JP2011214490A - Waste heat utilization system of engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat utilization system of engine with supercharger that enhances stability of operation at operation start.SOLUTION: The waste heat utilization system of engine with supercharger includes a supercharger 1; an inter-cooler 2 arranged on the downstream side of the supercharger 1, wherein heating medium circulates in the inside; an engine 3; and a hot water storage tank 4 for reserving hot water which has been heat-exchanged with the heating medium. The waste heat utilization system further includes a first temperature detection means 90 that detects a temperature of the heating medium, and a second temperature detection means 91 that detects a temperature of the hot water contained in the hot water storage tank 4. In a state where the engine 3 is stopped, when a temperature value T1 detected by the first temperature detection means 90 is equal to or higher than a temperature value T2 detected by the second temperature detection means 91, the heating medium is not circulated, and when the temperature value T1 is less than the temperature value T2 detected by the second temperature detection means 91, the heating medium that has been heat-exchanged with the hot water contained in the hot water storage tank 4 is circulated, so that an operation of the engine 3 is started at this state.

Description

  The present invention relates to a waste heat utilization system for a supercharged engine.

  2. Description of the Related Art Conventionally, there has been known an exhaust heat utilization system that recovers exhaust heat from an intercooler attached to an engine with a supercharger and effectively uses the recovered heat (see, for example, Patent Document 1). As a system using the exhaust heat of this supercharged engine, for example, there is the following. In this example, the exhaust heat utilization system for an engine with a supercharger includes an engine serving as a power source such as a generator, a supercharger that is provided upstream of the engine and sends compressed air to the engine, an engine and a supercharger. And an intercooler that is provided between the turbocharger and cools the compressed air generated by the supercharger. Cooling water (heating medium) circulates in this intercooler, and this cooling water exchanges heat with the compressed air passing through the intercooler. On the other hand, the cooling water heat-exchanged with compressed air can exchange heat with warm water or a heat radiating device such as a cooling tower outside the intercooler. The hot water that exchanges heat with the cooling water of this intercooler is in a high-temperature state together with the hot water that is obtained by exchanging heat with the cooling water of the engine body and the hot water that is obtained by exchanging heat with the exhaust gas. Stored in a hot water storage tank. In this way, exhaust heat from the engine with a supercharger can be recovered, and the recovered heat can be reused for various purposes.

JP 11-182975 A

  By the way, when the engine continues to operate to some extent from the time of starting, the temperature of the main body becomes high, and the engine can be driven stably without misfire. However, since the main body is often cooled before or immediately after the engine is started, the temperature of the compressed air flowing into the engine from the supercharger decreases in the process of flowing in, and the temperature further decreases during ignition and combustion. Become. As a result, combustibility is deteriorated. In this case, there is a problem that not only the startability of the engine is deteriorated but also misfire immediately after the start is easily caused.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust heat utilization system for an engine with a supercharger that improves the stability of operation at the start of operation.

  In order to solve the above problems, the exhaust heat utilization system for a supercharged engine of the present invention has the following configuration.

  The present invention includes a supercharger 1 that compresses sucked air, an intercooler 2 that is disposed downstream of the supercharger 1 and that exchanges heat between the heat medium that circulates inside and the compressed air, An engine 3 disposed downstream of the cooler 2, hot water exchanged with the heat medium, hot water obtained by heat exchange with the cooling water of the engine body, hot water obtained by heat exchange with the exhaust gas, etc. This is a waste heat utilization system of a supercharged engine equipped with a hot water storage tank 4 for storage. This further includes a first temperature detecting means 90 for detecting the temperature of the heat medium, and a second temperature detecting means 91 for detecting the temperature of the hot water in the hot water storage tank 4. When the engine 3 is stopped, when the temperature value T1 detected by the first temperature detection means 90 is equal to or higher than the temperature value T2 detected by the second temperature detection means 91, the heat medium is not circulated, When the temperature is less than the temperature value T2 detected by the temperature detecting means 91, the heat medium exchanged with the hot water in the hot water storage tank 4 is circulated, and the operation of the engine 3 is started in this state. To do.

  According to such a configuration, when the temperature value T1 of the heat medium of the intercooler 2 is lower than the temperature value T2 of the hot water in the hot water storage tank 4 when the engine 3 is started, the high temperature heat medium is circulated in the intercooler 2. be able to. If a high-temperature heat medium circulates in the intercooler 2, even if the engine 3 is cold, the compressed air sent from the supercharger 1 to the engine 3 is not excessively cooled. 3. The combustibility of compressed air at the time of starting can be improved. On the other hand, when the temperature value T1 of the heat medium in the intercooler 2 is equal to or higher than the temperature value T2 of the hot water in the hot water storage tank 4, the heat medium that exchanges heat with the hot water in the hot water storage tank 4 is not circulated in the intercooler 2. In this case, too, the compressed air sent from the supercharger 1 into the engine 3 can be prevented from being cooled excessively.

  According to the exhaust heat utilization system for an engine with a supercharger according to the present invention, the stability of the operation at the start of operation can be improved.

1 is a schematic diagram of one embodiment of the present invention.

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

  An exhaust heat utilization system for an engine with a supercharger (hereinafter referred to as an exhaust heat utilization system) of the present embodiment includes an intercooler 2 for cooling the compressed air supplied from the supercharger 1. Hot water is generated by using the exhaust heat from the cooler 2, and the hot water storage tank is combined with hot water obtained by exchanging heat with the cooling water of the engine body, hot water obtained by exchanging heat with the exhaust gas, etc. 4 is used afterwards. As shown in FIG. 1, the exhaust heat utilization system includes a supercharger 1, an intercooler 2 provided on the downstream side of the air flow path of the supercharger 1, and an air flow path downstream of the intercooler 2. The engine 3 provided and the hot water storage tank 4 which stores the hot water heated by the exhaust heat of the intercooler 2 are provided. The exhaust heat utilization system further includes a cooling tower 5 for generating a cooling liquid for cooling the heat medium circulating in the intercooler 2. This exhaust heat utilization system generates power using the power of the engine 3, and simultaneously performs the power generation by the engine 3 and the recovery and use of heat from the intercooler 2, the cooling water of the engine body, and the exhaust gas. It constitutes a so-called cogeneration system.

  The supercharger 1 uses a turbocharger that rotates the turbine using the exhaust gas of the engine 3 and compresses the intake air. The supercharger 1 has a suction port for taking air into the interior and a discharge port for discharging air compressed by the turbine. This discharge port is connected to a premixing section 6 that premixes compressed air and fuel downstream thereof. The precooling section 6 is further connected to the intercooler 2 on the downstream side.

  The intercooler 2 is connected to the downstream side of the supercharger 1 and exchanges heat with the air supplied from the supercharger 1 by a heat medium that circulates inside. The intercooler 2 of the present embodiment cools the air supplied from the supercharger 1 during normal operation, but is supplied from the supercharger 1 when the engine 3 is started (a certain period of time immediately after starting). It also serves to raise or maintain the temperature of the air. As shown in FIG. 1, the intercooler 2 is provided with a heat medium circulation pipe 80 through which the heat medium pumped by the first pump 70 circulates. The intercooler 2 is disposed so as to exchange heat with the compressed air supplied from the supercharger 1. The heat medium circulation pipe 80 has a cooling tower side pipe 81 and a hot water tank side pipe 82, and the cooling tower side pipe 81 and the hot water tank side pipe 82 are connected via a switching valve 73. Switching is possible. The cooling tower side pipe line 81 is connected to a cooling tower heat exchanger 83 in the middle thereof. The hot water storage tank side pipe line 82 is connected to a hot water storage tank heat exchanger 84 in the middle thereof.

  The hot water storage tank 4 is connected to the hot water storage tank heat exchanger 84, and stores hot water exchanged in the hot water storage tank heat exchanger 84. The hot water storage tank 4 is provided with a hot water circulation path 85 that communicates with the inside of the hot water storage tank 4. A hot water tank heat exchanger 84 and a second pump 71 are connected to the hot water circulation path 85. The hot water storage tank 4 stores hot water of about 88 ° C. at maximum, and the hot water in the hot water storage tank 4 is used for hot water supply, air conditioning, and the like.

  The cooling tower 5 generates a cooling liquid that cools the heat medium when the intercooler 2 is cooled. The cooling tower 5 is provided with a cooling water circulation path 86, and the cooling water circulation path 86 is connected to the cooling tower heat exchanger 83 and the third pump 72. By driving the third pump 72, the cooling liquid generated by the cooling tower 5 exchanges heat with the heat medium flowing through the intercooler 2 in the cooling tower heat exchanger 83.

  The engine 3 takes in a premixed gas obtained by premixing compressed air and fuel, and obtains power by burning the premixed gas. The engine 3 of the present embodiment is connected to the generator A and generates electricity by being driven. The exhaust gas generated during combustion is used for supercharging of the supercharger 1 as described above.

  As shown in FIG. 1, the exhaust heat utilization system of the present embodiment includes temperature detection means in the vicinity of the discharge port of the supercharger 1, the heat medium circulation pipe 80 in the intercooler 2, and the hot water storage tank 4. 90, 91, 92 are provided. The temperature detection means (first temperature detection means 90) provided in the heat medium circulation pipe 80 in the intercooler 2 detects the temperature of the heat medium flowing through the intercooler 2. Further, the temperature detection means (second temperature detection means 91) provided in the hot water storage tank 4 detects the temperature of the hot water stored in the hot water storage tank 4. Further, a temperature detection means (third temperature detection means 92) provided near the discharge port of the supercharger 1 detects the temperature of the air compressed by the supercharger 1. These temperature detection means 90, 91, 92 are constituted by temperature sensors, and each is connected to the control unit.

  The control unit performs an operation for improving the startability of the engine 3 for a certain period of time before the engine 3 is started and when the engine 3 is started. The control unit is connected to each of the pumps 70, 71, 72, and performs ON / OFF control of the first pump 70 and the second pump 71 based on the detection values of the temperature detection means 90, 91, 92. When a signal for starting operation of the exhaust heat utilization system is sent by turning on the system start switch, the control unit sends a command to each temperature detection means 90, 91, 92 to perform temperature detection. Then, each temperature detection means 90, 91, 92 detects each temperature of the heat medium of the intercooler 2, the hot water of the hot water storage tank 4, and the air discharged from the supercharger 1 at the start of operation. Each temperature detection means 90, 91, 92 transmits the temperature value of each part to the control unit. The control unit sends each temperature value sent from the temperature detecting means 90, 91, 92 (temperature value by the first temperature detecting means 90: T1, temperature value by the second temperature detecting means 91: T2, third temperature. The magnitude relationship of the temperature value: T3) by the detection means 92 is determined. When the control unit determines that the second temperature detection unit 91 is the largest of the detected temperature values (T2> T1> T3, T2> T3> T1), the first pump 70 and the second pump The operation of 71 is started. Then, the hot water in the hot water storage tank 4 starts to circulate in the hot water circulation path 85. At the same time, the heat medium in the intercooler 2 starts to circulate in the heat medium circulation pipe 80 and exchanges heat with hot water in the hot water storage tank heat exchanger 84. Then, the temperature in the intercooler 2 rises. When the supercharger 1 and the engine 3 are started in this state, the compressed air supplied from the supercharger 1 is heated and flows into the engine 3 to be finally ignited. At this time, since the temperature of the compressed air has risen, even if the engine 3 is cold, the temperature does not drop too much at the time of ignition, the engine 3 is less prone to misfire, and the operation at the start is stable. .

  Here, when the temperature values detected by the temperature detecting means 90, 91, 92 have a relationship of T3> T2> T1, the temperature of the compressed air greatly decreases when it passes through the intercooler 2 in this state. End up. For this reason, a control part starts the driving | operation of the 1st pump 70 and the 2nd pump 71, performs heat exchange with the hot water in the hot water storage tank 4, and the heat medium of the intercooler 2, and reduces the temperature of compressed air Control to keep to a minimum.

  On the other hand, when the control unit determines that the temperature value T1 detected by the first temperature detecting means 90 is the largest (T1 ≧ T3 ≧ T2, T1> T2> T3), the control unit drives the pumps 70 and 71. Without starting, the engine 3 is started as it is. Then, since the compressed air from the supercharger 1 has a higher temperature in the intercooler 2, it is heated by the intercooler 2, and then flows into the engine 3 and ignites. At this time, since the temperature of the compressed air is rising, the engine 3 is unlikely to cause misfire and the operation at the start is stabilized.

  Here, when the temperature values detected by the temperature detecting means 90, 91, 92 are in a relationship of T3> T1> T2, the temperature of the compressed air decreases when it passes through the intercooler 2 in this state. Even if the pumps 70 and 71 are driven and the heat medium in the intercooler 2 is circulated, the temperature further decreases. For this reason, the control unit does not drive the pumps 70 and 71 and controls the temperature drop of the compressed air to be kept to a minimum.

  That is, when attention is paid to the relationship between the first temperature detecting means 90 and the second temperature detecting means 91, the control of the control unit is as follows. When the temperature value T1 detected by the first temperature detection means 90 is equal to or higher than the temperature value T2 detected by the second temperature detection means 91 (T1 ≧ T2), the control unit is connected to the first pump 70 and the second pump 70. The pump 71 is not operated. On the other hand, when the temperature value T1 detected by the first temperature detection means 90 is less than the temperature value T2 detected by the second temperature detection means 91 (T1 <T2), the control unit is connected to the first pump 70. The second pump 71 is operated. In this state, the engine 3 is controlled to start.

  The control unit performs the above control when the engine 3 is started, and performs control for switching to normal operation after the engine 3 is operated for a certain period of time in this state. Since the control unit is connected to the switching valve 73, the control unit can perform switching control from the hot water tank side pipe line 82 to the cooling tower side pipe line 81. Thereby, after the operation of the engine 3 is stabilized, the compressed air can be cooled by the intercooler 2. The compression ratio of the compressed air can be increased by the action of the normal intercooler 2, and self-ignition before ignition of the compressed air can be prevented.

  In the exhaust heat utilization system of the present embodiment, when the temperature of the heat medium of the intercooler 2 is lower than the temperature of the hot water in the hot water storage tank 4 when the engine 3 is started, a high-temperature heat medium is circulated in the intercooler 2. Can do. If a high-temperature heat medium circulates in the intercooler 2, even if the engine 3 is cold, the compressed air sent from the supercharger 1 to the engine 3 is not excessively cooled. 3. The combustibility of compressed air at the time of starting can be improved. On the other hand, when the temperature of the heat medium in the intercooler 2 is equal to or higher than the temperature of the hot water in the hot water storage tank 4, the heat medium exchanged with the hot water in the low temperature hot water storage tank 4 is not circulated in the intercooler 2. The compressed air sent from 1 to the engine 3 can be prevented from being excessively cooled. As a result, the stability of the operation at the start of operation can be improved.

  In the exhaust heat utilization system of the present embodiment, the third temperature detection unit 92 is provided, and the temperature of the compressed air from the supercharger 1 is detected by the third temperature detection unit 92. In the exhaust heat utilization system for an engine with a supercharger according to the present invention, the third temperature detecting means 92 is not necessarily required.

  In this embodiment, the heat exchange between the heat medium flowing in the intercooler 2 and hot water is directly performed between the heat medium and hot water. However, the present invention relates to the heat medium flowing in the intercooler and the hot water. The heat exchange with the heat medium may be performed via another heat medium between the heat medium and hot water.

  Moreover, although the exhaust heat utilization system of this embodiment comprised the cogeneration system, the exhaust heat utilization system of the engine with a feeder of this invention may not be a cogeneration system, but the engine of a supercharger engine. Any system that uses exhaust heat can be widely applied. In the exhaust heat utilization system of the present embodiment, the supercharger 1 is configured by a turbocharger. However, in the exhaust heat utilization system of the engine with a turbocharger of the present invention, the supercharger may be a supercharger. This is not a limitation.

DESCRIPTION OF SYMBOLS 1 Supercharger 2 Intercooler 3 Engine 4 Hot water storage tank 5 Cooling tower 6 Premixing chamber 70 1st pump 71 2nd pump 72 3rd pump 73 Switching valve 80 Heating medium circulation line 81 Cooling tower side line 82 Hot water storage tank side pipe 83 Heat exchanger for cooling tower 84 Heat exchanger for hot water storage tank 85 Hot water circulation path 86 Cooling water circulation path 90 First temperature detection means 91 Second temperature detection means 92 Third temperature detection means A Power generation Machine

Claims (1)

A supercharger that compresses the inhaled air;
An intercooler that is arranged on the downstream side of the supercharger and exchanges heat between the heat medium flowing inside and the compressed air;
An engine disposed downstream of the intercooler;
A hot water storage tank for storing hot water exchanged with the heat medium;
An exhaust heat utilization system for a turbocharged engine equipped with
First temperature detecting means for detecting the temperature of the heat medium;
A second temperature detecting means for detecting the temperature of the hot water in the hot water storage tank;
In a state where the engine is stopped, the temperature value detected by the first temperature detecting means is
When the temperature value detected by the second temperature detecting means is higher than the temperature value, the heating medium is not circulated, and when the temperature value is less than the temperature value detected by the second detecting means, the heat medium exchanged with hot water in the hot water storage tank is circulated. Let
An exhaust heat utilization system for an engine with a supercharger, characterized in that the operation of the engine is started in this state.

Images