Patent Application
20250155175
The invention relates to a refrigeration device and method.
In certain embodiments, the invention may relate more particularly to a refrigeration device refrigerating to a low temperature, notably a cryogenic temperature, which is to say to a temperature comprised between minus 100 degrees centigrade and minus 273 degrees centigrade, comprising a working circuit forming a loop and containing a working fluid, the working circuit forming a cycle comprising, in series: a compression mechanism for compressing the working fluid, a cooling mechanism for cooling the working fluid, an expansion mechanism for expanding the working fluid, and a heating mechanism for warming the working fluid, the device comprising a cooling exchanger intended to extract heat from at least one member by supplying it a determined refrigeration power through exchange of heat with the working fluid circulating in the working circuit after it has been expanded in the expansion mechanism, the compression mechanism comprising at least one electric motor driving the rotation of a shaft bearing at least one compressor impeller at a rotational speed that is controlled between a minimum speed and a maximum design speed which is determined by the characteristics of the motor, the device being of the type having a variable refrigeration power that is controlled by regulating the rotational speed of the motor, the device comprising an electronic controller configured to control the refrigeration power supplied by the refrigeration device by controlling the rotational speed of the motor, the electronic controller being configured to receive a demand signal demanding the determined cold power to be delivered and, in response, to control the rotational speed of the motor in order to meet said cold-power demand.
In certain embodiments, the invention may also relate in particular to the management of the load of a cryogenic machine on the basis of a control setpoint originating from a client system/from an operator that is to be cooled, while keeping the system automatically safe.
In certain embodiments, the invention may relate in particular to the autonomous management of the speed of a motor in the event of poor operating conditions (insufficient flowrate for cooling, temperature of the fluid that is to be cooled already being too low, etc.). For this type of device, the cold power supplied is dependent on the speed of the motors. The greater the speed of the motor, the more cold power the machine will deliver to the client fluid. When the machine is operating nominally (cooling the client fluid), the temperature of the working fluid is dictated by the temperature of the client fluid. The machine's internal regulating control point is based on the temperature of the working fluid. This means to say that the speed controller will adjust the speed of the motor in order to maintain this temperature of the working fluid at this setpoint value. If this measured temperature of the working fluid exceeds the setpoint value, the motor will accelerate. By contrast, if this measured temperature of the working fluid is below the setpoint value, the motor will decelerate. This control setpoint is generally colder than the setpoint temperature for the client fluid that is to be cooled. The speed controller will demand an acceleration in the motor speed, without having any effect on the temperature of the working fluid but achieving an increase in the cold power supplied.
For such applications, it is known practice to employ regulation of the PID control type where one parameter (motor speed) is regulated in order to maintain a measurement (the cold power of the machine) at a certain setpoint (the operating point originating from the client).
The regulation of such a device is dependent on the quality of measurement of the parameters. If one of the sensors in the cold-power measurement chain is lost, it is no longer possible to regulate the load on the machine correctly. In addition, in known systems, the responsiveness of the regulation is poor because it takes a certain amount of time for the system to reach the setpoint. Excessively rapid regulation of the “PID” control type carries a significant risk of load fluctuation.
An objective of certain embodiments of the present invention is to eliminate all or some of the above-described disadvantages of the prior art.
To this end, the device according to the invention, which moreover corresponds to the general definition thereof given in the above preamble, is essentially characterized in that the electronic controller is configured to limit the maximum operating speed of the motor to a value less than or equal to the maximum design speed, in nominal operation, which is to say when the device is supplying the determined cold power, the electronic controller being configured to set the maximum operating speed of the motor to the rotational speed that supplies the determined cold power and to regulate the rotational speed of the motor as a function of the demand for cold power without exceeding said maximum operating speed.
The controller will limit the motor speed up to the maximum value. The invention therefore consists in regulating the power delivered by modifying the maximum speed that can be demanded by the speed controller. The regulation on the basis of the target temperature that the working fluid is to achieve remains active. Because the maximum speed of the motor or motors is managed, it thus becomes possible to regulate the cold power delivered by the machine to the client fluid that is to be cooled.
Furthermore, embodiments of the invention may have one or more of the following features:
The invention also relates to a refrigeration method for refrigerating to a low temperature, which is to say to a temperature comprised between minus 100 degrees centigrade and minus 273 degrees centigrade, a member such as a stream of fluid, using a refrigeration device according to any one of the features above or below, comprising regulation of the cold power delivered by the device by controlling the maximum operating speed of the motor.
According to one possible particular feature, the method comprises a step of receiving a demand signal demanding a determined cold power that is to be delivered by the device, a step of determining a determined rotational speed of the motor in order to meet said demand for power, a step of setting the maximum operating speed to the determined rotational speed value and a step of maintaining the rotational speed of the motor at said maximum operating speed.
The invention may also relate to any alternative device or method comprising any combination of the features above or below within the scope of the claims.
The invention will be understood better from reading the following description and from studying the accompanying figures. These figures are given only by way of illustration and do not in any way limit the invention.
Further particular features and advantages will become apparent upon reading the following description, which is provided with reference to the figures, in which:
The refrigeration device 1 refrigerating to a cryogenic temperature, which is to say operating at a low temperature comprised, for example, between minus 100 degrees centigrade and minus 273 degrees centigrade, comprises a working circuit 10 forming a loop and containing a working fluid.
The working circuit 10 forms a cycle comprising, in series: a compression mechanism 2, 3 for compressing the working fluid, a cooling mechanism 6, 16 for cooling the working fluid, an expansion mechanism 7 for expanding the working fluid, and a heating mechanism 6, 8 for warming the working fluid.
The device 1 comprises a cooling exchanger 8 intended to extract heat from at least one member 25 or user by supplying it a determined refrigeration power P through exchange of heat with the working fluid circulating in the working circuit 10 after it has been expanded in the expansion mechanism 7. The cooling exchanger 8 intended to extract heat from at least one member 25 comprises, for example, a fluid circulation passage for cooling a member 25 consisting of a stream of fluid that is to be cooled.
The compression mechanism 2, 3 comprises at least one electric motor 11 driving the rotation of a shaft 15 bearing at least one compressor impeller 2 at a rotational speed that is controlled between a minimum speed and a maximum design speed Vmc of the motor, which speed is determined, for example, by the characteristics of the design and manufacture of the motor 11.
As illustrated in the various examples, the compression mechanism 2, 3 may comprise one or more compressor impellers 2 arranged, where applicable, in series and/or in parallel in the working circuit 10 and forming one or more compression stages for the working fluid. The compressor impeller or impellers 2 may be driven in rotation by one or more motors 11. The expansion mechanism 7 may, for its part, comprise one or more turbines 7 (and/or expansion valve(s)) positioned, where applicable, in series and/or in parallel in the working circuit 10 and forming one or more expansion stages for the working fluid.
At least one of the turbines 7 may be mounted on the same shaft 15 of a motor 11 driving the rotation of at least one compressor impeller 2.
The refrigeration device is of the type having a variable refrigeration power P that is controlled by regulating the rotational speed V of the motor 11.
For example, and as schematically indicated in [
For example, the electronic controller 12 may be configured to calculate the value for the rotational speed V of the motor as a function of the demand for cold power using a formula in which said speed is given by a polynomial function, of degree greater than or equal to two, of the cold power P, said formula being predefined (established or calculated) on the basis of measured actual measurements of the performance of the device 1.
For example, these actual values are measured on a device and the coefficients (the formula) can be defined for an entire range of identical devices (or each machine each time).
As illustrated, the device 1 comprises an electronic controller 12 configured to control the refrigeration power P supplied by the refrigeration device 1 by controlling the rotational speed V of the motor or motors 11. What this means to say is that, when there are several motors, the electronic controller 12 may be configured to control the rotational speed V of all or some of the motors 11 in order to meet said demand for cold power.
The electronic controller 12 is, for example, a speed controller comprising a microprocessor and/or a computer. It may be integrated into the device 1 or at least partially remote therefrom.
The electronic controller 12 is, in particular, configured to receive a demand signal 13 demanding the determined cold power P to be delivered and, in response, to control the rotational speed V of the motor 11 in order to meet said cold-power demand.
According to one advantageous particular feature, the electronic controller 12 is configured to limit the maximum operating speed Vmf of the motor 11 to a value less than or equal to the maximum design speed Vmc. In addition, in nominal operation, which is to say when the device 1 is supplying the determined cold power, the electronic controller 12 is configured to set the maximum operating speed Vmf of the motor to the rotational speed that supplies the determined cold power P and to regulate the rotational speed V of the motor as a function of the demand for cold power without exceeding said maximum operating speed Vmf. (For example, Vmf is a percentage of Vmc: cf. [
What that means to say is that, in operation, the speed of the motor can be varied as a function of the demand for cold power P.
The maximum operating speed Vmf of the motor can be set, for example upon start-up of the device 1 (upon start-up of the installation), and it is the actual speed that enables the nominal power demanded by the client or user 25 to be delivered. What is meant by “nominal operation” is, for example, the operation of the device when it is supplying 100% of the nominal power.
This allows the setpoint cold power that is to be supplied to be achieved rapidly in comparison with known regulation of the PID control type. This solution also makes for greater responsiveness in reaching the control setpoint (pressure, temperature, etc.) in the application that is to be cooled.
This may render the operation independent with respect to the actual measurements of cold power supplied. This avoids any possible error in regulation in the event of rogue measurements (sensor drift for example).
For example, the device 1 comprises at least one temperature sensor 9, 19 sensing the temperature of the working fluid in the working circuit 10, for example at an inlet and/or at an outlet of the expansion mechanism 7, and the electronic controller 12 is configured to receive the measurement 14 from the at least one temperature sensor 9, 19.
For example, the electronic controller 12 is configured to control the rotational speed V of the motor 11 in order to achieve a target temperature value at the at least one temperature sensor 9, 19 in the working circuit.
The target temperature may be constant and equal to the cold temperature demanded by the client application that is to be cooled.
The regulating system may be autonomous as regards the temperature management (the controller 12 remains active because it is only the maximum speed that is being regulated). In the event of a problem with the flowrate of the fluid 25 that is to be cooled (if a pump ceases to operate or in the event of some other problem), the controller 12 will be able to adjust the rotational speed of the motor so that the working fluid does not drop below its setpoint temperature.
The maximum operating speed of the motor Vmf is preferably limited to a value strictly lower than the maximum design speed of the motor Vmc.
In other applications it is possible for the maximum operating speed of the motor Vmf to be equal to the maximum design speed of the motor Vmc. In these applications (for example the liquefaction of a biomethane), the temperature of the client fluid that is to be cooled (for example at the outlet of a cooling exchanger) is used as the control parameter for regulating the speed of the motor or motors. The measured temperature leads to a correction of the target temperature setpoint, which then leads to a variation in the speed setpoint for the motor or motors (for example as a percentage % of the maximum operating speed of the motor).
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2201298 | Feb 2022 | FR | national |
This application is a § 371 of International PCT Application PCT/EP2022/086870, filed Dec. 20, 2022, which claims the benefit of FR2201298, filed Feb. 15, 2022, both of which are herein incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086870 | 12/20/2022 | WO |
