A co2 capture storage system for a propane carrier

Abstract

The application provides a CO2 storage system for a propane carrier, which comprises a cargo hold and a common CO2 tank. The CO2 tank is ingeniously placed in the cargo hold filled with liquid propane, so that the common CO2 tank is immersed in the propane, and the refrigerating unit of the cargo hold is used for centralized refrigeration of the propane and the common CO2 tank. The refrigerating unit for refrigerating the common CO2 tank is not separately arranged on the ship, so that the equipment cost and operation cost generated by refrigeration for the common CO2 tank are saved, the common pressure tank instead of the C-type tank is adopted, the storage cost of the liquid CO2 captured in the process of ship sailing is greatly reduced, meanwhile, a more reasonable storage place for the CO2 tank is found, and the technical problem of liquid CO2 storage on the ship is solved. Therefore, under the trend of green low-carbon and energy saving and emission reduction of the ship, the application has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ships, and particularly relates to a CO2 capture and storage system for a propane carrier. BACKGROUND

[0002] At present, fossil fuels are still the main energy material, and the greenhouse gases such as CO2 generated by the combustion of fossil fuels aggravate the greenhouse effect, which in turn leads to serious global warming. Therefore, according to the carbon emission requirements of the International Maritime Organization, the carbon emission amount needs to be controlled, and thus the CO2 in the exhaust gas of a ship needs to be captured and stored.

[0003] Propane, as an organic compound, is the main component of liquefied petroleum gas. In addition, propane is also widely used as a refrigerant in oil refining, chemical industry and natural gas processing operations. At present, full cold propane carriers are usually used to transport liquid propane. During the transportation process, the temperature in the cargo hold of the propane carrier must be maintained at about -42℃ to ensure that the propane is in a liquid state. Therefore, a refrigeration unit is usually provided on the propane carrier to continuously refrigerate the cargo hold and maintain the ideal temperature of the propane in the cargo hold at about -42℃.

[0004] The propane carrier also uses fossil fuels such as marine fuel for the main engine. The exhaust gas generated by the combustion of fossil fuels contains a large amount of CO2 and other greenhouse gases. Therefore, the CO2 in the exhaust gas needs to be captured and liquefied for storage. In order to facilitate the loading, unloading and transportation of CO2 on the ship, CO2 is usually stored in a liquid state. There are two ways to keep CO2 in a liquid state: full pressure and semi-cold semi-pressure. The full pressure type uses high pressure to liquefy CO2, which requires a very high pressure for the storage tank. The semi-cold semi-pressure storage method requires relatively low temperature and pressure for the storage tank. If the storage volume is large, it has more advantages. Therefore, the large-capacity CO2 storage on the ship usually adopts the semi-cold semi-pressure method (the pressure of the storage tank is 1.0MPa-1.5MPa, and the temperature is -36.61℃-25.74℃) to keep it in a liquid state for storage. At present, the most common container for storing liquid CO2 is a C-type tank. The C-type tank is a cylindrical body, and a thermal insulation layer is provided on the surface of the tank. Even if a thermal insulation layer is provided, there is still a large temperature difference between the C-type tank and the surrounding environment, and heat exchange occurs between the C-type tank and the outside environment. After a period of time, CO2 evaporation gas (BOG for short) is inevitably generated. Therefore, the method of storing CO2 by using a C-type tank still needs a refrigeration unit to refrigerate it to avoid the generation of BOG. However, the refrigeration unit needs to be continuously operated, which consumes a large amount of power of the ship power grid. In addition, the number of CO2 storage tanks may be large, which greatly increases the cost of CO2 storage. Moreover, the C-type tank with a thermal insulation layer is expensive, and therefore the cost of CO2 storage is very high.

[0005] In addition, the current propane carrier cargo capacity is mostly 80000m 3 ~100000m 3 When the propane carrier transports the cargo, the ship main engine will produce a large amount of exhaust gas, and the ship exhaust gas contains a large amount of CO2, wherein about 3.2 tons of CO2 will be produced for each ton of marine fuel. Taking the propane carrier with a cargo capacity of 80000m 3 as an example, the ship fuel consumption is about 40 tons per day, for example, the single trip of the propane carrier from Qingdao port to Iran usually takes about 20 days, and the density of liquid CO2 is known to be 1101kg / m 3 , assuming that the capture rate of CO2 in the ship exhaust gas is 75%, the liquid CO2 captured by the ship in a single trip is about 1743.87m 3 Therefore, a large number of C-type tanks need to be arranged on the ship to store CO2, in addition, because the C-type tank is a cylindrical body, there are many gap spaces between the CO2 storage tank and the ship body or between the CO2 storage tanks, so that the actual space occupied by the C-type tank on the ship is much larger than the effective space of 1743.87m 3 (about 3000m 3 ~3500m 3 of space is required). Therefore, the arrangement of the C-type tank for storing CO2 on the propane carrier is difficult.

[0006] Therefore, if a propane carrier CO2 capture and storage system can be proposed, the ordinary CO2 storage tank is placed in the cargo hold containing liquid propane, and the CO2 storage tank is placed in the ideal low temperature environment of about -42℃, not only provides a relatively ideal storage space for the CO2 storage tank, but also uses the low temperature of the liquid propane to provide an ideal low temperature environment for the liquid CO2, and does not need to set up a separate refrigeration unit to refrigerate the CO2 storage tank, avoiding the generation of BOG, in addition, using the relatively low-cost ordinary pressure tank to replace the C-type tank, solving the problem of high cost of CO2 storage by using C-type tank, greatly reducing the cost of CO2 storage, and improving the economy of the ship. SUMMARY

[0007] The present application aims at the above-mentioned problems, and provides a CO2 storage system for a propane carrier. The ordinary CO2 tank is stored together with the liquid propane in the cargo hold of the propane carrier, so that both are in the same working condition and share the same refrigeration unit, the low temperature of the liquid propane provides an ideal low-temperature storage environment for the CO2 tank, and the CO2 is kept in liquid state, and the liquid CO2 can be stored without BOG, meanwhile, the ordinary pressure tank is used to replace the C-type tank to store the CO2, which can greatly reduce the CO2 storage cost. In addition, the CO2 tank is stored together with the liquid propane, which can solve the storage space problem and reasonably and fully utilize the cargo hold space of the propane carrier.

[0008] The present application provides a CO2 storage system for a propane carrier, which comprises a cargo hold and an ordinary CO2 tank.

[0009] The ship main engine is connected with the CO2 capture unit through a pipeline, one side of the CO2 capture unit is connected with the atmosphere through a pipeline, the other side of the CO2 capture unit is connected with the CO2 liquefaction unit through a pipeline, and the CO2 liquefaction unit is connected with the ordinary CO2 tank through a pipeline.

[0010] The cargo hold is filled with liquid propane, the surface of the cargo hold is provided with a heat preservation layer, and the cargo hold is provided with a refrigeration unit. The ordinary CO2 tank is an ordinary pressure tank without a heat preservation layer, the working pressure is greater than or equal to 0.83 MPa, and the working temperature is-42℃. A plurality of ordinary CO2 tanks are arranged on the ship, and the number is determined according to the amount of CO2 captured during the voyage. The ordinary CO2 tanks are placed in the cargo hold, and all the ordinary CO2 tanks are placed in the same cargo hold.

[0011] During the voyage of the propane carrier, the exhaust gas generated by the ship main engine enters the CO2 capture unit, the CO2 capture unit separates the CO2 from other gases in the exhaust gas of the ship, the other gases are directly discharged into the atmosphere, and the CO2 is collected and transported to the CO2 liquefaction unit through a pipeline, the CO2 liquefaction unit performs liquefaction treatment on the captured CO2, and the liquefied CO2 is transported to the ordinary CO2 tank through a pipeline for storage.

[0012] The storage of the liquid CO2 captured during the voyage of the ship has the following two working conditions:

[0013] When the propane carrier is fully loaded and sails, the refrigeration unit of the cargo hold of the ship performs refrigeration on the cargo hold, so that the cargo hold and the liquid propane are at an ideal temperature of about-42℃, and then the low temperature (-42℃) of the liquid propane makes the ordinary CO2 tank in an ideal low-temperature environment, so that the ordinary CO2 tank does not generate heat penetration with the surrounding environment, and ensures that the CO2 is always in liquid state to avoid the generation of BOG.

[0014] When the propane carrier is sailing empty, a part of liquid propane is still remained in the cargo hold, the low temperature (-42℃) of the remained liquid propane and the refrigeration unit in the cargo hold work together to make the ordinary CO2 tank in an ideal low temperature environment, so that the ordinary CO2 tank does not generate heat penetration with the surrounding environment, ensures that CO2 is always in liquid state, and avoids the generation of BOG.

[0015] Further, the ordinary CO2 tank in the present application is placed in the cargo hold close to the ship's center, to ensure the center of gravity distribution of the ship when it is empty, to avoid serious longitudinal inclination of the ship, and to improve the stability of the ship.

[0016] The beneficial effects of the present application are:

[0017] 1. The present application ingeniously places the CO2 tank in the cargo hold containing liquid propane, and uses the refrigeration unit in the cargo hold to concentrate refrigeration on the propane and CO2 tank, compared with the method of refrigerating the CO2 tank alone, the power consumption of the refrigeration unit is reduced, and the refrigeration cost of the ordinary CO2 tank is greatly reduced.

[0018] 2. The present application ingeniously places the ordinary CO2 tank in the cargo hold containing liquid propane, and uses the ordinary pressure tank to replace the high-cost C-type tank to store liquid CO2, the ordinary CO2 tank does not need an insulation layer, which greatly reduces the cost of the CO2 storage container.

[0019] 3. The present application ingeniously places the ordinary CO2 tank in the cargo hold containing liquid propane, which solves the problem of storage space for captured CO2 during the sailing process of the propane carrier. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view of the ordinary CO2 tank placed in the cargo hold;

[0021] Figure 2 is a system flow chart of the ship's exhaust gas carbon capture and liquefaction;

[0022] Figure 3 is a schematic view of the transverse section;

[0023] Figure 4 is a cross-sectional view of A-A;

[0024] Figure 5 is a schematic view of the transverse section of the cargo hold where the ordinary CO2 tank is located when the ship is empty;

[0025] Figure 6 is a schematic view of the transverse section of the cargo hold where the ordinary CO2 tank is located when the ship is empty.

[0026] In the drawings: 1. cargo hold; 2. ordinary CO2 tank. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples.

[0028] A CO2 storage system for a propane carrier, as shown in Figure 1 and Figure 2 , comprises a cargo hold 1 and a common CO2 tank 2.

[0029] The cargo hold 1 is filled with liquid propane, and a thermal insulation layer is arranged on the surface of the cargo hold 1. The cargo hold 1 is provided with a refrigeration unit.

[0030] The common CO2 tank 2 is a common pressure tank without a thermal insulation layer, and has a working pressure greater than or equal to 0.83 MPa and a working temperature of -42℃. The common CO2 tank 2 is provided in multiple groups on the propane carrier, and the number thereof is determined according to the actual situation (i.e. the amount of CO2 captured during the navigation of the carrier). The common CO2 tank 2 is centrally arranged inside the cargo hold 1 filled with liquid propane, as shown in Figure 3 .

[0031] As shown in Figure 2 , it is a system flow chart of ship exhaust gas carbon capture and liquefaction. The ship main engine is connected with a CO2 capture unit through a pipeline. One side of the CO2 capture unit is connected with the atmosphere through a pipeline. The other side of the CO2 capture unit is connected with a CO2 liquefaction unit through a pipeline. The CO2 liquefaction unit is connected with the common CO2 tank 2 through a pipeline. The CO2 capture unit separates CO2 from other gases in the flue gas. The CO2 liquefaction unit liquefies the captured CO2.

[0032] Currently, four cargo holds are usually arranged along the length direction of the mainstream propane carrier, as shown in Figure 1 and Figure 4 . The four cargo holds 1 along the bow to stern direction are sequentially a No. 1 cargo hold, a No. 2 cargo hold, a No. 3 cargo hold and a No. 4 cargo hold.

[0033] In the present application, the common CO2 tank 2 should be centrally arranged in the No. 2 cargo hold or the No. 3 cargo hold to ensure the distribution of the center of gravity of the carrier when it is empty, avoid serious longitudinal inclination of the carrier and improve the stability of the carrier.

[0034] The present application is based on a propane carrier with a cargo carrying capacity of 82000 m 3 (about 47000 tons when the carrier is fully loaded, calculated according to the density of liquid propane of 580 kg / m 3 ), and the common CO2 tank 2 is centrally arranged in the No. 3 cargo hold.

[0035] During the navigation of the propane carrier, if the CO2 captured by the CO2 capture unit is less than the capacity of the common CO2 tank 2,Figure 2 As shown in the figure, the exhaust gas generated by the main engine of the ship enters the CO2 capture unit, the CO2 capture unit separates the CO2 in the ship exhaust gas from other gases, the other gases are directly discharged into the atmosphere, and the CO2 is collected and transported to the CO2 liquefaction unit through the pipeline, the CO2 liquefaction unit performs liquefaction treatment on the captured CO2, and the liquefied CO2 is transported to the ordinary CO2 storage tank 2 through the pipeline.

[0036] The storage of the captured liquid CO2 on the ship during the ship's voyage has the following two working conditions:

[0037] When the propane transport ship is full of load, the refrigeration unit of the ship's cargo hold carries out refrigeration to the cargo hold 1, so that the cargo hold 1 and the liquid propane are at an ideal temperature of about -42°C. The ordinary CO2 storage tank 2 in this embodiment is concentrated and stored in the No. 3 cargo hold containing liquid propane, so that the CO2 storage tank 2 is immersed in the liquid propane, and the low temperature (-42°C) of the propane provides an ideal low temperature environment for the ordinary CO2 storage tank 2, so that the ordinary CO2 storage tank 2 does not generate permeation heat with the surrounding environment, keeps the CO2 always in liquid state, and avoids the generation of BOG.

[0038] When the propane transport ship is empty, according to the ship navigation and cargo transportation common sense, the cargo hold 1 of this 82000m 3 propane transport ship still has about 350 tons of liquid propane, as shown in Figure 5 and Figure 6 , so the propane transport ship also needs a low temperature environment of about -42°C when it is empty, so the refrigeration unit is still needed to refrigerate the cargo hold 1. The ordinary CO2 storage tank 2 in this embodiment is placed in the No. 3 cargo hold containing part of the liquid propane, and the low temperature (-42°C) of the part of the liquid propane remaining in the No. 3 cargo hold and the refrigeration unit of the cargo hold 1 work together to provide an ideal low temperature environment for the ordinary CO2 storage tank 2, so that the ordinary CO2 storage tank 2 does not generate permeation heat with the surrounding environment, keeps the CO2 always in liquid state, and avoids the generation of BOG.

[0039] Further, when the propane transport ship returns to the loading port to refill propane, the temperature of the cargo hold 1 will slowly recover to normal temperature after a long voyage, and if the propane is directly refilled at this time, it will cause a sharp drop in the temperature of the cargo hold 1 and generate a large thermal stress, therefore, the present application leaves 350 tons of propane in the cargo hold 1 when the ship is empty, and relies on the cold energy of the propane to keep the cargo hold 1 at a relatively low temperature, so as to avoid a large thermal stress when refilling the propane.

[0040] A large amount of exhaust gas is generated during the navigation of a ship, and the exhaust gas contains a large amount of CO2, so a large number of ordinary CO2 storage tanks 2 need to be arranged on the ship, if a refrigerating unit is arranged for each of the ordinary CO2 storage tanks 2 to refrigerate the ordinary CO2 storage tank 2, not only a large amount of equipment cost is generated, but also a large amount of power of the power grid of the ship is consumed due to the continuous operation of the refrigerating unit, and the cost of CO2 storage is greatly increased. The ordinary CO2 storage tank 2 is arranged in the cargo hold 1 filled with liquid propane in the application, and the refrigerating unit of the cargo hold 1 is used to refrigerate the liquid propane and the ordinary CO2 storage tank 2, compared with the method of refrigerating the CO2 storage tank 2 alone, the equipment cost and operation cost of the refrigerating unit are saved, and in addition, due to the existence of the scale effect, the refrigeration cost of the ordinary CO2 storage tank 2 is greatly reduced.

[0041] The scale effect refers to that during the navigation of the ship, the refrigerating unit of the cargo hold 1 needs to be continuously operated to ensure that the cargo hold 1 and the liquid propane are at an ideal temperature of about -42 DEG C. The ordinary CO2 storage tank 2 is arranged in the cargo hold 1 in the application, and the refrigerating unit of the cargo hold 1 is used to refrigerate the liquid propane and the ordinary CO2 storage tank 2, although the power consumption of the refrigerating unit of the cargo hold 1 is increased to a certain extent, compared with the total power consumption generated by arranging two sets of refrigerating systems (the refrigerating system of the cargo hold 1 and the refrigerating system of the ordinary CO2 storage tank 2) on the ship, the total power consumption is greatly reduced, and the refrigeration cost of the ordinary CO2 storage tank 2 is greatly reduced.

[0042] In addition, the ordinary pressure storage tank is used to replace the high-cost C-type tank to store the liquid CO2 in the application, and the surface of the storage tank does not need to be provided with a heat preservation layer, so the cost of the CO2 storage container is greatly reduced. In addition, the saturated pressure of the liquid CO2 is 0.83 MPa at a low temperature of -42 DEG C, so the working pressure of the ordinary CO2 storage tank 2 in the application only needs to be greater than or equal to 0.83 MPa to achieve the storage condition of the liquid CO2, if the working pressure of the CO2 storage tank 2 is less than 0.83 MPa, BOG is generated. Actually, the CO2 storage tank 2 in the application is equivalent to a full-pressure storage tank, but compared with the traditional full-pressure storage tank, the high pressure of 7 MPa needs to be borne by the storage tank, so the requirement for the material strength of the storage tank is greatly reduced. In addition, the design pressure of the ordinary CO2 storage tank 2 in the application should be greater than the working pressure (0.83 MPa), and can be 1.2 MPa or more, the purpose is to avoid damage to the storage tank due to the change of the pressure of CO2 in the storage tank.

[0043] At the same time, there are many gap spaces between the common CO2 storage tank 2 and the ship body or between the common CO2 storage tank 2 and the common CO2 storage tank 2 on the propane carrier, and the common CO2 storage tank 2 is placed in the cargo hold 1 containing liquid propane in the present application, liquid propane fills in the gap spaces, the gap spaces are fully utilized, the utilization rate of the ship body space is greatly improved, and the common CO2 storage tank is provided with a reasonable storage place, and the problem of the storage space of the captured CO2 during the voyage of the propane carrier is solved.

[0044] In addition, the common CO2 storage tank 2 is placed in the cargo hold 1 together with the liquid propane in the present application, and a part of the storage space of the liquid propane is occupied, so that the carrying capacity is appropriately reduced, and then the volume of the cargo hold 1 can be appropriately increased when the propane carrier is designed, so that the cargo hold 1 of the propane carrier can store liquid CO2 and ensure the carrying capacity of the liquid propane.

[0045] The above describes the specific embodiments of the present application by taking the common CO2 storage tank 2 as an example, and the specific embodiments of the common CO2 storage tank 2 placed in the No. 2 cargo hold are the same as the above.

[0046] The above only describes the preferred embodiments of the present application, but the implementation is not limited by the above embodiments, and it should be pointed out that: for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A CO2 capture storage system for a propane carrier, characterized by: The system comprises a cargo hold (1) and a common CO2 tank (2), The ship main engine is connected with the CO2 capture unit through a pipeline, one side of the CO2 capture unit is connected with the atmosphere through a pipeline, the other side of the CO2 capture unit is connected with the CO2 liquefaction unit through a pipeline, and the CO2 liquefaction unit is connected with the common CO2 tank (2) through a pipeline, The common CO2 tank (2) is a common pressure tank, and the surface of the tank body is not provided with a heat preservation layer; the working pressure of the common CO2 tank (2) is greater than or equal to 0.83 MPa, and the working temperature is -42℃, The common CO2 tank (2) is used for storing the liquid CO2 captured during the ship sailing, A plurality of common CO2 tanks (2) are arranged on the ship, and are placed in the cargo hold (1); all the common CO2 tanks (2) are placed in the same cargo hold in the cargo hold (1).

2. A CO2 capture storage system for a propane carrier as claimed in claim 1, characterized in that: The common CO2 tank (2) is preferentially placed in the No.2 cargo hold or the No.3 cargo hold close to the ship's center of buoyancy.

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