• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    It is an efficient pump anti-cavitation system for organic rankine power cycles, consisting of the optimization of the positive net height (or npsh) available to the suction of the pump (4) of the cycle. In this way, the operation of the pump (4) is improved, its useful life is lengthened and the energy efficiency of the power cycle is increased. For this, a series of sensors (7, 8, 9) and a control system (6) are required that compare the needs of the pump with the instantaneous operating conditions and that by means of actuators (5) optimize the operation of the power cycle. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2586425A2
    申请号:ES201530204
    申请日:2015-02-19
    公开日:2016-10-14
    发明作者:Roberto Collado Puig；Manuel GONZÁLEZ PIQUER；Jose Pascual MARTÍ MATA；Joaquín Navarro Esbrí
    申请人:Expander Tech S L；Expander Tech Sl；
    IPC主号:
    专利说明:

    EFFICIENT PUMP ANTI-CAVITATION SYSTEM FOR CYCLES OFORGANIC RANKINE POWER
    SECTOR OF THE TECHNIQUE
    The present invention is directed to improve the operation, extend the useful life and increase
    10 the energy efficiency of power cycles based on the Rankine thermodynamic cycle. Specifically, it is a positive net height optimization system (commonly known by its acronym in English NPSH, Net Positive Suction Head) available in the cycle pump. In this way, cavitation of the pump is avoided and the performance of the power cycle is improved.
    BACKGROUND OF THE INVENTION
    The Rankine steam power cycle is the main generation system used in power plants. However, its application in low temperature sources does not present 20 satisfactory energy efficiencies. That is why a similar power cycle was developed, but it uses more volatile work fluids than water to improve efficiency in low temperature applications, such as solar thermal, geothermal, biomass, waste heat or others. This is the Organic Rankine Cycle (ORC). Its principle of operation consists in evaporating the organic work fluid by means of the thermal energy of the source and expanding the steam to generate mechanical work, which in turn is converted into electricity by means of an electric generator. It is a closed cycle, in which the steam from the expander outlet is condensed and pressurized by means of a pump to evaporate again and restart the cycle. It is, therefore, a simple and efficient way to take advantage of renewable or residual thermal energy to
    30 produce electricity.
    In this type of power cycles the pump plays a fundamental role. It is the element in charge of supplying the pressure required by the system, but it also usually contributes to its control, providing stability and smooth operation. However, the organic working fluid used, as already mentioned above, is very volatile and very easy to evaporate at low temperature. So much so, that this


    It can occur spontaneously in the suction of the pump, since it is the point of lowest pressure and temperature of the cycle, causing the appearance of bubbles and cavitation of the pump. When this occurs, the process becomes unstable and the life of the pump is significantly reduced. For the purpose of solving it, a heat exchanger can be introduced to the aspiration of the ORC pump, known as a sub-cooler, and a reservoir to dampen pressure fluctuations and ensure a minimum static pressure, as shown in Fig. 1 . However, when the ORC works at different loads the operating conditions are altered, obtaining a lack or excess of available NPSH that causes cavitation or the significant reduction of the energy efficiency of the cycle, respectively. In this sense, the proposed invention allows the optimization of the NPSH available depending on the instantaneous demands of the pump, preventing cavitation and improving the efficiency of the cycle.
    EXPLANATION OF THE INVENTION
    The invention consists in the conditioning of the available NPSH (static pressure and subcooling) to the suction of the pump, according to the instantaneous requirements or NPSH required. For this, a control system is required that compares the needs of the pump with the instantaneous operating conditions and acts with the objective of optimizing the operation.
    The pump needs are obtained from the required NPSH curve of the specific pump used (information obtained from the pump manufacturer). This curve is implemented in a control system, which from the measurements (temperatures, flow, pressures, etc.) provides the minimum NPSH value required to avoid cavitation. On the other hand, the available NPSH can be calculated as the difference between the saturation pressure of the working fluid (at the conditions of the inlet temperature at the pump) and the pressure measured at the suction. Thus, it must be fulfilled that the available NPSH is always greater than that required to avoid cavitation, but without reaching a large difference that impairs efficiency. To maintain this, the system is operated by modifying the condensation conditions by varying the flow rate of the secondary fluid of the condenser, usually air, water or water with glycol. Thus, reducing said flow increases the operating conditions of the condensation (pressure and temperature), improving the efficiency of the sub-cooler and increasing the degree of sub-cooling or NPSH available. On the contrary, the reduction of the flow will reduce this sub-cooling to the optimum values to avoid cavitation and not sacrifice efficiency. The method of


    Control of said flow variation depends on the type of condenser used. Thus, an air condenser (aero condenser, closed cooling towers, closed adiabatic condensers, etc.) can vary the speed of rotation of the fans, reducing it to increase the NPSH available in the pump and vice versa. A water condenser (open cooling tower, liquid coolers, etc.) can reduce the flow rate for example with a frequency converter in the pump.
    In this exposed case, the variation of the secondary fluid flow rate in the condenser is contemplated, while the secondary fluid flow rate in the subcooler is kept to the maximum (without control). But in the case of excessive subcooling, even with the maximum flow entering the condenser, the same principle can be extended to the subcooler, reducing the secondary fluid flow and thus the available NPSH to optimum values.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Fig. 1 shows the basic scheme of the ORC components. The components to be treated in the patent are:
    one. Condenser.
    2. Deposit.
    3. Sub Cooler
    Four. Bomb.
    Fig. 2 focuses on the invention using air as a secondary fluid to dissipate heat from the condenser and subcooler. In this case, the actuator is placed in the condenser, regulating the air intake. The scheme consists of the following parts:
    one. Condenser.
    2. Deposit.
    3. Sub Cooler
    Four. Bomb.
    5. Variable frequency drive, or the acronym AFD.
    6. Control system.
    7. Pressure transmitter.
    8. Temperature probe
    9. Flow transmitter (flow meter, frequency inverter or others).


    Fig. 3 focuses on the invention using air as a secondary fluid to dissipate heat from the condenser and subcooler. In this case the actuator is located both in the condenser and in the sub-cooler. The scheme consists of the following parts:
    one. Condenser.
    2. Deposit.
    3. Sub Cooler
    Four. Bomb.
    5. Variable frequency One for the condenser and one for the subcooler.
    6. Control system.
    7. Pressure transmitter.
    8. Temperature probe
    9. Flow transmitter (flow meter or frequency inverter).
    Fig. 4 focuses on the invention using liquid as a secondary fluid, to dissipate heat from the condenser and subcooler. In this case the actuator is placed in the condenser, regulating the liquid inlet. The scheme consists of the following parts:
    one. Condenser.
    2. Deposit.
    3. Sub Cooler
    Four. Bomb.
    5. Actuator to regulate the flow (for example, motorized or pneumatic three-way valve).
    6. Control system.
    7. Pressure transmitter.
    8. Temperature probe
    9. Flow transmitter (flow meter or frequency inverter).
    Fig. 5 focuses on the invention using liquid as a secondary fluid, to dissipate heat from the condenser and subcooler. In this case the actuator is located both in the condenser and in the sub-cooler. The scheme consists of the following parts:
    one. Condenser.
    2. Deposit.
    3. Sub Cooler
    Four. Bomb.
    5. Actuator to regulate the flow rate (for example, motorized three-way valve or


    pneumatics). One for the condenser and one for the subcooler.
    6. Control system.
    7. Pressure transmitter.
    8. Temperature probe
    5 9. Flow transmitter (flow meter or frequency inverter).
    PREFERRED EMBODIMENT OF THE INVENTION
    The invention can be carried out in any application with ORC, by selecting the
    10 scheme used depending on whether the secondary fluid, to dissipate heat from the condenser and the subcooler, is air or liquid. The embodiment of the invention can be described as follows:
     Temperature probe (8). It must be placed to the suction of the pump, to know the instantaneous temperature. This temperature will be used by the control system to obtain the saturation pressure corresponding to the organic working fluid
    used.
     Pressure transmitter (7). It must be placed to the suction of the pump, to know the instantaneous pressure. The measured pressure will be compared, by the control system, with the saturation pressure corresponding to the temperature measured in the
    20 aspiration, obtaining the available NPSH.  Measurement of pump working conditions (9). To obtain the NPSH required by the pump there are different alternatives: measure the flow rate transferred by the pump using a flowmeter, know the speed of rotation using a frequency converter (measuring the hertz and knowing the nominal speed of the motor
    25 the pump) or by means of the power consumed by the pump or others. In all cases, the “NPSH-pump conditions” curve must be implemented in the control system.
     Control system (6). This system must have the required NPSH curve of the concrete pump used implemented. This curve can be a function of the 30 measured parameters of pump operation (flow, revolutions, etc.). An equation or curve must also be implemented to obtain the saturation pressure of the organic working fluid at the temperature measured at the pump's suction. You must make the comparison between the pump requirements (NPSH required) and the instantaneous working conditions (NPSH available) and act as
    35 so that the available NPSH is slightly greater than the required NPSH.


     Frequency inverter (5). The drives allow to control the speed of the fans depending on the output of the control system.
     Three-way valve or other type of automatic actuators (5) to regulate the secondary fluid flow depending on the output of the control system.

    权利要求:
    Claims (2)
    [1]
    1. Efficient pump anti-cavitation system for organic Rankine power cycles. Consisting of the following components:
    (one) Condenser. It is the heat exchanger responsible for yielding the latent heat of the organic fluid. It is positioned at the exit of the expander and inlet of the tank (2). As a secondary fluid you can use both air and liquid.
    (2)  Deposit. Closed container located at the condenser outlet (1) and sub-cooler inlet (3).
    (3)  Sub Cooler It is the heat exchanger responsible for transferring the sensible heat of the organic fluid, obtaining sub-cooled liquid. It is positioned at the outlet of the tank (2) and the pump inlet (4). As a secondary fluid you can use both air and liquid.
    (4) Bomb. It is the element responsible for providing the pressure and flow required by the system. It is positioned at the outlet of the subcooler (3) and evaporator inlet.
    (5) Frequency inverters that control the motors of the condenser fans (1) and the subcooler (3) by air. Or in the case of liquid as a secondary fluid, (Fig. 5) three-way valves electrically or pneumatically motorized.
    (6) Control system. System that uses the inputs or measurements of the system (temperature, pressure, flow, frequency, power, etc.) (7) (8) (9) together with the algorithms implemented (NPSH curve of the pump, saturation pressure of the organic fluid of work, difference between NPSH available and required) to optimize the control of the outputs (supply to the frequency inverters and three-way valves or liquid flow actuators) (5).
    (7)  Pressure transmitter. Placed to the suction of the pump (4).
    (8)  Temperature probe Placed to the suction of the pump (4).
    (9) Pump operation transmitter (4). Some of the alternatives are: measurement of the back flow, measurement of the speed of rotation of the pump using a frequency inverter, measurement of the differential pressure, measurement of the power consumed, or others.
    [2]
    2. Operational procedure of the efficient anti-cavitation system pumps for organic Rankine power cycles, defined according to claim 1. Perform the following steps:

    Obtaining the available NPSH: Measuring the suction pressure of the pump (4) using a pressure transmitter (7). Measuring the suction temperature of the pump (4) using a probe
    5 temperature (8). Calculation of saturation pressure from the suction temperature, depending on the properties of the organic working fluid, using an algorithm implemented in the control system (6).
    Obtaining the required NPSH:
    10 Measurement of the working conditions of the pump (4) using its operating transmitter (9). Some alternatives are: measurement of the back flow, measurement of the speed of rotation of the pump using a frequency inverter, measurement of differential pressure, measurement of the power consumed or others.
    15 Calculation of the NPSH required by the pump (4) from the operating conditions of the pump (4) (flow, turns or power) using an algorithm implemented in the control system (6).
    Control and optimization of the parameters of interest: Compare the required NPSH calculated and the available NPSH calculated using a
    20 PID control system (Proportional Integral and Derivative). Optimize the operating instructions of the frequency inverters and valves with electric or pneumatic motor (or actuators to regulate the flow of liquid) (5) to avoid cavitation phenomena and operate with high efficiency. Act on the frequency inverters (which feed the motors of the
    25 condenser and subcooler by air) or three-way valve type actuators (5).

    Fig. 1. Basic scheme of the Organic Rankine cycle
    Fig. 2 Efficient anti-cavitation system controlling the air flow entering the condenser
    6
    Fig. 3 Efficient anti-cavitation system controlling the flow of air entering the condenser and the subcooler.

    6
    5
    Fig. 4 Efficient anti-cavitation system controlling the flow of liquid entering the condenser.
    6
    5
    Fig. 5 Efficient anti-cavitation system controlling the flow of liquid entering the condenser and the subcooler.
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    引用文献:
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    CN111946671A|2020-08-20|2020-11-17|福建蓝海节能科技有限公司|Method for effectively preventing cavitation of water pump|JPS61235796A|1985-04-12|1986-10-21|Hitachi Ltd|Recirculation pump cavitation preventive device|
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    US6663349B1|2001-03-02|2003-12-16|Reliance Electric Technologies, Llc|System and method for controlling pump cavitation and blockage|
    JP2010084697A|2008-10-01|2010-04-15|Sayama Seisakusho:Kk|Pump cavitation-free control device and pump cavitation-free control method|
    DE102009053390B3|2009-11-14|2011-06-01|Orcan Energy Gmbh|Thermodynamic machine and method for its operation|
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    法律状态:
    2015-07-06| PC2A| Transfer of patent|Owner name: EXPANDER TECH, S.L. Effective date: 20150630 |
    2018-06-08| FG2A| Definitive protection|Ref document number: 2586425 Country of ref document: ES Kind code of ref document: B1 Effective date: 20180608 |
    2021-10-01| FD2A| Announcement of lapse in spain|Effective date: 20211001 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES201530204A|ES2586425B1|2015-02-19|2015-02-19|EFFICIENT PUMP ANTI-CAVITATION SYSTEM FOR ORGANIC RANKINE POWER CYCLES|ES201530204A| ES2586425B1|2015-02-19|2015-02-19|EFFICIENT PUMP ANTI-CAVITATION SYSTEM FOR ORGANIC RANKINE POWER CYCLES|
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