GAS SUPPLYSYSTEM

The present invention relates to a gas supply system, for example, to a gas supply system used for gas supply devices supplying particular gases as various gases and liquefied gases or liquids filled in high pressure containers.

Background

Conventionally, many high pressure containers filled with various gases and liquefied gases or liquids (in case containers are filled with liquid or gas-liquid mixtures supplied in gaseous state, the generic name "liquefied gas" is used hereafter) are used in various manufacturing processes starting with semiconductor manufacturing processes; these liquefied gases are filled into semiconductor manufacturing devices which are consumption facilities for liquefied gas and various process devices (referred to hereinafter as "process devices") in gaseous or liquefied state. At this point, the container filled with liquefied gas is stored in the supply facility, sent to the process device via the supply pipe, and replaced when a residual amount below the set amount has been reached through consumption. Alternatively, there are cases when part of the piping unit connected to the filled container is opened during the inspection of the gas supply flow path. Here, the liquefied gas used in semiconductor manufacturing devices is often highly toxic and corrosive, and it is necessary to prevent leaking during operation as well as to prevent gas emission towards the exterior in case the gas is transferred into the prepared filled containers. Moreover, it is necessary to block the contact between special material gases such as SiH4 and open air, because said gases react with components such as

moist content in the air, degenerating and solidifying. Consequently, the special material gases in the pipes between the container valve and the on-off valves located on the upstream side of the decompression valve have to be purged using, for example, nitrogen, and then the pipes have to be purged again using special material gases from the container after a new filled container had been installed. The purged special material gas is subjected to detoxification in the exhaust gas treatment device during the subsequent process. In order to prevent such emissions, a method of purging residual gas in the pipes from the filled containers and a method of purging residual gas in the pipes of the entire supply system have been devised.

In concrete terms, as shown in Figure 6, a method of purging residual gas in the primary side pipe with high efficiency and of stopping the vacuum generator during pressurization inside the primary side pipe in a pressurization purge and the immediately previous purge has been proposed. Cylinder 101 storing gas

122 is provided with a cylinder main valve 123 and connected to a supply side via a charging pipe 102, a primary side pipe 114, an air operation valve 106, a pressure reducing valve 107, a secondary side pipe 119 and an air operation valve 110. An inert gas 115 flows into the primary side pipe 114 via the air operated valve 103. The primary side pipe is connected to the vacuum generator 111 via an air operated valve 105 and a pipe 120. The residual gas inside the primary side pipe is purged as exhaust gas 118 by automatically carrying out purging by applying pressure in which applying pressure for 2-10 minutes using inert gas and evacuation for 120 seconds are repeated. Here, 104 and 108 refer to pressure gauges, 109,110, and 112 refer to air operation

valves, 113 refers to a mass flow meter, 116 refers to a supply side, 117 refers to an inert gas such as nitrogen, and 118 refers to exhaust gas (see for example Japanese Unexamined Patent No. 2003-14193).

Problems to be Solved by the Invention

However, the problems described hereinafter have occurred in relation to the above-described liquefied gas supply device.

(i) In a method of purging residual gas as the one described above, upon the replacement of the cylinder 101, it is necessary to purge the entire interior of the primary side pipe 114 from cylinder main valve 123 to air operation valve 110 and pipe 120, and to replace it by gas 122 stored in the new cylinder 101; the volume that should be replaced inside the pipe may increase during the manufacturing processes that are often restrained in relation to the position of the filled container and pipes; valuable liquefied gas was lost to the manufacturing process as it was evacuated.

(ii) Moreover, the internal capacity of pipe that should be purged can be reduced by placing air operation valves 106 and 110 in the vicinity of the container valve if possible; on the other hand, upon purging the pipes by means of liquefied gas after the new filled container had been installed, it is necessary to purge by means of the charge pressure of the filled container; therefore, the amount of liquefied gas used for purging by means of evacuated liquefied gas having particularly high charge pressure is significant, (iii) In addition, the liquefied gas used in semiconductor manufacturing processes is often highly toxic and corrosive or reactive, the exhaust gas processing is indispensable, and there are many cases when special exhaust

gas processing is necessary. Consequently, in order to reduce the work load of the subsequent process of the exhaust gas processing device, further reduction of the purged special material gas amount was demanded.

The object of the present invention is to provide a gas supply system that can reduce the capacity of the pipe necessitating purging for the purification accompanying the installation/removal processes upon replacement of the filled container and inspection of the piping unit (referred to hereinafter as "container replacement and other processes"), minimize the feed gas amount evacuated through purging, and at the same time maintain stability by swift processing of the feed gas - filled container by means of a simple structure.

Means for Solving the Problem

In view of the above-described problems, the present inventors conducted intensive research and discovered that the aim can be reached by means of the gas supply system described below. The invention is based on this discovery.

The present invention comprises a feed gas - filled container provided with a container valve, a mounting unit on which the filled container is mounted, a gas consumption facility for consuming the gas, a piping unit connecting the filled container to the gas consumption facility, a pressure regulation unit located on the piping unit, and a process control unit controlling the activity of each part, characterized in that pipe Lo having at both ends on-off valve Va, located in the proximity of the container valve, and on-off valve Vb, located in the vicinity of the primary side of the pressure regulation unit is provided as unit of the piping unit,

and at the same time characterized in that the decompression process unit and the inert gas supply unit are connected via on-off valve Vc to pipe La connecting the container valve and the on-off valve Va.

As explained above, purging using the feed gas filled into the filled container is indispensable for the purging process necessary in such processes as the semiconductor manufacturing process, and problems have occurred in reducing the processing amount thereof. Particularly, the piping unit after the pressure regulation unit is set for each manufacturing process in many cases, and the purging method and the method of processing the gas filled container can be restricted. The present invention is such that it should reduce the yield of feed gas necessary for the purge of the flow path as much as possible; pipe Lo having a set capacity and on-off valves at both ends is located between the container valve and the pressure regulation unit, the capacity of pipe La connecting the container valve and pipe Lo is minimized, and the purging processing amount of the feed gas can be reduced to a great extent by purging pipe La using the feed gas having a set pressure preserved inside pipe Lo. Consequently, it has become possible to provide a gas supply system that can reduce the internal capacity of the pipe necessitating purging for the purification accompanying the installation/removal processes upon replacement of the filled container, minimize the feed gas amount evacuated through purging, and at the same time maintain stability by swift processing of the feed gas - filled container by means of a simple structure.

Moreover, pipe Lo can form an independent space due to the valves located on both its ends. Namely, a buffer space can be formed connecting the flow path after the large variation factor gas filled container and the flow path before and after the pressure regulation unit necessitating stability; by using these on-off valves, such a buffering feature can be used efficiently, and a filled container having high processability can be safely operated.

The phrase "gas supply system" refers to a system for supplying feed gas from the filled container to the gas consumption facility by means of the flow path after the container valve and the associated components and operation part, and it includes the supply of substances forming gaseous matter, liquid matter, or mixtures from the filled container in gaseous state to the gas consumption facility. Moreover, the "purging process" is not only a process carried out for purification in the container exchange, but it refers to all processes carried out for the inventive gas supply system in order to make the supply of gas to the gas consumption facility actually possible. "Piping unit" includes pipe Lo, the pipes to the gas consumption facility comprising pipes La-Ld, and the on-off valves and pressure gauge located on said pipes.

The present invention is the above-described gas supply system characterized in that the flow path is purged by means of:

(1 ) as the process of removing the piping unit from the filled container, at least a process of operating the decompression process unit and evacuating the gas inside pipe La, and a process of operating the inert gas supply unit and filling pipe La with inert gas are

carried out; these processes are repeated for a predetermined number of times Mo; (2) as the process of installing the piping unit on the filled container, at least a process of operating the decompression process unit and evacuating the gas inside pipe La, a process of opening the oη-off valve Va and filling pipe La with the feed gas preserved inside pipe Lo are carried out; these processes are repeated for a predetermined number of times Na.

As described above, pipe Lo having the predetermined volumetric capacity is located between the container valve and the pressure regulation unit; the internal capacity of pipe La necessitating purging is minimized, and the purging processing capacity of the feed gas can be greatly reduced by carrying out the purging of pipe La using the feed gas inside pipe Lo. In addition to the originality of such a flow path structure, by combining (1 ) the primary process of repeating purging by means of "decompression-inert gas" in the process of removing the filled container and (2) the secondary process of repeating purging by means of "decompression-feed gas" in the process of installing the filled container, the inventive gas supply system prevents contamination upon opening, and the processing capacity of the evacuated feed gas can be further reduced, ensuring purging.

The present invention is the above-described gas supply system characterized in that the residual pressure of the filled container before the purging process is Po, the set pressure of the pressure regulation unit is Ps, the capacity of pipe Lo

comprising the on-off valves Va and Vb is Go, the capacity of pipe La comprising the on-off valve Vc is Ga, and the higher limit of the number of repetitions Na is determined by means of Equation 1 :

Na < log (Po/Ps) / (Go + Ga) ... (Equation 1 )

The effects of the purge can be increased by repeating the purge by means of "decompression-gas" several times; on the other hand, the reduction of the processing amount of the evacuated feed gas has been demanded in the secondary process by means of "decompression-feed gas". Additionally, pipe

Lo located between the container valve and the pressure regulation unit performs the above-described important function and at the same time its internal capacity plays an important role in the relation with pipe La necessitating purging. Namely, for continuing the supply of gas under stable conditions in gas supply after the purging process, the set value of the charge pressure, namely, the set pressure of the pressure regulation unit is preferably maintained; the present invention has clarified the adequate standard criteria of the number of repetitions Na of the secondary purging process necessary for preserving these conditions, from the relation of pipe Lo and the capacity inside pipe La.

The present invention is the above-described gas supply system characterized in that on-off valve Vd is located on the secondary side of the pressure regulation unit, and the decompression process unit and the inert gas supply unit are connected via on-off valve Ve to pipe Ld connecting on-off valve Vd and the

pressure regulation unit or/and to pipe Lb connecting the pressure regulation unit and on-off valve Vb.

The least extensive pipe necessitating purging in the gas purging system corresponding only to the replacement of the filled container is only the unit connecting the filled container and the piping unit; however, in the actual production process, there are many modifications in the inspection of the piping unit or the concentration of the liquefied gas supplied and the types of gas. Moreover, manufacturing processes extremely reluctant to the presence of fine impurities such as semiconductor manufacturing processes often need maintenance work corresponding to the purging of the flow path comprising the pressure regulation unit, as shown in Figure 6. Namely, it is necessary to carry out gas isolation of the flow path comprising unit of the secondary side of the pressure regulation unit from the container valve with the piping system until the gas consumption facility. The present invention carries out gas isolation of the piping system until the gas consumption facility after locating the on-off valve Vd on the secondary side of the pressure regulation unit, and makes purging of both flow paths possible simultaneously or alternately by forming a system connecting the decompression unit and the inert gas supply on the flow side on the upstream and downstream of pipe Lo, locating pipe Lo between the piping unit from the container valve to the pressure regulation unit. A gas supply system that can minimize the processing amount of the feed gas evacuated through purging and that can maintain stable and swift processing of the filled container containing such gases as liquefied gas by means of operable and simple structure has thus become possible.

The present invention is the above-described gas supply system characterized in that the flow path is purged by means of:

(1 ) as the process of removing the piping unit from the filled container, at least a process of operating the decompression process unit and evacuating the gas inside pipe La or pipe La, pipe Ld and pipe Lb, as well as a process of discharging via pipe La and a process of operating the inert gas supply unit and filling pipe La with inert gas are carried out; these processes are repeated for a predetermined number of times Mo; (2) as the process of installing the piping unit on the filled container, at least a process of operating the decompression process unit and evacuating the gas inside pipe La, pipe Ld and pipe Lb, and a process of opening on-off valve Va or/and on-off valve Vb and filling pipe La, pipe Ld and pipe Lb with the feed gas preserved inside pipe Lo are carried out; these processes are repeated simultaneously or alternately for pipe La and pipe Ld or/and pipe Lb for a predetermined number of times Nb.

The purging process of the gas supply system having such a gas isolation function is preferably carried out not only on the upstream side of pipe Lo but also on the downstream side of said pipe. In addition to combining the primary process by means of inert gas in the purging of pipe La and the secondary system by means of feed gas, the inventive gas supply system makes it possible to further reduce the processing capacity of the evacuated feed gas by carrying out the decompression process in the gas isolation process of pipe Ld or/and

pipe Lb located on the downstream side of pipe Lo and the purging process by means of "decompression-feed gas" simultaneously or alternately on the upstream and downstream of pipe Lo, and at the same time it makes it possible to ensure the purging process.

The present invention is the above-described gas supply system characterized in that the capacity of the pipe Ld and the pipe Lb comprising the on-off valves Vd and Ve is Gb, and the number or repetitions Nb is determined by means of the Equation 2 or Equation 3:

Nb < log (Po/Ps) / (Go + Ga + Gb) ... (Equation 2) Nb < log (Po/Ps) / (Go + Ga + n x Gb) ... (Equation 3) Here, a is the ration in case the number of purges of pipe Ld and pipe Lb is lower than the number of purges of pipe La, and the former was set to 1.

The addition of the purging process of the downstream side of pipe Lo influences the number of repetitions of the purging process because the volume of feed gas preserved in pipe Lo is limited. The inventive gas supply system has clarified the adequate standard criteria of the number of repetitions Nb of the secondary purging process necessary for preserving these conditions, from the total internal capacity of pipe Lo, pipe La, pipe Ld and pipe Lb. At this point, the number of purges of pipe Ld and pipe Lb can be made smaller than the number of purges of pipe La because the flow path is practically not polluted and attention is given to gas isolation, and the processing amount of feed gas evacuated through purging can be further decreased.

The present invention is the above-described gas supply system characterized in that after the aforementioned processes (1 ) and (2), as (3) the process of supplying gas to the consumption facility, at least while the on-off valves Va-Ve are closed, after opening the container valve, the on-off valves Va and Vb or the on-off valves Va, Vb and Vd are opened in order at predetermined time intervals, and feed gas is fed from the filled container to the gas consumption facility via the piping unit.

As shown above, after processes such as container replacement and other processes, the pressure inside the pipes from the container valve to the pressure regulation unit is lower even than the internal pressure of the filled container, and the difference can be very big particularly with high pressure gases that do not form a liquid phase inside the filled container. When the container valve is opened under such circumstances and high pressure is suddenly applied to the pressure regulation unit, the controlled pressure thereof can be influenced. The inventive gas supply system efficiently uses the pipe Lo installed until the pressure regulation unit and the valves Va and Vb; by opening on-off valves Va and Vb or valves Va, Vb and Vd in order at predetermined time intervals, the application of such high pressure can be moderated. Moreover, as the capacity of pipe Lo is larger than that of pipe La or pipe Ld and Lb, pipe Lo forms a buffer in the flow path until the pressure regulation unit, and preserving high stability of the control pressure of the pressure regulation unit becomes possible by operating the valves.

Effects of the Invention

By virtue of the present invention it is possible to obtain a gas supply system that can reduce the capacity of the pipe necessitating purging for the purification upon replacement of the filled container and inspection of the piping unit, minimize the evacuated feed gas amount necessitating purging by efficiently using feed gas trapped inside, and at the same time maintain stability by swift processing of the liquefied gas filled container by means of simple structure.

Preferred Embodiment of the Invention Hereafter, the embodiments of the present invention will be described on the basis of the drawings. The basic embodiment is a gas supply system comprising a feed gas-filled container provided with a container valve, a mounting unit on which the filled container is mounted, a gas consumption facility for consuming the gas, a piping unit connecting the filled container to the gas consumption facility, a pressure regulation unit located on the piping unit, and a process control unit controlling the activity of each unit, wherein pipe Lo, having on-off valve Va, located in the proximity of the container valve and on-off valve Vb, located in the vicinity of the primary side of the pressure regulation unit at both ends, is provided as unit of the piping unit, and at the same time the decompression process unit and the inert gas supply unit are connected via on- off valve Vc to pipe La connecting the container valve and on-off valve Va.

Basic configuration example of the inventive gas supply system

Figure 1 is a schematic illustration of the basic configuration example of the inventive gas supply system (referred to hereinafter as "the inventive system A").

The inventive system A assumes the case when filled container 1 filled with special gas (feed gas) is mounted as it was preserved by means of mounting 2, and the filled container is replaced the moment the feed gas in the filled container 1 becomes lower than the predetermined amount. Here, the case when the feed gas is liquefied gas is explained. The filled container 1 delivers liquefied gas from the container valve located on the upper unit of said filled container 1. Pipe La is connected to container valve 1a, and to process device 4 which is the consumption facility by means of pipe Lb, pipe Ld, pipe Ld and the piping unit formed of pipe Lp connected to pipe Ld. The charge pressure of the liquefied gas evacuated from the filled container is adjusted by means of the decompression valve 3 (corresponding to the "pressure regulation unit") located on pipe Lb and said liquefied gas is fed to the process device 4 (corresponding to the "gas consumption facility"). Supply is set ON/OFF by controlling the on-off valve Vd. Moreover, the purging process which is one of the particularities of the inventive system A is operated by means of the purging process unit 5 connected with pipe La via pipe Lc and on-off valve Vc. Such a gas supply function and purging process function are controlled by means of the process control unit 6.

Purging at least pipe La connected to container valve 1 is preferred as the purging process during the removal or installation of the piping unit upon replacing the container. Moreover, same applies to usage re-initiation after long- term non-usage. This is in order to prevent contamination of the environment due to vaporization of the liquefied gas or contamination of the flow path due to reaction with oxygen and moist components in the air, or dust particles in the air.

Here, feed gas is preferably used as the purge gas; however, there are many cases when the scarcity of this feed gas makes it expensive and cases when the gas is corrosive, toxic, or dangerous; carrying out a secondary purging by means of a small amount of feed gas is preferred before the actual supplying process, after the primary purging had been carried out using such substances as nitrogen and purified air, or inert gas. The inventive system A is an invention that should reduce the amount of purged gas of the feed gas as much as possible during this secondary purging; the pipe Lo having a predetermined capacity has valves Va and Vb at both ends and is located between the container valve 1a and the decompression valve 3; the purging processing amount of the feed gas can be reduced to a great extent by setting the capacity of pipe La connecting the container valve 1a and the pipe Lo to a small amount and purging pipe La using feed gas having a predetermined pressure kept inside pipe Lo.

Here, the feed gas constituting the object of the inventive system A is applicable to a system for supplying from the filled container 1 to the process device 4, as explained above; this feed gas comprises inside filled container 1 various gases and liquefied gases, liquids or mixtures thereof. In concrete terms, gases that can be used include compressed gases such as oxygen, hydrogen, or argon; special material gases (liquefied gases having low vapor pressure represented by NH3, BCL.3, CL.2, SiH2CL2, Si2Hδ, HF, C3F8, WFδ) used in the semiconductor manufacturing process; liquefied gases such as carbon dioxide, or water for hydrogenation and various refrigeration media. Liquefied gas delivered in liquid state until before the process device 4 and fed in gaseous state using a

vaporizer is included. The inventive system A is useful because it is necessary to purge the container valve and the connection pipe (corresponding to pipe La) upon replacement of the filled container 1.

There are no particular restrictions with regard to the container regularly filled with feed gas from the exterior or with regard to the pressure container carried for each container of the filled container 1 , as long as it necessitates the purging process of the piping unit upon replacing the container. Moreover, the method of management of the filled container comprising the necessity of processing upon replacing the container has no particular restriction when used for the inventive system A; however, selection is made according to the characteristics of the filled feed gas and supply conditions or to the conditions of usage of the process device. For example, the method of grasping the consumption amount by observing the charge pressure, the total amount comprising filled container 1 , and the supply flow or, for liquefied gas, the method of installing a level sensor inside filled container 1 and managing the liquid amount is used. Moreover, for liquefied gas, in order to preserve a stable supply amount, a method of observing not only the charge pressure, but also preferably keeping the liquid phase humidity constant, observing liquid phase humidity, and warming the filled container 1 is used.

As shown in Figure 1 , the piping unit consists of pipe La, pipe Lo, pipe Lb, pipe Ld, and pipe Lp connected to pipe Ld, and at the same time it contains the necessary on-off valves and pressure gauges for forming the structure/functions of the inventive system A. In concrete terms, pressure gauge Sa surveying the

charge pressure to the process device 4 is located on pipe La. The on-off valves Va and Vb performing the connection to pipe La and pipe Lb and the opening/closing function of the flow path are located on pipe Lo connected to said pressure gauge Sa. In addition, pipe Lb is connected to decompression valve 3, and on-off valve Vd performing the connection to pressure gauge Sb surveying the charge pressure to the process device 4 and pipe Lp and the opening/closing function of the flow path are located on pipe Ld connected via decompression valve 3. Moreover, in order to prevent condensation of the feed gas when temperatures drop on the flow path during winter, a temperature sensor measuring the pipe temperature and the environment temperature, a heater for heating the pipes, a throttle for adjusting supply flow amount and a flow amount regulation unit are located on the actual device (none is shown in the figures).

The purging process unit 5 performs the decompression function of the piping unit necessary in the purging process of the inventive system A and the inert gas supply function; it consists of the decompression process unit comprising on-off valve Vf, pipe Lf, and gas ejector Fv, and of the inert gas supply unit comprising on-off valve Vg and pipe Lg; in addition, pressure gauge Sc is installed in order to confirm each function. The case of the decompression process unit using the gas ejector Fv is shown in Figure 1. By using inert gas such as nitrogen as the gas introduced into the venturi tube, the purged feed gas can be evacuated outside the inventive system A in unreacted state, and the recovery or removal process can be easily carried out. Moreover, common nitrogen is often used as the inert gas supplied from the inert gas supply unit because it has almost no

reactivity and it can be easily procured. However, the present invention is not limited to the use of the gas ejector Fv; a vacuum pump or a vacuum compressor can also be used. Moreover, the purging process can also be controlled manually or automatically by means of process control unit 6.

Supply method using the inventive system A

The gas supply system using the inventive system A has a function that makes it possible to supply the feed gas from the filled container using the purging process as the first step, and a function for actually supplying gas to the process device by means of the gas supply process as step 2. Moreover, the purging process in the inventive system A consists of (1 ) a process of removing the filled container (including gas isolation) and (2) a process of installing the new filled container. The case when replacing the filled container 1 has become necessary due to a reduction of the feed gas in the filled container 1 in actual operation conditions is explained hereafter in general terms.

(1 ) Process of removing the filled container using the inventive system A The process of removing the filled container, at the time of container replacement, can be carried out following the steps below, using the inventive system A shown in Figure 1.

(1 -1 ) Close container valve 1a and on-off valves Va-Vg. (1-2) Open on-off valve Vc and perform the decompression process of the purging process unit 5, and evacuate the gas inside pipe La. In concrete terms, open on-off valve Vf, and by activating gas ejector Fv, pipes Lf and Lc are decompressed via pipe La, and

the gas containing the feed gas inside can be evacuated. The state of stability can be verified using pressure gauges Sa and Sc. Moreover, based on the output of both pressures gauges Sa and Sc, automatic control can be performed using process control unit 6.

(1-3) Operate inert gas supply unit instead of the decompression process unit, and fill pipe La with inert gas. In concrete terms, close on-off valve Vf, open on-off valve Vg, and pipe La can be filled with inert gas in decompressed state via pipes Lg and Lc by introducing inert gas. The state of stability can be verified using pressure gauges Sa and Sc. Moreover, based on the output of both pressures gauges Sa and Sc, automatic control can be performed using process control unit 6. (1-4) Repeat processes (1 -2) and (1 -3) for the predetermined number of times Mo, and evacuate feed gas inside pipe La. Namely, purging can be carried out sufficiently by one "decompression-feed gas" process provided small molecules of hydrogen having absorptive properties are used; however, several "decompression-feed gas" processes are necessary when large molecules of hydrogen having absorptive properties such as NHb and SiH4 are used.

(1-5) Close on-off valve Vc as pipe La is filled with inert gas. This makes the formation of the gas isolated state on the upstream side comprising filled container 1 and pipe Lo possible concomitantly with the purging of pipe La.

(1-6) Remove one end of container valve 1a and pipe La. This makes the removal of the filled container 1 possible. (1-7) Remove filled container 1 from mounting unit 2.

(2) Process of installing the new filled container using the inventive system A

The process of installing the new filled container using the inventive system A can be carried out following the steps below. (2-1 ) Mount new filled container on the mounting unit. (2-2) Connect one end of pipe La to container valve 1a. (2-3) Open on-off valve Vc, operate decompression unit of the purging process unit 5, and evacuate gas inside pipe La. (2-4) Close on-off valve Vc and open on-off valve Va, and fill pipe La with the feed gas preserved inside pipe Lo. (2-5) Close on-off valve Va and open on-off valve Vc, operate decompression unit of the purging process unit 5, and evacuate gas inside pipe La.

(2-6) After repeating processes (2-4) and (2-5) for the predetermined number of times Na, fill pipe La with the feed gas preserved inside pipe Lo. (2-7) Close on-off valve Vc as pipe La is filled with inert gas. This makes the formation of the gas isolated state on the upstream side comprising filled container 1 and pipe Lo possible concomitantly with the purging of pipe La.

The purging process amount of feed gas can be reduced to a great extent by carrying out the purging process described above. Namely, the capacity of pipe La necessitating purging is minimized by installing pipe Lo having the predetermined capacity between container valve 1a and valve 3, and at the same time a reliable purging process can be carried out using a small amount of feed gas by purging pipe La using feed gas present inside pipe Lo.

The number of repetitions Na is analyzed hereinafter. When the residual pressure of the filled container 1 before the purging process is Po, the set pressure of the pressure valve 3 is Ps, the capacity of the pipe Lo comprising valves Va and Vb is Go, the capacity of the pipe La comprising Vc is Ga, the higher limit of the number of repetitions Na is preferably determined by means of Equation 1

Na < log (Po/Ps) / (Go + Ga) ... (Equation 1)

Namely, for continuing the supply of gas in stable state, the pressure on the primary side of the decompression valve 3 is preferably kept under the set pressure Ps and the supply of feed gas begins; after the purging of pipe La carried out by means of feed gas existing inside pipe Lo, the pressure of pipes La, Lo, and Lb was set to a value above the set pressure Ps of decompression valve 3. In concrete terms, the appropriate data of the number of repetitions Na of the secondary purging process can be calculated from the residual pressure Po of the filled

container before the purging process, and contents Go and Ga of pipe Lo and pipe La. See details below.

Moreover, the pressure of the purge gas decreases gradually from the pressure Po of the feed gas inside pipe Lo before the purging process begins, by means of repeating the purge. Namely, the ambient pressure corresponding value of the processing amount per one purging of feed gas decreases gradually due to the repetition of the purging. Consequently, the purging processing amount of the feed gas can be reduced to a great extent by using the method of purging process of the inventive system, compared to the previous method of purging by means of feed gas from the previous filled container 1. Particularly in cases such as the case of high pressure gas filled into the filled container 1 in gaseous state, or the case the charge pressure decreases gradually due to the supply process of the feed gas, the pressure Po of the feed gas inside pipe Lo before starting the purging process decreases to a great extent from the internal pressure of the filled container 1 after starting the purging process (high pressure conditions are achieved after replacing the container), yielding the decrease to an even larger extent of the purging processing amount of the feed gas.

Figure 1 shows the case when pipe Lo is formed as a pipe having valves Va and Vb at both ends; however, several structures formed of pipes Lo1 and Lo2 or Lo3 and Lo4, as shown in Figure 2 (A) and (B) are also preferred. For example, by carrying out the above-described purging by means of pipes Lo1 and Lo3 (the pressure of the feed gas inside

decreases due to the purging process) and starting supply of gas through pipe Lo2 or Lo4 after completing the purging process, gas can be supplied without the decrease in pressure of the feed gas inside pipe Lo. In Figure 2 (A), the capacity of each pipe increases because pipe La is connected via two on-off valves Va1 , Va2, and pipe Lb is connected via two on-off valves Vb1 , Vb2; in Figure 2 (B), the capacity of each pipe increases because connection space is necessary for connecting on-off valve Va and on-off valves Va3, Va4, and for connecting on-off valve Vb and on-off valves Vb3, Vb4. However, as either pipe Lo1 or Lo2, showing little or no pressure decrease upon starting gas supply, can be chosen as supply flow paths, the overall evacuated supply gas amount can be reduced by means of the purging process. (3) Process of supplying gas to process device 4

The process of supplying gas to process device 4, as the second step of the gas supply method using the inventive system A can be carried out following the steps below.

(3-1 ) Open container valve while the on-off valves Va-Ve are closed. (3-2) Open on-off valves Va, Vb, and Vd in order at predetermined time intervals. The predetermined time intervals are the times the internal pressure of pipes Lo and Lb respectively become the internal pressure of the filled container 2, and can be preset according to the capacity of each pipe. Moreover, using the pressure gauge Sb on the secondary side of decompression valve 3, the fact that its pressure does not fluctuate is preferably verified.

(3-3) Supply feed gas from the filled container to the process device 4 via the piping unit.

By means of such a purging process, the pressure of pipes La, Lo, and Lb corresponding to the primary side of the decompression valve 3 is kept above set pressure Ps of decompression valve 3 and below the pressure inside filled container 1 , and gas can be supplied to processing device 4. However, in cases such as high pressure gas filled inside filled container 1 in gaseous state, the difference between the pressure on the primary side of the decompression valve 3 immediately before the purging process and the pressure inside filled container 1 immediately before the supply process can become very big. When the container valve is opened under such circumstances and high pressure is suddenly applied to decompression valve 3, the controlled pressure thereof can be influenced. At that point, the buffering feature of pipe Lo can be used efficiently, and at the same time the application of such high pressure inside filled container 1 directly to decompression valve 3 can be moderated by controlling on-off valves Va and Vb and opening on-off valves Va, Vb and Vd in order at predetermined time intervals. The time intervals for opening the on-off valves can be set according to each pressure and the capacity of pipes La, Lo.

Analysis A of the evacuated feed gas

The total amount of feed gas evacuated by means of the above-described process and the total amount of feed gas evacuated by means of the previous

method of replacing the gas comprised inside pipe Lo are analyzed and compared. The purging process in case a new filled container is installed is analyzed here.

(a) Analysis conditions (a-1 ) Capacity of each pipe

Capacity of pipe La (7.53 mm internal diameter, 0.3 m length):

0.01336 L

Capacity of pipe Lo (7.53 mm internal diameter, 2.5 m length):

0.11133 L Capacity of pipe Lb (7.53 mm internal diameter, 0.1 m length):

0.00445 L

Capacity of pipe Ld (7.53 mm internal diameter, 0.2 m length):

0.00891 L

(a-2) Pressure conditions Pressure of the decompression valve secondary side: 0.5 MPa

Pressure of the decompression valve primary side before the purging process: 1 MPa

Internal pressure of the new filled container: 10 MPa

(b) Purging process method (b-1 ) Previous method not using decompression process

Pipe Lo' corresponding to pipe Lo is installed, without valves at both ends and communicating with pipes La and Lb. During the removal process (i) of the filled container 1 , the pipes (La + Lo' + Lb + Ld) were purged by means of inert gas at ambient pressure. During the installation process (ii) of the new filled container 1 , an

amount double that of the capacity of pipe was purged by means of feed gas at charge pressure. (b-2) Previous method using decompression process

Lo' is similar to (b-1 ). During process (i), the pipes (La + Lo' + Lb + Ld) were purged by means of inert gas after decompression.

During process (ii), after decompression, purging was carried out by means of feed gas at pipe pressure before the purging process, and after repeating decompression, purging was carried out by means of feed gas at charge pressure. (b-3) Using inventive system A

For purging by means of feed gas, the total processing amounts (ambient pressure conversion) upon filling pipe La (and pipe Lo) once with feed gas after decompression and upon filling with feed gas after repeating decompression and carrying out the purge were analyzed and compared.

(c) Results: Comparison of total amounts of feed gas

(c-1 ) Previous method not using decompression process Processing amount of feed gas in process (i):

(0.01336 + 0.11133 + 0.00445) x 10 + 0.00891 x 5 = 1.336 L

Processing amount of feed gas in process (ii):

{(0.01336 + 0.11133 + 0.00445) x 100 + 0.00891 x 5} x 2 = 25.837

(c-2) Previous method using decompression process Processing amount of feed gas in process (i):

(0.01336 + 0.11133 + 0.00445) x 10 + 0.00891 x 5 = 1.336 L Processing amount of feed gas in process (ii):

{(0.01336 + 0.11133 + 0.00445) x 10 + 0.00891 x 5} +

{(0.01336 + 0.11133 + 0.00445) x 100 + 0.00891 x 5} =

1.336 + 12.959 = 14.295 (c-3) Using inventive system A

Processing amount of feed gas in process (i):

0.01336 x 10 = 0.1336 L

Processing amount of feed gas in process (ii):

0.01336 x 10 x 0.11133 / (0.01336 + 0.11133) = 0.1193 L

Summary

The results of the analysis/comparison are shown in Table 1 below. These results reveal that 1/100 -1/60 processing amount of feed gas is sufficient when using the inventive system A, compared to conventional methods.

Table 1

Another configuration example of the.inventive gas supply system

Figure 3 is a schematic illustration of another configuration example (inventive system B) of the inventive gas supply system. The structure of the inventive system B is basically similar to the structure of the inventive system A; however, on-off valve Vd is located on the secondary side of the decompression valve 3, and pipe Le from the purging process unit 5a, is connected via pn-off valve Ve to pipe Ld connecting on-off valve Vd and decompression valve 3. Pipe Le is connected together with pipe Lc to valves Vf and Vg onside the purging process unit 5a, and together with pipe La performs the decompression process of pipe Ld and pipe Lb and the inert gas supply.

For system maintenance and verification, the inventive system B may necessitate gas isolation with the piping from container valve 1a until the process device 4 after the flow path comprising part of the secondary side of decompression valve 3 (the flow path until on-off valve Vd in Figure 3). The inventive system B caries out gas isolation with the piping until process device 4, and at the same time pipe Lo is located in the middle the piping from container valve 1a to decompression valve 3, the purging processing amount of the feed gas can be reduced to a great extent by forming a system connecting the decompression process unit and the inert gas supply to the flow path on the upstream side and downstream side of pipe Lo, making the purging of both flow paths possible simultaneously or alternately.

Supply method using the inventive system B

The purging process can be implemented by means of the processes below, as the first step of the gas supply method using the inventive system B. In concrete

terms, inventive system B is similar to inventive system A, and the description of the gas supply process in step 2 is omitted. Moreover, the case when the decompression process and the process of supplying inert gas or feed gas are carried out simultaneously as against pipe La and pipe Ld and pipe Lb is described hereinafter.

(1 ) Process of removing the filled container using the inventive system B The process of removing the filled container, at the time of container replacement, can be carried out following the steps below, using the inventive system B shown in Figure 3.

(1 -1 ) Close container valve 1 a and valves Va-Vg. (1-2) Open valves Vc and Ve and perform the decompression process of the purging process unit 5, and evacuate the gas inside pipes La and Ld and Lb. In concrete terms, open valve Vf, and by activating gas ejector Fv, the pipes Lf and Lc and Le are decompressed via pipes La and Ld and Lb, and the gas containing the feed gas inside can be evacuated. The state of stability can be verified using pressure gauges Sa, Sb, and Sc. Moreover, based on the output of pressures gauges Sa, Sb, and Sc, automatic control can be performed using process control unit

6. (1-3) Operate inert gas supply unit instead of the decompression process unit, and fill pipes La and Ld and Lb with inert gas. In concrete terms, close valve Vf, open valve Vg, and pipes La and Ld and Lb can be filled with inert gas in decompressed state via

pipes Lg and Lc and Le by introducing inert gas. The state of stability can be verified using pressure gauges Sa, Sb, and Sc. Moreover, based on the output of pressures gauges Sa, Sb, and Sc, automatic control can be performed using process control unit 6.

(1-4) Repeat processes (1 -2) and (1-3) for the predetermined number of times Mo, and evacuate feed gas inside pipes La and Ld and Lb. Namely, sufficient purging can be carried out by one "decompressed gas-feed gas" process provided small molecules of hydrogen having absorptive properties are used; however, several "decompressed gas-feed gas" processes are necessary when large molecules of hydrogen having absorptive properties such as NH3 and SiHk are used.

(1-5) Close valves Vc and Ve as pipes La and Ld and Lb are filled with inert gas. This makes possible the formation of the gas isolated state on the downstream side comprising filled container 1 and pipes Lo by means of pipe La and the formation of the gas isolated state on the upstream side comprising filled pipe Lp and pipe Lo by means of pipes Ld and Lb concomitantly with the purging of pipes La and Ld and Lb.

(1-6) Remove one end of container valve 1a and pipe La. This makes the removal of the filled container 1 possible.

(1 -7) Remove filled container 1 from mounting unit 2.

(2) Process of installing the new filled container using the inventive system B

The process of installing the new filled container using the inventive system B can be carried out following the steps below. (2-1 ) Mount new filled container on the mounting unit. (2-2) Connect one end of pipe La to container valve 1a. (2-3) Open valves Vc and Ve, operate decompression unit of the purging process unit 5, and evacuate gas inside pipes La and Ld and Lb. (2-4) Close valves Vc and Ve and open valves Va and Vb, and fill pipes

La and Ld and Lb with the feed gas preserved inside pipe Lo. (2-5) Close valves Va and Vb and open valves Vc and Ve, operate decompression unit of the purging process unit 5, and evacuate gas inside pipes La and Ld and Lb. (2-6) After repeating processes (2-4) and (2-5) for the predetermined number of times Nb, fill pipes La and Ld and Lb with the feed gas preserved in pipe Lo.

(2-7) Close valves Vc and Ve as pipes La and Ld and Lb are filled with feed gas. This makes possible the formation of the gas isolated state on the downstream side comprising filled container 1 and pipes Lo by means of pipe La and the formation of the gas isolated state on the upstream side comprising filled pipe Lp and pipe Lo by means of pipes Ld and Lb concomitantly with the purging of pipes La and Ld and Lb.

By carrying out the above-described purging process, the purging processing amount of the feed gas during the purging process

comprising gas isolation of pipes La and Ld and Lb connected to both ends of pipe Lo can be reduced to a great extent. Namely, by installing pipe Lo having a set capacity between container valve 1a and decompression valve 3, the capacity of pipe La necessitating purging and of pipes Ld and Lb is minimized, and reliable purging can be carried out by means of a small amount of feed gas by using feed gas existing inside pipe Lo and carrying out purging of pipes La and Ld and Lb.

The number of repetitions Nb is analyzed hereinafter. When the residual pressure of the filled container 1 before the purging process is Po, the set pressure of the pressure valve 3 is Ps, the capacity of the pipe Lo comprising valves Va and Vb is Go, the capacity of the pipe La comprising on-off valve Vc is Ga, and the capacity of the pipe Lb comprising valves Vd and Ve is Gb, the higher limit of the number of repetitions Na is preferably determined by means of Equation 2.

Nb < log (Po/Ps) / (Go + Ga + Gb) ... (Equation 2)

Namely, as the amount of feed gas existing inside pipe Lo is limited, the number of processes such as the purging process is limited in the purging of the primary side and secondary side of decompression valve 3 using the feed gas or in the gas isolation. In addition, after the purging process, the pressure of pipes La, Lo, and Lb is preferably set above set pressure Ps of decompression valve 3. In concrete terms, In concrete terms, the appropriate data of the number of repetitions Nb of the

secondary purging process can be calculated from the residual pressure Po of the filled container before the purging process, contents Go of pipe Lo, contents Ga of pipe La, and contents Gb of pipe Ld and pipe Lb. See details below.

Moreover, at this point, the number of purges of pipe Ld and pipe Lb can be made smaller than the number of purges of pipe La because the flow path is practically not polluted and attention is given to gas isolation, and the processing amount of feed gas evacuated through purging can be further decreased. Namely, the higher limit of the number of repetitions

Nb is preferably determined by means of Equation 3 instead of Equation 2.

Nb ≤ log (Po/Ps) / (Go + Ga + a x Gb) ... (Equation 3)

Here, a is the ration in case the number of purging processes of the pipe Ld and the pipe Lb is lower than the number of purging processes of the pipe La, and the former was set to 1. The purging processing amount of the evacuated feed gas can be reduced even more than the case when Equation 2 is used.

(3) Process of supplying gas to process device 4

The process of supplying gas to process device 4, as the second step of the gas supply method using the inventive system B can be carried out following the steps below, similarly to system A.

(3-1 ) Open container valve while the valves Va-Ve are closed. (3-2) Open valves Va, Vb, and Vd in order at predetermined time intervals.

(3-3) Supply feed gas from the filled container to the process device 4 via the piping unit.

Analysis B of the evacuated feed gas

The total amount of feed gas evacuated by means of the above-described process and the total amount of feed gas evacuated by means of the previous method of replacing the gas comprised inside pipe Lo are analyzed and compared.

(a) Analysis conditions

Omitted because the conditions are similar to those in the above- described [Analysis A of the Evacuated Feed Gas] (b) Purging process method

(b-1 ) and (b-2) are omitted because they are similar to those in the above-described [Analysis A of the evacuated feed gas]. (b-3) Using inventive system B

For purging by means of feed gas, the total processing amounts (ambient pressure conversion) upon filling pipe La (and pipe Lo), Ld, Lb once with feed gas after decompression and upon filling with feed gas after repeating decompression and carrying out the purge were analyzed and compared, (c) Results: Comparison of total amounts of feed gas

(c-1 ) and (c-2) are omitted because they are similar to those in the above-described [Analysis A of the Evacuated Feed Gas]. (c-3) Using inventive system B

Processing amount of feed gas in process (i):

(0.01336 + 0.00445) x 10 + 0.00891 x 5 = 0.2226 L Processing amount of feed gas in process (H):

(0.01336 + 0.00445) x (10 x 0.11133 - 0.00891 x 5) / (0.01336 + 0.11133 + 0.00445) + 0.00891 x 5 = 0.1474 L

Summary

The results of the analysis/comparison are shown in Table 1 below. These results reveal that 1/70-1/40 processing amount of feed gas is sufficient when using the inventive system B, compared to conventional methods.

Table 2

Alternative embodiment B1 of the inventive system B

Figure 4 shows the configuration example "Alternative Embodiment B1" that can perform "decompression-inert gas filling" and "decompression-feed gas filling" alternately via pipe La and pipes Ld, Ld as the alternative embodiment of the inventive system B. This configuration example is similar to that of the above- described system B; however, inside purging process unit 5, by comprising on- off valves VfI and Vf2 connected to the decompression process unit and on-off valve Vg1 and Vg2 connected to the inert gas supply unit, the decompression process and the inert gas supply can be switched on-off by means of on-off valve VfI and on-off valve Vg1 via pipe La, and at the same time it plays a role in the decompression process and the inert gas supply by means of on-off valve Vf2 and on-off valve Vg2 as against pipes Ld ₁ Lb .

In the "decompression-inert gas filling", the decompression process via pipe La is carried out simultaneously with the inert gas supply via pipes Ld, Lb, and inert gas supply via pipe La can be switched simultaneously to decompression process via pipes Ld, Lb. Moreover, in the "decompression-feed gas filling", decompression process via pipe La while on-off valve VfI is open can be carried out simultaneously with filling feed gas via pipes Ld, Lb while on-off valve Vb is open; filling feed gas via pipe La while on-off valve Vb is open can be carried out simultaneously with the decompression process via pipes Ld, Lb while on-off valve Vf2 is open. By performing the decompression function of gas ejector Fv and the supply function of the inert gas or the feed gas without increasing them, the hysteresis of the entire system is reduced, the influence of part variation on the control pressure of decompression valve 3 is reduced, and stabilized feed

gas can be supplied to process device 4. By operating on-off valves Vf 1 , Vf2 and on-off valves Vg1, Vg2, the decompression process and the inert gas supply can also be carried out simultaneously via pipe La and pipes Ld, Lb.

Alternative embodiment B2 of the inventive system B

Figure 5 shows the configuration example "Alternative Embodiment B2" that can perform "decompression-inert gas filling" and "decompression-feed gas filling" alternately via the upstream and downstream of the decompression valve 3 as the alternative embodiment of the inventive system B. This configuration example is similar to that of the above-described system B; however, purging processing unit 5 is connected to pipe Lb on the upstream side of decompression valve 3 and pipe Ld on the downstream side of said pipe via on- off valve Ve1 and on-off valve Ve2.

In the "decompression-inert gas filling", by opening on-off valve Vf connected to the decompression processing unit, the decompression process of pipe La can be carried out simultaneously with the decompression process via pipes Lb, Ld on both the upstream and downstream of decompression valve 3, and at the same time the inert gas supply in pipe La is carried out simultaneously with the inert gas supply via pipes Lb, Ld on both the upstream and downstream of decompression valve 3, by opening on-off valve Vg connected to the inert gas supply processing unit. Moreover, in the "decompression-feed gas filling", the decompression process of pipe La is carried out simultaneously with the decompression process via pipes Lb, Ld on both the upstream and downstream of decompression valve 3, by opening on-off valve Vf connected to the inert gas

supply processing unit, and at the same time feed gas ca be fed via pipe La by opening on-off valve Va and via pipes Ld, Lb via on-off valve Vb. By carrying out the decompression process from both sides of decompression valve 3 simultaneously and the supply of inert gas or feed gas, hysteresis of the decompression valve 3 is reduced, the variation factor of the control pressure of the decompression valve 3 is reduced, and stabilized feed gas can be supplied to process device 4.

Potential Industrial Applications A supply system for high pressure gases or liquefied gases mainly used for semiconductors or various manufacturing processes was described above; however, the present invention is not limited to such industrial applications, but can also be used for general liquefied gas supply systems such as gas supply facilities in hospitals.

Brief Description of the Drawings

Figure 1 is a schematic illustration of the basic configuration example of the inventive gas supply system.

Figure 2 is an explanatory drawing illustrating the configuration example of the inventive pipe Lo.

Figure 3 is a schematic illustration of another configuration example of the inventive gas supply system.

Figure 4 is a schematic illustration of the alternative embodiment of another inventive gas supply system.

Figure 5 is a schematic illustration of the alternative embodiment of another inventive gas supply system.

Figure 6 is a schematic illustration of further developments of test control system of the high pressure container.

Explanation of Codes 1 filled container

1 a container valve

2 mounting unit 3 decompression valve (pressure regulation unit)

4 process device (gas consumption facility)

5 purge operation unit

6 process control unit Fv gas ejector Lo, La-Lg, Lp pipes

Sa, Sb, Sc pressure sensors Va-Vg valves