JP2016044663A - Engine power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine power generation system which supplies exhaust heat generated in an engine generator to power generation, and which improves power generation efficiency with a simple configuration.SOLUTION: An engine power generation system includes: a generator; an engine connected to a driving shaft of the generator and for driving the generator via the driving shaft; a steam generator connected to an exhaust pipe of the engine, and for generating steam by heating circulation water by the heat from the exhaust pipe; an expander connected to the steam generator via steam piping, and for driving by the steam delivered from the steam generator; and a reduction gear for connecting the expander and the driving shaft of the engine, and for decelerating and transmitting rotational power generated in the expander to the driving shaft of the engine.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine power generation system that generates power with an engine.

  For example, Patent Document 1 discloses a technique that uses exhaust heat of an internal combustion engine: “Evaporator 3 that heats water with waste heat of internal combustion engine 1 connected to transmission 143 to generate high-pressure steam; The high-pressure steam generated in step 1 is converted into a constant torque output, the condenser 5 that liquefies the low-pressure steam discharged from the expander 4, and the water liquefied by the condenser 5 to the evaporator 3. A waste heat recovery device 2 constituting a Rankine cycle is provided by a feed water pump 6 to be supplied, and the expander 4 is connected to a generator / motor 124 via a planetary gear mechanism 122, and the expander 4 is connected to the planetary gear mechanism 122. And is connected to the output shaft 142 of the internal combustion engine 1 through a belt-type continuously variable transmission 123. "

JP 2001-227616 A

  A cogeneration system is known as a system that generates electricity with a generator and supplies the electricity using the generated heat. However, at customer sites where the demand for heat is low, power generation efficiency is important, so there is a problem that exhaust heat is also required for power generation.

  Here, in the exhaust heat recovery method as described in Patent Document 1, in order to use the exhaust heat of the internal combustion engine mounted on the automobile, the generator for recovering the energy obtained by the expander is also the original engine. There is a problem that it must be provided separately from the system, the cost is high, and a new space is required.

  In view of the above problems, an object of the present invention is to provide an engine power generation system that uses exhaust heat generated in an engine generator for power generation and improves power generation efficiency with a simple configuration.

  In order to solve the above problems, one of the representative aspects of the present invention includes a generator, an engine connected to the drive shaft of the generator, and driving the generator via the drive shaft, A steam generator connected to an exhaust pipe and heating the circulating water by heat from the exhaust pipe to generate steam; and the steam sent from the steam generator connected to the steam generator via a steam pipe An expander driven by the motor, and a speed reducer that connects the expander and the drive shaft of the engine, and that decelerates the rotational power generated by the expander and transmits it to the drive shaft of the engine. It is characterized by providing.

  According to the present invention, it is possible to provide an engine power generation system that uses exhaust heat generated in an engine generator for power generation and improves power generation efficiency with a simple configuration.

1 is an overall configuration diagram of an engine power generation system that recovers power from thermal energy of exhaust gas. The whole block diagram of the engine power generation system which collects motive power from the thermal energy of the exhaust gas provided with the water supply container. The control system figure of the engine electric power generation system which recovers motive power from the waste gas which controls the steam flow rate for making recovery power of an expander highly efficient. 1 is an overall configuration diagram of an engine power generation system capable of recovering power from exhaust gas thermal energy and recovering heat as warm water from exhaust gas whose temperature has decreased.

Hereinafter, an engine power generation system that recovers power from exhaust gas according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows an embodiment of an engine power generation system for recovering power from exhaust gas from an engine of an engine generator. The engine generator 1 has a structure in which a generator 3 and an engine 2 are integrated, and the generator and the engine are directly connected to the drive shaft, and the generator is driven at the same rotational speed as the engine. An expander 4 is joined to the engine drive shaft 7 that is protruded from the end portion of the engine via an electromagnetic clutch 6 and a speed reducer 5 at its rotation shaft.

  Next, an apparatus related to generation of steam for driving the expander 4, a steam pipe, and a piping system for circulating water will be described. The exhaust pipe 15 of the engine 2 is connected to the steam generator 8, and high-temperature engine exhaust gas flows into the steam generator 8, and the circulating water flowing in from the circulating water inlet pipe 16 connected to the steam generator 8 is also used. Heat to generate high temperature and high pressure steam.

  The engine exhaust gas heats the circulating water and is then discharged from the exhaust gas outlet pipe 35, and the generated steam flows into the expander via the motor-operated valve (1) 9. In FIG. 1, a screw type expander is shown as a positive displacement expander. Steam flows from the steam inlet pipe 17 into the suction port of the expander 4. In the working chamber formed by the pair of male and female rotors of the expander 4, high-temperature and high-pressure steam expands to rotate the male and female rotors in opposite directions to generate power.

  The steam whose pressure and temperature have decreased due to expansion flows into the condenser 10 from the discharge port through the expander steam outlet pipe 18 and is cooled. The steam cooled by the condenser 10 is condensed and circulated as water. Circulating water exiting the condenser 10 is sent to the cooling jacket 14 of the engine 2 through the engine cooling jacket inlet pipe 19 by the circulation pump 11. The circulating water heated to near the boiling point by cooling the engine with the engine cooling jacket 14 exits from the engine cooling jacket outlet pipe 20 and is pressurized by the feed water pump 12, and passes through the circulating water inlet pipe 16 to the steam generator 8. Sent.

  Here, a check valve 13 is provided between the circulating water inlet pipe 16 connecting the feed water pump 12 and the steam generator 8 in order to prevent backflow from the steam generator 8 to the feed water pump 12. .

  In addition, the condenser 10 cools down sufficiently because the role of the radiator that cools the cooling water that has become high temperature by cooling the engine and the role of the condenser that liquefies the low-pressure steam discharged from the expander are shared sufficiently. Adopt a condenser with heat.

  Moreover, although the screw type is shown as an expander in FIG. 1, you may use other positive displacement expanders, such as a scroll type and a rotary type, according to the amount of steam to generate | occur | produce. When the condenser 10 is cooled by air, the cooling fan 27 radiates heat to the surrounding air. However, water cooling using external cooling water is also possible. The recovered power of the expander 4 is connected to the engine drive shaft 7. Therefore, the expander that is several times faster than the engine speed is connected to the engine drive shaft via the speed reducer 5. Here, when the rotational speeds of the engine and the generator are constant under rated conditions, the temperature and flow rate of the exhaust gas are substantially constant, and the amount of steam generated from the exhaust gas is also substantially constant. Therefore, the specification rotation speed of the expander is set to an efficient rotation speed according to the rated rotation speed of the engine, and the speed ratio of the reduction gear is set to a speed ratio corresponding to the ratio.

  Moreover, it connects via the electromagnetic clutch 6 for cut | disconnecting a connection to an engine drive shaft with respect to generation | occurrence | production of the trouble of an expander, etc. Furthermore, an electric valve (1) 9 is provided that enables control of the amount of steam flowing in to finely adjust the rotation of the expander.

  As described above, in this embodiment, the engine generator generates steam from the exhaust gas of the engine, operates the expander with the generated steam, and recovers power to the drive shaft of the engine generator to generate power generation efficiency. Power recovery from exhaust gas with improved In this way, the generator provided in the engine power generator is used for power recovery by recovering to the engine drive shaft that drives the generator provided in the engine power generation system without providing a dedicated machine for power recovery of the expander. Because the power generation capacity is larger than that of the generator of this type, the power generation efficiency is also high, and it is not necessary to install a separate power generator, so the price can be reduced and the space can be saved. Can do.

  In addition, by sharing the radiator that cools the cooling water that has become a high temperature by cooling the engine and the condenser that liquefies the low-pressure steam discharged from the expander by using a condenser with sufficient cooling heat, It is not necessary to separately provide a radiator for releasing the heat of the cooling water to the outside air and a dedicated condenser for liquefying the low-pressure steam discharged from the expander, and cost and installation space can be reduced.

  In the present embodiment, the water liquefied by the condenser is cooled to the boiling point by cooling the engine through the cooling jacket of the engine, and then sent to the evaporator. This makes it possible to obtain the sensible heat energy required for heating to reach the boiling point in the evaporator from the engine cooling jacket as compared to directly heating the low-temperature water liquefied in the condenser. Much of the energy can be used as energy for evaporation of the circulating water, and a lot of steam can be generated.

Further, the expander of the present embodiment is joined to the engine drive shaft via the electromagnetic clutch 6 and the speed reducer 5 with its rotation shaft. Therefore, transmission loss due to mechanical loss due to rotation can be reduced as compared with, for example, connection with a belt-type continuously variable transmission or the like.

FIG. 2 shows a second embodiment. 2 has the same basic configuration as the embodiment shown in FIG. 1 except that an engine cooling jacket outlet pipe 20 for extracting circulating water from the cooling jacket 14 of the engine 2 and a feed water pump 12 for supplying the circulating water to the steam generator 8. A water supply container 21 for stabilizing the flow is provided by removing bubbles contained in the circulating water. When the circulating water returned from the engine cooling jacket 14 flows in from the upper part of the water supply container 21 and is supplied from the lower water supply container outlet pipe 22, if bubbles are mixed in the circulating water, the water supply container 21. Since the air bubbles are accumulated in the upper space, the air bubbles can be released by opening and closing the air release electromagnetic valve 23. When the circulating water decreases, replenishment is possible by opening and closing the motor-operated valve (2) 25 provided in the pipe from the external water supply pipe 24 provided in the lower part of the water supply tank 21.

  FIG. 3 shows a third embodiment. FIG. 3 mainly shows a signal system for performing output control of the expander 4 in the apparatus configuration shown in the third embodiment. The rotation speeds of the engine 2 and the generator 3 are detected by a rotation detector 29 provided on the shaft of the engine or generator, and the signal is sent to the controller 28. The amount of steam flowing into the suction port of the expander 4 is detected by the pressure sensor 31 and the signal is sent to the controller 28 through a signal line. Similarly, the temperature of the steam is detected by the temperature sensor 30, and similarly, the signal is sent to the controller via a signal line. The motor-operated valve (1) 9 provided in the expander steam inlet pipe 17 can be opened and closed by a signal from the controller 28.

  When the engine and generator speeds are constant under rated conditions, the exhaust gas temperature and flow rate are substantially constant. Therefore, the amount of steam generated from the exhaust gas is also substantially constant.

  In that case, the specified rotational speed of the expander is set to an efficient rotational speed in accordance with the rated rotational speed of the engine, and the speed ratio of the reduction gear is set in accordance with the ratio.

  Here, in the expander, if the volume of the rotor is constant, work is performed by expansion indicated by the ratio of the suction pressure and the discharge pressure. Therefore, in order to match the rotation of the expander with the rotation of the engine, the steam generator As long as the pressure of the steam supplied from the expansion port is constant at the suction port of the expander, it is only necessary.

However, when the engine load and the rotational speed change according to the power generation capacity, when adjusting the rotation of the expander to match the rotation of the engine, the flow rate of the steam flowing into the expander 4 is controlled by the electric valve ( 1) It is possible by opening and closing 9 to control.
That is, when the rotation detector 29 detects a change in the rotational speed of the engine 2 or the generator 3, the pressure P of the steam flowing into the intake port of the expander is detected by the pressure sensor 31 and preset by the controller 28. If the vapor pressure P is higher than the set pressure P0 as compared with the vapor pressure P0, the motor-operated valve (1) 9 is throttled, and when the set pressure P0 is reached, the motor-operated valve (1) 9 is stopped. Conversely, when the vapor pressure P is lower than the set pressure P0, the motor-operated valve (1) 9 is opened, and when the set pressure P0 is reached, the motor-operated valve (1) 9 is stopped. The set pressure P0 is set according to the rotational speed of the engine 2 and the generator 3.

  Similarly to the dry screw compressor, the expander 4 is driven in a non-contact manner by a timing gear with a gap provided between the rotors. The gap is set as small as possible at the specified rotor temperature in terms of performance. Therefore, if the rotor becomes hot and expands above the specified temperature, the rotor may burn out.

In order to prevent this, the inflow steam temperature is detected by the temperature sensor 30, and when the steam temperature exceeds a set value, the motor-operated valve (1) 9 is controlled to close. Accordingly, when an abnormality occurs in the steam generator, the temperature of the expander can be prevented from rising and the rotor can be prevented from seizing.

  FIG. 4 shows still another embodiment 4. The basic configuration is the same as in FIG. 2 and FIG. 3, but the exhaust gas of the engine 2 that has passed through the steam generator 8 is still high in temperature, so a heat exchanger 32 is further provided to heat external water to warm water. Perform heat recovery. Since the water flowing in from the cooling water inlet pipe 33 is heated by the heat exchanger 32 to become hot water, it goes out of the cooling water outlet pipe 34 and then is connected to a water heater to be used as hot water, or the hot water is absorbed by cold water Cooling air conditioning by exhaust heat is possible by connecting to the machine.

  The heat balance in the engine power generation system which collects motive power from the exhaust gas by this invention based on Example 1 of FIG. 1 is shown. Assuming that the exhaust gas temperature of an engine that drives a generator with a power generation capacity of 35 kW is 530 ° C., it is possible to generate 39 kg / h of steam at a temperature of 160 ° C. and a pressure of 0.6 MPa from the circulating water with the steam generator. Thereafter, when the expander is expanded to near atmospheric pressure, the electric power generated from the recovered power in consideration of the efficiency of the expander and the efficiency of the generator is about 1.7 kW. Therefore, the amount of power generation can be increased by about 5% by exhaust heat recovery for a power generation capacity of 35 kW. The steam expanded by the expander is cooled by the condenser and becomes water having a temperature of 20 ° C. and a pressure of 0.08 MPa. Then, it is supplied to a cooling jacket of the engine with a circulation pump, and becomes 90 ° C. and 0.2 MPa hot water by cooling the engine. The circulating water is further pressurized to the pressure at the inlet of the steam generator by a feed water pump and supplied to the steam generator. The exhaust gas exiting the steam generator is discharged to a temperature of 175 ° C. by heating the circulating water.

In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1: engine generator, 2: engine, 3: generator, 4: expander, 5: speed reducer, 6: electromagnetic clutch, 7: engine drive shaft, 8: steam generator, 9: electric valve (1), 10: condenser, 11: circulation pump, 12: feed water pump, 13: check valve, 14: engine cooling jacket, 15: exhaust pipe, 16: circulation water inlet pipe, 17: expander steam inlet pipe, 18: expansion Steam outlet pipe, 19: Engine cooling jacket inlet pipe, 20: Engine cooling jacket outlet pipe, 21: Water supply container, 22: Water supply container outlet pipe, 23: Air discharge solenoid valve, 24: External water supply pipe, 25: Motorized valve (2), 26: electrical output, 27: cooling fan, 28: controller, 29: rotation detector, 30: temperature sensor, 31: pressure sensor, 32: heat exchanger, 33: cooling water inlet piping, 34: cooling Water outlet piping, 35: exhaust gas Mouth tube, 36: Hokiben, 37: absorption chiller

Claims (7)

A generator,
An engine connected to a drive shaft of the generator, and driving the generator via the drive shaft;
A steam generator that is connected to an exhaust pipe of the engine and generates steam by heating circulating water by heat from the exhaust pipe;
An expander connected to the steam generator via a steam pipe and driven by steam sent from the steam generator;
A speed reducer that connects the expander and the drive shaft of the engine, and that decelerates the rotational power generated by the expander and transmits it to the drive shaft of the engine;
An engine power generation system comprising: The claim 1, further comprising:
A condenser connected to the expander via a steam outlet pipe, and condensing steam sent from the expander to generate circulating water;
A cooling jacket that is connected to the condenser via a water pipe and cools the engine by circulating water generated by the condenser;
Circulating water that has flowed out of the cooling jacket is pressurized by a feed water pump and sent to the steam generator. In claim 1 or claim 2, further,
An engine power generation system comprising an electromagnetic clutch capable of disconnecting the connection between the expander and the engine between the speed reducer and the drive shaft of the engine. In any one of Claim 1 thru | or 3, Furthermore,
An engine power generation system comprising a water supply container for removing bubbles contained in circulating water between the cooling jacket and a water supply pump for supplying water to the steam generator. In any one of Claim 1 thru | or 4, Furthermore,
A rotational speed detection sensor for detecting the rotational speed of the generator or the engine;
A motorized valve provided in a steam inlet pipe of the expander;
A pressure sensor for detecting a pressure of steam sucked into the expander;
A controller that controls opening and closing of the motor-operated valve so that the pressure of the steam detected by the pressure sensor becomes a predetermined value when a change occurs in the rotational speed of the generator or the engine detected by the rotational speed detection sensor;
An engine power generation system comprising: In claim 5, further:
A temperature sensor for detecting the temperature of steam sucked into the expander;
The controller is configured to close the motor-operated valve when the temperature detected by the temperature sensor exceeds a predetermined value. In any one of Claims 1 thru | or 6, Furthermore,
An engine power generation system comprising a heat exchanger for exchanging heat between exhaust gas discharged from the steam generator and cooling water.