US20090129941A1 - Method for controlling a pump arrangement, and pump arrangement - Google Patents

Method for controlling a pump arrangement, and pump arrangement Download PDF

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Publication number
US20090129941A1
US20090129941A1 US12/263,343 US26334308A US2009129941A1 US 20090129941 A1 US20090129941 A1 US 20090129941A1 US 26334308 A US26334308 A US 26334308A US 2009129941 A1 US2009129941 A1 US 2009129941A1
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Prior art keywords
pump
volume flow
bypass valve
rotational speed
delivery height
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Abandoned
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US12/263,343
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English (en)
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Sebastian Haas
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Linde GmbH
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Linde GmbH
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Publication of US20090129941A1 publication Critical patent/US20090129941A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04951—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network
    • F25J3/04963—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network and inter-connecting equipment within or downstream of the fractionation unit(s)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B15/00—Pumps adapted to handle specific fluids, e.g. by selection of specific materials for pumps or pump parts
    • F04B15/06—Pumps adapted to handle specific fluids, e.g. by selection of specific materials for pumps or pump parts for liquids near their boiling point, e.g. under subnormal pressure
    • F04B15/08—Pumps adapted to handle specific fluids, e.g. by selection of specific materials for pumps or pump parts for liquids near their boiling point, e.g. under subnormal pressure the liquids having low boiling points
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/04—Combinations of two or more pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04096—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of argon or argon enriched stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04781—Pressure changing devices, e.g. for compression, expansion, liquid pumping
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04787—Heat exchange, e.g. main heat exchange line; Subcooler, external reboiler-condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04818—Start-up of the process
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04824—Stopping of the process, e.g. defrosting or deriming; Back-up procedures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/02—Motor parameters of rotating electric motors
    • F04B2203/0209—Rotational speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2205/00—Fluid parameters
    • F04B2205/05—Pressure after the pump outlet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/22—Compressor driver arrangement, e.g. power supply by motor, gas or steam turbine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/02—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams using a pump in general or hydrostatic pressure increase
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/10—Mathematical formulae, modeling, plot or curves; Design methods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/62—Details of storing a fluid in a tank

Definitions

  • the present invention relates to a method for controlling a pump arrangement which is used, for example, in cryotechnical plants.
  • the invention further relates to an arrangement comprising one or more pumps for providing pressurized cryogenic liquid, the arrangement being suitable, for example, for use in an air liquefaction plant.
  • redundant pumps are mostly operated in parallel, in order to maintain the necessary pressure in the low-temperature system in case of failure of one of the pumps.
  • pairs of redundant pumps may be provided, with one working pump being continuously in operation and, in case of failure, a substitute pump starting and replacing the performance of the failed pump.
  • So-called “slow-roll” operating modes are known for such substitute pumps, with the drive motor being active, the pump performs, however, only minimal delivery work.
  • the rotational speed of the substitute pump must reach the rotational speed of the failed pump as quickly as possible.
  • the rotational speed of the pump performing delivery is determined by operation specifications of the plant in question and is adjusted in a closed-control loop.
  • the rotational speed of an asynchronous motor is essentially predetermined by the three-phase frequency at which it is operated. For this reason, in conventional closed-loop control systems, a frequency converter is used, which provides the three-phase frequency for the motor driving the pump.
  • a corresponding closed-loop control unit determines the three-phase frequency for the pumps or asynchronous motors depending on the product present on the output side of the pump.
  • a method for controlling a pump arrangement comprising a fluid-delivering pump having a pump drive, and a bypass line having a bypass valve, is provided.
  • the bypass line is to return fluid to a reservoir provided at the pump inlet.
  • the bypass valve is controlled so that the volume flow through the pump at a corresponding delivery height lies between a cavitational volume flow and the cavitational volume flow increased by a predetermined maximum deviation in the volume flow.
  • a control line as close as possible to the cavitation boundary can be defined for the operating point of the pump, which results in a favourable reduction of the volume flow which, in turn, rules out the possibility of cavitation occurring.
  • the proposed closed-loop control of the bypass valve causes the volume flow to be reduced at least partially during ramping-up, and is close to a lower cavitation boundary curve.
  • the bypass valve is preferably controlled in such a way that the volume flow at a corresponding delivery height is situated in a volume flow range between a lower limit volume flow and the cavitational volume flow increased by the predetermined maximum deviation of the volume flow.
  • control curve for the volume flow which runs essentially parallel to the lower cavitation boundary.
  • the lower limit volume flow then lies between the control curve and the cavitation boundary, for example, and an upper limit volume flow lies to the right of the control curve within a corresponding delivery height/volume flow diagram.
  • the range is specified so that the cavitational volume flow is never undercut, not even in the case of overshootings in the closed-loop control.
  • an implementation of the method as a cavitation limiting controller appears appropriate to control the bypass valve on the basis of the difference between a pump inlet pressure and an outlet pressure and the current volume flow.
  • advantage can be taken of the fact that the ramping-up procedure of the pump drive runs essentially along a cavitation boundary. This ensures a particularly low volume flow.
  • a current volume flow is calculated as a function of the pressure difference between an inlet and an outlet side of the pump and/or the current rotational speed of the pump drive.
  • a pump provided as a substitute pump in slow-roll or stand-by mode normally features an open bypass. Based on this situation, the volume flow is then minimized in order to bring the corresponding substitute pump to the predetermined rotational speed as quickly as possible.
  • a higher-level pressure controller provides, for example, a rotational speed for the pump depending on the queried product in the output line.
  • a corresponding pressure controller then provides a target rotational speed for these pumps.
  • the bypass valve should be closed so quickly as to ensure that the rotational speed is not increased significantly. For example, if the entire ramp-up time of the corresponding pump amounts to 10 seconds, closing can be effected within one second.
  • an operating point of the pump along a delivery height-volume flow characteristic at a constant rotational speed is used during the initial power-up phase.
  • the bypass valve can be ramped, i.e., its orifice varied by a predetermined value in a predetermined time. It is also possible to set a target value for the controller acting on the bypass valve, with the valve position varying correspondingly over time during this initial power-up phase.
  • the cavitational volume flow corresponds to a minimum volume flow required to avoid cavitation at a corresponding delivery height.
  • a minimum acceptable volume flow rate is thus ensured without inducing cavitation.
  • the pump is thereby preferably operated at an operating point which runs essentially in parallel to a cavitation boundary of a set of delivery height-volume flow characteristic lines of the pump.
  • Closing the bypass valve once a predetermined delivery height or a predetermined outlet pressure has been reached during a third power-up phase For example, as soon as the pressure required by a pressure controller has been reached on the outlet side, the volume flow can also be increased again, which is effected by closing the bypass valve. On principle, this process can be repeated until a pressure controller acting on the bypass valve records a maximum pressure. Then the bypass valve would have to be opened.
  • bypass valve On principle, other operational situations may also necessitate the closing of the bypass valve. If, for example, fluid is withdrawn on the outlet side, the closed-loop control can induce a reduction of the bypass valve orifice.
  • the method is suited for use with an asynchronous motor as a pump drive with a three-phase frequency which corresponds to the predetermined target rotational speed.
  • the current rotational speed can also be approached approximately by taking the synchronous rotational speed into account.
  • the resulting slip can be neglected.
  • a pump arrangement comprising at least one pump, one reservoir and one control device.
  • the pump has a pump drive, and the reservoir is coupled to the pump on the pump outlet side via a bypass line.
  • the bypass line is equipped with a bypass valve.
  • the reservoir also supplies a fluid to be delivered to the pump inlet side.
  • the control device is designed in such a way that a method described above is performed.
  • the pump arrangement can comprise a cavitation limit control device which controls the bypass valve as a function of the current volume flow through the pump and a current rotational speed of the pump drive of the pump.
  • a closed-loop control can also be effected as a function of the pressure difference between input and output sides, the current rotational speed and/or the delivery height.
  • the cavitation limit control device is provided as otherwise damage due to cavitation may occur, in particular with cryogenic fluids.
  • a pressure controller recording the outlet pressure can be provided, which controls the bypass valve so that a predetermined maximum outlet pressure is not exceeded. However, control by the cavitation limit control device should have priority.
  • One or several corresponding pump arrangements are particularly suitable for use in air separation units having cryogenic pumps.
  • the control device can also specify the target rotational speed of the corresponding cryogenic pump as a function of the operating specifications for a process for air separation.
  • the hydraulic torque can be minimized by proceeding in accordance with the invention. This accelerates the ramping-up procedure. Fluctuations of pressure or the volume flow rate are reduced significantly.
  • the method can also be used and implemented for any substitute or operating pump in cryogenic pump applications working in parallel.
  • One variant of the invention provides a computer program product which induces implementation of a corresponding method for controlling a pump drive on a software-controlled computer or control unit.
  • a PC or a computer of a control room for the closed-loop and open-loop control of plants can be used as software-controlled computer or control unit, with the corresponding software being installed.
  • the software pro-product can, for example, be implemented in the form of a data medium such as a USB stick, floppy disc, CD-ROM, DVD, or can be implemented on a server unit as a downloadable program file.
  • FIG. 1 a representation of a plant having a plurality of controllable pumps for providing a pressurized cryogenic fluid
  • FIG. 2 a schematic representation of a pump arrangement suitable for the implementation of one variant of the ramping-up method in accordance with the invention.
  • FIG. 3 a delivery height-volume flow diagram illustrating power-up phases of a pump drive.
  • ASU air separation unit
  • redundant pumps are provided as substitute pumps in the case of failure of the working pump, properly speaking.
  • FIG. 1 It is also conceivable that several individual plant components are supplied with pressurized cryogenic liquid from a common reservoir or tank. This is represented schematically in FIG. 1 , for example.
  • a common high-pressure liquid line 1 is provided, which is supplied with high-pressure liquid by the three pumps 2 , 3 , 4 .
  • the pumps are supplied with the corresponding product via a supply line 5 from a joint reservoir or tank 6 .
  • a bypass return line 7 , 8 , 9 each with a pressure-controlled valve 10 , 11 , 12 , is provided.
  • each pump 2 , 3 , 4 is secured against the joint high-pressure liquid line 1 via a check valve 13 , 14 , 15 .
  • three plant components are connected to the joint high-pressure liquid line 1 .
  • two heat exchangers 16 , 17 of air separation units and a back-up system 18 are connected to the joint high-pressure liquid line 1 .
  • the product pressure is controlled respectively by the pressure-controlled valves 19 , 20 .
  • the product quantity required respectively is also controlled via valves 21 , 22 .
  • high-pressure liquid is withdrawn from the joint line 1 by the back-up system 18 via a valve 24 driven by a controller 23 .
  • the pressure required is controlled by activating the pumps 2 , 3 , 4 in the joint high-pressure line 1 .
  • the pump bypasses 8 , 9 are closed, and an appropriate three-phase frequency is pre-determined for the pumps or the asynchronous motors implemented in them.
  • the substitute pump 2 then, for example, runs in slow-roll mode, and the corresponding bypass valve is opened 100%.
  • the number of pumps 2 , 3 , 4 provided corresponds to the number of plant components 16 , 17 being supplied by the joint high-pressure line 1 . If application of the back-up system becomes necessary, the third pump must also be powered up.
  • the controller or the open-loop control unit 25 sets a predetermined three-phase frequency nsyn on the pumps as a function of the operation specifications of the other plant components connected.
  • FIG. 2 shows a schematic sectional view of a pump arrangement, as it can be configured in FIG. 1 for the pumps 2 , 3 , 4 .
  • Pump 2 is driven by a motor 26 , with the respective rotational speed controlled via a control signal CT 3 by an evaluation device 27 .
  • the pressure controller 25 which measures the outlet pressure of the joint liquid line 1 delivers a target rotational speed NZ to the evaluation device 27 .
  • the current rotational speed nakt of the motor 26 is provided via a speed sensor 28 .
  • the motor 26 can preferably be run within an operating range in which its torque is on principle at its maximum value.
  • this can be achieved, for example, by operating the drive 26 , which is designed as an asynchronous motor, in the proximity of its breakover point.
  • a cavitation limit control which comprises a cavitation limit control device 30 delivering a control signal CT 1 to the control device or interrogator device 32 which operates the bypass valve.
  • a pressure gauge 29 is provided on the pump inlet side, which measures the inlet pressure p I and delivers it to the cavitation limit control device 30 .
  • a pressure controller 31 is provided on the outlet side which, on the one hand, delivers the cavitation limit controller 30 with the outlet pressure p O and, on the other hand, communicates a control signal CT 2 to the control device 32 to open the bypass valve 10 if the maximum admissible outlet pressure is exceeded.
  • the various control mechanisms such as cavitation limit control and pressure controller 31 for the bypass valve 10 can be effected on principle independently of one another, with the cavitation limit controller 30 supplying a control signal CT 1 which has priority over the control signal CT 2 .
  • the controller 32 it is possible for the controller 32 always to perform a maximum selection between the values of the control signal CT 1 from the cavitation limit controller 30 and the control signal CT 2 from the pressure controller 31 . This ensures that cavitation is prevented while the output pressure is nevertheless controlled reliably.
  • the controller 31 represented as a pressure controller (PIC) can be also designed as a manual controller (HIC) in other versions of a corresponding pump arrangement.
  • PIC pressure controller
  • HIC manual controller
  • the delivery rate P Q provided by the pump results from the volume flow ⁇ dot over (V) ⁇ and the specific delivery work Y, which represents the work involved in the flow. This can be represented by the following equation:
  • ⁇ is the density of the fluid, g the acceleration of gravity and H the delivery height which can be derived from the specific delivery.
  • the corresponding variables are accessible via corresponding sensors or controllers, as shown in FIG. 2 .
  • the hydraulic power P Q to be procured by the pump results from the mechanical output power P M multiplied by the efficiency ⁇ .
  • FIG. 3 shows, on the basis of a delivery height/volume flow diagram, a possible development of the operating point of a pump during ramping-up in accordance with a variant of the method to power up a pump drive 26 .
  • FIG. 3 shows the corresponding characteristic lines n 1 , n 2 , n 3 , n 4 , n 5 in the delivery height-volume flow diagram, with n 1 -n 5 standing for various rotational speeds of the pump drive 26 .
  • the volume flow ⁇ dot over (V) ⁇ is indicated on the X axis, and the delivery height H on the Y axis.
  • the delivery height H is proportional to n 2 if a constant efficiency ⁇ can be assumed.
  • the rotational speed n increases, the surfaces enclosed by the characteristic lines n 1 -n 5 in the plane increase as well.
  • n 1 in terms of possible slow-roll rotational speed can correspond to 45%-50% of the maximum desired rotational speed n 5 .
  • cavitation boundaries KG 1 and KG 2 are shown. If the volume flow ⁇ dot over (V) ⁇ undercuts the cavitation boundary KG 1 at a predetermined rotational speed, e.g. n 2 , there is a high risk of cavitation, and thus a risk of destruction of the pump.
  • the resulting braking moment can be illustrated based on FIG. 3 by the rectangular surface which is defined, in the case of a predetermined operating point, e.g. BP 1 , by the operating point and the origin of the diagram.
  • the current volume flow ⁇ dot over (V) ⁇ can be determined from a diagram of the pump manufacturer via the rotational speed n and the pressure difference ⁇ p.
  • the cavitation limit controller 30 As these variables are supplied to the cavitation limit controller 30 , as shown in FIG. 2 , the latter is able to prevent the cavitation boundary KG 1 from being undercut by opening the bypass valve 10 . In normal operation, if sufficient product is withdrawn from the liquid line 1 , the bypass valve is normally completely closed; the cavitation limit controller 30 indicates an orifice opened 0% via the control signal CT 1 .
  • a first power-up phase which is suggested in FIG. 3 by P 1 as a dashed arrow, the bypass valve 10 is controlled so that the rotational speed only fluctuates by a low value ⁇ n, based on the current speed n 1 , and that starting from BP 1 , an operating point BP 2 is reached which features a volume flow increased by the minimum required volume flow of the cavitation boundary line KG 1 (cavitational volume flow) at the predetermined delivery height.
  • a maximum deviation of the rotational speed nakt of 10%, preferably 5%, can be defined.
  • a distance from the cavitational volume flow is ensured which corresponds to a control line. The resulting distance is such that even extraordinary fluctuations in pump operation cannot cause a volume flow below the cavitation boundary.
  • bypass valve 10 When the bypass valve 10 is completely open, it is closed during the first power-up phase P 1 , or the flow rate is reduced. During this first power-up phase P 1 , the rotational speed is increased only slightly by ⁇ n, with the volume flow ⁇ dot over (V) ⁇ being reduced significantly, which results in a lower hydraulic braking torque PM.
  • the position of the bypass valve 10 is controlled departing from the operating point BP 2 so that an operating point BP 3 is reached which has a higher volume flow and a higher delivery height H than the operating point BP 2 .
  • the bypass valve is controlled so that the operating point is parallel to the cavitation boundary KG 1 . To this effect, a distance in the volume flow is kept from the cavitation boundary.
  • the corresponding control parameters permitting control of the the pump in accordance with the second power-up phase P 2 can be determined experimentally and optimized for example in dynamic simulations.
  • a control line RL which runs parallel to the upper cavitation boundary KG 1 at a distance of ⁇ dot over (V) ⁇ d ⁇ dot over (V) ⁇ , with ⁇ dot over (V) ⁇ >d ⁇ dot over (V) ⁇ .
  • an area VB is defined around the control line RL which should not be exceeded by the operating point during the second power-up phase P 2 .
  • a lower limit volume flow results from RL ⁇ d ⁇ dot over (V) ⁇ and an upper limit volume flow from RL+d ⁇ dot over (V) ⁇ .
  • control line RL corresponds preferably to a volume flow ⁇ dot over (V) ⁇ , which is 2%-10% above the respective cavitational volume flow.
  • d ⁇ dot over (V) ⁇ depends on the control parameters, the control accuracy and the actual implementation of the plant. It should be ensured that the area to the right of the cavitation line for the operating point is as narrow as possible.
  • a third power-up phase P 3 the outlet pressure of the pump has risen sufficiently, so that fluid is supplied to the product system or the delivery line 1 .
  • the volume flow ⁇ dot over (V) ⁇ increases more significantly and the bypass valve closes.
  • the operating point BP 4 is reached by increasing the rotational speed.
  • the operating point BP 4 is at a delivery height or corresponds to an outlet pressure which corresponds to the target value of the pressure controller 25 acting on the pump speed.
  • the dash-dotted line PIC 25 The other horizontal, dash-dotted line PIC 31 in the delivery height-volume flow diagram of FIG. 3 corresponds to the target value of the pressure controller 31 acting on the bypass valve.
  • the invention provides a method which can be implemented in the corresponding closed-loop control or control room computers of plants and permits minimization of the ramp-up duration of a pump drive, especially of cryogenic internal compression centrifugal pumps.
  • the method can be used for individual pumps and for redundant substitute pumps with several pumps operated simultaneously, and reduces the fluctuations of pressure and product rates on the output side.
  • the method can also be integrated in a straightforward fashion into existing control concepts and is independent of the number of pumps used and operated.
  • a corresponding analog cavitation limit control for the upper cavitation limit KG 2 prevents moreover, in the case of large-size bypass valves, possible damage due to cavitation on the pump impeller concerned, if e.g. a substitute pump is running in slow-roll mode.
  • an area can be determined analogously just below the upper cavitational volume flow KG 2 where an operating point should exist.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Reciprocating Pumps (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
US12/263,343 2007-11-16 2008-10-31 Method for controlling a pump arrangement, and pump arrangement Abandoned US20090129941A1 (en)

Applications Claiming Priority (2)

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EP07120867.2 2007-11-16
EP07120867A EP2060788B1 (de) 2007-11-16 2007-11-16 Verfahren zum Ansteuern einer Pumpenanordnung und Pumpenanordnung

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US20120173027A1 (en) * 2010-12-30 2012-07-05 Itt Manufacturing Enterprises, Inc. Method and Apparatus for Pump Control Using Varying Equivalent System Characteristic Curve, AKA an Adaptive Control Curve
US20130312386A1 (en) * 2011-02-01 2013-11-28 Alstom Technology Ltd Combined cycle power plant with co2 capture plant
US20140336829A1 (en) * 2012-01-18 2014-11-13 Festo Ag & Co. Kg Method for Configuring a Fluid Control Unit, Computer Program Product and Fluidic System
US20150059749A1 (en) * 2012-04-02 2015-03-05 Metran Co., Ltd. Pump unit and respiratory assistance device
US20160186930A1 (en) * 2014-02-28 2016-06-30 Praxair Technology, Inc. Pressurized product stream delivery
US9846416B2 (en) 2011-12-16 2017-12-19 Fluid Handling Llc System and flow adaptive sensorless pumping control apparatus for energy saving pumping applications
US10048701B2 (en) 2011-12-16 2018-08-14 Fluid Handling Llc Dynamic linear control methods and apparatus for variable speed pump control
CN108591041A (zh) * 2018-07-06 2018-09-28 华能国际电力股份有限公司 给水泵最小流量再循环阀控制系统及方法
WO2018192780A1 (en) * 2017-04-19 2018-10-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Liquefied gas supply spare system and liquefied gas spare supply method
EP3699534A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
EP3699535A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
CN116951800A (zh) * 2023-09-15 2023-10-27 广东美的暖通设备有限公司 控制方法、控制装置、双循环制冷系统及存储介质

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DE102011015903B4 (de) 2011-04-01 2021-12-16 Robert Bosch Gmbh Pumpenanordnung
DE102012009136A1 (de) * 2012-05-05 2013-11-07 Robert Bosch Gmbh Verfahren zum Betreiben einer Fluidpumpe
DE102022110368A1 (de) 2022-04-28 2023-11-02 Audi Aktiengesellschaft Verfahren zum Betreiben eines Fluidkreislaufs für ein Kraftfahrzeug sowie entsprechender Fluidkreislauf

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FR2439881A1 (fr) * 1978-10-23 1980-05-23 Air Liquide Procede et dispositif de demarrage d'une pompe a liquide cryogenique
DE10228673B4 (de) * 2002-06-27 2004-06-03 Holter Regelarmaturen Gmbh & Co. Kg Rückdruckregulator
FR2866929B1 (fr) * 2004-03-01 2008-04-04 Air Liquide Systeme de pompage d'un fluide cryogenique

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US8700221B2 (en) * 2010-12-30 2014-04-15 Fluid Handling Llc Method and apparatus for pump control using varying equivalent system characteristic curve, AKA an adaptive control curve
US20120173027A1 (en) * 2010-12-30 2012-07-05 Itt Manufacturing Enterprises, Inc. Method and Apparatus for Pump Control Using Varying Equivalent System Characteristic Curve, AKA an Adaptive Control Curve
US20130312386A1 (en) * 2011-02-01 2013-11-28 Alstom Technology Ltd Combined cycle power plant with co2 capture plant
US9846416B2 (en) 2011-12-16 2017-12-19 Fluid Handling Llc System and flow adaptive sensorless pumping control apparatus for energy saving pumping applications
US10048701B2 (en) 2011-12-16 2018-08-14 Fluid Handling Llc Dynamic linear control methods and apparatus for variable speed pump control
US20140336829A1 (en) * 2012-01-18 2014-11-13 Festo Ag & Co. Kg Method for Configuring a Fluid Control Unit, Computer Program Product and Fluidic System
US9886041B2 (en) * 2012-01-18 2018-02-06 Festo Ag & Co. Kg Method for configuring a fluid control unit, computer program product and fluidic system
US20150059749A1 (en) * 2012-04-02 2015-03-05 Metran Co., Ltd. Pump unit and respiratory assistance device
US20160186930A1 (en) * 2014-02-28 2016-06-30 Praxair Technology, Inc. Pressurized product stream delivery
WO2018192780A1 (en) * 2017-04-19 2018-10-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Liquefied gas supply spare system and liquefied gas spare supply method
CN110651151A (zh) * 2017-04-19 2020-01-03 乔治洛德方法研究和开发液化空气有限公司 液化气体供应备用系统和液化气体备用供应方法
CN108591041A (zh) * 2018-07-06 2018-09-28 华能国际电力股份有限公司 给水泵最小流量再循环阀控制系统及方法
EP3699534A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
EP3699535A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
CN116951800A (zh) * 2023-09-15 2023-10-27 广东美的暖通设备有限公司 控制方法、控制装置、双循环制冷系统及存储介质

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ATE467763T1 (de) 2010-05-15
EP2060788B1 (de) 2010-05-12
DE502007003785D1 (de) 2010-06-24
EP2060788A1 (de) 2009-05-20

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