Seal gas leak recovery and seal gas boost system and method

Abstract

The present invention discloses a compressor unit (1) comprising a main compressor (3) having an intake side (3S), a delivery side (3D), and at least one dry gas seal (7). The dry gas seal (7) is fluidly connected to a sealing gas feed circuit (9), which is adapted to receive sealing gas from the delivery side (3D) of the main compressor (3) and feed the sealing gas to at least one dry gas seal (7). An auxiliary compressor unit (25) is also provided, which includes a sealing gas inlet (29) and a sealing gas outlet (27), the sealing gas inlet being fluidly connected to the sealing gas feed circuit (9), the sealing gas outlet being fluidly connected to the sealing gas feed circuit (9), and being adapted to increase the sealing gas pressure in the sealing gas feed circuit (9). The auxiliary compressor unit (25) is also adapted to receive a gas flow, such as main exhaust gas from the dry gas seal (7), from the main compressor (3) for recovery purposes.

Description

Technical Field

[0001] The subject matter disclosed herein relates to gas compressor devices including dry gas seals, and to methods of operating such devices. Background Technology

[0002] Fossil fuels remain the primary energy source for producing thermoelectricity needed in some industrial processes, including power generation. Attempts have been made to reduce the environmental impact of this energy source. The cleanest fossil fuel is natural gas, which is primarily composed of methane, because the combustion of methane produces more heat than any other hydrocarbon, thus providing greater environmental benefits due to a significant reduction in carbon dioxide and other pollutants that impact the environment.

[0003] However, the extraction and transportation of natural gas releases unburned gases into the atmosphere, primarily methane. This has serious environmental implications, as methane contributes to climate change, particularly the greenhouse effect. In fact, like carbon dioxide, methane absorbs heat from the atmosphere. Over a 100-year period, methane's global warming potential (GWP) is approximately 28 times that of carbon dioxide; GWP is a measure of how much heat a greenhouse gas captures in the atmosphere over a specific time period.

[0004] Therefore, efforts have been made throughout the entire process of natural gas extraction, transportation, and use to reduce the amount of natural gas released into the atmosphere.

[0005] The rotary seal of the gas compressor plays a primary role in this method. Dry gas seals have become increasingly popular non-contact seals to effectively reduce process gas leakage from centrifugal compressors or other turbines (Stahley, John S., “Dry Gas Seals Handbook”, copyright 2005, PennWell, ISBN 1-59370-062-8). Dry gas seals use a process gas flow to provide an effective non-contact seal between the rotating shaft and the static seal. Dry gas seals require a clean, dry gas flow to operate. Typically, the same gas processed by the compressor is used as the sealing gas. The sealing gas is taken from the delivery side of the compressor, and the compressor should be operable to provide adequately pressurized sealing gas.

[0006] In compressors used to process natural gas, such as in gas pipelines, natural gas leaking from dry gas seals is typically burned in a flare to avoid releasing the gas into the atmosphere, but this still produces greenhouse gases (carbon dioxide) and destroys a large amount of valuable raw materials.

[0007] Therefore, it is recommended to recover gas leaking from dry gas seals. A circuit for hydrocarbon recovery in centrifugal compressor systems using dry gas seals is disclosed in the paper "Turbomachinery Hydrocarbon Loss recovery systems" by Sergio Cipriani et al., presented at the Energy Network Gas Turbine Symposium in Banff, Alberta, Canada in October 2019.

[0008] While dry gas seals are particularly effective at providing a reliable seal for rotating machinery, they require a complex support system, which negatively impacts the cost of compressor units using such seals. Among other functions, the support system must also provide pressurized sealing gas when the compressor is stopped or started, i.e., when the compressor itself cannot provide sufficient pressurized sealing gas.

[0009] As mentioned above, special measures are required to reduce the release of process gases into the atmosphere, which increases the complexity of the support system.

[0010] Compressors, such as centrifugal compressors in gas pipelines, require maintenance and other interventions. Before turning on a compressor for maintenance or other purposes, the process gases it contains must be removed. Gases contained in the compressor after shutdown are typically released into the atmosphere before being turned on again. This represents a loss of hydrocarbons and also has a negative impact on the environment.

[0011] Therefore, it is advantageous to simplify the dry gas seal support system while maintaining seal efficiency and reducing the release of pollutants into the atmosphere. Summary of the Invention

[0012] According to one aspect, a compressor assembly is disclosed, comprising a main compressor having an intake side, a delivery side, and at least one dry gas seal. The main compressor further includes a sealing gas feed circuit adapted to receive sealing gas from the delivery side of the main compressor and feed the sealing gas to the dry gas seal.

[0013] In the embodiments disclosed herein, the compressor unit further includes an auxiliary compressor unit comprising a sealing gas inlet and a sealing gas outlet fluidly connected to the sealing gas feed circuit. When the gas pressure at the delivery side of the main compressor is insufficient or unavailable, such as during main compressor shutdown or during start-up and shutdown transients, the auxiliary compressor unit is adapted to perform a sealing gas pressurization function.

[0014] The auxiliary compressor unit is adapted to receive sealing gas from the sealing gas feed circuit through the sealing gas inlet at the sealing gas inlet pressure, and to return the sealing gas to the sealing gas feed circuit at the sealing gas outlet pressure, which is higher than the sealing gas inlet pressure.

[0015] In the embodiments disclosed herein, the auxiliary compressor unit is also adapted to receive and process the gas stream from the main compressor. The gas stream may include sealing gas discharged from the dry gas seal of the main compressor. The auxiliary compressor unit is thus configured to recover the discharged sealing gas, thereby preventing the discharged sealing gas from being released into the environment or burned in a flare.

[0016] Additional piping suitable for receiving gas flow from the main compressor may be provided. In some embodiments, in addition to or in lieu of the sealing gas discharged from the dry gas seal, the gas flow from the main compressor may include process gas removed from the main compressor after it has been shut down, to allow the main compressor to be turned on without releasing process gas into the environment.

[0017] Other advantageous features and implementation schemes of the compressor unit, as well as related operating methods, are summarized below. Attached Figure Description

[0018] Now, please briefly refer to the attached diagram, in which:

[0019] Figure 1 A schematic diagram of a compressor device according to this disclosure is shown;

[0020] Figure 2 A diagram of an auxiliary compressor unit in one embodiment is shown;

[0021] Figure 3 A diagram of an auxiliary compressor unit in another embodiment is shown;

[0022] Figure 4 A diagram of an auxiliary compressor unit in another embodiment is shown; and

[0023] Figure 5 and Figure 6 A flowchart of a method for operating a compressor device according to the present disclosure is shown. Detailed Implementation

[0024] According to the embodiments disclosed herein, the compressor unit includes at least one main compressor having one or more dry gas seals. Gas processed by the main compressor is used as the sealing gas for the dry gas seals. The sealing gas is fed to each dry gas seal via a sealing gas feed circuit. A sealing gas exhaust recovery system is fluidly connected to the main exhaust gas of the dry gas seal. The sealing gas recovery system includes an auxiliary compressor designed to pressurize sealing gas leaking from the dry gas seal from a lower pressure to a pressure suitable for injecting the recovered sealing gas into the sealing gas feed circuit or into the suction side of the main compressor.

[0025] The auxiliary compressor is also used to increase the pressure of the sealing gas in the sealing gas feed circuit when the main compressor is off, and during shutdown or start-up transients. This prevents the dry gas seal from fouling during compressor shutdown and transients when there is no gas pressure or insufficient gas pressure is available on the main compressor delivery side. By using the same auxiliary compressor to recover the main exhaust gas from the dry gas seal and to increase the pressure of the sealing gas during compressor shutdown or restart / shutdown transients, the complexity of the compressor unit, and especially the complexity of the support system for the dry gas seal, is significantly reduced.

[0026] According to other embodiments disclosed herein, the compressor unit includes at least one main compressor having one or more dry gas seals. The gas processed by the main compressor is used as the sealing gas for the dry gas seals. The sealing gas is fed to each dry gas seal via a sealing gas feed circuit. An auxiliary compressor is provided to increase the pressure in the sealing gas feed circuit when the main compressor is shut down or during start-up / shutdown transients, when the pressure on the main compressor delivery side is insufficient or unavailable. This also prevents fouling of the dry gas seals during main compressor shutdowns and transients. The same auxiliary compressor is also adapted to remove process gas from the main compressor after it is shut down and before it is turned on, for example, for maintenance purposes. By using the same auxiliary compressor to increase the sealing gas pressure during compressor shutdowns or restart / shutdown transients and to discharge process gas from the main compressor when it is shut down, the complexity of the compressor unit, and particularly the complexity of the support system for the dry gas seals, is significantly reduced.

[0027] Now refer to the attached diagram, Figure 1 A schematic diagram of a compressor device 1 according to one embodiment is shown. Figure 2 It shows Figure 1 An enlarged view of the sealed gas exhaust recovery system.

[0028] The compressor unit 1 includes a main compressor 3 having an intake side 3S and a delivery side 3D. The main compressor 3 may be part of a compressor assembly (not shown) including one or more compressors along a common axis. Drives include electric motors, gas turbine engines, steam turbines, etc. (in...) Figure 1(Schematally shown in the diagram) Drives the main compressor 3 to rotate. The main compressor 3 is fluidly connected to a piping system 5, which includes an inlet pipe 5A and an outlet pipe 5B. Process gas at a first low pressure is fed to the suction side 3S of the main compressor 3 through the inlet pipe 5A. Process gas at a second higher pressure is delivered to the outlet pipe 5B of the piping system 5 through the delivery side 3D of the main compressor 3. Isolation valves 5C and 5D may be arranged along the inlet pipe 5A and the outlet pipe 5B, respectively. Isolation valves 5C and 5D may be closed to isolate the main compressor 3 from the piping system 5, for example, for maintenance, repair, or replacement purposes.

[0029] exist Figure 1 In one embodiment, the main compressor 3 is an intermediate bearing centrifugal compressor having one or more impellers 4 and two sealing devices 6, one located at the drive end of the main compressor 3 and one located at the non-drive end of the main compressor 3. In other embodiments not shown, for example when the main compressor has a cantilever configuration, the main compressor may have only one sealing device 6. Figure 1 In the schematic representation, each sealing device 6 includes a dry gas seal 7, an inner labyrinth seal 8, and an outer barrier seal 10 arranged between the dry gas seal 7 and the corresponding bearing (not shown).

[0030] The dry gas seal 7 is fluidly connected to the sealing gas feed circuit 9, which is adapted to receive process gas from the piping system 5 and treat the process gas as sealing gas before feeding it to the dry gas seal 7. Before being delivered to the dry gas seal 7, the process gas is appropriately filtered and heated. A filter is schematically shown at 11, and a heater is schematically shown at 13. Filter 11 and heater 13 are designed to remove contaminants from the process gas and to maintain the temperature of the sealing gas above the dew point to prevent moisture condensation. The positions of filter 11 and heater 13 along the sealing gas feed circuit 9 can be reversed.

[0031] exist Figure 1 In one embodiment, as an example, filter 11 includes two filter components 11A and 11B connected in parallel in a duplex configuration. A pressure control valve 15 is arranged between heater 13 and dry gas seal 7, with orifices 17A and 17B downstream of pressure control valve 15 to balance the sealing airflow toward the two dry gas seals 7. The above configuration is merely an example, and those skilled in the art will understand that different configurations are possible. For example, heater 13 may be omitted. Furthermore, the order of the filter and heater may be different. Orifices 17A and 17B and valve 15 may be replaced by two valves connected in parallel.

[0032] The sealing gas feed circuit 9 is fluidly connected to the piping system 5 located downstream of the main compressor 3, that is, connected to the outlet pipe 5B, so that the process gas under the delivery pressure of the main compressor 3 enters the sealing gas feed circuit 9.

[0033] A portion of the sealing gas supplied to the dry gas seal 7 leaks through the main exhaust and auxiliary exhaust at approximately ambient pressure, for example, between 1 barA and 1.5 barA. As used in the art, the unit of measurement, barA, represents absolute pressure measured in bars. To prevent the discharged sealing gas from entering the environment, the compressor unit 1 includes a sealing gas exhaust recovery system 21, which is adapted to recover at least the main exhaust from the dry gas seal 7 via the main exhaust recovery conduit 14. Figure 1 The sealing gas exhaust recovery system 21 shown schematically includes an accumulation chamber 23 fluidly connected to the dry gas seal 7 to collect sealing gas discharged from the dry gas seal. The accumulation chamber 23 may be adapted to collect further leakage from other components of the compressor unit 1 (such as valve actuator exhaust ports, gas turbine fuel gas preheating exhaust ports, pneumatic gas turbine starter exhaust ports, etc. (not shown)) or to seal exhaust from the rod packing ring of the reciprocating compressor rod (to be described).

[0034] Although the accumulation chamber 23 is shown as a dedicated component in the embodiment shown in the accompanying drawings, it should be noted that the flow rate involved is so small that the accumulation chamber 23 may also consist of the inner cavity of one or more connecting pipes or tubes.

[0035] The sealing gas exhaust recovery system 21 also includes an auxiliary compressor unit, schematically shown at 25, which is fluidly connected to the accumulation chamber 23 via a first gas inlet 24 and is also fluidly connected to the sealing gas feed circuit 9 in a manner to be described, and optionally connected to the suction side 3S of the main compressor 3. Figure 2 A more detailed representation of the sealing gas exhaust recovery system 21 and the auxiliary compressor unit 25 is shown in the figure.

[0036] The auxiliary compressor unit 25 includes an auxiliary compressor 26. The auxiliary compressor 26 may include a reciprocating compressor. The auxiliary compressor 26 may include multiple stages and multiple cylinders.

[0037] In some implementations, the accumulation chamber 23 may be embedded within the auxiliary compressor 26, that is, it may be part of the auxiliary compressor.

[0038] exist Figure 1 and Figure 2 In the schematic diagram, the reciprocating compressor 26 is a dual-cylinder reciprocating compressor including a first cylinder 26A and a second cylinder 26B. Each cylinder includes a piston that reciprocates within the cylinder.

[0039] The reciprocating compressor 26 is a double-acting reciprocating compressor in which each cylinder is divided into two compression chambers by a corresponding piston, in which process gas is alternately drawn in, compressed, and discharged. As can be seen from the description below, the two chambers of each cylinder can be arranged in series or in parallel and can form part of the same compressor stage, or can belong to two different compressor stages that are usually arranged in series.

[0040] During normal operation of the main compressor 3, the pressurized gas flow from the delivery side 3D of the main compressor 3 enters the sealing gas feed circuit 9 and is treated (filtered and heated) before being fed as sealing gas to the dry gas seal 7 of the main compressor 3. Most of the sealing gas delivered to the dry gas seal 7 flows through the labyrinth seal 8 in the main compressor 3 and is treated together with the mainstream of process gas entering the suction side 3S of the main compressor 3. A portion of the sealing gas (typically between about 5% and about 10%) leaks from the dry gas seal 7 and is collected in the accumulation chamber 23 at near ambient pressure (typically between about 1 barA and about 2 barA). The leaked sealing gas (main exhaust) is recovered from the accumulation chamber and pressurized by the auxiliary compressor unit 25, and returned to the sealing gas feed circuit 9 and / or to the suction side 3S of the main compressor 3. The pressure values ​​described above are exemplary and should not be considered as limiting the scope of this disclosure. Lower or higher pressure values ​​are possible, for example, about 4.5 barA.

[0041] More specifically, as will be described in more detail below, the auxiliary compressor unit 25 is adapted to pressurize the sealing gas leaking from the dry gas seal 7 and collected in the accumulation chamber 23 from near ambient pressure to a pressure suitable for feeding the recovered sealing gas into the sealing gas feed circuit or into the suction side 3S of the main compressor 3, i.e., to a pressure substantially higher than the pressure inside the accumulation chamber 23.

[0042] Low-pressure sealing gas enters the auxiliary compressor unit 25 from the accumulation chamber 23 through the first gas inlet 24 and returns to the sealing gas feed circuit 9 via outlet line 27 or 27X. Reference numeral 27A indicates the connection point between the sealing gas feed circuit 9 and outlet line 27 (or 27X). Alternatively or in combination, the recovered sealing gas discharged from the dry gas seal 7 can be returned to the inlet line 5A of the piping system 5 via connecting line 30. In some embodiments, valve system 34 may be associated with lines 27 and 30 to selectively redirect the recovered sealing gas to the piping system 5 via connecting line 30 or to the sealing gas feed circuit 9 via outlet line 27. Figure 1 and Figure 2 In the middle, valve system 34 includes a three-way valve.

[0043] The auxiliary compressor unit 25 is also fluidly connected to the sealing gas feed circuit 9 via a second gas inlet 29 for the purposes described below.

[0044] When the main compressor 3 is shut down or during a shutdown or restart transient, there is no pressurized process airflow at the delivery side 3D of the main compressor 3, and the sealing gas can be obtained from this delivery side. However, in order to prevent fouling of the dry gas seal 7 and possible damage to it when the main compressor 3 is restarted, the sealing airflow must also be maintained during the shutdown of the main compressor 3 or during a shutdown or restart transient.

[0045] To provide a continuous sealing gas flow, the auxiliary compressor unit 25 is fluidly connected to the sealing gas feed circuit 9 via the aforementioned second gas inlet 29. Process gas is extracted from the piping system 5 located downstream of the main compressor 3 via the sealing gas feed circuit 9, fed to the auxiliary compressor unit 25 via the second gas inlet 29, and then delivered back to the sealing gas feed circuit 9 at a higher pressure via the outlet line 27 (or 27X), and delivered to the dry gas seal 7.

[0046] Therefore, the same auxiliary compressor unit 25 provides a dual function: recovering the sealing gas leaking from the dry gas seal 7 (main exhaust); and increasing the pressure of the sealing gas during shutdown of the main compressor 3 and / or during shutdown and restart transients, thereby providing a continuous sealing gas flow to the dry gas seal 7.

[0047] Figure 2 The configuration of the auxiliary compressor unit 25 and more details of the fluid connection between the auxiliary compressor unit 25 and the sealing gas feed circuit 9 are shown.

[0048] The first cylinder 26A of the auxiliary reciprocating compressor 26 includes a first piston 26C that reciprocates within the cylinder 26A. The second cylinder 26B includes a second piston 26E that reciprocates within the cylinder 26B. A single crankshaft, rotatably supported in a crankcase (not shown), drives the two pistons 26C and 26E to a drive, such as, for example, an electric motor (not shown).

[0049] The first piston 26C divides the first cylinder 26A into a first compression chamber 32A and a second compression chamber 32B. The second piston 26E divides the second cylinder 26B into a third compression chamber 32C and a fourth compression chamber 32D. The suction and delivery sides of each chamber 32A, 32B, 32C, 32D are indicated by the same reference numerals for the chamber, followed by the letter "S" for the suction side and the letter "D" for the delivery side. Thus, for example, reference numerals 32CS and 32CD indicate the suction and delivery sides of chamber 32C. Chambers 32A, 32B, and 32C are arranged in series and represent three stages of the reciprocating compressor 26, which is adapted to compress the recovered sealing gas discharged from the dry gas seal 7. The fourth chamber 32D is used to increase the sealing gas pressure during the stop or start-up and shutdown transients of the main compressor 3, as will be described in more detail later.

[0050] The accumulation chamber 23 is fluidly connected to the suction side 32AS of the first chamber 32A of the first cylinder 26A via the first gas inlet 24. The delivery side 32AD of the first chamber 32A is fluidly connected to the suction side 32BS of the second chamber 32B. An intercooler 43 may be arranged along a pipeline 41 that fluidly connects the delivery side 32AD of chamber 32A and the suction side 32BS of chamber 32B to each other. The delivery side 32BD of the second chamber 32B is fluidly connected to the suction side 32CS of the third chamber 32C via a delivery pipe 45, along which another intercooler 47 may be arranged.

[0051] exist Figure 2 In the implementation scheme, the suction side 32DS of the fourth chamber 32D is fluidly connected to the second gas inlet 29 of the auxiliary compressor unit 25.

[0052] As can be seen from the following description of the operation of the auxiliary compressor unit 25, the first chamber 32A, the second chamber 32B and the third chamber 32C constitute an auxiliary compressor section suitable for pressurizing the sealing gas discharged from the accumulation chamber 23, while the fourth chamber 32D constitutes an auxiliary compressor section suitable for increasing the pressure of the sealing gas when the main compressor 3 is shut down or during the start-up or shutdown transients of the main compressor.

[0053] like Figure 2 As shown, the delivery side 32CD of the third chamber 32C is fluidly connected to the outlet line 27 via a delivery conduit 48, and thus fluidly connected to the sealing gas feed circuit 9. In an embodiment, when a fluid connection is provided between the auxiliary compressor unit 25 and the suction side 3S of the main compressor 3 (e.g., via line 30), the delivery conduit 48 may be fluidly connected to the suction side 3S of the main compressor 3, rather than to the sealing gas feed circuit 9 via the valve system 34 as described above.

[0054] In the implementation plan, such as Figure 2As shown, a return line 49, including a pressure control valve 51, fluidly connects the delivery side 32CD of the third chamber 32C to the accumulation chamber 23, such that if the output flow rate of the auxiliary compressor unit 25 is higher than the sealing gas required for the dry gas seal via the sealing gas feed circuit 9, the sealing gas pressurized by the auxiliary compressor unit 25 can be returned to the accumulation chamber 23. A cooler 53 can be positioned along the return line 49 to prevent the gas collected in the accumulation chamber 23 from overheating.

[0055] The delivery side 32DD of the fourth chamber 32D is connected to the outlet line 27 via a pipe 55, so that the sealing gas processed through the fourth chamber 32D can be fed to the dry gas seal 7, as described in detail later.

[0056] In some embodiments, the circulation line 57 may be arranged counter-parallel to the fourth chamber 32D, such that the gas treated in the fourth chamber 32D can circulate in a closed loop if no flow from the fourth chamber 32D to the outlet line 27 is required. A circulation valve 59 is provided along the circulation line 57. The circulation valve 59 selectively opens and closes the circulation line 57 as needed and according to operating conditions. Additionally, a cooler 61 may be provided along the circulation line 57 to cool the fluid circulating therein, thereby preventing overheating. Another valve 60 may be located between the conduit 55 and the outlet line 27. Using this arrangement, the gas in chamber 32D can be selectively treated and delivered to the outlet line 27 (circulation valve 59 closed and valve 60 open), or recirculated within the circulation line 57 (by closing valve 60 and opening circulation valve 59).

[0057] Although Figure 1 and Figure 2 A two-cylinder reciprocating compressor 26 is shown, but different numbers of reciprocating compressor cylinders and associated stages can be provided, such as one, three or more cylinders, with or without intercooling. Typically, at least one reciprocating compressor stage is used to process the sealing gas from the main exhaust of the dry gas seal 7, as well as to increase the pressure of the sealing gas in the sealing gas feed circuit 9.

[0058] The various operating conditions of the aforementioned sealed gas exhaust recovery system 21 will be discussed in detail below. The values ​​of the various parameters (such as pressure, temperature, and flow rate) mentioned below are provided to better understand the function of the compressor unit, are merely examples, and should not be construed as limiting this disclosure.

[0059] As described above, sealing gas should continue to be supplied to the dry gas seal 7 even when the main compressor 3 is not operating to prevent contamination and avoid serious damage to the dry gas seal 7 during main compressor startup. Since the shaft of the main compressor 3 is stationary and therefore the dry gas seal 7 does not rotate, the sealing gas flow rate during shutdown is typically lower than the flow rate during full operation. Because no pressurized process gas is available when the main compressor 3 is shut down, the sealing gas exhaust recovery system 21 is used to increase the pressure of the sealing gas supplied to the dry gas seal 7 by the sealing gas feed circuit 9.

[0060] More specifically, one or more of the compression chambers 32A to 32D are used to pressurize the sealing gas discharged from the dry gas seal 7 and to return the discharged sealing gas to the sealing gas feed circuit 9 or to the suction side 3S of the main compressor 3. At the same time, one or more of the compression chambers 32A to 32D are used to increase the pressure of the sealing gas in the sealing gas feed circuit 9.

[0061] exist Figure 2 In an exemplary embodiment, one of the two compression chambers 32A and 32B of the first compressor cylinder 26A and one of the two compression chambers 32C and 32D of the second compressor cylinder 26B (chamber 32C) is used to recover sealing gas from the main exhaust of the dry gas seal 7 and return the discharged sealing gas to the sealing gas feed circuit 9 at a suitable pressure. Simultaneously, the compression chamber 32D of the second compressor cylinder 26B is used to increase the sealing gas pressure from the sealing gas feed circuit 9.

[0062] In practice, during the shutdown of the main compressor 3, the auxiliary compressor unit 25 receives sealing gas discharged from the dry gas seal 7 from the accumulation chamber 23 at near ambient pressure (e.g., between about 1 barA and about 1.5 barA), and further receives additional sealing gas flow from the second gas inlet 29 at a higher pressure. The two sealing gas flows are pressurized at substantially the same pressure and returned to the sealing gas feed circuit 9 at a pressure suitable for delivery to the dry gas seal 7.

[0063] In some implementations, and as a non-limiting example, approximately 10m 3 A sealing gas flow rate of [value] h can be delivered from the second gas inlet 29 to the fourth compression chamber 32D of the auxiliary reciprocating compressor 26. The pressure is increased to approximately 52 barA, and the gas returns to the sealing gas feed circuit 9 via the outlet line 27, and from there is delivered to the dry gas seal 7. In this way, the auxiliary compressor unit 25 acts as a sealing gas booster during the shutdown of the main compressor 3. The temperature and pressure of the gas delivered to the compression chamber 32D of the auxiliary compressor unit 25 through the second gas inlet 29 depend on the shutdown stabilization conditions in the main compressor 3. For example, the temperature can be approximately 45°C and the pressure (shutdown stabilization pressure) can be approximately 47.2 barA.

[0064] Meanwhile, for example, at approximately 1.3 bar A, approximately 0.36 Sm 3 A small flow rate of / h is recovered from the main exhaust gas of the dry gas seal 7 and delivered to the accumulation chamber 23 at approximately ambient temperature.

[0065] It should be understood that the pressure and flow values ​​mentioned above, as well as any parameter values ​​mentioned herein, are merely exemplary and can even vary consistently, for example, by an order of magnitude, depending on the configuration of the compressor unit.

[0066] During the startup of the main compressor 3, the auxiliary compressor unit 25 continues to recover and pressurize the dry gas recovered through the main exhaust recovery pipe 14 to seal the main exhaust, and is further used to increase the pressure of the sealing gas in the sealing gas feed circuit 9 until the gas pressure at the delivery side 3D of the main compressor 3 is high enough to supply sealing gas to the sealing gas feed circuit 9 at the appropriate pressure, without further pressurization via the auxiliary compressor unit 25. Figure 2 In an exemplary embodiment, the sealing gas pressurization function is again performed by the fourth compression chamber 32D of the auxiliary reciprocating compressor 26, while the remaining compression chambers 32A, 32B and 32C process the waste sealing gas from the main exhaust recovery duct 14.

[0067] Under these operating conditions, the sealing gas pressure in outlet pipeline 27 is approximately 10 m³ / s. 3 The flow rate can be approximately 52 barA at a flow rate of approximately 47 barA. The temperature of the process gas from the second gas inlet 29 can be approximately 23.5°C at a pressure of approximately 47 barA. Because the main compressor shaft and dry gas seal 7 rotate at increasingly higher speeds during this step, the main exhaust flow rate, for example, increases from approximately 2.352 m³ / h. 3 / h increased to approximately 3.36Sm 3 / h, and can have a pressure between about 1.3 barA and about 1.5 barA.

[0068] Under rated operating conditions (main compressor 3 at normal operating speed), the delivery pressure at the delivery side 3D of the main compressor 3 can be approximately 64 barA. There is no longer a need to increase the pressure of the sealing gas via the auxiliary compressor unit 25, resulting in a flow rate of approximately 0 m³ / s through the second gas inlet 29. 3 / h. Waste gas from the main exhaust recovery duct 14, with a pressure range between approximately 1.3 barA and 1.5 barA, will be recovered via the accumulation chamber 23 and the auxiliary compressor unit 25. For example, the main exhaust flow rate can range from approximately 2.352 m at approximately 1.3 barA. 3 / h to approximately 1.5 bar A at approximately 3.36 Sm 3 / h.

[0069] Since the sealing gas pressurization function of the compression chamber 32D is not required when the main compressor 3 is under rated operating conditions, the recirculation valve 59, which remains closed during shutdown or startup, will open to allow the gas contained in the fourth compression chamber 32D to be fully recirculated through the recirculation line 57. Valve 60 prevents gas delivered from the compression chamber 32D from entering the outlet line 27. Cooler 61 prevents the recirculated gas from overheating.

[0070] To automatically operate the auxiliary compressor unit 25 as a sealing gas booster during shutdown of the main compressor 3 or during start-up or shutdown transients, valve 65 (see...) Figure 1 The valve 65 can be arranged in the sealing gas feed circuit 9, located between the connection point 29A of the second gas inlet 29 to the sealing gas feed circuit 9 and the connection point 27A of the outlet line 27 to the sealing gas feed circuit 9. For example, the valve 65 can be a controlled valve or a preload valve. When sufficient pressure is available on the delivery side 3D of the main compressor 3, the valve 65 opens and the sealing gas flows through the valve 65 toward the dry gas seal 7, without entering the auxiliary compressor unit 25 through the second gas inlet 29. Conversely, if insufficient pressure is available on the delivery side 3D of the main compressor 3, such as when the main compressor 3 is stopped or started, the valve 65 closes, and the sealing gas flows from the delivery side 3D of the main compressor 3 into the auxiliary compressor unit 25 through the second gas inlet 29 and returns to the sealing gas feed circuit 9 through the outlet line 27 after pressurization. The valve 65 prevents the sealing gas from flowing back from the outlet line 27 to the inlet line 29.

[0071] Under rated operating conditions, the flow rate of sealing gas entering the sealing gas feed circuit 9 from the delivery side 3D of the main compressor 3 at high pressure (approximately 64 barA in the exemplary embodiment described above) is typically laminated to achieve a pressure suitable for feeding to the dry gas seal 7. The pressure drop caused by lamination represents an energy loss. In some embodiments, when the main compressor 3 operates under rated operating conditions, the sealing gas can be processed by the compression chamber 32D operating in expander mode, thereby causing the sealing gas entering the auxiliary compressor unit 25 through the second gas inlet 29 to expand and generate useful mechanical energy, which can be used to compress the recovered discharge sealing gas processed in the compression chambers 32A, 32B, and 32C. If the power generated by the expansion of the sealing gas in the expansion chamber 32D operating in expander mode is higher than the power required to compress the recovered sealing gas in the compression chambers 32A, 32B, and 32C, the electric motor driving the reciprocating compressor 26 can operate in generator mode, and the resulting electrical energy can be distributed on a power grid (not shown).

[0072] Under these conditions, at approximately 64 barA and approximately 45.9°C for approximately 10 m 3The sealing gas flow rate of / h can be expanded to 50.3 barA through chamber 32D, and together with the sealing gas recovered through the main exhaust recovery pipe 14 and processed by the compression chambers 32A, 32B and 32C of the auxiliary reciprocating compressor 26, it is returned to the sealing gas feed circuit 9 through outlet line 27.

[0073] Continue to refer to Figure 1 , Figure 3 Another embodiment of the sealed gas exhaust recovery system 21 is shown. Figure 3 The sealing gas exhaust recovery system 21 can be connected to the main compressor 3 and the sealing gas feed circuit 9, such as Figure 1 As shown. In Figure 3 In China, it has already Figure 2 The same or equivalent elements shown and described above are indicated by the same reference numerals and will not be described in detail again.

[0074] Figure 3 The sealed gas exhaust recovery system 21 and Figure 2 The main difference in the sealed gas exhaust recovery system 21 lies in the connection between the second compressor cylinder 26B and the rest of the auxiliary compressor unit 25. More specifically, in Figure 3 In one embodiment, the suction sides 32CS and 32DS of the third compression chamber 32C and the fourth compression chamber 32D are connected to each other. Similarly, the delivery sides 32CD and 32DD of the compression chambers 32C and 32D are connected to each other, so that the two compression chambers 32C and 32D operate in parallel.

[0075] If from Figure 3 As can be clearly seen from the description of the operation of the auxiliary compressor unit 25, in this embodiment, compression chambers 32A and 32B are part of a compressor section adapted to pressurize the sealing gas discharged from the dry gas seal 7, while compression chambers 32C and 32D are configured to pressurize the sealing gas discharged from the dry gas seal 7 and increase the pressure of the sealing gas from the sealing gas feed circuit 9 when the main compressor 3 is stopped or during its start-up or shutdown transients.

[0076] The sealing gas entering the auxiliary compressor unit 25 through the second gas inlet 29 is mixed with the flow supplied by the second compression chamber 32B of the first compressor cylinder 26A. Similarly, the compressed sealing gas supplied by both the third compression chamber 32C and the fourth chamber 32D of the second compressor cylinder 26B is combined and delivered to the sealing gas feed circuit 9 through the outlet line 27. A circulation line 57 with a circulation valve 59 and a cooler 61 can be provided to recirculate the gas in the second compressor cylinder 26B.

[0077] Furthermore, a pressure reducing valve 71 is installed along the second gas inlet 29, the purpose of which will be explained below. Finally, a return line 73 allows fluid communication between the delivery side 32BD of the second compression chamber 32B and the accumulation chamber 23. A pressure control valve 75 can be positioned along the return line 73 to selectively open and close the return line 73.

[0078] Figure 3 The auxiliary compressor unit 25 operates as follows. The parameter values ​​outlined below are for illustrative purposes only and should not be construed as limiting this disclosure.

[0079] With the main compressor 3 shut down, the sealing gas from the second gas inlet 29 flows at, for example, about 10m³. 3 The reduced flow rate, along with a pressure and temperature depending on the shutdown steady-state conditions, enters the auxiliary compressor unit 25 at approximately 47 barA and 45.9°C. The main exhaust gas from the dry gas seal 7 produces approximately 0.36 Sm at a pressure of approximately 1.3 barA. 3 / h of traffic.

[0080] The delivery pressure of the first compressor cylinder 26A can be approximately 18 bar. Therefore, the pressure of the sealing gas delivered to the auxiliary compressor unit 25 through the second gas inlet 29 will be reduced from approximately 47 barA to approximately 18 barA by lamination through the pressure reducing valve 71.

[0081] The delivery pressure of the second compressor cylinder 26B can be approximately 52.2 barA.

[0082] At startup, depending on the rotational speed of the main compressor 3, the flow rate of the sealing gas discharged from the dry gas seal 7 can be approximately 2.352 Sm at a pressure of approximately 1.3 barA. 3 / h to approximately 3.36 Sm at a pressure of approximately 1.5 barA. 3 Within the range of / h. The sealing gas entering the auxiliary compressor unit 25 through the second gas inlet 29 can have a pressure of about 47 barA and a flow rate of about 10 m. 3 The flow rate is approximately 10 m³ / h and the temperature is approximately 23.5°C. The flow rate in outlet line 27 is approximately 10 m³ / h at approximately 52 barA. 3 / h.

[0083] When rated operating conditions are met, the flow rate in the second gas inlet 29 will be approximately 0, and the flow rate of the sealing gas discharged from the dry gas seal 7 into the accumulation chamber 23 will be approximately 2.352 m at 1.3 bar A. 3 / h and approximately 3.36 Sm at 1.5 bar 3 Within the range of / h. In this embodiment, valve 65 will remain closed during normal operating conditions, and all sealing gas will be processed by auxiliary reciprocating compressor 26. Valve 65 may be an on / off valve, which will only open in the event of a failure of auxiliary compressor 26.

[0084] Although in the exemplary embodiments disclosed above, the increase in pressure of the sealing gas from the sealing gas feed circuit 9 during shutdown is provided by the second compressor cylinder 26B, in another embodiment (not shown), the first compressor cylinder 26A may be used to increase the pressure in the sealing gas feed circuit 9.

[0085] In other embodiments, the auxiliary compressor 26 may include one or more additional stages operating in compressor or expander mode. As an example, Figure 4 A diagram of another embodiment of the auxiliary compressor unit 25 is shown, including an additional reciprocating machine stage operating as an expander. Figure 4 In the figures, the same reference numerals are used to indicate the same as those in the figures below. Figure 3 The same elements and components are shown, and will not be described again.

[0086] exist Figure 4 In this design, the reciprocating compressor 26 includes a third compressor cylinder 26G, which includes a piston 26H arranged for reciprocating motion within the cylinder 26G. The piston 26H divides the cylinder 26G into a first chamber 32E and a second chamber 32F. If a compressed gas flow is available in a system equipped with the compressor unit 1, the flow can be expanded in the third compressor cylinder 26C of the reciprocating compressor 26, which operates as an expander and thus generates useful mechanical power, which can be converted into electrical power via a motor drivenly coupled to the reciprocating compressor. Alternatively, the generated mechanical power can be used to reduce the power required to drive the auxiliary reciprocating compressor 26.

[0087] Although Figure 4 The expander function is performed by a single double-acting compressor cylinder, but in other embodiments (not shown), more than one compressor cylinder and / or one or more single-acting compressor cylinders may be used in expander mode. In some embodiments, the double-acting compressor cylinder may be used in both compressor mode (in one of the two chambers) and expander mode (in the other of the two chambers).

[0088] The above-described embodiment of compressor unit 1 provides a sealing gas pressurization function when the main compressor 3 is stopped or during start-up or shutdown transients. The same auxiliary compressor unit 25 that provides the pressurization function also performs a main exhaust gas recovery function to recover waste sealing gas from the dry gas seal 7, thereby preventing the discharged sealing gas from being released into the environment.

[0089] According to another embodiment, the auxiliary compressor unit 25 can perform additional operations, such as recovering low-pressure (i.e., depressurized) process gas emissions from other components of the compressor unit 1 or from the compressor drive D. Typically, the low-pressure process gas can be discharged from one or more of the following: a pneumatic starter of the gas turbine engine, which acts as the drive for the main compressor 3; a fuel gas heating system adapted to heat the fuel gas before injecting it into the gas turbine engine. The low-pressure process gas generated by the aforementioned components can be collected in the accumulation chamber 23.

[0090] According to another embodiment, the auxiliary compressor unit 25 may also perform additional functions, such as removing process gas from the main compressor 3 when the main compressor 3 is shut down. For example, maintenance, repair, or replacement operations may require the compressor to be shut down. The process gas contained in the main compressor 3 should be discharged after shutdown.

[0091] Exhaust is achieved by closing isolation valves 5C and 5D on inlet pipe 5A and outlet pipe 5B, respectively. Once isolation valves 5C and 5D are closed, process gas can be removed from the main compressor 3 by starting the auxiliary compressor unit 25 and opening the on / off valve 102 in the compressor exhaust pipe 101. The compressor exhaust pipe 101 can be connected to the sealing gas feed circuit 9. In other embodiments, the compressor exhaust pipe and associated valve 102 can be directly connected upstream of isolation valve 5D to the delivery side 3D of the main compressor 3, such as... Figure 1 As shown in 101X and 102X. In other embodiments, the compressor discharge line and associated valves may be connected to the suction side 3S downstream of the isolation valve 5C, as... Figure 1 As shown at 101Y and 102Y.

[0092] Once exhaust pipe 101 (or 101X or 101Y) is opened, auxiliary compressor 26 can pump process gas from main compressor 3 and deliver the discharged process gas to inlet pipe 5A upstream of isolation valve 5C, or to outlet pipe 5B downstream of isolation valve 5D. The first option is preferred because auxiliary compressor 26 can operate at a lower compression ratio. The pressurized discharged process gas is delivered to inlet pipe 5A through connecting line 30. When the preset pressure value inside main compressor 3 has been reached, the process gas discharge ends, after which main compressor 3 can be turned on.

[0093] In the embodiments disclosed so far, the auxiliary compressor unit 25 is adapted to selectively or in combination perform, depending on the circumstances: perform a sealing gas pressurization function during the shutdown and / or start-up or shutdown transients of the main compressor 3; perform sealing gas main exhaust recovery from the dry gas seal 7; and discharge process gas from the main compressor 3 when the compressor is shut down. In other embodiments, the auxiliary compressor unit 25 may be configured to perform only the sealing gas pressurization function during the shutdown and / or start-up and shutdown transients of the main compressor 3, and discharge process gas from the main compressor 3 or recover the sealing gas discharged from the dry gas seal 7 when shut down. In both cases, the auxiliary compressor unit 25 performs the sealing gas pressurization function and the function of recovering process gas from the main compressor 3.

[0094] Figure 5 and Figure 6 A flowchart of the method for operating the compressor unit 1 described so far is shown.

[0095] More specifically, Figure 5 A method for operating compressor unit 1 is illustrated, wherein an auxiliary compressor unit 25 is used to recover sealing gas discharged from dry gas seal 7 and acts as a booster to increase the pressure of the sealing gas in the sealing gas feed circuit 9 when insufficient pressure is available on the delivery side 3D of the main compressor 3. The method includes step 201 of feeding sealing gas from the sealing gas feed circuit 9 to the dry gas seal 7 of the main compressor 3. Sealing gas discharged from the dry gas seal 7 at low pressure is recovered in step 202 and pressurized by means of the auxiliary compressor unit 25 (step 203) so that it can be returned to the dry gas seal 7 or to the main compressor 3 via the sealing gas feed circuit 9. Figure 5 The method also includes, for example, increasing the sealing gas pressure in the sealing gas feed circuit 9 when the main compressor 3 is shut down or during start-up or shutdown transients (step 204).

[0096] Figure 6 A method for operating compressor unit 1 is shown, wherein auxiliary compressor unit 25 is used to increase the sealing gas pressure in sealing gas feed circuit 9 when the pressure available at the delivery side 3D of main compressor 3 is insufficient, and to remove process gas from main compressor 3 when compressor is shut down. Figure 6 The method includes the steps of feeding sealing gas from the sealing gas feed circuit 9 to the dry gas seal 7 of the main compressor 3 (step 301), and increasing the sealing gas pressure in the sealing gas feed circuit 9, for example, during a shutdown of the main compressor 3 or whenever necessary (shutdown or start-up transients) (step 302). The method also includes, for example, the step of removing process gas from the main compressor 3 after shutdown (step 303).

[0097] It should be understood that, Figure 5 and Figure 6Both methods outlined in the flowchart can be performed by the same auxiliary compressor unit 25.

[0098] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. Those skilled in the art will understand that various changes, omissions, and additions may be made to the specific disclosure herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A compressor assembly (1), the compressor assembly comprising: The main compressor (3) has an intake side (3S), a delivery side (3D) and at least one dry gas seal (7). A sealing gas feed circuit (9) adapted to receive sealing gas from the delivery side (3D) of the main compressor (3) and feed the sealing gas to the at least one dry gas seal (7); and An auxiliary compressor unit (25) is adapted to increase the sealing gas pressure in the sealing gas feed circuit (9); and wherein the auxiliary compressor unit (25) is also adapted to receive a gas flow from the main compressor (3); The auxiliary compressor unit (25) includes a sealing gas inlet (29) fluidly connected to a main exhaust recovery pipe (14) of the sealing gas feed circuit (9) and a sealing gas outlet (27) fluidly connected to the sealing gas feed circuit (9), the main exhaust recovery pipe (14) being adapted to recover sealing gas discharged from the at least one dry gas seal (7) and feed the recovered sealing gas to the auxiliary compressor unit (25).

2. The compressor unit (1) according to claim 1, wherein the auxiliary compressor unit (25) includes a first compressor section (32D; 32C, 32D) adapted to receive sealing gas from the sealing gas feed circuit (9) at a sealing gas inlet pressure, the auxiliary compressor unit (25) adapted to return the sealing gas to the sealing gas feed circuit (9) at a sealing gas outlet pressure higher than the sealing gas inlet pressure; and wherein the auxiliary compressor unit (25) further includes at least one additional conduit (101; 101X; 101Y) adapted to deliver the gas flow from the main compressor (3) to a second compressor section (32A; 32B, 32C) of the auxiliary compressor unit (25).

3. The compressor device (1) according to claim 2, wherein the first compressor section (32D; 32C, 32D) includes a circulation line (57) that establishes a fluid connection between the delivery side (32DD) and the suction side (32DS) of the first compressor section (32D; 32C, 32D).

4. The compressor unit (1) according to any one of claims 1-3, wherein the auxiliary compressor unit (25) is adapted to remove process gas from the main compressor (3) after the main compressor (3) is shut down, so as to reduce the pressure of the main compressor (3).

5. The compressor unit (1) according to any one of claims 1-3, wherein the auxiliary compressor unit (25) is connected to the main compressor (3) via the main exhaust recovery pipe (14), and wherein the auxiliary compressor unit (25) is adapted to pressurize the recovered sealing gas and return the pressurized recovered sealing gas to the main compressor (3).

6. The compressor unit (1) according to claim 5, wherein the auxiliary compressor unit (25) is adapted to deliver the pressurized recovered sealing gas to the sealing gas feed circuit (9).

7. The compressor unit (1) according to any one of claims 1-3, wherein the auxiliary compressor unit (25) comprises a reciprocating compressor.

8. The compressor device (1) according to claim 7, wherein the auxiliary compressor (26) is a multi-stage reciprocating compressor.

9. The compressor device (1) according to claim 7, wherein the auxiliary compressor (26) comprises a plurality of double-acting compressor cylinders (26A, 26B).

10. The compressor device (1) according to claim 9, wherein at least one of the compressor cylinders (26A, 26B) is adapted to handle the gas flow delivered through the at least one additional conduit (101; 101X; 101Y) and to increase the pressure of the sealing gas from the sealing gas feed circuit (9).

11. The compressor device (1) according to claim 7, wherein the reciprocating compressor includes at least one cylinder (26G), the at least one cylinder being adapted to operate in expander mode and fluidly connected to a compressed gas source.

12. The compressor unit (1) according to any one of claims 1-3, the compressor unit further comprising a accumulator chamber (23) adapted to receive the gas flow from the main compressor (3) and fluidly connected to the auxiliary compressor unit (25).

13. The compressor device (1) according to claim 12, the compressor device further comprising a return line (49; 73) for fluidly connecting the delivery pipe (48; 45) of the auxiliary compressor unit (25) to the accumulation chamber (23).

14. The compressor unit (1) according to any one of claims 1-3, wherein the auxiliary compressor unit (25) includes a section (32D) configured to selectively operate as an expander adapted to expand the sealing gas flow entering the sealing gas feed circuit (9) before delivering the sealing gas to the at least one dry gas seal (7).

15. A method of operating a compressor arrangement (1), the compressor arrangement comprising: A main compressor (3) having an intake side (3S), a delivery side (3D), and at least one dry gas seal (7); a sealing gas feed circuit (9) adapted to receive sealing gas from the delivery side (3D) of the main compressor (3) and feed the sealing gas to the at least one dry gas seal (7); and an auxiliary compressor unit (25); the method comprising the following steps: The sealing gas is fed from the sealing gas feed circuit (9) to the at least one dry gas seal (7). The sealing gas discharged from the at least one dry gas seal (7) is recovered via the main exhaust recovery pipe (14); The recovered sealing gas is pressurized in the auxiliary compressor unit (25) and the pressurized recovered sealing gas is returned to the main compressor (3); The main compressor (3) receives sealing gas into the auxiliary compressor unit (25); The sealing gas pressure in the sealing gas feed circuit (9) is increased by using the auxiliary compressor unit (25).

16. The method of claim 15, wherein the step of recovering the sealing gas discharged from the at least one dry gas seal (7) includes the step of collecting the discharged sealing gas in a collection chamber (23) fluidly connected to the auxiliary compressor unit (25).

17. The method according to claim 15 or 16, wherein the auxiliary compressor unit (25) comprises an auxiliary compressor (26), the auxiliary compressor comprising at least a first compressor section (32D; 32C, 32D) and a second compressor section (32A, 32B, 32C); and wherein the step of pressurizing the recovered sealing gas is performed at least partially in the second compressor section (32A, 32B, 32C), and the step of increasing the pressure of the sealing gas is performed in the first compressor section (32D; 32C, 32D).

18. The method according to claim 17, wherein the auxiliary compressor (26) comprises a multi-stage reciprocating compressor.

19. The method of claim 15, further comprising: When the compressor unit is shut down, the auxiliary compressor unit (25) is used to remove process gas from the main compressor (3).

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