KR20100125625A - Method for preventing low-pressure in co2 reservoir - Google Patents

Abstract

PURPOSE: A low pressure prevention system for a carbon dioxide storage tank is provided to prevent the pressure reduction of a carbon dioxide storage tank during unloading of liquefied carbon dioxide. CONSTITUTION: A low pressure prevention system for a carbon dioxide storage tank is as follows. A liquid inlet pipe in which liquefied carbon dioxide flows is prepared. A liquid discharge pipe for discharging the stored liquefied carbon dioxide to outside is prepared. The hydraulic pressure of the liquefied carbon dioxide stored in of a carbon dioxide storage tank is measured(S-1). The measured pressure is compared with the set pressure(S-2). When the measured pressure is lowered below the set pressure, the flow of liquefied carbon dioxide in the liquid inlet pipe and the liquid outlet pipe is cut off. When the measured pressure is higher than the set pressure, pressure measurement is carried out again.

Description

Method for preventing low-pressure in CO2 reservoir

The present invention relates to a method of operating a storage tank in which liquid carbon dioxide is stored, and more particularly, to a method for preventing low pressure of a carbon dioxide storage tank to prevent liquid carbon dioxide from solidifying or rapidly evaporating as the internal pressure of the storage tank is lowered.

Carbon dioxide, released in large quantities due to increased use of fossil fuels, is designated as one of the Greenhouse Gases (GHGs) that cause global warming. Carbon dioxide is classified as a very important greenhouse gas because its global warming index is lower than other greenhouse gases, but it accounts for approximately 80% of the total greenhouse gas emissions and also regulates emissions. Therefore, various international agreements regulate countries to reduce greenhouse gas emissions. One of the technologies derived from this is the amount of carbon dioxide released into the atmosphere by recovering carbon dioxide from various industrial sites and storing it in a separate place. CO2 treatment technology has been introduced to reduce the pressure.

Treatment steps to reduce carbon dioxide emissions are largely carried out through four stages: carbon dioxide recovery, separation, concentration, transport and storage.

Exhaust gas containing carbon dioxide generated in the industrial field is recovered and separated and concentrated to only high concentration of carbon dioxide. The separation and concentration technology of the carbon dioxide is made through an absorption process, an adsorption process, or a membrane separation process as is known.

On the other hand, the triple point of carbon dioxide is known as -56.3 ℃, 0.517MPa, and the carbon dioxide separated and concentrated through the above process is cooled and compressed to phase change into a liquid state, so that a large amount of carbon dioxide can be stored in a tank having a limited space. do. The liquefaction of carbon dioxide can be achieved by dedicating various known means, such as expansion, multistage cooling, mixed cooling, which are widely used for liquefaction of natural gas.

In addition, transportation of liquefied carbon dioxide is known to be more economical to use a ship than to use a pipe when the transport distance is more than 1000km. Therefore, in the transportation of carbon dioxide between countries, a ship is appropriate as a means of transporting carbon dioxide, and a ship for transporting carbon dioxide should have a tank facility capable of maintaining a liquefied state of carbon dioxide cooled at high pressure and low temperature.

Existing ships capable of carrying pressurized, low temperature liquefied gas include compressed natural gas (PLNG) transport ships (ExxonMobil, US2005 / 037245). A transport tank for transporting natural gas in a liquefied state of approximately 1.7 MPa, -115 ° C is presented.

In addition, there are LPG carriers that transport pressurized LPG (LPG) by technology in a similar field. One of the widely used LPG carriers is equipped with a low-temperature, high-pressure pressure tank, similar to the conditions of the transport tank for carbon dioxide transported in a liquefied state of approximately 0.6MPa, -50 ℃.

As such, the carbon dioxide stored and transported as a liquid must stay in the storage tank at a high pressure and a low temperature compared with the surrounding environment, and thus the storage tank can withstand the pressure and the temperature control to maintain the temperature of the storage liquid at a low temperature. Facilities should be in place.

On the other hand, carbon dioxide is no longer able to maintain a liquid state at pressures below the triple point (0.516Mpa, -57.3 ° C), and solidifies to dry ice, which is then vaporized to change into a gaseous state. This is different from the case where the gas cargo stored in the liquid state such as natural gas is kept in the liquid state as it is even if the pressure is lowered.

The pressure drop in the storage tank is mainly caused in the process of distributing liquid carbon dioxide by communicating with the outside through piping materials such as discharging liquid carbon dioxide stored in the storage tank or introducing liquid carbon dioxide into an empty storage tank. .

On the other hand, when liquid carbon dioxide solidifies due to a decrease in internal pressure, dry ice growing on the inner wall of the pipe may block the pipe, making it impossible to distribute carbon dioxide, and even dry ice may break into related equipment by invading delivery pumps or valves. do.

The present invention has been made to solve the above-described problem, an embodiment of the present invention has an object that the liquid carbon dioxide stored in the pressure drop in the storage tank does not cause a phase change.

Specifically, to monitor the pressure change of the storage tank generated during the process of unloading the liquid carbon dioxide to the storage tank, and to block the storage tank and the unloading equipment before the phase change of the liquid carbon dioxide so that the storage tank unloading is made within a stable pressure range Has the purpose.

In order to solve the above problems, the present invention is an internal pressure of the storage tank of the carbon dioxide is equipped with a liquid inlet pipe into which liquid carbon dioxide is introduced, and a liquid outlet pipe to discharge the stored liquid carbon dioxide to the outside is less than a predetermined set pressure. When lowered to the low pressure of the carbon dioxide storage tank, characterized in that to block the flow of liquid carbon dioxide in the liquid inlet pipe or liquid outlet pipe.

The low pressure prevention method may further include a pressure measuring step of measuring a liquid pressure of liquid carbon dioxide contained in the storage tank, a pressure comparing step of comparing the set pressure with the liquid pressure, and when the liquid pressure is equal to or less than the set pressure, It provides a low pressure prevention method of the carbon dioxide storage tank, characterized in that for blocking the liquid inlet pipe or the liquid outflow pipe, if the liquid pressure exceeds the set pressure to perform a pressure measuring step again. do.

On the other hand, the liquid level measurement step of measuring the liquid level of the liquid carbon dioxide filled in the carbon dioxide storage tank equipped with a liquid inflow pipe into which liquid carbon dioxide is introduced, and a liquid outflow pipe for discharging the stored liquid carbon dioxide to the outside, and the liquid liquid level and In preparation for a preset minimum liquid level, the liquid level preparation step of performing the liquid level measuring step again when the liquid level is less than or equal to the minimum predetermined level, and when the liquid level exceeds the minimum level, the storage tank. A pressure measuring step of measuring a liquid pressure of the received liquid carbon dioxide; and a pressure comparing step of performing a liquid level measuring step again when the liquid pressure exceeds the set pressure in contrast to the set pressure and the liquid pressure; The liquid inlet pipe or liquid oil when the liquid pressure is equal to or less than the set pressure; Proposes a method of preventing the low-pressure carbon dioxide storage tank, it characterized in that the lock includes a step to block the flow of liquid carbon dioxide in the pipe.

On the other hand, through the liquid inlet pipe in which the liquid carbon dioxide flows in, and the sensor located at the bottom of the storage tank of the carbon dioxide equipped with a liquid outflow pipe for discharging the stored liquid carbon dioxide to the outside, the liquid carbon dioxide is more than the height of the sensor attached Detecting whether the carbon dioxide is filled with a carbon dioxide detecting step, if the carbon dioxide is not detected in the carbon dioxide detecting step, the carbon dioxide detecting step for performing the carbon dioxide detecting step again, and if the liquid carbon dioxide is detected in the carbon dioxide detecting step. A pressure measuring step of measuring a liquid pressure of the liquid carbon dioxide contained in the storage tank, and comparing the set pressure with the liquid pressure, if the liquid pressure exceeds the set pressure, the second carbon dioxide sensing step is performed again. Contrast stage, The liquid pressure group proposes a method of preventing the low-pressure carbon dioxide storage tank, it characterized in that the case is less than or equal to the set pressure at which includes a locking step to block the flow of the liquid carbon dioxide or liquid inlet pipe liquid outlet pipe.

In addition, the set pressure is proposed to prevent the low pressure of the carbon dioxide storage tank, characterized in that set in consideration of the triple point pressure of the carbon dioxide and the pressure drop of the storage tank generated by the opening and closing of the liquid inlet pipe or the liquid outflow pipe. do.

In addition, the blocking of the liquid outflow pipe suggests a low pressure preventing method of the carbon dioxide storage tank, characterized in that the outlet valve provided in the liquid outflow pipe is made through the closing operation or the operation of the discharge pump for pumping out the liquid carbon dioxide. .

In addition, the blocking of the liquid inlet pipe proposes a low pressure prevention method of the carbon dioxide storage tank, characterized in that the inlet valve provided in the liquid inlet pipe through the closing operation or the operation of the inlet pump for pumping the liquid carbon dioxide inlet. .

According to the low pressure preventing method of the carbon dioxide storage tank according to the embodiment of the present invention as described above, it is possible to prevent the solidification or vaporization of carbon dioxide due to the pressure drop during the unloading operation of the storage tank while storing the liquid carbon dioxide, stable storage tank The operation of the has the effect that becomes possible.

Specifically, the set pressure, which is a criterion for blocking the pressure drop flow path of the storage tank, is set in consideration of the pressure drop value according to the operation of transportation equipment such as the triple point of carbon dioxide and pipes, thereby preventing the pressure drop of the storage tank during the unloading of liquid carbon dioxide. It has the effect of being able to.

In addition, the blocking of each pipe also has the effect of preventing the failure of the pump, including stopping the pump in operation with the lock of the open valve.

On the other hand, since the monitoring of the pressure drop of the storage tank is performed only when sufficient liquid carbon dioxide is filled in the storage tank, it is effective to prevent malfunctions, such as blocking of valves, even when the storage tank is completely emptied by a ship or the like. .

In the method for preventing low pressure of a carbon dioxide storage tank according to the first embodiment of the present invention, in order to prevent a phase change of liquid carbon dioxide due to a pressure drop that may occur during the process of unloading liquid carbon dioxide into the storage tank, a setting preset by a user By stopping the unloading operation when the pressure in the storage tank falls below the pressure, no further liquefied carbon dioxide flows out or flows into the storage tank, thereby preventing further pressure drop.

The stopping of the unloading operation is performed by blocking each pipe into which the liquid carbon dioxide flows in and out, and after the inside of the pipe is sufficiently pressurized, the blocked pipe is opened again to raise the pressure of the storage tank back to the normal range, thereby storing the storage tank. It is to keep the operation stable.

Hereinafter, the function, configuration and operation of the low pressure prevention method of the carbon dioxide storage tank of the present invention through the preferred embodiment of the accompanying drawings will be described in detail.

1 is a block diagram schematically showing a device configuration for a low pressure preventing method of a carbon dioxide storage tank according to a first embodiment of the present invention, Figure 2 is a low pressure preventing method of a carbon dioxide storage tank according to a first embodiment of the present invention Is a flow chart.

An apparatus configuration to which the low pressure prevention method of the carbon dioxide storage tank according to the first embodiment of the present invention is applied will first be described.

The configuration of the storage tank described below and the pipes, valves, and pumps provided in the storage tank are the same in the second and third embodiments described later.

A liquid outlet pipe 11 for discharging the stored liquid carbon dioxide to the outside is connected to the lower portion of the storage tank 1, and a liquid inflow pipe 12 for storing liquid carbon dioxide from the outside is connected to the upper portion of the storage tank 1. It is connected. Although not shown, the storage tank may further include a gas pipe for gaseous carbon dioxide and a gaseous carbon dioxide inlet pipe for introducing gaseous carbon dioxide or discharging a vapor gas (BOG).

At this time, the liquid outlet pipe 11 is provided with an outlet valve 111, the liquid inlet pipe 12 is provided with an inlet valve 121, the outlet valve 111 and the inlet valve 121 is a liquid carbon dioxide It is open at the time of discharge or inflow, and forms a flow path of liquid carbon dioxide, and has a known configuration in which an electrical signal is opened and closed to operate.

On the other hand, the liquid discharge pipe 11 is further provided with a discharge pump 112, the liquid inlet pipe 12 may be further provided with an inlet pump 122. The discharge pump 112 and the inflow pump 122 is to allow the liquid carbon dioxide passing through the liquid outflow pipe 11 or the liquid inflow pipe 12 to be transported under pressure so that the liquid carbon dioxide can be smoothly transferred. It is a fluid pump having a known configuration capable of pumping liquid carbon dioxide. In addition, the discharge pump 112 and the inflow pump 122 receives the tourmaline signal, such as the outlet valve 111 and the inlet valve 121 described above is to control the operation.

In addition, the discharge pump 112 is connected to the liquid discharge pipe 11 in series as shown, or more preferably connected in parallel is configured so that the liquid carbon dioxide discharged through the liquid discharge pipe is discharged immediately without passing through the discharge pump. You may. This serial or parallel connection applies equally to inlet pump 122.

On the other hand, the pressure sensor 21 for measuring the pressure of the stored liquid carbon dioxide is mounted on the bottom or bottom of the side wall of the storage tank (1). At this time, the pressure sensor 21 is capable of measuring the pressure of a fluid containing a liquid or gas, and has a known configuration that can generate the measured pressure as an electrical signal and transmit it to the control unit 2.

A method of preventing low pressure of a carbon dioxide storage tank according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The low pressure prevention method of the carbon dioxide storage tank according to the first embodiment of the present invention is made through a pressure measuring step (s-1), a pressure contrast step (s-2) and a locking step (s-3).

The pressure measuring step (s-1) measures the pressure of the liquid carbon dioxide (hereinafter referred to as 'liquid pressure') received in the storage tank 1 through the pressure sensor 21 as an electrical signal, and the measured liquid pressure is controlled by the controller. Is sent to (2).

On the other hand, the pressure contrast step (s-2) is a step in which the large and small contrast between the set pressure preset by the user in the control unit 2 and the measured liquid pressure.

In this case, the set pressure is set in consideration of the triple point pressure of carbon dioxide and the pressure drop of the storage tank 1 generated in accordance with the opening of the liquid inlet pipe 12 or the liquid outlet pipe 11.

Specifically, the set pressure may be set to a pressure value of 0.516 MPa, which is the triple point pressure of carbon dioxide, plus a pressure drop caused by a liquid inlet pipe, etc. At this time, specific values of the pressure drop may include structural characteristics of the storage tank 1 and liquid. It is determined according to the characteristics of the transport equipment of the liquid carbon dioxide including the length and diameter of the inlet pipe 12 and the liquid outlet pipe 11.

The transport equipment includes the aforementioned outlet valve 111 and the inlet valve 121, the discharge pump 112 and the inlet pump 122, and the pressure drop is selectively opened or simultaneously opened and closed during the unloading process of the liquid carbon dioxide. Opening / closing combination of the valve 111 and the inlet valve 121 and the liquid carbon dioxide flow path secured variously according to the liquid carbon dioxide discharging method such as whether the discharge pump 112 and the inflow pump 122 are connected in parallel or in series Depends on. Therefore, the pressure drop according to the configuration of the transport equipment is usually obtained through the unloading test operation of the liquid carbon dioxide by various flow paths during the initial operation of the storage tank.

Furthermore, the safety pressure can be further increased by adding a safety margin to the set pressure. This stability margin is determined arbitrarily by the user according to the proper operating pressure range of the storage tank.

Therefore, the set pressure is determined to be larger than the pressure at least at the triple point of carbon dioxide, and this set pressure can effectively prevent the pressure drop of the storage tank during the process of unloading the liquid carbon dioxide from the storage tank by considering the pressure drop by the transport equipment. To be able.

On the other hand, the locking step (s-3) blocks the liquid inflow pipe 12 or the liquid outflow pipe 11 when the liquid pressure is less than the set pressure, and again if the liquid pressure exceeds the set pressure. The pressure measuring step (s-1) is performed.

When the liquid pressure is determined to be equal to or lower than the set pressure, the control unit 2 may open or close the liquid inlet pipe 12 or the liquid outflow pipe 11, since the liquid carbon dioxide may be solidified or vaporized in the storage tank 1. By blocking it will prevent any further pressure drop in the storage tank (1).

At this time, the shutoff of the liquid inlet pipe 12 is achieved by generating an electrical signal for the control unit 2 to close the outlet valve and transmitting it to the outlet valve.

In addition, when the discharge pump 112 is provided, the control unit 2 transmits an electrical signal to the discharge pump 112 to stop the operation of the discharge pump 112 together.

In this case, the supply of liquid carbon dioxide flowing into the discharge pump is cut off according to the blocking of the liquid inlet pipe, so that the discharge pump operates in vain to prevent damage.

On the other hand, the blocking of the liquid inlet pipe 12 is made through the closing operation of the inlet valve 121, when the inlet pump 122 is provided by stopping the operation of the inlet pump 122 together. In this case, the controller 2 generates and transmits a tourmaline signal for closing the inlet valve 121 and an electrical signal for stopping the operation of the inlet pump 122, respectively.

On the other hand, Figure 3 is a block diagram schematically showing the device configuration for the low pressure prevention method of the carbon dioxide storage tank according to a second embodiment of the present invention, Figure 4 is a low pressure of the carbon dioxide storage tank according to a second embodiment of the present invention This is a flowchart of the prevention method.

For the low pressure prevention method of the carbon dioxide storage tank according to the second embodiment of the present invention, the configuration of the required storage tank is the same as the configuration of the first embodiment described above except for the following additional configuration, duplicate description Omit.

The storage tank 1 is coupled to a liquid level measurement sensor 22 for measuring the liquid level of the stored liquid carbon dioxide. The liquid level measurement sensor 22 has a configuration known to calculate the liquid level value of the measured liquid carbon dioxide (hereinafter referred to as 'liquid liquid level') as an electric signal and transmit it to the control unit 2.

The second embodiment is configured to monitor the pressure drop of the storage tank only when the liquid tank is filled with liquid carbon dioxide above a certain level, so that when the storage tank 1 is empty and the gas carbon dioxide is filled, the pressure of the storage tank is reduced. Configure not to monitor.

To this end, the second embodiment further passes through the liquid level measuring step (sa), the liquid level preparing step (sb) for measuring the liquid level of liquid carbon dioxide, and then the pressure measuring step (s-1), the pressure preparing step (s-2), and Go through the lock step (s-3).

Level measurement step (s-a) is a step of measuring the liquid level through the liquid level measurement sensor 22 provided in the storage tank, converts it into an electrical signal and transmits it to the control unit (2). At this time, the liquid level measurement sensor 22 can calculate the length from the bottom of the storage tank 1 to the liquid level of liquid carbon dioxide, and has a known configuration.

The liquid level contrasting step (s-b) is a step in which the control unit 2 contrasts the liquid level and the minimum set level previously set by the user, and performs the liquid level measuring step again when the liquid level is below the minimum set level.

At this time, the minimum set liquid level is set to a value of "0" or smaller than that when the liquid carbon dioxide is empty in the storage tank 1 or when a small amount of liquid carbon dioxide is present at the bottom of the storage tank 1. It is preferably set to a value.

In addition, the minimum set liquid level may be set in various ways, such as being defined as the ratio of the liquid liquid level of the remaining liquid carbon dioxide to the liquid level of the liquid carbon dioxide which is filled maximum in the storage tank according to the design value.

In addition, when the liquid level is less than the minimum set level, it may be to perform the level measurement step again with a certain delay time, otherwise it may be configured to be finished from the level measurement step again by the start command of the next user. .

On the other hand, when the liquid level exceeds the minimum set level, since the liquid carbon dioxide is sufficiently filled in the storage tank, a problem may occur due to the pressure drop of the storage tank, so that the control unit measures the pressure as in the first embodiment. Steps, pressure preparation and locking.

At this time, since the pressure measuring step (s-1) and the locking step (s-3) are the same as in the above-described first embodiment, redundant description thereof will be omitted.

In the pressure comparing step (s-2), in contrast to the set pressure and the liquid pressure obtained through the pressure measuring step (s-1), when the liquid pressure exceeds the set pressure, the liquid level measuring step sa is performed again. If the liquid pressure is less than the set pressure to perform the locking step (s-3).

In this case, when the liquid pressure exceeds the set pressure and is in a normal state, the flow returns to the liquid level measurement step (sa), and first checks whether the liquid carbon dioxide has escaped into the storage tank by unloading the liquid carbon dioxide, and then stores the liquid. The pressure drop in the tank will be monitored.

This second embodiment is to prepare for the case where the storage tank is empty, which is preferably applied to the storage tank of the ship transporting carbon dioxide. In particular, in a ship carrying a combination of carbon dioxide and other liquid cargo, such as liquefied natural gas, it is suitable for a process in which the liquid cargo in the storage tank is completely empty and then replaced with another liquid cargo. Furthermore, since the operation of the control unit for monitoring the pressure drop is mainly used in the transport of liquid carbon dioxide, it is preferable to further include a switch means for turning on / off the operation of the control unit in the type of liquid cargo.

On the other hand, Figure 5 is a schematic block diagram showing the device configuration for the low pressure prevention method of the carbon dioxide storage tank according to a third embodiment of the present invention, Figure 6 is a low pressure of the carbon dioxide storage tank according to a third embodiment of the present invention This is a flowchart of the prevention method.

According to the third embodiment of the present invention, whether or not the storage tank pressure drop is sensed according to whether the storage tank is filled with a liquid carbon dioxide above a certain level as in the above-described second embodiment.

To this end, the bottom of the storage tank 1 is provided with a detection sensor 23 that can detect the presence of liquid.

At this time, the detection sensor 23 can detect whether the liquid carbon dioxide is filled up to the installed height, and has a known configuration that can generate the presence of the liquid carbon dioxide as an electrical signal.

The installation height of the detection sensor 23 is installed higher than the installation height of the pressure sensor 21, and is configured to measure the pressure of the liquid carbon dioxide when it is detected by the detection sensor 23 that liquid carbon dioxide is present.

In the third embodiment having such a configuration, after the carbon dioxide detection step s-a and the carbon dioxide detection step s-b, the liquid carbon dioxide is detected by the sensor, the pressure measurement step s-1, and the pressure It is to perform the step (s-2) and the lock step (s-3).

Carbon dioxide detection step (s-a) is a step of detecting whether the liquid carbon dioxide by the detection sensor 23 generates an electrical signal and transmits it to the control unit (2).

At this time, the presence of the liquid carbon dioxide has a meaning of detecting whether the liquid level of the liquid carbon dioxide is formed above the height of the sensor installed. Therefore, the installation height of the detection sensor 23 is installed in the storage tank according to the height corresponding to the minimum liquid level of the liquid carbon dioxide does not matter the vaporization or solidification of the liquid carbon dioxide according to the operating conditions of each storage tank.

On the other hand, if the carbon dioxide detection step (s-b) is not detected through the electrical signal received from the sensor 23 in the control unit 2, the carbon dioxide detection step (s-a) is performed again. It's a step.

In this case, a predetermined delay may be required before the carbon dioxide detection step is performed, or the carbon dioxide detection step may be performed again by receiving a restart command of the user.

On the other hand, if the liquid carbon dioxide is detected in the carbon dioxide detection step (s-b), since the liquid carbon dioxide is filled in the storage tank, the pressure measurement step (s-1), pressure contrast step (s-2) and the locking step (s) -3).

At this time, since the pressure measuring step (s-1) and the locking step (s-3) are the same as in the above-described first embodiment, redundant description thereof will be omitted.

The pressure comparison step (s-2) is a step of performing the carbon dioxide detection step (s-a) again when the liquid pressure exceeds the set pressure in preparation for the set pressure and the liquid pressure.

In this case, when the liquid pressure exceeds the set pressure and is in the normal storage tank state, the process returns to the carbon dioxide detecting step (s-a) again, and the liquid carbon dioxide is discharged to the storage tank by the unloading operation so that the liquid carbon dioxide is stored in the storage tank. It will again check if it is detected and then monitor the pressure drop in the storage tank.

This third embodiment is to prepare for the case where the storage tank is emptied like the second embodiment, it is preferably applied to the storage tank of the ship transporting carbon dioxide.

Furthermore, by installing the sensor and the liquid level sensor together, it can be configured to improve the operation reliability in preparation for the failure of any one sensor.

1 is a block diagram schematically showing a device configuration for a low pressure prevention method of a carbon dioxide storage tank according to a first embodiment of the present invention.

Figure 2 is a flow chart of a low pressure prevention method of the carbon dioxide storage tank according to the first embodiment of the present invention.

Figure 3 is a block diagram schematically showing the device configuration for the low pressure prevention method of the carbon dioxide storage tank according to the second embodiment of the present invention.

4 is a flowchart of a low pressure preventing method of a carbon dioxide storage tank according to a second embodiment of the present invention.

Figure 5 is a block diagram schematically showing the device configuration for the low pressure prevention method of the carbon dioxide storage tank according to the third embodiment of the present invention.

6 is a flowchart of a low pressure preventing method of a carbon dioxide storage tank according to a third embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: storage tank

11 liquid discharge pipe 111 outlet valve 112 discharge pump

12: liquid inlet pipe 121: inlet valve 122: inlet pump

2: control unit

21 pressure sensor 22 liquid level measurement sensor 23 detection sensor

Claims (7)

When the internal pressure of the carbon dioxide storage tank 1 equipped with the liquid inflow pipe 12 into which the liquid carbon dioxide is introduced and the liquid outflow pipe 11 for discharging the stored liquid carbon dioxide to the outside is lowered below a predetermined set pressure. The low pressure preventing method of the carbon dioxide storage tank, characterized in that to block the liquid carbon dioxide flow of the liquid inlet pipe (12) or the liquid outlet pipe (11). In claim 1, The low pressure prevention method A pressure measuring step (s-1) of measuring the liquid pressure of the liquid carbon dioxide contained in the storage tank (1); A pressure comparison step of comparing the set pressure with the liquid pressure (s-2); When the liquid pressure is less than or equal to the set pressure, the liquid inflow pipe 12 or the liquid outflow pipe 11 is blocked, and when the liquid pressure exceeds the set pressure, the pressure measuring step (s-1) is performed again. Locking step (s-3) to perform; low pressure prevention method of the carbon dioxide storage tank comprising a. Liquid level for measuring the liquid level which is the liquid level of the liquid carbon dioxide filled in the carbon dioxide storage tank (1) equipped with the liquid inlet pipe 12 into which the liquid carbon dioxide flows, and the liquid outlet pipe 11 for discharging the stored liquid carbon dioxide to the outside. Measuring step (sa); A liquid level contrast step (s-b) for performing the liquid level measuring step (s-a) again when the liquid level is less than or equal to the minimum set level that is set to the wheat level in contrast to the liquid level and the predetermined minimum set level; A pressure measuring step (s-1) of measuring the liquid pressure of the liquid carbon dioxide contained in the storage tank (1) when the liquid level exceeds the minimum set level; A pressure comparison step (s-2) for performing the liquid level measurement step (s-a) again when the liquid pressure exceeds the set pressure, in contrast to the set pressure and the liquid pressure; A locking step (s-3) of blocking the liquid carbon dioxide flow of the liquid inflow pipe 12 or the liquid outflow pipe 11 when the liquid pressure is less than or equal to the set pressure. How to prevent low pressure. The liquid inlet pipe 12 into which the liquid carbon dioxide flows in, and the sensor 23 located at the bottom of the carbon dioxide storage tank 1 having the liquid outlet pipe 11 for discharging the stored liquid carbon dioxide to the outside, the liquid A carbon dioxide detecting step of detecting whether carbon dioxide is filled up to a height at which the sensor 23 is installed; If the liquid carbon dioxide is not detected in the carbon dioxide detection step (s-a), the carbon dioxide detection step (s-b) to perform the carbon dioxide detection step (s-a) again; A pressure measuring step (s-1) of measuring the liquid pressure of the liquid carbon dioxide contained in the storage tank (1) when the liquid carbon dioxide is detected in the carbon dioxide detecting step (s-b); A pressure contrast step of performing a carbon dioxide detection step (s-a) again when the liquid pressure exceeds the set pressure in contrast to a preset set pressure and the liquid pressure; A locking step (s-3) of blocking the liquid carbon dioxide flow of the liquid inflow pipe 12 or the liquid outflow pipe 11 when the liquid pressure is less than or equal to the set pressure. How to prevent low pressure. The method according to any one of claims 1 to 4, The set pressure is Prevention of low pressure of the carbon dioxide storage tank, characterized in that it is set in consideration of the triple point pressure of the carbon dioxide and the pressure drop of the storage tank (1) generated in accordance with the opening and closing of the liquid inlet pipe 12 or the liquid outflow pipe (11). Way. In claim 5, Blocking of the liquid outflow pipe (11) Method for preventing the low pressure of the carbon dioxide storage tank, characterized in that the outlet valve 111 provided in the liquid outflow pipe (11) through the closing operation or the operation of the discharge pump (112) for pumping out the liquid carbon dioxide. In claim 5, Blocking of the liquid inlet pipe 12 is Method for preventing the low pressure of the carbon dioxide storage tank, characterized in that the inlet valve 121 provided in the liquid inlet pipe (12) through the closing operation or the operation of the inlet pump (122) for pumping the liquid carbon dioxide inlet.

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