JP2006022854A - Large-sized cryogenic liquefied gas reservoir - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large-sized cryogenic liquefied gas reservoir enabling a simple filling operation, reduced in the cost of a facility, enabling the easy control of flow, and preventing BOG (boil-off gas) from producing. <P>SOLUTION: This large-sized cryogenic liquefied gas reservoir comprises a plurality of inner reservoirs 2 to 5 and a cold insulating reservoir 1 storing the inner reservoirs 2 to 5. The inner reservoir 2 is an inner reservoir 2 used exclusively for filling a cryogenic liquefied gas from a lorry 6 into the inner reservoir 2 by utilizing a difference in operating pressure between the lorry 6 and the inner reservoir 2. A feed pump 7 for feeding and filling the cryogenic liquefied gas taken out from the exclusively used inner reservoir 2 to those reservoirs 3 to 5 other than the exclusively used inner reservoir 2 is installed in an LNG retrieval pipe 10 extended from the exclusively used inner reservoir 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a large cryogenic liquefied gas storage tank for storing a cryogenic liquefied gas such as LNG (liquefied natural gas).

  Conventionally, in an adiabatic storage tank for storing a cryogenic liquefied gas such as LNG installed in an LNG satellite facility or the like, when the LNG or the like is filled from lorry due to emptiness, the operating pressure of the lorry and the insulation storage tank Differential pressure filling is performed using the differential pressure with the operating pressure. Moreover, when supplying LNG etc. which are stored in an adiabatic storage tank for industrial use, it is higher than the operating pressure of Raleigh (operating pressure of about 0.55 MPa is commonly used in the case of differential pressure filling according to the law). It may be necessary to supply at a pressure (medium pressure of about 0.6 MPa).

  Therefore, for example, as shown in FIG. 3, a plurality of (two in FIG. 3) heat insulation storage tanks 21 and 22 constituted by inner and outer double tanks (not shown) are installed. The BOG (boil-off gas) discharge pipes 23 and 24 are extended from the top of 22, and the LNG take-out pipes 25 and 26 are extended from the bottom, and both the LNG take-out pipes 25 and 26 are connected to the intermediate pressure gas supply pipe 28 via the connecting pipe 27. And at the time of filling, first, BOG is discharged from the emptied heat insulation storage tank 21 (22) to depressurize (from about 0.7 MPa to about 0.3 MPa), and then the lorry After the LNG is differentially charged from the LNG storage tank 30a mounted on the tank 30a into the heat-insulated storage tank 21 (22) that has been depressurized by the filling line 31, the pressure-increasing means (not shown) provided in the heat-insulated storage tank 21 (22). Heat storage tank 21 (22) in pressurized and so as to boost up to approximately 0.7 MPa. At the time of supply to the consumer side, the on-off valves 25a and 26a provided on both LNG take-out pipes 25 and 26 and the pressure reducing valves 28a and 29a provided on both gas supply pipes 28 and 29 are operated to provide an intermediate pressure gas supply pipe. A medium pressure LNG of about 28 to 0.6 MPa is supplied to the consumer side, and a low pressure LNG of about 0.15 MPa is supplied to the consumer side from the low pressure gas supply pipe 29. In the figure, 23a and 24a are on-off valves provided on the BOG discharge pipes 23 and 24, and 31a and 31b are on-off valves provided on the filling line 31.

  Further, as shown in FIG. 4, a supply pump 33 is provided in the LNG take-out pipe 25, and a downstream portion of the supply pump 33 and the top of the heat insulation storage tank 21 are connected by a bypass pipe 34 with a flow rate adjusting valve 34a. , LNG is filled into the heat insulation storage tank 21 (the operation pressure is about 0.3 MPa) from the lorry 30 (the operation pressure is about 0.55 MPa) into the heat insulation storage tank 21 that has been emptied. In some cases, the gas is pumped up by the supply pump 33 and pressurized to about 0.7 MPa, and then supplied to the intermediate pressure gas supply pipe 28 and the low pressure gas supply pipe 29. In this case, in order to secure the minimum flow of the supply pump 33, when the flow rate of the LNG take-out pipe 25 decreases, this is detected by the flow rate indicating controller 35, and the flow rate adjusting valve 34a is operated, and the LNG take-out pipe is The LNG passing through the inside 25 is returned to the heat insulating storage tank 21 via the bypass pipe 34.

  However, in the case shown in FIG. 3, since the depressurization work, the differential pressure filling work, and the pressurizing work must be performed at the time of filling, the work becomes complicated when the filling is performed frequently. In addition, when BOG is discharged from the heat-insulating storage tanks 21 and 22 to the atmosphere at the time of depressurization, there is a problem of promoting global warming, so it is necessary to reuse it, and the equipment for that purpose is expensive, and heat insulation When the storage tanks 21 and 22 are large, the amount of BOG discharged becomes large, so the scale of the equipment needs to be increased and the cost is further increased. Further, in the case shown in FIG. 4, in order to cope with a change in the usage amount of the consumer and a flow rate restriction due to the minimum flow, the flow rate control valve 34 a must be adjusted to control the flow rate, which is complicated. Moreover, when the LNG is returned to the heat insulating storage tank 21 via the bypass pipe 34, the LNG is heated by its mechanical energy when passing through the supply pump 33, or is heated by external intrusion heat when passing through the bypass pipe 34. As a result, BOG occurs.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a large cryogenic liquefied gas storage tank in which filling work is simple, equipment is inexpensive, flow rate control is simple, and BOG is not generated. And

  In order to achieve the above object, the large cryogenic liquefied gas storage tank of the present invention comprises a plurality of inner tanks for filling the cryogenic liquefied gas and a cold storage tank for accommodating the plurality of inner tanks. A large cryogenic liquefied gas storage tank, where one inner tank uses the differential pressure between the tank internal pressure and the internal tank internal pressure to store the cryogenic liquefied gas contained in the tank equipped with the lorry. The cryogenic liquefied gas extraction pipe is extended from the dedicated inner tank to an inner tank other than the dedicated inner tank, and the cryogenic liquefied gas extraction pipe is connected to the inner tank from the dedicated inner tank. A configuration is adopted in which a feed pump is provided for feeding and filling the extracted cryogenic liquefied gas to an inner tank other than the dedicated inner tank.

  That is, the large cryogenic liquefied gas storage tank of the present invention has one receiving-only inner tank that is used to fill the cryogenic liquefied gas supplied from the lorry, and only in this dedicated inner tank. The cryogenic liquefied gas contained in the tank mounted on the lorry is filled using the differential pressure between the tank internal pressure (ie, the operating pressure of the lorry) and the internal tank internal pressure (ie, the internal tank operating pressure). I have to. In this differential pressure filling, the inner tank internal pressure is lower than the tank internal pressure. Therefore, a feed pump is provided in the cryogenic liquefied gas take-out pipe extending from the dedicated inner tank, and the cryogenic liquefied gas taken out from the dedicated inner tank is sent to the inner tank other than the dedicated inner tank by the feed pump. It is sent to and filled. Thus, in the large cryogenic liquefied gas storage tank of the present invention, since the internal pressure of the dedicated inner tank is set lower than the internal pressure of the tank equipped with the lorry, the cryogenic liquefied gas is supplied from the lorry to the dedicated inner tank. In the case of filling in, it is not necessary to perform depressurization work before filling and pressurization work after filling for the dedicated inner tank, and the work for filling is simplified. In addition, since the depressurization operation is not performed, BOG does not occur, and it is not necessary to provide facilities for reusing BOG, and the cost is reduced. Moreover, since the cryogenic liquefied gas is merely transferred between the dedicated inner tank and the inner tank other than the dedicated inner tank by the feed pump, the flow rate control of the feed pump and the like is simplified. . In addition, a large amount of the cryogenic liquefied gas is filled in the dedicated inner tank, and when the cryogenic liquefied gas is reduced by a predetermined amount in the inner tank other than the dedicated inner tank, the feed pump is driven each time the cryogenic liquefied gas is reduced. By replenishing the low-temperature liquefied gas, there is no concern about the minimum flow, and the occurrence of BOG that has occurred when using the minimum flow in the conventional example is eliminated. And since the internal tank internal pressure of internal tanks other than the said exclusive internal tank can be set for every various supply conditions, even if there are several types of supply pressure, it is not necessary to have several types of feed pumps. Moreover, since the plurality of inner tanks are housed in the cold storage tank, the inside is kept cold in the cold storage tank, and a storage tank filled with the cryogenic liquefied gas can be used that is constituted only by the inner tank. It is possible (that is, it is not necessary to provide an outer tank separately for each inner tank to make an inner / outer double tank), and the installation space for the large cryogenic liquefied gas storage tank can be reduced accordingly. In addition, since the plurality of inner tanks are covered with the cold storage tank, the ratio of the outer surface area to the total storage amount is reduced, and the evaporation amount per unit storage amount is reduced.

  Further, if the inner tank other than the dedicated inner tank has a pressure increasing means for increasing the internal pressure, the internal pressure of the inner tank other than the dedicated inner tank is set to a predetermined pressure by the pressure increasing means. Boost and hold.

  Next, the present invention will be described in detail based on embodiments.

  FIG. 1 shows an embodiment of a large cryogenic liquefied gas storage tank of the present invention. In the figure, reference numeral 1 denotes a vacuum insulation cold box (cooling tank) having a heat insulating layer (not shown) formed on the inner peripheral surface thereof, and the inside thereof is kept in a vacuum state. 2 to 5 are a plurality of (4 in this embodiment) inner tanks arranged in the inside of the cold box 1, and each has no outer tank (that is, an inner / outer double tank). Not) Among the inner tanks 2 to 5, the inner tank (dedicated inner tank) 2 is a receiving-only inner tank provided to fill the LNG supplied from the lorry 6, and its operating pressure (that is, the inner tank) The tank internal pressure) is set to about 0.3 MPa. Further, the operation pressure of the inner tank 3 is set to about 0.3 MPa, the inner tank 4 is set to about 0.7 MPa, and the inner tank 5 is set to about 2.2 MPa. Each of the inner tanks 2 to 5 has a boosting means (not shown) for boosting and maintaining the internal pressure at the above operating pressure. Each of these boosting means takes out the LNG in each of the inner tanks 2 to 5 from the bottom of each of the inner tanks 2 to 5, vaporizes it with a vaporizer and then returns it to the top of each of the inner tanks 2 to 5. The operating pressure is increased and maintained. Reference numeral 7 denotes a feed pump, which is provided in an LNG take-out pipe (cryogenic liquefied gas take-out pipe) 10 extending from the bottom of the inner tank 2 dedicated to reception. Reference numerals 11 to 13 denote inlet pipes extending from the downstream side portion of the feed pump 7 of the LNG take-out pipe 10 to the bottom of the inner tanks 3 to 5, and reference numerals 14 to 16 denote LNG lead-out pipes extending from the bottom of the inner tanks 3 to 5. The LNG lead-out pipe 14 extending from the bottom of the inner tank 3 is connected to a low-pressure LNG supply pipe 17 with a pressure reducing valve 17a, and the LNG lead-out pipe 15 extending from the bottom of the inner tank 4 is connected to an intermediate pressure LNG supply pipe 18 with a pressure reducing valve 18a. The LNG outlet pipe 16 extending from the bottom of the inner tank 5 is connected to a high pressure LNG supply pipe 19 with a pressure reducing valve 19a. In the figure, 1a is a mounting table for the inner tanks 2 to 5, 11a, 12a and 13a are on-off valves provided in the inlet pipes 11 to 13, and 20 is a filling line.

  Such a large cryogenic liquefied gas storage tank can be filled with LNG as follows. That is, first, LNG in the LNG storage tank 6a (operating pressure 0.55 MPa) mounted on the lorry 6 is filled into the inner tank 2 dedicated for reception by differential pressure filling, and then the on-off valves 11a of the inlet pipes 11 to 13 are filled. -13a is opened / closed, the feed pump 7 is driven, and the LNG taken out from the inner tank 2 by the LNG take-out pipe 10 is timely transferred to the inner tanks 3 to 5 held at a predetermined pressure and filled. The pressure is increased and maintained at a predetermined operating pressure by the pressure increasing means. And when supplying the low pressure LNG of about 0.15 MPa to the customer side, the LNG in the inner tank 3 is supplied by the low pressure LNG supply pipe 17 and the medium pressure LNG of about 0.6 MPa is supplied to the customer side. In this case, when the LNG in the inner tank 4 is supplied by the intermediate pressure LNG supply pipe 18 and the high pressure LNG of about 2.1 MPa is supplied to the customer side, the LNG in the inner tank 5 is supplied by the high pressure LNG supply pipe 19. To supply.

  As described above, in this embodiment, since the operating pressure of the receiving-only inner tank 2 is set lower than the operating pressure of the lorry 6, the filling-only inner tank 2 is removed from the receiving-only inner tank 2 before filling. There is no need to perform the pressure work and the pressure work after filling, and the work for filling is simplified. In addition, since the depressurization operation is not performed, BOG does not occur, and it is not necessary to provide facilities for reusing BOG, and the cost is reduced. Moreover, since the LNG is merely transferred between the inner tank 2 and the inner tanks 3 to 5 by the feed pump 7, the flow rate control of the feed pump 7 and the like is simplified. In addition, when a large amount of LNG is filled in the inner tank 2 dedicated to reception, and the LNG in the inner tanks 3 to 5 decreases by a predetermined amount, the feed pump 7 is driven each time to replenish LNG. No more worries about BOG. Moreover, since the operating pressures of the inner tanks 3 to 5 can be set for various supply conditions, it is not necessary to have several types of feed pumps 7 even when there are several types of supply pressures. And since each inner tank 2-5 is accommodated in the cool box 1, what comprised only the inner tank 2-5 can be used as a storage tank for filling LNG (namely, inner and outer double tank) The installation space for the large cryogenic liquefied gas storage tank can be reduced accordingly. Moreover, since the four inner tubs 2 to 5 are covered with one cool box 1, the ratio of the outer surface area to the total storage amount is reduced, and the evaporation amount per unit storage amount is reduced.

  FIG. 2 shows another embodiment of the large cryogenic liquefied gas storage tank of the present invention. In this embodiment, in addition to the four inner tanks 2 to 5, the LNG take-out pipe 10, the inlet pipes 11 to 13, the LNG outlet pipes 14 to 16, and the filling line 19 are disposed inside the cold box 1. Yes. Moreover, the mounting shelf 1b for mounting the inner tubs 2 to 5 is configured by mounting and fixing a heat insulating layer on a shelf body formed in a lattice shape (not shown). The lower space of the shelf 1b is also insulated and vacuumed. Other parts are the same as those in the above embodiment, and the same reference numerals are given to the same parts. This embodiment also has the same operations and effects as the above embodiment.

  In both the above embodiments, pearlite may be filled in the cold box 1.

It is explanatory drawing which shows one Embodiment of the large cryogenic liquefied gas storage tank of this invention. It is explanatory drawing which shows other embodiment of the large cryogenic liquefied gas storage tank of this invention. It is explanatory drawing which shows a prior art example. It is explanatory drawing which shows another prior art example.

Explanation of symbols

1 Cold storage box 2-5 Inner tank 6 Raleigh 7 Feed pump 10 LNG take-out pipe

Claims (2)

  A large cryogenic liquefied gas storage tank comprising a plurality of inner tanks for filling a cryogenic liquefied gas and a cold storage tank for housing the plurality of inner tanks, wherein one inner tank is a lorry It is a dedicated inner tank that fills the inner tank with the cryogenic liquefied gas stored in the tank, using the differential pressure between the tank internal pressure and the inner tank internal pressure. The extraction pipe is extended to an inner tank other than the dedicated inner tank, and the cryogenic liquefied gas taken out from the dedicated inner tank is sent to the inner tank other than the dedicated inner tank. A large cryogenic liquefied gas storage tank provided with a feed pump for filling. The large cryogenic liquefied gas storage tank according to claim 1, wherein an inner tank other than the dedicated inner tank has a pressure increasing means for increasing the internal pressure.