KR101135685B1 - Control method of Organic Rankine Cycle System Pump - Google Patents

Abstract

The present invention is a heat exchanger 130 for heating the liquid refrigerant in a high-temperature, high-pressure gas state, the power generation unit 140 for producing electricity by expanding the high-temperature high-pressure refrigerant to low temperature low pressure, and the power generation unit 140 In the ORC system pump control method consisting of a condenser 150 for cooling the refrigerant of the gas state in the liquid state and a pump 120 for continuously circulating the refrigerant of the condenser 150 in the rear end, the heat exchange unit 130 Is composed of a preheater 133, evaporator 135, superheater 137, by installing a flow meter 170 between the pump 120 and the preheater 133 to simultaneously measure the pump rotation speed and flow rate data, the pump When the steam occurs in the 120 to install a steam vent tube 121 between the pump 120 and the condensation tank 110 to eject it, the valve for controlling the flow rate of steam vent flow on the steam vent tube 121 (123) ), And the steam is pumped on the steam vent tube 121 (120) relates to a pump control system ORC characterized in that the installation of observation path 125) to confirm whether to pass through the condensing tank 110.

Description

OCC system pump control method {Control method of Organic Rankine Cycle System Pump}

The present invention relates to an ORC system pump control method, and more particularly, by installing a flow meter between a pump and a preheater to simultaneously measure pump rotation speed and flow rate data, and condensate with the pump to eject steam when the pump is generated. A steam vent tube is installed between the tanks, and a valve for adjusting the flow rate of the steam vent is installed on the steam vent tube, and an observation mirror is installed on the steam vent tube to check whether steam is discharged from the pump to the condensation tank. The present invention relates to an ORC system pump control method.

In general, the ORC (Organic Rankine Cycle) turbo generation system structure, as shown in Figure 1, the cycle consists of the evaporator 10, turbine 20, condenser 30 and pump 40, Among them, a preheater 11 and a superheater 12 are provided at the front and rear of the evaporator 10, respectively, and a condensation tank 35 for storing condensate is provided at the rear of the condenser 30. A separate flowmeter may be further provided to measure the flow rate of the refrigerant in the liquid state after 35).

To overcome the disadvantages of using steam media for heat transfer or for waste heat recovery and for power generation, hot organic working fluids have been introduced in the powder plant as working fluids and as working and heat transfer intermediates. Thermo-energy converters based on a thermodynamic Organic Rankin Cycle, or similar heat-energy transfer system, are particularly versatile sources of power to produce power from hundreds of watts (W) to tens of megawatts (MW). Useful for remote heat recovery and power generation from, for example, gas turbine emissions, combustion of conventional fuels, combustion of biomass fuels, geothermal sources, solar collectors and waste heat produced in power plants and other industrial processes. Do. Organic fluids that can be maintained at temperatures as high as about 350 ° C. are more beneficial than water vapor, and low condensation temperatures and high temperatures may be limited by the use of steam to form droplets outside of the turbine due to expansion of the steam, which may cause corrosion of the turbine blades. Turbine expansion rates can also be used successfully in power generation cycles. Because of the nature of organic fluids, they have the property of overheating (or drying) during the expansion process to prevent the formation of droplets as in the case of using steam.

Such an organic Rankine cycle is a Rankine cycle that uses an organic medium as a working fluid, so that electricity can be generated by recovering a heat source in a relatively low temperature range (60 to 200 ° C.). The organic Rankine cycle uses a Freon-based refrigerant having a low boiling point and a high evaporation pressure as a working fluid due to a system characteristic of producing a high pressure gas at a low temperature to drive a turbine.

Since the refrigerant of the Freon series has a very high evaporation characteristic, it is distinguished from the existing Rankine cycle that uses water as a working fluid in a pump and various heat exchanger control methods.

Such an organic Rankine cycle operates a high speed turbine at a turbine inlet temperature of about 100 ° C., which is lower than that of a conventional Rankine cycle. When the cycle control is not smooth, the operation is unstable. there was.

The working fluid used in the conventional Rankine cycle as described above is used in the refrigerant of the Freon series is very high evaporation characteristics. Therefore, the steam generation rate is increased due to the cavitation (cavitation) effect when the friction with the rotary blades of the pump. Therefore, if a certain amount of steam is generated after a certain period of time after the pump is running, the pump may run out of water and thus may not supply the refrigerant to the preheater.

An object of the present invention for solving the problems of the prior art is to improve the low-temperature operating characteristics of the working fluid to increase the power generation efficiency of the turbine, to prevent excessive operation of the turbine, and also stable operation of the ORC system pump control method In providing.

In addition, another object of the present invention is to install a flow meter between the pump and the preheater to measure the pump rotation speed and flow rate data at the same time, the steam vent tube is installed between the pump and the condensation tank in order to eject the steam generated in the pump And installing a valve for controlling the flow rate of the steam vent on the steam vent tube, and providing an ORC system pump control method for installing an observation mirror on the steam vent tube to check whether the steam escapes from the pump to the condensation tank. have.

An object of the present invention described above is a heat exchanger 130 for heating a refrigerant in a liquid state to a high-temperature, high-pressure gas state, and a power generation unit 140 for producing electricity by expanding a high-temperature and high-pressure refrigerant to low temperature and low pressure; In the ORC system pump control method consisting of a condenser 150 for cooling the refrigerant in the gas state in the liquid state at the rear end of the power generation unit 140 and a pump 120 for continuously circulating the refrigerant in the condenser 150, the heat exchange The unit 130 includes a preheater 133, an evaporator 135, and a superheater 137, and installs a flow meter 170 between the pump 120 and the preheater 133 to simultaneously measure the pump rotation speed and the flow rate data. However, when the steam occurs in the pump 120, a steam vent tube 121 is installed between the pump 120 and the condensation tank 110 to eject it, and the steam vent flow rate on the steam vent tube 121 Install the control valve 123, the steam vent tube 121 The vapor may be achieved in the pump 120 through the ORC system, pump control method characterized in that the installation of observation path 125) to confirm whether to pass through the condensing tank 110.

Here, the preheater 133 receives the refrigerant from the pump 120 to increase the temperature to the target temperature through the heat source, and determines whether the target temperature is reached by measuring the temperature of the refrigerant passing through the preheater 133. When the temperature is below or exceeds the temperature, the heat source supply amount of the heat source supply unit 131 is controlled.

And, the specification of the preheater 133 is refrigerant inlet temperature, pressure: 30 ℃, 7.3bar; Refrigerant outlet temperature, pressure: 77 ° C., 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: characterized in that designed to 0.06kg / s.

Here, the evaporator 135 receives the refrigerant that has been heated up from the preheater 133 and controls the working fluid temperature by controlling the heat source flow rate in the heat source supply unit 131 so that the liquid and gas coexist, and the evaporator 135 The level of the liquid level is always measured using a level sensor, and if the liquid level is low, the rotational speed of the pump 120 is increased, and vice versa, the rotational speed of the pump 120 is lowered so that the liquid level in the evaporator 135 is reduced. It is characterized in that the liquid and gas always coexist constantly.

And, the specification of the evaporator 135, refrigerant inlet temperature, pressure: 77 ℃ (liquid), 7.3 bar; Refrigerant outlet temperature, pressure: 77 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: characterized in that designed to 0.14kg / s.

Here, the superheater 137 is installed at the rear end of the evaporator to receive the refrigerant, and control the temperature of the refrigerant at the rear end of the superheater 137 by controlling the flow rate of the heat source of the heat source supply unit 131 according to the state of the refrigerant temperature. .

And, the specification of the superheater 137 is the refrigerant inlet temperature, pressure: 77 ℃ (gas), 7.3bar; Refrigerant outlet temperature, pressure: 87 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. water saturated steam; Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: characterized in that designed to 0.01kg / s.

Here, the power generation unit 140 is characterized in that the turbine 143 is rotated by receiving the superheated steam in which the constant pressure heating is performed by the superheater 137 to rotate the shaft of the generator 145 to generate power.

At this time, the power generation unit 140 is characterized in that the operation without the drive of the turbine 143 by using the bypass pipe 141 until the operating fluid state is normal at the beginning of the system operation.

The condenser 150 is installed at the rear end of the turbine 143 to be liquefied by receiving a working fluid in a vapor state, and is connected to the cooling tower 160.

Here, the specification of the condenser 150, refrigerant inlet temperature, pressure: 56 ℃ (gas), 1.8ba; Refrigerant outlet temperature, pressure: 30 ° C. (liquid), 1.8 bar; Refrigerant flow rate: 1.9 kg / s; Cooling water inlet temperature: 20 ° C. (water); Cooling water outlet temperature: 25 ° C. (water); Heat source flow rate: characterized in that designed to 19.3kg / s.

The condenser tank 110 may be installed at a rear end of the condenser 150 to store a liquid refrigerant.

Here, the bypass line 121 is installed in order to prevent the pump 120 from being vanished due to friction between the blades of the pump 120 and the refrigerant, thereby condensing the refrigerant vapor 110. It characterized in that the discharge to.

ORC system pump control method of the present invention according to the above configuration has the effect of improving the low-temperature operating characteristics of the working fluid to increase the power generation efficiency of the turbine, and prevent the excessive operation of the turbine, and stable operation.

In addition, in the present invention, a flowmeter is installed at the rear end of the condenser, and a flowmeter parallel pipe of the same size is installed in parallel with the pipe in which the condenser is installed, and a valve capable of ON / OFF control is provided in the flowmeter parallel pipe installed in parallel with the flowmeter. By installing the system, by closing the parallel pipe side valve during operation of the system and allowing the working fluid to flow only through the flowmeter, the flow rate is measured, thereby improving the turbine efficiency.

1 is a schematic view showing an organic Rankine cycle of the prior art.
Figure 2 is a schematic diagram illustrating an ORC system pump control method according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As an embodiment of the present invention with reference to the drawings, the main system specification and control method for a 30kW-class ORC power generation system will be described.

In this case, when the output of the illustrated system is different, it is necessary to change the flow rate of the working fluid, the flow rate of the supply heat source, and the size of the turbine accordingly, and the rest of the control method is performed in the same manner.

The system includes a heat exchanger 130 for heating a liquid refrigerant into a gaseous state of high temperature and high pressure, a power generation unit 140 for generating electricity by expanding a high temperature and high pressure refrigerant to low temperature and low pressure, and a power generation unit 140. ) Condenser 150 for cooling the gaseous refrigerant in the liquid state at the rear end, and a pump 120 for continuously circulating the refrigerant of the condenser 150.

Here, the heat exchanger 130 is composed of a preheater 133, an evaporator 135, and a superheater 137.

The preheater 133 will be described below. The preheater 133 serves to increase the temperature to the target temperature through the heat source by receiving the refrigerant from the pump 120. At this time, it is determined whether the target temperature is reached by measuring the temperature of the refrigerant passing through the preheater 133, and when the temperature reaches or exceeds the target temperature, the heat source supply amount of the heat source supply unit 131 is controlled.

Specifications of this preheater 133 are refrigerant inlet temperature, pressure: 30 ° C., 7.3 bar; Refrigerant outlet temperature, pressure: 77 ° C., 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); The heat source flow rate is preferably designed to be 0.06kg / s.

Next, the evaporator 135 will be described. The evaporator 135 controls the working fluid temperature by controlling the heat source flow rate in the heat source supply unit 131 so that the liquid and gas coexist by receiving the refrigerant that has been heated by the preheater 133.

At this time, the level of the liquid level of the evaporator 135 is always measured using a level sensor, and if the liquid level is low, the rotation speed of the pump 120 is increased, and vice versa. Lowering so that the liquid and gas always co-exist in the evaporator 135 at all times.

The reason for this is that the pressure and the saturation pressure at the temperature can be controlled through the temperature control only when the liquid and the gas coexist.

Specifications of the evaporator 135 are refrigerant inlet temperature, pressure: 77 ° C. (liquid), 7.3 bar; Refrigerant outlet temperature, pressure: 77 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: It is preferable to design at 0.14 kg / s.

Next, the superheater 137 will be described. The superheater 137 receives a working fluid (refrigerant vapor) from the evaporator 135.

This, the superheater 137 serves to prevent the refrigerant vapor generated in the evaporator 135 is condensed while going to the turbine 143 to lower the turbine efficiency.

The superheater 137 controls the heat source flow rate of the heat source supply unit 131 according to the state of the refrigerant temperature at the rear end of the superheater 137 in the same way as the evaporator 135 and the preheater 133, and thus the refrigerant temperature at the rear end of the superheater 137. To control.

Specifications of the superheater 137 are refrigerant inlet temperature, pressure: 77 ° C. (gas), 7.3 bar; Refrigerant outlet temperature, pressure: 87 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. water saturated steam; Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate can be designed as 0.01kg / s.

Next, the power generation unit 140 will be described. The power generation unit 140 is composed of a turbine 143 and the generator 145.

The turbine 143 is rotated by receiving the superheated steam in which the constant pressure heating is performed by the superheater 137, thereby rotating the shaft of the generator 145 to generate power.

At this time, since the operating fluid state is not the normal state at the beginning of the system operation, it may give a strain to the driving of the turbine 143. Therefore, it is preferable to utilize the bypass pipe 121 to operate without driving the turbine 143 until the system reaches a steady state.

Next, the condenser 150 will be described. The condenser 150 is installed at the rear end of the turbine 143 and serves to liquefy by receiving a working fluid in a vapor state. The cooling tower 160 may be configured separately.

The specifications of the condenser 150 are refrigerant inlet temperature, pressure: 56 ° C. (gas), 1.8 ba; Refrigerant outlet temperature, pressure: 30 ° C. (liquid), 1.8 bar; Refrigerant flow rate: 1.9 kg / s; Cooling water inlet temperature: 20 ° C. (water); Cooling water outlet temperature: 25 ° C. (water); Heat source flow rate: can be designed as 19.3kg / s.

Then, a condensation tank 110 for storing the liquid refrigerant at the rear end of the condenser 150 is installed. The condensation tank 110 is a tank capable of storing 300 liters of liquid refrigerant, and injects 300 liters of the liquid refrigerant R245fa into the condensation tank.

In addition, a pump 120 is installed at the rear end of the condenser. The pump 120 serves to supply the working fluid from the low pressure state to the high pressure state.

The working fluid of the ORC system pump control method of the present invention has a maximum pressure equal to the evaporation pressure in the evaporator 135.

Therefore, a pump 120 capable of raising the pressure by the pressure difference from the condensation pressure to the evaporation pressure and simultaneously supplying a working fluid flow rate that meets the system specifications is used.

The pump 120 is operated to send the coolant to the preheater 133. A part of the coolant may be vaporized due to friction between the blades of the pump 120 and the coolant. have.

In order to solve this problem, as shown in FIG. 2, a bypass line 121 may be installed to discharge the refrigerant vapor to the condensation tank 110 to remove the steam.

ORC system pump control method of the present invention according to the above configuration has the advantage that the low temperature operating characteristics of the working fluid can be improved to increase the power generation efficiency of the turbine, prevent excessive operation of the turbine, and also stable operation.

In addition, the present invention, as shown in Figure 2 when the pump 120 is operating normally produces a constant flow rate performance in accordance with the rotational speed.

Thus, a flow meter 170 is installed between the pump 120 and the preheater 133 to simultaneously measure the pump rotation speed and the flow rate data.

In addition, a steam vent tube 121 is installed between the pump 120 and the condensation tank 110 in order to eject the steam when the pump 120 is generated, and the steam vent flow rate on the steam vent tube 121. Install the adjusting valve 123.

At this time, an observation mirror 125 is installed on the steam vent tube 121 to check whether the steam escapes from the pump 120 to the condensation tank 110.

Here, it is observed that when a lot of refrigerant vapor occurs in the pump 120, the flow rate measured by the flow meter 170 is reduced compared to the rotation speed of the pump 120.

In this case, the steam vent valve 123 is opened to discharge steam.

Then, as a result of confirming through the steam observation mirror 125, if the vapor discharge is very small or no close the steam vent valve 123.

In this case, when the steam vent valve 123 is opened, the refrigerant in the liquid state together with the steam does not flow toward the preheater 133, but is recovered to the condensation tank 110, thereby reducing the refrigerant circulation flow rate.

In this case, the number of rotations of the pump 120 should be higher, and in this case, the energy consumption of the pump 120 is increased to decrease the cycle efficiency.

Therefore, the steam vent valve 123 is controlled in conjunction with the steam flow rate data measured through the steam observation mirror 125 and the like through the PID control.

In the above described a preferred embodiment of the present invention, but described in the claims and detailed description of the present invention as well as the embodiment of the present invention simply applied in combination with the known art of the present invention to those skilled in the art It is to be understood that the description of the degree to which the present invention can be simply modified is included in the technical scope of the present invention.

110: condensation tank
120: pump
121: steam vent tube
123: steam vent valve
125: steam observation mirror
130: heat exchanger
131: heat source supply unit
133: preheater
135: evaporator
137: superheater
140: power generation unit
141: bypass line
143: turbine
145: generator
150: condenser
160: cooling tower
170: flow meter

Claims (13)

Heat exchanger 130 for heating the refrigerant in the liquid state to a high-temperature, high-pressure gas state, the power generation unit 140 for producing electricity by expanding the high-temperature high-pressure refrigerant to low temperature low pressure, and in the rear end of the power generation unit 140 In the ORC system pump control method comprising a condenser 150 for cooling a refrigerant in a gas state and a pump 120 for continuously circulating a refrigerant in the condenser 150, the heat exchange unit 130 is a preheater ( 133, the evaporator 135, the superheater 137, the flow rate 170 is installed between the pump 120 and the preheater 133 to measure the pump rotation speed and flow rate data at the same time, the pump 120 Steam vent tube 121 is installed between the pump 120 and the condensation tank 110, and a steam vent flow rate control valve 123 is installed on the steam vent tube 121 to eject the steam when the steam is generated. And, the steam on the steam vent tube 121 in the pump 120 ORC system pump control method, characterized in that the installation of the observation mirror (125) to determine whether the exit to the condensation tank (110).
The method of claim 1,
The preheater 133 receives the refrigerant from the pump 120 to increase the temperature to the target temperature through the heat source, and determines whether the target temperature is reached by measuring the temperature of the refrigerant passing through the preheater 133 and reaching the target temperature. If less than or exceeds, ORC system pump control method characterized in that for controlling the heat source supply amount of the heat source supply unit (131).
The method of claim 2,
Specifications of the preheater 133 are refrigerant inlet temperature, pressure: 30 ° C., 7.3 bar; Refrigerant outlet temperature, pressure: 77 ° C., 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: ORC system pump control method characterized in that designed to 0.06kg / s.
The method of claim 1,
The evaporator 135 receives the refrigerant that has been heated up from the preheater 133 to control the working fluid temperature by controlling the heat source flow rate in the heat source supply unit 131 so that the liquid and gas coexist, and the liquid of the evaporator 135 The level sensor is used to measure whether there is always a certain level, and if the liquid level is low, the rotation speed of the pump 120 is increased, and vice versa, the rotation speed of the pump 120 is lowered. ORC system pump control method, characterized in that the gas always coexist constantly.
The method of claim 4, wherein
Specifications of the evaporator 135 are refrigerant inlet temperature, pressure: 77 ° C. (liquid), 7.3 bar; Refrigerant outlet temperature, pressure: 77 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. (saturated water vapor); Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: ORC system pump control method characterized in that designed to 0.14kg / s.
The method of claim 1,
The superheater 137 is installed in the rear end of the evaporator is supplied with the refrigerant, the ORC system characterized in that to control the refrigerant temperature of the rear end of the superheater 137 by controlling the flow rate of the heat source of the heat source supply unit 131 according to the state of the refrigerant temperature. Pump control method.
The method of claim 6,
Specifications of the superheater 137 are refrigerant inlet temperature, pressure: 77 ° C. (gas), 7.3 bar; Refrigerant outlet temperature, pressure: 87 ° C. (gas), 7.3 bar; Refrigerant flow rate: 1.9 kg / s; Heat source inlet temperature: 140 ° C. water saturated steam; Heat source outlet temperature: 140 ° C. (water condensate); Heat source flow rate: ORC system pump control method characterized in that designed to 0.01kg / s.
The method of claim 1,
The power generation unit 140 receives the superheated steam that is subjected to the constant pressure heating from the superheater 137, the turbine 143 is rotated to rotate the shaft of the generator 145 to generate power is ORC system pump control method .
The method of claim 8,
The power generation unit 140 is an ORC system pump control method, characterized in that the operating fluid by using the bypass pipe (141) until the operating fluid is normal at the beginning of the system operation without the drive of the turbine (143).
The method of claim 1,
The condenser 150 is installed on the rear end of the turbine (143) to be supplied with a working fluid in the vapor state to liquefy, but is connected to the cooling tower 160, ORC system pump control method.
The method of claim 10,
Specifications of the condenser 150, refrigerant inlet temperature, pressure: 56 ℃ (gas), 1.8ba; Refrigerant outlet temperature, pressure: 30 ° C. (liquid), 1.8 bar; Refrigerant flow rate: 1.9 kg / s; Cooling water inlet temperature: 20 ° C. (water); Cooling water outlet temperature: 25 ° C. (water); Heat source flow rate: ORC system pump control method characterized in that designed to 19.3kg / s.
The method of claim 11,
ORC system pump control method, characterized in that the condenser tank (110) for storing the liquid refrigerant in the rear end of the condenser (150) is installed.
The method of claim 1,
Friction between the blades of the pump 120 and the refrigerant causes a portion of the refrigerant to vaporize, thereby installing a bypass line 121 to discharge the refrigerant vapor to the condensation tank 110. ORC system pump control method, characterized in that.

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