JP2009047234A - Storage / discharge device for liquefied gas and method of operating the same - Google Patents

Abstract

Disclosed is a storage / dispensing device for liquefied gas that does not require a pressurized evaporator and therefore can be operated at a low cost, and an operation method thereof.
An apparatus includes a vacuum adiabatic storage tank for a liquefied gas, a vaporizer, and a vacuum degree adjusting device. The vacuum degree adjusting device 40 includes a gas supply means for supplying N ₂ gas between the storage tank inner and outer tanks 14 of the storage tank 10, a vacuum pump means 44 for evacuating the storage tank inner and outer tanks 14, and a pressure for detecting the pressure of the storage tank 10. Detecting means 47, and when the pressure of the gas phase 15 of the storage tank 10 is lower than a predetermined value, N ₂ gas is supplied between the storage tank inner and outer tanks 14 based on a signal from the pressure detection means 47 and between the storage tank inner and outer tanks. 14 is reduced, the amount of heat input is increased, and vaporization of the liquefied gas LG is promoted. When the pressure of the gas phase 15 becomes higher than a predetermined pressure, the vacuum pump means 44 is operated to evacuate the tank between the storage tank and the external tank, and the degree of vacuum between the storage tank and the external tank is increased to increase the amount of heat input. Reduce.
[Selection] Figure 2

Description

  The present invention relates to a storage / dispensing device for liquefied gas, for example, for storing liquefied gas such as LNG and LPG and discharging the liquefied gas to a consumer device side, and an operating method thereof.

  Liquefied gases such as LNG and LPG are environmentally friendly energy sources and are desirably used more widely as industrial energy. When the liquefied gas is used as industrial energy, the liquefied gas is stored in a vacuum adiabatic storage tank, and then discharged from the use side (consumer) such as a furnace or a gas turbine. In order to secure the required pressure on the consumer equipment side, the current vacuum insulation type storage tank is equipped with a pressurized evaporator as an auxiliary facility, and the gas evaporated in the vacuum insulation type storage tank is evaporated and vaporized by the pressurized evaporator. In general, an operation system that pressurizes the liquid level in the storage tank and ensures a required discharge pressure.

  FIG. 3 shows an example of this, and the vacuum adiabatic storage tank 10 receives the liquefied gas LG by a lorry vehicle. The vacuum heat insulating storage tank 10 includes an inner tank 11 and an outer tank 12, and a heat insulating material 13 such as perlite is filled between the inner tank 11 and the outer tank 12 and is evacuated to a high degree of vacuum. The liquefied gas LG in the vacuum adiabatic storage tank 10 is discharged to the vaporizer 20, and gasified by passing through the vaporizer 20 is supplied to the consumer equipment side.

  A part of the liquefied gas LG in the vacuum adiabatic storage tank 10 is sent to the pressure evaporator 30, and the vaporized and vaporized gas passes through the pressure regulating valve 31 to the gas phase portion in the vacuum adiabatic storage tank 10. It is sent. For example, when the required pressure on the consumer device side is 0.2 MPa, the pressure adjustment valve 31 is set to 0.3 MPa as a set pressure and a detection signal from the pressure detection means 32 that can detect the pressure in the vacuum adiabatic storage tank 10 as a control signal. The opening and closing control is performed, and the operation of the apparatus is performed so that a pressure of 0.3 MPa or more is established on the liquid surface of the vacuum heat insulating storage tank 10.

  The operation system of this equipment is accompanied by the act of pressurizing the liquid level of the liquefied gas LG, and the act of pressurizing the liquid level corresponds to the manufacturing action under the High Pressure Gas Safety Law. Is required to have qualified personnel (security personnel). Usually, the storage and discharge equipment for liquefied gas as described above is normally operated continuously for 24 hours. For this reason, a plurality of qualified persons (security personnel) are required. This inevitably poses an obstacle to the widespread introduction and promotion of liquefied gas as industrial energy, both in terms of securing human resources and increasing operating costs.

  Patent Document 1 discloses a vacuum tank that is maintained at a predetermined vacuum pressure by a vacuum pump, and a vacuum insulation space between the vacuum tank and a vacuum insulator, as a vacuum insulation container that can maintain desired heat insulation performance. And an opening / closing valve interposed in the communication path and an opening valve for opening the vacuum insulation space to the atmosphere. By appropriately opening and closing the on-off valve and an open valve that opens the vacuum heat insulation space to the atmosphere, a vacuum heat insulation container capable of maintaining the desired heat insulation performance by adjusting the thermal conductivity of the vacuum heat insulation space is obtained. It is done.

JP-A-6-74391

  As described above, liquefied gases such as LNG and LPG are environmentally friendly energy sources, and it is desired to use them more widely as industrial energy. Therefore, it is necessary to secure qualified personnel (security personnel), which delays the promotion of introduction of liquefied gas in terms of both securing personnel and costs. It is a factor.

  This invention is made | formed in view of said situation, and makes it a subject to disclose the storage-dispensing apparatus for liquefied gas which can be drive | operated at lower cost, and its operating method.

  In order to solve the above problems, the present inventors have improved the technique for adjusting the thermal conductivity of the vacuum heat insulation space by controlling the degree of vacuum of the vacuum heat insulation space described in Patent Document 1 to improve the liquefied gas. It has been found out that the problem can be solved by adopting the storage / dispensing apparatus for use, and has led to the present invention.

  That is, the invention according to claim 1 includes at least a vacuum adiabatic storage tank for liquefied gas, and a vaporizer that vaporizes and vaporizes the liquefied gas discharged from the vacuum adiabatic storage tank toward a consumer device. A liquefied gas storage / dispensing device, wherein the device further includes a vacuum degree adjusting device, and the vacuum degree adjusting device stores the liquefied gas between the inner and outer tanks of the storage tank constituting the vacuum adiabatic storage tank. Gas supply means for supplying a gas whose liquefaction temperature is lower than the temperature of the tank, vacuum pump means for evacuating the inside and outside of the storage tank, pressure detection means for detecting the pressure in the vacuum adiabatic storage tank, and pressure detection means And at least switching means for switching between supplying gas from the gas supply means between the inner and outer tanks of the storage tank or evacuating the inner and outer tanks by the vacuum pump means based on the signal. And butterflies.

  The invention according to claim 2 includes at least a vacuum adiabatic storage tank for liquefied gas, and a vaporizer that vaporizes and vaporizes the liquefied gas discharged from the vacuum adiabatic storage tank toward a consumer device. A method for operating a storage / dispensing device for liquefied gas, wherein the pressure in the vacuum insulation tank is lower than a first set pressure set on the basis of the required pressure on the consuming equipment side. The step of supplying a gas whose liquefaction temperature is lower than the temperature of the liquefied gas to be stored between the inner and outer tanks constituting the storage tank and lowering the degree of vacuum between the inner and outer tanks, and the pressure in the vacuum insulated tank Dispensing by repeatedly evacuating the storage tank inside and outside the tank and increasing the degree of vacuum between the storage tank and the outside tank when the second set pressure, which is higher than the first set pressure, is exceeded Ensuring necessary supply pressure And wherein the Rukoto.

  In the apparatus according to the present invention and the operation method thereof, the amount of vaporization of the stored liquefied gas is adjusted by changing the heat insulation performance by controlling the degree of vacuum between the inner and outer tanks of the vacuum heat insulation type storage tank, thereby In order to maintain the required supply pressure during the dispensing. That is, in the present invention, the pressure in the storage tank can be increased in the storage tank body, which has been conventionally performed by the pressure evaporator for the purpose of securing the necessary pressure on the consumer device side, and thus the pressure evaporator is omitted. be able to. As a result, since the operation of the facility does not correspond to the manufacturing action under the High Pressure Gas Safety Law, the resident of qualified personnel is not required, and the operator who manages the operation of the facility can greatly reduce the labor cost. Thereby, the further promotion introduction effect to industrial use of liquefied gas, such as environmentally friendly LNG, can be anticipated. In addition, since a pressurized evaporator is not required and equipment that passes through liquefied gas such as LNG is reduced, an effect of reducing the burden on the operator can be expected in terms of maintenance.

The gas used in the present invention is not particularly limited to a gas having a liquefaction temperature lower than the temperature of the liquefied gas to be stored. However, while the LNG temperature is -162 ° C, the liquefaction temperature is as low as -196 ° C. An active N ₂ gas is particularly preferred. In the case of a gas whose liquefaction temperature is higher than the temperature of the liquefied gas stored, for example, air containing moisture, the water is frozen by the cold heat of the liquefied gas at the moment when it is supplied between the inner and outer tanks. Not suitable. When air is used, it is necessary to use almost completely dry air.

  In the storage and discharge device for liquefied gas according to the present invention, the degree of vacuum between the inner and outer storage tanks of the vacuum adiabatic storage tank is controlled so as to obtain a supply pressure required for discharging. As a result, the pressurized evaporator that was installed for the purpose of pressurizing the liquid level of the storage tank and increasing the internal pressure of the storage tank can be omitted, and there is no need to have a qualified person resident under the High Pressure Gas Safety Law in the operation of the equipment. It becomes. Therefore, the operating cost of the facility can be greatly reduced. In addition, by reducing the number of devices that pass through the liquefied gas such as LNG, it is possible to expect a burden reducing effect in terms of maintenance.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a block diagram showing an example of a storage and discharge device for liquefied gas according to the present invention, and FIG. 2 is a block diagram showing an example of the vacuum degree adjusting device.

  As shown in FIG. 1, in the storage / dispensing device 1 for liquefied gas according to the present invention, as described with reference to FIG. 3, the vacuum adiabatic storage tank 10 receives the liquefied gas LG by a lorry vehicle and is necessary. Sometimes, the liquefied gas LG in the vacuum adiabatic storage tank 10 is discharged toward the vaporizer 20. By passing through the vaporizer 20, the liquefied gas is gasified and supplied to the consumer equipment side.

  The configuration of the vacuum heat insulating storage tank 10 is substantially the same as that of the conventional one, and includes an inner tank 11 and an outer tank 12, and a heat insulating material 13 such as pearlite is filled therebetween. However, in the conventional vacuum adiabatic storage tank, the degree of vacuum between the inner and outer tanks is evacuated in advance and is always maintained at a high degree of vacuum, but in the vacuum adiabatic storage tank 10 according to the present invention, the operation of the apparatus 1 is performed. The vacuum degree between the storage tank inner and outer tanks 14 is changed by the operation of the vacuum degree adjusting device 40.

Hereinafter, the configuration and operation of the vacuum degree adjusting device 40 will be described. As shown in FIG. 2, the vacuum degree adjusting device 40 includes an N ₂ gas cylinder 41 that is a gas whose liquefaction temperature is lower than the temperature of the liquefied gas (for example, LNG) to be stored, and the N ₂ gas in the N ₂ gas cylinder 41 Passes through the first on-off valve 42 and the pipe 43 and is supplied into the storage tank 14. Further, the vacuum degree adjusting device 40 includes a vacuum pump 44 and is connected to the pipe line 43 on the downstream side of the first on-off valve 42 through a buffer tank 45 and a second on-off valve 46. The first open / close valve 42 is a normally closed valve, and includes a valve open / close mechanism 42a that receives a pressure signal as an input signal. The second opening / closing valve 46 is also a normally closed valve, and is also provided with a valve opening / closing mechanism 46a using a pressure signal as an input signal.

  The vacuum degree adjusting device 40 further includes a pressure sensor 47 as pressure detecting means. The pressure sensor 47 detects the pressure in the gas phase 15 of the vacuum adiabatic storage tank 10, and outputs the pressure signal to the valve opening / closing mechanism 42a of the first opening / closing valve 42 and the valve opening / closing mechanism 46a of the second opening / closing valve 46, and , Respectively, to the drive mechanism of the vacuum pump 44. The valve opening / closing mechanism 42a of the first opening / closing valve 42 opens the first opening / closing valve 42 when the pressure signal sent is less than the first set pressure p1. The valve opening / closing mechanism 46a of the second opening / closing valve 46 has the second opening / closing valve 46 when the pressure signal sent is equal to or higher than the second set pressure p2, which is higher than the first set pressure p1. open. The drive mechanism of the vacuum pump 44 drives the vacuum pump 44 when the pressure signal sent is equal to or higher than the second set pressure p2.

  Next, an operation mode of the vacuum degree adjusting device 40 will be described. First, the control mechanism (not shown) operates the vacuum pump 44 with the first on-off valve 42 closed and the second on-off valve 46 open to evacuate the storage tank inside / outside tank 14, The degree of vacuum between 14 is set to a preset value. In this state, an operation of receiving the LNG of the lorry vehicle into the vacuum adiabatic storage tank 10 is performed. After receiving a predetermined amount of LNG, between the inner and outer tanks 14 so that the pressure of the gas phase 15 of the vacuum adiabatic storage tank 10 becomes a pressure pa between the first set pressure p1 and the second set pressure p2. Adjust the degree of vacuum. In this example, it is assumed that the required pressure for supplying gas from the vaporizer 20 to the consumer device is 0.2 MPa, the first set pressure p1 is 0.3 MPa, and the second set pressure p2 is 0.00. Assuming 4 MPa, the following will be described.

  LNG in the vacuum heat insulating storage tank 10 is dispensed to the vaporizer 20 in response to a request from the consumer equipment side. Accordingly, the pressure in the vacuum adiabatic storage tank 10 decreases. Or the pressure in the vacuum heat insulation type storage tank 10 may fall by the factor resulting from the external environment or the apparatus itself in which the vacuum heat insulation type storage tank 10 is installed. When the pressure in the vacuum adiabatic storage tank 10 (dispensing pressure) is lower than 0.3 MPa, which is the first set pressure p1, there is an adverse effect on the consumer equipment.

The pressure in the vacuum adiabatic storage tank 10 is detected by a pressure sensor 47, and the signal is sent to the valve opening / closing mechanisms 44a and 46a of the first and second opening / closing valves 42 and 46 and the vacuum pump 44. When the sensor 47 transmits a pressure signal less than 0.3 MPa, which is the set pressure p1, the valve opening / closing mechanism 42a opens the first opening / closing valve 42. As a result, the N ₂ gas in the N ₂ gas cylinder 41 passes through the first on-off valve 42 and the conduit 43 and is supplied into the storage tank inner / outer tank 14, and the degree of vacuum in the storage tank inner / outer tank 14 decreases. To do. Thereby, the amount of heat input between the storage tank inner and outer tanks 14 increases, and the vaporization of stored LNG is promoted.

  As the vaporization of LNG proceeds, the pressure in the gas phase part 15 in the vacuum adiabatic storage tank 10 increases. When the pressure of the gas phase section 15 becomes 0.4 MPa or more, which is the second set pressure p2, the vacuum pump 44 is activated by the pressure signal sent from the pressure sensor 47, and the valve opening / closing mechanism 46a opens the second on-off valve 46. Simultaneously with the opening of the second on-off valve 46, the first on-off valve 42 is closed.

As a result, the supply of N ₂ gas between the storage tank inner and outer tanks 14 is stopped, and at the same time, evacuation between the storage tank inner and outer tanks 14 progresses, and the degree of vacuum gradually increases. Thereby, the amount of heat input between the storage tank inner and outer tanks 14 is reduced, and vaporization of stored LNG is suppressed. Then, when the pressure in the gas phase section 15 becomes any one of the pressure values pa (0.3 to 0.4 MPa) between the first set pressure p1 and the second set pressure p2, it is illustrated. The control mechanism that does not sends a stop command to the vacuum pump 44 and a command to close the second on-off valve 46 to the valve opening / closing mechanism 46a.

  As described above, in the storage and discharge device for liquefied gas and the operation method thereof according to the present invention, it is possible to use a consumer device to discharge from the vacuum insulated storage tank for liquefied gas without using a conventional pressurized evaporator. This can be carried out continuously while maintaining the required pressure on the side. Therefore, the operation cost and maintenance cost of equipment can be greatly reduced.

The block diagram which shows an example of the storage-dispensing apparatus for liquefied gas by this invention. The block diagram which shows an example of the vacuum degree adjustment apparatus in the apparatus shown in FIG. The block diagram explaining the storage / dispensing apparatus for the conventional liquefied gas.

Explanation of symbols

LG ... liquefied gas, 1 ... storage / dispensing device for liquefied gas, 10 ... vacuum adiabatic storage tank, 11 ... inner tank, 12 ... outer tank, 13 ... heat insulating material, 14 ... between tank inner and outer tanks, 15 ... gas phase, 20 ... vaporizer, 40 ... vacuum regulator, 41 ... _{N 2} gas cylinder, 42 ... first on-off valve, 42a ... valve opening-closing mechanism, 44 ... vacuum pump, 45 ... buffer tank, 46 ... second on-off valve, 46a ... valve opening / closing mechanism, 47 ... pressure sensor as pressure detecting means, p1 ... first set pressure, p2 ... second set pressure, pa ... pressure between the first set pressure and the second set pressure

Claims (2)

A storage and discharge device for liquefied gas, comprising at least a vacuum adiabatic storage tank for liquefied gas, and a vaporizer that vaporizes the liquefied gas discharged from the vacuum adiabatic storage tank and sends the vaporized gas toward a consumer device. There,
The apparatus further includes a vacuum degree adjusting device, and the vacuum degree adjusting device supplies a gas having a lower liquefaction temperature than the temperature of the liquefied gas to be stored between the inner and outer tanks constituting the vacuum adiabatic storage tank. Based on the signal from the supply means, the vacuum pump means for evacuating the inside and outside of the storage tank, the pressure detection means for detecting the pressure in the vacuum adiabatic storage tank, and the gas supply means between the inside and outside tanks of the storage tank A storage / dispensing device for liquefied gas, comprising at least switching means for switching between supplying gas or evacuating the storage tank inside and outside by a vacuum pump means. A storage / dispensing device for liquefied gas comprising at least a vacuum adiabatic storage tank for liquefied gas, and a vaporizer that vaporizes the liquefied gas discharged from the vacuum adiabatic storage tank and sends the vaporized gas toward a consumer device. Driving method,
When the pressure in the vacuum adiabatic storage tank becomes lower than the first set pressure set on the basis of the required pressure on the consumer device side, the liquefied gas to be stored between the inner and outer tanks constituting the vacuum adiabatic storage tank A step of supplying a gas having a liquefaction temperature lower than the temperature to lower the degree of vacuum between the inner and outer storage tanks, and a second set pressure at which the pressure in the vacuum adiabatic storage tank is higher than the first set pressure For liquefied gas, the required supply pressure at the time of discharge is ensured by repeating the process of increasing the degree of vacuum between the storage tank inside and outside tanks by evacuating the storage tank inside and outside the tank. Operation method of storage / dispensing apparatus.

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