Liquefied co2 supply system, method for discharging liquefied co2, and method for starting supply of liquefied co2

Abstract

Provided is a technology for discharging liquefied CO2 in an apparatus while suppressing the formation of dry ice.　This liquefied CO2 supply system for supplying liquefied CO2 via an apparatus (1) comprises: a liquefied CO2 supply path (21) having a first opening / closing valve (211) for supplying the liquefied CO2 to the apparatus (1); a liquefied CO2 discharge path (22) having a second opening / closing valve (221) for discharging the liquefied CO2 from the apparatus (1); a purging fluid supply path (23) having a first purge valve (231) for supplying a purging fluid for pushing out the internal liquefied CO2 while increasing the pressure within the apparatus (1) to a purge pressure higher than at least the pressure at the triple point of CO2; and a first drain path (25) having a first drain valve (251) for discharging the purging fluid and the liquefied CO2.

Description

Liquid CO₂ supply system, method for discharging liquid CO₂, and method for starting supply of liquid CO₂

[0001] The present invention relates to a technique for discharging liquid CO ２ in equipment provided in a liquid CO supply system or starting the supply of liquid CO ２ to the equipment. ２

[0002] As a method for suppressing the atmospheric emission of carbon dioxide (CO ２ ) gas, which is one of the greenhouse gases, storage technologies (CCS: Carbon Capture and Storage) for storing CO ２ underground and the development of technologies for converting CO ２ into other substances such as methanol and using it are being promoted.

[0003] Here, in order to store and utilize CO ２ recovered from the combustion exhaust gas discharged by burning fuel in a thermal power plant or factory, the transportation of CO ２ may be required. The recovered CO ２ is transported, for example, in a liquefied state via a transport ship or a pipeline and supplied to a storage facility or a plant using CO ２ as a raw material. In carrying out the transportation of liquefied CO ２ , liquefied CO ２ tanks for temporarily storing liquefied CO ２ may be provided at both the recovery site and the storage / use site of liquefied CO ２ .

[0004] In the liquefied CO ２ tank, various equipment such as a pump for pumping liquefied CO ２ , a heat exchanger for heating and cooling liquefied CO ２ , and a compressor for boosting the CO ２ gas (boil-off gas, BOG) generated in the tank are installed together. Hereinafter, equipment including the liquefied CO ２ tank, the equipment installed together with it, and the piping connecting the liquefied CO ２ tank and the equipment or the equipment to each other is called a liquefied CO ２ supply system.

[0005] liquefied CO ２ The equipment installed in the supply system must be opened and maintained periodically or as needed. In order to open the equipment, liquefied CO2 inside the equipment must be removed. ２ It must be discharged. On the other hand, liquefied CO2 ２ It may be handled under temperature and pressure conditions relatively close to the solid-liquid-gas triple point (-56.6°C, 0.52 MPaA (4.2 Barg)). Therefore, liquefied CO2 inside the equipment ２ The pressure and temperature drops associated with the discharge process make it easy for dry ice to form. If dry ice forms, it can damage the equipment itself and cause liquefied CO2. ２ This could cause blockage in the pathway through which the fluid flows.

[0006] Patent Document 1 describes a filling device for filling a portable tank (high-pressure container) of a truck-mounted cryogenic refrigeration system with liquid carbon dioxide from a storage tank (low-pressure container) for liquid carbon dioxide. This filling device allows for automatic filling of liquefied carbon dioxide while maintaining a predetermined pressure inside the portable tank by providing pressure regulators (first pressure regulator, second pressure regulator) in both the conduit through which liquid carbon dioxide flows from the portable tank to the storage tank (inlet conduit) and the conduit through which gaseous carbon dioxide is discharged from the storage tank (discharge conduit). However, Patent Document 1 does not disclose the necessary configuration or method for discharging liquefied carbon dioxide from equipment installed within the filling device when performing maintenance on the equipment.

[0007] Also, liquefied CO2 ２Although the object being transported is different, Patent Document 2 describes a technology for transporting liquid hydrogen via a transport ship. According to Patent Document 2, when transporting liquid hydrogen between a first tank on land and a second tank on a hydrogen transport ship, two transport systems (first transport system, second transport system), each equipped with a loading arm, are connected to each other via a connecting passage, and the transport system is purged while avoiding freezing of the purge gas by using helium, which has a lower boiling point than hydrogen. However, although liquid hydrogen itself is not susceptible to freezing due to pressure drop or temperature drop, Patent Document 2 does not describe a technology to prevent the liquid being purged from freezing.

[0008] Japanese Patent Publication No. 2001-506357, Japanese Patent Publication No. 6489633

[0009] This invention was made against this background, and aims to suppress the formation of dry ice while controlling liquefied CO2 in the equipment. ２ We provide technology to discharge waste.

[0010] This liquefied CO ２ The supply system delivers liquefied CO2 via equipment. ２ Liquefied CO2 to supply ２ A supply system comprising the equipment containing the liquefied CO2 ２ A liquefied CO2 supplying a first on / off valve ２ The supply route and the liquefied CO2 from the equipment. ２ Liquefied CO2 with a second on / off valve for discharging CO2 ２ A discharge path is connected between the first or second on-off valve and the equipment, and the pressure inside the equipment is reduced to at least CO2. ２ While pressurizing to a purge pressure higher than the pressure at the triple point, the liquefied CO2 inside ２ A purge fluid supply path having a first purge valve that supplies a purge fluid to push out the liquefied CO2, and a connection between the second on-off valve or the first on-off valve and the equipment, which supplies the purge fluid and the liquefied CO2. ２ It comprises a first drain path having a first drain valve for discharging the following.

[0011] The aforementioned liquefied CO2 ２The supply system may include the following: (a) a purge fluid discharge path having a second purge valve connected between the second on-off valve or the first on-off valve and the equipment for discharging the purge fluid; (b) a connection between the first on-off valve or the second on-off valve and the equipment for discharging the purge fluid and the liquefied CO2. ２ (c) The purge fluid is CO ２ It is a gas. In this case, the first drain path is liquefied CO ２ To be connected to a tank. Furthermore, the CO ２ The gas is the liquefied CO2. ２ The liquefied CO2 in the tank ２ (d) The first drain path is connected to a drain drum and includes a pressurized fluid supply path having a pressure valve that supplies pressurized fluid to pressurize the pressure inside the drain drum to the purge pressure. The pressurized fluid is the purge fluid. (e) The equipment is a pump, heat exchanger, tower, tank, valve body or piping.

[0012] According to the present invention, the purge fluid supplied from the purge fluid supply path reduces the pressure inside the equipment to at least CO2. ２ While pressurizing to a purge pressure higher than the pressure at the triple point, the liquefied CO2 inside ２ Because it pushes out the liquefied CO2 inside the equipment while suppressing the formation of dry ice. ２ It can discharge.

[0013] liquefied CO ２ Liquefied CO2 from equipment installed in the supply system ２ This is a first explanatory diagram relating to the discharge operation. This is a second explanatory diagram relating to the discharge operation. This is a third explanatory diagram relating to the discharge operation. This is a fourth explanatory diagram relating to the discharge operation. This is a pressure-enthalpy diagram inside the equipment during the discharge operation. This is a diagram of liquefied CO2 in the equipment. ２ This is the first explanatory diagram relating to the supply initiation operation of the liquefied CO2. ２ This is a second explanatory diagram relating to the supply initiation operation of the liquefied CO2. ２ This is the third explanatory diagram relating to the supply initiation operation. Liquefied CO2２ Boil-off gas (CO2) discharged from the tank ２ This is an example of a system configuration for supplying liquefied CO2 (gas) as a purge fluid. ２ This is an example of the configuration of the receiving equipment. Liquefied CO2 from the receiving equipment. ２ This is a first explanatory diagram relating to the discharge operation of the receiving equipment. This is a second explanatory diagram relating to the discharge operation of the receiving equipment. This is a third explanatory diagram relating to the discharge operation of the receiving equipment. This is a fourth explanatory diagram relating to the discharge operation of the receiving equipment. This is a first explanatory diagram relating to the discharge operation of the receiving equipment according to another embodiment. This is a second explanatory diagram relating to the discharge operation of the receiving equipment according to another embodiment.

[0014] Hereinafter, with reference to Figures 1 to 4, we will describe the liquefied CO2 according to an embodiment of the present invention. ２ The configuration of the supply system, and this liquefied CO2 ２ Liquefied CO2 is supplied from equipment 1 installed in the supply system. ２ Here is an example of a method for discharging it.

[0015] liquefied CO ２ The supply system is, for example, as shown in Figure 9, liquefied CO2. ２ It consists of a tank 91 and various pieces of equipment attached thereto. Liquefied CO in this embodiment ２ Equipment to which this discharge method applies includes liquefied CO2. ２ It is installed in the supply system and contains liquefied CO2 inside. ２ There are no particular limitations as long as the equipment has the necessary components. For example, liquefied CO2 ２ Pump 95 for delivering liquid, liquefied CO2 ２ Ya CO ２ Heat exchangers used for heating and cooling gases, liquefied CO2 ２ and CO ２ Separation towers that perform gas-liquid separation with gas, and CO ２ Converting CO2 gas to liquefied CO2 ２ Towers and tanks such as knockout drums separate the mist, and liquefied CO2 is directed towards the transport ship. ２ Ship or transport liquefied CO2 from a transport ship ２ In order to accept it, the transport ship's route and liquefied CO2 ２ Loading arms that connect to the supply system's path, valve bodies such as control valves, and also liquid CO2２ Examples of the pipe body that constitutes the path through which the fluid flows can be given.

[0016] The liquefied CO ２ supply system according to the present embodiment may be installed in a thermal power plant or a factory, together with equipment for recovering and liquefying CO from the combustion exhaust gas of fuels containing hydrocarbons such as LNG (Liquefied Natural Gas), fuel oil, and coal. In this case, the recovered liquefied CO ２ is temporarily stored in the liquefied CO ２ tank 91, and then supplied (shipped) to a transportation means such as a transport ship or a pipeline. Also, the liquefied CO ２ supply system may be installed together with a CCS storage facility for storing liquefied CO in the ground or a plant for manufacturing other substances using CO as a raw material. In this case, the liquefied CO recovered at a thermal power plant or a factory ２ or the liquefied CO transported through a transport ship, a pipeline, etc. is temporarily stored in the liquefied CO ２ tank 91, and then supplied to the storage facility or the plant. ２ ２ ２ ２

[0017] Each device constituting the liquefied CO ２ supply system is maintained regularly or as needed. In this case, when there is liquefied CO inside the device ２ , the device cannot be opened or removed without discharging this liquefied CO ２ . Also, during a period when liquefied CO ２ is not being handled, such as in the case of the loading arm 281 described using FIG. 10 and others to be described later, the internal liquefied CO ２ may be discharged and the device may be made to standby in an inert gas atmosphere such as nitrogen gas.

[0018] On the other hand, as described in the background art, in the liquefied CO ２ supply system, liquefied CO may be handled under temperature and pressure conditions close to the triple point of CO ２ . In this case, for example, when handling liquefied CO in device 1 ２ ​２ When discharging it toward the low-pressure path, there is a risk of forming dry ice due to the pressure drop inside the device 1 and the temperature drop accompanying the vaporization of liquefied CO ２ and the adiabatic expansion of CO ２ gas. The formation of dry ice may cause damage to the device 1 itself and blockage of the path through which liquefied CO ２ flows.

[0019] Based on such problems, in the liquefied CO ２ supply system of this embodiment, the device 1 that handles liquefied CO ２ is configured to be able to discharge liquefied CO from inside the device 1 while suppressing the formation of dry ice. Furthermore, this liquefied CO ２ supply system can also be expected to discharge liquefied CO while suppressing the formation of dry ice in a short time. Hereinafter, the configuration and an example of the method for discharging liquefied CO ２ will be described while referring to FIGS. 1 to 4. In FIGS. 1 to 4 and FIGS. 6 to 8 described below, the device 1 provided in the liquefied CO ２ supply system is abstracted and shown in a box shape. This device 1 may be selected from the pump 95, heat exchanger, tower tank, loading arm 281, valve body, and pipe body as described above, or may be a device other than these examples. ２ ２

[0020] As shown in FIG. 1, a liquefied CO ２ supply path 21 is connected to the inlet side of the device 1. A first partition valve 211, which is a first on-off valve, is provided in the liquefied CO ２ supply path 21. By opening this first partition valve 211, liquefied CO ２ can be supplied to the device 1. Also, a liquefied CO ２ discharge path 22 is connected to the outlet side of the device 1. A second partition valve 221, which is a second on-off valve, is provided in the liquefied CO ２ discharge path 22. By opening this second partition valve 221, liquefied CO ２ can be discharged from the device 1.

[0021] ​​A purge fluid supply path 23 is connected between the first gate valve 211 or the second gate valve 221 and the equipment 1. A first purge valve 231 is provided in the purge fluid supply path 23. By opening this first purge valve 231, purge fluid can be supplied into the equipment 1. In the example shown in Figure 1, liquefied CO2 ２ A purge fluid supply path 23 is connected between the first gate valve 211 on the supply path 21 side and the equipment 1, but the location where the purge fluid supply path 23 is connected is not limited to this example. For example, liquefied CO ２ The purge fluid supply path 23 may be connected between the second gate valve 221 on the discharge path 22 side and the equipment 1. Alternatively, the purge fluid supply path 23 may be connected directly to the equipment 1. Therefore, the configuration in this embodiment in which the purge fluid supply path 23 is "connected between the first gate valve 211 or the second gate valve 221 and the equipment 1" also includes the case in which the purge fluid supply path 23 is connected directly to the equipment 1.

[0022] The purging fluid is liquefied CO2 inside equipment 1. ２ It plays the role of pushing it out. As a purging fluid, after being discharged from equipment 1, liquefied CO2 ２ CO2 does not require separation. ２ An example of using gas can be given. CO ２ As a gas supply source, liquefied CO2 ２ Liquefied CO in tank 91 ２ An example is the use of boil-off gas (BOG) obtained by vaporization. An example of the configuration of equipment for supplying BOG as a purge fluid is explained in Figure 9 below. Here, CO is used as the purge fluid. ２ When using gas, liquefied CO2 inside equipment 1 ２ After pushing out the CO, when performing a depressurization operation to reduce the pressure inside the device 1, the CO ２ It is preferable that the temperature is such that dry ice does not form from the gas. In this regard, the CO used as the purging fluid is ２ The gas temperature can be exemplified as room temperature (around 20-25°C).

[0023] However, CO2 is used as the purging fluid. ２Using gas is not a mandatory requirement. Under the pressure conditions when discharging from equipment 1, CO ２ Other types of gases or liquids may be used as long as they have a temperature higher than the melting point of CO2. Examples of other types of fluids include nitrogen gas, liquefied nitrogen, and helium gas. Note that liquefied CO2 is emitted from equipment 1. ２ liquefy CO2 ２ When returning to tank 91, liquefied CO ２ and CO ２ It is preferable to perform a separation operation with the purge fluid, which is a different type of gas.

[0024] Furthermore, the purging fluid is liquefied CO2 inside the equipment 1. ２ When pushing out, the pressure inside the device 1 is at least CO ２ It also plays a role in pressurizing the system to a pressure higher than the pressure at the triple junction (hereinafter also referred to as "purge pressure").

[0025] As shown in the example in Figure 1, a first drain path 25 may be connected between the second gate valve 221 or the first gate valve 211 and the equipment 1. A first drain valve 251 is provided in the first drain path 25. By opening this first drain valve 251, purge fluid and liquefied CO2 can be discharged from the equipment 1. ２ It can discharge CO2. In the example shown in Figure 1, liquefied CO2 can be discharged. ２ A first drain path 25 is connected between the second gate valve 221 on the discharge path 22 side and the equipment 1, but the location where the first drain path 25 is connected is not limited to this example. For example, liquefied CO ２ The first drain route 25 may be connected between the first gate valve 211 on the supply route 21 side and the equipment 1. Alternatively, the first drain route 25 may be connected directly to the equipment 1. Therefore, the configuration in this embodiment in which the first drain route 25 is "connected between the second gate valve 221 or the first gate valve 211 and the equipment 1" also includes the case in which the first drain route 25 is connected directly to the equipment 1.

[0026] Furthermore, as shown in the example in Figure 1, a purge fluid discharge path 24 may be connected between the second gate valve 221 or the first gate valve 211 and the equipment 1. A second purge valve 241 is provided in the purge fluid discharge path 24. By opening this second purge valve 241, the purge fluid can be discharged from the equipment 1. In the example shown in Figure 1, liquefied CO2 ２ A purge fluid discharge path 24 is connected between the second gate valve 221 on the discharge path 22 side and the equipment 1, but the location where the purge fluid discharge path 24 is connected is not limited to this example. For example, liquefied CO ２ A purge fluid discharge path 24 may be connected between the first gate valve 211 on the supply path 21 side and the equipment 1.

[0027] In addition to the above configuration, as shown in the example in Figure 1, liquefied CO ２ When the first drain path 25 is connected between the second gate valve 221 on the discharge path 22 side and the equipment 1, liquefied CO ２ A second drain path 26 may be connected between the first gate valve 211 on the supply path 21 side and the equipment 1. A second drain valve 261 is provided in the second drain path 26. By opening this second drain valve 261, the purge fluid and liquefied CO can also be discharged from the equipment 1. ２ It can discharge CO2. In the example shown in Figure 1, liquefied CO2 can be discharged. ２ A second drain path 26 is connected between the first gate valve 211 on the supply path 21 side and the equipment 1, but the location where the second drain path 26 is connected is not limited to this example. For example, liquefied CO ２ If the first drain path 25 is connected between the first gate valve 211 on the supply path 21 side and the equipment 1, liquefied CO ２ The second drain path 26 may be connected between the second gate valve 221 on the discharge path 22 side and the equipment 1. Alternatively, the second drain path 26 may be connected directly to the equipment 1. Therefore, the configuration in this embodiment in which the second drain path 26 is "connected between the first gate valve 211 or the second gate valve 221 and the equipment 1" also includes the case in which the second drain path 26 is connected directly to the equipment 1.

[0028] Liquefied CO2 having the configuration described above ２In equipment 1 installed in the supply system, liquefied CO ２ We will explain the methods for emitting CO2. First, liquefied CO2 ２ First gate valve 211 of supply path 21 and liquefied CO ２ The second gate valve 221 of the discharge path 22 is changed from the open state to the closed state (the process of closing the first on-off valve and the second on-off valve; Figure 1). This operation causes liquefied CO2 to be discharged from the upstream side of the first gate valve 211. ２ Liquefied CO2 on the downstream side of the supply path 21 and the second gate valve 221 ２ Equipment 1 is disconnected from the discharge path 22. At this time, the first drain valve 251 of the first drain path 25, the second drain valve 261 of the second drain path 26, and the second purge valve 241 of the purge fluid discharge path 24 are closed beforehand. In the diagrams showing the valves, valves outlined in white indicate the "open" state, and valves filled in black indicate the "closed" state.

[0029] For example, liquefied CO2 ２ When the supply system is operational, if a backup unit is installed in parallel with unit 1, liquefied CO ２ After switching the flow to the replacement machine, the equipment 1 to be maintained is disconnected. Also, if equipment 1 is a moving piece of equipment, such as pump 95, the equipment 1 is stopped before disconnection. For example, liquefied CO ２ Like the inspection of opening tank 91, liquefied CO ２ If disconnecting equipment 1 is to be performed after shutting down the entire supply system, disconnect equipment 1 after the shutdown operation is completed.

[0030] Subsequently, the liquefied CO2 described above ２ Supply route 21, liquefied CO ２ As the operation to close the discharge path 22 is performed, the operation to open the first purge valve 231 of the purge fluid supply path 23 is performed (Figure 2). Here, for example, liquefied CO2 in the equipment 1 is opened. ２ Let's assume that the temperature and pressure are near the triple point (-56.6°C, 0.52 MPaA (4.2 Barg)). In this case, if only the first drain valve 251 of the first drain path 25, or both the first drain valve 251 of the first drain path 25 and the second drain valve 261 of the second drain path 26 are opened, the liquefied CO inside the device 1 will be drained. ２It is discharged by its own pressure.

[0031] CO in equipment 1 at this time ２ The change in state (phase change) will be explained with reference to the pressure-enthalpy diagram in Figure 5. The horizontal axis of Figure 5 is CO ２ Enthalpy of CO2, vertical axis is CO2 ２ This shows the pressure. In the diagram, the symbols "S, L, V" represent the solid phase, liquid phase, and gas phase, respectively. In this case, for example, "L + V" indicates a mixed state of liquid and gas phases, and "S + V" indicates a mixed state of solid and gas phases. Also, "S.C." indicates a supercritical state, and "c.p." indicates a critical point.

[0032] In Figure 5, CO ２ From the state marked with an "X" near the triple point, as previously described, liquefaction of CO2 occurs due to self-pressure. ２ Let's assume that CO2 is discharged from device 1. In this case, the pressure inside device 1 decreases during the enthalpy process, such as when there is no heat input from the outside. As a result, liquefied CO2 is produced, as shown by the dashed arrow in Figure 5. ２ As the pressure decreases, the mixture changes from a state where the liquid phase and gas phase coexist (L+V) to a state where the solid phase and gas phase coexist (S+V), resulting in the formation of dry ice.

[0033] Therefore, in this embodiment, along the arrows shown by solid lines in Figure 5, the purging fluid is CO ２ While pressurizing with gas (maintaining the pressure of a mixed state of liquid and gas phases), liquefy CO2 inside device 1. ２ Warmer CO ２ Replace with gas (replacement operation shown in Figure 5). Then, the CO inside equipment 1 ２ The gas is discharged to reduce the pressure inside equipment 1 (depressurization operation shown in Figure 5). These displacement and depressurization operations are performed even when nitrogen gas or helium gas is used as the purge fluid, CO ２ It produces the same effects as when using gas.

[0034] To perform the two operations described above, after disconnecting the equipment 1 as explained in Figure 1, the first purge valve 231 of the purge fluid supply path 23 is opened, and the purge fluid CO ２ To supply gas. CO ２The gas supply pressure is CO ２ There are no particular limitations as long as the pressure is higher than the pressure at the triple point (0.52 MPaA (4.2 Barg)), CO ２ The pressure may be controlled to be higher than the pressure at the triple point of CO2. ２ The pressure is increased to a purge pressure higher than the pressure at the triple point (the pressure inside the equipment is at least CO2). ２ The process of pressurizing the equipment to a purge pressure higher than the pressure at the triple point. Hereafter, this will also be simply referred to as the "process of pressurizing the inside of the equipment." (Figure 2).

[0035] Subsequently, either the first drain valve 251 of the first drain path 25, or both the first drain valve 251 of the first drain path 25 and the second drain valve 261 of the second drain path 26 are opened to allow liquefied CO2 to drain from the device 1. ２ and CO ２ Discharge the gas (purging fluid) (purging fluid and the liquefied CO2). ２ The process of discharging the wastewater. (Figure 3). Note that Figure 3 shows an example in which only the first drain valve 251 of the first drain path 25 is opened.

[0036] Here, the downstream side of the first drain path 25 and the second drain path 26 is, for example, liquefied CO ２ It is connected to tank 91. With this configuration, liquefied CO2 discharged from equipment 1 ２ This involves liquefying CO2 while maintaining a pressure that allows it to remain in a liquid state (and suppress the formation of dry ice). ２ It can be recovered into tank 91. Therefore, for example, CO ２ Unlike the configuration when the fluid is discharged into an atmospheric pressure atmosphere, the first drain path 25 and the second drain path 26 are used for purging the CO2 fluid. ２ Liquefied CO2 discharged under pressurized gas ２ It is composed of piping that has pressure resistance performance corresponding to the pressure.

[0037] Thus, CO2 enters the inside of device 1. ２Once replaced by gas, either only the first drain valve 251 of the first drain path 25, or both the first drain valve 251 of the first drain path 25 and the second drain valve 261 of the second drain path 26 are closed. Then, the second purge valve 241 of the purge fluid discharge path 24 is opened to allow CO to escape from the equipment 1. ２ The gas is discharged (the process of discharging the purge fluid; Figure 4).

[0038] The liquefied CO2 described above ２ According to the discharge method, the purge fluid supplied from the purge fluid supply path 23 (for example, CO ２ The gas reduces the pressure inside the device 1 to at least CO2. ２ While pressurizing to a purge pressure higher than the pressure at the triple point, the liquefied CO2 inside ２ This pushes out the liquefied CO2 inside the device 1 while suppressing the formation of dry ice. ２ It can discharge.

[0039] In the example described above using Figures 1 to 4, the liquefied CO2 inside the device 1 ２ The article described methods to suppress the formation of dry ice when discharging CO2. Conversely, it also discussed maintenance and liquefied CO2. ２ After completing the standby period with the CO2 discharged, liquefied CO2 is supplied to equipment 1. ２ There is a risk that dry ice may form when supplying the product.

[0040] In other words, the inside of equipment 1 after maintenance or in standby mode is at room temperature and atmospheric pressure. Liquefied CO2 is inside this equipment 1. ２ Liquefied CO2 from supply route 21 ２ When supplied, for example, liquefied CO2 at -56.6°C or below ２ However, it comes into contact with the room temperature device 1 and is heated. As a result, liquefied CO ２ While some of it vaporizes and the temperature drops, equipment 1 may be damaged by the rapid temperature change. In parallel with this, high-pressure liquefied CO2 ２ Liquefied CO2 supplied from supply path 21 into equipment 1 at atmospheric pressure ２ In this case, the pressure decreases, and dry ice is formed along the same path as the dashed arrow shown in Figure 5.

[0041] Therefore, in order to prevent the formation of dry ice inside equipment 1 and damage to equipment 1, first, a pressurization operation should be performed inside equipment 1, following the direction of the solid arrow in Figure 5, and then CO ２ Converting CO2 gas to liquefied CO2 ２ A replacement operation needs to be performed. Figures 6 to 8 show the liquefied CO2 in such equipment 1. ２ This shows an example of how to begin supplying the product.

[0042] In the examples shown in Figures 6 to 8, components common to the examples described using Figures 1 to 4 are denoted by the same reference numerals as those shown in Figures 1 to 4. That is, as in the examples described using Figures 1 to 4, the equipment 1 is connected to pathways 21, 22, 23, 25, 16, and 24, each equipped with valves 211, 221, 231, 251, 261, and 241. However, the liquefied CO2 described below... ２ When applying the supply initiation method, the second purge valve 241 provided in the purge fluid discharge path 24 may be configured as a pressure regulating valve 240 as shown in Figures 6 to 8. This pressure regulating valve 240 controls the pressure inside the device 1 based on the pressure detection result of the pressure gauge 11 provided in the device 1. ２ It plays a role in maintaining a purge pressure higher than the pressure at the triple point.

[0043] In the equipment 1 after maintenance or in standby mode, all of the valves 211, 221, 231, 251, 261, and 241 described above are closed. In this state, the first purge valve 231 of the purge fluid supply path 23 is opened, and the purge fluid CO is supplied into the equipment 1. ２ The gas is supplied, and the pressure inside the device 1 is set to the CO2 level described above. ２ The system is pressurized to a purge pressure higher than the pressure at the triple point (a process of pressurizing the inside of the equipment; Figure 6).

[0044] Next, the first purge valve 231 of the purge fluid supply path 23 is closed, while liquefied CO ２ Open the first gate valve 211 of the supply path 21 and let liquefied CO into the equipment 1. ２ The device 1 is cooled by introducing the following (cooling process for the device; Figure 7). In practice, instead of directly opening the first gate valve 211, liquefied CO2 is introduced. ２A small valve (neither the small pipe nor the small valve is shown) located in a small pipe branching off from the supply route 21 and connected to equipment 1 is opened, and liquefied CO2 is supplied at a small flow rate. ２ You may implement this (hereinafter also referred to as "cooldown operation").

[0045] While performing this cool-down operation, the second purge valve 241 of the purge fluid discharge path 24 is opened (pressure adjustment is performed by the pressure regulating valve 240), and the pressure inside the equipment 1 is reduced to CO ２ While maintaining a purge pressure higher than the triple point pressure, the CO generated during the cool-down operation ２ Emits gas (CO ２ (Gas discharge process, Figure 8). In this way, the temperature of equipment 1 is reduced by liquefied CO2. ２ Once cooled to a similar level and the cool-down operation is complete, liquefied CO2 ２ The second gate valve 221 of the discharge path 22 is opened, and the second purge valve 241 of the purge fluid discharge path 24 is closed. Then, a small flow rate of liquefied CO2 is discharged. ２ Stop the introduction of liquefied CO2 ２ Open the first gate valve 211 of the supply path 21 to liquefy CO2 ２ We will begin full-scale supply.

[0046] The liquefied CO2 described above ２ According to the method of starting the supply, the purge fluid (e.g., CO) supplied from the purge fluid supply path 23 ２ The gas reduces the pressure inside equipment 1 to CO2. ２ After pressurizing to a purge pressure higher than the pressure at the triple point, liquefied CO2 is introduced into the device 1. ２ This will be introduced. As a result, the formation of dry ice will be suppressed while liquefying CO2 ２ This allows the device 1 to be cooled.

[0047] Figure 9 shows liquefied CO2. ２ BOG (CO2) generated in tank 91 ２ This shows an example of equipment configuration that utilizes liquefied CO2 as a purging fluid. ２The gaseous gas generated in the tank 91 is supplied to the gaseous gas compressor 92 via the gaseous gas intake path 913, where it is pressurized and then flows towards the high-pressure gaseous gas discharge path 914. Depending on the purpose, this gaseous gas is sent to the destination or storage location either in its gaseous state, or after being cooled or liquefied.

[0048] In this configuration, CO is boosted by the BOG compressor 92. ２ A high-pressure BOG discharge branch path 915 is provided to extract a portion of the gas, and the extracted CO ２ The gas is stored in the holder tank 941. This holder tank 941 contains CO ２ The base end of the main gas supply route 944 is connected, and furthermore, the CO ２ The main gas supply route 944 is liquefied CO2 ２ It is connected to multiple utility stations (not shown) located within the supply system site. By connecting these utility stations to the purge fluid supply path 23 with hoses or temporary piping, CO2 is supplied to each device 1. ２ Gas can be supplied. A pressure control valve 942 is provided in the high-pressure BOG discharge branch path 915, and based on the result of detecting the pressure in the holder tank 941 with a pressure gauge 943, CO is supplied via the purge fluid supply path 23. ２ Gas pressure CO ２ The pressure of the holder tank 941 is adjusted so that the purge pressure is higher than the pressure at the triple point.

[0049] Next, liquefied CO2 ２ Equipment 1 from which emissions occur includes liquefied CO2 from a transport ship. ２ An example of its application to receiving equipment will be explained. Figure 10 shows liquefied CO2. ２ Figures 11 to 14 show the state in which the supply is being carried out, and Figures 15 and 16 are explanatory diagrams of another embodiment. In these figures as well, components common to the embodiment described using Figures 1 to 4 are denoted by the same reference numerals as those shown in Figures 1 to 4.

[0050] Figure 10 shows liquefied CO2 via the receiving equipment. ２ This shows the state of receiving the liquefied CO2.２ A loading arm 281 is connected to the end of the ship-side gate valve 411 on the transport ship side, and the ship-side liquefied CO2 is supplied. ２ Ship-side gate valve 411 provided in the supply path 41, and liquefied CO ２ The second gate valve 221 of the discharge path 22 is opened. As a result, the loading arm 281 and the liquefied CO connected to the loading arm 281 are opened. ２ Liquefied CO2 via supply route 282 ２ Liquefied CO2 directed towards discharge path 22 ２ This is discharged. Thus, in this embodiment, the liquefied CO2 on the transport ship side is discharged. ２ Supply route 41 is liquefied CO ２ The supply route 21 is performed by the ship's side gate valve 411, and these liquefied CO2 ２ It can be said that the supply route 21 and the first gate valve 211 are externally mounted.

[0051] In this embodiment, as viewed from the loading arm 281, which is equipment 1, the lower end of the loading arm 281 and liquefied CO ２ The purge fluid supply path 23 and the first drain path 25 are connected to the second gate valve 221 of the discharge path 22. Thus, the purge fluid supply path 23 and the first drain path 25 do not necessarily have to be connected with the device 1 in between. Also, the piping is liquefied CO ２ Equipment 1 subject to emission includes liquefied CO2 ２ In the supply path 282, the connection point of the purge fluid supply path 23 corresponds to "the position between the upstream end of the loading arm 281 and the ship's gate valve 411 (first gate valve 211)", and the connection point of the first drain path 25 corresponds to "liquefied CO ２ This corresponds to the position between the downstream end of the supply path 282 and the second gate valve 221. This first drain path 25 allows the loading arm 281, which is provided between the ship's gate valve 411 and the second gate valve 221, to liquefy CO ２ Liquefied CO2 from the entire system, including supply path 282 ２ Discharge occurs.

[0052] Furthermore, in the embodiments shown in Figures 10 to 14, a loading arm 281 and liquefied CO2 are directed toward a drain drum 3 that is provided independently. ２ Liquefied CO2 remaining in supply path 282 (equipment 1) ２ The system is configured to discharge liquefied CO2. Specifically, the end of the first drain path 25 is connected to the drain drum 3, and when the first drain valve 251 is opened, liquefied CO2 is discharged towards the drain drum 3. ２ It is discharged.

[0053] On the other hand, as previously mentioned, liquefied CO2 ２ Unlike tank 91, the inside of drain drum 3 is CO ２ The pressure may be lower than the pressure at the triple point. In this case, liquefied CO2 ２ There is a risk that dry ice may form when the CO2 is discharged into the drain drum 3. Therefore, in this embodiment, for example, a pressurized fluid supply path 27 is provided, which is branched from the purge fluid supply path 23 upstream of the first purge valve 231, and the end of this path is connected to the drain drum 3. A pressurized valve 232 is provided in the pressurized fluid supply path 27, and when this pressurized valve 232 is opened, the purge fluid CO2 is discharged. ２ The gas is supplied to the drain drum 3 as a pressurized fluid.

[0054] However, using a purge fluid as the pressurized fluid is not a mandatory requirement, and a fluid other than the purge fluid may be used. For example, if the purge fluid is CO ２ Examples of cases where the pressurized fluid is a gas include nitrogen gas or helium gas. In this case, the base end of the pressurized fluid supply path 27 is connected to a pressurized gas supply path that is independent of the purge fluid supply path 23.

[0055] The loading arm 281 and liquefied CO2 described above ２ Liquefied CO2 in the receiving facility including supply route 282 ２ The discharge operation will be explained. As explained using Figure 10, liquefied CO2 from the ship ２ Liquefied CO2 via supply route 41 ２ The acceptance process will be carried out, and once this work is completed, the ship's liquefied CO2 will be carried out as shown in Figure 11. ２Close the ship-side gate valve 411 of the supply route 41 to liquefy CO ２ We will discontinue supplying it.

[0056] When a signal is received from the transport ship indicating that the ship's gate valve 411 has been closed, as shown in the figure, liquefied CO ２ The second gate valve 221 at the downstream end of the supply path 282 is closed. Then, as shown in Figure 11, the pressure valve 232 of the pressurized fluid supply path 27 is opened, and CO2 is supplied through the pressurized fluid supply path 27. ２ Gas is supplied and the drain drum 3 is pressurized. The drain drum 3 is CO ２ The system is pressurized to a purge pressure higher than the pressure at the triple point (a process of pressurizing the inside of the drain drum).

[0057] Once the drain drum is pressurized in this way, as shown in Figure 12, the pressurizing valve 232 is closed while the first purge valve 231 of the purge fluid supply path 23 is opened, and the loading arm 281, which is equipment 1, and liquefied CO2 are supplied. ２ CO, which is a purge fluid, enters the receiving equipment system, including the supply route 282. ２ The gas is supplied (the process of pressurizing the inside of the equipment).

[0058] Then, as shown in Figure 13, while continuing to pressurize the drain drum 3, the first drain valve 251 of the first drain path 25 is opened, and liquefied CO2 is released from within the receiving equipment system. ２ and CO ２ Discharge the gas (purge fluid) (purge fluid and liquefied CO2). ２ (The process of discharging CO2). In this way, the system of the receiving facility becomes CO2 ２ Once replaced with gas, the first drain valve 251 of the first drain path 25 is closed as shown in Figure 14. Then, the second purge valve 241 of the purge fluid discharge path 24 is opened to release the CO from inside the equipment 1. ２ The gas is discharged (the process of discharging the purge fluid; Figure 14).

[0059] Next, Figures 15 and 16 show that instead of providing a drain drum 3, the end of the first drain path 25 is connected to the liquefied CO2 downstream of the second gate valve 221. ２ The system is configured to merge with the discharge path 22. In this case as well, as shown in Figure 15, first the first purge valve 231 of the purge fluid supply path 23 is opened, and the purge fluid CO２ The gas is supplied (a process of pressurizing the equipment). Then, as shown in Figure 16, the first drain valve 251 of the first drain path 25 is opened, and liquefied CO is released from the receiving equipment system. ２ and CO ２ Discharge the gas (purge fluid) (purge fluid and liquefied CO2). ２ (Process for discharging CO2). As previously described, the downstream side of the second gate valve 221 is liquefied CO2. ２ Since it is connected to tank 91, liquefy CO2 at a pressure that does not form dry ice. ２ and CO ２ It can emit gas.

[0060] 1 Equipment 11 Pressure gauge 21 Liquefied CO ２ Supply route 211 First gate valve 22 Liquefied CO ２ Discharge route 221 Second gate valve 23 Purge fluid supply route 231 First purge valve 232 Pressure valve 24 Purge fluid discharge route 240 Pressure regulating valve 241 Second purge valve 25 First drain route 251 First drain valve 26 Second drain route 261 Second drain valve 27 Pressurized fluid supply route 281 Loading arm 282 Liquefied CO ２ Supply route 3 Drain drum 41 Shipside liquefied CO ２ Supply route 411 Shipside gate valve 91 Liquefied CO ２ Tank 911 Liquefied CO ２ Receiving route 912 Liquefied CO ２ Discharge route 913 BOG suction route 914 High-pressure BOG discharge route 915 High-pressure BOG discharge branch route 92 BOG compressor 941 Holder tank 942 Pressure regulating valve 943 Pressure gauge 944 CO ２ Gas supply main route 95 pumps

Claims

1. A liquefied CO supply system that supplies liquefied CO through a device ２ , ２ , ２ The liquefied CO supply system includes: a liquefied CO supply path having a first on-off valve for supplying the liquefied CO to the device ２ a liquefied CO discharge path having a second on-off valve for discharging the liquefied CO from the device ２ a purge fluid supply path having a first purge valve that is connected between the first on-off valve or the second on-off valve and the device and supplies a purge fluid for extruding the internal liquefied CO while pressurizing the pressure inside the device to a purge pressure higher than at least the triple point pressure of CO ２ a first drain path having a first drain valve that is connected between the second on-off valve or the first on-off valve and the device and discharges the purge fluid and the liquefied CO ２ The liquefied CO supply system is provided with the above components ２ connected between the first on-off valve or the second on-off valve and the device, and pressurizes the pressure inside the device to a purge pressure higher than at least the triple point pressure of CO while extruding the internal liquefied CO ２ A purge fluid supply path having a first purge valve for supplying a purge fluid for extruding the internal liquefied CO while pressurizing the pressure inside the device to a purge pressure higher than at least the triple point pressure of CO ２ connected between the second on-off valve or the first on-off valve and the device, and a first drain path having a first drain valve for discharging the purge fluid and the liquefied CO ２ A liquefied CO supply system comprising the above components ２ Supply system 2. The liquefied CO2 according to claim 1, comprising a purge fluid discharge path connected between the second on-off valve or the first on-off valve and the equipment, and having a second purge valve for discharging the purge fluid. ２ Supply system.

3. Connected between the first on-off valve or the second on-off valve and the equipment, the purge fluid and the liquefied CO2 ２ Liquefied CO2 according to claim 1 or claim 2, comprising a second drain path having a second drain valve for discharging CO2 ２ Supply system 4. The purging fluid is CO ２ Liquefied CO2 according to any one of claims 1 to 3, which is a gas ２ Supply system.

5. The first drain path is for liquefied CO ２ Liquefied CO2 according to claim 4, connected to a tank ２ Supply system.

6. The aforementioned CO ２ The gas is the liquefied CO2. ２ The liquefied CO2 in the tank ２ The liquefied CO2 according to claim 5 is a vaporized boil-off gas. ２ Supply system.

7. The liquefied CO2 according to any one of claims 1 to 6, wherein the first drain path is connected to a drain drum and comprises a pressurized fluid supply path having a pressure valve that supplies pressurized fluid to increase the pressure inside the drain drum to the purge pressure. ２ Supply system.

8. The liquefied CO2 according to claim 7, wherein the pressurized fluid is the purge fluid. ２ Supply system.

9. The liquefied CO2 according to any one of claims 1 to 8, wherein the equipment is a pump, heat exchanger, tower, tank, valve body, or piping. ２ Supply system.

10. Liquefied CO ２ Liquefied CO2 from equipment installed in the supply system ２ A method for discharging CO2, wherein the equipment contains the liquefied CO2. ２ Liquefied CO2 to supply ２ A first on / off valve is provided in the supply path, and the liquefied CO2 is supplied from the equipment. ２ Liquefied CO2 emissions ２ The process involves closing a second on-off valve provided in the discharge path, and then opening a first purge valve provided in a purge fluid supply path connected between the first on-off valve or the second on-off valve and the equipment, supplying purge fluid into the equipment, and reducing the pressure inside the equipment to at least CO2. ２ The process involves pressurizing the system to a purge pressure higher than the pressure at the triple point, and while performing the pressurizing process, opening the first drain valve provided in the first drain path connected between the second on-off valve or the first on-off valve and the equipment, thereby releasing the purge fluid and the liquefied CO2 from the equipment. ２ A process for discharging CO2, and liquefied CO2 including ２ Discharge method.

11. The liquefied CO2 according to claim 10, further comprising the step of, after performing the discharge step, opening a second purge valve provided in a purge fluid discharge path connected between the second on-off valve or the first on-off valve and the equipment, and discharging the purge fluid from the equipment. ２ Discharge method.

12. In the discharge step, the first drain valve is opened, or instead of opening the first drain valve, the second drain valve provided in the second drain path connected between the first on-off valve or the second on-off valve and the equipment is opened, and the purge fluid and the liquefied CO2 are discharged from the equipment. ２ Liquefied CO2 according to claim 10 or claim 11, which discharges CO2. ２ Discharge method.

13. The purging fluid is CO ２ Liquefied CO2 according to any one of claims 10 to 12, which is a gas. ２ Discharge method.

14. The first drain pathway is for liquefied CO ２ Liquefied CO2 according to claim 13, connected to a tank ２ Discharge method.

15. The aforementioned CO ２ The gas is the liquefied CO2. ２ The liquefied CO2 in the tank ２ The liquefied CO2 according to claim 14 is a vaporized boil-off gas. ２ Discharge method.

16. The first drain path is connected to a drain drum, and before performing the discharge step, the liquefied CO2 according to any one of claims 10 to 15 includes the step of opening a pressurizing valve provided in a pressurized fluid supply path connected to the drain drum and pressurizing the pressure inside the drain drum to the purge pressure. ２ Discharge method.

17. The liquefied CO2 according to claim 16, wherein the pressurized fluid is the purge fluid. ２ Discharge method.

18. The liquefied CO2 according to any one of claims 10 to 17, wherein the equipment is a pump, compressor, tower, tank, loading arm, valve body, or piping. ２ Discharge method.

19. Liquefied CO ２ Liquefied CO2 is supplied to the equipment installed in the supply system. ２ A method for initiating the supply of the liquefied CO2, wherein the equipment is connected to the equipment. ２ Liquefied CO2 to supply ２ A first on / off valve is provided in the supply path, and the liquefied CO2 is supplied from the equipment. ２ Liquefied CO2 emissions ２ With the second on-off valve provided in the discharge path closed, the first purge valve provided in the purge fluid supply path connected between the first on-off valve or the second on-off valve and the equipment is opened, and purge fluid is supplied into the equipment, pressurizing the pressure inside the equipment to a purge pressure at least higher than the pressure of the CO2 triple point. After performing the pressurizing step, the first on-off valve is opened, and the liquefied CO2 is supplied into the equipment. ２ The steps include introducing a gas to cool the equipment, and opening a purge valve provided in a purge fluid discharge path connected between the second or first on-off valve and the equipment, and maintaining a state in which the pressure inside the equipment is above the predetermined value, while discharging the CO generated in the cooling step from the equipment. ２ The process of discharging gas, including liquefied CO2 ２ How to start supplying it.

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