Integrated bypass cooling on turbo compressors with two or more process stages
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- COVESTRO DEUTSCHLAND AG
- Filing Date
- 2024-08-07
- Publication Date
- 2026-06-17
Smart Images
Figure EP2024072356_20022025_PF_FP_ABST
Abstract
Description
[0001] “Integrated bypass cooling on turbo compressors with two or more process stages”
[0002] The invention relates to the compression of process gases, in particular with turbocompressors, and the control of the compressors used therein by regulating the gas flow before it is introduced into a compressor stage using bypasses. This control is achieved by the compression method according to the invention and by a device with a special bypass circuit.
[0003] Compressors play an important supporting role in the industrial production of gases. For example, a compressor extracts gas from a gas source for compression and delivers this compressed gas to a gas consumer. As the gas is introduced into the compressor, the pumping action of the compressor creates suction; therefore, the side of the compressor with the gas supply is also called the suction side of the compressor.
[0004] To use compressors reliably in a process, the compression achieved by the individual compressor stages must be maintained within a specific pressure range. In particular, the compressor must be controlled in such a way that it can continuously deliver the gas flow requested by a downstream consumer from the gas source at a specific pressure and at the requested flow rate. The compressor control system must be able to respond variably to this requested flow rate.
[0005] Furthermore, especially in turbo compressors, the compressor control system is also responsible for protecting the compressor stages. The compressor stages are operated with a surge limit control, which ensures the flow through the compressor stage, regardless of the gas flow rate supplied through the supply line, so that the minimum permissible flow (i.e., the surge limit) is never exceeded. This phenomenon, known as surge, leads to vibrations in the compressor stage, destroys the turbo compressor, and must therefore be avoided.
[0006] State-of-the-art surge control involves recirculating a portion of the compressed gas from a compressor stage back to the compressor stage via a bypass. When using multiple compressor stages in series, each compressor stage has its own surge limit. In this case, a recirculation from the last compressor stage to the first compressor stage is typically provided to protect all stages simultaneously.
[0007] This state of the art has two disadvantages:
[0008] Firstly, the recirculation cannot be individually adjusted to the individual compressor stages, so the bypass is larger than necessary.
[0009] Secondly, the portion of the gas stream heated by compression from the last compressor stage intended for recirculation must be cooled to prevent it from entering the first stage hot and resulting in an unacceptably high temperature at its outlet. If the recirculated, compressed gas has to be cooled to a temperature close to its dew point, there is a risk that the dew point will be accidentally exceeded, and the resulting droplets will be carried with the gas stream into the first compressor stage, causing erosion damage.
[0010] Therefore, it is an object of the invention that the device can be used to better match the pumping protection to the individual compressor stages compared to the prior art.
[0011] Another task is to avoid condensation of the returned, compressed gas.
[0012] Another task is to provide a compressed, hot gas to be used for heat integration in process steps following compression.
[0013] It is also an object of the present invention to provide a method and a device for compressing gases, which has at least two surge limit controls and is capable of providing a gas flow in the required gas quantity on the suction side of the corresponding compressor stages.
[0014] During compression, the compressed gas heats up, so that in a multi-stage compression process it is cooled between the compressor stages. This increases the efficiency of the compression and prevents the compressor and gas from heating up beyond permissible temperature limits. Common heat exchanger types are used to cool the gas stream. Typically, a cooling device is provided after each compressor stage to cool the gas stream. This type of cooling is both energy-intensive and associated with the expenditure of resources, such as materials and costs, due to the provision and maintenance of the necessary cooling devices. The new process and the new device are intended to conserve resources and, in particular, to save energy, e.g. for cooling.
[0015] Furthermore, the decommissioning and maintenance of the compression device used should be simplified. During decommissioning, the supply and discharge lines of the compressor unit are closed. The gas present in the individual compressor stages has different pressures and now flows within the compressor unit into regions of lower pressure until a uniform pressure prevails in the compressor unit, the settle-out pressure. For maintenance work, after setting the settle-out pressure, the gas must be vented from the compressor unit and, if necessary, subsequently removed from the entire compression device using a purge gas.
[0016] It has been found that a modified method and a modified device for compressing gases solves the above-mentioned problems if the compression device contains at least two special bypasses in addition to at least two compressor stages.
[0017] With the present invention, unintentional condensation of the compressed gas downstream of the last compressor stage is avoided by the absence of a cooling device between the last compression stage and the branch intended for recirculation of the final compressed gas stream. As a result, the gas recirculated to the cooling device upstream of the suction side of the previous compressor stage no longer causes erosion of this compressor stage due to condensate droplets, even without the installation of liquid separators.
[0018] By eliminating the need for a cooling device between the final compression stage and the branch intended for recirculation of the final compressed gas stream, the gas volume that must be disposed of in the event of a shutdown of the device is also reduced. Likewise, the elimination of a cooling device results in fewer dead spaces in the device, which reduces the purging time when purging the device, if necessary. Furthermore, the elimination of a cooler and the inventive bypass circuitry have reduced the settle-out pressure.
[0019] A further advantage of the device according to the invention and the
[0020] The aim of the method is that the cooling devices used according to the invention
[0021] Dimensioning can be standardized. Compared to the prior art, due to the inventive switching of the bypasses, a smaller volume flow, which is adapted to the surge limits of the front compressor stages, is passed through the first cooling device than in the prior art. This means that the first cooling device can be slightly reduced in size. This volume flow also passes through the last cooling device and is only drawn off as a bypass downstream of it. In addition, the bypass from the last compressor stage is routed upstream of the last cooling device, i.e. the last cooling device is subjected to a larger volume flow than in the prior art. This slightly increases its dimensions, which enables uniform dimensioning of all cooling devices.
[0022] A first subject of the invention is a method for compressing gas from a gas stream, comprising at least the steps a) providing a gas stream containing at least one gaseous compound, b) introducing said gas stream via a feed line into a first compression stage, therein undergoing at least the following sub-steps: b1) introducing and compressing the introduced gas stream in a first compressor stage, b2) discharging the compressed gas stream, c) introducing the previously discharged compressed gas stream into a further compression stage, comprising at least one further compression step, wherein in each further compression step carried out, at least one cooling of the introduced gas stream takes place in a cooling device specific to this compression step and then a compression of the previously cooled gas stream takes place in a compressor stage specific to this compression step, with the proviso,that at least the following sub-steps are carried out: c1) introducing the discharged compressed gas stream into the dedicated cooling device, and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2) introducing at least a portion of the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3) discharging the compressed gas stream, c4) optionally repeating steps c1) to c3) to carry out at least one further compression step, wherein after completion of step c), a portion of the compressed gas stream discharged therefrom in a discharge line is branched off as a bypass gas stream into a bypass, returned to the last cooling device of step c) and combined with the gas stream intended for cooling and subsequent introduction into the final compressor stage of step c),wherein a flow control containing at least one valve controls the amount of gas to be returned via the bypass gas flow in the bypass and thereby controls the flow of the gas flow through the final compressor stage of step c).
[0023] It is preferred according to the invention if the gas stream discharged from the final compressor stage does not pass through a cooling device between the discharge of the compressed gas stream from the final compressor stage into the discharge line and the branching of the bypass gas stream provided for the removal of the bypass gas stream in the discharge line.
[0024] The gas stream provided in the process according to the invention undergoes a pressure increase through the individual compressor stages along the flow direction from its introduction into the compression stage and its compressor stages to the discharge of the compressed gas during the final compression stage. This flow direction of the gas stream thus corresponds to the pumping direction of the compressor stages. A "compressed gas stream" is understood to mean the portion of the gas stream that has already passed through at least one compressor stage.
[0025] A “bypass” is understood to mean a fluid connection in which at least a part of the compressed gas flow is passed past at least one compressor stage against the pumping direction of the compressor stages and is reunited with the gas flow.
[0026] According to the invention, a "fluid connection" is understood to mean a device component that connects system components to one another and through which a substance, which can be present in any aggregate state, can be transported from one system component to the next, for example, a supply line in the form of a pipe. A "bypass gas flow" is understood to mean a gas flow branched off from a compressed gas flow, which is recirculated through a bypass past at least one compressor stage against the pumping direction of the compressor stages and recombined at a position in the gas flow with a lower pressure than at the branch point.
[0027] According to the invention, each compressor stage is a turbo compressor stage.
[0028] The gas stream provided according to step a) contains at least one gaseous compound. The totality of all compounds present in the provided gas stream is referred to as the gas composition of the gas stream.
[0029] The process according to the invention is particularly advantageous in a further embodiment in which the gas composition of the gas stream provided according to step a) contains at least one halogen-containing gas selected from at least one gaseous compound of halogen, halogen, hydrogen, or mixtures thereof, for example, at least 90% by weight of halogen based on the total weight of the gas composition, as at least one gaseous compound. The use of an introduced gas stream containing at least chlorine gas, for example, at least 90% by weight of chlorine gas based on the total weight of the gas composition, as at least one gaseous compound has proven particularly preferred.
[0030] For compression, the gas stream provided in step a) of the process according to the invention is introduced via the supply line into a compressor unit containing at least two compressor stages—the first compressor stage and the final compressor stage. The compressor unit is a turbocompressor with multiple compressor stages.
[0031] In the method of the invention, the gas stream provided in step a) is first introduced in step b) via a feed line into a first compression, in which the gas stream is first introduced into a first compressor stage and compressed there, and the compressed gas stream is discharged again.
[0032] After this first compression according to step b), the method according to the invention provides that in step c) the compressed gas stream previously discharged from step b) is introduced into a further compression, comprising at least one further compression step, wherein in each further compression step carried out at least one cooling of the introduced gas stream takes place in a cooling device specific to this compression step and then a compression of the previously cooled gas stream takes place in a compressor stage specific to this compression step.
[0033] The gas stream is passed through each of the further compression steps of step c) in such a way that the gas stream compressed in a compression step of step c) is either the final compressed gas stream or is introduced into a subsequent compression step, with this subsequent compression step again using a separate cooling device and a separate compressor stage as previously defined. Several of these compression steps can be performed in step c).Thus, in step c) at least the following sub-steps are carried out: c1) introducing the discharged compressed gas stream into the dedicated cooling device, and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2) introducing at least a portion of the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3) discharging the compressed gas stream, c4) optionally repeating steps c1) to c3) to carry out at least one further compression step.
[0034] According to step c) of the method according to the invention, the sequence of steps c1) to c3) is run through at least once. The compressor stage that is run through last in step c), i.e., including possible repetitions of the sequence of steps c1) to c3), is also referred to as the final compressor stage. The cooling device that is run through last in step c), i.e., including possible repetitions of the sequence of steps c1) to c3), is also referred to as the final cooling device. Once step c) is completed, the compressed gas stream is discharged from the compressor unit via a discharge line.
[0035] According to step c4) of the method, steps c1) to c3) can optionally be repeated at least once with the compressed gas stream previously discharged from step c3). A particularly preferred embodiment of the method according to the invention provides that, according to step c) of the method, the sequence of steps c1) to c3) is carried out three times, and steps c1) to c3) according to step c4) are thus repeated twice, each time using a separate cooling device and in a separate compressor stage, with the compressed gas stream discharged from the previous step c3).
[0036] The cooling devices used in step c) of the process according to the invention for cooling the compressed gas stream cool the previously compressed gas stream before at least a portion of it is introduced into a further compression step. Said cooling devices are preferably heat exchangers. "At least a portion" in this context means that either the affected gas stream is introduced in its entirety or in part, depending on whether or not a bypass gas stream is explicitly removed prior to introduction.
[0037] Part of the cooling capacity of said cooling devices can be provided for the gas volume recirculated as a bypass gas flow without the use of additional energy if the gas has a positive Joule-Thomson coefficient. In this case, the gas cools during adiabatic expansion in the valve regulating the bypass gas flow.
[0038] For regulating the recirculated bypass gas flow, a surge limit valve is preferably used as the valve, with the valve more preferably being selected from a degree seat valve or a rotary cone valve. Within the scope of one embodiment of the method, the valve, which is more preferably designed as a pressure surge valve, degree seat valve, or rotary cone valve, has a passage with a diameter of at most 350 mm, particularly preferably at most 200 mm.
[0039] In a preferred embodiment, after at least one compressor stage of the process, a portion of the compressed, cooled gas stream is branched off as a bypass gas stream downstream of the cooling device of the subsequent compression step. It is returned to the gas stream upstream of the compressor stage and combined with this gas stream. The size of this bypass gas stream is regulated by a valve in which the bypass gas stream expands adiabatically and cools further if the gas has a positive Joule-Thomson coefficient.
[0040] If the source for the gas stream provided in step a) supplies a gas stream with a variable volume flow during the process (e.g., a gas production plant connected to provide the gas stream, such as a chlor-alkali electrolysis plant), in a preferred embodiment of the process, a portion of the compressed gas is returned via bypasses downstream of the cooling stages of the subsequent compression steps c) to the suction side of the upstream compressor stage, thereby restoring safe operation of the compressor stages of the compression device used. However, the operation of the bypasses requires additional cooling capacity from the cooling stages, which in turn results in higher energy consumption of the process.
[0041] A preferred embodiment of the method is therefore characterized in that, in order to regulate the gas flow after at least one sequence of steps c1) to c3) of step c), a portion of the gas flow from step c1 is branched off into a bypass, passed back past at least one compressor stage from at least one step selected from step b) or step c) and recombined with the gas flow, wherein in the bypass the size of the bypass gas flow is preferably regulated by at least one valve, wherein the bypass gas flow is further cooled by the adiabatic expansion at the valve if the gas has a positive Joule-Thomson coefficient.
[0042] A particularly preferred embodiment of the method is characterized in that, after the last cooling step c1) of step c) and before entering the final compressor stage of step c), a further bypass gas stream is branched off in a further bypass from the cooled gas stream, recirculated past the compressor stages of steps c) and b), and combined with the gas stream of step a) before its introduction into step b). A flow control system containing at least one further valve controls the amount of gas to be returned via the bypass gas stream in the further bypass and thus regulates the flow of the gas stream through the compressor stage of step b).
[0043] A preferred embodiment of the invention is one in which the bypass gas stream removed after the final compressor stage is recirculated upstream of the final cooling device of step c). It has been observed that the bypass gas stream can be precooled in the bypass by at least one adiabatic expansion taking place at the valve if the gas composition of the gas stream has a positive Joule-Thomson coefficient. Within the scope of a particularly preferred embodiment of the invention, the finally compressed gas stream does not pass through a cooling device between the discharge of the compressed gas stream from the final compressor stage into the discharge line and the branching of the bypass gas stream contained in the discharge line.
[0044] A particularly preferred embodiment of the method according to the invention provides that according to step c) of the method, the sequence of steps cl) to c3) is carried out three times, i.e. according to step c4), steps cl) to c3) are repeated twice in a respective separate cooling device and in a respective separate compressor stage with the compressed gas stream discharged from the previous step c3).
[0045] A particularly preferred embodiment of the method is thus characterized in that step c) is carried out by introducing the compressed gas stream discharged from step b) into an additional compression, therein undergoing at least the following sub-steps: c1) introducing the discharged compressed gas stream into the dedicated cooling device, and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2) introducing at least a portion of the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3) discharging the compressed gas stream, and again introducing at least a portion of the compressed and cooled gas stream discharged from step c3) into a further additional compression, therein undergoing at least the following steps: c1-1) introducing the discharged compressed gas stream into the dedicated cooling device,and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2-1) introducing the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3-1) discharging the compressed gas stream, and reintroducing at least a portion of the compressed and cooled gas stream discharged from step c3-1 into a further additional compression stage, therein undergoing at least the following steps: c1-2) introducing at least a portion of the discharged compressed gas stream into the dedicated cooling device, and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2-2) introducing the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3-2) discharging the compressed gas stream in a discharge line,wherein, after completion of step c), a portion of the compressed gas stream discharged therefrom in the discharge line is diverted into a bypass as a bypass gas stream, returned upstream of the cooling device of step c1-2), and combined with the gas stream intended for cooling and subsequent introduction into the final compressor stage of step c1). A flow control containing at least one valve controls the amount of gas to be returned via the bypass gas stream in the bypass and thereby regulates the flow of the gas stream through the final compressor stage of step c1. All of the aforementioned preferred embodiments of features of this particularly preferred embodiment also apply to this particularly preferred embodiment, mutatis mutandis, as preferred embodiments of these features.
[0046] The process according to the invention, as well as the further subject matters of the invention described below, can be combined, within the scope of a further preferred embodiment, with a liquefaction of substances that are gaseous under standard conditions. In this case, said gaseous substances are preferably liquefied for purification. For this purpose, a gas (in particular compressed gas from the compressed gas stream discharged from the final compressor stage of the process according to the invention into the discharge line) is liquefied and stored in a buffer tank under pressure (in particular at a relative pressure based on atmospheric pressure (overpressure) in the range of 2.5 to 13 bar). If the liquefied gas is to be removed from the buffer tank again, at least a portion of the liquefied gas is usually led out of the buffer tank and converted into a gas stream in an evaporator with the addition of heat.This gas stream is advantageously fed into a preheating device for further transport, where it is heated, particularly superheated, by additional heat input. For this heat input, the heat of the compressed gas stream discharged from the final compressor stage into the discharge line can be used for heat integration. In this embodiment of the method according to the invention, this heat integration step takes place after the bypass gas stream is diverted from the discharge line according to the invention.
[0047] If gas, preferably gas from the gas composition of said finally compressed gas stream, is introduced and / or stored in liquefied form in a buffer tank, it has proven particularly preferred within the scope of the embodiment of the method according to the invention if a liquefied gas taken from a buffer tank is fed to a preheating device after the evaporation step as the gas stream to be heated, and in this preheating device, the heat of the gas stream discharged from the final compressor unit is used as a heat source for heating, in particular superheating, said gas stream to be heated. In this case, no material mixing of the gas streams involved takes place.Advantageously, the compressed gas stream discharged from the final compressor stage into the discharge line, heated by compression, can therefore be used for heat integration as a heat source for a subsequent process step, in particular for heating a gas, in particular a gas (preferably a halogen gas) with a relative pressure relative to atmospheric pressure (overpressure) in the range of 2.5 to 13 bar. Within the scope of a preferred embodiment of the invention, the compressed gas stream discharged from the final compressor stage of step c) and located in the discharge line is fed, after the bypass gas stream has been branched off, to a device for heating a further gas stream (in particular a further halogen gas stream) as a heat source. The pressure of the gas stream to be heated is preferably within the aforementioned preferred pressure range.
[0048] The further gas stream to be heated is, of course, different from the compressed gas stream resulting from the final compression, particularly in terms of temperature and pressure.
[0049] The further gas stream to be heated in the preheating device further preferably contains, in all the aforementioned embodiments, at least 90% by weight of halogen, in particular at least 90% by weight of chlorine gas.
[0050] Within the scope of a further preferred embodiment of the invention, the compressed gas stream discharged from the final compressor stage of step c) into the discharge line is introduced into a flow path of at least one preheating device for a further gas stream behind the branching off of the bypass gas stream and is led out again after heat has been released, and the further gas stream is introduced into a further separate flow path of the same preheating device for heating, wherein said further gas stream is heated by heat exchange with the compressed gas stream of the final compressor stage (F) in the preheating device and is led out of the preheating device as a heated gas stream.
[0051] Preferably, the pressure of the further gas stream before introduction into the preheating device is in the aforementioned preferred pressure range.
[0052] If the gas to be heated in the preheater is previously drawn from a buffer tank as a liquid (particularly at a relative pressure relative to atmospheric pressure (gauge pressure) in the range of 2.5 to 13 bar), this liquefied gas must first be vaporized, thereby obtaining the additional gas stream intended for heating described above. This additional gas stream is introduced into the preheater for this purpose.
[0053] To evaporate the liquefied gas, in particular the chlorine, from the buffer vessel, the compressed gas stream emerging from the preheating device is preferably used as a heat source. For this purpose, it is preferred if the compressed gas stream discharged from the preheating device is introduced as a heat source into a flow path of an evaporation device, cooled by releasing heat, at least partially liquefied, and then discharged again, and a liquefied gas is withdrawn from a buffer vessel and introduced into another, different flow path of the evaporation device, wherein said liquefied gas is evaporated by heat exchange with the compressed gas stream of the final compressor stage in the evaporation device and discharged from the preheating device as another gas stream. In this process, no material mixing of the streams involved takes place.
[0054] If a liquefied gas, in particular chlorine, is evaporated at a relative pressure relative to atmospheric pressure (overpressure) in the range of 2.5 to 13 bar, the evaporated gas, in particular chlorine gas, generally exits the evaporation device at the dew point and is therefore introduced into the preheating device for heating, in particular superheating, within the scope of the aforementioned preferred embodiment of the invention.
[0055] The gas stream heated, in particular superheated, in the preheating device is delivered to a consumer via a pipeline, for example, after exiting the preheating device. Due to its heating, in particular superheating, the risk of condensation of the gas, in particular of the chlorine, in the pipeline to the consumer is significantly reduced. The method according to the invention can be excellently carried out in a device for compressing gas from a gas stream designed for this purpose. A further subject of the invention is therefore a device for compressing gas from a gas stream, comprising at least one supply line for a gas stream containing at least one gaseous compound to a compressor unit, as well as at least one discharge line for the compressed gas stream from the compressor unit, a compressor unit comprising at least a first compressor stage and a final compressor stage,wherein the supply line is in fluid communication with the gas inlet of the first compressor stage and the gas outlet of the first compressor stage is in fluid communication with the gas inlet of a final cooling device, as well as the gas outlet of the final cooling device is in fluid communication with the gas inlet of the final compressor stage, and the discharge line is in fluid communication with the gas outlet of the final compressor stage, at least one first bypass which connects the discharge line to the fluid connection located between the last cooling device and the compressor stage immediately preceding it, wherein the gas quantity guided in the bypass gas flow can be controlled by means of a first flow control located in the first bypass and containing at least one valve, and thereby the flow of the gas flow through the final compressor stage can be regulated, at least one second bypass provided with a second flow control,which connects the fluid connection between the last cooling device and the final compressor stage with the supply line.
[0056] As is necessary for the embodiments of the method according to the invention with at least one repetition of steps c1) to c3), in a preferred embodiment of the device, said compressor unit contains, for each intended repetition of said steps, a further compressor stage which is integrated into the device together with a further cooling device.
[0057] Thus, a device is preferably suitable according to the invention in which the compressor unit (4) contains at least one further inserted compressor stage, with the proviso that for each further inserted compressor stage there is a separate cooling device connected upstream of the respective inserted compressor stage, with the proviso that the gas outlet of the first compressor stage is in fluid connection with the inlet of an additional, inserted cooling device instead of the fluid connection with the inlet of the last cooling device, the outlet of the inserted cooling device is in fluid connection with the inlet of the inserted compressor stage and the outlet of the inserted compressor stage is in fluid connection either with the inlet of at least one further additional combination of cooling device and compressor stage or with the inlet of the last cooling device.
[0058] Each repetition of steps c1) to c3) thus requires the insertion of an insert element. Each of these insert elements is inserted between the first compressor stage and the last cooling device, with each insert element containing a cooling device and a compressor stage.
[0059] The cooling device of the insert element is always located on the suction side of the compressor stage of the same insert element. This is ensured by the gas outlet of the cooling device being in fluid communication with the gas inlet of the compressor stage of the insert element. An example of such an insert element is illustrated in Fig. 4a. If several insert elements are used, they are first linked in series in such a way that the gas outlet of the compressor stage of one insert element is connected to the gas inlet of the cooling device of the next insert element. The gas inlet of the linked insert elements, as the gas inlet of a cooling device, is in fluid communication with the gas outlet of the first compressor stage, and the gas outlet of the linked insert elements, as the gas outlet of a compressor stage, is in fluid communication with the gas inlet of the last cooling device. This is shown as an example in Fig.3 is illustrated by the linked insert elements using the dashed line.
[0060] It is also possible within the scope of a further embodiment for at least one of the plug-in elements used to additionally contain a bypass provided with a flow control, wherein this bypass is removed after the outlet of the compressor stage of the plug-in element and returned before the inlet of the cooling device of the same plug-in element. Such a plug-in element with a bypass is illustrated as an example in Fig. 4b. A further possibility is for at least one of the plug-in elements used to additionally contain a bypass provided with a flow control, wherein this bypass is removed after the outlet of the cooling device of the plug-in element and returned before the inlet of the compressor stage of the preceding plug-in element.
[0061] It is advantageous according to the invention if, in a preferred embodiment, the device does not have any further cooling device after the gas outlet from the final compressor stage of the device.
[0062] Preferably, the compressor stages of the device are operated with a suction pressure control, since the suction pressure of the compressor stage is influenced by the amount of gas supplied through the supply line. For this purpose, the device preferably has a suction pressure control.
[0063] In general, devices in which each of the bypasses has a valve are preferred, allowing the gas flow rate in the affected bypass to be controlled by a control unit. The control is intended to provide a sufficient gas quantity for surge limit control of the compressor stage upstream of the bypass. Furthermore, an adiabatic expansion of the gas with cooling occurs at the valve if the gas has a positive Joule-Thomson coefficient.
[0064] Furthermore, in one embodiment of the device, the flow control valve can function as a bypass control in the sense of a safety valve, preventing a backflow of the gas through the entire compressor unit in the event of a complete failure of the gas supply in the supply line or a significant pressure difference between the compressed gas stream after completion of the final compression and the gas stream supplied in the supply line. Within the scope of this embodiment, the bypass has two valves installed in parallel, each with flow control, whereby both valves can be used for adiabatic expansion. At least one of the valves preferably has a passage diameter of at least 50 mm, preferably more than 200 mm; this one valve can also be used as a safety valve as described above.
[0065] As previously described for the implementation of the method according to the invention and its embodiments, preferred devices are characterized in that said cooling devices cool the gas stream according to the heat exchanger principle via a cooled medium as cooling.
[0066] In a very special embodiment of the device, the gas stream discharged from the device's outlet and compressed by the final compressor stage is no longer fed into a cooling device and cooled. As a result, this very special embodiment contains one fewer cooling device than the number of compressor stages.
[0067] For example, the described compressor unit can be used in conjunction with chlor-alkali electrolysis or oxidation of hydrogen chloride (Deacon process) to compress the resulting chlorine gas in such a way that it can be liquefied with common coolants in several cooling stages or in a liquefaction device designed as a flash cooler. If the liquefaction device for liquefying the compressed gas stream discharged from the final compressor stage is designed in such a way that liquid chlorine from a buffer tank is evaporated therein as the liquid to be heated in order to cool and liquefy the compressed gas stream, e.g. compressed chlorine gas, using the resulting cold, then compressed chlorine gas from the final compressor stage can advantageously be used as a heat source for evaporating the liquid chlorine gas originating from the buffer tank.For this purpose, at least two devices are preferably required: at least one device for evaporating the liquefied gas, in particular chlorine gas, and at least one preheating device for heating the gas stream resulting from evaporation. The compressed gas stream, in particular chlorine gas stream, located in the discharge line downstream of the branch of the first bypass from the final compressor stage serves as a heat source. It is first fed into the preheating device and then from the preheating device into the evaporation device. In the opposite direction, the liquefied gas is first fed from the buffer tank into the evaporation device, and the further gas stream obtained from it after evaporation is fed into the.
[0068] Preheating device.
[0069] Within the scope of this embodiment, the device according to the invention preferably additionally contains at least one preheating device as a heat exchanger with at least two flow paths, wherein at least one flow path has at least one inlet for compressed gas, which is in fluid connection with the discharge line (3) for the finally compressed gas flow from the compressor unit (4) downstream of the first bypass (6a), and at least one outlet for the compressed gas; and at least one further flow path has at least one inlet for a further gas flow, in particular chlorine gas, which is in fluid connection with a source for said further gas flow and has at least one outlet for the heated gas flow, in particular for heated chlorine gas.
[0070] Furthermore, a preferred embodiment of said compression device equipped with a preheating device additionally contains at least one evaporation device as a heat exchanger with at least two flow paths, wherein at least one flow path has at least one inlet for compressed gas, which is in fluid communication with the preheating device via the outlet for the compressed gas stream, and at least one outlet for the compressed, cooled and at least partially liquefied gas; and at least one further flow path has at least one inlet for a liquefied gas, in particular liquid chlorine, which is in fluid communication with a source for said liquefied gas, preferably with a buffer container for liquefied gas, particularly preferably for liquid chlorine, and has at least one outlet for vapor of said liquid, in particular for chlorine gas.
[0071] The subject matter of the device for compressing gas from a gas stream, as well as its previously described embodiments, are suitable for carrying out the inventive method of the first subject matter of the invention and are preferably used for this purpose. A further subject matter of the invention is therefore the use of a corresponding device for compressing gas from a gas stream for compressing a gas stream according to a method of the first subject matter of the invention. The invention is illustrated below by way of example without being limited thereto.
[0072] Example
[0073] Legend to the figures Fig. 1 to Fig. 5:
[0074] 1 first compressor stage (turbo compressor stage)
[0075] E compressor stage of a turbo compressor device inserted between the first and final compressor stage
[0076] El first inserted compressor stage (turbo compressor stage)
[0077] E2 second inserted compressor stage (turbo compressor stage)
[0078] F final compressor stage (turbo compressor stage)
[0079] 2 Supply line to the compressor unit 4 for a gas stream containing at least one gaseous compound
[0080] 3 Discharge from the compressor unit for the final compressed gas stream
[0081] 4 Compressor unit, containing 1, F, 7 and 8, and if marked E, El or E2
[0082] 5 Flow control, containing 9 and 10
[0083] 5a first flow control, containing 9 and 10
[0084] 5b second flow control, containing 9 and 10
[0085] 6 Bypass
[0086] 6a first bypass
[0087] 6b second bypass
[0088] 7 Drive unit for the rotation of the axis 8
[0089] 8 axis
[0090] 9 Control unit
[0091] 10 Valve
[0092] E inserted compressor stage
[0093] WA0E inserted cooling device
[0094] WA0E1 first inserted cooling device
[0095] WA0E2 second inserted cooling device
[0096] WA00F last cooling device
[0097] In Figures 1 to 5, a fluid connection between the individual compressor stages of the compressor unit, represented by a thick line, symbolizes the flow of the gas stream caused by the pumping action of the compressor stages, with the imposed flow direction from the suction side of the compressor unit to the discharge of the finally compressed gas from the compressor unit. This flow direction is indicated accordingly with arrowheads along the fluid connection and is highlighted again by an arrow at the beginning and end.
[0098] In Figures 1 to 5, fluid connections represented by a thin line correspond to bypasses in which the gas flow, due to pressure differences, flows opposite to the flow direction of the main gas flow imposed by the pumping action of the compressor stages during the compression process (bypass gas flow). This flow direction is indicated accordingly by arrowheads along the fluid connection.
[0099] Fig. 1 shows a prior art device for compressing gas from a gas stream, comprising at least one supply line 2 for a gas stream containing at least one gaseous compound to the compressor unit 4, as well as at least one discharge line 3 for the compressed gas stream from the compressor unit 4, a compressor unit 4 comprising at least a first compressor stage 1, two inserted compressor stages E and a final compressor stage F, wherein each compressor stage is followed by a separate cooling device and the gas outlet of each compressor stage is in fluid communication with the gas inlet of the corresponding cooling device and the gas outlet of the respective cooling device is in fluid communication with the gas inlet of the subsequent compressor stage, at least one bypass 6 provided with a flow control 5,which connects the outlet line located after the gas outlet of the last cooling device WA00F with the supply line 2.
[0100] The compressor unit 4 is a turbo compressor mechanically driven via an axle 8 by a drive unit 7, containing said compressor stages connected in series.
[0101] The bypass 6 has its own flow control 5 containing a valve 10 and a control unit 9.
[0102] Fig.2, however, shows an example of a device according to the invention for compressing gas from a gas stream, comprising at least one supply line 2 for a gas stream containing at least one gaseous compound to the compressor unit 4, as well as at least one discharge line 3 of the compressed gas stream from the compressor unit 4, a compressor unit 4, comprising at least a first compressor stage 1 and a final compressor stage F, wherein the supply line 2 is in fluid communication with the gas inlet of the first compressor stage 1 and the gas outlet of the first compressor stage 1 is in fluid communication with the gas inlet of a final cooling device WA00F, as well as the gas outlet of the last cooling device WA00F is in fluid communication with the gas inlet of the final compressor stage F, as well as the discharge line 3 is in fluid communication with the gas outlet of the final compressor stage F, at least one first bypass 6a, which connects the discharge line 3 to the fluid connection,which is located between the last cooling device WA00F and the compressor stage immediately preceding it, wherein the gas quantity guided in the bypass gas flow can be controlled by a first flow control 5a located in the first bypass 6a and containing at least one valve 10, and thereby the flow of the gas flow through the final compressor stage F can be regulated, at least one second bypass 6b provided with a second flow control 5b, which connects the fluid connection located between the last cooling device WA00F and the final compressor stage F to the supply line 2.
[0103] The compressor unit 4 is a turbo compressor mechanically driven via an axle 8 by a drive unit 7, containing said compressor stages.
[0104] Each bypass has its own flow control (here: 5a and 5b) containing a valve 10 and a control unit 9.
[0105] With the aid of the device in Fig. 2, a method according to the invention can be carried out in which no repetition according to step c4) is carried out. If at least one repetition according to step c4) of the method according to the invention is to be carried out, the device must be expanded by at least one insertion of an insertion element illustrated in Fig. 4a or Fig. 4b as a combination of an inserted cooling device WAOE and a compressor stage E inserted on the axis 8 between compressor stage 1 and compressor stage F. The compressed gas flow led out of compressor stage 1 is first led into the inserted cooling device WAOE and then into the inserted compressor stage E. The gas flow led out of compressor stage E can then either be fed into a further insertion element according to Fig. 4a or Fig.4b of process step c4) or finally into the last cooling device WA00F of step c). - TI -.
[0106] Fig. 5 illustrates an example of a device according to the invention for compressing gas from a gas stream, which is configured based on the device according to the invention in Fig. 2, with the difference that between the first compressor stage 1 and the last cooling device WAOOF there are two inserted compressor stages E, E1 and E2, positioned upstream of each of which is an inserted cooling device WAOE, for E1 the inserted cooling device WA0E1 and for E2 the inserted cooling device WA0E2. The insertion of the corresponding device components, starting from the device in Fig. 2, as well as the guidance of the compressed gas stream along the imposed flow direction of the compressed gas stream, which must be ensured during this insertion, is illustrated in Fig. 3. The device according to Fig.3 The dashed components of the device and the dashed fluid connections apply to the case of insertion, resulting in the device of Fig. 5. Without the dashed components of the device, the flow of the compressed gas would have to be guided along the dash-dot line, resulting in the device of Fig. 2.
[0107] From Fig. 3, it can be seen that the insertions do not change the routing of the respective bypasses included in Fig. 2. It is possible to introduce an additional bypass by inserting an insert element according to Fig. 4b. At least a portion of the compressed gas flow discharged from compressor stage E is extracted through the bypass and returned to the cooling device WAOE of the same insert element. A flow control 5 comprising at least one valve 10 and a control unit 9 regulates the bypass gas flow conducted in this bypass.
Claims
P a t e n t a n s p r ü c h e 1. A method for compressing gas from a gas stream in a suitable device, comprising at least the steps in the order of a) providing a gas stream containing at least one gaseous compound, b) introducing said gas stream via a feed line (2) into a first compression stage, therein undergoing at least the following sub-steps: b1) introducing and compressing the introduced gas stream in a first compressor stage (1), b2) discharging the compressed gas stream, c) introducing the previously discharged compressed gas stream into a further compression stage, comprising at least one further compression step, wherein in each further compression step carried out, at least one cooling of the introduced gas stream takes place in a cooling device dedicated to this compression step, and thereafter a compression of the previously cooled gas stream takes place in a compressor stage dedicated to this compression step,with the proviso that at least the following sub-steps are carried out: c1) introducing the discharged compressed gas stream into the dedicated cooling device, and cooling the compressed gas stream introduced for cooling, and discharging the cooled gas stream, c2) introducing at least a portion of the discharged cooled gas stream into the dedicated compressor stage and compressing it therein, c3) discharging the compressed gas stream, c4) optionally repeating steps c1) to c3) to carry out at least one further compression step, characterized in that after completion of step c), a portion of the compressed gas stream discharged therefrom in a discharge line (3) is branched off as a bypass gas stream (6a) into a bypass, returned upstream of the last cooling device of step c) (WA00F) and mixed with the gas stream for cooling and subsequent introduction into, the final compressor stage (F) of step c) is combined, wherein a flow control (5a) containing at least one valve (10) controls the amount of gas to be returned via the bypass gas flow in the bypass (6a) and in the process regulates the flow of the gas flow through the final compressor stage (F) of step c).
2. Method according to claim 1, characterized in that from the cooled gas stream after the last cooling step of step c) and before entering the final compressor stage (F) of step c), a further bypass gas stream is branched off in a further bypass (6b), returned past the compressor stages of steps c) and b), and combined with the gas stream of step a) before its introduction into step b), wherein a flow control (5b) containing at least one further valve (10) controls the amount of gas to be returned via the bypass gas stream in the further bypass (6b) and in the process regulates the flow of the gas stream through the compressor stage of step b).
3. Method according to one of claims 1 or 2, characterized in that at least one surge limit valve is located in the corresponding bypass as the valve (10).
4. Process according to one of the preceding claims, characterized in that in the gas composition of the gas stream provided according to step a) at least one halogen-containing gas selected from at least one gaseous compound of halogen, halogen hydrogen or mixtures thereof is contained as at least one gaseous compound.
5. The process according to any one of the preceding claims, characterized in that the gas composition of the gas stream provided according to step a) contains at least one halogen-containing gas selected from at least one gaseous compound of halogen, hydrogen halide or mixtures thereof, in particular at least 90% by weight of halogen based on the total weight of the gas composition, as at least one gaseous compound.
6. Method according to one of the preceding claims, characterized in that the compressed gas stream discharged from the final compressor stage of step c) into the discharge line is introduced behind the branching of the bypass gas stream into a flow path of at least one preheating device for a further gas stream and is led out again and into a further separate The further gas stream is introduced for heating purposes into the flow path of the same preheating device, wherein said further gas stream is heated by heat exchange with the compressed gas stream of the final compressor stage in the preheating device and is led out of the preheating device as a heated gas stream.
7. The method according to claim 6, characterized in that the compressed gas stream discharged from the preheating device is introduced as a heat source into a flow path of an evaporation device, is cooled by releasing heat and is at least partially liquefied and discharged again, and a liquefied gas is taken from a buffer container and introduced into a further, different flow path of the evaporation device, wherein said liquefied gas is evaporated by heat exchange with the compressed gas stream of the final compressor stage in the evaporation device and is led out of the preheating device as a further gas stream.
8. A device for compressing gas from a gas stream, comprising at least one supply line (2) for a gas stream containing at least one gaseous compound to a compressor unit (4), as well as at least one discharge line (3) for the compressed gas stream from said compressor unit (4), said compressor unit (4) comprising at least a first compressor stage (1) and a final compressor stage (F), wherein the supply line (2) is in fluid communication with the gas inlet of the first compressor stage (1) and the gas outlet of the first compressor stage (1) is in fluid communication with the gas inlet of a final cooling device (WA00F), as well as the gas outlet of the last cooling device (WA00F) is in fluid communication with the gas inlet of the final compressor stage (F), and the discharge line (3) is in fluid communication with the gas outlet of the final compressor stage (F), at least one first bypass (6a) connecting the discharge line (3) to the fluid connection,which is located between the last cooling device (WA00F) and the compressor stage immediately upstream thereof, wherein the gas quantity guided in the bypass gas flow can be controlled by means of a first flow control (5a) located in the first bypass (6a) and containing at least one valve (10), and thereby the flow of the gas flow through the final compressor stage (F) can be controlled, at least one second bypass (6b) provided with a second flow control (5b), said second bypass connecting the fluid connection located between the last cooling device (WA00F) and the final compressor stage (F) to the supply line (2).
9. Device according to claim 8, characterized in that the compressor unit (4) contains at least one further inserted compressor stage (El and / or E2), with the proviso that for each further inserted compressor stage (El and / or E2) there is a separate cooling device (WA0E1 and / or WA0E2) connected upstream of the respective inserted compressor stage, with the proviso that the gas outlet of the first compressor stage (1) is in fluid connection with the inlet of an additional, inserted cooling device (WA0E1) instead of the fluid connection with the inlet of the last cooling device (WA00F),the outlet of the inserted cooling device (WA0E1) is in fluid communication with the inlet of the inserted compressor stage (El) and the outlet of the inserted compressor stage (El) is in fluid communication either with the inlet of at least one further additional combination of cooling device (WA0E2) and compressor stage (E2) or with the inlet of the last cooling device (WA00F).
10. Device according to one of claims 8 or 9, characterized in that said cooling devices cool the gas stream according to the heat exchanger principle via a cooled medium as cooling.
11. Device according to one of claims 8 to 10, characterized in that said compressor unit (4) comprises at least one turbocompressor mechanically driven via an axis (8) containing said compressor stages.
12. Device according to one of claims 8 to 11, characterized in that it additionally contains at least one preheating device as a heat exchanger with at least two flow paths, wherein at least one flow path has at least one inlet for compressed gas, which is in fluid communication behind the first bypass (6a) with the discharge line (3) for the final compressed gas flow from the compressor unit (4), and at least one outlet for the compressed gas; and at least one further flow path has at least one inlet for a further gas stream, in particular chlorine gas, which is in fluid communication with a source of said further gas stream and has at least one outlet for the heated gas stream, in particular for heated chlorine gas.
13. Device according to claim 12, characterized in that it additionally contains at least one buffer container and at least one evaporation device as a heat exchanger with at least two flow paths, wherein at least one flow path has at least one inlet for compressed gas, which is in fluid connection with the preheating device via the outlet for the compressed gas stream, and at least one outlet for the compressed gas; and at least one further flow path has at least one inlet for a liquefied gas, in particular liquid chlorine, which is in fluid connection with a source of said liquefied gas, preferably with a buffer container for liquefied gas, particularly preferably for liquid chlorine, and has at least one outlet for vapor of said liquid, in particular for chlorine gas.
14. Use of a device according to one of claims 8 to 13 for compressing a gas stream according to a method according to one of claims 1 to 7.