JP5090823B2 - Liquid gas delivery method - Google Patents

Description

  The present invention relates to a method for feeding a liquefied gas, and more particularly to a method for feeding a liquefied gas in which a predetermined amount of liquefied gas is sent to a user at a predetermined time interval at a predetermined time interval.

For example, as a method of sending liquefied gas stored in a liquefied gas storage tank, a method of using a liquefied gas pump or pressurizing the storage tank with a self-pressurizing evaporator is widely used (for example, (See Patent Documents 1 and 2.)
Utility Model Registration No. 3065131 JP-A-7-289880

  The conventional liquid feeding method has no problem in supplying a large amount of liquefied gas continuously, but it is used for supplying a certain amount of liquefied gas intermittently, in particular, the stop time is longer than the liquid feeding time. Sometimes it was not suitable. For example, when using a liquefied gas pump, it is necessary to use a liquefied gas pump with a capacity suitable for the amount of liquid delivered at the time of liquid delivery. I had to. In addition, when using a self-pressurizing evaporator, not only a large amount of heat is required to send liquefied gas stably, but pressure overshoot is likely to occur, and precise control is difficult. In addition, when the pressure in the storage tank increases, the temperature of the liquefied gas to be fed rises, so that there is a problem that gasification is likely to occur during the feeding.

  In the method of controlling the amount of liquefied gas sent with a flow meter, when a certain amount of liquefied gas is sent, the product of the flow rate of the liquefied gas and the time for feeding must be calculated and controlled. Since the amount of liquefied gas delivered is not directly measured, it is difficult to control the amount of delivered fluid with high accuracy.

  Accordingly, an object of the present invention is to provide a method for feeding a liquefied gas that can reduce the apparatus cost when the liquefied gas is intermittently fed and can control the amount of the liquid fed with high accuracy. .

In order to achieve the above-mentioned object, the liquid gas delivery method of the present invention is a liquid gas delivery method for intermittently delivering a liquid gas to a use destination, in which the liquid delivery to the use destination is stopped. The liquefied gas from the liquefied gas source is boosted by the liquefied gas pump and supplied to the liquid feeding container, and part of the boosted liquefied gas is vaporized, and the vaporized gas is held at a preset pressure and used. Introducing the vaporized gas into the liquid-feeding container when the liquid is sent to the destination, and sending the liquefied gas stored in the liquid-feeding container to the use destination, and from the liquefied gas source The supply of the liquefied gas to the liquid feeding container is stopped, and in this case, the liquefied gas to be vaporized is branched from between the liquefied gas pump and the liquid feeding container, and the branch position Liquefied gas pump side downstream It is characterized in that a back pressure valve which opens when the above pressure the pressure is set in advance. In particular, the time for increasing the pressure of the liquefied gas from the liquefied gas source by the liquefied gas pump and supplying the liquefied gas to the liquid sending container is longer than the time for stopping the supply of the liquefied gas from the liquefied gas source to the liquid sending container. It is a feature.

Furthermore, the liquid gas feeding method of the present invention is characterized in that the weight of the liquid feeding container is measured to control the amount of liquid gas fed to the user.

  According to the method for feeding a liquefied gas of the present invention, the liquefied pump supplies and stores the liquefied gas in the liquid sending container when the liquid feeding is stopped, and the liquid gas stored in the liquid feeding container is fed when the liquid is sent. Therefore, in particular, when sending a large amount of liquefied gas in a short period of time compared to the stop time, a predetermined amount of liquefied gas should be stored in the feed container during the stop time. Therefore, a liquefied gas pump having a smaller capacity than the amount of liquid fed per hour at the time of liquid feeding can be used.

  FIG. 1 is a system diagram showing an example of a liquefied gas delivery device for carrying out the liquefied gas delivery method of the present invention. This liquefied gas delivery apparatus temporarily stores a liquefied gas container 11 serving as a liquefied gas source, a liquefied gas pump 12 that extracts and sends out the liquefied gas in the liquefied gas container 11, and a liquefied gas supplied from the liquefied gas pump 12. The liquid-feeding container 13 stored in the liquid-feeding container 13, the liquefied gas evaporator 14 for obtaining the pressurized gas introduced into the liquid-feeding container 13 when the liquefied gas is fed from the liquid-feeding container 13, and the connection And a variety of valves provided at predetermined positions in each path are main components. The liquid supply container 13 includes a weigh scale (load cell) 15 for measuring weight, and a container internal temperature. And a temperature controller 16 for measuring and keeping the temperature constant.

  The liquefied gas pump 12 includes a circulation path 17 that circulates the liquefied gas discharged from the liquefied gas pump 12 to the suction side of the liquefied gas pump 12, a liquefied gas pump 12 that cools the liquefied gas sucked by the liquefied gas pump 12, and a liquefied gas pump. In order to maintain the performance, a refrigerator 18 for re-cooling the evaporative gas is provided. In the portion of the liquefied gas evaporator 14, a heater 19 for heating and evaporating the liquefied gas, and the vaporized gas are provided. A buffer tank 20 is provided for storage.

  Hereinafter, a procedure for intermittently feeding the liquefied gas will be described. First, the container valves 11a and 11b of the liquefied gas container 11 are connected to the liquefied gas supply path 21 and the pressurizing path 22, and the container valves 11a and 11b and the manual valves 23, 24, 25, and 26 are opened. The back pressure valves 27 and 28 and the pressure reducing valves 29 and 30 are adjusted to preset operating pressures. Further, after adjusting the set pressure of the pressure indicating controller 32 for controlling the opening and closing of the pressurizing adjustment valve 31 to a preset operating pressure, the motor 12a of the liquefied gas pump 12 is operated to perform a precooling operation in the system.

  After the pre-cooling operation is completed, the liquefied gas supply valve 35 is opened with the liquid feeding valve 33 and the circulation valve 34 closed, and supply of the liquefied gas to the liquid feeding container 13 is started. At the start of supply, the decompression adjustment valve 39 is opened by the set pressure of the pressure indicating controller 32, and the vaporized gas is released from the liquid supply container 13 to reduce the pressure in the container, so that the liquefied gas is easily supplied. And When the pressure of the liquefied gas extracted from the liquefied gas container 11 to the liquefied gas supply path 21 and increased in pressure by the liquefied gas pump 12 becomes equal to or higher than the set pressure of the supply-side back pressure valve 27, the supply-side back pressure valve 27 is opened. The liquefied gas is supplied to the liquid feeding container 13 through the pressure valve 27 and the liquefied gas supply valve 35.

  The supply amount of the liquefied gas to the liquid supply container 13 is controlled by measuring the weight of the liquid supply container 13 with the load cell 15, and when the measured weight reaches a preset weight, the liquefied gas supply valve 35. Is closed, and the supply of the liquefied gas to the liquid feeding container 13 is stopped. As a result, a standby state in which a predetermined amount of liquefied gas is stored in the liquid-feeding container 13 is entered, and the temperature controller 16 is activated to keep the temperature in the liquid-feeding container 13 constant. The pressure in the liquid feeding container 13 at this time is equivalent to the discharge pressure of the liquefied gas pump 12. Thereafter, the pressurization control valve 31 is opened, and the pressure in the liquid feeding container 13 is increased to the set pressure of the liquid feeding side pressure reducing valve 29.

  In the standby state, the liquefied gas supply valve 35 is closed, and at the same time, the circulation valve 34 of the circulation path 17 is opened. The set pressure of the circulation-side back pressure valve 28 provided in the circulation path 17 is set slightly higher than the set pressure of the supply-side back pressure valve 27. Usually, while the liquefied gas is being supplied to the liquid sending container 13 Is closed, but the liquefied gas supplied from the liquefied gas pump 12 is opened when the liquefied gas supply valve 35 is closed and the primary pressure of the circulation-side back pressure valve 28 exceeds the set pressure. It flows through the circulation path 17 via the circulation-side back pressure valve 28 and the circulation valve 34 in the valve state, and circulates to the suction side of the liquefied gas pump 12 via the refrigerator 18. Thereby, the discharge pressure of the liquefied gas pump 12 is held at the set pressure of the circulation side back pressure valve 28, and the liquefied gas pump 12 is held at a low temperature.

  On the other hand, part of the liquefied gas discharged from the liquefied gas pump 12 branches from the liquefied gas supply path 21 between the liquefied gas pump 12 and the supply-side back pressure valve 27 to the pressurization source supply path 36, and the manual valves 24 and 25. Then, the gas is introduced into the liquefied gas evaporator 14 and the heater 19 is activated to vaporize the liquefied gas. The vaporized gas branches through the manual valve 26 into the pressurizing path 22 and the liquid feeding pressurizing path 37, and the gas branched into the liquid feeding pressurizing path 37 is stored in the buffer tank 20. At this time, the primary sides of the pressure reducing valves 29 and 30 and the buffer tank 20 are held at the set pressure of the supply-side back pressure valve 27 on the discharge side of the liquefied gas pump 12 via the liquefied gas evaporator 14.

  Further, since the pressurization side pressure reducing valve 30 of the pressurization path 22 opens and closes according to the pressure on the secondary side, the inside of the liquefied gas container 11 becomes the set pressure of the pressurization side pressure reducing valve 30 via the pressurization path 22. Retained. In the liquid supply pressurizing path 37, the pressure adjustment valve 31 is closed when the pressure in the liquid supply container 13 is higher than the set pressure of the pressure indicating controller 32. The pressure between the side pressure reducing valve 29 is maintained at the set pressure of the liquid feeding side pressure reducing valve 29.

  By opening the liquid supply valve 33 in the standby state, the liquefied gas stored in the liquid supply container 13 is supplied to the user through the liquid supply path 38. The liquefied gas is fed by the pressure in the liquid feeding container 13, and during the feeding of the liquefied gas, the pressurization adjusting valve 31 is opened, and the liquid feeding gas is fed into the liquid feeding container 13 from the liquid feeding pressurizing path 37. The pressurized gas is introduced to keep the liquid feeding pressure constant.

  The amount of liquefied gas delivered was controlled by measuring the weight of the delivery vessel 13 with the load cell 15, and the difference between the measured weight before the start of delivery and the measured weight during delivery was preset. When the liquefied gas feed amount is reached, the liquid feed valve 33 is closed and the liquefied gas feed is stopped. As described above, since the weight of the liquefied gas is directly measured by the load cell 15 as compared with the case where the flow meter is used, the amount of liquid fed can be controlled with higher accuracy. Further, the temperature in the liquid supply container 13 is kept constant by the temperature controller 16, and the temperature of the liquefied gas supplied to the use destination can be controlled.

  When the liquid supply valve 33 is closed and the liquid supply of the liquefied gas to the user is stopped, the circulation valve 34 of the circulation path 17 is closed and the liquefied gas supply valve 35 is opened, and the liquefied gas boosted by the liquefied gas pump 12 is supplied. As described above, after supplying the liquefied gas into the liquid-feeding container 13 until the measured weight of the liquid-feeding container 13 reaches the set weight as described above, the same waiting is performed as described above. State.

  Further, when the pressure on the pressurization source supply path 36 decreases during the liquid gas supply to the use destination and during the liquid supply stop, when the pressure becomes lower than the set pressure of the supply side back pressure valve 27, the supply side back pressure valve 27 is Since the liquefied gas that has been closed and pressurized by the liquefied gas pump 12 is introduced into the pressurization source supply path 36, the pressure of the gas for pressurizing the liquefied gas container 11 and the liquid supply container 13 is controlled by the supply-side back pressure valve 27. It can be securely held at a pressure higher than the set pressure.

  In this way, after supplying a predetermined amount of liquefied gas to the liquid-feeding container 13 in the initial preparation stage and storing it, the liquid-feeding liquid is supplied when the liquefied gas is fed from the liquid-feeding container 13 to the use destination. By stopping the supply of the liquefied gas to the container 13, the supply amount of the liquefied gas can be accurately controlled from the weight of the liquid supply container 13. Furthermore, by adjusting the pressure of the gas in the liquid feeding container 13, a large amount of liquefied gas can be fed in a short time.

  When the liquid gas is sent intermittently to the user and the liquid feed stop time is longer than the liquid feed time, a predetermined amount of the liquefied gas is sent during the liquid feed stop. Since the liquid container 13 may be supplied, a small capacity pump can be used as the liquefied gas pump 12. For example, when 1 kg of liquefied gas is sent to the user in a 60-second cycle with a liquid feed time of 10 seconds and a liquid feed stop time of 50 seconds, or when the liquefied gas is sent directly to the user with the liquefied gas pump 12 Since it is necessary to feed 1 kg in 10 seconds, it is necessary to use a liquefied gas pump having a capacity of 6 kg per minute.

  On the other hand, when supplying 1 kg of liquefied gas to the liquid sending container 13 in 50 seconds of the liquid sending stop time, 1 kg in 50 seconds is used, so a liquefied gas pump having a capacity of 1.2 kg per minute is used. It is possible to use a liquefied gas pump having a capacity of 2 kg per minute even if a sufficient margin is provided.

  As a result, the cost required for the liquefied gas pump can be greatly reduced, and the diameter of the piping around the pump can be reduced, so that the cost of the entire apparatus can be greatly reduced. Furthermore, since the amount of heat penetration can be reduced as the size and diameter are reduced, the evaporation loss of the liquefied gas can be reduced.

  It should be noted that, for each device including the liquid supply container 13, the liquefied gas evaporator 14, the temperature controller 16, and the refrigerator 18, what is conventionally used for supplying this kind of liquefied gas is used. It can be arbitrarily selected and used according to conditions such as the amount and the type of liquefied gas. Further, the control of the liquefied gas feeding amount can be performed by measuring the liquid level height.

  Further, as the pressurized gas for keeping the inside of the liquefied gas container 11 and the liquid sending container 13 at a predetermined pressure, an appropriate gas outside the system can be used, and the liquefied gas container 11 evaporates for self-pressurization. There is no need to prepare a pressurizing gas even when a liquefied gas source is provided or when the liquefied gas source is a liquefied gas pipe, and in this case, the supply-side back pressure valve 27 is also unnecessary. Further, when the liquid feeding time is short and the liquefied gas pump 12 can be stopped, the circulation path 17 can be omitted.

  In addition, even when liquid gas is sent intermittently to the user and the liquid supply stop time is shorter than the liquid supply time to the user, the liquid supply container 13 is divided into two systems. By supplying liquefied gas to the other one system of liquid supply containers while one system is supplying liquid to the destination, liquid can be alternately sent to the destination, so that the capacity of the liquefied gas pump 12 can be reduced. Is possible.

It is a systematic diagram which shows an example of the liquefied gas liquid feeding apparatus for enforcing the liquefied gas liquid feeding method of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Liquefied gas container, 11a, 11b ... Container valve, 12 ... Liquefied gas pump, 12a ... Motor, 13 ... Liquid supply container, 14 ... Liquefied gas evaporator, 15 ... Weigh scale (load cell), 16 ... Temperature controller, DESCRIPTION OF SYMBOLS 17 ... Circulation path, 18 ... Refrigerator, 19 ... Heater, 20 ... Buffer tank, 21 ... Liquefied gas supply path, 22 ... Pressurization path, 23, 24, 25, 26 ... Manual valve, 27 ... Supply side back pressure valve 28 ... circulation side back pressure valve, 29 ... liquid feeding side pressure reducing valve, 30 ... pressure raising side pressure reducing valve, 31 ... pressure adjusting valve, 32 ... pressure indicating controller, 33 ... liquid feeding valve, 34 ... circulation valve, 35 ... Liquefied gas supply valve, 36 ... Pressurization source supply path, 37 ... Pressurization path for liquid feeding, 38 ... Liquid feeding path, 39 ... Depressurization adjusting valve

Claims (4)

In the liquefied gas delivery method that intermittently delivers the liquefied gas to the user,
When the liquid supply to the user is stopped, the liquefied gas from the liquefied gas source is pressurized by the liquefied gas pump and supplied to the liquid supply container .
A part of the pressurized liquefied gas is vaporized, and the vaporized gas is maintained at a preset pressure.
Introducing the vaporized gas into the liquid delivery container when performing liquid delivery to a use destination, and sending the liquefied gas stored in the liquid delivery container to the use destination,
A method for feeding a liquefied gas, wherein the supply of the liquefied gas from the liquefied gas source to the liquid feeding container is stopped. A back pressure valve that branches the liquefied gas to be vaporized from between the liquefied gas pump and the liquid supply container and opens when the pressure on the liquefied gas pump side is equal to or higher than a preset pressure downstream from the branch position. The method for feeding a liquefied gas according to claim 1, wherein: The time when the liquefied gas from the liquefied gas source is pressurized by the liquefied gas pump and supplied to the liquid feeding container is longer than the time when the supply of the liquefied gas from the liquefied gas source to the liquid feeding container is stopped. A method for feeding a liquefied gas according to claim 1 or 2. The method for feeding a liquefied gas according to any one of claims 1 to 3, wherein the liquid feed amount of the liquefied gas to the use destination is controlled by measuring the weight of the liquid feeding container.

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