System and method for storing CO2 in cargo hold of semi-cooling and semi-pressing type LPG (Liquefied Petroleum Gas) ship

Abstract

The invention belongs to the technical field of ships, and provides a semi-cooling and semi-pressing type LPG ship cargo hold CO2 storage system and a semi-cooling and semi-pressing type LPG ship cargo hold CO2 storage method. The system comprises a CO2 tank box, a CO2 hydrate synthesis unit, a cargo hold valve, a compressor, a coil pipe inlet connector, a circulating pump, an LPG liquid cargo hold, a heat exchange coil pipe, a coil pipe outlet connector and a stop valve. According to the method, when the semi-cold and semi-pressure type LPG ship is in a no-load sailing state, CO2 captured by the ship is treated through a hydrate method, the CO2 is stored in the empty semi-cold and semi-pressure type LPG liquid cargo tanks of the ship, when the ship stops at a port, a land heat source is connected to heat the two LPG liquid cargo tanks, CO2 hydrate is decomposed to obtain CO2 gas and water, and the CO2 gas and the water are stored in the semi-cold and semi-pressure type LPG liquid cargo tanks. And then the gaseous CO2 is conveyed to the land for treatment. By means of the method, the CO2 liquefaction cost in the ship navigation process is reduced, the problem that the CO2 hydrate storage space is large is solved, and good economical efficiency and practicability are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of ship technology, and in particular relates to a semi-cold and semi-pressurized LPG ship cargo hold storing CO 2 Systems and methods. Background Art

[0002] With the continuous growth of international trade, the number of ships is increasing. At present, the power source of ships is still mainly dependent on fossil fuels, which makes the annual carbon emissions of the shipping industry very huge. The International Maritime Organization (IMO) has set a new regulation on ship CO2 emissions. 2 Emission requirements are becoming increasingly stringent, so there is a need to control the CO in ship exhaust 2 Capture and storage are carried out, and LPG ships are no exception.

[0003] CO 2 Capture and storage technology (CCS technology for short) is an important technical means to reduce emissions from ships. 2 After being captured and separated, it is stored on board the ship to reduce CO 2 The storage volume and ease of loading and unloading are usually stored in liquid form in CO 2 Tank container (a kind of container that is easy to load and unload and can realize CO 2 The working pressure of the low-temperature tank for continuous storage is between 0.7MPa and 2MPa, and the working temperature is between -20℃ and -50℃. An LPG ship can capture about 30t to 60t of gaseous CO in one day. 2 , for such a huge CO 2 Liquefaction (at a pressure of 0.7 MPa to 1.5 MPa and a liquefaction temperature of -30°C to -50°C) requires a large amount of power consumption by the refrigeration system and generates a high level of CO 2 Liquefaction costs, in addition, are based on liquid CO 2 The storage capacity is large, which will require a large number of expensive CO 2 Tank storage of liquefied CO 2 Therefore, liquefaction is used to store the captured CO 2 , not only will it generate large power consumption, but it will also cause excessive CO 2 Tank containers require a large amount of capital investment, resulting in high economic costs, while also occupying a large amount of space resources on the ship.

[0004] CO 2 In addition to the above-mentioned liquefaction storage method, it can also be stored in the form of hydrates. If the CO captured by the ship is 2 Hydrate treatment is used, and every 1m 3 CO 2 Hydrate can store 164m3 CO 2 . And CO 2 Hydrate formation conditions are mild. At a temperature of 0℃ to 10℃, only 1.24MPa to 4.3MPa of pressure is needed to generate a large amount of CO 2 Hydrates have lower requirements and lower power consumption than liquefaction methods (pressure is 0.7MPa to 1.5MPa, liquefaction temperature is -30℃ to -50℃), and are an ideal CO 2 Storage method, but storing CO in the form of hydrates 2 The most prominent drawback is: the generated CO 2 The volume occupied by hydrates is relatively small compared to the volume of liquid CO obtained by liquefaction. 2 The volume is even larger.

[0005] After the fully loaded semi-refrigerated and semi-pressurized LPG ship arrives at the destination port and completes unloading, the ship's cargo hold sails empty during the return journey, and the ship's cargo hold has no carrying value. Usually, the design pressure of the semi-refrigerated and semi-pressurized LPG liquid cargo tank does not exceed 2MPa, and the design temperature is about -48℃. 2 Hydrates require a lot of space to store, and LPG and CO 2 The temperature and pressure conditions of hydrate storage are similar, so the empty semi-refrigerated and semi-pressurized LPG cargo tank can just provide CO 2 The storage of hydrates provides space. 2 It is stored in the empty LPG cargo tank in the form of hydrates, which can not only make full use of the cargo tank space when the LPG ship is sailing empty, but also reduce the impact on CO 2 Costs of liquefaction and storage.

[0006] Based on the above problems, a semi-refrigerated and semi-pressurized LPG cargo tank storage CO 2 System and method for converting CO2 emitted by the ship's main engine into 2 The LPG is stored in a semi-refrigerated and semi-pressurized LPG cargo tank in the form of hydrates. When the ship docks at the port, CO 2 This method will greatly reduce the storage of CO2 on ships. 2 cost and improve the economy of ships. Summary of the invention

[0007] The first object of the present invention is to propose a semi-refrigerated and semi-pressurized LPG cargo tank storage CO 2 system, the system comprising: CO 2 Liquefaction system, CO 2 Hydrate synthesis system and unloading system.

[0008] Among them, CO2 The liquefaction system includes: CO 2 Capture unit, CO 2 Liquefaction unit, CO 2 Tank container.

[0009] CO 2 The hydrate synthesis system includes: CO 2 Capture unit, CO 2 Hydrate synthesis unit, cargo tank valve, LPG liquid cargo tank.

[0010] The unloading system includes: compressor, coil inlet joint, circulation pump, LPG liquid cargo tank, heat exchange coil, coil outlet joint and stop valve.

[0011] In CO 2 In the liquefaction system, the ship main engine is connected to the CO 2 The capture unit is connected; the CO 2 The capture unit is connected to the CO 2 Liquefaction unit, CO 2 Tank containers are connected.

[0012] In CO 2 In the hydrate synthesis system, the CO 2 The capture unit is connected to the CO 2 The hydrate synthesis unit, cargo tank valve and LPG liquid cargo tank are connected.

[0013] In the unloading system, the top of the LPG liquid cargo tank is connected to the compressor through a pipeline; the bottom is connected to the stop valve through a pipeline; a heat exchange coil is provided in the LPG liquid cargo tank, and a coil inlet joint and a coil outlet joint are respectively provided at the inlet and the outlet, which can be connected to a land heating source and form a circulation pipeline through a circulation pump.

[0014] The second object of the present invention is to store CO in the semi-cold and semi-pressurized LPG cargo hold. 2 A semi-refrigerated and semi-pressurized LPG cargo tank storage system is proposed. 2 The purpose of this method is to reduce the CO2 emitted from the exhaust gas of a semi-refrigerated and semi-pressurized LPG ship when it is sailing without load. 2 Stored as hydrate in empty LPG cargo tanks.

[0015] When a ship is fully loaded, the exhaust gas emitted by the ship's main engine enters the CO 2 Capture unit, CO in tail gas 2 CO 2 The capture unit captures and separates the remaining gas, and the remaining gas is discharged into the outside atmosphere. 2 Enter CO 2 Liquefaction unit, CO2 The liquefaction unit captures CO 2 Liquefaction treatment to form liquid CO 2 Inflow CO 2 When a ship docks at a port, a crane is used to move CO 2 The tank container is lifted to land for processing.

[0016] When the ship arrives at the port and unloads LPG, the ship sails empty and the exhaust gas emitted by the ship's main engine enters the CO 2 Capture unit, CO in tail gas 2 CO 2 The capture unit captures and separates the remaining gas, and the remaining gas is discharged into the outside atmosphere. 2 Enter CO 2 Hydrate synthesis unit produces CO 2 hydrate, and open the cargo tank valve to allow CO 2 Hydrate is stored in two empty semi-refrigerated semi-pressurized LPG cargo tanks. When the ship is unloaded and docked at the port, the coil inlet and outlet joints are connected to the heating source on land, so that the higher temperature fluid flows through the heat exchange coil to heat the two LPG cargo tanks, and a circulation pipeline is formed through the circulation pump. 2 Hydrate decomposes to produce CO 2 Gas and water, CO 2 The gas is transported to land for processing under the action of the compressor; the water is discharged through the pipeline where the stop valve is located.

[0017] Beneficial effects of the present invention:

[0018] 1. The present invention uses the hydrate method to capture CO2 from a semi-cold and semi-pressure LPG ship when it is sailing empty. 2 Compared with the liquefaction method, the power consumption is lower, and the generated hydrate is stored in the empty LPG cargo tank, which solves the problem of CO 2 The problem with hydrates is that they require a lot of storage space.

[0019] 2. Compared with the traditional CO 2 The liquefied storage method has lower power consumption and can store CO2 when the ship is unloaded. 2 Stored in LPG cargo tanks in the form of hydrates, eliminating the need for CO 2 Tank container reduces CO 2 storage cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a system diagram of the present invention;

[0021] In the attached figure: 1.CO 2Tank container; 2.CO 2 Hydrate synthesis unit; 3. Cargo tank valve; 4. Compressor; 5. Coil inlet connector; 6. Circulation pump; 7. LPG liquid cargo tank; 8. Heat exchange coil; 9. Coil outlet connector; 10. Stop valve. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] A semi-refrigerated and semi-pressurized LPG cargo tank storage CO 2 System, such as Figure 1 As shown, the system includes: CO 2 Liquefaction system, CO 2 Hydrate synthesis system and unloading system.

[0024] Among them, CO 2 The liquefaction system includes: CO 2 Capture unit, CO 2 Liquefaction unit, CO 2 Tank container 1.

[0025] CO 2 The hydrate synthesis system includes: CO 2 Capture unit, CO 2 Hydrate synthesis unit 2, cargo tank valve 3, LPG liquid cargo tank 7.

[0026] The unloading system includes: a compressor 4, a coil inlet connector 5, a circulation pump 6, an LPG liquid cargo tank 7, a heat exchange coil 8, a coil outlet connector 9, and a stop valve 10.

[0027] In CO 2 In the liquefaction system, the ship's main engine is connected to the CO 2 The capture unit is connected; the CO 2 The capture unit is connected to the CO 2 Liquefaction unit, CO 2 The tank container 1 is connected. 2 Tank 1 is a low-temperature tank (working pressure between 0.7MPa and 2MPa, working temperature between -20℃ and -50℃) that can achieve CO 2 Continuous storage, when a CO 2 When tank 1 is full, new CO can be replaced according to actual needs. 2 Tank container 1.

[0028] In CO 2 In the hydrate synthesis system, the CO 2 The capture unit is connected to the CO 2The hydrate synthesis unit 2, the cargo tank valve 3, and the LPG liquid cargo tank 7 are connected. 2 Hydrate synthesis unit 2 is composed of gaseous CO 2 Reacts with water to generate CO at a certain temperature and pressure 2 The LPG liquid cargo tank 7 is a semi-refrigerated and semi-pressure liquid cargo tank, and the number of the LPG liquid cargo tanks can be increased or decreased according to the actual situation. In the present invention, two semi-refrigerated and semi-pressure LPG liquid cargo tanks 7 are taken as an example.

[0029] In the unloading system, the top of the LPG cargo tank 7 is connected to the compressor 4 through a pipeline; the bottom is connected to the stop valve 10 through a pipeline; a heat exchange coil 8 is provided in the LPG cargo tank 7, and a coil inlet joint 5 and a coil outlet joint 9 are provided at the inlet and outlet respectively, which can be connected to a land heating source and form a circulation pipeline through a circulation pump 6. The compressor 4 is a gas compressor, which converts gaseous CO 2 transported to land.

[0030] The present invention is based on the above-mentioned semi-cold and semi-pressure LPG ship cargo tank storage CO 2 A semi-refrigerated and semi-pressurized LPG cargo tank storage system was proposed. 2 The purpose of this method is to reduce the CO2 emitted from the exhaust gas of a semi-refrigerated and semi-pressurized LPG ship when it is sailing without load. 2 The LPG is stored in the empty LPG cargo tank 7 in the form of hydrates. The specific method is as follows:

[0031] When a ship is fully loaded, the exhaust gas emitted by the ship's main engine enters the CO 2 Capture unit, CO in tail gas 2 CO 2 The capture unit captures and separates the remaining gas, and the remaining gas is discharged into the outside atmosphere. 2 Enter CO 2 Liquefaction unit, CO 2 The liquefaction unit captures CO 2 Liquefaction treatment to form liquid CO 2 Inflow CO 2 In tank container 1, when the ship docks at the port, the CO 2 Tank container 1 is lifted to land for handling.

[0032] When the ship arrives at the port and unloads LPG, the ship sails empty and the exhaust gas emitted by the ship's main engine enters the CO 2 Capture unit, CO in tail gas 2 CO 2 The capture unit captures and separates the remaining gas, and the remaining gas is discharged into the outside atmosphere. 2 Enter CO 2Hydrate synthesis unit 2 produces CO 2 hydrate, and open cargo tank valve 3 to allow CO 2 The hydrate enters two empty semi-cold and semi-pressurized LPG cargo tanks 7 for storage. When the ship is docked at the port, the coil inlet joint 5 and the coil outlet joint 9 are connected to the heating source on land, so that the higher temperature fluid flows through the heat exchange coil 8 to heat the two LPG cargo tanks 7, and the circulation is formed through the action of the circulation pump 6. The CO in the LPG cargo tank 7 2 Hydrate decomposes to produce CO 2 Gas and water. CO 2 The gas is transported to land for processing under the action of the compressor 4; the water is discharged through the pipeline where the stop valve 10 is located.

[0033] Ships generate a large amount of CO during navigation. 2 If these CO 2 After capture, all the gas is liquefied, and the refrigeration system needs to generate a lot of power to achieve CO 2 The conditions required for liquefaction (gas pressure of 0.7MPa to 1.5MPa, liquefaction temperature of -30°C to -50°C), and the present invention uses the hydrate method to treat CO captured by the ship when the LPG ship is sailing empty. 2 , compared with the traditional CO 2 Compared with the liquefaction method, the hydrate method requires a higher operating temperature, so it generates lower power consumption. In addition, as the main means of transporting liquefied petroleum gas, after the LPG ship has completed the unloading of cargo, the LPG liquid cargo tank 7 sails empty, and the ship's cargo tank has no carrying value. At the same time, CO 2 Hydrate as an efficient CO 2 Storage form, per 1m 3 CO 2 Hydrates can capture 164m 3 CO 2 However, an LPG ship can generate 93m 3 ~185m 3 CO 2 Hydrates are produced, so a large amount of ship space is required for storage. The present invention makes full use of the empty semi-refrigerated and semi-pressurized LPG cargo tank 7 when the LPG ship is sailing empty. The conventional LPG cargo tank can hold tens of thousands of cubic meters of LPG, which is a great advantage for CO 2 Hydrate storage provides ample space, which not only solves the problem of CO 2 Hydrates require a lot of storage space and make full use of the cargo hold space when the ship is sailing empty.

[0034] In addition, ships usually use CO 2 Tank 1 pairs of CO2 captured and liquefied during voyage2 However, due to the long time ships spend at sea, the captured and liquefied CO 2 For example, a single trip from Qingdao Port to Iran by LPG ship usually takes about 20 days. 2 The density is 1101kg / m 3 , then the CO2 captured and liquefied in a single trip of the ship is 2 About 540m 3 ~1080m 3 , and a CO 2 Tank container 1 can usually only hold about 40m 3 Liquid CO 2 Therefore, a single trip of the ship requires approximately 30 CO 2 Tank 1 to store liquefied CO 2 It can be seen that the traditional liquefaction method for ships requires CO 2 Tank Container 1 has a large number of tank containers and due to CO 2 Tank 1 is expensive, so ships use traditional liquefaction to store CO 2 The cost is high. In the present invention, when the ship is sailing without load, the captured CO 2 In CO 2 Hydrate synthesis unit 2 converts into CO 2 hydrate, and CO 2 Hydrate is stored in LPG cargo tank 7, eliminating the need for CO 2 Tank 1, reducing CO 2 storage cost.

[0035] Furthermore, when the ship is docked at the port, the coil inlet connector 5 and the coil outlet connector 9 are connected to the heating source on land. The higher temperature fluid flows through the heat exchange coil 8 to heat the two LPG cargo tanks 7. 2 The storage temperature of hydrate is 0℃~10℃, so only a small amount of heat is needed to make the temperature in the cargo tank reach above 10℃. At this time, the land heat source can generate less energy consumption to make CO 2 Hydrate decomposes to obtain CO 2 gas, then CO 2 The gas is transported to land for processing. Compared with ships, land has sufficient space and more complete CO 2 Liquefaction systems and various treatment methods for CO 2 The cost of treatment is much lower than that of CO 2 Therefore, the present invention has good economy and practicability.

[0036] Furthermore, in order to enable the semi-refrigerated and semi-pressurized LPG cargo tank 7 to stably store CO 2 Hydrates can be used to appropriately thicken the bulkheads at the beginning of ship construction.

[0037] The above is only a preferred embodiment of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A semi-refrigerated and semi-pressurized LPG ship cargo hold CO2 storage system, characterized by: The system comprises a CO2 tank container (1), a CO2 hydrate synthesis unit (2), a cargo tank valve (3), a compressor (4), a coil inlet joint (5), a circulation pump (6), an LPG liquid cargo tank (7), a heat exchange coil (8), a coil outlet joint (9), and a stop valve (10). The ship's main engine is connected to the CO2 capture unit via a pipeline, and the CO2 capture unit is connected to the CO2 liquefaction unit and the CO2 tank (1) in turn. The CO2 capture unit is connected to the CO2 hydrate synthesis unit (2), the cargo tank valve (3), and the LPG liquid cargo tank (7) in sequence. The top of the LPG liquid cargo tank (7) is connected to a compressor (4) via a pipeline; the bottom is connected to a stop valve (10) via a pipeline; a heat exchange coil (8) is provided in the LPG liquid cargo tank (7); a coil inlet joint (5) and a coil outlet joint (9) are provided at the inlet and outlet of the heat exchange coil (8), respectively, and can be connected to a land heating source, and a circulation pipeline is formed through a circulation pump (6).

2. A method for storing CO2 in a semi-cold and semi-pressurized LPG ship cargo hold, using the system of claim 1, characterized in that: When the ship arrives at the port and completes the unloading of LPG, the ship sails empty, and the exhaust gas emitted by the ship's main engine enters the CO2 capture unit, where the CO2 in the exhaust gas is captured and separated. The captured CO2 enters the CO2 hydrate synthesis unit (2) to generate CO2 hydrate, and the CO2 hydrate enters two empty semi-refrigerated and semi-pressure LPG liquid cargo tanks (7) for storage.

3. A method for storing CO2 in a semi-cold and semi-pressurized LPG ship cargo hold, using the system of claim 1, characterized in that: When the ship is sailing empty and docking at the port, the two LPG liquid cargo tanks (7) are heated to make the temperature inside the liquid cargo tanks reach above 10°C, and the CO2 hydrate in the LPG liquid cargo tanks (7) is decomposed to obtain CO2 gas and water. The CO2 gas is transported to land for treatment under the action of the compressor (4); and the water is discharged through the pipeline where the stop valve (10) is located.

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