JP2012514707A - Compressor operation method and apparatus - Google Patents

Abstract

  The present invention provides a method and apparatus for operating a compressor (100) to reduce the relief load during a clogged exit event, the method comprising: (a) one or more of the methods Of compressor feed streams (10, 20, 30, 40) are passed through one or more inlets (18, 28, 38, 48) of the first compressor (100), and each compressor feed stream (10 , 20, 30, 40) pass through the compressor supply valve (12, 22, 32, 42), and (b) the discharge flow compressed at the outlet (105) of the first compressor (100) ( 150) compressing one or more compressor feed streams (10, 20, 30, 40) with a first compressor (100) to supply (c), and (c) a first compressor (100). ) Monitoring a first indicator of a blocked exit event of (d); When the first indicator of occluded outlet events of the first compressor (100) is detected, at least a step of instructing the closing of compressor supply valve (12, 22, 32, 42).

Description

  The present invention relates to a method of operating a compressor to reduce the relief load during a blocked outlet event, and to reduce the relief load during a blocked outlet event of the compressor. The apparatus of this is provided.

  A common use for compressors is in the form of refrigerant compressors, which are used, for example, to compress refrigerant streams during liquefaction of natural gas (NG). The refrigerant stream is used to extract heat from the natural gas by liquefaction, for example, by indirectly exchanging the refrigerant with respect to the natural gas in one or more heat exchangers.

  Natural gas is not only a source of various hydrocarbon compounds, but also a useful fuel source. For several reasons, it is often desirable to liquefy natural gas at a liquefied natural gas (LNG) plant at or near the source of the natural gas stream. As an example, natural gas can be stored more easily in liquid form than in gaseous form and transported over long distances because it occupies a smaller volume and does not need to be stored at high pressure.

  Typically, natural gas is pre-pressurized to enter an LNG plant and generate a purified feed stream suitable for liquefaction at cryogenic temperatures. The purified gas is processed through multiple cooling stages using a heat exchanger to gradually reduce its temperature until liquefaction is achieved. The liquid natural gas is then further cooled and expanded to a final atmospheric pressure suitable for storage and transport.

  A cooling stage for liquefaction of natural gas utilizes one or more refrigerants circulated in one or more refrigerant circuits. The refrigerant circuit may comprise one or more refrigerant compressors, one or more heat exchangers, and one or more cooling devices. In such a circuit, the at least partially evaporated refrigerant stream can be compressed with a refrigerant compressor to provide a compressed refrigerant discharge stream. The compressed refrigerant stream can then be cooled with a cooling device, such as an air or water cooler, or with a heat exchanger relative to other refrigerant streams to provide a cooled refrigerant stream. The cooled refrigerant stream can then optionally be expanded and then passed to a heat exchanger that can cool the natural gas.

  If a blockage or restriction occurs downstream of the compressor discharge (so-called “clogged outlet event”) and normal operation continues, the pressure of the compressed refrigerant discharge stream potentially increases above the design pressure However, mechanical failure and containment losses can occur. As a result, the compressed refrigerant discharge flow is usually accompanied by a pressure relief valve that allows the compressed refrigerant discharge flow to pass through the flare system before mechanical failure can occur. The flare system must be sized to handle the relief load expected in the event of such an event. Piping and flare systems can be a source of significant capital costs. Therefore, it is desirable to minimize the size of the piping and flare system required to handle such flows.

  U.S. Patent Application Publication No. 2005/0022552 discloses a gas compression device comprising a gas compressor and a drive device, where the drive device is used when the output demand of the gas compressor exceeds the maximum output of the drive device. The recycle line has a pressure relief device in fluid communication with the outlet of the gas compressor. The pressure relief device is in the recycle line in addition to any anti-surge valve. The recycle line receives a flow of compressed gas from upstream of the compressor outlet. The pressure relief device opens when the discharge pressure from the outlet reaches a specified pressure, supplying compressed gas to the inlet of the gas compressor, thereby increasing the mass flow rate through the compressor and adjusting the drive .

US Patent Application Publication No. 2005/0022552 U.S. Pat. No. 4,404,008

  The apparatus disclosed in US 2005/0022552 operates to open a recycle line that increases mass flow through the compressor. This will require more compressor output and, as a result, will reach the maximum drive output at some point resulting in reduced speed. This can also reduce the discharge pressure before it reaches the design pressure of the system. However, this depends on normal operating pressure, design pressure, and maximum output of the drive. For example, if there are more drive outputs available, this can lead to overpressure and subsequent damage to the compressor and associated piping system, and loss due to containment.

In a first aspect, the present invention provides a method and apparatus for operating a compressor to reduce relief load during a blocked outlet event, the method comprising:
(A) passing one or more compressor feed streams to one or more inlets of the first compressor, each compressor feed stream passing through a compressor feed valve;
(B) compressing one or more compressor feed streams with a first compressor to provide a compressed discharge stream at an outlet of the first compressor;
(C) monitoring a first indicator of a clogged outlet event of the first compressor;
(D) detecting at least a first indicator of a closed first outlet event of the first compressor, instructing to close the compressor supply valve.

In a second aspect, the present invention provides an apparatus for reducing the relief load during a compressor closed outlet event:
A first compression having an outlet for a compressed discharge stream and one or more inlets for one or more compressor feed streams, each compressor feed stream passing through a compressor feed valve Machine,
A first controller in communication with the first device to provide a first indication of a first compressor blocked outlet event, the first compressor blocked outlet event And a first controller further in communication with each compressor supply valve so as to transmit a first signal for closing each compressor supply valve when detecting the first index.

  Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying non-limiting drawings.

1 is a schematic diagram of a method and apparatus for operating a compressor according to one embodiment. FIG. FIG. 3 is a schematic diagram of a method and apparatus for operating a refrigerant compressor according to a second embodiment.

  For the purposes of this description, a single reference number is assigned to the line as well as the flow that is led in this line.

  The method and apparatus are intended to reduce the relief flow associated with a compressor plugged outlet event. Upon detection of the first indication of a closed outlet event, normal operation of the compressor cycle is stopped and the compressor supply valve is instructed to close.

  Mass flow through the compressor is sought to be reduced by indicating the closure of the compressor supply valve when a first indication of a closed outlet event of the first compressor is detected. When one of the compressor supply valves is closed, the relief flow is reduced.

  In the context of this disclosure, “close” of the compressor supply valve and “to close” the compressor supply valve preferably cause the compressor supply flow to pass through the compressor supply valve. It means "to shut" each "the shunting" of the compressor supply valve so that it is essentially completely closed. Any compressor supply valve whose closure may be commanded may be provided in the form of a trip valve under snap action control (sometimes referred to as two-position control) relative to the control valve where throttling occurs. preferable.

  Referring to the drawings, FIG. 1 shows a method and apparatus 1 for operating a compressor 100 having a first compressor feed stream 10 and a second compressor feed stream 20 according to a first embodiment. .

  However, the methods disclosed herein can be used in any system having a compressor consisting of two or more compressor feed streams, such as n feed streams, where n is 2 or greater. And more preferably an integer in the range of 2 to 6.

  Each compressor supply stream 10, 20 passes through a compressor supply valve 12, 22. Two supply valves are shown in FIG. However, if there are n compressor feed streams, then n compressor feed valves with one for each feed stream may be provided. FIG. 1 shows a first compressor supply stream 10 passing through a first compressor supply valve 12 and a second compressor supply stream 20 passing through a second compressor supply valve 22.

  The first compressor 100 can be a single stage compressor or a multistage compressor. Examples of multistage compressors are those in which two or more compression stages are contained in a single casing, or are connected to a common mechanical drive shaft so that the multistage compressor continuously compresses the compressor feed stream There is something to be arranged. The first compressor 100 is known in the art such as a centrifugal compressor, diagonal compressor, axial compressor, reciprocating compressor, rotary screw compressor, rotary vane compressor, scroll compressor, or diaphragm compressor. Can be any compressor. In the embodiment of FIG. 1, two compression stages are shown.

  The first compressor feed stream 10 enters the first compressor 100 at the first inlet 18. A second compressor feed stream 20 that is at a higher pressure than the first compressor feed stream enters the first compressor 100 at a second inlet 28. The first compressor feed stream 10 and the second compressor feed stream 20 are compressed to provide a compressed discharge stream 150 at the outlet 105 of the first compressor 100. The first compressor 100 may be driven by a first drive device 200 that will be described in more detail below.

  The compressed discharge stream 150 may be supplied with a recycle stream 110, 120 for each compressor feed stream 10, 20. Thus, n recycle streams can be fed for n compressor feed streams.

  Each recycle stream 10, 20 connects a discharge stream 150 compressed between a respective inlet 18, 28 and a respective compressor supply valve 12, 22 to the compressor supply stream 10, 20. Each recycle stream 10, 20 is provided with a recycle expansion device 112, 122, such as a Joule-Thomson valve. FIG. 1 shows a compressed discharge stream that passes through a first recycle expansion device 112 before connecting to a first compressor supply stream 10 between a first compressor supply valve 12 and a first inlet 18. A first recycle stream 110 from 150 is shown. Similarly, FIG. 1 shows that compressed between the second compressor supply valve 22 and the second inlet 28 passes through the second recycle expansion device 122 before connecting to the second compressor supply stream 20. A second recycle stream 120 from the discharged stream 150 is shown.

  The recycle streams 110, 120 can protect the first compressor from damage due to events that may occur when surge, i.e., the compressor feed stream flow is too low, resulting in a rapid pulsation of the flow. This event opens the recycle valves 112, 122 to return at least a portion of the compressed discharge stream 150 to the inlets 18, 28 of the first compressor 150, thereby entering the first compressor 150. Can be mitigated by increasing the mass flow.

  A portion of the compressed discharge stream 150 that is not reused in the recycle stream 110, 120 is passed downstream as a continued compressed stream 160. Thus, the continued compressed stream 160 is the difference between the total flow rate of the compressed discharge stream 150 and any recycle stream returned to the suction side of the first compressor 100 via the recycle streams 110, 120. Represents.

  The blockage or restriction downstream of the discharge of the first compressor 100 increases the pressure of the compressed discharge stream 150 and any downstream flow between the first compressor 100 and the blockage or restriction. Can do. A so-called compressor clogged outlet event can result in overpressure at the outlet of the first compressor, and if measures are not taken to prevent pressure increases, this can exceed design specifications and cause mechanical failure. Can cause.

  Thus, a blocked exit event is defined herein as a blockage or flow restriction downstream of the first compressor discharge, which is compressed below the flow required for normal operation. Reduced discharge flow, thus leading to an increase in pressure at the outlet of the first compressor.

  A blocked exit event can occur for several reasons, depending on the nature of the first compressor 100 and the circuit in which the compressor is operating. Examples of compressor closed outlet events include failure of a valve in fluid communication with the compressed discharge stream 150, such as failure of the discharge isolation valve 350 in the closed position, fluid communication with the compressed discharge stream 150. There is a loss of the condensing capacity of any condenser that is in fluid communication with the compressed discharge stream 150 or a blockage of a unit such as a condenser that is in operation.

  In known systems that do not take steps to handle compressor clogged outlet events, the compressor cycle continues to operate so that the compressor feed stream continues to flow to the compressor inlet. In addition, any anti-surge control system present opens any recycle valve. This causes an increase in discharge pressure and also an increase in suction pressure if any recycle valve is opened. If sufficient output can be supplied to the compressor, the discharge pressure will continue to rise and may exceed the system design pressure if a relief valve is not provided.

  Conventionally, such a relief valve is connected to a flare system, which generates the entire relief flow from a closed outlet event, i.e., from all compression of the compressor feed stream, at the compressor outlet. It is dimensioned to handle mass flows that must be relieved to prevent further pressure increases.

  FIG. 1 discloses a preferred embodiment in which an optional pressure relief valve 250 is provided in fluid communication with the compressed discharge stream 150. In the illustrated embodiment, the pressure relief valve 250 is connected to a continuing compressed stream 160 that is not recycled to the inlet of the first compressor 100 and is a compressed discharge stream. Supplied by this part of 150. The pressure relief valve 250 can be connected to the flare system 300. Flare system 300 can include a flare stack and associated piping (not shown).

  The methods and apparatus disclosed herein provide at least one, and more preferably two, barrier systems for protection of the apparatus 1 including the first compressor 100 and the compressed discharge stream 150. .

  The first barrier system handles the increase in pressure of the compressed discharge stream 150 after the closed outlet event by indicating the closing of the compressor supply valves 12,22. This prevents further increases in pressure at the outlet 105 of the first compressor 100 by preventing the introduction of additional mass flow into the first compressor 150 via the compressor feed streams 10, 20. Is intended.

  The first barrier system monitors a first indicator of a blocked outlet event of the first compressor. The first indicator is a selected discharge pressure of the compressed discharge stream 150, a selected discharge temperature of the compressed discharge stream 150, a selected output of the first compressor 100, one or more compressions. There may be one or more of a group comprising selected suction pressures of the machine feed streams 10, 20 and selected suction temperatures of the one or more compressor feed streams 10, 20.

  The first indicator should preferably be selective for a blocked exit event and non-selective for other events that occur under normal operating conditions in the absence of any blocked exit event. is there. For example, if a process measurable quantity (eg, discharge pressure, or other measurable quantity listed in the above group) is used, then the selected value of this measurable quantity is normal operating conditions The normal variation of the process measurable amount that can occur below does not reach the selected value and / or does not cross without the occluded exit, only enough to cause detection of the first indicator of the occluded exit event Should be high or low. The selected value should preferably be high or low enough to reach or cross only the selected value only in the case of an exit event where the process measurable quantity in question is occluded.

  Preferably, the first indicator of the first compressor plugged outlet event comprises, more preferably consists of, the selected discharge pressure of the compressed discharge stream 150. This discharge pressure is one of the most direct indications of compressor plugged outlet events and is believed to be relatively easily measurable. Thus, for example, the first indicator can be a selected pressure of the compressed discharge stream 150. When this selected pressure is reached, the compressor supply valves 12, 22 are instructed to close. Some compressor supply valves 12, 22 from zero to all of the compressor supply valves 12, 22 can be closed as indicated. Zero, some or all of the compressor supply valves 12, 22 may not be closed.

Accordingly, the methods disclosed herein are:
(A) A first compressor supply stream 10 having a first compressor supply valve 12 is passed through a first inlet 18 of the first compressor 100 and a second compressor supply valve 22 is provided. Passing two compressor feed streams 20 to a second inlet 28 of the first compressor 100;
(B) The first compressor 100 provides a first compressor feed stream 10 and a second compressor feed stream 20 to supply a compressed discharge stream 150 at the outlet 105 of the first compressor 100. Compressing, and
(C) monitoring a first indicator of a blocked outlet event of the first compressor 100;
(D) indicates that both the first compressor supply valve 12 and the second compressor supply valve 22 are closed when a first indication of a closed outlet event of the first compressor 100 is detected; At least a step of performing.

  There are a number of different scenarios, each with its own probability, when directing the closure of the compressor supply valves 12, 22 in the first barrier system.

  For example, in the embodiment of FIG. 1, both the first compressor supply valve 12 and the second compressor supply valve 22 may close in response to being instructed to do so. One of the first compressor supply valve 12 and the second compressor supply valve 22 may be closed, or both the first compressor supply valve 12 and the second compressor supply valve 22 are May not close. For example, if the supply valves 12, 22 are electronically actuated valves, one or more of the supply valves may not be closed due to valve freezing or failure of an electronic indication signal reaching the valve.

  The probability that each scenario will occur can be calculated by performing an appropriate risk assessment. If the probability that all of the compressor supply valves 12, 22 will close well is acceptable and the probability that one or more of the compressor supply valves 12, 22 cannot close is low enough, In this case, the pressure relief valve 250 and the flare system 300 will not be required.

  If the probability that at least one of the compressor supply valves 12, 22 cannot be closed is unacceptably high, then at least one of the compressor supply streams 10, 20 will continue to the first compressor 100. There is a high probability of being supplied. During a closed outlet event, this will result in an increase in the pressure at the outlet 105 of the first compressor 100 and thus the compressed discharge stream 150 and the compressed continuous stream 160. In order to relieve this pressure, a pressure relief valve 250 in fluid communication with the compressed discharge stream 150 may be provided. The pressure relief valve 250 is configured to open in response to an increase in discharge pressure as a result of a blocked outlet event, forming an outlet for the continued compressed flow 160. The pressure relief valve 250 may be connected to the flare system 300 to process a portion of the compressed continued flow 160 that passes through the pressure relief valve 250.

  In this case, the probability that one or more of the compressor supply valves 12, 22 will close well is acceptable and the probability that none of the compressor supply valves will close is acceptable. The size of one or both of the flare system 300 and the pressure relief valve 250 can be reduced compared to the size designed to accept all outlets of the compressor feed streams 10,20.

  For example, when the probability that each of the supply valves 12 and 22 cannot be closed is the same, the probability that the supply valve whose number has been increased cannot be closed is low. In the case of FIG. 1 with two supply valves, if each supply valve has a probability of not being able to close 0.1, the probability that both supply valves cannot be closed is 0.01, and one is The probability that it cannot be closed is 0.18, the probability that one or both cannot be closed is 0.19, and the probability that either can be closed is 0.81. Thus, in this case, the device can be provided without the pressure relief valve 250 and flare system 300 if a probability of 0.19 represents an acceptable low risk.

  However, a probability of 0.19 that one or both of the supply valves cannot be closed is determined to represent an unacceptably high risk, and a probability of 0.01 that both supply valves 12, 22 cannot be closed is acceptable. In this case, a pressure relief valve 250 may be provided in fluid communication with the compressed discharge stream 150 if it represents a reasonably low risk. In this case, the pressure relief valve 250 can be connected to the flare system 300. One or both of the pressure relief valve 250 and the flare system 300 may be dimensioned to at least receive the relief flow from the first compressor. In the embodiment of FIG. 1, the relief flow corresponds to a continued compressed flow 160 generated by the compressor feed stream at maximum flow rate.

  If the probability of 0.01 that both of the supply valves cannot be closed represents an unacceptably high risk, then one or both of the pressure relief valve 250 and the flare system 300 are both Sized to receive at least the flow from the continued compressed stream 160 generated by the compressor feed stream 10,20.

  In one embodiment, the first barrier system may be provided with a first safety criterion, which may be that of the compressor supply valves 10, 20 that can be tolerated for failure of closure. Specify the number.

  For example, the first safety criterion is set as the largest number of compressor supply valves that can be accepted as incapable of closing if they are instructed to close without causing an unacceptable risk, such as causing loss due to containment. obtain. Thus, this safety criterion can be used to calculate the minimum capacity of one or both of any pressure relief valve 250 and any flare system 300.

  If the first safety criterion is set to zero supply flow valve failure, no pressure relief valve 250 or flare system 300 is required. This means that the closure failure of one or more of the supply valves has been calculated to be as low as acceptable by risk assessment.

  Currently, one or both of the pressure relief valve 250 and the flare system 300 is in contact with the first compressor 100 during the failure of the number of supply valves 12, 22 as defined in the first safety standard. Can be designed to accept at least the relief flow resulting from the compression in the compressor feed streams 10, 20 that follow.

  Thus, in general, the term “relief flow” must be relieved after a closed outlet event to prevent further pressure increase between the outlet 105 of the first compressor 100 and the blockage or flow restriction. Defined as a flow. In the embodiment of FIG. 1, the relief flow is equivalent to the flow rate of the continued compressed flow 160. This can be contrasted with the flow of the compressed discharge stream 150, which will also include the mass flow supplied to the first compressor 100 by any recycle stream 110, 120.

  For example, if there are n compressor supply valves 12, 22 and n is an integer greater than or equal to 1, the first safety criterion is the failure of several m of the compressor supply valves 12, 22 to be closed. M is an integer in the range from 0 to n, more preferably m is an integer in the range from 0 to (n−1), or 1 to n, and More preferably, m is an integer ranging from 1 to (n-1).

  Thus, in general, the relief flow for the first safety criterion is the flow resulting from the compression in the first compressor 100 of m compressor feed streams 10, 20 in which the feed valves 12, 22 cannot be closed. Can be defined.

  Thus, in the case of the first safety criterion when m = n, the risk assessment is unacceptably high in the probability that exactly one of the supply valves cannot be closed, whereby the pressure relief valve 250 and the flare system It is clear that one or both of 300 are dimensioned to at least receive the relief flow generated by the compression of all of the compressor feed streams 10,20.

  In the case of the first safety criterion when m <n, m + 1 or more failures of the compressor supply valves 12, 22 to be closed have been calculated in the risk assessment to be acceptable low. . Accordingly, the pressure relief valve 250 and / or the flare system 300 can be dimensioned to at least receive the relief flow generated by the compressor feed stream 10,20.

  The first safety criteria is specified for special equipment and configurations. The value m represents an acceptable risk of failure of m + 1 or more valves to be closed, represents a higher probability of failure of m valves to be closed and represents an unacceptable risk, while an acceptable low probability Is statistically determined by risk assessment to have

In one embodiment, the first safety criterion, m, is a probabilistic analysis for n valves, for example:
(I) calculating the probability for each of the n + 1 possible outcomes of the number of valves that are closed or left open, which is 0 to n of the supply valves that cannot be closed, for example cannot be closed Steps representing 0, 1, 2, 3, etc. of the supply valves;
(Ii) “0”, “1 or more” of the supply valves to “n−1 or more” and “n” cannot be closed, for example, “0”, “1” of the supply valves Calculating total probabilities for scenarios where “above”, “2 or more”, “3 or more” etc. cannot be closed,
(Iii) selecting a scenario with the highest probability calculated in step (ii) representing an acceptable risk if one exists;
(Iv) a) if safety criteria are set to 0 valves, not all of the probabilities calculated in step (ii) represent acceptable risk, or b) safety criteria is n If all of the probabilities calculated in step (ii) do not represent an acceptable risk when set to a single valve, the least number of valves in the range selected in step (iii) And setting a first safety criterion with one less valve failure than the number.

  Next, the selection of the first safety criterion will be described by way of example for a system having four supply valves and using a fully virtual valve failure and an acceptable risk probability. The probability of a scenario with 4 supply valves, each with a virtual and independent probability of not closing 0.1 of 0.1, a scenario where 0, 1, 2, 3 and 4 supply valves cannot be closed is , 0.656, 0.292, 0.049, 0.004, and 0.0001, respectively (step (i)). The total probability that 0, 1 or more, 2 or more, 3 or more and 4 supply valves cannot be closed is then 0.6561, 0.3429, 0.0523, 0.0037 and 0.0001, respectively. (Step (ii)). If the acceptable risk is set to a scenario probability of 0.01 or less, then in this case, 3 or more supply valves that cannot be closed are calculated to occur with the highest probability determined to represent acceptable risk. (Step iii)). Safety criteria may be set for two supply valves that cannot be closed (step (iv)).

  Returning to FIG. 1, the first safety criterion is defined as m = 0 faults of the compressor supply flow valves 12, 22 to be closed, ie all compressor supply flow valves 12, In situations where 22 is closed as indicated, a device is provided in which it has been determined that there is an acceptable low risk of one or more valves that cannot be closed. This is because the pressure relief valve 250 and flare system 300 are unnecessary and need not be present, or there is a shared flare system 300 shared by multiple process units, ie, two or more compressors. This means that such a shared flare system need not be dimensioned to accept the relief flow generated by either of the compressor feed streams 10,20.

  In the embodiment of FIG. 1, there are two compressor feed streams 10, 20 and two compressor feed valves 12, 22. The safety criteria for the failure of one of the compressor supply valves 12, 22 to be closed is such that the probability of this event occurring is unacceptably high and at the same time the probability that both of the compressor supply valves 12, 22 cannot be closed. It can also be selected if it is low enough.

  One or both of the pressure relief valve 250 and the flare system 300 is such that it at least accepts a first safety criterion, i.e. a relief flow generated by the failure of one of the two supply valves 12, 22 being closed. Can be made to dimensions. Thus, the flare system handles the relief flow generated by a single compressor feed stream, ie, one or other of the first compressor feed stream 10 and the second compressor feed stream 20. It is made to such a dimension.

  In situations where the compressor feed streams 10, 20 have different mass flows, the flare system should be sized to handle the relief load generated by the compressor feed streams 10, 20 having a larger mass flow. is there. In general, if the safety criteria is set for m supply valves 12, 22 that cannot be opened, in this case the flare system 300 will handle the relief load generated by m flows having a larger mass flow. Should be dimensioned to

  In a preferred embodiment, at least the pressure relief valve 250 is sized to receive at least the relief flow generated by the first safety criteria.

  In a further embodiment, the pressure relief valve 250 is dimensioned to receive at least the relief flow generated by the first safety criteria, while the flare system 300 size is the relief generated by the first safety criteria. It can be large enough to accept a flow larger than the flow. Such a situation is that the flare system 300 is shared with one or more other processing devices that give a limiting example for the capacity of the flare system 300, i.e. the other processing devices are subject to the first safety criteria. This can happen when a flare capacity greater than the generated flow is required. This is the case, for example, where the method and apparatus disclosed herein is used to protect a main refrigerant compressor in an LNG liquefaction plant, where the flare system is a limiting example from the propane precooling stage, which is a limited example. This can happen if it is made with acceptable dimensions.

  In a further embodiment where the pressure relief valve 250 is dimensioned to at least receive the relief flow generated by the first safety criteria, the flare system 300 is less in volume than the relief flow generated by the first safety criteria. Can be dimensioned to accept In this case, a closed outlet event will occur and protection against loss due to containment will be achieved if the pressure relief valve 250 is to be opened. However, the relief flow generated by the first safety criteria will exceed the capacity of the flare system 300, thereby causing excessive flare to the flare system 300, such as a flare stack, and potential It becomes thermal radiation damage.

  In other embodiments, both the pressure relief valve 250 and the flare system 300 have a minimum size to at least accept the relief flow generated by the first safety criteria.

  If the first safety criterion has m valves that cannot be closed and the value m is less than the total number n of supply valves, one of the pressure relief valve 250 and the flare system 300 configured to accept a relief flow It will be apparent that one or both sizes can be reduced compared to pressure relief valves and / or flare systems that are sized to accept relief loads from all combinations of compressor feed streams 10,20. This can generate significant CAPEX savings because smaller pressure relief valves and flare systems, particularly flare stacks, are significantly less expensive than larger size units.

  Accordingly, in a further preferred embodiment that is applicable to all aspects disclosed herein, one or both of the pressure relief valve 250 and the flare system 300 is connected to the n compressors in the first compressor 100. It may be dimensioned to accept a smaller amount than the flow generated from compression of the compressor feed streams 10,20. Even more preferably, one or both of the pressure relief valve 250 and the flare system 300 is at least a relief flow of relief flow generated by the first safety criteria, and n in the first compressor 100. It may be dimensioned to accept a smaller amount than the flow generated from all compression of the compressor feed streams 10,20.

  In other embodiments, one or both of pressure relief valve 250 and flare system 300 may be dimensioned to at most substantially accept the relief flow generated by the first safety criteria. For example, one or both of the pressure relief valve 250 and the flare system 300 will preferably accept at most 120%, more preferably 110%, and even more preferably 105% of the relief flow generated by the first safety criteria. Can be made to any size.

  In view of other methods, the method and apparatus disclosed herein may be used when a flare system is installed in a facility designed to handle the entire relief load generated from all of the compressor feed stream. Advantageously, the system capacity can be freed for other purposes when the number m of feed flow valves that cannot be closed by the first safety criterion is smaller than the total number n of feed flow valves.

  The first barrier system may be provided by an Instrumental Protective Function (IPF). This comprises a first monitoring device P1 that monitors a first indicator of a blocked outlet event of the first compressor 100, and a first controller XC1. The first indicator is a selected discharge pressure of the compressed discharge stream 150, a selected discharge temperature of the compressed discharge stream 150, a selected output of the first compressor 100, one or more compressions. There may be one or more of a group comprising selected suction pressures of the machine feed streams 10, 20 and selected suction temperatures of the one or more compressor feed streams 10, 20. The first monitoring device P1 can be set by a first selected value, such as pressure, temperature or compressor output, which is a first indicator of a blocked outlet event. When the first selected value is detected, the first monitoring device P1 can send a first signal to the first controller XC1.

  For example, the first monitoring device P1 can be a pressure sensor in the compressed discharge flow 150. A first signal is sent to the first controller XC1 when the pressure reaches a first selected value representing an occluded outlet event.

  Upon receiving a first signal indicating that a closed outlet event is occurring, the first controller XC1 sends a first indication signal to the compressor supply valves 12, 22 which may be electrically actuated valves. Can be sent and instructed to close them.

  Furthermore, the first controller XC1 can send a second indication signal to the recycle valves 112, 122, which can be electrically actuated valves, and the inlet 18 of the first compressor 100 to prevent surges. , 28 to direct the release of the compressed discharge stream 120 to allow recycling. However, the first barrier system can be any system that can protect the first compressor against surges, or other that can protect the first compressor against high discharge temperatures, vibrations, etc. It is preferably completely independent from the system.

  If successful, the first barrier system can prevent further increases in pressure at the outlet 105 of the first compressor 100. This occurs when all of the compressor supply valves 12, 22 close well as indicated.

  If one or more of the compressor supply valves cannot be closed, the first compressor discharge pressure can be increased until any second barrier system is engaged or the pressure relief valve 250 is opened.

  The second barrier system disclosed herein is preferably independent of the first barrier system. The second barrier system should also be independent of any compressor protection system such as a surge protection system. The purpose of the second barrier system is to reduce the compression output of the first compressor 100 when a second indication of a blocked outlet event of the first compressor is detected. This can include reducing the compression output of the first compressor to zero such that operation of the first compressor 100 is stopped.

  The second barrier system monitors a second indicator of a blocked outlet event of the first compressor 100. The second indicator is a selected discharge pressure of the compressed discharge stream 150, a selected discharge temperature of the compressed discharge stream 150, a selected output of the first compressor 100, one or more compressions. There may be one or more of a group comprising selected suction pressures of the machine feed streams 10, 20 and selected suction temperatures of the one or more compressor feed streams 10, 20.

  The second indicator can be the same as or different from the first indicator described above. Further, the first and second indicators can be selected to be the same value, such as temperature, pressure, or first compressor output, but different values. Thus, the selection of the second indicator is under the same conditions as the first barrier system, eg, before the first barrier system if the same operating criteria are used for both systems, or the first barrier. A second barrier system can be provided that is configured to operate after the system. For example, the first and second indications of the blocked outlet event of the first compressor 100 may be selected in the form of the same or different pressure levels of the compressed discharge stream 150.

  Upon detecting a second indicator of a blocked outlet event of the first compressor, a reduction in the compression output of the first compressor 100 is indicated. In a preferred embodiment, the compressed output is instructed to be reduced to zero.

  The first compressor 100 can be mechanically driven by a first drive device 200, which can be an electric drive device as shown in FIG. Alternatively, the compressor 100 can be mechanically driven by a gas turbine or a steam turbine (not shown). The reduction of the compressed output is achieved by one or more of the following procedures: reducing the speed of the first drive device 200 and reducing the supply of output to the first drive device 200. obtain.

  If the first drive device 200 is an electric drive device, the electrical output supplied to the first drive device can be reduced, or if it is desired to reduce the compression output to zero, The circuit for supplying electrical power to the first drive can be turned off as shown by switch 210 in FIG.

  If the first compressor 100 is mechanically driven by a gas turbine or a steam turbine, the supply of fuel to the gas turbine or the supply of steam to the steam turbine can be reduced, so that the first The speed of one driving device can be reduced. If desired, the fuel or steam supply can be completely stopped, stopping the first drive 200 and thereby stopping the operation of the first compressor 100.

  The reduction in the output of the first compressor 100 can prevent a further increase in pressure at the compressor outlet 105.

  The second barrier system can be provided by an Instrumental Protective Function (IPF). This comprises a second monitoring device P2 for monitoring a second indicator of a blocked outlet event of the first compressor 100, and a second controller XC2. The second monitoring device P2 can be set by a second selected value, such as pressure, temperature or compressor output, which is a second indicator of a blocked outlet event. When the second selected value is detected, the second monitoring device P2 can send a second signal to the second controller XC2.

  For example, the second monitoring device P2 can be a pressure sensor in the compressed discharge stream 150. In order to achieve independence from the first barrier system, the second monitoring device P2 is preferably a device separate from the first monitoring device P1. When the pressure reaches a second selected value, a second signal is sent to the second controller XC2 indicating that an occluded outlet event has occurred.

  Upon receipt of the second signal, the second controller XC2 may send a third indication signal to an appropriate unit to reduce the first compressor output. For example, the third indicating signal may be an electrically operated valve, such as a valve, preferably a solenoid valve, to limit the flow of fuel or steam to the gas turbine or steam turbine first drive 200, respectively. Can be sent to. If the first drive device 200 is an electric motor, in this case, the third instruction signal is sent to the electric motor to reduce the output or to the distribution system to reduce the electric output supplied to the electric drive device. Or, if it is intended to stop the drive completely, may be supplied to an electrical switch 210 of the output circuit of the electric drive.

  In a preferred embodiment, the second barrier system is operated in combination with the first barrier system. For example, to a level such that a first indicator of a clogged outlet event will occur before that of the second indicator, eg, to a discharge pressure of the first compressor that is lower than the second indicator. If set, in this case, the compressor supply valves 12, 22 are instructed to close upon detection of the first indication of a blocked outlet event. If all of the compressor supply valves 12, 22 close well, then in this case any further increase in pressure at the outlet 105 of the first compressor 100 cannot occur and the first barrier system is Is working well.

  However, if one or more of the compressor supply valves 12, 22 cannot be closed, the pressure at the outlet 105 of the first compressor 100 will continue to rise until a second indication of a closed outlet event is reached. . When the second index is reached, the second barrier system is activated and instructs to reduce the first compressor output. More preferably, the indication is given to reduce the first compressor output to zero.

  In the case of a gas turbine or steam turbine first drive, the indication is sent to close one or more valves in the fuel gas or steam flow, respectively, such as a steam control valve and a trip valve. Similarly, if the first drive device 200 is an electric motor, the indication may be sent to turn off one or more switches 210 to turn off the electrical circuit that powers the first drive device 200. . If at least one of these valves closes successfully or the switch 210 is turned off successfully, the first drive 200 stops and the first compressor 100 stops operating. Any further increase in pressure at the discharge of the first compressor is stopped.

  The combination of the first barrier system and the second barrier system can be a significant decrease in the probability that the pressure at the outlet of the compressor will increase beyond the design pressure after a closed outlet event.

  The first set pressure of the pressure relief valve 250 is a level above that of the first index to ensure that the supply valves 12, 22 are instructed to close before the pressure relief valve 250 is opened. Should be set to

  In a preferred embodiment, the first set pressure of the pressure relief valve 250 is a first indication of a blocked outlet event of the first barrier system, and any second if a second barrier system is present. It is set at a level that exceeds the indicator of.

  If the first safety criterion is still met, but not all of the supply valves 12, 22 are closed, for example, this is set to one of the supply valves 12, 22 that cannot be closed and optionally If the second barrier system is unsuccessful in reducing the output of the first compressor 100, then the pressure at the first compressor outlet 105 is the first pressure of the pressure relief valve 250. The pressure continues to rise until the set pressure is reached, at which point the pressure relief valve 250 is opened, and at least a portion of the compressed discharge stream 150 is passed through the flare system 300 as a continuous compressed stream 160 and any No further pressure increase is expected.

  The advantages of the methods and apparatus disclosed herein may be illustrated with reference to an LNG export facility. The size of the LNG export facility flare system is determined by the relief load that must be addressed during the blocked outlet of the precooled compressor. If the relief load due to this case can be reduced by about 50%, then the other relief load case will dominate the size of the flare system. In some situations, this allows a reduction in flare height from about 180m to 120m, indicating a large size and weight reduction.

  In certain situations where space is limited, such as offshore LNG plants, this represents a significant cost savings for offshore ships or offshore platform structures.

  In preferred embodiments, the methods and apparatus disclosed herein are particularly suitable for installation on a floating ship, offshore platform or caisson. A floating ship generally has at least a hull and can be any movable or moored ship, usually in the form of a ship such as a “tanker”.

  Such a floating ship can be of any size but is usually elongated. The dimensions of a floating ship are not limited at sea, but building and maintenance equipment for floating ships may limit such dimensions. Thus, in one embodiment disclosed herein, a floating ship or offshore platform is shorter than 600m, such as 500m long, so that it can be accommodated in existing shipbuilding and maintenance facilities, It is a beam shorter than 100 m, such as 80 m.

  The offshore platform can also be movable but can generally be installed more permanently than a floating ship. The offshore platform can also be suspended and can have any suitable dimensions.

  It will be apparent how the concept illustrated in FIG. 1 can be extended to other embodiments in which there are two or more compressor feed streams. In preferred embodiments, the methods and apparatus disclosed herein can be applied to refrigerant compressors having four compressor feed streams.

  FIG. 2 shows an embodiment in which the first compressor 100 is provided with four compressor feed streams 10, 20, 30, 40. The mechanism shown in FIG. 2 employs a simplified refrigerant circuit such as the propane refrigerant precooling, propane precooling stage of the mixed refrigerant main cooling system (C3MR) disclosed in US Pat. No. 4,404,008. To express.

  The first compressor 100 includes a first compressor feed stream 10 and a second compressor feed stream 20 at a first inlet 18, a second inlet 28, a third inlet 38, and a fourth inlet 48, respectively. It can be a refrigerant compressor supplied by a third compressor supply stream 30 and a fourth compressor supply stream 40. The first compressor 100 supplies a compressed discharge flow 150 as a refrigerant discharge flow compressed at the outlet 105. For the sake of simplicity, FIG. 2 does not show any recycle flow.

  In this embodiment, the method disclosed herein comprises (a) a first compressor feed stream 10 having a first compressor feed valve 12 to a first inlet 18 of the first compressor 100. Passing a second compressor feed stream 20 having a second compressor feed valve 22 to a second inlet 28 of the first compressor 100, and a second of the first compressor 100. Passing a third compressor feed stream 30 having a third compressor feed flow valve 32 to the third inlet 38 and a fourth compressor feed stream to the fourth inlet 48 of the first compressor 100. Passing a fourth compressor feed stream 40 having a valve 42.

  After compression, the compressed refrigerant discharge stream 150 may be passed through one or more cooling devices, valves 350, 550, accumulator 500, and / or heat exchanger 600 that may generate a closed outlet event. .

  FIG. 2 shows a compressed discharge stream 150 passing through a discharge isolation valve 350 to provide a controlled compressed refrigerant stream 360. If the discharge isolation valve 350 fails to operate in the closed position, a compressor closed outlet event will occur.

  The controlled compressed refrigerant stream 360 may then be cooled with one or more cooling devices 400, such as an air or water cooler, to provide a cooled refrigerant stream 410. The cooled refrigerant stream 410 can be used to directly cool the stream 620, such as a hydrocarbon stream, or is a stream derived from the cooled refrigerant stream 410 that can be finally cooled. As such, it can be further processed before the cooling step. The cooled refrigerant stream is preferably at least partially condensed, more preferably inherently fully condensed, whereby at least a portion of the condensed refrigerant is evaporated to stream 620, Thereby, heat is removed from stream 620.

  Poor cooling in one of the cooling devices 400 results in a loss of condensation capacity and an increase in the pressure of the compressed discharge stream 150 at the compressor outlet 105. Such poor cooling can occur if the cooling flow to the cooling device 400, such as a cooling water flow, does not work well. This can cause a blocked exit event.

  In addition, also, the accumulation of inert material in any cooling device 400, such as in a condenser, can result in a blocked exit event. Such inert material may be generated by tube breaks in the heat exchanger 600, such as a coiled heat exchanger in fluid communication with the first compressor 100, for example.

  The cooled refrigerant stream 410 can be passed to an accumulator 500 that can supply an accumulator discharge stream 510. Accumulator discharge stream 510 may be passed through accumulator discharge isolation valve 550 to provide a controlled accumulator discharge stream 560. If the accumulator discharge isolation valve 550 becomes inoperative in the closed position, a closed outlet event can occur.

  The controlled accumulator discharge stream 560 can be passed to one or more heat exchangers 600. Where there are more than one heat exchanger 600, such heat exchangers can be arranged in series or in parallel, for example after expansion if the heat exchanger 600 is at different pressures. It can be supplied by a flow obtained from a controlled accumulator discharge stream 510. In the propane precooling phase of the C3MR process, four heat exchangers 600 are arranged in series, each operating at a different pressure to supply four compressor feed streams 10, 20, 30, 40. FIG. 2 shows only a single heat exchanger 600 for the sake of brevity.

  The controlled accumulator discharge stream 560 provides a hydrocarbon stream 620 to provide a cooled hydrocarbon stream 630 and / or a cooled refrigerant stream (not shown) and a heated refrigerant stream 610, and Heat may be exchanged with respect to other refrigerant streams (not shown) in the heat exchanger 600. The heated refrigerant stream 610 is returned to the first compressor 100 as a compressed first supply stream 10, second supply stream 20, third supply stream 30, or fourth supply stream 40. Can be further processed.

  The methods and apparatus disclosed herein allow a cooled hydrocarbon stream 630 to be liquefied, for example, a cooled natural gas stream, such as a precooled natural gas stream at a temperature of −35 ° C., or partially or completely liquefied. It is preferably used in an LNG plant so that it can be a natural gas stream. A cooled refrigerant stream, such as a mixed refrigerant stream, can also be supplied by one or more heat exchangers 600.

Natural gas consists mostly of methane. In addition to methane, natural gas is typically carbon dioxide, sulfur, hydrogen sulfide and other sulfur compounds, nitrogen, helium, water, other non-hydrocarbon acid gases, ethane, propane, butane, C ₅ + hydrocarbons and Includes some heavy hydrocarbons and impurities, including but not limited to aromatic hydrocarbons. These and any other common or known heavy hydrocarbons and impurities interfere with or interfere with the commonly known methods of liquefying methane, particularly the most effective methods of liquefying methane. The best known or proposed method of liquefying hydrocarbons, in particular natural gas, reduces as much as possible the level of heavy hydrocarbons and impurities prior to the liquefaction process. Based on.

  Hydrocarbons that are heavier than methane and usually ethane are usually condensed and recovered as natural gas liquids (NGLs) from natural gas streams. Methane is usually separated from NGLs in a high-pressure scrub column so that the NGLs produce valuable hydrocarbon products as vapor products themselves or as components of refrigerants for use in liquefaction, for example. And then fractionally distilled in several dedicated distillation columns.

  If a blocked outlet event occurs for the first compressor 100, the first indicator of the blocked outlet event is detected by the first monitoring device P1. For example, a level of pressure representative of a blocked outlet event is detected by a first pressure sensor P 1 in communication with the compressed refrigerant discharge stream 150. The first barrier system then directs closing of the first compressor supply valve 12, the second compressor supply valve 22, the third compressor supply valve 32, and the fourth compressor supply valve 42. .

  Thus, in the method of the embodiment of FIG. 2, step (d) includes the first compressor supply valve 12, if a first indicator of a closed outlet event of the first compressor 100 is detected, Instructing the closure of the second compressor supply valve 22, the third compressor supply valve 32, and the fourth compressor supply valve 42.

  Five primary safety standards may be applicable to the disclosed refrigeration system, where any of the four supply valves 12, 22, 32, 42 can be closed, one, two, three, Or 4 cannot be closed. Which safety criteria should be selected depends on the probability that these scenarios will occur.

  If the probability that one or more of the supply valves remains open is low enough to be acceptable, then in this case the first safety criterion can be set to zero valves that cannot be closed. The device is provided without a pressure relief valve 250 or flare system 300.

  If the probability that two or more of the supply valves remain open is low enough to be acceptable, but the probability that one of the supply valves remains open is unacceptably high, then One safety criterion can be set for a single supply valve that cannot be closed, and the flare system 300 is dimensioned to accept the flow generated by the compressor supply flow having the maximum flow rate.

  If the probability that three or more of the supply valves remain open is low enough to be acceptable, in this case, the first safety criterion can be set to two supply valves that cannot be closed. The flare system 300 is sized to accept the flow generated by two compressor feed streams having two maximum flow rates. Such a flare system 300 is larger than that of the previous paragraph embodiment, but handles the flow generated by the three or four compressor refrigerant feed streams 10, 20, 30 having the maximum flow rate. Obviously, it is even smaller than a flare system made to a precise size.

  If the probability that all four of the supply valves remain open is acceptably low, then the first safety criterion can be set for three supply valves that cannot be closed. The flare system 300 is sized to accept a flow generated by three compressor feed streams having three maximum flow rates. Such a flare system 300 is larger than that of the previous paragraph embodiment, but sized to handle the flow generated by the four compressor refrigerant feed streams 10, 20, 30, 40. Obviously it is even smaller than the flare system.

  Alternatively, if the probability that all four of the supply valves cannot be closed is unacceptably high, in this case, the first safety criterion may be set for all four supply valves that cannot be closed. The flare system 300 can be dimensioned to handle the entire stream with four compressor feed streams.

  Should any of the four supply valves 12, 22, 32, 42 fail to close under the direction of the first barrier system, the pressure at the outlet 105 of the refrigerant compressor 100 will continue to rise. To do. If a second barrier system is present for a second indicator that is selected to occur after the first indicator, then a second indicator of an occluded exit event is detected. If the second monitoring device P2 is a pressure sensor in communication with the compressed refrigerant discharge stream 150, in this case this is set to occur when a pressure higher than that of the first indicator is reached. Will be.

  FIG. 2 shows a steam turbine 200 b that is powered by a high pressure steam flow 240 that passes through a control valve 220 and a trip valve 230. Upon detecting an exit event occluded by the second barrier system, a third indication signal may be sent from the second controller XC2 to close the control valve 220 and trip valve 230. Should any of these valves close, the high pressure steam flow 240 is prevented from reaching the steam turbine 200b and the turbine is shut down, thereby shutting down the first refrigerant compressor 100.

  In other embodiments, the steam turbine 200b may be stopped by letting off the cooling load of the steam condenser 240 of the steam turbine 200b, thereby reducing the output to the first refrigerant compressor 100.

  If the second barrier system is successful, any further increase in pressure at the outlet 105 of the first refrigerant compressor 100 is prevented. Opening of the pressure relief valve 250 can be avoided so as not to cause any flaring of the inventory of the first compressor 100 and associated circuitry.

  If the first safety criteria is still met, but the first and second barrier systems are unsuccessful, then the pressure relief valve 230 opens when the set point pressure is reached, and the refrigerant supply Passing compressed refrigerant equal to the flow from streams 10, 20, 30, 40, supply valves 12, 22, 32, 42 remain open to flare system 300.

  Those skilled in the art will appreciate that the present invention may be implemented in many different ways without departing from the scope of the appended claims. For example, it will be apparent that the present invention can be utilized in any compressor system, not just the disclosed refrigerant circuit. Furthermore, while embodiments that utilize two and four compressor feed streams have been described in detail, the present invention can also be applied to any compressor having one or more compressor feed streams.

Claims (15)

A method of operating a compressor to reduce a relief load during a blocked outlet event, comprising:
(A) passing one or more compressor feed streams to one or more inlets of the first compressor, each compressor feed stream passing through a compressor feed valve;
(B) compressing one or more compressor feed streams with a first compressor to provide a compressed discharge stream at an outlet of the first compressor;
(C) monitoring a first indicator of a clogged outlet event of the first compressor;
And (d) detecting at least a first indicator of a closed first outlet event of the first compressor, indicating closing of the compressor supply valve. In step (a), there are n compressor feed streams that pass through n compressor feed valves, where n is an integer greater than or equal to 1,
In step (c), a first monitoring device monitors a first indicator of a closed first outlet event of the first compressor, and (e) m of the compressor supply valves are The method of claim 1, comprising providing a first safety criterion that cannot be closed in d), wherein m is an integer ranging from 0 to n. (F) providing a pressure relief valve in fluid communication with the compressed discharge flow, wherein the pressure relief valve is set to open at a first set pressure, Further comprising the step of reaching after the first indicator of the blocked exit event;
The pressure relief valve is connected to a flare system;
One or both of the pressure relief valve and the flare system are dimensioned to receive at least the relief flow generated by the first safety criteria, in which m of the compressor supply valves 3. The method of claim 2, wherein cannot be closed in step (d) and m is an integer in the range of 1 to n.   Step (a) passing a first compressor feed stream having a first compressor feed valve to a first inlet of the first compressor; and a second having a second compressor feed valve And passing the compressor feed stream to a second inlet of the first compressor. (G) driving the first compressor with the first driving device;
(H) monitoring the second index of the first compressor (blocked outlet event by the second monitoring device);
And (i) instructing a reduction in the compression output of the first compressor if a second indicator of a blocked outlet event of the first compressor is detected. The method as described in any one of.   One or more of the group wherein reducing the compression output of the first compressor includes reducing the speed of the first drive and reducing the supply of output to the first drive. The method according to claim 5, realized by:   The first drive is a steam turbine, and the reduction of the compression output of the steam turbine reduces the flow of steam to the turbine and releases the cooling load of the steam condenser of the steam turbine. 7. A method according to claim 5 or 6, realized by one or more of them.   8. A method according to any one of claims 5 to 7, wherein the first set pressure is reached after reaching the first and second indicators of a blocked outlet event of the first compressor. (I) the first index and the second index are the same, or
(Ii) the first index is selected such that it occurs before the second index, or
9. A method according to any one of claims 5 to 8, wherein (iii) the second index is selected such that it occurs before the first index.   The indication of the closed outlet event of the first compressor is the selected discharge pressure of the compressed discharge stream, the selected discharge temperature of the compressed discharge stream, the selected output of the first compressor, The selected one or more of the groups comprising a selected suction pressure of the one or more compressor feed streams and a selected suction temperature of the one or more compressor feed streams. The method according to any one of 1 to 9. The first compressor is a refrigerant compressor, the two or more compressor supply streams are refrigerant supply streams, the compressed discharge stream is a compressed refrigerant discharge stream, and (j) cooling Cooling the flow resulting from the compressed refrigerant discharge stream to provide a conditioned refrigerant stream;
(K) heat exchanging the cooled refrigerant stream or the resulting stream to a hydrocarbon stream or a further refrigerant stream to provide a cooled hydrocarbon stream. The method according to any one of the above.   The method of claim 11, wherein the hydrocarbon stream is a natural gas stream and the cooled hydrocarbon stream is a cooled natural gas stream, such as an at least partially liquefied natural gas stream. An apparatus for reducing a relief load during a compressor plugged outlet event,
A first compression having an outlet for a compressed discharge stream and one or more inlets for one or more compressor feed streams, each compressor feed stream passing through a compressor feed valve Machine,
A first controller is in communication with the first device to provide a first indication of a first compressor blocked outlet event, and a first controller is connected to the first compressor blocked outlet event. An apparatus comprising at least a first controller in further communication with each compressor supply valve so as to transmit a first signal to close each compressor supply valve upon detecting an index of one. There are n compressor feed streams that pass through n compressor feed valves, n is an integer greater than or equal to 1,
A pressure relief valve in fluid communication with a compressed discharge flow, dimensioned to open at a first set pressure, which is a first indicator of a closed outlet event of a first compressor A pressure relief valve reached after
A flare system in fluid communication with the pressure relief valve, wherein one or both of the pressure relief valve and the flare system are dimensioned to at least receive the relief flow generated by the first safety criterion; 14. The apparatus of claim 13, wherein m of the compressor supply valves cannot further be closed in step (d), and m further comprises a flare system in the range of 1 to n. . A first drive device mechanically connected to the first compressor to drive the first compressor;
The second controller transmits a third signal to reduce the compression output of the first compressor upon detection of a second indicator of a blocked outlet event of the first compressor; 15. The apparatus of claim 13 or 14, further comprising a second controller in communication with a second apparatus for providing a second indication of a blocked outlet event of the first compressor.

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