loading main pipeline 7 and the loading system isolation valve 8b are unloaded to other ships or injected into the storage site; if the liquid CO2 in the No. 2 liquid CO2 storage tank also needs to be transported out at the same time, it is only necessary to open the connecting pipeline isolation valves 17, 17a, 17b on the bottom connecting pipeline 2, and the liquid CO2 in the No. 2 liquid CO2 storage tank will automatically flow through the bottom connecting pipe to the No. 1 liquid CO2 storage tank, and be discharged and unloaded to other ships or injected into the storage site through the liquid cargo unloading pump 12; the above scheme can also be used for unloading the No. 3 liquid CO2 storage tank.

[0039] like Figure 4As shown, after the liquid CO2 storage tank 1 is cleaned, when the dirty liquid in the tank needs to be discharged, the dirty liquid at the bottom of each tank needs to be discharged from the liquid CO2 storage tanks No. 1, 2, and 3 through the stripping pump 16 arranged in the storage tank through the stripping branch pipeline 3 and the stripping system isolation valves 10, 10a, 10b, 10c, 10d, 10e, 10h, 10g installed on the pipe, and the stripping system isolation valves 10j, 10f are opened and closed; the connecting pipeline isolation valves 17, 17a, 17b, 17c, 17d, 17e, 17f on the bottom connecting pipeline 6 of the three storage tanks can also be opened separately or all of them, so that the dirty liquid in the liquid CO2 storage tanks No. 2 and No. 3 will flow to the overflow well at the bottom of the liquid CO2 storage tank No. 1 through the bottom connecting pipeline 2, so that the stripping operation of the three tanks can be realized by only opening the stripping pump 16 in the liquid CO2 storage tank No. 1.

[0040] like Figure 5 As shown, when the liquid CO2 stored in the liquid CO2 storage tank 1 evaporates to produce gaseous CO2, when the gas pressure in the storage tank is too high, the evaporated gas will be collected from the branch pipeline of the evaporation gas circuit 4 connected to the storage tank 1 to the main pipeline, and then reach the air compressor 13 of the low-temperature and low-pressure reliquefaction skid 5 and the gas inlet boundary of the gas discharge column through the main pipeline. If the collected gas pressure and flow rate do not exceed the standard, the evaporated gas pipeline isolation valve 11i on the pipeline connected to the gas discharge column will be in a closed state, and the evaporated gas pipeline isolation valve 11j on the pipeline connected to the air compressor 13 on the low-temperature and low-pressure reliquefaction skid 5 will be opened. This part of the collected gas enters the compressor 13 for compression, and the compressed gas is compressed by The liquid CO2 enters the cooler 18 through the boil-off gas pipeline isolation valve 11o. In order to make full use of its own cold energy and reduce the high compression demand of the compressor 13, the stripping pump 16a in the liquid CO2 storage tank 1 is started at this time. The liquid CO2 in the No. 2 storage tank is passed through the stripping pipeline 3 by the stripping pump 16a, and enters the cooler 18 through the opened stripping system isolation valves 10h, 10c, and 10j to become the gas coolant after cooling the gas compressed from the compressor 13. The boil-off gas is liquefied from gas to liquid in the cooler by low temperature and low pressure. After the liquid CO2 comes out of the cooler, it is loaded into the storage tank again through the loading pipeline 7 and the opened loading branch pipeline isolation valves 8d, 8f, and 8j. Thus, the operation process of boil-off gas reliquefaction is completed.

[0041] like Figure 6As shown, because the evaporation amount of the evaporation gas in the liquid CO2 storage tank is in a fluctuating state, the flow rate and pressure of the evaporation gas discharged from the storage tank are constantly changing. The fluctuating evaporation gas has a great influence on the compression efficiency of the compressor 13. In order to reduce the problem of the fluctuation of the evaporation gas affecting the operation of the compressor 13, a CO2 gas storage tank is set on the low-temperature and low-pressure reliquefaction skid 5. Some CO2 gas is first stored in the gas cylinder. When the evaporation gas in the storage tank 1 is unstable, the CO2 gas storage tank 14 will release a part of the CO2 gas as needed to adjust the evaporation gas entering the compressor 13. The gas in the gas storage tank needs to be stored in advance by compressing the evaporation gas coming out of the liquid storage tank through the compressor 13. The specific operation process is that the evaporation gas from the liquid storage cylinder enters the compressor 13 and is compressed, and then is stored in the CO2 gas storage tank 14 through the evaporation gas pipeline through the opened evaporation gas pipeline isolation valves 11n, 11m, and 11L. The evaporation gas pipeline isolation valves 11o, 11q, 11k on the pipeline connected to the pipeline need to be in a closed state.

[0042] like Figure 7 As shown, according to regulatory requirements, ships need to be equipped with a CO2 system for fire extinguishing. The system is equipped with a CO2 cylinder 15, which stores CO2 gas. When a fire occurs, the gas in the CO2 cylinder will be released to the area where the fire occurs through a pipeline. When the CO2 gas in the cylinder 15 is emptied, an external gas source is required for filling. Since the product of the evaporation of liquid CO2 in the liquid CO2 storage tank 1 is CO2 gas, when the CO2 cylinder 15 needs to be filled with CO2 gas, the gas in the CO2 storage tank 14 can be released, and the gas will be combined with the gas evaporated from the liquid CO2 storage tank through the opened evaporation gas pipeline isolation valves 11L and 11k and then enter the compressor 13. After being increased by the compressor, it is transported to the CO2 storage tank 15 of the ship's CO2 fire extinguishing system through the evaporation gas pipeline through the opened evaporation gas pipeline isolation valves 11n and 11q for gas filling. Thereby, the ship's self-filling of the CO2 storage tank in the CO2 fire extinguishing system is realized.

Claims

1. A solution for multiple liquid CO2 storage tanks to share a liquid cargo system, characterized in that: There are a plurality of liquid CO2 storage tanks (1), and overflow wells (19) are arranged at the bottom of the plurality of liquid CO2 storage tanks. Adjacent overflow wells are interconnected via connecting pipelines (2). A plurality of connecting pipeline isolation valves are arranged on the connecting pipelines at the overflow wellheads. The plurality of connecting pipeline isolation valves control the flow directions of the liquid. A plurality of loading branch pipelines (7) extend from a loading main pipeline (20) and extend into each liquid CO2 storage tank respectively. The other end of the loading main pipeline is connected to a loading system or an unloading system. A liquid cargo unloading pump (12) is arranged in one of the liquid CO2 storage tanks, and the liquid cargo unloading pump is connected to the loading main pipeline via an unloading pipeline (6); A plurality of stripping branch pipes (3) extend from the CO2 stripping main pipe (21) and extend into each liquid CO2 storage tank respectively, and are connected to the stripping pumps (16) in each liquid CO2 storage tank; A boil-off gas branch pipeline (4) is provided on the top of each liquid CO2 storage tank. The boil-off gas branch pipeline is collected in the boil-off gas main pipeline (22), enters the CO2 low-temperature and low-pressure liquefaction skid (5) through the boil-off gas main pipeline, and after being processed by the CO2 low-temperature and low-pressure liquefaction skid, returns to each liquid CO2 storage tank through the loading branch pipeline; A plurality of tank stripping system isolation valves are arranged on the CO2 tank stripping main line, and the flow of liquid CO2 storage tanks during the tank stripping process is controlled by opening and closing the plurality of tank stripping system isolation valves.

2. A solution for multiple liquid CO2 storage tanks to share a liquid cargo system according to claim 1, characterized in that: The CO2 low-temperature and low-pressure liquefaction skid comprises a compressor (13), a CO2 gas storage tank (14) and a cooler (18); the evaporation gas main pipeline is connected to the compressor through a pipeline; the compressor is connected to the CO2 gas storage tank and the cooler through pipelines respectively; the cooler is connected to the loading main pipeline; and the CO2 gas storage tank is connected to the CO2 fire extinguishing system (15).

3. A solution for multiple liquid CO2 storage tanks sharing a liquid cargo system according to claim 1, characterized in that: Liquid cargo pumps and stripping pumps are installed at the overflow well.

4. A solution for multiple liquid CO2 storage tanks sharing a liquid cargo system according to claim 1, characterized in that: The other end of the stripping main line is connected to the impurity receiving ship, and the impurities in the CO2 storage tank are transported to the impurity receiving ship through the stripping main line.

5. According to claim 1, a solution for multiple liquid CO2 storage tanks to share a liquid cargo system is characterized in that: Only one loading system or unloading system is provided.

6. A solution for multiple liquid CO2 storage tanks sharing a liquid cargo system according to claim 1, characterized in that: The connecting pipeline and the isolation valve on the connecting pipeline are both wrapped with an insulating and heat-preserving layer (23) outside.

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