Pressure reduction system, device and method for high-pressure gas delivery

Abstract

An apparatus for depressurizing a pair of accumulators to supply high pressure gas includes a tank in fluid communication with each one of the pair of accumulators for receiving vapor from the pair of accumulators for storage and metering the vapor to a remote location other than the pair of accumulators and the external atmosphere, a first fluid connection including a first valve assembly interconnecting the tank and a first accumulator of the pair of accumulators, and a second fluid connection including a second valve assembly interconnecting the tank and a second accumulator of the pair of accumulators, wherein the first fluid connection having the first valve assembly and the second fluid connection having the second valve assembly are each constructed and arranged to deliver vapor from a corresponding one of the first accumulator and the second accumulator to the tank during alternating intervals. Related methods and systems are also provided.

Description

Technical Field

[0001] Background of the Invention The present embodiment relates to an apparatus and method for supplying high-pressure CO2 from two or more containers known as accumulators, and more particularly to such an apparatus and method used in the electronics industry (e.g., semiconductor industry).

Background Art

[0002] An accumulator used in the electronics industry is a device that includes a tank or container configured to store a fluid at a pressure greater than atmospheric or ambient pressure and, in many applications, at a very high pressure. In the electronics industry, such fluids stored in accumulators can include liquid carbon dioxide (CO2) and liquid nitrogen (N2), and can ultimately be phase-changed to the gas phase for use in applications such as cleaning electronic devices and optical components and as an inert gas proximate to electronic devices and optical components.

[0003] Due to economies of scale, the use of a pair of accumulators is recommended in the electronics industry for applications that require high-pressure gaseous CO2. This is because one of the pair of accumulators, whose CO2 product has been depleted, needs to be depressurized before refilling, while the other accumulator of the pair continues to operate. In the absence of other equipment used for such depressurization, some of the CO2 is released to the atmosphere during depressurization, and the undesirable activities contribute to greenhouse gas (GHG) emissions and the loss and waste of gaseous CO2 product.

[0004] Even if the gaseous CO2 lost in another way can be recycled and reused, in order to avoid unnecessary CO2 emissions, the known process of replenishing the pressure reducing accumulator cools the gas through a cooling system to reliquefy and recover the CO2 emission gas. Unfortunately, this known recovery process and related cooling system require a large installation area or platform in the processing facility, consume a large amount of energy and power to reliquefy and recover the CO2 emission gas, and incur related costs to reliquefy the CO2 gas within a specific time allocated for the depressurization of the accumulator. This time limit is significant and thus troublesome. Because the replenishment of the pressure reducing accumulator needs to make a judgment at just the right time for the other accumulator to take over the operation when the other accumulator has exhausted the CO2 product.

[0005] Figure 1 shows an example of a known system and method in the semiconductor industry for collecting, reliquefying, and pressurizing CO2 gas.

[0006] The known system 10 includes a pair of accumulators 12, 14, and each accumulator contains liquid CO2 supplied from a source 16 of liquid CO2 via a pipe 18 that is divided into a separation branch 20 or pipe fluidly connected to the accumulator 12 and a separation branch 22 or pipe fluidly connected to the accumulator 14, respectively.

[0007] The known system 10 is configured to maintain a continuous supply of high-pressure gaseous CO2, and the operating cycle of the system replenishes one of the accumulators 12, 14 while the other accumulator meters and supplies the CO2 product for industrial and / or commercial use. Examples of the operating cycle and corresponding "modes" of the known system 10 are presented later in Table 1.

[0008] Further explanation will be given for FIG. 1 in conjunction with Table 1. The high-pressure gas delivery system is shown generally at 10. As shown in FIG. 1, the first accumulator 12 is configured and arranged to deliver high-pressure gaseous CO2 via fluid connections 28, 32, 95 or pipes, while the second accumulator 14 is configured and arranged to deliver high-pressure gaseous CO2 via fluid connections 30, 32, 95 or pipes. The first accumulator 12 delivers high-pressure gaseous CO2 via fluid connections 28, 32, 95 or pipes, while the second accumulator 14 is offline from the delivery service and instead is replenished with liquid CO2 from a storage tank 16 or container of a bulk supply containing liquid CO2. However, before the accumulator 14 can be replenished, it is first necessary to depressurize the accumulator 14. The depressurization of the accumulator 14 is as follows.

[0009] The accumulator 14 is depressurized to the container 26 via fluid connections 39, 44, 45 by opening valves 59, 47. The CO2 vapor from the accumulator 14 is condensed to a liquid by passing through a heat exchanger in the condenser 24 which is in further fluid communication with a cooling unit, and then the liquefied CO2 is delivered to and stored in the container 26 via fluid connection 45 or pipes. The condensation of the CO2 vapor is achieved by an external cooling unit (not shown, see FIG. 1). Once the accumulator 14 is completely depressurized to the desired or selected pressure set point, the liquid CO2 temporarily stored in the container 26 is returned and delivered to the accumulator 14 via fluid connection 42 or pipes via fluid connection 46 or pipes by opening valve 57 at fluid connection 42. Further, the accumulator 14 is replenished from the liquid CO2 supplier 16 to the desired or selected level set point, and the fluid connection 18 or pipes from the CO2 storage container 16 delivers a CO2 supply flow to the accumulator 14 via fluid connection 22 or pipes. The accumulator 14 is heated (e.g., by the electric heater 50) to evaporate the liquid CO2 and pressurize the accumulator 14 to the delivery pressure for the gaseous CO2 flow to be generated by the system 10 and delivered via pipe 30. The delivery pressure at the outlet 95 of the system 10 is in the range of 600 psig to 1000 psig.

[0010] The condenser 24 needs to condense the CO2 vapor from the accumulator 14 into a liquid during a specific time period assigned to the pressure reduction. In other words, when the accumulator 12 approaches depletion of the CO2 supply and needs to be taken offline for pressure reduction and replenishment, the factory operator does not want to be in a paused state during the operation of waiting for the accumulator 14 to be replenished. Therefore, the condenser 24 includes a large heat exchanger and a cooling unit required to meet this time constraint and the increased cooling requirements. That is, the pressure reduction time is set to enable sufficient time to fill and pressurize the accumulator 14 before the accumulator 12 depletes the liquid CO2 supply. This choreography between the accumulators 12, 14 and each pipe and valve is necessary to deliver a continuous and reliable supply of gaseous CO2 from the outlet 95 for later factory use. However, as described above, the known system 10 of FIG. 1 requires a large amount of power and energy corresponding to the cooperation between the accumulators 12, 14 to provide a reliable source of gaseous CO2 at the system outlet 95.

[0011] When the first accumulator 12 is taken offline from the delivery service and instead the liquid CO2 is replenished to the first accumulator 12 from a large supply storage tank 16 or container containing liquid CO2, a reversible process is performed.

[0012] The modes in the known system 10 for the accumulators 12, 14 are shown in Table 1 below and relate to FIG. 1.

[0013]

Table 1

Summary of the Invention

Means for Solving the Problems

[0014] Summary of the Invention In contrast to the known systems described above, embodiments of the present invention require condensers and cooling units of a smaller configuration with a reduced installation area in a factory or facility. As a result, in this embodiment, all of the CO2 released during the depressurization of the accumulator is collected and recovered for subsequent use by the accumulator, thereby reducing the capital and operating costs associated with the cooling components of the system.

[0015] Accordingly, a depressurization system is provided herein that generates high-pressure gas (e.g., CO2 gas) from a pair of accumulators, the system including a gas buffer tank assembly consisting of a gas buffer tank for the pair of accumulators. Further, the gas buffer tank assembly includes a pair of pressure relief valves for each accumulator such that the depressurization from both accumulators to the gas buffer tank and from the gas buffer tank to the condenser facilitates the overall system depressurization. By this embodiment, the pressures of the gas buffer tank and each accumulator are equalized, thereby temporarily holding a portion of the intermediate gas from each accumulator in the gas buffer tank before the intermediate gas can be condensed and reliquefied for reintroduction into the same accumulator.

[0016] In a particular embodiment described herein, an apparatus for depressurizing a pair of accumulators to supply high-pressure gas, the apparatus comprising a tank in fluid communication with each one of the pair of accumulators that receives vapor from the pair of storage accumulators and meteringly supplies the vapor to a remote location other than the pair of accumulators and the external atmosphere, a first fluid connection including a first valve assembly interconnecting the tank and the first accumulator of the pair of accumulators, and a second fluid connection including a second valve assembly interconnecting the tank and the second accumulator of the pair of accumulators, wherein the first fluid connection having the first valve assembly and the second fluid connection having the second valve assembly are each configured and arranged to deliver vapor from the corresponding one of the first accumulator and the second accumulator to the tank during alternating intervals.

[0017] In a particular embodiment of the apparatus, the remote location includes a condenser that condenses the vapor into a liquid.

[0018] In certain embodiments of the apparatus, the apparatus further includes a container tank in fluid connection with a condenser that receives and stores liquid until required by a first accumulator and a second accumulator.

[0019] In certain other embodiments of the apparatus, the vapor is derived from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen.

[0020] Provided is a method of depressurizing a pair of accumulators to supply high-pressure gas, the method including: (a) withdrawing a portion of the vapor from a first accumulator of the pair of accumulators to a tank; (b) equalizing the pressures of the first accumulator and the tank to temporarily hold a portion of the vapor as intermediate gas from the first accumulator in the tank; (c) supplying the intermediate gas to a remote location other than the pair of accumulators and the atmosphere; (d) condensing the intermediate gas to a liquid at the remote location; and (e) returning the liquid to the first accumulator.

[0021] In certain embodiments, the method includes supplying high-pressure gas from a second accumulator of the pair of accumulators during steps (a) through (e).

[0022] In certain other embodiments, the method further includes storing the liquid at the remote location before returning the liquid to the first accumulator.

[0023] In certain other embodiments, the method includes the vapor being derived from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen.

[0024] Brief Description of the Drawings For a more complete understanding of the present invention, reference should be made to the following description of exemplary embodiments considered in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

[0026] **Detailed Description of the Invention** Before explaining the embodiments of the invention in detail, it should be noted that the present invention is capable of other embodiments and can be implemented or executed in various ways. Therefore, if any, the present invention should not be limited to the application to the details of the configuration and arrangement of the exemplary components in the accompanying drawings. Furthermore, the expressions or terms used herein are for the purpose of explanation and not for limitation.

[0027] In the following description, terms such as horizontal, upright, vertical, upper, lower, downward, etc. should be used only for clearly explaining the present invention and should not be considered as limiting terms. If any, the drawings are for the purpose of explaining the present invention and are not intended to be proportional to the actual size.

[0028] Here, the reference to "fluid connection part" means a conduit, pipe, passage, etc. that provides fluid delivery or fluid communication, and it can be considered to include a plurality of such elements.

[0029] FIGS. 2 and 3 will be described. Here, the embodiment of the invention includes a pressure reducing system 100 having, among other elements, a gas buffer tank assembly 102 (hereinafter also referred to as "buffer tank assembly 102"). The buffer tank assembly 102 can be retrofitted to the original configuration having a known system 10 for cooperating with the accumulators 12, 14, or can have the original configuration. The accumulators 12, 14 for temporarily storing CO2 vapor (Corresponding to the "pair of accumulators" described in the claims, accumulator 12 corresponds to the "first accumulator", and accumulator 14 corresponds to the "second accumulator". The same applies to the drawings.)Equalize the pressure between them and divide the pressure reduction stage into two separate stages. If not all of the CO2 gas is necessarily generated during pressure reduction from each of the accumulators 12 and 14, the buffer tank assembly 102 collects a portion. The buffer tank assembly 102 includes a gas buffer tank 104 as shown in FIGS. 2 and 3. (Corresponding to the "gas buffer tank" described in the claims. The same applies to the drawings.) That is, for accumulator 12, the buffer tank assembly 102 includes the gas buffer tank 104, the fluid connection 106 or the pipe and valve 108. (Valve 108 corresponds to the "first valve assembly" described in the claims. The same applies to the drawings.) For accumulator 14, the buffer tank assembly 102 includes the gas buffer tank 104, the fluid connection 206 or the pipe and valve 208. (Valve 208 corresponds to the "second valve assembly" described in the claims. The same applies to the drawings.) Including.

[0030] An embodiment of the pressure reduction system 100 is a high-pressure gas delivery system and is different from the known system 10 of FIG. 1 by the addition of a gas buffer tank 104 and the corresponding piping and valves (valve assemblies) to each of the accumulators 12 and 14. The system 100 is configured and arranged to maintain a continuous supply of high-pressure gaseous CO2, set the operating cycle of the buffer tank assembly 102, replenish the first of the accumulators 12 and 14, while the second of the accumulators meteringly supplies the CO2 gas product. In this way of configuration and operation, there is no delay, interruption or downtime during on-demand CO2 supply, and a much smaller condenser and cooling unit installation area or platform than that required for the known system 10 is required for the pressure reduction of the accumulators 12 and 14. Examples of the operating cycle and the corresponding "modes" are presented later in Table 2.

[0031] A high-pressure gas delivery system is shown generally at 100. A first accumulator 12 delivers high-pressure gaseous CO2 to an outlet 95 for use in a gas application via fluid connections 28, 32 or a pipe, while replenishing a second accumulator 14 from a large supply of liquid CO2 16. The second accumulator 14 needs to be replenished before the CO2 in the first accumulator 12 is depleted and be ready to assume operation. First, it is necessary to depressurize the accumulator 14 before it can be replenished with liquid CO2. The depressurization of the accumulator 14 is carried out in two stages. In the first stage, first, the accumulator 14 is depressurized to the gas buffer tank 104 of the buffer tank assembly 102 for a time such that the pressures of the accumulator 14 and the gas buffer tank 104 are equalized to temporarily store a portion of the CO2 vapor in the gas buffer tank 104. In the second stage, next, the accumulator 14 is completely depressurized to a container 26 via fluid connections 39, 44 to a condenser 24 that condenses the CO2 vapor into a liquid (Corresponding to the "receiver tank" described in the claims. The same applies to the drawings.) Such condensation is achieved by an external cooling unit (not shown), and the condensed liquid is supplied to the container 26 via a fluid connection 45 from the condenser 24 to the container. Once the accumulator 14 is completely depressurized to a desired pressure set point, the liquid CO2 temporarily stored in the container 26 is returned and delivered to the accumulator 14 via fluid connections 46, 42 by opening a valve 57. Further, the accumulator 14 is replenished or filled to a desired level set point using additional liquid from the liquid CO2 supplier 16, and a supply stream 18 containing liquid CO2 is introduced into the accumulator 14 via a fluid connection 22. The accumulator 14 is heated (e.g., by an electric heater 50) to evaporate the liquid CO2 stored in the accumulator and pressurize the accumulator 14 to a delivery pressure for the gas CO2 stream to be generated by the system 100 and delivered via fluid connections 30, 32 to the outlet 95 for use. The delivery pressure at the outlet 95 is in the range of 600 psig to 1000 psig.

[0032] While accumulator 14 is being refilled and pressurized, gas buffer tank 104 is depressurized to container 26 via fluid connections 206, 39, 44, 45, and CO2 vapor is condensed to liquid by the heat exchanger in condenser 24. Such condensation is achieved by an external cooling unit (not shown but referenced) in communication with the heat exchanger of condenser 24. Further, liquid CO2 is temporarily held in container 26 until the next cycle, and the liquid CO2 is sent to accumulator 12 via fluid connections 46, 40 or a pipe after accumulator 12 has reached the depressurization stage.

[0033] Before completely depressurizing accumulator 14, by first equalizing the pressure between accumulator 14 and gas buffer tank 104, the amount of CO2 vapor to be condensed in condenser 24 during this stage is significantly less than the amount generated in known system 10. By temporarily holding a portion of the CO2 vapor in gas buffer tank 104, the process of condensing the CO2 vapor can be extended over a longer time frame, thereby reducing the cooling requirements of condenser 24 instead of being strictly time - constrained to the exact time allotted to depressurize accumulator 14 as required in known system 10. Depressurizing gas buffer tank 104 and condensing the corresponding CO2 vapor is done during the filling and pressurizing step of accumulator 14. Next, this allows the cooling unit to operate continuously or substantially continuously, avoiding frequent cycling.

[0034] The modes in the embodiment of system 100 for accumulators 12, 14 are shown in Table 2 below, with reference to FIGS. 2 and 3.

[0035]

Table 2

[0036]

Table 3

[0037] Therefore, system 100 is more economical than the known system 10 for reducing the size of the cooling unit and the condenser 24.

[0038] The pressure reduction cycle steps for accumulators 12, 14 and the gas buffer tank 104 of the buffer tank assembly 102, and the cooperation between accumulators 12, 14 and the gas buffer tank 104 of the buffer tank assembly 102 can be summarized as follows. 1. Equalize the pressures of accumulators 12, 14 and the gas buffer tank 104. 2. Depressurize the accumulator / reliquefy CO2 and fill the container 26. 3. Fill from the container to the accumulator. 4. Fill from the liquid CO2 supplier 16 to the accumulator and start to depressurize the gas buffer tank 104 / reliquefy and fill the container 26. 5. Pressurize the accumulator with each heater 48, 50. 6. Complete the depressurization of the gas buffer tank 104 (now partially fill the container 26 with CO2 liquid), and wait. 7. When the second accumulator is exhausted, switch and meteringly supply high-pressure CO2 from the first accumulator. 8. Start the pressure reduction cycle in the second accumulator. 9. Repeat.

[0039] The gas buffer tank 104 reduces the amount of CO2 gas exiting accumulators 12, 14 during depressurization of accumulators 12, 14, gives more time, and reliquefies the CO2 gas through the condenser 24 and the cooling unit. As a result of the additional time from the gas buffer tank 104, the size of the condenser 24 - cooling unit and the associated installation area are significantly reduced, and thus the associated capital and operating costs of system 100 are also reduced. This embodiment provides a cost-effective solution for collecting all CO2 gas during depressurization to (i) avoid loss of CO2 product, (ii) avoid increase in GHG emissions, and (iii) reduce the size of the condenser / cooling unit that condenses CO2 vapor.

[0040] Manual valves 71 to 93 (odd numbers) are provided for shutting off and partially closing the corresponding fluid connections or pipes, adjusting the timing of the steam and liquid delivered through each system 10, 100, and can include one or more manual valves depending on the application of the system.

[0041] This present embodiment can be applied to other liquid products (e.g., liquid nitrogen or LIN) using the same devices and processes described herein, heating the liquid in a reservoir or container to deliver high-pressure gas, and recovering and using any gas or vapor in a cost-effective manner released in another way.

[0042] Even if the condenser 24 with a heat exchanger and a cooling unit is not added, the gas buffer tank 104 significantly reduces the amount of released gas during decompression.

[0043] The embodiments described herein are merely illustrative, and those skilled in the art can make changes and modifications without departing from the spirit and scope of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as defined by the appended claims. The above-described embodiments should be understood to be combinable as well as alternative.

Claims

1. An apparatus for depressurizing a pair of accumulators to provide high-pressure gas, A gas buffer tank fluidly connected to each of the pair of accumulators, which receives vapor from the pair of accumulators for storage and distributes the vapor to a condenser that condenses the vapor into a liquid other than the pair of accumulators and the external atmosphere, the gas buffer tank; A first fluid connection portion including a first valve assembly that interconnects the gas buffer tank and a first accumulator of the pair of accumulators; A second fluid connection portion including a second valve assembly that interconnects the gas buffer tank and a second accumulator of the pair of accumulators; A receiver tank fluidly connected to a condenser for receiving and storing the liquid until required by the first accumulator and the second accumulator, Each of the first fluid connection portion with the first valve assembly and the second fluid connection portion with the second valve assembly is configured and arranged to supply the vapor from the other of the first accumulator and the second accumulator to the gas buffer tank from the corresponding one while the high-pressure gas is being provided from one of the first accumulator and the second accumulator. Apparatus.

2. The vapor is from a liquid selected from the group consisting of liquid CO ２ and liquid nitrogen. The apparatus according to claim 1.

3. A method for depressurizing a pair of accumulators to provide high-pressure gas, (a) Taking out a part of the vapor from a first accumulator of the pair of accumulators to a gas buffer tank, (b) Equalizing the pressures in the first accumulator and the gas buffer tank to temporarily hold a portion of the vapor in the gas buffer tank as intermediate gas from the first accumulator; (c) Supplying the intermediate gas to a condenser other than the pair of accumulators and the atmosphere; (d) Condensing the intermediate gas to a liquid in the condenser; (e) Providing a receiver tank fluidly connected to the condenser for receiving and storing the liquid until required by the first accumulator; (f) Returning the liquid to the first accumulator. A method comprising these steps.

4. The method according to claim 3, further comprising providing high-pressure gas from a second accumulator of the pair of accumulators between steps (a) to (f).

5. The method according to claim 3, further comprising storing the liquid in the condenser before returning the liquid to the first accumulator.

6. The vapor is from a liquid selected from the group consisting of liquid CO ２ and liquid nitrogen. The method according to claim 3.

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