Cycle gas chillers and liquefaction equipment

Abstract

The present invention relates to a cryogenic refrigerator (2) having a cycle circuit comprising a compression mechanism having at least three rotary compressors (4) arranged in parallel and attached to three rotating shafts, at least two of the rotating shafts being coupled to a turbine (10), at least one motor (12) for driving at least one of the rotating shafts (11), and at least two compressors (4) coupled in parallel to the turbine (10) each having a member (9) for measuring the flow rate passing through the compressor (4) and the compressor (4) The invention relates to a cryogenic refrigerator (2), wherein each turbine (10) is associated with and coupled to a respective member (14) for adjusting the flow rate entering the turbine (10), and each turbine (10) is equipped with a respective sensor (17) for measuring the rotational speed of the turbine (10) and a respective system (15, 16) for controlling the rotational speed of the turbine (10), and the refrigerator (1) is equipped with a control member (20) for measuring the speed and controlling the flow rate control member (14), the control member (20) being equipped with a microprocessor and configured to receive measured values ​​from the flow rate measuring member (9) and the sensor (17).

Description

Technical Field

[0001] The present invention relates to a cycle gas refrigerator and a liquefaction facility.

[0002] In particular, the present invention is a cycle gas refrigerator including a cycle circuit including a cycle gas including at least one of nitrogen, helium, and hydrogen. The cycle circuit is configured to supply a cycle fluid to a thermodynamic cycle that brings the cycle fluid to a predetermined cryogenic temperature at at least one end of the cycle circuit. The cycle circuit includes a mechanism for compressing the cycle fluid, a mechanism for cooling the cycle fluid, and a mechanism for expanding the cycle fluid. The mechanism for expanding the cycle fluid includes at least two turbines rotatably attached to respective rotating shafts. The compression mechanism includes at least three rotary compressors arranged in parallel with the cycle circuit and attached to three rotating shafts, respectively. At least two of the rotating shafts are each coupled to a turbine so as to recover the work of expansion of the cycle fluid to compress the cycle fluid, and relates to a cycle gas refrigerator.

Background Art

[0003] One important aspect of hydrogen and / or helium refrigerators / liquefiers is to minimize energy consumption. One way to reduce this consumption is to recover the expansion energy of the cycle gas and compress this cycle gas through a machine called a "turbo booster" (i.e., a "turbo compressor," i.e., a combination of a turbine and a compressor). See, for example, U.S. Patent Application Publication No. 2015 / 168057 A or International Publication No. 2009 / 130466 A pamphlet. The turbo compressor makes it possible to both reduce the consumption of electrical energy input to the cycle and reduce the size of the cycle compressor.

[0004] Turbo compressors can be positioned upstream or downstream of the cycle compressors depending on the process conditions. This arrangement is the most frequently seen in a cycle. In fact, this arrangement is the simplest for controlling the process because each compressor is independent of the others. This series connection configuration is made possible by operating conditions and suitable working fluids that promote high-efficiency compression.

[0005] The function of a turbo compressor includes adapting the parameters of the expanding fluid to the compressing fluid so that both functions are implemented with the greatest possible efficiency. The turbo compressor must also be able to operate through all configurations that the chiller / liquefier faces. The operating parameters of the turbo compressor can limit the possible turbine placement, potentially reducing process efficiency or complicating the process.

[0006] In the case of multiple turbo compressors connected in parallel, these compressors achieve the same compression ratio. A fluctuation in the output of one turbine then directly affects the other turbo compressors, and therefore the overall efficiency and operability of the refrigeration system. [Overview of the project] [Problems that the invention aims to solve]

[0007] One object of the present invention is to overcome all or some of the drawbacks of the prior art described above. [Means for solving the problem]

[0008] For this purpose, the refrigerator according to the present invention also comprises, in essence, according to the general definition in the above preamble, at least one motor for driving at least one rotating shaft supporting a turbine and a compressor, at least two parallel-connected compressors coupled to the turbine each associated with a member for measuring the flow rate passing through the compressor and a member for adjusting the flow rate entering the compressor, one or more upstream or downstream movable guide members such as "IGV", and at least two turbines coupled to the compressor each comprising a sensor for measuring the rotational speed of the turbine and a system for controlling the rotational speed of the turbine, and the refrigerator comprises an electronic control and command member comprising a microprocessor and configured to receive measured values ​​from the member for measuring the flow rate and the sensor for measuring the speed and to command the member for adjusting the flow rate.

[0009] According to the proposed solution, the chiller utilizes at least one motor-turbo compressor (instead of the turbo compressor described above) to bring about this active control between the parallel-coupled compressors by adjusting the power supplied to the motors. This control can be implemented by a variator that changes the rotational frequency of the one or more electric motors.

[0010] Adding one or more motors increases the capital cost of the chiller hardware, but allows for control of the motor's rotational frequency, improving the efficiency of turbine expansion and / or parallel compression, as well as the compression force. In other words, compared to prior art, it is possible to increase the outlet pressure or reduce the size of the cycle compressor compared to conventional turboboosters.

[0011] By providing at least one motor, it becomes possible to control the rotational speed of the corresponding impellers (compressor and turbine), and especially when several are installed in parallel, it becomes possible to stabilize the operation of one or more coupled compressor and turbine assemblies. In fact, in parallel arrangements, there is less disruption that destabilizes the assembly and causes it to operate suboptimally. This can even lead to one of the compressors operating in an unsafe operating region, such as the pumping region. This drawback is eliminated or mitigated by one or more motors. This also makes it possible to optimize the operating points of the machinery (compressor / turbine).

[0012] In addition, embodiments of the present invention may have one or more of the following features. - The compressors connected in parallel are identical, and the electronic control and command components are identical for all of the compressors connected in parallel, configured to apply set values ​​for the flow rate entering the compressor. - The electronic control and command components are configured to apply the same set value to the rotational speed of the turbine coupled to the compressor. - The components for adjusting the flow rate into the compressor include at least one of the following: one or more movable guide members, an upstream inlet guide vane "IGV", a variable vane diffuser downstream of the compressor impeller, and a system for bypassing the compressor. - The chiller has a component for adjusting the flow rate entering the compressor, which is shared by at least some of the compressors connected in parallel. - The system for controlling the rotational speed of the turbine comprises at least one of the following: an inlet guide vane "IGV", a throttle valve, and a system for bypassing the turbine. - The refrigerator comprises three or more drive motors configured to drive the three rotating shafts of three rotary compressors arranged in parallel in the cycle circuit. - The electronic control and command members are configured to manage the speed of one or more motors. - One or more motors are electric motors, and the electronic control and command members are configured to command the rotational speed of one or more motors to achieve the same compression ratio in each compressor.

[0013] The present invention also relates to equipment for liquefying a flow of supply gas, comprising a supply pipe configured to be connected to a source of supply gas to be liquefied, such as hydrogen, and a set of heat exchangers for exchanging heat with the flow of supply gas carried by the supply pipe, wherein the equipment comprises a chiller configured to exchange heat with the set of heat exchangers and cool the flow of supply gas, the chiller conforming to any one of the features described above or below.

[0014] The present invention may also relate to any alternative device or method having any combination of the features described above or below within the scope of application of the present invention.

[0015] Other specific features and advantages will become apparent by reading the following description provided with reference to the diagram.

[0016] The present invention will be better understood by reading the following description, which is provided purely as examples, and by referring to the accompanying drawings. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic diagram of a partial embodiment of the structure and operation of a liquefaction facility equipped with an exemplary refrigerator according to the present invention. [Figure 2] Figure 2 is a schematic diagram showing one embodiment of the operation of the electronic control and command components of a refrigerator. [Modes for carrying out the invention]

[0018] Throughout the drawing, the same reference numeral relates to the same element.

[0019] In the embodiments for carrying out the present invention, the following embodiments are illustrative. The description refers to one or more embodiments, which does not mean that the features are applicable only to a single embodiment. The individual features of different embodiments can also be combined and / or replaced to provide other embodiments.

[0020] The illustrated cycle gas refrigerator 2 includes a cycle circuit 3 containing a cycle gas including at least one of nitrogen, helium, and hydrogen.

[0021] The cycle circuit 3 is configured to supply a cycle fluid to a thermodynamic cycle that brings the cycle fluid to a predetermined cryogenic temperature at at least one end of the cycle circuit 3. As shown in FIG. 1, this cold heat generated can be utilized to cool a flow 18 of a supply gas such as hydrogen through, for example, a set of heat exchangers 19. The flow of the supply gas can be supplied to the first end of the supply pipe 18 by a supply source 19. The second end of the supply pipe may be connected to a storage unit that recovers the cooled (liquefied) supply gas.

[0022] In another modification (not shown), the cold heat generated can be used to liquefy the cycle gas itself, and this can be recovered.

[0023] The cycle circuit 3 preferably includes a mechanism 4 for compressing the cycle fluid, systems 5, 6, 7, 8 for cooling the cycle fluid, a mechanism 10 for expanding the cycle fluid, and a system for heating the cycle fluid, which are arranged in series in the cycle circuit 3.

[0024] The mechanism 10 for expanding the cycle fluid preferably includes at least two turbines 10 rotatably attached to respective rotating shafts 11, which are arranged in series in the cycle circuit 3.

[0025] The compression mechanism comprises at least three rotary compressors 4 arranged in parallel in the cycle circuit 3 and mounted on three rotating shafts, respectively. At least two of the rotary shafts of the compressors 4 are coupled to the turbine 10, respectively, to recover the work done by the expansion of the cycle fluid in order to compress the cycle fluid. Systems for cooling the cycle gas and systems for heating the cycle gas may comprise one or more heat exchangers, in particular one or more counterflow heat exchangers that exchange heat between the relatively low temperature and high temperature flows of the cycle.

[0026] In addition, the chiller 2 includes at least one motor 12 for driving at least one of the rotating shafts 11 that support the turbine 10 and the compressor 4. That is, at least one of the pairs of compressors (turbo compressors) coupled to the turbine is a motor-driven turbo compressor.

[0027] In addition, at least two parallel-connected compressors 4 coupled to the turbine 11 are each associated with a component 9 (e.g., a flow meter) for measuring the flow rate passing through the compressor 4 and a component 14 for adjusting the flow rate entering the compressor 4.

[0028] Each of the components 14 for adjusting the flow rate entering the compressor 4 is, for example, one or more upstream and / or downstream movable guide members such as "IGV" (inlet guide vane). In a modified example, or in combination, each of the components 14 for adjusting the flow rate entering the compressor 4 may be a bypass (a controlled deflection of the flow supplied to the compressor or compression stage).

[0029] In addition, each turbine 10 coupled to the compressor 4 preferably includes a sensor 17 for measuring the rotational speed of the turbine 10 and systems 15, 16 for controlling the rotational speed of the turbine 10.

[0030] The refrigerator 1 includes a microprocessor and an electronic control and command member 20 configured to receive measurements from a member 9 for measuring flow rate and a sensor 17 for measuring speed, and to command members 14, 16 and / or one or more motors 12 for adjusting the flow rate. See Figure 2.

[0031] This makes it possible to control the flow rate of the cycle gas in the parallel-connected compressors 4. This allows a set value for the flow rate to be applied to one of the compressors 4 and copied to the other compressors 4 connected in parallel (all compression stages can be composed of compressors installed in parallel).

[0032] The flow rate can be controlled by external actuators, such as an "IGV" upstream of the compressor, an "IGV" downstream of the compressor, a control vane diffuser, and pipes and valves for bypassing the compressor 4.

[0033] The component 14 for adjusting the incoming flow rate may be shared by several compressors connected in parallel.

[0034] Systems 15, 16 for controlling the rotational speed of the turbine 10 may include, for example, an "IGV" which may be variable at the inlet, and / or a throttle valve and / or a valve for bypassing the turbine. This system for controlling the speed can preferably adjust the rotational speed which is the same target for each machine.

[0035] This makes it possible to define speed adjustment parameters for each turbo compressor assembly. This allows the turbo compressor speed to be offset relative to a set value if, for example, inappropriate behavior (e.g., pressure fluctuations, unstable hydraulic behavior, compressor pumping, etc.) is observed.

[0036] By using at least one motor to drive a compressor coupled in parallel to the turbine of the assembly, it becomes possible to control the rotational speed of the compressor / turbine assembly regardless of the operating conditions around the turbine and compressor. The motor output can be adapted based on the output of the turbine and the output required by the compressor. This makes it possible to stabilize the operation of the rotating machine (compressor / turbine). This is particularly advantageous with respect to parallel arrangements of turbo compressors (without motors), which can become rapidly unstable. The proposed configuration also makes it possible to adjust the rotational speed to optimize the operation of the machine. In addition, one or more motors make it possible to increase the output of the compressor relative to the output of the associated turbine. This results in better operation (depending on the cycle configuration).

[0037] The gas flow rate through each turbine can be determined by the turbine's guide vane dimensions and shape, unless a regulating system (e.g., an IGV / expansion valve upstream of the device) can adjust it to some extent.

[0038] The total flow rate in the cycle can be determined by the flow rate in the turbine (and, in some cases, any additional flow rate sent to the cold end of the cycle). This total flow rate is compressed in the compression mechanism. This total flow rate can be distributed between parallel-connected compressors passively (usually via very similar hydraulic circuits) or "actively" (e.g., via IGV, throttle valves, etc.). Finally, the entire cycle gas flow is compressed.

[0039] Preferably, the fluid circuits connected to each compressor are configured to have the same characteristics, particularly with respect to pressure drop (recreation of obstacles to the gas, i.e., the same number of bends / pipe lengths, etc.).

[0040] This configuration is particularly advantageous or efficient when the compressor / turbine speed and the mechanical force of the compressors are the same for each compressor.

[0041] The mechanical force of a compressor is, for example, one of the following: - In the case of a turbo compressor, the mechanical force of the coupled turbine, or - In the case of a motor-driven turbo compressor, the mechanical force of the turbine is supplemented by / added to the mechanical force of the motor.

[0042] Since the motor's output is equal to the compressor's output minus the turbine's output, if all the compressors and all the turbines have the same output, the motors will supply the same output. This configuration may also be advantageous when the compressors are controlled at different speeds but by a compressor diameter (impeller diameter) that is adjusted to provide an optimal compression ratio. In the illustrated embodiment, the cycle circuit comprises three drive motors 12 configured to drive three rotating shafts 11 of three rotary compressors 4 arranged in parallel in the cycle circuit 3. The three parallel-connected compressors 4 are each coupled to three turbines 11.

[0043] Of course, this configuration is not the only one. Therefore, any other configuration is possible, for example, two or more compressors, turbines connected in series and / or parallel (the architecture is adapted to balance the turbine output on each of the shafts connecting the turbines to the compressors). For example, at least one impeller (compressor / turbine) is located at each end of the motor drive shaft. It is preferable to have two or more motors driving the compressors. Parallel connected compressors 4 have the same pressure difference (between their inlets and outlets). However, the flow rates within these parallel connected compressors 4 can fluctuate and differ. This can cause problems and instability if the parallel connected compressors 4 are identical.

[0044] The control described above makes it possible to correct this problem. The control also makes it possible to adjust the rotational speed of the coupled turbine 10 to a predetermined operating point, in particular the turbine's optimal operating point, i.e., its maximum output.

[0045] The electronic control and command member 20 can also be configured to manage the speed of one or more motors 12 of a parallel-connected motor turbocompressor, for example, via a frequency variator (electric motor). This motor speed allows for adjustment of the optimal operating point of the turbine and compressor.

[0046] The electronic control and command member 20 may be configured to apply the same set value to the rotational speed of the turbine 10 coupled to the compressor 4.

Claims

1. A cycle gas refrigerator (2) comprising a cycle circuit (3) containing a cycle gas comprising at least one of nitrogen, helium, and hydrogen, wherein the cycle circuit (3) is configured to supply the cycle fluid to a thermodynamic cycle that brings the cycle fluid to a predetermined cryogenic temperature at at least one end of the cycle circuit (3), the cycle circuit (3) comprises a mechanism (4) for compressing the cycle fluid, a mechanism (5, 6, 7, 8) for cooling the cycle fluid, and a mechanism (10) for expanding the cycle fluid, the mechanism (10) for expanding the cycle fluid comprises at least two turbines (10) rotatably mounted on each rotating shaft (11), the compression mechanism comprises at least three rotary compressors (4) arranged in parallel with the cycle circuit (3) and mounted on each of the three rotating shafts, at least two of the rotating shafts are coupled to the turbines (10) respectively to recover the work of expanding the cycle fluid in order to compress the cycle fluid, in the cycle gas refrigerator (2), the cycle gas refrigerator comprises The turbine (10) is coupled to at least one motor (12) for driving at least one of the rotating shafts (11) that support the bins (10) and compressors (4), and the at least two parallel-connected compressors (4) are each associated with a member (9) for measuring the flow rate passing through the compressor (4) and a member (14) for adjusting the flow rate entering the compressor (4), one or more upstream or downstream movable guide members such as "IGVs", and the at least two turbines coupled to the compressors (4) Each (10) comprises a sensor (17) for measuring the rotational speed of the turbine (10) and a system (15, 16) for controlling the rotational speed of the turbine (10), and the refrigerator (1) comprises an electronic control and command member (20) which includes a microprocessor and is configured to receive measured values ​​from the member (9) for measuring the flow rate and the sensor (17) for measuring the speed, and to command the member (14) for adjusting the flow rate, and the parallel-connected compressors are identical,A cycle gas refrigerator characterized in that the electronic control and command member (20) is configured to apply a set value for the flow rate entering the compressors (4), which is the same for all of the parallel-connected compressors (4).

2. The refrigerator according to claim 1, characterized in that the electronic control and command member (20) is configured to apply the same set value to the rotational speed of the turbine (10) coupled to the compressor (4).

3. The chiller according to claim 1 or 2, wherein the member (14) for adjusting the flow rate entering the compressor (4) comprises at least one of the following: one or more movable guide members, an upstream inlet guide vane "IGV", a variable vane diffuser downstream of the impeller of the compressor, and a system for bypassing the compressor.

4. The refrigerator according to any one of claims 1 to 3, characterized in that it has a member (14) for adjusting the flow rate entering the compressor (4), which is shared by at least some of the parallel-connected compressors.

5. The chiller according to any one of claims 1 to 4, wherein the system (15, 16) for controlling the rotational speed of the turbine (10) comprises at least one of an inlet guide vane "IGV", a throttle valve, and a system for bypassing the turbine.

6. The refrigerator according to any one of claims 1 to 5, further comprising three or more drive motors (12) configured to drive the three rotating shafts (11) of the three rotary compressors (4) arranged in parallel in the cycle circuit (3).

7. The refrigerator according to claim 1, characterized in that the electronic control and command member (20) is configured to manage the speed of one or more motors (12).

8. The refrigerator according to claim 7, characterized in that the one or more motors (12) are electric motors, and the electronic control and command member (20) is configured to command the rotational speed of the one or more motors (12) to achieve the same compression ratio in each compressor.

9. Equipment for liquefying a flow of supply gas, comprising: a supply pipe (18) configured to be connected to a supply source (19) of the supply gas to be liquefied, for example, hydrogen; and a set of heat exchangers (19) that exchange heat with the flow of the supply gas transported by the supply pipe (18); wherein the equipment (2) comprises a refrigerator (2) configured to exchange heat with the set of heat exchangers (19) and cool the flow of the supply gas, wherein the refrigerator (2) is as described in any one of claims 1 to 8.

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