Pressure reduction system, apparatus and method for high pressure gas delivery

Abstract

An apparatus for depressurizing a pair of accumulators to provide high pressure gas, the apparatus comprising: a tank in fluid communication with each of a pair of accumulators for receiving vapors from the pair of accumulators for storage and dispensing of the vapors to a location remote from the pair of accumulators and an external atmosphere; a first fluid connection comprising a first valve assembly interconnecting the tank and a first accumulator of the pair of accumulators; a second fluid connection comprising a second valve assembly interconnecting the tank and a second accumulator of the pair of accumulators; wherein the first fluid connection of the first valve assembly and the second fluid connection of the second valve assembly are each configured and arranged to deliver vapors 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

Background Technology

[0001] This embodiment relates to an apparatus and method for supplying high-pressure CO2 from two or more containers called reservoirs, and particularly to such an apparatus and method used in the electronics industry, such as in the semiconductor industry.

[0002] A reservoir used in the electronics industry is a device comprising a tank or container configured to store fluids at pressures greater than atmospheric or ambient pressure, and for many applications, at significantly increased pressures. In the electronics industry, such fluids stored in reservoirs can include liquid carbon dioxide (CO2) and liquid nitrogen (N2), which are ultimately allowed to change phase to a gaseous phase for use, for example, in applications involving the cleaning of electronic and optical components and their vicinity as inert gases.

[0003] Economies of scale encourage the electronics industry to use a pair of accumulators for applications requiring high-pressure gaseous CO2. This is because, in order to refill one of the accumulators containing depleted CO2 products, the accumulator must be depressurized before refilling, while the other accumulator in the pair continues to operate. Without additional equipment for such depressurization, this results in a portion of the CO2 being released into the atmosphere during depressurization (an undesirable emission factor of greenhouse gas GHG), and leads to the loss and waste of gaseous CO2 products.

[0004] Known processes for refilling depressurized accumulators to avoid adverse CO2 emissions while still enabling the recycling and reuse of otherwise lost gaseous CO2 involve reliquefying and recovering the CO2 exhaust gas by cooling the gas through a refrigeration system. Unfortunately, this known recovery process and the associated refrigeration system require a large footprint or pad for processing facilities and consume significant amounts of energy and power to reliquefy and recover the CO2 exhaust gas, in addition to the associated costs of reliquefying the CO2 gas within the specific time allotted for depressurization of the accumulator. This time constraint is critical and therefore burdensome because the refilling of the depressurized accumulator must be completed in a timely manner to resume operation from the other accumulator in the pair when the other accumulator has exhausted its CO2 products.

[0005] Figure 1 Examples of known systems and methods for capturing, reliquefying, and pressurizing CO2 gas in the semiconductor industry are shown.

[0006] The known system 10 includes a pair of reservoirs 12, 14, each of which contains liquid CO2 supplied from a liquid CO2 source 16 via a conduit 18, which is divided into a separate branch 20 or conduit fluidly connected to reservoir 12 and a separate branch 22 or conduit fluidly connected to reservoir 14.

[0007] The known system 10 is configured to maintain a continuous supply of high-pressure gaseous CO2, wherein the system's operating cycle replenishes one of the reservoirs 12 and 14, while the other reservoir distributes the CO2 product for industrial and / or commercial use. Examples of the operating cycles and corresponding "modes" of the known system 10 are given in Table 1 below.

[0008] Still referencing Table 1 Figure 1 Known high-pressure gas delivery systems are generally shown as 10. For example... Figure 1 As shown, the first reservoir 12 is constructed and arranged to deliver high-pressure gaseous CO2 via fluid connections 28, 32, 95 or piping, while the second reservoir 14 is constructed and arranged to deliver high-pressure gaseous CO2 via fluid connections 30, 32, 95 or piping. While the first reservoir 12 is delivering high-pressure gaseous CO2 via fluid connections 28, 32, 95 or piping, the second reservoir 14 is taken offline from the delivery service and is instead refilled with liquid CO2 from a large-capacity supply storage tank 16 or container containing liquid CO2. However, before reservoir 14 can be refilled, reservoir 14 must first be depressurized. The depressurization of reservoir 14 is as follows.

[0009] By opening valves 59 and 47, the pressure in the accumulator 14 is reduced to that in the receiver 26 via fluid connections 39, 44, and 45. CO2 vapor from the accumulator 14 is condensed into liquid by a heat exchanger in the condenser 24, which is also in fluid communication with the refrigeration unit. The liquefied CO2 is then transported to and stored in the receiver 26 via fluid connection 45 or a pipe. The condensation of the CO2 vapor is facilitated by an external refrigeration unit (not shown, but...). Figure 1 (As mentioned in the text). Once the reservoir 14 is fully depressurized to the desired or selected pressure setpoint, the liquid CO2 temporarily stored in the receiver 26 is returned to the reservoir 14 via the fluid connection 46 or conduit by opening valve 57 in fluid connection 42. The reservoir 14 is also refilled from the liquid CO2 supply section 16 to the desired or selected level setpoint, wherein the CO2 feed stream from the CO2 storage container 16 is delivered to the reservoir 14 via fluid connection 22 or conduit through fluid connection 22. The reservoir 14 is heated, for example by electric heater 50, to evaporate the liquid CO2 and pressurize the reservoir 14 to the delivery pressure so that a gaseous CO2 stream can be generated by system 10 and delivered through conduit 30. The delivery pressure at outlet 95 of system 10 is in the range of 600 psig to 1000 psig.

[0010] Condenser 24 must condense the CO2 vapor from accumulator 14 into liquid during a specific time allocated for depressurization. In other words, when condenser 12 is nearly depleted of its CO2 supply and needs to be offline for depressurization and refilling, plant operators do not want any downtime in operation while waiting for accumulator 14 to be refilled. Therefore, condenser 24 includes a large heat exchanger and refrigeration unit that needs to meet this time-sensitive and increased cooling requirements. That is, the depressurization time will be set to allow just enough time to fill and pressurize accumulator 14 before accumulator 12 depletes its liquid CO2 supply. This arrangement between accumulators 12, 14 and the corresponding piping and valves is necessary to ensure a continuous and reliable supply of gaseous CO2 from outlet 95 for subsequent plant applications. However, as stated above, Figure 1 The known system 10 requires a large amount of power and energy to accommodate the interaction between the storage units 12 and 14 in order to provide a reliable source of gaseous CO2 at the system outlet 95.

[0011] A reciprocating process is provided when the first reservoir 12 is taken offline from the delivery service and is instead refilled using liquid CO2 from a large-capacity supply storage tank 16 or container containing liquid CO2.

[0012] The patterns of the bankers 12 and 14 in system 10 are shown in Table 1 below and are consistent with those in the system. Figure 1 Related.

[0013] Table 1

[0014]

[0015] Summary of the Invention

[0016] Compared to the known systems discussed above, embodiments of the present invention require a smaller condenser and refrigeration unit with a smaller footprint at the plant or facility. Therefore, in this embodiment, all CO2 emitted during depressurization of the accumulator is captured and recovered for subsequent use in the accumulator, thereby reducing the capital and operating costs associated with the refrigeration components of the system.

[0017] Therefore, this document provides a pressure-reducing system for generating high-pressure gas (such as CO2 gas) from a pair of accumulators. The system includes a gas buffer tank assembly comprising gas buffer tanks for the pair of accumulators. The gas buffer tank assembly also includes a pair of pressure-reducing valves for each accumulator, such that pressure reduction from the two accumulators to the gas buffer tank and from the gas buffer tank to the condenser benefits the overall system pressure reduction. This embodiment achieves pressure equalization between the gas buffer tank and the respective accumulators, thereby temporarily retaining that portion of the intermediate gas from each accumulator in the gas buffer tank before allowing it to condense and re-liquefy for reintroduction into the same accumulator.

[0018] In some embodiments herein, an apparatus is provided for depressurizing a pair of reservoirs to provide high-pressure gas, the apparatus comprising: a tank in fluid communication with each of the pair of reservoirs for receiving steam from the pair of reservoirs for storage and distributing the steam to a distant location other than the pair of reservoirs and the outside atmosphere; a first fluid connection including a first valve assembly interconnecting the tank and the first reservoir of the pair of reservoirs; and a second fluid connection including a second valve assembly interconnecting the tank and the second reservoir of the pair of reservoirs; wherein the first fluid connection of the first valve assembly and the second fluid connection of the second valve assembly are each configured and arranged to deliver steam from a corresponding one of the first and second reservoirs to the tank during alternating intervals.

[0019] In some embodiments of the device, a condenser for condensing vapor into liquid is included at a remote location.

[0020] In some embodiments, the device further includes a receiving tank fluidly connected to the condenser for receiving and storing liquid until it is needed by the first and second reservoirs.

[0021] In some other embodiments of the device, the steam comes from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen.

[0022] In some embodiments herein, a method is provided for depressurizing a pair of reservoirs to provide a high-pressure gas, the method comprising: (a) drawing a portion of vapor from a first reservoir of the pair of reservoirs into a tank; (b) equalizing the pressure in the first reservoir and the tank to temporarily contain a portion of the vapor from the first reservoir as an intermediate gas in the tank; (c) supplying the intermediate gas to a distant location other than the pair of reservoirs and the atmosphere; (d) condensing the intermediate gas into a liquid at the distant location; and (e) returning the liquid to the first reservoir.

[0023] In some embodiments, the method includes supplying high-pressure gas from a second reservoir of a pair of reservoirs during steps (a) to (e).

[0024] In some other embodiments, the method further includes storing the liquid at a remote location before returning the liquid to the first reservoir.

[0025] In some other embodiments, the method includes the steam originating from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen. Attached Figure Description

[0026] To gain a more complete understanding of the invention, reference can be made to the following description of exemplary embodiments considered in conjunction with the accompanying drawings, in which:

[0027] Figure 1 A schematic diagram of a known system for depressurizing gas to provide high-pressure CO2 is shown.

[0028] Figure 2 A schematic diagram of an embodiment of the pressure reduction system, apparatus and method of the present invention for high-pressure gas delivery, such as CO2 gas, is shown.

[0029] Figure 3 It shows in Figure 2 The gas buffer tank embodiment of the present invention used in the system embodiment shown is shown. Detailed Implementation

[0030] Before explaining the embodiments of the present invention in detail, it should be understood that the invention is not limited in its application to the details of the construction and arrangement of the components shown in the drawings (if any), as the invention can have other embodiments and can be practiced or implemented in different ways. Furthermore, it should be understood that the wording or terminology used herein is for illustrative purposes and not restrictive.

[0031] In the following description, terms such as horizontal, upright, vertical, above, below, and under are used only to clearly illustrate the purpose of the invention and should not be considered as limiting terms. The accompanying drawings (if any) are for illustrative purposes and are not intended to be drawn to scale.

[0032] The term "fluid connector" as used in this article can be considered as a conduit, pipe, channel, etc., that provides fluid transport or fluid communication, and also includes multiple such components.

[0033] refer to Figure 2 and Figure 3The embodiments of the invention described herein include a depressurization system 100, which, among other components, has a gas buffer tank assembly 102 (hereinafter also referred to as "buffer tank assembly 102"). The buffer tank assembly 102 can be retrofitted into a known system 10 or has the original configuration of a known system for interacting with accumulators 12, 14. The buffer tank assembly 102 collects a portion (if not all) of the CO2 gas generated from one of the respective accumulators 12, 14 during depressurization to equalize the pressure between them, thereby temporarily storing the CO2 vapor and dividing the depressurization phase into two separate phases. The buffer tank assembly 102 includes, as described above... Figures 2 to 3 The gas buffer tank 104 is shown. That is, with respect to the reservoir 12, the buffer tank assembly 102 includes the gas buffer tank 104, the fluid connection 106 or pipe and the valve 108; and with respect to the reservoir 14, the buffer tank assembly 102 includes the gas buffer tank 104, the fluid connection 206 or pipe and the valve 208.

[0034] Example 100 of the pressure reduction system is a high-pressure gas delivery system, and it is related to... Figure 1 The difference between the known system 10 and the known system 100 is the addition of a gas buffer tank 104 and its corresponding piping and valves (valve assemblies) to or from each of the reservoirs 12, 14. System 100 is constructed and arranged to maintain a continuous supply of high-pressure gaseous CO2, wherein the operating cycle of the buffer tank assembly 102 is configured to replenish the first reservoir in the reservoirs 12, 14, while the second reservoir in the reservoir distributes the gaseous CO2 product. In this construction and operation, there is no lag, pause, or downtime during on-demand CO2 supply, and the condenser and refrigeration unit footprint required for depressurization of the reservoirs 12, 14 is much smaller than that required by the known system 10. Table 2 below provides examples of operating cycles and corresponding "modes".

[0035] The high-pressure gas delivery system is generally shown as 100. A first reservoir 12 delivers high-pressure gaseous CO2 to an outlet 95 for use in gaseous applications via fluid connections 28, 32 or pipes, while a second reservoir 14 is refilled from a large-capacity liquid CO2 supply section 16. The second reservoir 14 must be refilled and ready for resumption of operation before the first reservoir 12 depletes its CO2. Before the reservoir 14 can be refilled with liquid CO2, it must first be depressurized. The depressurization of the reservoir 14 is carried out in two stages: Stage 1—The reservoir 14 is first depressurized to the gas buffer tank 104 of the buffer tank assembly 102 until the corresponding pressures in the reservoir 14 and the gas buffer tank 104 are equalized, temporarily storing a portion of the CO2 vapor in the gas buffer tank 104; Stage 2—The reservoir 14 is then fully depressurized to the receiver 26 via fluid connections 39, 44 leading to the condenser 24, whereby the CO2 vapor condenses into a liquid. This condensation is achieved via an external refrigeration unit (not shown), and the condensed liquid is supplied to receiver 26 via fluid connection 45 from condenser 24 to receiver. Once accumulator 14 is fully depressurized to the desired pressure setpoint, liquid CO2 temporarily stored in receiver 26 is returned to accumulator 14 via fluid connections 46, 42 by opening valve 57. Accumulator 14 is also refilled or filled to the desired level setpoint with additional liquid from liquid CO2 supply unit 16, with a feed stream 18 containing liquid CO2 introduced into accumulator 14 via fluid connection 22. Accumulator 14 is heated (e.g., by electric heater 50) to evaporate the liquid CO2 stored in accumulator and pressurize it to the delivery pressure so that system 100 generates a gaseous CO2 stream, which is then delivered to outlet 95 via fluid connections 30, 32 for application use. The delivery pressure at outlet 95 is in the range of 600 psig to 1000 psig.

[0036] When reservoir 14 is refilled and pressurized, gas buffer tank 104 is depressurized and transferred to receiver 26 via fluid connections 206, 39, 44, 45, where CO2 vapor is condensed into liquid by a heat exchanger in condenser 24. This condensation is achieved by an external refrigeration unit (not shown, but mentioned) connected to the heat exchanger of condenser 24. The liquid CO2 is also temporarily held in receiver 26 until the next cycle, whereby the liquid CO2 will be transferred to reservoir 12 via fluid connections 46, 40 or pipes after the reservoir has undergone its depressurization phase.

[0037] By equalizing the pressure between accumulator 14 and gas buffer tank 104 before fully depressurizing accumulator 14, the amount of CO2 vapor condensed in condenser 24 during this phase is significantly less than that occurring in known system 10. By temporarily containing a portion of the CO2 vapor in gas buffer tank 104, the CO2 vapor condensation process can be extended over a longer timeframe, thereby reducing the cooling requirements of condenser 24; rather than being limited to the strict amount of time allocated for depressurizing accumulator 14 as required in known system 10. During the filling and pressurization phases of accumulator 14, gas buffer tank 104 is depressurized and the corresponding CO2 vapor is condensed. This, in turn, allows the refrigeration unit to operate continuously or nearly continuously to avoid frequent cycling.

[0038] The patterns in system embodiment 100 regarding savings devices 12 and 14 are shown in Table 2 below, and are consistent with those in the following table. Figures 2 to 3 Related.

[0039] Table 2

[0040]

[0041]

[0042] Due to the reduced size of the refrigeration unit and condenser 24, system 100 is therefore more economical than the known system 10.

[0043] The depressurization cycle phases of the reservoirs 12 and 14 of the buffer tank assembly 102 and the gas buffer tank 104, and their interactions, can be summarized as follows:

[0044] 1. To equalize the pressure of the corresponding storage devices 12, 14 and gas buffer tank 104.

[0045] 2. Depressurize / reliquefy CO2 in the reservoir to fill receiver 26.

[0046] 3. Fill the savings device from the receiver.

[0047] 4. Fill the reservoir from the liquid CO2 feed 16 and begin depressurizing / reliquefying the gas buffer tank 104 to fill the receiver 26.

[0048] 5. Pressurize the accumulator using the corresponding heaters 48 and 50.

[0049] 6. Gas buffer tank 104 is fully depressurized (receiver 26 is now partially filled with liquid CO2) and put into standby mode.

[0050] 7. When the second reservoir is depleted, switch to distributing high-pressure CO2 from the first reservoir.

[0051] 8. Begin the decompression cycle in the second reservoir.

[0052] 9. Repeat.

[0053] Gas buffer tank 104 reduces the amount of CO2 gas leaving the accumulators 12 and 14 during depressurization and provides more time for the CO2 gas to be reliquefied via condenser 24 and refrigeration unit. Due to the added time from gas buffer tank 104, the size and associated footprint of condenser 24-refrigeration unit are significantly reduced, and therefore the associated capital and operating costs of system 100 are also reduced. This embodiment provides a cost-effective solution for capturing all CO2 gas during depressurization to (i) avoid loss of CO2 products, (ii) avoid increase in GHG emissions, and (iii) reduce the size of the condenser / refrigeration unit used to condense CO2 vapor.

[0054] Manual valves 71 to 93 (odd numbers) are provided for closing and partially closing corresponding fluid connections or pipes to regulate the timing of the delivery of steam and liquid through the corresponding systems 10, 100, and may include one or more manual valves depending on the system application.

[0055] This embodiment can be applied to other liquid products (e.g., liquid nitrogen or LIN) using the same equipment and processes described herein, where the liquid is heated inside a reservoir or container to deliver a high-pressure gas and to recover and use any gas or vapor that would otherwise be discharged in a cost-effective manner.

[0056] Even without the addition of a condenser 24 with its heat exchanger and a refrigeration unit, the gas buffer tank 104 will significantly reduce the amount of gas discharged during depressurization.

[0057] It should be understood that the embodiments described herein are merely exemplary, and those skilled in the art can make changes and modifications without departing from the spirit and scope of the invention. All such changes and modifications are intended to be included within the scope of the invention as provided in the appended claims. It should be understood that the above embodiments are not only alternatives but can also be combined.

Claims

1. An apparatus for depressurizing a pair of accumulators to provide high-pressure gas, the apparatus comprising: A gas buffer tank in fluid communication with each of the pair of reservoirs is used to receive steam from the pair of reservoirs for storage and to distribute the steam to a condenser other than the pair of reservoirs and the outside atmosphere for condensing the steam into liquid. A first fluid connection, the first fluid connection including a first valve assembly interconnecting the gas buffer tank and a first reservoir of the pair of reservoirs; A second fluid connection, the second fluid connection including a second valve assembly interconnecting the gas buffer tank and a second reservoir of the pair of reservoirs; A receiving tank, which is fluidly connected to the condenser, is used to receive and store the liquid until it is needed by the first and second reservoirs; The first fluid connection of the first valve assembly and the second fluid connection of the second valve assembly are each configured and arranged to deliver the steam from a corresponding one of the first and second reservoirs to the gas buffer tank during alternating intervals.

2. The apparatus of claim 1, wherein, The vapor comes from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen.

3. A method for depressurizing a pair of accumulators to provide high-pressure gas, the method comprising: (a) A portion of the steam is drawn from the first of the pair of reservoirs into the gas buffer tank; (b) Equalize the pressure in the first reservoir and the gas buffer tank to temporarily contain the vapor portion from the first reservoir as an intermediate gas in the gas buffer tank; (c) The intermediate gas is supplied to a condenser other than the pair of reservoirs and the atmosphere; (d) The intermediate gas is condensed into a liquid at the condenser; (e) Provide a receiving tank, which is fluidly connected to the condenser, for receiving and storing the liquid until it is needed by the first reservoir; as well as (f) Return the liquid to the first reservoir.

4. The method of claim 3, further comprising supplying high-pressure gas from the second reservoir of the pair of reservoirs during steps (a) to (f) of claim 3.

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

6. The method of claim 3, wherein, The vapor comes from a liquid selected from the group consisting of liquid CO2 and liquid nitrogen.

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