Recovered gas amount measuring device, gas recovery device and gas recovery method

Abstract

To provide a technique capable of accurately measuring a recovery amount of object gas when recovering the object gas such as helium gas (or liquefied gas thereof) from a user who uses the object gas.SOLUTION: A recovered gas amount measuring device 20 measures a recovery amount of object gas when the object gas is recovered through a recovery pipe 11. The recovered gas amount measuring device 20 includes a thermometer 21, a purity meter 22, a flowmeter 23 and a calculation device 24. The thermometer 21 measures a temperature of the object gas flowing in the recovery pipe 11. The purity meter 22 measures purity of the object gas flowing in the recovery pipe 11. The flowmeter 23 measures a flow rate of the object gas flowing in the recovery pipe 11. The calculation device 24 calculates a recovery amount of the object gas on the basis of the measured temperature, purity and flow rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas recovery device and a gas recovery method for recovering a target gas such as helium gas evaporated from liquid helium, and also to a recovered gas amount measuring device for measuring the amount of the target gas recovered when the target gas is recovered. [Background technology]

[0002] Conventionally, in MRI (Magnetic Resonance Imaging) and NMR (Nuclear Magnetic Resonance) devices, superconducting coils are cooled to cryogenic temperatures to maintain their superconducting state. Liquid helium is used for this cooling. Specifically, the superconducting coils are placed in liquid helium contained in the cryostat of the MRI or NMR device.

[0003] In MRI and NMR devices, liquid helium in a cryostat gradually evaporates. Helium gas is a rare and expensive gas. Therefore, it is desirable to recover and reuse the evaporated helium gas in the MRI and NMR devices. For example, it is desirable to re-liquefy the recovered helium gas and reuse it in the MRI and NMR devices. A conventional technique for recovering helium gas is described, for example, in Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-080966 Summary of the Invention [Problem to be solved by the invention]

[0005] Regarding the recovery of helium gas as described above, it is assumed that users (hereinafter simply referred to as "users") who use liquefied helium in MRI devices and the like will request a separate recovery party to recover the evaporated helium gas. In this case, the following problems arise. Note that users are legal entities such as companies, research institutes, and medical institutions, and the recovery parties are also legal entities.

[0006] A user requests a collector to collect helium gas that has evaporated in a device that uses liquefied helium, such as an MRI device, for example, to re-liquefy the helium gas. At this time, the user informs the collector of the amount of helium to be collected. Based on the user's request, the collector collects the helium gas from the user and, for example, re-liquefies the collected helium gas. The re-liquefied liquefied helium is stored in a storage tank that stores liquefied helium. Note that the storage tank already stores liquid helium other than the newly collected liquefied helium.

[0007] After recovering or re-liquefying the helium gas as described above, the recoverer may deliver the liquefied helium to the user based on the amount of helium communicated by the user as described above.

[0008] However, if the amount of helium communicated by the user differs from the amount actually recovered by the recoverer, the price of helium will differ significantly depending on the amount recovered, since helium is expensive. As a result, either the user or the recoverer will suffer a large loss. In particular, if the amount of helium communicated by the user is greater than the actual amount recovered, the recoverer will suffer a large loss despite having recovered and reliquefied the helium at the user's request.

[0009] Such problems can also arise when a recoverer recovers target gases other than helium gas (for example, rare gases such as neon and argon, or hydrogen gas) and delivers the liquefied gas to a user. Similar problems can also arise when a recoverer recovers a target gas (for example, helium gas, rare gas, hydrogen gas, etc.) whose actual amount is unknown from the user and purchases the recovered amount or returns to the user an amount of target gas substantially equal to the amount recovered.

[0010] The present invention has been made in light of the above-mentioned problems. That is, an object of the present invention is to provide a technology that can accurately measure the amount of target gas recovered when recovering the target gas, such as helium gas (or its liquefied form), from a user who uses the target gas. [Means for solving the problem]

[0011] A first aspect of the present invention is a recovered gas amount measuring device that measures the amount of recovered target gas when the target gas is recovered through a recovery pipe, a thermometer that measures the temperature of the target gas flowing through the recovery pipe; a purity meter that measures the purity of the target gas flowing through the recovery pipe; a flow meter that measures the flow rate of the target gas flowing through the recovery pipe; and a calculation device that calculates the recovered amount of the target gas based on the measured temperature, purity, and flow rate.

[0012] A second aspect of the present invention is a gas recovery device, The collected gas amount measuring device described above; The recovery pipe; The downstream end of the recovery pipe is connected to a recovered gas container that stores the target gas that has passed through the flow meter.

[0013] A third aspect of the present invention is a gas recovery method using the above-mentioned recovered gas amount measuring device, connecting the upstream end of the recovery pipe to a gas storage body in which the target gas is stored; When the target gas is stored in the collected gas storage body through the collection pipe into the collected gas storage body, the collected gas amount measuring device measures the collected amount of the target gas. [Effects of the Invention]

[0014] According to the present invention described above, when recovering a target gas from a user who uses the target gas or its liquefied gas, the amount of the target gas recovered can be accurately measured. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a configuration diagram of a gas recovery device according to an embodiment of the present invention. [Figure 2] 1 is a block diagram of a collected gas amount measuring device according to an embodiment of the present invention. [Figure 3] 1 is a flowchart illustrating a gas recovery method according to an embodiment of the present invention. [Figures 4A-4E] 2 shows an example of a check valve configuration that can be used in the gas recovery device of FIG. 1 or for other applications. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described with reference to the drawings. In addition, common parts in the drawings are given the same reference numerals, and duplicated explanations will be omitted.

[0017] FIG. 1 is a configuration diagram of a gas recovery device 10 according to an embodiment of the present invention. In this embodiment, the gas recovery device 10 is a device for recovering helium gas evaporated in a liquefied helium-utilizing device 1, such as an MRI device or an NMR device. That is, a user of liquefied helium (a legal entity such as a company, research institute, or medical institution) requests a recovery party (e.g., a legal entity) to recover the helium gas evaporated in the liquefied helium-utilizing device 1. In this case, the recovery party can use the gas recovery device 10 to recover the requested helium gas. The gas recovery device 10 may be owned by the recovery party.

[0018] (Gas recovery device configuration) The gas recovery device 10 includes a recovery pipe 11 , a recovered gas container 12 , a recovered gas amount measuring device 20 , a temperature adjusting device 13 , and a check valve 30 .

[0019] <Recovery tube> The recovery pipe 11 receives and recovers helium gas that has evaporated from liquefied helium in the liquefied helium utilization apparatus 1. The upstream end of the recovery pipe 11 is airtightly connected to a gas accumulation body 1a in which the helium gas to be recovered is stored. This connection may be made via an appropriate pipe joint, valve, or the like. The gas accumulation body 1a may be a cryostat provided in the liquefied helium utilization apparatus 1 as in the example of FIG. 1, or may be a gas bag (pouch) that accumulates helium gas discharged from the liquefied helium utilization apparatus 1.

[0020] The gas accumulator 1a may be transported to the installation location of the gas recovery device 10 (recovery pipe 11) and connected to the upstream end of the recovery pipe 11. When the gas accumulator 1a is provided in the liquefied helium utilization device 1 as shown in FIG. 1, the liquefied helium utilization device 1 may be transported to the installation location of the gas recovery device 10.

[0021] The recovery pipe 11 receives helium gas from the gas storage body 1a to which its upstream end is connected and flows it downstream.

[0022] <Gas recovery container> The recovered gas container 12 is connected to the downstream end of the recovery pipe 11. The recovered gas container 12 contains and stores the helium gas recovered through the recovery pipe 11. The recovered gas container 12 may be, for example, a gas bag, a gas cylinder, or a gas tank. After the helium gas has been recovered from the gas storage container 1a through the recovery pipe 11 and into the recovered gas container 12, the helium gas in the recovered gas container 12 is supplied to a re-liquefaction facility, where it is re-liquefied and sent to a liquefied helium storage container (e.g., a tank). The liquefied helium in the storage container is then returned to the user (e.g., the above-mentioned gas storage container 1a) through appropriate piping or the like. Note that this storage container already stores liquid helium other than the newly stored liquefied helium.

[0023] <Pressure device for flowing helium gas into the recovered gas container> A pressurizing device 2 may be provided to allow the helium gas in the gas accumulation body 1a to continuously flow into the recovered gas container 12 through the recovery pipe 11. The pressurizing device 2 pressurizes the helium gas from the gas accumulation body 1a so that it flows downstream of the recovery pipe 11.

[0024] 1, the pressurizing device 2 is provided in a liquefied helium utilization device 1 (for example, an MRI device). In this case, the pressurizing device 2 flows helium gas from a portion of the interior of the liquefied helium utilization device 1 (for example, cryostat 1a or a region communicating with cryostat 1a) that is at a temperature lower than room temperature into a heating device (for example, a heat exchanger), and returns the helium gas that has been heated to room temperature and pressurized by this heating device back into the interior of the liquefied helium utilization device (for example, a region communicating with cryostat 1a). In this way, the helium gas inside the liquefied helium utilization device 1 may be pressurized.

[0025] Instead of the pressurizing device 2 provided in the liquefied helium utilization device 1, a pressurizing device may be provided in the gas recovery device 10. The pressurizing device may be provided somewhere along the recovery pipe 11 (for example, at the downstream end of the recovery pipe 11). The pressurizing device may be a gas compressor that compresses helium gas in the recovery pipe 11 and sends it downstream.

[0026] <Recovered gas volume measuring device> The recovered gas amount measuring device 20 measures the amount of helium gas recovered from the gas accumulation body 1a through the recovery pipe 11 to the recovered gas container 12. The recovered gas amount measuring device 20 includes a thermometer 21, a purity meter 22, a flow meter 23, and a computing device 24.

[0027] Thermometer 21 measures the temperature of the helium gas flowing through recovery pipe 11. Thermometer 21 inputs the measured temperature to calculation device 24. In this embodiment, thermometer 21 measures the temperature of the helium gas in real time (every moment), and inputs the measured temperature in real time (every moment) to calculation device 24. Thermometer 21 may measure the temperature inside recovery pipe 11 as the temperature of the helium gas.

[0028] The thermometer 21 is provided downstream of the temperature adjustment device 13 (heat medium container 13a described below) and upstream of the flowmeter 23. In this embodiment, the thermometer 21 is located upstream of the flowmeter 23 in the recovery pipe 11, within a vicinity range where the distance from the flowmeter 23 is equal to or less than a predetermined value. Here, the vicinity range means that the position of the thermometer 21 is close to the flowmeter 23 to the extent that the actual temperature of the helium gas flowing into the flowmeter 23 and the temperature measured by the thermometer 21 are substantially the same. For example, the thermometer 21 may be provided upstream of the flowmeter 23 in the recovery pipe 11, immediately before the flowmeter 23, or at the inlet of the flowmeter (casing 23a described below).

[0029] Purity meter 22 measures the purity of the helium gas flowing through recovery pipe 11. In this embodiment, purity meter 22 measures the purity of the helium gas in real time (every moment), and inputs the measured purity to calculation device 24 in real time (every moment).

[0030] Purity meter 22 may be, for example, an ultrasonic purity meter (gas concentration meter). In this case, purity meter 22 may measure the propagation time of the ultrasonic waves in the helium gas by transmitting and receiving ultrasonic waves into the helium gas at a predetermined local location in recovery pipe 11, determine the propagation velocity of the ultrasonic waves based on this propagation time, and calculate the purity (concentration) of the helium gas based on the determined propagation velocity.

[0031] At this time, the ultrasonic purity meter 22 may calculate the purity (concentration) of the helium gas based not only on the propagation speed but also on the temperature of the helium gas flowing inside the recovery pipe 11. This temperature may be the temperature at the position inside the recovery pipe 11 where the ultrasonic waves are propagated. In other words, the purity meter 22 may also have a temperature sensor (not shown) that measures this temperature. Note that the purity meter 22 may use the temperature measured by the thermometer 21 instead of the temperature measured by this temperature sensor.

[0032] Flow meter 23 measures the flow rate of helium gas flowing through recovery pipe 11. Flow meter 23 is provided at a location midway through recovery pipe 11. That is, the helium gas flowing through recovery pipe 11 passes through flow meter 23 before reaching recovery gas container 12.

[0033] The calculation device 24 calculates the amount of recovered helium gas based on the temperature of the helium gas measured by the thermometer 21, the purity of the helium gas measured by the purity meter 22, and the flow rate of the helium gas measured by the flow meter 23.

[0034] This recovery amount indicates the amount of pure (100% pure) helium gas excluding components other than helium. For example, the recovery amount may be the volume or mass of pure helium gas at a specified temperature and pressure.

[0035] The flow meter 23 may be a positive displacement flow meter 23. This positive displacement flow meter 23 has a casing 23a through which helium gas passes, and outputs a gas passage signal to the computing device 24 each time a set volume of helium gas passes through the inside of the casing 23a. Here, the set volume may be constant. The positive displacement flow meter 23 may be a membrane type, but is not limited to this. For example, the positive displacement flow meter 23 may be a rotary vane type, a reciprocating piston type, or a Roots type. The configuration of the positive displacement flow meter 23 may be a known one, and therefore a detailed description thereof will be omitted.

[0036] The positive displacement flowmeter 23 outputs a gas passage signal whenever a time ranging from one second to several seconds (for example, about two seconds) has elapsed. However, in the final stage of helium gas recovery (i.e., the final stage of a measurement period described below), the flow rate of helium gas from the gas accumulation body 1a1a to the recovery pipe 11 decreases, and the positive displacement flowmeter 23 may output a gas passage signal whenever a longer time has elapsed.

[0037] 2 is a block diagram showing the configuration of the arithmetic device 24. When the flow meter 23 is the above-mentioned positive displacement flow meter, the arithmetic device 24 has a passing amount calculation unit 24a and an integrating unit 24b.

[0038] Each time the passing rate calculation unit 24a receives a gas passing signal from the above-mentioned positive displacement flowmeter 23, it calculates the passing rate of the helium gas based on the above-mentioned set volume, the temperature measured by the thermometer 21, and the purity measured by the purity meter 22. Here, the temperature measured by the thermometer 21 and the purity measured by the purity meter 22 may be the temperature measured in real time by the thermometer 21 and input to the passing rate calculation unit 24a in real time, and the purity measured in real time by the purity meter 22 and input to the passing rate calculation unit 24a in real time, respectively.

[0039] Similarly to the recovery amount, the throughput refers to the amount of pure (100% pure) helium gas excluding components other than helium. For example, the throughput may be the volume or mass of pure helium gas at a predetermined temperature and pressure.

[0040] The passing rate calculated by the passing rate calculation unit 24a may be expressed by a function Q(T, P). This Q(T, P) is a function with temperature T and purity P as variables, and may reflect the above-mentioned set field. Every time the passing rate calculation unit 24a receives a gas passing signal from the positive displacement flowmeter 23, the passing rate calculation unit 24a calculates the passing rate Q(T, P) by taking the temperature input in real time by the thermometer 21 as T and the purity input in real time by the purity meter 22 as P and applying T and P to Q(T, P).

[0041] Q(T, P) may be expressed by the following equation (1) as an example, but is not limited to this. Q(T,P) = C×T×P×V (1) where C is a constant and V is the set volume as described above.

[0042] The integrating unit 24b calculates the recovery amount by integrating the passing amounts repeatedly calculated by the arithmetic unit 24 as described above. That is, the integrating unit 24b calculates the recovery amount as the integrated value (total) of the repeatedly calculated passing amounts. This recovery amount may indicate the total amount of helium gas recovered through the recovery pipe 11.

[0043] As shown in FIG. 2, the calculation device 24 may further include a conversion unit 24c, a storage unit 24d, and an output unit 24e.

[0044] The conversion unit 24c may be provided when the volume of pure helium gas is used as described above. The conversion unit 24c converts the recovered amount calculated by the calculation device 24 into a predetermined conversion value. This conversion value may be the amount (e.g., volume) of liquefied helium obtained by liquefying the recovered amount of helium gas.

[0045] The storage unit 24d stores the recovery amount calculated by the accumulating unit 24b. That is, the accumulating unit 24b stores the calculated recovery amount in the storage unit 24d. The storage unit 24d also stores the converted value calculated by the converting unit 24c. That is, the converting unit 24c stores the calculated converted value in the storage unit 24d.

[0046] The output unit 24e outputs one or both of the recovery amount calculated by the accumulating unit 24b and the converted value calculated by the conversion unit 24c (for example, the recovery amount and converted value stored in the memory unit 24d). This output may be displayed on a display screen. In this case, the output unit 24e is a display. The output by the output unit 24e may also be transmitted to a predetermined terminal (for example, transmitted via a network). In this case, the output unit 24e is a transmitting device. The output by the output unit 24e may also be printed on paper. In this case, the output unit 24e is a printer.

[0047] <Temperature control device> The temperature controller 13 is provided in the recovery pipe 11 upstream of the flowmeter 23 and heats the helium gas passing through it so that its temperature reaches a set value. This set value is, for example, 15°C. The set value is not limited to this. The set value may be another temperature at which the positive displacement flowmeter 23 operates normally. For example, the set value may be any constant temperature between 0°C and 25°C.

[0048] The temperature adjustment device 13 may be configured as a heat exchanger. In this case, the temperature adjustment device 13 includes, for example, a heat medium container 13a, a heater 13b, and a heater control device 13c.

[0049] Heat medium container 13a accommodates heat medium 13a1 therein. This heat medium 13a1 may be a liquid (e.g., water). Recovery pipe 11 is provided so as to pass through heat medium 13a1 in heat medium container 13a. As a result, heat medium 13a1 applies heat to the helium gas in recovery pipe 11 through the outer wall of recovery pipe 11.

[0050] The heater 13b is disposed in the heat medium 13a1 in the heat medium container 13a, and heats the heat medium 13a1 by the supplied electric power. The heater 13b may be made of an electric heating wire.

[0051] Heater control device 13c measures the temperature of the helium gas at a position downstream of heat medium container 13a in recovery pipe 11, and controls the power supplied to heater 13b based on the measured temperature so that the temperature of the helium gas that has passed through temperature adjustment device 13 becomes the set value. Heater control device 13c may be configured to include heater thermometer 13c1 and power control unit 13c2.

[0052] Heater thermometer 13c1 is provided at a position downstream of heat medium container 13a in recovery pipe 11. Heater thermometer 13c1 measures the temperature of the helium gas in recovery pipe 11 at this downstream position. Heater thermometer 13c1 inputs the measured temperature to the heater 13b control unit.

[0053] Based on the temperature input from heater thermometer 13c1, power control unit 13c2 controls the power supplied to heater 13b so that the temperature of the helium gas passing through temperature adjustment device 13 (e.g., the temperature measured by heater thermometer 13c1) becomes the above-mentioned set value. This control may be, for example, control of turning on and off the power supply to heater 13b, control of increasing or decreasing the power to heater 13b, or a combination of both. Note that power control unit 13c2 may use the temperature measured by thermometer 21 described above instead of the temperature measured by heater thermometer 13c1. In this case, heater thermometer 13c1 is omitted.

[0054] <Check valve> The check valve 30 is provided in the recovery pipe 11 downstream of the flow meter 23 and upstream of the recovered gas container 12. The check valve 30 prevents backflow of the helium gas passing through. That is, the check valve 30 is configured to allow helium gas to pass through the check valve 30 from the upstream side to the downstream side of the recovery pipe 11, but to prevent helium gas from passing through the check valve 30 from the downstream side to the upstream side of the recovery pipe 11. An example configuration of the check valve 30 will be described later.

[0055] (Gas recovery method) 3 is a flowchart showing a gas recovery method according to an embodiment of the present invention. This gas recovery method is carried out using recovered gas amount measuring device 20 equipped with the above-mentioned recovered gas amount measuring device 20. A user of liquefied helium may request a recovery party (e.g., a corporation) to recover helium gas resulting from evaporation of liquefied helium in liquefied helium utilization device 1, and in response to this request, the recovery party may carry out the gas recovery method according to this embodiment. This gas recovery method has steps S1 to S4.

[0056] In step S1, the upstream end of the recovery pipe 11 is connected via an appropriate pipe joint or the like to a gas storage body 1a (e.g., a cryostat 1a) provided in the liquefied helium utilization device 1, or to a gas storage body (e.g., a gas bag) in which helium gas extracted from the liquefied helium utilization device 1 is stored.

[0057] In step S1, each part of the collected gas amount measuring device 20 (collected gas amount measuring device 20, temperature adjusting device 13, etc.) is put into an operating state.

[0058] In step S2, helium gas is caused to flow from the gas accumulator 1a into the recovery pipe 11. For example, step S2 may be started by opening an on-off valve (not shown) provided at the connection portion of the gas accumulator 1a with the upstream end of the recovery pipe 11 and opening an on-off valve (not shown) provided at the upstream end of the recovery pipe 11. At this time, the helium gas may be pressurized by the above-mentioned pressurizing device to flow downstream of the recovery pipe 11 so that the helium gas flows through the recovery pipe 11 into the recovered gas container 12. This pressurization may be performed, for example, at the upstream end of the recovery pipe 11 or on the gas accumulator 1a side (e.g., the liquefied helium utilization device 1).

[0059] In step S3, the total amount of helium gas recovered from gas accumulation body 1a over the measurement period from the start to the end of step S2 is measured as the recovered amount by recovered gas amount measuring device 20. The end of the measurement period may be the time when helium gas substantially stops flowing from gas accumulation body 1a into recovery pipe 11, for example, the time when positive displacement flow meter 23 stops outputting the above-mentioned gas passage signal (for a sufficiently long predetermined time).

[0060] During the measurement period, the temperature adjusting device 13 of the collected gas amount measuring device 20 operates in the same manner as described above, and therefore a detailed description thereof will be omitted here.

[0061] In this embodiment, in step S3, over the above-mentioned measurement period, recovered gas amount measuring device 20 measures, as the recovered amount, the total amount (integrated value) of helium gas that has passed through volumetric flowmeter 23. At this time, recovered gas amount measuring device 20 may further convert the recovered amount into a predetermined conversion value as described above.

[0062] After completing step S3, in step S4, the collector performs the following steps (1) to (3). (1) The collected amount and the converted value calculated in step S3 are output from the output unit 24e, so that the collector and the user can confirm the collected amount and the converted value. (2) The helium gas recovered in the recovered gas container 12 is re-liquefied by a re-liquefaction facility (not shown) and supplied to a liquefied helium storage container. (3) If the conversion value indicates the amount of liquid helium, the amount of liquid helium indicated by the conversion value will be delivered to the user, or the amount of liquid helium that is increased or decreased by a specified amount from the amount indicated by the conversion value will be delivered to the user in accordance with the transaction between the user and the collector.

[0063] The recoverer may omit the above step (3) and purchase the recovered amount of helium gas from the user.

[0064] (Effects of the gas recovery device according to the embodiment) The gas recovery device 10 of this embodiment provides the following effects (A) to (E).

[0065] (A) When helium gas evaporated from a user of liquefied helium gas is recovered through recovery pipe 11, the temperature, purity, and flow rate of the helium gas flowing through recovery pipe 11 are measured, and the amount of recovered helium gas (recovered amount) is calculated based on the measured temperature, purity, and flow rate. In this way, the recovered amount is calculated based on the temperature, purity, and flow rate of the helium gas, making it possible to accurately measure the recovered amount of helium gas.

[0066] In this way, the amount of helium gas actually recovered through the recovery pipe 11 is measured during the recovery process. Therefore, based on this recovered amount, the recovery party and the user can conduct fair transactions for expensive helium. For example, when a recovery party recovers helium gas from a user and delivers to the user an amount of liquefied helium equivalent to the amount recovered, the transaction can be conducted based on the accurately measured recovered amount. This prevents the recovery party from incurring losses by delivering to the user an amount of liquefied helium that is greater than the amount equivalent to the amount recovered.

[0067] (B) Furthermore, the following problem can be solved: Problem: During the recovery of helium gas, the temperature or purity of the helium gas passing through the flow meter 23 tends to fluctuate.

[0068] Therefore, in this embodiment, flowmeter 23 is a positive displacement flowmeter 23 that outputs a gas passing signal each time a set volume of helium passes through casing 23a, and passing amount calculation unit 24a calculates the passing amount of helium gas based on the set volume, the measured temperature, and the measured purity each time it receives a gas passing signal. As a result, the passing amount is calculated based on the newly measured temperature and purity (e.g., in real time) each time a set volume of helium passes through casing 23a, so that the passing amount of helium gas can be accurately measured even if the temperature or purity of the helium gas fluctuates. Furthermore, by integrating the amount of passing gas repeatedly calculated in this manner, the total amount of helium gas received through the recovery pipe 11 is determined as the amount of recovered helium gas. Therefore, even if the temperature or purity of the helium gas fluctuates during recovery, the amount of recovered helium gas can be accurately measured.

[0069] (C) Thermometer 21 is located within a vicinity of flowmeter 23, within a predetermined distance along recovery pipe 11 from flowmeter 23. Therefore, the measured temperature can be regarded as the temperature of the helium gas that actually flows into volumetric flowmeter 23. This allows for more accurate measurement of the amount of recovered helium gas.

[0070] (D) The conversion unit 24c converts the calculated recovered amount into a predetermined conversion value. This conversion value is the amount of liquid obtained by liquefying the recovered amount of helium gas. Therefore, when the recoverer delivers an amount of liquefied helium corresponding to the recovered amount to the user, the amount of liquefied helium to be delivered can be easily determined.

[0071] (E) It can also solve the following problem: Problem: When the downstream end of the recovery pipe 11 is connected to the liquefied helium utilization device 1 to recover helium gas from the liquefied helium utilization device 1, liquefied helium remaining in the gas accumulation body 1a of the liquefied helium utilization device 1 can cause helium gas that is extremely cold compared to room temperature to flow from the liquefied helium utilization device 1 (gas accumulation body 1a) into the recovery pipe 11. If such extremely cold helium gas flows into the positive displacement flowmeter 23, the positive displacement flowmeter 23 may not function properly. That is, the positive displacement flowmeter 23 may freeze and stop working or may be damaged. For example, if the positive displacement flowmeter 23 is a membrane type, the operating membrane may crack.

[0072] To prevent such problems, temperature regulator 13 is provided upstream of flowmeter 23. Temperature regulator 13 heats the helium gas passing through it so that the temperature of the helium gas reaches a set value (for example, 15°C). This prevents extremely low-temperature helium gas from flowing into positive displacement flowmeter 23. As a result, the reliability of measurements by positive displacement flowmeter 23 is improved, and malfunctions or damage to positive displacement flowmeter 23 caused by extremely low-temperature helium gas can be prevented.

[0073] (Embodiment of check valve) An embodiment of the check valve 30 described above will be described with reference to Figures 4A to 4E. Figure 4A shows a cross section of the check valve 30 taken along a plane including the central axis C of the check valve 30. Figure 4B is a cross section taken along line 4B-4B of Figure 4A. Figure 4C is a cross section taken along line 4C-4C of Figure 4A. The check valve 30 has a main body 31, a spherical body 32, an inlet-side member 33, and an outlet-side member 34.

[0074] The main body 31 has an inner peripheral surface 31a that surrounds the central axis C. This inner peripheral surface 31a defines an internal space 31b of the main body 31. The main body 31 is, for example, a cylindrical member. The internal space 31b penetrates the main body 31 in a direction parallel to the central axis C (hereinafter simply referred to as the axial direction). The inner peripheral surface 31a of the main body 31 is formed with internal threads 31a1 at both axial end portions of the main body 31. The main body 31 may be made of resin (for example, transparent acrylic), but may also be made of other materials.

[0075] The sphere 32 is disposed in the internal space 31b of the main body 31 so as to be able to move freely within the internal space 31b. The sphere 32 functions as a valve body. The sphere 32 may be made of rubber or resin, but may also be made of other materials as long as the sphere 32 does not interfere with its function as a valve body.

[0076] The inlet-side member 33 is attached to the upstream end, which is one axial end of the main body 31. An inlet hole 33a penetrates the inlet-side member 33 in the axial direction, allowing helium gas to flow into the internal space 31b of the main body 31. The inlet-side member 33 has a reduced-diameter portion 33b on the main body 31 side, and a male thread 33b1 is formed on the outer circumferential surface of this reduced-diameter portion 33b. The inlet-side member 33 is removably attached to the main body 31 by threading this male thread 33b1 into a female thread 31a1 at the upstream end of the main body 31.

[0077] The inlet-side member 33 also has a flange 33c that is connected to the reduced-diameter portion 33b from the side opposite the main body 31. The flange 33c has a cross-sectional dimension taken along a plane perpendicular to the central axis C that is larger than that of the reduced-diameter portion 33b. The flange 33c may be cylindrical. An O-ring 35 is sandwiched between the flange 33c and the axial end face of the main body 31. This allows the inlet-side member 33 to be attached to the main body 31 in an airtight manner.

[0078] A circular opening 33a1 of the inlet hole 33a is formed in the downstream end surface 33d of the inlet-side member 33 (reduced diameter portion 33b). The radius of this circular opening 33a1 is smaller than the radius of the sphere 32.

[0079] The outflow-side member 34 is attached to the downstream end of the main body 31. An outflow hole 34a penetrates the outflow-side member 34 in the axial direction, allowing helium gas to flow out of the internal space 31b of the main body 31. The outflow-side member 34 has a reduced-diameter portion 34b on the main body 31 side, and a male thread 34b1 is formed on the outer circumferential surface of this reduced-diameter portion 33b. The male thread 34b1 is threadedly engaged with the female thread 31a1 at the downstream end of the main body 31, thereby removably attaching the outflow-side member 34 to the main body 31.

[0080] The outflow-side member 34 also has a flange 34c that is connected to the reduced-diameter portion 33b from the side opposite the main body 31. The cross-sectional dimension of the flange 34c, taken along a plane perpendicular to the central axis C, is larger than that of the reduced-diameter portion 34b. The flange 34c may be cylindrical. An O-ring 35 is sandwiched between the flange 34c and the axial end face of the main body 31. This allows the outflow-side member 34 to be attached to the main body 31 in an airtight manner.

[0081] A circular opening 34a1 of the outlet hole 34a is formed in the downstream end surface 34d of the outlet side member 34. The radius of this circular opening 34a1 is smaller than the radius of the sphere 32.

[0082] A cutout 34e is formed in the downstream end face 34d relative to the circular opening 34a1. The cutout 34e extends outward (i.e., away from the central axis C) from a portion of the outer edge of the circular opening 34a1. The cutout 34e has a predetermined depth from the downstream end face 33d. As will be described later, even if a portion of the sphere 32 enters the circular opening 33a1 of the outflow-side member 34 due to the flow of helium gas, the helium gas in the internal space 31b can flow into the outflow hole 34a through the cutout 34e (FIG. 4E).

[0083] In Figure 4A, the bottom side of the figure is the vertically downward direction. As shown in Figure 4A, the check valve 30 is preferably used by being disposed so that the central axis C faces vertically and the downstream side is the downward direction.

[0084] Check valve 30 is provided midway along recovery pipe 11. That is, check valve 30 allows helium gas flowing from upstream portion 11a of recovery pipe 11 to flow through inlet hole 33a, internal space 31b, and outlet hole 34a in that order, and then to flow into downstream portion 11b of recovery pipe 11. The downstream end of upstream portion 11a is airtightly connected to inlet-side member 33 by appropriate means (for example, welding), and the upstream end of downstream portion 11b is airtightly connected to outlet-side member 34 by appropriate means (for example, welding).

[0085] <Effects of check valves> When helium gas passes through check valve 30 from the downstream side to the upstream side of recovery pipe 11, sphere 32 is pushed downstream by the flow of helium gas in internal space 31b as shown in Figure 4A, and does not block circular opening 33a1. Therefore, helium gas from upstream portion 11a passes through check valve 30 and flows to downstream portion 11b.

[0086] On the other hand, when helium gas attempts to flow back through the check valve 30, as shown in FIG. 4D , the backflow causes part of the sphere 32 to enter the inlet hole 33a and block the inlet hole 33a, thereby preventing the backflow. Note that if the inlet-side member 33 is disposed vertically below the outlet-side member 34, gravity also acts on the sphere 32 toward the inlet hole 33a. This allows the sphere 32 to move more smoothly toward the inlet hole 33a and block the inlet hole 33a.

[0087] Furthermore, when helium gas passes through check valve 30 from the downstream side to the upstream side of recovery pipe 11, sphere 32 may be pushed by the flow of helium gas and partly enter circular opening 34a1 (outflow hole 34a), as shown in Fig. 4E. Even in this case, helium gas can flow from internal space 31b to outflow hole 34a and downstream portion 11b through the above-mentioned cutout portion 34e provided in circular opening 34a1.

[0088] Furthermore, the inlet-side member 33 is attached to the main body 31 by threading its male thread 33b1 into the female thread 31a1 of the main body 31, and therefore can be easily removed from the main body 31. The same is true for the outlet-side member 34. Therefore, maintenance of the main body 31 can be easily performed. For example, the inlet-side member 33, the outlet-side member 34, or the sphere 32 can be easily replaced, and the inner circumferential surface 31a of the main body 31 can be easily cleaned, if necessary.

[0089] The check valve 30 of this configuration example may be provided in the recovery pipe 11 of the gas recovery device 10 described above, but may also be provided at an intermediate location in a pipe through which gas flows in another device. In this case, in the above description of the embodiment of the check valve 30, the recovery pipe 11 is replaced with a pipe, and the helium gas is replaced with a gas, and the embodiment of the check valve 30 is applied to the other device. Another object of the present application is to provide such a check valve 30.

[0090] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical concept of the present invention. For example, the gas recovery device 10, the recovered gas amount measuring device 20, and the check valve 30 according to the embodiments of the present invention do not have to have all of the above-described features, and may have only some of the above-described features. Furthermore, the gas recovery device 10, the recovered gas amount measuring device 20, and the check valve 30 according to the embodiments of the present invention do not have to achieve all of the above-described effects, and may achieve only some of the effects.

[0091] Furthermore, any one of the following modified examples 1 to 3 may be adopted alone, or any combination of two or more of modified examples 1 to 3 may be adopted. In this case, the points not described below are the same as those described above.

[0092] (Change example 1) The conversion unit 24c may be omitted. In this case, the recovery amount calculated by the calculation device 24 (for example, the integrating unit 24b) may be the volume of liquefied helium obtained by liquefying pure helium gas.

[0093] (Change example 2) In the above description, the user is a user of liquefied helium, but the user may also be a user of helium gas. In this case, the collector may collect helium gas from the user and deliver helium gas of a predetermined purity to the user.

[0094] (Change example 3) In the above-described embodiment and modified example 2, the target gas recovered by the recovered gas amount measuring device according to the present invention is helium gas, but it may be another gas (for example, a rare gas such as neon or argon, or hydrogen gas, etc.). In the latter case, in the above-described embodiment and modified example 2, helium gas is read as the target gas, and liquefied helium is read as a liquefied gas obtained by liquefying the target gas. [Explanation of symbols]

[0095] 1. Equipment using liquefied helium (MRI equipment, NMR equipment) 1a Gas storage body (cryostat) 2. Pressure device 10 Gas recovery device 11 Recovery pipe 12. Recovery gas container 13 Temperature control device 13a Heat medium container 13a1 Heat medium 13b Heater 13c Heater control device 13c1 Heater thermometer 13c2 Power control section 20. Recovered gas volume measuring device 21 Thermometer 22 Purity meter 23 Flowmeter (positive displacement flowmeter) 23a casing 24 Arithmetic unit 24a Passage amount calculation section 24b Integration section 24c conversion section 24d storage section 24e Output section 30 Check valve 31 Main Unit 31a Inner surface 31a1 female thread 31b Internal space 32 sphere 33 Inlet side member 33a Inflow hole 33a1 Circular opening 33b Reduced diameter part 33b1 Male thread 33c Tsubabe 33d Downstream end face 34 Outlet side member 34a Outflow hole 34a1 Circular opening 34b Reduced diameter part 33b1 Male thread 34c Tsubabe 34d Upstream end face 34e Notch 35 O-ring C center axis

Claims

1. A recovered gas amount measuring device that measures the amount of recovered target gas when the target gas is recovered through a recovery pipe, a thermometer that measures the temperature of the target gas flowing through the recovery pipe; a purity meter that measures the purity of the target gas flowing through the recovery pipe; a flow meter that measures the flow rate of the target gas flowing through the recovery pipe; a calculation device that calculates the recovery amount of the target gas based on the measured temperature, purity, and flow rate; Recovered gas volume measuring device.

2. the flow meter is a positive displacement flow meter that has a casing through which the target gas passes, and outputs a gas passing signal to the computing device every time a set volume of the target gas passes through the casing; The computing device a passing amount calculation unit that calculates the passing amount of the target gas based on the set volume, the temperature measured by the thermometer, and the purity measured by the purity meter each time the gas passing signal is received; an integrating unit that calculates the recovery amount by integrating the repeatedly calculated passing amount, The collected gas amount measuring device according to claim 1.

3. the thermometer measures the temperature of the target gas in real time and inputs the measured temperature to the passing amount calculation unit; the purity meter measures the purity of the target gas in real time and inputs the measured purity to the passing amount calculation unit; the passing amount calculation unit calculates the passing amount based on the set volume, the temperature input in real time from the thermometer, and the purity input in real time from the purity meter every time the gas passing signal is received. The collected gas amount measuring device according to claim 2.

4. the thermometer is provided in the recovery pipe at a position upstream of the flow meter; the upstream position is within a vicinity of the flow meter, the distance along the recovery pipe from the flow meter being within a predetermined value; The collected gas amount measuring device according to claim 3.

5. The thermometer is provided in the recovery pipe immediately before the flow meter or at the inlet of the flow meter. The collected gas amount measuring device according to claim 4.

6. the recovery volume is a volume of pure helium gas; A conversion unit converts the collected amount into a predetermined conversion value, The converted value is the amount of liquid obtained by liquefying the target gas in the amount recovered. The collected gas amount measuring device according to claim 1.

7. The target gas is helium gas. The collected gas amount measuring device according to claim 1.

8. The collected gas amount measuring device according to any one of claims 1 to 7, The recovery pipe; a recovered gas container connected to the downstream end of the recovery pipe and configured to store the target gas that has passed through the flow meter; Gas recovery device.

9. The target gas is a gas obtained by evaporation of a liquefied gas, a temperature control device provided in the recovery pipe upstream of the flow meter; The temperature control device heats the target gas passing through it so that the temperature of the target gas reaches a set value. The gas recovery device according to claim 8.

10. The temperature control device is a heat medium container that accommodates a heat medium therein, and in which a middle portion of the recovery pipe is disposed in the heat medium; a heater that heats the heat medium by supplied power; a heater control device that measures the temperature of the target gas at a position downstream of the heat medium container in the recovery pipe and controls the power supplied to the heater based on the measured temperature so that the temperature of the target gas becomes the set value. The gas recovery device according to claim 9.

11. a check valve provided in the recovery pipe downstream of the flow meter and upstream of the recovered gas container; The gas recovery device according to claim 8.

12. A gas recovery method using the recovered gas amount measuring device according to any one of claims 1 to 7, connecting the upstream end of the recovery pipe to a gas storage body in which the target gas is stored; When the target gas is stored in the collected gas storage body through the collection pipe into the collected gas storage body, the collected gas amount measuring device measures the collected amount of the target gas. Gas recovery method.

Images