JP2012197948A - Liquefied gas supplying method and controller for liquefied gas supplying system - Google Patents

Abstract

To provide a liquefied gas supply method capable of uniformly supplying liquefied gas in a plurality of liquefied gas containers to the end in order to stably supply a large amount of liquefied gas.
Information from a liquefied gas amount measurement detector (2) installed in each of a plurality of liquefied gas containers (1) is processed, and a heating device (3) installed in each of the liquefied gas containers is provided. A liquefied gas supply method in which the plurality of liquefied gas containers are connected in parallel by controlling to supply liquefied gas,
Based on the average weight of the liquefied gas in each container, which is a numerical value obtained by comprehensively processing the information from each detector (2) that is a weight measuring device, the weight of the liquefied gas for each container and the A method for supplying a liquefied gas, characterized in that each of the heating devices (3) is controlled such that a difference from an average weight is not more than a predetermined value.
[Selection] Figure 1

Description

  The present invention relates to a liquefied gas supply method by temperature control of a plurality of liquefied gas containers and a control device for a liquefied gas supply system.

  In a scene where a large amount of liquefied gas having a low vapor pressure and a small amount of evaporation at normal temperature is consumed, a method of increasing the evaporation surface area of the liquefied gas or increasing the temperature of the liquefied gas is taken in order to increase the evaporation capacity. As means for realizing this, there are cases where the length of the liquefied gas filling container is increased or a plurality of containers of standard size are arranged in parallel, and the container containing the liquefied gas is heated. Therefore, a system that can stably supply a large amount of liquefied gas while maintaining the evaporation ability by combining a plurality of easily available standard-sized containers in parallel or by using heating in combination has been studied. .

  FIG. 7 is a diagram of a known example 1 showing a control method of a conventional liquefied gas supply device (Patent Document 1). As shown in FIG. 7, the control method of this liquefied gas supply apparatus monitors the remaining amount of liquefied gas (contents) in a plurality of filled containers with a fuel gauge provided in each, The automatic shut-off valves provided individually are sequentially closed from the containers whose remaining amount is below a predetermined reference value set in advance, and the discharge is stopped. As a result, the liquefied gas in all the containers is used up to the minimum remaining amount even when the liquefied gas in each container is differently reduced. However, in this known example 1, there is no means for heating the liquefied gas in the filling container.

  FIG. 8 is a diagram of a known example 2 showing a conventional liquefied gas supply system and supply method (Patent Document 2). As shown in FIG. 8, this liquefied gas supply system and supply method includes a storage section between a plurality of containers for storing liquefied gas and a pressure regulator provided on the downstream side via the gas supply lines of these containers. Is provided. The liquefied gas evaporated at room temperature from the container is stored in the storage section through the supply pipe. This storage unit has a capacity as a buffer whose storage volume can cope with a sudden change in consumption on the supply side, and is supplied from the pressure regulator to the supply side via a gas supply line. . However, even in this known example 2, there is no means for heating the liquefied gas in the container. Further, the means for detecting the remaining amount of liquefied gas in the container is excluded.

  FIG. 9 is a diagram of a known example 3 showing a conventional liquefied gas supply method (Patent Document 3). As shown in FIG. 9, this liquefied gas supply method includes a liquefied gas filling container 100, a first pipe 105 and a second pipe 106 which are supply pipes thereof, and a flow rate detecting means 104, and the liquefied gas is supplied. The filling container 100, the first pipe 105, and the second pipe 106 are respectively measured by the flow rate detection means 104 by the flow rate detection means 104 using the first heating means 101 to the second heating means 102 and the third heating means 103. It is controlled and supplied according to the value. Alternatively, instead of the flow rate detection means 104, a plurality of branch valves 131 to 140 provided at the subsequent stage of the second pipe 106 control and supply the amount of generated heat according to the number of open valves. In this supply method, the heating means is controlled under the condition that gas is always supplied through at least one branch valve. However, in this known example 3, the liquefied gas filling container 100 is a single body, and simultaneous supply from a plurality of containers is not performed. Further, the means for detecting the remaining amount of the liquefied gas contained in the liquefied gas filling container 100 is excluded.

  FIG. 10 is a diagram of a general conventional example 4 showing a conventional liquefied gas supply system including a plurality of containers. As shown in FIG. 10, this system connects a plurality of containers of standard size in parallel, individually heats each container containing liquefied gas, and the remaining amount of liquefied gas in each container is a weigh scale. It is composed of a combination of conventional techniques of measuring with a measuring instrument such as the above. The heating control system of the heating sources 3-1 to 3-n, the heating amount measuring sensors 4-1 to 4-n, the temperature controllers 5-1 to 5-n, and the heating output devices 6-1 to 6-n The measuring system for the amount of liquefied gas in the containers of the measuring devices 2-1 to 2-n is independent for each container.

JP-A-11-226386 JP 2003-28395 A JP 2006-161937

  In the conventional control method of the liquefied gas supply device shown in FIG. 7, it is assumed that the liquefied gas (contents) 2 in the specific container is originally reduced, and each remaining amount is set to a predetermined reference value set in advance. Since the discharge is sequentially stopped from the lower container, the evaporation surface area, which is a condition for maintaining the evaporation capacity, decreases by the amount of the stopped container, and there is a problem that the supply capacity is insufficient when the number is small. Furthermore, since there is no heating means, there is a problem that only the amount of evaporation at room temperature can be taken, and if the number of containers that can be supplied decreases, insufficient supply capacity is accelerated.

  In the conventional liquefied gas supply system and supply method shown in FIG. 8, when a large storage volume of the storage unit 4 is required, or when the temperature of the storage unit 4 is lower than the temperature of the large container 1, There exists a problem that the gas of the storage part 4 vaporized and stored by the container 1 will liquefy again. In other words, the reliquefied state in the storage unit 4 is the same as the transfer from the container 1 to the storage unit 4, and from a single large container having a capacity as a buffer that can cope with a sudden change in consumption. Will be the supply of. Therefore, in order to prevent reliquefaction in the storage unit 4, there is a condition that a temperature environment in which the temperature of the storage unit 4 is always maintained higher than the container 1 side must be created. A problem occurs. In addition, when there are a plurality of containers 1, if the environmental temperature of each container 1 is slightly different, the liquefied gas vapor pressure inside the container is also different, and the liquefied gas in the container with high pressure is stored in the storage unit 4 first. When the containers are replaced at the same time, there is a problem that the remaining amount of the liquefied gas varies greatly unless there is a means as in the known example 1 (FIG. 7).

  In the conventional liquefied gas supply method shown in FIG. 9, each heating means is controlled so that the heat of evaporation of the liquefied gas corresponding to the supply flow rate is generated by the heating means 101, 102, 103. There is an upper limit of the heating temperature to raise the supply capacity, and there is a limit naturally. Further, when a plurality of liquefied gas filling containers 100 are heated by the heating means 101 in order to increase the evaporation surface area by this method, the actual liquefied gas temperature is monitored even if the control amount of the heating means of each container is the same. Therefore, there is a problem that the temperature difference occurs for each container and a uniform evaporation amount cannot be obtained, and only containers having a high heating temperature and a high vapor pressure are reduced.

  In the conventional liquefied gas supply system including a plurality of containers shown in FIG. 10, the temperature controller for heating each container detects the surface temperature of the container and controls the temperature. However, in spite of performing such control, there are actually problems such as partial reduction and movement (transfer filling) of liquefied gas between containers.

  According to the knowledge of the inventors, the liquefied gas moves (transfers) between the containers even by a slight temperature difference between the containers, for example, the influence of the wind flow in the container chamber. Therefore, it is only necessary to measure and control the temperature of the liquefied gas itself, but in reality, it is difficult to measure the temperature of the liquefied gas itself in the container.

  As described above, in the prior art, when supplying a plurality of containers containing liquefied gas connected in parallel, the subtle temperature difference that differs from container to container in any case, with or without heating means, There was a common problem that only a container with a high evaporation pressure was reduced, and when the supply was stopped, a container with a high evaporation pressure was transferred from a container with a high evaporation pressure to a low container through the connection part of the container. .

  An object of the present invention is to provide a liquefied gas supply system and a supply method that can uniformly supply liquefied gas in a plurality of liquefied gas containers to the end in order to stably supply a large amount of liquefied gas.

  The above problem is not to adjust individual liquefied gas containers based on predetermined numerical values, but to adjust individual containers based on numerical values obtained from detection information from all containers each time. It can be solved by doing.

  That is, in the first aspect, the present invention processes a plurality of liquefied gas containers, a detector for measuring the amount of liquefied gas installed in each container, a heating device installed in each container, and information from each detector. And a liquefied gas supply system including a control device that controls each heating device, and the control device controls each heating device based on numerical values obtained by comprehensively processing information from each detector. It is characterized by that.

  The measurement item of the amount of liquefied gas may be weight measurement or volume measurement. Moreover, you may measure indirectly as liquid level height. Any known method can be applied as the measurement method.

  In a second aspect, the liquefied gas supply system according to the present invention is characterized in that each detector is a weight measuring device.

  In a third aspect, the liquefied gas supply system according to the present invention is such that the numerical value is an average weight of the liquefied gas in each container, and a difference between the liquefied gas weight and the average weight for each container is equal to or less than a predetermined value. Each of the heating devices is controlled.

  In a fourth aspect, the liquefied gas supply system according to the present invention is characterized in that each detector is a liquefied gas liquid level detector.

  In a fifth aspect, in the liquefied gas supply system according to the present invention, the numerical value is the average liquid level of the liquefied gas in each container, and the liquid level of the liquefied gas for each container is equal to the average liquid level. Each heating device is controlled so that the difference becomes a predetermined value or less.

  In a sixth aspect, the liquefied gas supply system according to the present invention is characterized by having a connection cutoff valve that cuts off the connection between the containers in conjunction with the liquefied gas supply side cutoff valve.

  In a seventh aspect, the present invention processes information from a detector for measuring the amount of liquefied gas installed in each of a plurality of liquefied gas containers, and controls a heating device installed in each of the liquefied gas containers. A liquefied gas supply method for supplying gas, characterized in that each heating device is controlled on the basis of numerical values obtained by comprehensively processing information from each detector.

  In an eighth aspect, the liquefied gas supply method according to the present invention is characterized in that each detector is one of a weight measuring device and a liquid level detector.

  In a ninth aspect, the present invention relates to a liquefaction that processes information from a detector for measuring the amount of liquefied gas installed in each of a plurality of liquefied gas containers and controls a heating device installed in each of the liquefied gas containers. A control device for a gas supply system, wherein each heating device is controlled based on a numerical value obtained by comprehensively processing information from each detector.

  In a tenth aspect, the control device of the liquefied gas supply system according to the present invention is characterized in that each detector is one of a weight measuring device and a liquid level detector.

  According to the present invention, the liquefied gas contained in the plurality of containers is uniformly reduced to the end. Therefore, since all the containers connected in parallel maintain the connection and decrease at the same time while ensuring the evaporation surface area evenly, it is possible to maintain the evaporation capacity at the required liquid temperature from the start to the end of the supply. it can.

  Embodiments of a liquefied gas supply system and a temperature control method according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram showing the configuration of Embodiment 1 of a liquefied gas supply system according to the present invention. As shown in FIG. 1, the liquefied gas supply system of the present invention has a plurality (n) of containers 1-1 to 1-n (1-1 for the first container and 1-n for the nth container). The same applies hereinafter.), Measuring devices 2-1 to 2-n, heating sources 3-1 to 3-n, heating amount measuring sensors 4-1 to 4-n, temperature Adjusters 5-1 to 5-n, heating output devices 6-1 to 6-n, measurement value calculation comparators 7, connection pipes 8, shutoff valves 9, and liquefied gas 10-1 to liquefied gas 10 in each container -N.

  The containers 1-1 to 1-n are of a standard size that can be easily obtained and have the same capacity, and the liquefied gas 10-1 to 10-n in each container is attached before being attached to the supply system. The amount (weight in Example 1) is known. The containers 1-1 to 1-n are connected in parallel by a connecting pipe 8 and led to a shutoff valve 9 in a gas supply / supply line.

  In this state, the amount of liquefied gas in each container (weight in this example) is constantly measured by the measuring devices 2-1 to 2 -n, and the measured value is sent to the measured value calculation comparator 7. In addition, heating sources 3-1 to 3-n and heating amount measuring sensors 4-1 to 4-n are attached to each container. The required liquid temperature derived from the correlation between the vapor pressure and temperature of the liquefied gas obtained in advance is set in the temperature controllers 5-1 to 5 -n, and the measured value calculation comparator 7 is used as the heating output device 6-6. The temperature of the liquefied gas 10-1 to 10-n in the container is PID controlled by the heating sources 3-1 to 3-n via 1 to 6-n. The measurement value calculation comparator 7 calculates the acquired measurement value, and interrupts an output signal obtained by comparison and determination under a predetermined condition into a control signal output from the temperature controllers 5-1 to 5-n. Then, control is performed to correct the output of the heating output devices 6-1 to 6-n.

  2 to 4 are diagrams for explaining the operation of the first embodiment according to the present invention. The operation will be described with reference to FIGS.

  FIG. 2 shows the measured values of the plurality of (n) weighing devices 2-1 to 2-n to be taken into the weighing value calculation comparator 7, W-1 to W-n, and all the values calculated by the weighing value calculation comparator 7. The measurement value is set to Wa, the determination value set in advance of the measurement value calculation comparator 7 as D, and the stop signal output from the measurement value calculation comparator 7 as a result of this determination as OFF-1 to OFF-n. FIG. 6 is a diagram showing signals processed by an arithmetic comparator 7.

  Further, control signal outputs outputted from the temperature controllers 5-1 to 5-n are sent from S-1 to Sn, and from the heating output devices 6-1 to 6-n to the heating sources 3-1 to 3-n. The heating output finally outputted is shown as P-1 to P-n.

  FIG. 3 is a flowchart of the heating control in the present invention. For each of the control signal outputs S-1 to Sn output from the temperature controllers 5-1 to 5-n to the heating output devices 6-1 to 6-n, the measured value calculation comparator 7 measures each measured value. The difference between W-1 to W-n and the average value Wa is calculated, and the stop signal OFF-1 to OFF-n is interrupted according to the determination result by comparing with the determination value D, and the heating sources 3-1 to 3-3. A flow of a series of processes for controlling the outputs P-1 to Pn of -n is shown.

  FIG. 4 shows the control signal outputs S-1 to Sn output from the temperature controllers 5-1 to 5-n to the heating output devices 6-1 to 6-n and the measurement value calculation comparator 7. Then, the stop signal OFF-1 to OFF-n for interrupting the stop signal as a result of the determination to the outputs of the heating output devices 6-1 to 6-n, and the heating source 3 from each heating output device 6-1 to 6-n. It is the figure which showed the amount of the liquefied gas in a container corresponding to the timing chart which shows an example of the ON / OFF signal state of the heating outputs P-1 to Pn finally output to -1 to 3-n .

  In the conventional method, the temperature of each container is only controlled by the temperature controllers 5-1 to 5-n so that the temperature measured by the heating amount measuring sensors 4-1 to 4-n becomes the set temperature. In other words, the temperature control is independent for each container, and the actual temperature of the liquefied gas in the container is slightly different, so the liquefied gas moves (transfers) from a container with a high liquefied gas temperature to a container with a low temperature. In the case of air supply, a phenomenon (decrease) occurs in which only the liquefied gas in the high temperature container is reduced.

  On the other hand, in Example 1 of this invention, the weight of the liquefied gas in each container is always measured with the measuring devices 2-1 to 2-n, and the amount of liquefied gas in each container is comprehensively processed. The heating of the container, which is smaller than a predetermined determination value (D) with respect to a certain amount (average value), is forcibly stopped to suppress the evaporation amount. This is measured and compared at a predetermined interval, and heating of a small number of containers is stopped at the measurement comparison interval each time.

  In FIG. 4, since the container 1-1 has the most reduction method, forced heating stop (OFF-1) works a lot, and the container 1-2 has less reduction method, and the forced heating stop (OFF-2). Indicates a non-working situation. Further, since the container 1-n is slightly reduced from the average value, the frequency of forced heating stop (OFF-n) is less than that of the container 1-1.

  As described above, by calculating and comparing the amount of liquefied gas in each container at regular intervals and forcibly stopping the heating output of the container with a large amount of evaporation less than the average, without reducing only one container, The liquefied gas 10-1 to 10-n contained in the plurality of containers 1-1 to 1-n is reduced evenly to the end. Therefore, since all the containers connected in parallel maintain the connection and decrease simultaneously while ensuring the evaporation surface area evenly to the end, the evaporation ability at the required liquid temperature can be maintained from the start to the end of the supply.

  In the first embodiment, the capacities of the containers are the same, but they are not necessarily the same. However, in that case, the average value of the amount of liquefied gas in each container cannot be used as a reference. In this case, for example, the ratio between the total capacity of the container and the amount of the remaining liquefied gas is calculated for each container, and it can be carried out in the same manner as in the first embodiment by correcting the average to obtain the reference value.

  In addition, the method of measuring the volume instead of the weight as the amount of the liquefied gas may be used. In that case, the embodiment can be similarly implemented by replacing the weight with the volume in the first embodiment.

  FIG. 5 is a diagram showing a configuration of a liquefied gas supply system according to a second embodiment of the present invention. In place of the measuring devices 2-1 to 2-n in FIG. 1 described above, the liquid level sensors 11-1 to 11-1 that detect the liquid level (remaining amount) of the liquefied gas as the liquefied gas remaining amount measuring means in the container. 11-n. Further, in FIG. 2 described above, the measured values of the (n) measuring devices 2-1 to 2-n taken into the measuring value calculation comparator 7 are set as the measured values of the liquid level sensors 11-1 to 11-n. −1 to L−n, the average value of all measurement values calculated by the measurement value calculation comparator 7 is La, the determination value of the measurement value calculation comparator 7 is D, and this determination determines the measurement value calculation comparator 7 The stop signals output from are set to OFF-1 to OFF-n. In FIG. 5, a float type liquid level sensor is shown as a representative example as an example of detecting the liquid level, but a non-contact ultrasonic type or radiation type liquid level sensor may be used.

  A second embodiment will be described with reference to FIG. The liquid level is continuously monitored as the measured value as the amount of liquefied gas in each container, and is taken into the measured value calculation comparator 7. The measured value calculation comparator 7 calculates a difference (La− (L−1) to La− (Ln)) individually for the average value (La). D as the determination value of the weighing value calculation comparator 7, and when the difference by this determination is larger than D, OFF-1 to OFF-n are output as stop signals from the weighing value calculation comparator 7 to the heating output device of the corresponding container. Is done. The following operations are the same as those in FIGS. 3 and 4 described above, and Wa is read as La, W-1 is read as L-1, and Wn is read as Ln.

  In Example 2, the remaining amount of the liquefied gas in the container is directly measured by the liquid level sensor. Unlike the case of measuring the weight or the like as in the first embodiment by directly measuring the liquid level of the liquefied gas, there are few disturbance factors such as connection pipes that affect the weight measurement of the container. In addition, since the liquid level is detected, even when the remaining weight varies due to variations in the container body diameter and the bottom shape, it is possible to control the liquid level evenly until the liquid level reaches the bottom of the container.

  FIG. 6 is a diagram illustrating a configuration of a liquefied gas supply system according to a third embodiment of the present invention. This is obtained by adding the connection cutoff valves 12-1 to 12-n to FIG. 1 described above.

  A third embodiment will be described below with reference to FIG. The operation in the normal supply state is as described in FIG. 1 and FIG. 2 described above, but in a state where each container is connected, the liquefied gas is not necessarily reduced in the supply state. There is a case where the consumption side is stopped and the flow of the gas supply gas is interrupted for a long time, or the shutoff valve 9 is closed and is on standby.

  In this state, the liquefied gas in each container keeps equality by repeatedly transferring and filling between the containers from the higher pressure side to the lower side due to the subtle difference in vapor pressure determined by the respective temperatures. In particular, when the shutoff valve 9 is closed and the air supply is clearly stopped, it is not necessary to keep equality by repeated transfer and filling. In order to avoid this, the connection shutoff valves 12-1 to 12- n is closed in conjunction with the shutoff valve 9 to temporarily shut off the connection of the containers. In addition, the operation | movement at the time of a connection interruption | blocking does not perform forced heating stop (OFF-1 to OFF-n), but only temperature-controls with the temperature regulators 5-1 to 5-n.

  In Example 3, especially when the liquefied gas in each container is waiting in a full state, the operation comparison for maintaining the equality of the present invention and the forced heating stop function do not operate or the heating sources 3-1 to 3-1 There is a risk that the liquefied gas in each container overflows due to transfer and filling caused by a subtle difference in vapor pressure determined by the respective temperatures, such as when 3-n unexpectedly fails. However, safety can be ensured by blocking the connection of the containers by the connection blocking valves 12-1 to 12-n.

  Although the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the configurations of the above-described embodiments, and various modifications that can be made by those skilled in the art within the scope of the present invention. Of course, including modifications.

It is a figure which shows the structure of Example 1 of the liquefied gas supply system which concerns on this invention. It is a figure which shows the signal processed by the measurement value calculation comparator in this invention. It is a flowchart of the heating control in this invention. It is a timing chart which shows an example of the control signal in this invention, and a figure which shows the amount of liquefied gas. It is a figure which shows the structure of Example 2 of the liquefied gas supply system which concerns on this invention. It is a figure which shows the structure of Example 3 of the liquefied gas supply system which concerns on this invention. It is a figure of well-known example 1 which shows the control method of the conventional liquefied gas supply apparatus. It is a figure of the well-known example 2 which shows the conventional liquefied gas supply system and supply method. It is a figure of the well-known example 3 which shows the conventional liquefied gas supply method. It is a figure of the general well-known example 4 which shows the conventional liquefied gas supply system which consists of several containers.

DESCRIPTION OF SYMBOLS 1 (Liquefied gas) container 2 Measuring device 3 Heating source 4 Heating amount measurement sensor 5 Temperature controller 6 Heating output device 7 Weighing value calculation comparator 8 Connecting pipe 9 Shut-off valve 10 Liquid gas 11 Liquid level sensor 12 Connecting shut-off valve W Weight Measurement value Wa Average value of weight measurement value OFF Stop signal S Control signal output P Heating output L Measurement value of liquid level La Average value D of measurement value of liquid level D Determination value

Claims (2)

The plurality of liquefied gas containers are arranged in parallel by processing information from the detectors for measuring the amount of liquefied gas installed in each of the plurality of liquefied gas containers and controlling a heating device installed in each of the liquefied gas containers. A liquefied gas supply method for connecting and supplying a liquefied gas,
Based on the average weight of the liquefied gas in each container, which is a numerical value obtained by comprehensively processing the information from each detector that is a weight measuring device, the liquefied gas weight for each container and the average weight A method for supplying a liquefied gas, characterized in that each of the heating devices is controlled so that the difference between the two becomes a predetermined value or less. Processing information from a detector for measuring the amount of liquefied gas installed in each of a plurality of liquefied gas containers connected in parallel to supply liquefied gas, and controlling a heating device installed in each of the liquefied gas containers; A control device for a liquefied gas supply system,
Based on the average weight of the liquefied gas in each container, which is a numerical value obtained by comprehensively processing the information from each detector that is a weight measuring device, the liquefied gas weight for each container and the average weight A control device for a liquefied gas supply system, wherein each of the heating devices is controlled so that a difference between the two values becomes a predetermined value or less.

Images