JP2004091298A - Apparatus and method for recovering sulfur hexafluoride gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and method where an SF6 gas can be easily recovered by adopting a recovering means and method to efficiently transport the gas in a liquified state to a final disposal facility. <P>SOLUTION: A circulation system is formed, which comprises a liquefaction means of a sulfur hexafluoride gas, a liquefied sulfur hexafluoride recovering vessel, an exhausting means to exhaust a mixed gas of air with the sulfur hexafluoride gas resident in an upper part of the recovering vessel, a measuring means placed at the exhausting means to measure the air content in the exhausted mixed gas, a pressure adjusting means controlled on the basis of the air content measured with the measuring means, and a membrane separating means to separate a part of air from the exhausted mixed gas. A feeding means to feed the air-mixed sulfur hexafluoride gas is connected to the circulation system, and liquefied sulfur hexafluoride is recovered from the liquefied sulfur hexafluoride recovering vessel. <P>COPYRIGHT: (C)2004,JPO

Description

回収料金総額は、理論回収ガス量と、混入空気排出費用に基づいてなされる。
【００６０】
次に液化圧力制御演算ループ１０９について説明する液化器液化温度データ１２１が求められ、温度測定データとして記憶される。ＳＦ６純度初期測定１１４の結果１２３と共に、これらの諸データは、ＳＦ６液化圧力決定処理に使用される。これらのデータに基づいて、図５に示す制御圧力演算・循環回数制御１０４を参照して圧力制御信号１２５を出力する。
【００６１】
【発明の効果】
本発明にあっては、顧客サイトに設置されているＳＦ６ガス封入機器の容積を問わず、またＳＦ６ガス中に空気等の不純物が混入している場合にあってもＳＦ６ガス中に混入する空気の一部ずつを分離しながら、ＳＦ６ガスを繰り返し一部ずつ液化しているので、輸送効率を極限まで上げるシステムおよび方法を提供できる。またこのシステムおよび方法によれば、空気混入のＳＦ６／８９ガスの処理を低コストで行うことができ、これに伴って低コストによるＳＦ６ガス回収方法をサービスとして提供できるようになる。
【図面の簡単な説明】
【図１】本発明の実施例についての全体概略システム図。
【図２】本発明の実施例についての詳細システム図。
【図３】ガスバッグ集中回収装置の構成図。
【図４】制御圧力演算のための制御・運転ブロック図。
【図５】制御圧力演算・循環回数制御図。
【図６】制御コンピュータの処理内容を示す図。
【符号の説明】
２１…希薄ＳＦ６循環式液化回収装置、２２…制御システム、２３…液化ＳＦ６ガス回収システム、３１…回収装置入口弁、３２…制圧回収ライン自動弁、３３…真空回収自動弁（１）、３４…真空回収サージタンク（１）、３５…真空回収ポンプ、３６…真空回収サージタンク（２）、３７…真空回収ライン圧力調整自動弁、３８…真空回収自動弁（２）、３９…回収圧縮機、４２…液化器、４４…回収容器（ボンベ）（ボンベ８に対応）、４５…液相ライン弁、４６…ガス相ライン弁、４７…分析用弁、４９…制御コンピュータ、５０…圧力調整弁、５１…膜分離装置、５２…酸素濃度計、５４…液化ＳＦ６、５５…空気＋ＳＦ６ガスの混合ガス、５８…回収対象機器、またはガスバッグ回収装置、１００…循環回収系統（循環系）。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sulfur hexafluoride gas recovery apparatus and method for liquefying and recovering used sulfur hexafluoride gas from a mixed gas of sulfur hexafluoride gas, air, and the like, and a method for charging for the recovery processing.
[0002]
[Prior art]
Sulfur hexafluoride gas (hereinafter referred to as SF6 gas) sealed in equipment such as electric equipment installed at a customer site needs to be collected before periodic repair or disposal of the equipment.
SF6 gas is a gas having excellent electrical insulation properties, and is used as an electrical insulating gas for high-voltage equipment such as circuit breakers, transformers, and semiconductor manufacturing equipment, but has a high global warming potential (carbon dioxide gas). (More than 20,000 times), and its release to the atmosphere is regulated.
[0003]
Usually, as a method for recovering SF6 gas, the following two recovery methods are employed: gaseous recovery and liquefaction recovery.
・ Gas recovery
1) When each customer collects SF6 gas in each electric device installed in its own site, the gaseous collection device collects SF6 gas in a collection container at a pressure of 1.0 MPa or less.
Was.
2) When discarding the collected gas, the collection container is transported to a manufacturer of SF6 gas for disposal.
3) Gas collection container inner volume 1.0m³In the case of, the recovered gas capacity is about 9.7 Nm³, 63.6 kg.
4) 1.0m³Is about φ1.0m * 1.4m, and the installation area is 1.0m * 1.4m = 1.4m.²And the area efficiency is Nm³/ M²・ Kg / m²7.1 Nm³/ M²・ 45.2kg / m²It becomes.
[0004]
・ Liquefaction recovery
1) When each customer collects SF6 gas in each electric device installed in the company's site, the liquefaction and collection device collects the SF6 gas as a liquefied gas in a collection container or a collection gas cylinder.
2) When the collected gas is discarded, the collected gas is collected in a cylinder instead of a collection container, transported to a manufacturer of SF6 gas, and discarded.
3) The volume of the cylinder is usually 46.7 l and the fillable SF6 gas is 50 kg.
4) The dimensions of the cylinder are φ0.3m * 1.5mH, and the installation area is 0.3m * 0.3m = 0.09m². The area efficiency is 85.2 Nm as in the case of gas recovery.³/ M²・ 555.6kg / m²And an area efficiency about 12 times that of gas recovery can be obtained.
[0005]
In consideration of the volumetric efficiency in transporting, it is desirable to recover by liquefaction. However, if impurities such as air are contained in SF6 gas, it becomes a mixed gas boiling point, so liquefaction at a pressure lower than the critical pressure of SF6 gas. Liquefaction recovery was limited to SF6 gas recovery containing no impurities.
[0006]
However, generally, the SF6 gas sealed in the electric equipment rarely maintains the initial state, and impurities (mostly air) are mixed.
Conventionally, for the liquefaction and recovery of SF6 gas containing air, a rectification separation method such as cryogenic separation is employed.
[0007]
JP-T-2001-508390 discloses a gas stream containing a small amount of sulfur hexafluoride, an adsorbent capable of selectively absorbing sulfur hexafluoride, and a method for removing sulfur hexafluoride from the gas stream. A method for recovering sulfur hexafluoride is described which comprises contacting under conditions suitable for selective absorption.
[0008]
[Patent Document 1]
Table 2001-508390
[Patent Document 2]
JP-A-2001-038145
[Patent Document 3]
JP-A-2002-019900
[Patent Document 4]
JP-A-2000-088191
[0009]
[Problems to be solved by the invention]
Conventionally, gas recovery and liquefaction recovery at the site has generally been requested to a gas equipment manufacturer. However, at present, when SF6 gas is designated as a global warming gas, it is necessary to collect a small amount of gas, and a user of a gas-filled device may collect gas.
In such a situation, it is desired that the collection method on site can be simplified, but it becomes difficult for skilled workers to perform the collection work, and due to poor work procedures, air entrapment during collection frequently occurs and liquefaction It is expected that recovery will be more difficult.
[0010]
There are two methods for recovering SF6 gas: gaseous recovery and liquefaction recovery. However, considering the volumetric efficiency of transportation, it is desirable to recover liquefaction. That is, the volumetric efficiency becomes 1:12. However, in the case of liquefaction and recovery, if there is an impurity such as air in the gas, it becomes the mixed gas boiling point with the impurity, and if the amount of air mixed in is large, it is affected by the cryogenic boiling point on the air side, and is lower than the critical pressure of SF6 gas. Liquefaction at almost room temperature is not possible.
[0011]
Generally, SF6 gas sealed in an electric device is not an initial gas but contains impurities (mostly air). In addition, air is mixed in the process of recovering the gas. Conventional liquefaction and recovery of SF6 gas mixed with air is considered to be impossible only by a rectification separation method such as cryogenic separation, but in that case, the equipment is large-scale, and the cost and the size of the equipment are reduced. Cannot be used as a local gas recovery device.
From the above situation, there is a need for a system and method that can easily recover SF6 gas by a recovery method that can be transported to a final disposal facility in a liquefied state with high transport efficiency.
[0012]
In view of the above, the present invention provides a system and a method that can easily collect SF6 gas by employing a recovery unit and a method that can be transported to a final disposal facility in a liquefied state with high transport efficiency. Aim.
[0013]
By providing such a system and method, a cylinder or a gas bag recovery device with high transport efficiency which has been conventionally used for liquefaction recovery can be used even for the treatment of SF6 gas mixed with air.
Further, the present invention provides a low-cost recovery method to a customer by enabling transportation in a liquefied state with high transportation efficiency to a final disposal facility, and provides an information processing method for this purpose.
[0014]
[Means for Solving the Problems]
The present invention relates to a sulfur hexafluoride gas recovery method for liquefying sulfur hexafluoride gas and recovering it as liquefied sulfur hexafluoride, wherein the sulfur hexafluoride gas containing air is mixed with the sulfur hexafluoride gas. Provided is a sulfur hexafluoride gas recovery system and method for repeatedly liquefying part by part while separating part of the gas.
The present invention also provides an overall system for easily recovering sulfur hexafluoride gas by connecting and combining a circulation recovery system for recovering sulfur hexafluoride gas and a combus recovery system, and a method of using the same.
[0015]
The present invention also provides a method for recovering liquefied sulfur hexafluoride gas by liquefying sulfur hexafluoride gas, wherein the sulfur hexafluoride gas containing air is mixed with the sulfur hexafluoride gas. Provided is a sulfur hexafluoride gas recovery system and method for adjusting the pressure of a mixed gas in accordance with the amount of air to be separated and then liquefying partly while separating part of the air.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall system diagram showing an embodiment of the present invention. FIG. 2 is a detailed diagram of the system. This system consistently performs SF6 gas recovery processing in equipment installed at a customer site without releasing it to the atmosphere.
[0017]
FIG. 1 shows the concept of the present system. There are two SF6 gas recovery methods. One is a combus collection system 1, and the other is an on-site collection system 2.
In the combustor recovery system 1, SF6 gas is transferred from a recovery source provided on the utility pole 3, for example, a high-pressure AC gas load switch 4 to the gas bag 5 via the transfer device 17, and the general-purpose gas bag 5 is used. It is transported by the transport system 6 to the site where the SF6 liquefaction and recovery device 7 is provided, where it is liquefied, reduced in volume and stored in the cylinder 8 as described later. When a plurality of cylinders 8 are collected (bundle 9), they are transported to the recovered gas final disposal site 11 by the recovered gas filling cylinder transport system 10. In this way, the gas bag into which SF6 gas has been transferred from the SF6 gas recovery source is connected to the circulation recovery system 100 described below to form a combus recovery system, and new SF6 gas is injected into the circulation recovery system 100. You.
[0018]
In the on-site recovery system 2, the above-described dedicated SF 6 liquefaction and recovery device 7 and a cylinder 8 are set and disposed on the on-site recovery vehicle 12. The worker 13 connects the connection hose 16 to the collection target device 15 in the local factory 14, transfers the SF6 gas to the SF6 liquefaction and recovery device 7, immediately performs liquefaction work, and transfers the liquefied SF6 to the cylinder 8. First, the vehicle is transported by an on-site recovery vehicle 12, and transported to a recovered gas final disposal site 11 according to a recovered gas filling cylinder transport system 10.
[0019]
FIG. 2 shows the details of the SF6 liquefaction and recovery apparatus 7 and the recovery system and method. In FIG. 2, the system includes a diluted SF6 circulation type liquefaction / recovery device 21, a control system 22, and a liquefied SF6 gas recovery system 23 using a recovery container (bomb) 44.
The lean SF6 circulating liquefaction and recovery apparatus 21, the control system 22, and the liquefied SF6 collection system 23 can be mounted on a vehicle. Hereinafter, the three are collectively referred to as a diluted SF6 circulation type liquefaction apparatus 21 or the like.
[0020]
In FIG. 2, a recovery device inlet valve 31, a positive pressure recovery line automatic valve 32, a vacuum recovery automatic valve (1) 33 arranged in parallel with the positive pressure recovery line automatic valve 32, a vacuum recovery surge tank (1) 34, Vacuum recovery pump (scroll type) 35, vacuum recovery surge tank (2) 36, vacuum recovery line pressure adjusting automatic valve 37, vacuum recovery automatic valve (2) 38, positive pressure recovery line automatic valve 32, and vacuum recovery automatic valve (2) ), A recovery compressor 39, a filter (1) 40, a filter (2) 41, a liquefier 42, a recovery device outlet valve 43, a recovery container (cylinder) (corresponding to the above-described cylinder 8) 44, a liquid phase line The valve 45, the gas phase line valve 46, the pressure regulating valve 50, the membrane separation device 51, the adsorption tower 53, and the impurity gas return valve 59 are connected as shown in the figure, and a circulation recovery system (circulation system) 100 is formed.
[0021]
The circulation recovery system 100 has paths A, B, C, D, E, F, G, H, I, J, K, L, and N, as shown in FIG. The system M is provided with a valve 47 for analysis, and the oxygen concentration meter 52 is connected to the system M. As described above, the system path M is for measuring the state of the mixed gas flowing from the system path L but flowing through the system path, and may be considered to form a part of the circulation recovery system 100 described above. The oxygen concentration is determined by the oxygen concentration meter 52, and finally the amount of air mixed in is determined as data.
[0022]
An external device to be recovered or a gas bag recovery device 58 is connected to the circulation recovery system 100 as shown in the figure.
The paths G, H, and J are parallel to the paths BC, and the paths H and I constitute one small circulation system 101, and the target gas circulates as indicated by arrows.
[0023]
Next, the operation of the present system will be described.
The device to be recovered or the gas bag recovery device 58 is connected to the lean SF6 circulation type liquefaction recovery device 21, that is, the circulation system. The recovered gas is introduced into the system from the recovery device inlet valve 31.
[0024]
When the recovered gas is at a positive pressure, the recovered gas is introduced into the recovery compressor 39 from the line A → B → C → D, and is boosted by the recovery compressor 39.
When the pressure of the recovered gas becomes negative, the vacuum recovery pump 35 is started, and the pressure is increased by the recovery compressor 39 via the line A → G → H → J → D.
[0025]
The pressurized collected gas is removed of dust and water by the filters 40 and 41, and is introduced into the liquefier 42.
All of the recovered gas cooled by the liquefier 42 is liquefied at the liquefaction pressure peculiar to SF6 as long as there is no mixing of air. If air is mixed, SF6 gas is liquefied in a proportion determined by the concentration of air.
The recovered gas that has become a gas-liquid mixed phase is introduced into the recovery container (cylinder) 44 through the system path K.
[0026]
Since the SF6 gas liquefies only in a proportion (part) controlled by the concentration of air, the recovery gas introduced into the recovery container 44, which is a part of the recovery means, has two phases as shown in the figure. Split. That is, liquefied SF 654 is accumulated in the lower part of the cylinder, and SF 6 gas containing air is accumulated as a gas in the upper part. In this case, the recovered gas is introduced from a pipe 56 that penetrates through the recovery container 44 and opens at the lower part. By doing so, the recovered gas that flows in later flows into the liquefied SF 654 accumulated to be introduced from the lower side, and is further cooled by the accumulated SF 6 to be in a state where it is easily liquefied.
The concentration of air in the mixed gas stored in the upper portion becomes higher as the SF6 gas is liquefied.
The SF6 gas having an increased amount of air mixed therein as a gas is extracted from the system L, and the mixed gas is introduced into the oximeter 52 via the system M line to measure the oxygen concentration.
[0027]
The measured oxygen concentration signal is transmitted via a signal converter 48 to a control computer 49 constituting the control system 22. The control computer 49 calculates the mixed air concentration from the measured oxygen concentration, and calculates the required liquefaction pressure from a liquefaction pressure table which is previously obtained on a trial basis and compiled in a database. This required liquefaction pressure is not necessarily required to maintain the calculated boiling point. Since the boiling point and density of air and SF6 gas are significantly different, in this case, the recovered gas cannot be an ideal mixed gas. The pressure of the SF6 gas into which air is mixed is set to a value in a liquefaction pressure table which is prepared in a database in advance. In this case, even if the pressure is lower than the critical pressure of the theoretical mixed gas, a part of SF6 gas is liquefied. By controlling the pressure to the pressure, the power required for increasing the pressure can be reduced. If the power reduction is to be reduced, the pressure may be set to the critical pressure or the pressure or more. Even in this case, it is preferable to set the pressure at which a part of the SF6 gas in the mixed gas is liquefied.
In the above example, the case where the mixing ratio of air fluctuates has been described. As in the case of processing a specific SF6 gas, the mixing ratio of air is predicted in advance, and when the oxygen concentration meter 52 is not required, the pressure can be set in advance.
[0028]
The control computer outputs a signal to control the outlet pressure of the recovery compressor 39 to the calculated pressure by the processing device. The output signal is sent to the pressure control valve 50 via the control device 57, and the compressor outlet pressure is controlled based on the signal.
[0029]
The mixed gas at the outlet of the pressure control valve 50 returns to the inlet line of the recovery compressor 39 via the system N, and circulates again through the system to the recovery container 44 via the recovery compressor 39.
The system N is provided with a membrane separation device 51 having a membrane for separating SF6 gas and oxygen gas (air). Oxygen gas (air) in a possible amount, that is, a part of the amount, is removed by membrane separation, the mixed gas is circulated, and SF6 gas is repeatedly liquefied and collected one by one. In the present embodiment, the cost is reduced by adopting a method of removing a part of the impurities instead of removing the impurities collectively by the membrane separation device 51. When passing SF6 gas having an air mixing concentration of 10%, about 3% of air is removed by passing through the membrane separation device 51 once. As described above, in the present embodiment, the cooling and filling is performed by adopting the recovery container of membrane separation + circulation + two-phase storage, and SF6 gas is sequentially liquefied to measure the volume reduction.
[0030]
Recirculation recovery and volume reduction are continued until the gradually increasing pressure of the recovery compressor outlet line oxygen concentration reaches the oxygen concentration required experimentally. The limit value of the amount of air entrapment is obtained by performing a test in advance, and is taken into the control computer 49 as a database.
The recovered gas that could not be liquefied is compressed and filled into another cylinder.
[0031]
The liquefied SF6 is recovered from the liquefied SF6 gas recovery system 23. A mixed gas of air and unliquefied SF6 gas stays in the upper portion of the recovery container 44, and liquefied SF6 stays in the lower portion. The amount of the liquefied SF6 increases by the above-described circulating process. The introduction is stopped and another collection container is used for collection. The collection container storing the liquefied SF 6 is transported for destruction processing.
[0032]
In the collection container, SF6 gas containing a small amount of air is liquefied, and much air accumulates in the upper portion of the collection container 44 as a gas due to the density. By steadily extracting the gas portion by drawing it out, the concentration of SF6 in the recovery container becomes high, and the state becomes easy to liquefy.
[0033]
As described above, the liquefaction means for the sulfur hexafluoride gas, the liquefied liquefied sulfur hexafluoride recovery means, the air staying in the liquefied hexafluoride recovery means, and the discharge means for discharging the sulfur hexafluoride, Pressure adjusting means for controlling the pressure based on the data of the amount of air mixed measured by the measuring means for measuring the amount of air mixed in the mixed gas of sulfur fluoride gas and air; and the pressure control by circulating the mixed gas. Below, a circulation recovery system is formed from an air separation unit that separates part of the air, and a sulfur hexafluoride recovery system that repeatedly recovers a sulfur hexafluoride gas from the mixed gas is configured.
[0034]
Liquefied sulfur hexafluoride gas liquefaction means, liquefied liquefied sulfur hexafluoride recovery means, air staying in the liquefied sulfur hexafluoride recovery means, and discharge means for discharging sulfur hexafluoride gas; Pressure adjusting means for controlling the pressure based on the data of the amount of air mixed measured by the measuring means for measuring the amount of air mixed in the mixed gas of sulfur fluoride gas and air; and the pressure control by circulating the mixed gas. Below, a circulation recovery system is formed from air separation means for separating a part of air, and a gas bag into which sulfur hexafluoride gas has been transferred from a sulfur hexafluoride gas recovery source is provided to the circulation recovery system. A sulfur hexafluoride recovery system comprising a continuous combustor recovery system for continuously introducing new sulfur hexafluoride gas into the circulation recovery system is configured.
[0035]
Further, a liquefaction unit for SF6 gas, a liquefied liquefied SF6 recovery container, a discharge unit for discharging a mixed gas of air and SF6 gas stagnating in the upper part of the liquefied SF6 recovery container, and a discharge unit provided for the discharge unit Measuring means for measuring the amount of air mixed in, pressure adjusting means controlled based on the amount of air mixed measured by the measuring means, and membrane separation means for separating some air from the discharged mixed gas A circulating system is formed from the liquefied SF6 gas, a charging means for charging the air-mixed SF6 gas is connected to the circulating system, and a sulfur hexafluoride gas recovery system is configured to recover the liquefied SF6 from the liquefied SF6 recovery container.
[0036]
Further, a liquefaction unit for SF6, a liquefied and liquefied SF6 collection container, a discharge unit for discharging a mixed gas of air and SF6 gas staying in the upper portion of the liquefied SF6 collection container, and a part of air from the discharged mixed gas Forming a circulating system from the membrane separating means for separating methane, and connecting the feeding means for feeding the SF6 gas mixed with air to the circulating system, and recovering the liquefied SF6 from the liquefied SF6 recovery vessel. A gas recovery system is configured.
[0037]
A control computer provided with a database in which the relationship between the amount of air mixed in the mixed gas and the pressure controlled by the pressure adjusting means is stored in advance as data, and the air mixed amount signal transmitted from the measuring means A sulfur hexafluoride gas recovery system is configured to process and generate a control signal for controlling the pressure adjusting means based on the control signal.
[0038]
Next, a method of recovering SF6 gas in the diluted SF6 circulation type liquefaction and recovery apparatus 21 will be described separately for a case of large volume recovery and a case of small volume recovery.
○ In case of large volume collection
Depending on the capacity of SF6 gas filling equipment installed at each customer site,
Make a selection.
Carry the gas recovery equipment to the site and perform the recovery work. In some cases, diluted SF6
The circulation type liquefaction and recovery apparatus 21 and the like are carried into the site.
The pressure at the end of recovery minimizes the release of SF6 gas with a high global warming potential into the atmosphere.
In order to control, collection is performed up to 10 Torr.
In the case of gas recovery, the gas is filled in a recovery container (cylinder) 44 using the diluted SF6 circulation type liquefied recovery device 21 in order to take it back to the factory and carry it to the final disposal site.
You.
When the lean SF6 circulating liquefaction and recovery apparatus 21 and the like are brought to the site for on-site recovery, the recovery container (bomb) 44 is filled at the site.
When the filling operation of the collection container (cylinder) 44 is completed, the collection container (cylinder) 44 is carried into the final disposal site using the collection gas filling cylinder transport system 10 and is processed.
[0039]
○ In case of small volume collection
Use a combus collection device prepared in advance at the customer site to collect. Since simple recovery is sufficient, simple operation positive pressure recovery is self-pressure recovery, and it is possible to recover in a short time.
One example of a combus collection device is described in JP-A-2000-088191. In the SF6 recovery apparatus and method described here, a recovery gas bag formed with an elastic function is used. The collected gas bags are transported to a liquefaction filling factory using a general-purpose transport system such as a courier service (courier service, etc.). The transported gas bag is filled into a collection container (cylinder) 44 by the diluted SF6 circulation type liquefaction and recovery device 21 or the like in order to be carried into the final disposal site.
When the filling of the collection container (cylinder) 44 is completed, it is brought to the final disposal site for disposal.
The SF6 recovery using a combus recovery device and a gas bag has an advantage that the recovery time can be shortened because the recovery bag can be directly connected and press-fitted when the SF6 gas enclosed in the recovery target device is positive pressure, so that the recovery time can be shortened. Therefore, when it is important to shorten the collection time, even if the capacity of the collection gas is large, it is possible to cope by preparing a large number of the collection gas bags.
[0040]
Next, the gas bag centralized recovery device will be described.
FIG. 3 shows a centralized gas bag recovery device 61. The gas bag centralized recovery device 61 has a gas bag centralized recovery tank 62, a recovery tank evacuation device 63, a recovery tank exhaust valve 65 provided in a pipe 64 therebetween, and further provided in a plurality of device inlet valves 66 and a pipe 67. A recovery tank inlet valve 68 and an SF6 gas recovery target valve 70 provided on a pipe 69 connected to the above-described lean SF6 circulation type liquefaction recovery device 21 are provided.
[0041]
The plurality of conveyed gas bags 71 are connected to the apparatus inlet valve 66 via the recovered gas bag outlet valve 72.
The gas bag centralized recovery tank 62 is evacuated in advance by a recovery tank vacuum exhaust device 63 before connecting the gas bag, and maintains a vacuum state.
The valve operation is performed in the order of the recovery gas bag outlet valve 72, the device inlet valve 66, and the recovery tank inlet valve 68.
[0042]
Since the gas bag centralized collection tank 62 has a negative pressure by evacuation in advance, the SF6 gas in the gas bag is recovered to the negative pressure when the valve is opened, and the recovery is completed without releasing the SF6 gas to the atmosphere. can do.
[0043]
As described above, since SF6 gas is a gas having a high global warming potential (more than 20,000 times the global warming potential compared to carbon dioxide), its release into the atmosphere is regulated. For example, SF6 gas can be recovered by a simple system and method. In addition, even if a situation occurs in which air is mixed in at the time of a recovery operation or the like, transportation to the final disposal site can be carried out while improving efficiency. Further, the on-site collection work can be simplified and shortened, and a low-cost service for processing can be provided.
[0044]
A set pressure database is used for control pressure setting.
FIG. 4 is a control / operation block diagram for the control pressure calculation. Based on the waste gas amount 91 and the initial recovered gas oxygen concentration 102, as shown at 103, the waste gas amount (kg) and the waste gas amount (m³), Initial oxygen gas concentration (vol%), mixed air concentration (vol%), mixed air amount (m³), Theoretically recovered waste gas volume (m³), The theoretical recovered gas amount (kg) is determined as follows.
Waste gas amount: Wz kg
Waste gas volume: Vz m³
Initial oxygen gas concentration: X vol%
Contaminated air concentration: Y (vol%) = X / 0.21
Mixed air volume: Va (m³) = Vz * Y
Theoretical recovery waste gas volume: Vs (m³) = Vz−Va
Theoretical recovery gas amount: Ws (kg) = Vs * 146.05 / 22.41
The control pressure calculation / circulation number control 104 is performed using the recorded database.
[0045]
FIG. 5 shows a detailed diagram of the circulation number control 104. In FIG. 5, the control pressure is determined based on the data shown in the above figure corresponding to the oxygen concentration and SF6 concentration in the recovered gas which is a mixed gas of sulfur hexafluoride gas and air. In the figure, SF6 (100%), SF6 (99%) + Air (1%), SF6 (95%) + Air (5%), SF6 (90%) + Air (10%), SF6 (80%) + Air ( The control pressures (atm, abs) adopted corresponding to the temperatures in the case of 20%) and SF6 (70%) + Air (30%) are shown.
[0046]
The lower diagram in FIG. 5 shows the number of circulations and the air (O₂+ N₂), O₂, N₂And SF6 concentrations.
1) The liquefaction pressure is lower than the critical pressure. The calculation of the critical pressure as an ideal gas in the case of a mixed gas is described in literatures and the like.
2) When the present case is calculated, the mixed gas liquefaction pressure is obtained with respect to the temperature as shown in FIG.
3) However, actual experiments show that some liquids are liquefied even at a pressure lower than the calculated critical pressure. The pressure is determined experimentally and a database is created.
Control is performed according to the database.
4) The pressure in that case is lower than the calculated critical pressure. Therefore, controlling at that pressure reduces power.
[0047]
As described above, a database is created from the data shown in FIG. 5, and the number of circulations and / or the pressure employed during the separation of sulfur hexafluoride gas are set and the operation is performed using the database. Become.
[0048]
Actually, a collection and disposal report 106 is created using the collected gas (SF6) amount data 105 and various data 103, and a collection fee calculation 107 is performed.
In the collection and disposal report 106,
1) Theoretical recovery gas amount: Ws kg
2) Actual recovered gas amount: Wr @ kg
3) Actual released gas amount: w kg (Ws-Wr)
Is reported and output.
[0049]
For the collection fee calculation 107,
1) Collection cost: Cr ￥ / book
2) Disposal cost: Cs ￥ / book
3) Shipping fee: Cm / piece
4) Collection cost: Ck ￥ / m³
5) Air content 混入: Va m³
6) Recycling cost: A $ / Air $ m³
7) Collection fee: C = Ws / 50 * (Cr + Cs + Cm) + A * Va
Is required.
[0050]
Although the present embodiment employs membrane separation, a method of adsorbing and removing air with an adsorbent or the like can also be employed. Any method that removes air by membrane separation or other adsorption can be employed. That is, various means are employed as the air separation means, but membrane separation is desirable for repeatedly recovering the sulfur hexafluoride gas repeatedly by circulation.
[0051]
i) The gas depressurized by the pressure control valve flows into the separation membrane.
ii) By evacuating the space between the separation membrane and the separation membrane storage container, air (O₂+ N₂) Is exhausted.
iii) In the current membrane, the removal performance of oxygen gas and the removal performance of nitrogen gas are different, and the residual impurities from the impurities after one pass do not become air composition, but are circulated to the last.
By doing so, the SF6 concentration increases and liquefies.
[0052]
When the air concentration in the SF6 gas in the initial stage is 20%, as shown in FIG. 5, from the experimental data, the mixed air is removed by about nine circulations, and the remaining SF6 gas can be liquefied. In actual operation, all gases cannot be liquefied in nine circulations due to mixing of fluids, but the conditions for terminating the circulation can be set by measuring the oxygen concentration.
[0053]
Next, a low-cost service providing method for recovering SF6 gas will be described.
As described above, this system liquefies SF6 gas regardless of the volume of SF6 gas-filled equipment installed at the customer site and does not release SF6 gas containing air to the atmosphere. It is a system that recovers and maximizes transport efficiency. Therefore, the cost factor can be determined depending on the amount of the recovered liquefied SF6 and the amount of air mixed therein. That is, the smaller the amount of liquefied SF6, the lower the service charge for SF6 gas recovery can be made. Therefore, the relationship between the amount of the liquefied SF 6, the amount of mixed air, and the service fee can be obtained in advance as data on a trial basis and stored in the control computer 49 as a database. Of course, transportation costs can be taken in, but the factor is small.
[0054]
According to this method, in the sulfur hexafluoride gas recovery method of liquefying sulfur hexafluoride gas and recovering it as liquefied sulfur hexafluoride, the sulfur hexafluoride gas containing air is liquefied by sulfur hexafluoride gas. A step of repeatedly liquefying a part of the mixed gas of the gas and the mixed air, a step of measuring the mixed information about the amount of air in the mixed gas by the measuring means, and inputting the measured mixed information and mixing Based on the mixed information of the air in the mixed gas processed by the control computer that controls the pressure of the gas pressure adjusting means and the information on the amount of the liquefied and liquefied sulfur hexafluoride, based on the mixed amount of the air, And the amount of liquefied sulfur hexafluoride and the treatment price as a database, the price for liquefaction of sulfur hexafluoride gas is input. Sulfur hexafluoride collecting method characterized by a step of computing the contaminating information liquefied sulfur hexafluoride amount information of the air in the mixed gas so that there is provided.
[0055]
FIG. 6 shows a method of the above-mentioned collection and disposal report 106 and collection fee calculation 107 by the control computer 200.
In these processes, a recovered gas amount calculation loop 108 and a liquefaction pressure control calculation loop 109 are used.
In the collected gas amount calculation loop 108, the contents of the customer order form 1) 1) shipping source, 2) waste gas amount, and 3) original use are input. This instructs a calculation process for obtaining the SF6 recovery amount 112.
The SF6 collection operation is started using the system described above (SF6 collection operation start 113). An SF6 purity initial measurement 114 is performed, and measurement data 115 is obtained.
[0056]
SF6 recovered gas amount calculation processing 116 is performed for the following contents.
Waste gas amount: Wz kg
Waste gas volume: Vz m³
Measured oxygen concentration: X vol%
Contaminated air concentration: Y (vol%) = X / 21%
Mixed air volume: Va (m³) = Vz * Y
Theoretical recovery SF6 amount: Vs (m³) = Vz−Va
Theoretical recovery SF6 amount: Ws (kg) = Vs * Ms / 22.41
The theoretical recovery gas amount 117 (Wskg) (that is, the theoretical recovery SF6 amount) is output, and the SF6 actual recovery gas amount 118 (Wrkg) is output. These are shown and displayed on the collection and disposal report 106.
A recovery charge calculation 107 is made from the theoretical recovered gas amount 117, and is shown and output. The contents of the collection fee calculation 107 are as shown in the figure.
[0057]
The service provision method and fee calculation method are as follows.
Using the recovered gas amount calculation loop,
[1] Input the volume of waste gas.
[2] (1) Measure the initial oxygen gas concentration of the waste gas.
[3] Perform the following calculation inside.
[0058]
Total amount of waste gas: Vz m³ (Input value)
Initial oxygen gas concentration: Xo%
Contaminated air concentration: Y (vol%) = Xo / 0.21
Mixed air volume: Va (m³) = Vz * Y
Theoretical recovery gas amount: Vs (m³) = Vz−Va
Theoretical recovery gas amount: Ws (kg) = Vs * 146.05 / 22.41
And calculate the fee as follows.
[0059]

The total recovery fee is based on the theoretical amount of recovered gas and the cost of discharging mixed air.
[0060]
Next, liquefier liquefaction temperature data 121 for the liquefaction pressure control calculation loop 109 is obtained and stored as temperature measurement data. These data, together with the result 123 of the SF6 purity initial measurement 114, are used in the SF6 liquefaction pressure determination process. Based on these data, a pressure control signal 125 is output with reference to the control pressure calculation / circulation number control 104 shown in FIG.
[0061]
【The invention's effect】
According to the present invention, regardless of the volume of the SF6 gas-filled device installed at the customer site, even if impurities such as air are mixed in the SF6 gas, air mixed in the SF6 gas is used. Since the SF6 gas is repeatedly liquefied part by part while separating a part of the gas, a system and a method for maximizing the transport efficiency can be provided. Further, according to this system and method, it is possible to perform processing of SF6 / 89 gas mixed with air at low cost, and accordingly, it is possible to provide a low-cost SF6 gas recovery method as a service.
[Brief description of the drawings]
FIG. 1 is an overall schematic system diagram of an embodiment of the present invention.
FIG. 2 is a detailed system diagram of an embodiment of the present invention.
FIG. 3 is a configuration diagram of a gas bag centralized recovery device.
FIG. 4 is a control / operation block diagram for control pressure calculation.
FIG. 5 is a control pressure calculation / circulation number control diagram.
FIG. 6 is a view showing processing contents of a control computer.
[Explanation of symbols]
Reference numeral 21: diluted SF6 circulating liquefaction and recovery device, 22: control system, 23: liquefied SF6 gas recovery system, 31: recovery device inlet valve, 32: automatic pressure suppression recovery line valve, 33: automatic vacuum recovery valve (1), 34 ... Vacuum recovery surge tank (1), 35 ... Vacuum recovery pump, 36 ... Vacuum recovery surge tank (2), 37 ... Vacuum recovery line pressure control automatic valve, 38 ... Vacuum recovery automatic valve (2), 39 ... Recovery compressor, 42: liquefier, 44: recovery container (cylinder) (corresponding to cylinder 8), 45: liquid phase line valve, 46: gas phase line valve, 47: analysis valve, 49: control computer, 50: pressure regulating valve, 51: membrane separation device, 52: oxygen concentration meter, 54: liquefied SF6, 55: mixed gas of air and SF6 gas, 58: equipment to be recovered or gas bag recovery device, 100: circulation recovery system (circulation system)

Claims (10)

In a sulfur hexafluoride recovery system that liquefies sulfur hexafluoride gas and recovers it as liquefied sulfur hexafluoride,
Liquefied sulfur hexafluoride gas liquefaction means, liquefied liquefied sulfur hexafluoride recovery means, air staying in the liquefied hexafluoride recovery means and discharge means for discharging sulfur hexafluoride, sulfur hexafluoride gas Pressure adjusting means for controlling the pressure based on the mixed data of air measured by the measuring means for measuring the mixed amount of air in the mixed gas of air and, under the pressure control by circulating the mixed gas, An apparatus for recovering sulfur hexafluoride, wherein a circulation recovery system is formed from an air separation means for separating a part of air, and sulfur hexafluoride gas is repeatedly recovered from a mixed gas. In a sulfur hexafluoride recovery system that liquefies sulfur hexafluoride gas and recovers it as liquefied sulfur hexafluoride,
Liquefied sulfur hexafluoride gas liquefaction means, liquefied liquefied sulfur hexafluoride recovery means, air staying in the liquefied sulfur hexafluoride recovery means, and discharge means for discharging sulfur hexafluoride gas; Pressure adjusting means for performing pressure control based on air mixing amount data measured by measuring means for measuring the mixing amount of air in the mixed gas of sulfur gas and air; and A gas bag into which a circulation recovery system is formed from air separation means for separating a part of air, and a sulfur hexafluoride gas is transferred from a sulfur hexafluoride gas recovery source is connected to the circulation recovery system. A recovery system for introducing a new sulfur hexafluoride gas into the circulation recovery system. In a sulfur hexafluoride recovery system that liquefies sulfur hexafluoride gas and recovers it as liquefied sulfur hexafluoride,
Liquefied sulfur hexafluoride gas liquefaction means, liquefied liquefied sulfur hexafluoride recovery means, air staying in the liquefied sulfur hexafluoride recovery means, and discharge means for discharging sulfur hexafluoride gas, Pressure adjusting means for controlling the pressure based on the air mixing data measured by the measuring means for measuring the mixed air quantity, and a part of the air is repeatedly separated from the mixed gas of sulfur hexafluoride gas and air A circulation recovery system is formed from the air separation means to be connected to the liquefied sulfur hexafluoride recovery vessel. A sulfur hexafluoride gas recovery device for recovering sulfur fluoride. In a sulfur hexafluoride gas recovery system that liquefies sulfur hexafluoride gas and recovers it as liquefied sulfur hexafluoride,
Liquefied sulfur hexafluoride gas liquefaction means, liquefied liquefied sulfur hexafluoride recovery means, discharge means for discharging a mixed gas of air and sulfur hexafluoride gas retained in the liquefied sulfur hexafluoride recovery means, discharge And a membrane separation means for separating a part of the air from the mixed gas, forming a circulation recovery system, and connecting the charging means for newly introducing the sulfur hexafluoride gas mixed with air to the circulation recovery system, and A sulfur hexafluoride gas recovery device for recovering sulfur hexafluoride from the liquefied sulfur hexafluoride recovery container. 5. The liquefaction unit according to claim 1, wherein the liquefaction unit includes a recovery compressor and a liquefier, and a recovery target device or a gas bag recovery device is connected to the circulation system. A sulfur hexafluoride gas recovery device, wherein the pressure is set to be higher than the internal pressure on the inflow side of the recovery compressor. The gas bag collecting device according to claim 5, wherein the gas bag collecting device includes a gas bag centralized collecting tank, and a plurality of collected gas bags connected to the gas bag centralized collecting tank and collecting sulfur hexafluoride gas. Sulfur hexafluoride gas recovery device. 5. The control unit according to claim 1, further comprising: a control computer including a database in which a relationship between an amount of air mixed in the mixed gas and a pressure controlled by the pressure adjusting unit is stored in advance as data. And processing and generating a control signal for controlling the pressure adjusting means based on an air mixing amount signal transmitted from the apparatus. In a sulfur hexafluoride gas recovery method of liquefying sulfur hexafluoride gas and recovering it as liquefied sulfur hexafluoride,
A method of repeatedly liquefying a sulfur hexafluoride gas partly while separating a part of the air mixed with the sulfur hexafluoride gas into air while separating part of the air mixed with the sulfur hexafluoride gas. Sulfur gas recovery method. In a sulfur hexafluoride gas recovery method of liquefying sulfur hexafluoride gas and recovering it as liquefied sulfur hexafluoride,
Repeat the sulfur hexafluoride gas mixed with air while adjusting the liquefaction pressure of the mixed gas of sulfur hexafluoride gas and air in accordance with the amount of air mixed, while separating a part of the air by air. A method for recovering sulfur hexafluoride gas, comprising liquefying a portion of the sulfur fluoride gas. In a sulfur hexafluoride gas recovery method of liquefying sulfur hexafluoride gas and recovering it as liquefied sulfur hexafluoride,
A step of repeatedly liquefying the sulfur hexafluoride gas to be mixed with air from a mixed gas of the sulfur hexafluoride gas and the mixed air by liquefaction means,
A step of measuring mixed information about the amount of air in the mixed gas by the measuring means, and inputting the measured mixed information, and controlling the pressure of the pressure adjusting means for the mixed gas by the control computer. Based on the information of air entrainment in the mixed gas to be treated and the information on the amount of liquefied sulfur hexafluoride to be liquefied and recovered, based on the previously recorded air entrainment amount and the amount of liquefied sulfur hexafluoride liquefied And having the treatment price as a database, performing a calculation process from the information on the amount of air mixed in the mixed gas and the information on the amount of sulfur hexafluoride that is liquefied with the price for the liquefaction of the sulfur hexafluoride gas, and Performing a sulfur hexafluoride gas recovery method.

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