JP5192736B2 - Exhaust heat power generation apparatus, operation method of exhaust heat power generation apparatus - Google Patents

Description

  The present invention relates to an exhaust heat power generation apparatus that converts thermal energy of an exhaust heat source into electrical energy, and more particularly to an exhaust heat power generation apparatus that generates power using low-temperature exhaust heat as a heat source, and a method for operating the exhaust heat power generation apparatus.

  In recent years, effective use of exhaust heat from an exhaust heat source has been promoted by various methods because of the need for energy saving promotion. However, high-temperature or large-capacity exhaust heat that is easy to use effectively is almost completely used, and even in newly installed equipment, the temperature of exhaust heat exhausted tends to decrease as a result of progress in energy saving. It is in. Therefore, in order to further promote energy saving, it is indispensable to effectively use low-temperature and small-capacity exhaust heat.

  FIG. 1 is a diagram showing a configuration example of this type of conventional exhaust heat power generation apparatus. The exhaust heat power generation apparatus is an exhaust heat power generation apparatus that includes the power generation apparatus 100 and generates electric power using hot water of about 80 ° C. from the exhaust heat source 120 as a heat source and cooling water cooled by the cooling tower 130 as a low temperature heat source. A power generator 100 includes a steam generator 101, a droplet separator 102, a regulator valve (not shown) and a main steam valve 103, a turbine 104 as an expander, a turbine generator 106 having a high-speed generator 105, and a condenser. 107, a liquid supply pump 108 is provided, and these are connected by a working medium pipe 109. The power generator 100 is controlled by a control panel 110, and AC power generated by the high-speed generator 105 is converted into DC power by a high-frequency rectifier 111, and further AC power (generally commercial power of 50 Hz or 60 Hz) by a system linkage device 112. Is transmitted to the grid 113. Although an example in which a turbine is used as an expander is shown here, the working medium steam from the steam generator 101 is expanded to obtain a mechanical rotational force, and the high-speed generator 105 is rotationally driven by the rotational force. Any machine can be used.

  By supplying hot water from the exhaust heat source 120 to the steam generator 101 by the hot water circulation pump 121, the working medium liquid supplied to the steam generator 101 by the liquid supply pump 108 is heated and becomes working medium vapor. The droplets are supplied to the droplet separator 102 through the pipe 109, and the droplets in the working medium vapor are separated and removed by the droplet separator 102. The working medium vapor from which the liquid droplets have been removed is supplied to a turbine 104 as an expander through a regulator valve (not shown) and a main steam valve 103, and the high-speed generator 105 is driven by the rotational force of the turbine 104. Rotate. The working medium vapor discharged from the turbine 104 is supplied to the condenser 107, cooled by the cooling water supplied from the cooling tower 130 by the cooling water pump 131 by the condenser 107, and condensed to become a working medium liquid. The working medium liquid is sent to the steam generator 101 by the feed pump 108, and the working medium circulates. The exhaust heat power generation equipment uses exhaust gas from the exhaust heat source as a heat source instead of hot water, and the low temperature heat source is not a combination of cooling water and a cooling tower, but is cooled by air (air-cooled condenser) or river water. Some use other low-temperature heat sources. Some use a secondary fluid that exchanges heat with the low-temperature heat source, or use another technique equivalent to these. In addition, there are various exhaust heat sources such as factory exhaust heat, exhaust heat from motors, hot spring water (geothermal), solar heat, and the like, and also hot water and low-pressure steam generated by these heat sources.

  Conventionally, in such an exhaust heat power generator, the rotational speed of the turbine generator 106 is controlled by a speed governor installed in the turbine generator 106. The speed governor includes a rotational speed detector (not shown), a speed regulating valve, and a control device (not shown), and the rotational speed of the turbine 104 is predicted to exceed (or exceed the rated rotational speed). ), The opening of the governing valve is decreased, and when it is lower, the opening is increased and the rotation speed is kept constant. In addition to this, load control of the high-speed generator 105 is performed. Usually, the load of the high-speed generator 105 is automatically controlled by keeping the rotation speed constant. In order to perform such control, the governing valve is not always fully opened, but must be operated with the minimum opening required for control and closed. For this reason, the following problems arise.

-Since the speed regulating valve is in the working medium piping and causes pressure loss, the power generation efficiency of the power generation apparatus 100 is reduced.
-Due to the above pressure loss, the pressure in the steam generator 101 rises above the steam pressure required for the turbine 104.

As described in Patent Document 1, the inventors of the present application control the output of the system linkage device using the inverse converter so that the DC voltage in the system linkage device becomes a set voltage, thereby controlling the speed control valve. Regardless of this, it is proposed that the turbine generator can keep rotating properly and the generated power can be maximized.
JP 2005-31289 A

  With the technology proposed in Patent Document 1, the power generation device can suppress the turbine of the turbine generator, the rotational speed of the generator, and the like within a specified range without a regulator valve. However, in this technology, if the generated power exceeds the output power (capacity) of the grid linkage device, the power generated by the brake heater will be discarded. Therefore, it is necessary to have a capacity sufficient to generate the generated power corresponding to the turbine output of this type, or to provide a separate regulator to prevent overload, which increases the cost of the product.

  The present invention has been made in view of the above-described points, and does not depend on a speed control valve, while keeping the rotational speed of the turbine generator constant, while minimizing the capacity of the generator, the expander and the generator are overrotated. An object of the present invention is to provide an exhaust heat power generation apparatus that can prevent speed and generator overload, and an operation method of the exhaust heat power generation apparatus.

In order to solve the above-mentioned problems, the present invention comprises a steam generator, introduces an exhaust heat medium from an exhaust heat source into the steam generator, guides the generated working medium vapor to an expander, and uses the expander to generate a generator. The driving medium generates electric power by driving, leads the working medium vapor discharged from the expander to a condenser, cools and condenses the working medium vapor by a low heat medium from a low heat source, and converts the condensed working medium liquid into the steam generator. In the exhaust heat power generator configured to circulate the working medium, the working medium is circulated by a feed pump that circulates the working medium liquid, and the power generated by the generator is passed through an inverse converter. When the power output of the generator or the rotation speed exceeds a predetermined value, the rotation speed of the feed pump is suppressed and the expander and generator are over-rotated / overloaded. Prevents over-rotation and overload Only setting means, when the power to the system for generating power through the inverters of the generator, as the DC voltage of said inverters is a predetermined constant value, increase or decrease the output of the inverters Inverse conversion device output increase / decrease means is provided .

In the exhaust heat power generation device having such a configuration, since the circulation amount of the working medium is equal to the amount of generated steam, the over-rotation / overload prevention means is provided as described above, and the output of the generator or the rotation of the expander When the speed is about to exceed a predetermined value, suppressing the circulation amount of the working medium by suppressing the rotation speed of the liquid supply pump, that is, suppressing the amount of generated working medium vapor. Accordingly, it is possible to prevent the output or rotational speed of the generator from exceeding a predetermined value, that is, over-rotation / overload. In addition, when an inverse conversion device output increasing / decreasing means is provided and the power generated by the generator is transmitted to the system via the inverse conversion device, the reverse conversion device has a predetermined constant value so that the DC voltage in the inverse conversion device becomes a predetermined constant value. Increasing or decreasing the output maximizes the generated power while maintaining the rotation of the expander and the generator appropriately.

Further, in the exhaust heat power generation apparatus according to the present invention, the over-rotation / overload prevention means is configured to reduce the rotation speed of the feed pump when the output power of the generator or the number of rotations falls below a predetermined value . It is characterized by releasing the suppression .

When the output power of the generator or the number of rotations falls below a predetermined value as described above, the suppression of the rotation speed of the feed pump is canceled, so if the overspeed or overload condition disappears, the steam generator It is possible to quickly return the generated amount of the working medium vapor to the original state.

Further, the present invention relates to the exhaust heat power generation apparatus, wherein the overspeed / overload prevention means includes at least one of a power generation current, a power generation voltage, and a power generation of the power generator as an index of the load of the expander and the power generator. It is characterized by using one or more.

  Further, the present invention relates to the exhaust heat power generator described above, in the case where power generated by the generator is transmitted to the system via the reverse converter, the direct current in the reverse converter as an indicator of the load of the generator, It is characterized by using at least one of DC voltage, DC power, or AC output current, AC output voltage, AC output power of the inverse converter.

Further, the present invention comprises a steam generator, by introducing the exhaust heat medium from the exhaust heat source to the steam generator, directing the working medium vapor generated in the expander drives a generator in the expander In addition to generating electricity, the working medium vapor discharged from the expander is led to a condenser to cool and condense the working medium vapor with a low heat medium from a low heat source, and the condensed working medium liquid is supplied to the steam generator. The exhaust heat power generation apparatus is configured to circulate the working medium , wherein the working medium is circulated by a feed pump that circulates the working medium liquid, and the generated power of the generator is inverted. allowing transmission to the system through the output of the generator, or when the rotation speed is about to exceed a predetermined value, the over-rotation and of the expander and the power generator to suppress the rotation speed of the liquid supply pump Preventing overload, the output power of the generator, If properly the rotational speed falls below the predetermined value, the liquid supply to release the rotational speed of the suppression of the pump, when the power to the system for generating power through the inverters of the generator, the inverse transform apparatus The output of the inverse conversion device is increased or decreased so that the direct current voltage becomes a predetermined constant value .

As described above, when the output or rotational speed of the generator is about to exceed a predetermined value, the circulation rate of the working medium is suppressed by suppressing the rotational speed of the feed pump, and the excess of the expander and the generator is exceeded. When rotation / overload is prevented and the output power or rotation speed of the generator falls below the predetermined value, the circulation rate of the working medium is suppressed by releasing the suppression of the rotation speed of the feed pump. When the over-rotation / overload state disappears while avoiding over-rotation / overload of the expander and generator, the working medium vapor generation amount of the steam generator is quickly returned to the original state. Is possible. In addition, when the generated power of the generator is transmitted to the system via the inverter, the output of the inverter is increased or decreased so that the DC voltage in the inverter becomes a predetermined constant value. It will keep the rotation properly and maximize the generated power.

According to the present invention, when the output of the generator or the rotation speed exceeds a predetermined value, the rotation speed of the feed pump is suppressed to suppress the circulation amount of the working medium. Is equal to the amount of working medium vapor generated by the steam generator, so reducing the circulating amount of working medium will reduce the amount of working medium vapor generated, and even if the capacity of the generator is minimized, The overspeed and overload of the expander and the generator can be prevented. In addition, when the generated power of the generator is transmitted to the system via the inverter, the output of the inverter is increased or decreased so that the DC voltage in the inverter becomes a predetermined constant value. The generated power can be maximized while maintaining proper rotation.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a configuration example of the exhaust heat power generator according to the present invention. This exhaust heat power generation apparatus includes the power generation apparatus 10, using hot water of about 80 ° C. sent from the exhaust heat source 30 by a hot water circulation pump as a heat source, and cooling water supplied from the cooling tower 40 by a cooling water pump 41 as a low temperature heat source. It is a waste heat power generator that generates electricity. The power generation apparatus 10 includes a steam generator 11, a droplet separator 12, a main steam valve 13, a turbine 14 as an expander and a turbine generator 16 having a high-speed generator 15, a condenser 17, and a feed pump 18. These are connected by a working medium pipe 19. The power generator 10 is controlled by the control panel 20, and AC power generated by the high-speed generator 15 is converted into DC power by the high-frequency rectifier 21, and further AC power (generally commercial power of 50 Hz or 60 Hz) by the system linkage device 22. And is transmitted to the grid 23.

  By supplying hot water from the exhaust heat source 30 to the steam generator 11 with the hot water circulation pump 31, the working medium liquid supplied from the condenser 17 to the steam generator 11 by the liquid supply pump 18 is heated to become working medium vapor. Then, the liquid is discharged from the vapor outlet of the evaporation generator 11 and supplied to the droplet separator 12 through the working medium pipe 19. The working medium pipe 19 connected to the steam outlet is provided with a pressure sensor 24 for measuring the pressure of the working medium vapor and a temperature sensor 25 for measuring the temperature, and the output is transmitted to the control panel 20. It has become. The working medium vapor from which the droplets are separated and removed by the droplet separator 12 is supplied to the turbine 14 of the turbine generator 16 through the main steam valve 13, and the separated droplets are returned to the steam generator 11.

  The turbine 14 supplied with the working medium vapor rotates and drives the high-speed generator 15. The working medium vapor discharged from the turbine 14 is supplied to the condenser 17, where it is cooled by the cooling water supplied from the cooling tower 40 by the cooling water pump 41 and condensed to become a working medium liquid. The working medium liquid is sent again to the steam generator 11 by the feed pump 18 and the working medium circulates. Here, as the working medium, it is preferable to use a working medium having a low boiling point (boiling point is around 40 ° C.), such as dichlorotrifluoroethane HFC13 or trifluoroethanol CF 3 CH 2 OH.

  The control panel 20 monitors the output of the high speed generator 15 from the output of the rotation speed / output detector 26, and when the output of the high speed generator 15 exceeds a predetermined set value, the rotation speed of the liquid supply pump 18 is reduced. , Suppress the circulating amount of working medium. Further, the rotational speed of the high speed generator 15 is simultaneously monitored from the output of the rotational speed / output detector 26. When the rotational speed of the high speed generator 15 exceeds a predetermined set value, the rotational speed of the liquid supply pump 18 is decreased. , Suppress the circulating amount of working medium. Moreover, when the output and rotational speed of the high-speed generator 15 are less than the predetermined set value, the suppression of the circulation amount of the working medium is released. As an index of the load (output) of the high-speed generator 15, at least one of generated AC current, generated AC voltage, and generated AC power is used.

  When neither the output of the high-speed generator 15 nor the rotational speed exceeds the set value, the control panel 20 determines the steam from the output of the pressure sensor 24 and the temperature sensor 25 from the pressure and temperature of the working medium steam at the steam outlet of the steam generator 11. By calculating the superheat degree of the working medium vapor at the steam outlet of the generator 11 and increasing or decreasing the rotational speed of the liquid feed pump 18 so that the calculated superheat degree becomes a predetermined set value (target value), the working medium is obtained. Increases or decreases the amount of circulation. Specifically, when the degree of superheat exceeds the target value, the rotational speed of the liquid supply pump 18 is temporarily increased, and when it is lower, the rotational speed is decreased temporarily. Thereby, the superheat degree of the working-medium vapor | steam emitted from the steam outlet of the steam generator 11 can be maintained at a target value.

  Here, when the rotational speed of the turbine generator 16 or the output of the high-speed generator 15 is about to exceed the set value, the control panel 20 temporarily sets the rotational speed of the liquid feed pump 18 regardless of the degree of superheating of the working medium vapor. Decrease. As a result, the amount of working medium supplied to the steam generator 11 is temporarily reduced. Since the amount of working medium (liquid) supplied to the steam generator 11 is equal to the amount of working medium vapor generated, reducing the amount of medium supplied for a while suppresses the amount of working medium vapor generated. Become. Therefore, even if the capacity of the high-speed generator 15 is suppressed, it is possible to avoid the turbine 14 and the high-speed generator 15 from becoming overloaded or over-rotating speed. In the above example, the circulation amount of the working medium is increased or decreased by temporarily increasing or decreasing the rotation speed of the feed liquid pump 18, but instead of depending on the rotation speed of the supply liquid pump 18, the working medium is being supplied to the steam generator 11. A control valve and a return valve may be provided to control the opening degree. However, power consumption can be reduced by relying on control of the rotational speed.

  FIG. 3 is a diagram showing a functional configuration of the superheat degree control of the control panel 20. The control panel 20 includes a superheat degree calculation unit 20-1, a PID calculation unit 20-2, a target value (target superheat degree) setting unit 20-3, a pressure fluctuation correction unit 20-4, and a rotation speed control unit 20-5. I have. The steam pressure and steam temperature of the working medium steam measured by the pressure sensor 24 and the temperature sensor 25 provided in the working medium pipe 19 connected to the steam generator outlet of the steam generator 11 are supplied to the superheat degree calculation unit 20-1. The superheat degree calculation unit 20-1 is inputted and calculates the superheat degree of the working medium vapor from the vapor pressure and the vapor temperature. In the PID calculation unit 20-2, the calculated superheat degree is compared with the target superheat degree (about 3 ° C.) set by the target value setting unit 20-3, and when it is low, the feed pump 18 is supplied to the rotation speed control unit 20-5. A command to temporarily increase the rotational speed of the liquid feed pump 18 is output if the calculated superheat degree is higher than the target superheat degree.

  In the above example, the working medium liquid flow rate is increased / decreased by increasing / decreasing the rotational speed of the liquid supply pump 18, but is not limited to increasing / decreasing the rotational speed of the liquid supply pump 18 as long as the working medium liquid flow rate can be increased / decreased. .

  In the exhaust heat power generator, when the control panel 20 transmits the power generated by the turbine generator 16 to the grid 23 via the reverse converter (system linkage apparatus 22), the DC voltage in the reverse converter is By increasing / decreasing the output of the inverse converter so as to be constant, the rotation of the turbine generator 16 can be properly maintained and the generated power can be maximized. FIG. 4 is a diagram illustrating a configuration example of the inverse conversion device. The AC output power of the high speed generator 15 of the turbine generator 16 is converted to DC power by the high frequency rectifier 21 and smoothed by the smoothing capacitor 22-1. The inverter 22-3 converts this DC power into AC power and transmits it to the system 23. The control panel 20 monitors the output-side DC voltage of the high-frequency rectifier 21 based on the output of the voltmeter 22-2, and increases or decreases the AC output from the inverter 22-3 so that the DC voltage is constant, thereby generating turbine power generation. Maintain the rotation of the machine 16 properly and maximize the generated power.

  When the power generated by the high-speed generator 15 is transmitted to the system 23 via the reverse conversion device (system linkage device 22), the load index of the high-speed generator may be a DC current or a DC voltage (voltage) in the system linkage device 22. Output of the total 22-2), or at least one of the AC output current, the AC output voltage, and the AC output power of the system linkage device 22 is used.

  In the above exhaust heat power generation apparatus, an example is shown in which hot water is introduced from the exhaust heat source 30 into the steam generator 11 as a heat source, and the cooling water from the cooling tower 40 is used as the low temperature source for the condenser 17. The source is not limited to this, and the exhaust gas from the exhaust heat source may be used as the heat source, and air (air-cooled condenser), river water, or the like may be used as the low-temperature heat source. Moreover, you may use the secondary fluid by this low temperature heat source and heat exchange, or another technique equivalent to these. In addition, there are various exhaust heat sources such as factory exhaust heat, exhaust heat from motors, hot spring water (geothermal), solar heat, and the like, and hot water or low-pressure steam generated by these heat sources may be used.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, in the above example, the turbine generator 16 that uses the turbine 14 as the expander and drives the high-speed generator 15 with the turbine has been described. However, the working medium vapor is supplied to the expander and is generated by the expansion of the working medium vapor. Any configuration may be used as long as the generator is driven by a mechanical rotational force.

It is a figure which shows the structural example of the conventional waste heat power generator. It is a figure which shows the structural example of the waste heat power generator which concerns on this invention. It is a figure which shows the function structure of the superheat degree control of the control panel of the exhaust heat power generator which concerns on this invention. It is a figure which shows the structural example of the reverse conversion apparatus of the waste heat power generator which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Power generator 11 Steam generator 12 Droplet separator 13 Main steam valve 14 Turbine 15 High speed generator 16 Turbine generator 17 Condenser 18 Feed pump 19 Working medium piping 20 Control panel 21 High frequency rectifier 22 System linkage apparatus 23 System 24 Pressure sensor 25 Temperature sensor 26 Rotation speed / output detector 27 Level gauge 30 Waste heat source 31 Hot water circulation pump
40 Cooling tower 41 Cooling water pump

Claims (5)

A steam generator is provided, an exhaust heat medium from an exhaust heat source is introduced into the steam generator, the generated working medium steam is guided to an expander, and the generator is driven by the expander to generate electric power. The working medium vapor discharged from the condenser is led to a condenser, the working medium vapor is cooled and condensed by the low heat medium from the low heat source, and the condensed working medium liquid is supplied to the steam generator to circulate the working medium. In the exhaust heat power generator configured as described above,
Circulation of the working medium is performed by a feed pump that circulates the working medium liquid, and the generated power of the generator can be transmitted to the system via an inverse conversion device,
When the output or rotational speed of the generator is about to exceed a predetermined value, the rotational speed of the liquid supply pump is suppressed to prevent over- expansion / overload of the expander and the generator. set the load prevention means,
Inverter output for increasing / decreasing the output of the inverter so that the DC voltage in the inverter becomes a predetermined constant value when transmitting the power generated by the generator to the system via the inverter An exhaust heat power generator having an increase / decrease means . The exhaust heat power generator according to claim 1 ,
The over-rotation / over-load prevention means releases the suppression of the rotation speed of the liquid supply pump when the output power or rotation speed of the generator falls below a predetermined value. . The exhaust heat power generator according to claim 1 or 2 ,
The over-rotation / overload prevention means uses at least one of the power generation current, power generation voltage, and power generation of the power generator as an index of the load of the expander and power generator. apparatus. The exhaust heat power generator according to any one of claims 1 to 3 ,
If you transmitting the generated power of the generator to the grid through the inverters, as an indication of the load of the generator, the DC current of said power inverter, DC voltage, DC power, or inverse converter An exhaust heat power generation apparatus using at least one of an AC output current, an AC output voltage, and an AC output power. A steam generator is provided, an exhaust heat medium from an exhaust heat source is introduced into the steam generator, the generated working medium steam is guided to an expander, and the generator is driven by the expander to generate electric power. The working medium vapor discharged from the condenser is led to a condenser, the working medium vapor is cooled and condensed by the low heat medium from the low heat source, and the condensed working medium liquid is supplied to the steam generator to circulate the working medium. An operation method of the exhaust heat power generator configured as described above,
Circulation of the working medium is performed by a feed pump that circulates the working medium liquid, and the generated power of the generator can be transmitted to the system via an inverse conversion device,
When the output or rotation speed of the generator is about to exceed a predetermined value, the rotation speed of the feed pump is suppressed to prevent over-rotation / overload of the expander and the generator, and the generator When the output power of the engine, or the rotation speed is less than the predetermined value, canceling the suppression of the rotation speed of the liquid feed pump, and when transmitting the generated power of the generator to the system via an inverse converter, A method for operating an exhaust heat power generator , wherein the output of the inverse converter is increased or decreased so that the DC voltage in the inverter becomes a predetermined constant value .

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