JP6171272B2 - Liquefied gas delivery equipment - Google Patents

Description

  The present invention relates to a liquefied gas discharge facility.

  Conventionally, a tank for storing liquefied gas such as LNG (Liquefied Natural Gas) or LPG (Liquefied Petroleum Gas) has been provided with a dispensing device for dispensing the liquefied gas stored in the tank. Generally, a liquefied gas storage facility is provided with a plurality of tanks, and a dispensing device is provided for each tank.

  By the way, the composition of the liquefied gas stored in the plurality of tanks installed as described above is not necessarily the same. For example, in a facility for storing LNG, the LNG production area stored in some tanks may be different from the LNG production area stored in other tanks. May be slightly different.

  The LNG discharged from such a liquefied gas storage facility is supplied to facilities such as a thermal power plant. At this time, if the composition of the supplied liquefied gas changes and the calorie changes rapidly, the response at the payout destination equipment may not be in time, which may adversely affect the payout destination equipment. Therefore, in order to moderate the calorie fluctuation of the discharged liquefied gas, when switching the tank from which the liquefied gas is discharged, there is a technology for mixing the liquefied gas in the two tanks in the mixing tank and gradually changing the mixing ratio. Used (see Patent Document 1).

Japanese Patent Laid-Open No. 61-159143

  However, if a mixing tank is to be installed, it will be obvious that construction for installing the mixing tank is required. The construction work for installing such a mixing tank will lead to a longer construction period when a new liquefied gas storage facility is constructed, and a large-scale installation when it is separately installed in an existing liquefied gas storage facility. It will be something.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent rapid calorie fluctuation of discharged liquefied gas without installing a mixing tank in a liquefied gas discharging facility.

  The present invention adopts the following configuration as means for solving the above-described problems.

  According to a first aspect of the present invention, there are provided a plurality of dispensing devices each having a plurality of dispensing devices each having a dispensing pump that sends liquefied gas from a tank and an overload prevention flow rate regulating valve that limits the dispensing flow rate at the upper limit flow rate of the dispensing pump. A liquefied gas discharge facility provided, wherein the discharged liquefied gas is switched from the liquefied gas stored in the first tank to the liquefied gas stored in the second tank, and calories per unit time of the liquefied gas discharged. In order to prevent the fluctuation from exceeding a preset threshold value, the opening of the flow control valve for preventing overload of the dispensing device installed in the first tank is reduced, and the dispensing provided in the second tank A configuration is adopted in which control means for increasing the opening degree of the overload prevention flow control valve of the apparatus is provided.

  A second invention is based on the flow rate change rate set so that the calorie fluctuation per unit time of the liquefied gas to be discharged does not exceed a preset threshold value in the first invention. The opening of the overload prevention flow control valve of the dispensing device installed in the first tank and the opening of the overload prevention flow control valve of the dispensing device installed in the second tank; Adopting a configuration that adjusts.

  According to a third invention, in the first or second invention, the dispensing device returns the flow rate of the liquefied gas sent by the dispensing pump to the tank from the dispensing pump. A return flow rate adjustment valve for adjusting the return flow rate of the liquefied gas, and the control means calculates the return flow rate calculated from the flow rate indicated by the measurement result of the flowmeter based on the opening degree of the return flow rate adjustment valve. By subtracting, the flow rate of the liquefied gas in the flow control valve for preventing overload is calculated, and the flow control valve for preventing overload is calculated based on the calculated flow rate of the liquefied gas in the flow control valve for preventing overload. The configuration of adjusting the degree of opening is adopted.

  According to the present invention, when the liquefied gas to be dispensed is switched from the liquefied gas stored in the first tank to the liquefied gas stored in the second tank, the calorie fluctuation per unit time of the liquefied gas to be dispensed is previously For reducing the opening of the flow control valve for preventing overload of the dispensing device installed in the first tank so as not to exceed the set threshold, and for preventing overload of the dispensing device installed in the second tank Increase the opening of the flow control valve. According to the present invention, when the tank is switched, the amount of liquefied gas discharged from the first tank gradually decreases, the amount of liquefied gas discharged from the second tank gradually increases, and the first Until the amount of liquefied gas discharged from the tank reaches zero, the liquefied gas stored in the first tank and the liquefied gas stored in the second tank are mixed and discharged. Further, in the discharged liquefied gas, the ratio of the liquefied gas stored in the first tank gradually decreases, and the ratio of the liquefied gas stored in the second tank gradually increases. For this reason, the rapid calorie fluctuation of the liquefied gas discharged can be prevented.

  Further, according to the present invention, the liquefied gas discharged from different tanks is mixed by controlling the overload prevention flow control valve conventionally installed in the discharge device as a safety mechanism. For this reason, it is not necessary to separately install a large-scale apparatus such as a mixing tank, and it is not necessary to perform a large-scale construction such as installing a mixing tank.

  As described above, according to the present invention, in the liquefied gas discharge facility, it is possible to prevent a rapid calorie fluctuation of the discharged liquefied gas without installing a mixing tank.

It is a system flowchart which shows schematic structure of the LNG paying-out facility in one Embodiment of this invention. It is a functional block diagram which shows schematic structure of the LNG dispensing equipment in one Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the LNG dispensing equipment in one Embodiment of this invention .

  Hereinafter, with reference to the drawings, an LNG dispensing facility which is an embodiment of the liquefied gas dispensing facility according to the present invention will be described. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

  FIG. 1 is a system flow diagram showing a schematic configuration of the LNG payout facility 1 of the present embodiment. FIG. 2 is a functional block diagram of the LNG payout facility 1 of the present embodiment. As shown in these drawings, the LNG payout facility 1 of the present embodiment includes a first payout device 2, a second payout device 3, a shipping line 4, and a control processing device 5 (control means). .

  The first dispensing device 2 includes a dispensing pump 2a, a first pipe 2b, a flow meter 2c, a second pipe 2d, a third pipe 2e, an overload prevention flow control valve 2f, and a miniflow control valve 2g. (Return flow rate control valve). As shown in FIG. 1, the discharge pump 2a, the first pipe 2b, the third pipe 2e, and the miniflow control valve 2g constitute a miniflow line 2h.

  The payout pump 2a is connected to a tank T1, which is one of a plurality of tanks provided in the LNG storage facility, and sends out the LNG 10 stored in the tank T1. The first pipe 2b is connected to the payout pump 2a and is a pipe that guides the LNG 10 delivered from the payout pump 2a. The flow meter 2c is installed in the middle of the first pipe 2b, and measures and outputs the flow rate of the LNG 10 dispensed from the dispensing pump 2a.

  The 2nd piping 2d and the 3rd piping 2e are piping formed when the 1st piping 2b branches in 2 hands. The second piping 2 d is connected to the shipping line 4 and guides the LNG 10 to the shipping line 4. The third pipe 2e is connected to the tank T1, and guides the LNG 10 to the tank T1.

  The overload prevention flow control valve 2f is installed in the middle of the second pipe 2d, and when the shipment flow rate exceeds the upper limit flow rate of the discharge pump 2a, the flow rate of the discharge pump 2a is increased. Limit the flow rate. Further, in the LNG dispensing facility 1 of the present embodiment, the overload prevention flow control valve 2f switches the LNG dispensed from the LNG dispensing facility 1 from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2, which will be described later. Alternatively, when the LNG discharged from the LNG dispensing facility 1 is switched from the LNG 11 stored in the tank T2 to the LNG 10 stored in the tank T1, it is used to gradually adjust the flow rate of the LNG 10. The operation when switching the LNG to be paid out from the LNG payout facility 1 will be described in detail later.

  The mini-flow control valve 2g is installed in the middle of the third pipe 2e, and adjusts the flow rate of the LNG 10 flowing through the third pipe 2e. That is, the mini-flow control valve 2g adjusts the return flow rate of the LNG 10 that returns to the tank T1 from the dispensing pump 2a.

  In such a first payout device 2, when the overload prevention flow control valve 2f is opened, the LNG 10 sent out by the payout pump 2a is supplied to the shipping line 4 via the second pipe 2d. Note that the flow rate of the LNG 10 supplied to the shipping line 4 side varies depending on the demand of an external payout destination (for example, a thermal power plant), and may be lower than the lower limit flow rate of the payout pump 2a at which the payout pump 2a can operate normally. At this time, the mini-flow control valve 2g is opened, and a part of the LNG 10 delivered from the dispensing pump 2a is returned to the tank T1. Thus, the flow rate of the LNG 10 sent from the payout pump 2a can be maintained at a flow rate that exceeds the lower limit flow rate of the payout pump 2a while responding to the demand at the payout destination.

  The second dispensing device 3 includes a dispensing pump 3a, a fourth pipe 3b, a flow meter 3c, a fifth pipe 3d, a sixth pipe 3e, an overload prevention flow control valve 3f, and a miniflow control valve 3g. And. As shown in FIG. 1, the discharge pump 3a, the fourth pipe 3b, the sixth pipe 3e, and the miniflow control valve 3g constitute a miniflow line 3h.

  The payout pump 3a is connected to a tank T2 which is one of a plurality of tanks provided in the LNG storage facility, and sends out the LNG 11 stored in the tank T2. The fourth pipe 3b is connected to the payout pump 3a and is a pipe that guides the LNG 11 sent from the payout pump 3a. The flow meter 3c is installed in the middle of the fourth pipe 3b, and measures and outputs the flow rate of the LNG 11 discharged from the discharge pump 3a.

  The 5th piping 3d and the 6th piping 3e are piping formed when the 4th piping 3b branches in 2 hands. The fifth pipe 3 d is connected to the shipping line 4 and guides the LNG 11 to the shipping line 4. The sixth pipe 3e is connected to the tank T2, and guides the LNG 11 to the tank T2.

  The overload prevention flow control valve 3f is installed in the middle of the fifth pipe 3d, and when the shipping flow rate exceeds the upper limit flow rate of the discharge pump 3a, the flow rate of the discharge pump 3a is increased at the upstream flow rate of the discharge pump 3a. Limit the flow rate. Further, in the LNG dispensing facility 1 of the present embodiment, the overload prevention flow control valve 3f switches the LNG dispensed from the LNG dispensing facility 1 from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2 described later. Alternatively, when the LNG discharged from the LNG dispensing facility 1 is switched from the LNG 11 stored in the tank T2 to the LNG 10 stored in the tank T1, it is used to gradually adjust the flow rate of the LNG 11. The operation when switching the LNG to be paid out from the LNG payout facility 1 will be described in detail later.

  The mini-flow control valve 3g is installed in the middle of the sixth pipe 3e, and adjusts the flow rate of the LNG 11 flowing through the sixth pipe 3e. That is, the mini-flow control valve 3g adjusts the return flow rate of the LNG 11 that returns from the dispensing pump 3a to the tank T2.

  In such a second dispensing device 3, when the overload prevention flow control valve 3f is open, the LNG 11 sent out by the dispensing pump 3a is supplied to the shipping line 4 via the fifth pipe 3d. Note that the flow rate of the LNG 11 supplied to the shipping line 4 side varies depending on the demand of an external payout destination (for example, a thermal power plant), and may be lower than the lower limit flow rate of the payout pump 3a in which the payout pump 3a can operate normally. At this time, the mini-flow control valve 3g is opened, and a part of the LNG 11 sent from the dispensing pump 3a is returned to the tank T2. Thus, the flow rate of the LNG 11 sent from the payout pump 3a can be maintained at a flow rate that exceeds the lower limit flow rate of the payout pump 3a while responding to the demand at the payout destination.

  The shipping line 4 is connected to a payout destination through a facility such as a vaporizer (not shown), and guides the LNG 10 supplied from the first payout device 2 and the LNG 11 supplied from the second payout device 3 to the payout destination. To do.

  The control processing device 5 controls the entire operation of the LNG payout facility 1 of the present embodiment. As shown in FIG. 2, in the present embodiment, the control processing device 5 is electrically connected to the overload prevention flow control valve 2 f, the flow meter 2 c, and the miniflow control valve 2 g of the first payout device 2. Yes. Further, the control processing device 5 is electrically connected to the overload-preventing flow control valve 3f, the flow meter 3c, and the miniflow control valve 3g of the second dispensing device 3.

  As shown in FIG. 2, the control processing apparatus 5 includes a processing unit 5a and a storage unit 5b. For example, the processing unit 5a performs calculations based on programs and various data stored in the storage unit 5b. The storage unit 5b stores programs and various data necessary for the control processing device 5 to perform control and calculation. In the LNG payout facility 1 of the present embodiment, the flow rate change rate set so that the calorie fluctuation per unit time of LNG to be paid out does not exceed a preset threshold is stored in the storage unit 5b. ing.

  Here, the flow rate change rate stored in the storage unit 5b will be described. First, one of the tanks T1 and T2 stores the LNG with the highest calorie among the LNG that can be stored in the tanks T1 and T2, and the other is the LNG that can be stored in the tanks T1 and T2. Assume that the one with the lowest calories is stored. In addition, when the LNG to be paid out is switched from one of the LNG with the highest calories and the LNG with the lowest calories to the other, the ratio of the LNG before switching gradually decreases with time in the transition period of switching. Let us consider paying out LNG in which two LNG are mixed so that the ratio of LNG after switching gradually increases. In this case, the calories of LNG that are paid out in the transition period of switching change according to the mixing ratio of the two LNG. For example, when switching from a high-calorie LNG to a low-calorie LNG, the mixing ratio of high-calorie LNG gradually decreases and the mixing ratio of low-calorie LNG gradually increases. Decrease. On the other hand, when switching from low-calorie LNG to high-calorie LNG, the mixing ratio of high-calorie LNG gradually increases and the mixing ratio of low-calorie LNG gradually decreases. To increase. At this time, based on the calorie fluctuation (threshold value) per unit time that can be handled at the payout destination, when switching between the LNG with the highest calorie and the LNG with the lowest calorie, these LNG in unit time The upper limit value of the change rate of the mixing ratio can be obtained. Based on the upper limit value of the change rate of the mixing ratio per unit time, the shipping line from the first payout device 2 can prevent the calorie fluctuation per unit time of the LNG to be paid out from exceeding a preset threshold value. The flow rate change rate of the LNG 10 supplied to 4 and the flow rate change rate of the LNG 11 supplied from the second dispensing device 3 to the shipping line 4 can be determined. The flow rate change rate stored in the storage unit 5b is determined in this way.

  Even when the LNG to be dispensed is switched from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2, the flow rate of the LNG dispensed from the LNG dispensing facility 1 of the present embodiment to the dispensing destination does not change. For this reason, the flow rate change rate of the LNG 10 supplied from the first payout device 2 to the shipping line 4 and the flow rate change rate of the LNG 11 supplied from the second payout device 3 to the shipping line 4 differ only in the direction of change. The absolute value of the amount of change (slope) per unit time is the same. However, in the case where LNG stored in three or more tanks is mixed and dispensed, the gradient of the flow rate change rate changes according to the mixing ratio.

  As described above, the flow rate change rate determined in this way is stored in one of the tank T1 and the tank T2, and the one having the highest calorie among the LNG that can be stored in the tank T1 and the tank T2, On the other hand, it is determined on the assumption that the lowest calorie of the LNG that can be stored in the tank T1 and the tank T2 is stored. For this reason, even if the LNG actually stored in the tank T1 and the tank T2 is different from these, the calorie fluctuation when these LNG is mixed is smaller than the above assumption. Therefore, even if the LNG actually stored in the tank T1 and the tank T2 is different from these, the calorie fluctuation per unit time of the delivered LNG is more than the calorie fluctuation per unit time that can be handled at the payout destination. Get smaller.

  In addition, the calorie of LNG is information that can be known in advance based on the production area of the LNG. For this reason, in determining the flow rate change rate, it is easy to set the LNG with the highest calorie and the LNG with the lowest calorie. In addition, the calorie fluctuation per unit time that can be handled at the payout destination is usually information managed at the payout destination, and can be easily set by receiving information from the payout destination.

  Returning to the description of the control processing device 5. The control processing device 5 switches the LNG delivered from the LNG delivery facility 1 of this embodiment from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2, or from the LNG 10 stored in the tank T2 to the tank T2. When switching to the LNG 10 stored in the tank (hereinafter referred to as “tank switching”), based on the flow rate change rate, the opening degree of the flow regulating valve 2f for preventing overload of the first dispensing equipment 2 and the second dispensing equipment 3 is adjusted with the opening degree of the flow control valve 3f for preventing overload. For example, when switching from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2, the control processing device 5 sets the flow control valve 2f for preventing overload of the first payout facility 2 based on the flow rate change rate. While gradually decreasing the opening, the opening of the flow control valve 3f for preventing overload of the second dispensing equipment 3 is gradually increased. On the other hand, when switching from the LNG 11 stored in the tank T2 to the LNG 10 stored in the tank T1, the control processing device 5 sets the flow control valve 2f for preventing overload of the first payout facility 2 based on the flow rate change rate. While gradually increasing the opening, the opening of the flow control valve 3f for preventing overload of the second dispensing equipment 3 is gradually decreased. In other words, in the present embodiment, the control processing device 5 is used to prevent overloading of the dispensing device installed in the tank (first tank) from which LNG was dispensed before switching based on the flow rate change rate at the time of tank switching. While gradually decreasing the opening degree of the flow rate control valve, the opening degree of the overload prevention flow rate control valve of the dispensing device installed in the tank (second tank) that delivers LNG after switching is gradually increased.

  Further, the control processing device 5 calculates the return flow rate of the LNG 10 returned to the tank T1 from the opening degree of the mini-flow control valve 2g of the first dispensing device 2 at the time of tank switching. Further, the control processing device 5 subtracts the return flow rate from the flow rate indicated by the measurement result of the flow meter 2c, whereby the flow rate of the LNG 10 in the overload prevention flow rate regulating valve 2f (ie, from the first payout device 2 to the shipping line 4). The flow rate of the LNG 10 supplied to the LNG 10 is calculated. At the time of tank switching, the control processing device 5 compares the flow rate of the LNG 10 in the overload prevention flow rate control valve 2f calculated as described above with the flow rate calculated based on the previously stored flow rate change rate. Based on this deviation amount, the opening degree of the overload prevention flow control valve 2f is finely adjusted.

  Further, the control processing device 5 calculates the return flow rate of the LNG 11 returned to the tank T2 from the opening degree of the mini-flow control valve 3g of the second dispensing device 3 at the time of tank switching. Further, the control processing device 5 subtracts the return flow rate from the flow rate indicated by the measurement result of the flow meter 3c, whereby the flow rate of the LNG 11 in the overload prevention flow rate adjusting valve 3f (that is, from the second dispensing device 3 to the shipping line 4). The flow rate of the LNG 11 supplied to the LNG 11 is calculated. At the time of tank switching, the control processing device 5 compares the flow rate of the LNG 11 in the overload prevention flow rate regulating valve 3f calculated as described above with the flow rate calculated based on the previously stored flow rate change rate. Then, the opening degree of the overload prevention flow control valve 3f is finely adjusted based on the deviation amount.

  After the switching of the tank is completed, the overload prevention flow rate adjustment valve 2f and the overload prevention flow rate adjustment valve 3f have the original function (that is, the discharge flow rate at the upstream flow rate of the discharge pump 2a and the discharge pump 3a). Need to go back to the function that restricts For this reason, finally, when the tank switching is completed, the overload prevention flow control valve of the dispensing device installed on the tank side that dispenses LNG after the switching is set to 100% of the opening degree and the switching is performed. The overload prevention flow control valve of the dispensing device installed on the tank side that stops the LNG dispensing later needs to have an opening of 0%. At this time, when the shipment flow rate (payout amount) depending on the demand of the payout destination is small, the flow rate delivered from the payout pump is small. For this reason, when the opening of the flow control valve for preventing overload of the dispensing device installed on the tank side that dispenses LNG after switching is gradually increased when the tank is switched, the flow regulating valve for preventing overload is opened. Before the degree reaches 100% of the setting, the flow rate to be discharged reaches the shipment flow rate, and from here on, even if the opening degree of the flow control valve for overload prevention is increased, it passes through the flow control valve for overload prevention. The flow rate does not increase. Therefore, the flow rate of LNG in the flow control valve for preventing overload calculated as described above does not match the flow rate calculated based on the flow rate change rate stored in advance. Therefore, the control processing device 5 calculates the overload calculated in the overload prevention control valve of the dispensing device installed on the tank side that dispenses LNG after switching after the time when the dispensed flow rate reaches the shipping flow rate. The flow rate of LNG in the flow control valve for prevention is compared with the flow rate calculated based on the flow rate change rate stored in advance, and the opening degree of the flow control valve for overload prevention is finely adjusted based on this deviation amount. Stop that.

  Similarly, in the case where the shipment flow rate (payout amount) depending on the demand of the payout destination is small, for this reason, at the time of tank switching, a payout device installed on the tank side that pays out LNG before switching When the opening of the flow control valve for overload prevention gradually decreases, the opening of the flow control valve for overload prevention opens more than the opening corresponding to the shipment flow rate at the start of reduction, and the flow adjustment for overload prevention Even if the opening degree of the valve is decreased, the flow rate passing through the overload prevention flow control valve does not decrease. Therefore, the flow rate of LNG in the flow control valve for preventing overload calculated as described above does not match the flow rate calculated based on the flow rate change rate stored in advance. Therefore, the control processing device 5 uses the calculated overload prevention control valve of the dispensing device installed on the tank side that dispenses LNG before switching until the time when the dispensed flow rate reaches the shipping flow rate has elapsed. Compare the flow rate of LNG in the flow control valve for load prevention with the flow rate calculated based on the flow rate change rate stored in advance, and finely adjust the opening degree of the flow control valve for overload prevention based on this deviation amount To stop doing.

  Next, the operation | movement at the time of the switching of the tank of the LNG dispensing equipment 1 of this embodiment comprised in this way is demonstrated with reference to the flowchart of FIG. In the following description, the case and operation in which the LNG to be paid out is switched from the LNG 10 stored in the tank T1 to the LNG 11 stored in the tank T2 will be described.

  First, the control processing device 5 sets a flow rate change rate (step S1). Here, the control processing device 5 sets the flow rate change rate by storing the flow rate change rate for the first payout device 2 and the flow rate change rate for the second payout device 3 in the storage unit 5b. Subsequently, the control processing device 5 sets an end time (step S2). Here, based on the flow rate change rate set in step S1, the control processing device 5 obtains the change rate of the opening between the overload prevention flow rate control valve 2f and the overload prevention flow rate control valve 3f, The time until the opening of the load prevention flow control valve 2f reaches 100% of the setting and the opening of the overload prevention flow control valve 3f becomes 0% is calculated as the end time, and the calculated end time is calculated as the end time. The end time is set by storing in the storage unit 5b. Here, as described above, the flow rate change rate with respect to the first payout device 2 and the flow rate change rate with respect to the second payout device 3 are different only in the direction of change, and the inclination is the same. The change rate of the opening degree of the flow rate adjusting valve 2f is the same as the change rate of the opening degree of the overload preventing flow rate adjusting valve 3f. Therefore, only one of the change rate of the opening degree of the overload prevention flow rate control valve 2f and the change rate of the opening degree of the overload prevention flow rate control valve 3f may be calculated. Similarly, the time until the opening degree of the flow control valve 2f for overload prevention becomes 100% of the setting and the time period until the opening degree of the flow control valve 3f for overload prevention becomes 0% are similarly the same. Therefore, only one of them may be calculated.

  Subsequently, the control processing device 5 adjusts the opening degrees of the overload prevention flow control valve 2f and the overload prevention flow control valve 3f (step S3). Here, the control processing device 5 calculates the opening degrees of the overload prevention flow control valve 2f and the overload prevention flow control valve 3f at the current time based on the flow rate change rate, and based on the calculation result. Then, the opening degree of the overload prevention flow control valve 2f and the overload prevention flow control valve 3f are set. Note that the control processing device 5 calculates the flow rate of LNG in the overload prevention flow rate control valve 3f as described above when the current time has not passed the time when the discharged flow rate reaches the shipment flow rate. Then, the flow rate is compared with the flow rate calculated based on the flow rate change rate, and the opening degree of the overload prevention flow rate control valve 3f is finely adjusted based on the deviation amount. Further, when the current time has passed the time when the dispensed flow rate reaches the shipment flow rate, the control processing device 5 calculates the flow rate of LNG in the overload prevention flow control valve 2f as described above. Then, the flow rate is compared with the flow rate calculated based on the flow rate change rate, and the opening degree of the overload prevention flow rate control valve 2f is finely adjusted based on the deviation amount.

  Subsequently, the control processing device 5 waits for the unit time to elapse (step S4), and when the end time has not been reached (step S5), calculates the payout amount (step S6). Here, the control processing device 5 calculates the flow rates of the overload prevention flow rate control valve 2f and the overload prevention flow rate control valve 3f after the elapse of the unit time based on the flow rate change rate. And the control processing apparatus 5 performs step S3 again based on the flow volume calculated by step S6.

  The control processing device 5 repeats steps S3 to S6 in this way, and when the end time is reached (step S5), the operation at the time of switching the tank is stopped.

  According to the LNG payout facility 1 of the present embodiment as described above, when the LNG to be paid out is switched from the LNG 10 stored in the tank T1 to the LNG11 stored in the tank T2, the calorie fluctuation per unit time of the LNG to be paid out Tank T2 while decreasing the opening degree of the flow control valve 2f for preventing overload of the first payout device 2 installed in the tank T1 so that does not exceed a preset threshold value (variation rate that can be handled by the payout destination). The opening degree of the flow control valve 3f for preventing overload of the second payout device 3 installed in is increased. According to the LNG dispensing equipment 1 of this embodiment, when the tank is switched, the amount of LNG 10 discharged from the tank T1 gradually decreases, the amount of NG11 discharged from the tank T2 gradually increases, and the tank T1 The LNG 10 stored in the tank T1 and the LNG 11 stored in the tank T2 are mixed and discharged until the amount of LNG 10 discharged from the tank becomes zero. Further, in the LNG to be paid out, the ratio of LNG 10 stored in the tank T1 gradually decreases, and the ratio of LNG 11 stored in the tank T2 gradually increases. For this reason, the sudden calorie fluctuation of LNG to be paid out can be prevented.

  Moreover, according to the LNG dispensing equipment 1 of the present embodiment, the LNG dispensed from different tanks is mixed by controlling the flow control valve for preventing overload that has been conventionally installed in the dispensing device as a safety mechanism. ing. For this reason, it is not necessary to separately install a large-scale apparatus such as a mixing tank, and it is not necessary to perform a large-scale construction such as installing a mixing tank.

  Thus, according to the LNG payout equipment 1 of the present embodiment, it is possible to prevent a rapid calorie fluctuation of the LNG to be paid out without installing a mixing tank.

  Further, according to the LNG payout facility 1 of the present embodiment, the LNG calories are adjusted using the flow rate change rates in the first payout device 2 and the second payout device 3. For this reason, the calorie of LNG can be easily adjusted using the value of the flow meter conventionally installed in the dispensing device.

  Further, in the LNG dispensing facility 1 of the present embodiment, the return calculated based on the opening of the miniflow control valve 2g (miniflow control valve 3g) from the flow rate indicated by the measurement result of the flowmeter 2c (flowmeter 3c). By subtracting the flow rate, the flow rate of the LNG 10 (LNG11) in the overload prevention flow control valve 2f (overload prevention flow rate control valve 3f) is calculated, and the calculated overload prevention flow control valve 2f (overload prevention) Based on the flow rate of the LNG 10 (LNG11) in the flow rate adjusting valve 3f), the opening degree of the overload preventing flow rate adjusting valve 2f (overload preventing flow rate adjusting valve 3f) is adjusted. The flow rate of the LNG 10 (LNG11) in the overload prevention flow control valve 2f (overload prevention flow control valve 3f) is based on the opening degree of the overload prevention flow control valve 2f (overload prevention flow control valve 3f). Can also be calculated. However, the pressure on the upstream side of the overload prevention flow control valve 2f (overload prevention flow control valve 3f) varies depending on the delivery amount of the discharge pump 2a (discharge pump 3a), and the fluctuation range is the discharge pump 2a ( It covers the entire range of fluctuation of the delivery amount of the dispensing pump 3a). Therefore, the flow rate of the LNG 10 (LNG11) in the overload prevention flow control valve 2f (overload prevention flow control valve 3f) is the same as that of the overload prevention flow control valve 2f (overload prevention flow control valve 3f). If the calculation is based on the degree, the error increases. On the other hand, the pressure upstream of the miniflow control valve 2g (miniflow control valve 3g) is such that when the miniflow control valve 2g (miniflow control valve 3g) is opened, the delivery amount of the discharge pump 2a (discharge pump 3a) is the same. Since it is the lower limit flow rate, it does not fluctuate greatly. Therefore, the error of the return flow rate calculated based on the opening degree of the miniflow control valve 2g (miniflow control valve 3g) is small. Therefore, by subtracting the return flow rate calculated based on the opening of the miniflow control valve 2g (miniflow control valve 3g) from the flow rate indicated by the measurement result of the flowmeter 2c (flowmeter 3c), more accurately, It becomes possible to calculate the flow rate of the LNG 10 (LNG11) in the overload prevention flow control valve 2f (overload prevention flow control valve 3f).

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

  For example, in the above embodiment, the example in which the flow rate change rate is stored in the storage unit 5b in advance has been described. However, the present invention is not limited to this, for example, storing the calories of LNG stored in the tank in the storage unit 5b, and not based on the LNG with the highest calories and the LNG with the lowest calories, The processing unit 5a may obtain the flow rate change rate based on the actually stored LNG calories. As a result, when the actually stored LNG is not the LNG with the highest calorie or the LNG with the lowest calorie, the gradient of the flow rate change rate can be increased, and the tank switching can be completed in a short time. it can.

  In addition, for example, a sensor that can measure the calories of LNG 10 stored in the tank T1, LNG 11 stored in the tank T2, and LNG to be paid out is installed, and the calorie change rate is calculated based on the calories by changing the flow rate. It is also possible to adjust the opening degree of the overload prevention flow control valve according to the rate of change.

  Moreover, in the said embodiment, the structure whose liquefied gas of this invention is LNG was demonstrated. However, the present invention is not limited to this, and can be applied to liquefied gas discharge equipment for discharging liquefied gas, which is another combustion gas such as LPG, from the tank.

  Moreover, in the said embodiment, the structure which has two tanks was demonstrated. However, the present invention is not limited to this, and can also be applied to a liquefied gas delivery facility including a delivery device installed for each of a plurality of tanks.

  Moreover, in the said embodiment, the structure which adjusts simultaneously the opening degree of the flow control valve 2f for overload prevention and the opening degree of the flow control valve 3f for overload prevention was demonstrated at the time of tank switching. However, the present invention is not limited to this. For example, when flow rate fluctuation is allowed at the payout destination, the overload prevention flow control valve 2f is closed, and then the overload prevention It is also possible to employ a configuration in which the flow rate control valve 3f is opened.

  DESCRIPTION OF SYMBOLS 1 ... LNG delivery equipment (liquefied gas delivery equipment), 2 ... 1st delivery device, 2a ... delivery pump, 2b ... 1st piping, 2c ... flow meter, 2d ... 2nd piping, 2e ... 3rd piping, 2f …… Flow control valve for preventing overload, 2g …… Mini flow control valve (return flow control valve), 2h …… Mini flow line, 3 …… Second dispensing device, 3a …… Discharging pump, 3b …… 4th piping, 3c …… Flow meter, 3d …… 5th piping, 3e …… 6th piping, 3f …… Overload prevention flow control valve, 3g …… Mini flow control valve (return flow control valve) 3h ... Mini flow line, 4 ... Shipping line, 5 ... Control processing device (control means), 5a ... Processing unit, 5b ... Storage unit, T1 ... Tank, T2 ... Tank

Claims (2)

A liquefied gas discharge facility having a plurality of discharge devices each having a discharge pump for delivering liquefied gas from a tank and a flow control valve for preventing overload that limits the discharge flow rate at the upper limit flow rate of the discharge pump. There,
When switching the liquefied gas to be discharged from the liquefied gas stored in the first tank to the liquefied gas stored in the second tank,
While reducing the opening of the overload prevention flow control valve of the dispensing device installed in the first tank so that the calorie fluctuation per unit time of the liquefied gas to be dispensed does not exceed a preset threshold, Control means for increasing the opening degree of the flow control valve for preventing overload of the dispensing device installed in the second tank;
The dispensing device includes a flow meter that measures the flow rate of the liquefied gas sent by the dispensing pump, and a return flow rate adjustment valve that adjusts the return flow rate of the liquefied gas that returns from the discharge pump to the tank. ,
The control means includes
From the flow rate indicated by the measurement result of the flow meter of the dispensing device installed in the first tank, calculated based on the opening degree of the return flow rate control valve of the dispensing device installed in the first tank By subtracting the return flow rate, the flow rate of the liquefied gas in the overload prevention flow rate control valve of the dispensing device installed in the first tank is calculated, and the calculated overload prevention flow rate control valve Adjusting the opening of the overload prevention flow control valve of the dispensing device installed in the first tank based on the flow rate of the liquefied gas in
From the flow rate indicated by the measurement result of the flow meter of the dispensing device installed in the second tank, it was calculated based on the opening of the return flow rate control valve of the dispensing device installed in the second tank By subtracting the return flow rate, the flow rate of the liquefied gas in the overload prevention flow rate control valve of the dispensing device installed in the second tank is calculated, and the calculated overload prevention flow rate control valve The liquefied gas discharge equipment adjusts the opening degree of the flow control valve for preventing overload of the discharge device installed in the second tank based on the flow rate of the liquefied gas.   The control means is configured so that the calorie fluctuation per unit time of the liquefied gas to be discharged is based on a flow rate change rate set so as not to exceed a preset threshold value. The opening degree of the flow control valve for overload prevention and the opening degree of the flow control valve for overload prevention of the dispensing device installed in the second tank are adjusted. Liquefied gas delivery equipment.

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