JPH0729240Y2 - Diesel engine for cogeneration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cogeneration system for a diesel engine.

[Conventional technology]

FIG. 3 shows a conventional cogeneration diesel engine. The diesel engine 11 receives the fuel 15 supplied from the fuel tank 14 and drives the generator 12 to generate output electricity 13.

At the same time, the diesel engine 11 drives the cooling water pump 21 to supply the cooling water to the diesel engine 11 to cool each part of the engine to ensure normal operation. The high-temperature cooling water 22 that has become a high temperature by cooling the engine is heat-exchanged with the cold water 41 from the outside by the heat exchanger 23, becomes low-temperature cooling water 34, and is supplied to the cooling-water pump 21, and the above cycle is repeated. . Further, the diesel engine 11 sucks the outside air through the intake pipe 31, and the hot exhaust gas from the engine is discharged through the exhaust pipe 32. Here, the heat exchanger 23
The high-temperature water 42, which has become high in temperature, is further heated by the exhaust of the exhaust pipe 32 by the heater 43, and then stored in the heat storage tank 44, and becomes high-temperature hot water or steam 45 for various purposes.

The heater 43 has an auxiliary burner 51 to which the fuel 16 is supplied from the fuel tank 14.

Next, the operation of the conventional example will be described.

Since the engine output is large when the output power 13 is maximum, the inside of the heat storage tank 44 is maintained at a predetermined temperature or higher even when the demand for high-temperature hot water is large.

However, when the demand for output power is low and the demand for high-temperature hot water 45 is high, the output of the diesel engine 11 is low, and the temperature of the cooling water flowing out from the engine decreases,
Since the temperature of the exhaust gas supplied to the heater 43 also drops, a heat storage tank
The temperature of the high-temperature hot water 45 in 44 drops, causing a problem. Therefore, in such a case, in the conventional example, the auxiliary burner 51 is ignited, the temperature in the heater 43 is increased, and high temperature hot water of a predetermined temperature is heated.
Trying to get 45.

[Problems to be solved by the invention]

As described above, in the conventional system, if the ignition of the auxiliary burner 51 at low load fails, there is a risk of the heater 43 exploding, and a fire may occur in the fuel pipe from the fuel tank 14 to the auxiliary burner 51. There is a risk. Moreover, in order to reduce these risks, various safety devices are required, leading to an increase in system price. Furthermore, recently, the legal regulations for the emission of harmful substances in exhaust gas, especially nitrogen oxides (NOx), are becoming stricter, and the countermeasures are required.

The purpose of the present invention is to eliminate the above-mentioned problems and to greatly reduce the possibility and danger of explosion by eliminating the need for an auxiliary burner, and to reduce the NOx in the exhaust gas by the EGR effect. In providing diesel engine.

[Means for solving problems]

The cogeneration diesel engine that drives the generator of the present invention is one in which cold water is heat-exchanged with exhaust gas for EGR and then heat-exchanged with engine cooling hot water, as shown in FIG.
Alternatively, as shown in FIG. 2, in a system in which the order of heat exchange is changed from that in FIG. A temperature sensor is installed in the heat storage tank that stores hot water or steam, and its output signal is sent to the EGR via the controller.
The feature is that the amount of EGR exhaust gas sent to a valve and recirculated to the engine by opening / closing the valve is controlled.

[Action]

When the temperature of the high-temperature hot water in the heat storage tank decreases because the output power is small and the amount of high-temperature hot water used is large, the intake air temperature rises and the combustion period increases when the EGR valve opening is increased to increase the EGR gas amount. The exhaust temperature can be increased by extending the temperature.
As a result, high temperature hot water having a predetermined temperature can be obtained without an auxiliary burner.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of the first embodiment. 11 is a diesel engine, 12 is a generator, 14 is a fuel tank, 63 is a heat storage tank, 64
Is hot water, 71 is a temperature sensor, 73 is a controller, 101 is an EGR valve, 2
3,62,102 are heat exchangers. Fuel 15 is supplied from the fuel tank 14 to the diesel engine 11, outside air is taken in through the intake pipe 31, exhaust gas is discharged through the exhaust pipe 32a, and the high temperature cooling water pipe 22 is cooled by the engine cooling water heat exchanger 23. After that, low-temperature cooling water is supplied to the water pump 21, and is further supplied to the engine 11 via the water pump to be circulated.

The exhaust pipe 32a is branched, and one of them is connected to the EGR gas heat exchanger 102 from the exhaust pipe 32b through the EGR valve 101, and the EGR pipe 32e is connected to the intake pipe 31. On the other hand, the exhaust pipe 32c is connected to the heater 62 which does not have an auxiliary burner, and is open to the atmosphere through the exhaust pipe 32d. A temperature sensor 71 is attached to the heat storage tank 63, and an output signal 72 from the temperature sensor 71 is input to a controller 73. Controller 73
Outputs a control signal 74 for controlling the opening of the EGR valve 101.

Next, the operation of the above embodiment will be described.

When the output power 13 is the maximum and the usage amount of the high-temperature hot water 64 is the maximum, the EGR valve 101 is opened to some extent by the control signal 74 and a part of the exhaust gas is cooled by the EGR gas heat exchanger 102, and then the intake air Can be mixed with and recirculated in the diesel engine to reduce harmful NOx in the exhaust. EGR gas heat exchanger 10
The cold water 41 injected into the 2 rises slightly in temperature and the hot water 42a
Further, heat is exchanged with the high temperature cooling water 22 from the engine 11 in the engine cooling water heat exchanger 23 to become hot water 42b. This warm water 4
2b is further heated in the heater 62 by the exhaust gas of the exhaust pipe 32c, and then stored in the heat storage tank 63, where hot water or steam 64
And used for various purposes. Note that the high-temperature cooling water 22 from the engine is low-temperature cooling water after being cooled by the heat exchanger 23.
24, and is supplied to the engine 11 via the cooling water pump 21,
Normal operation of the engine 11 is ensured.

Next, when the demand for the output power 13 is small and the demand for high-temperature hot water is large, the hot water temperature in the heat storage tank 63 decreases. The output signal 74 of the temperature sensor 71 causes the EGR valve 101 to be largely opened to reduce the temperature. Therefore, the amount of recirculated EGR gas increases, the exhaust temperature of the engine rises, and the exhaust pipe 32c is guided to the heater 62.
Exhaust temperature becomes high. That is, in the diesel engine, the supply air corresponding to the piston stroke is used for combustion. Increasing the EGR amount reduces the amount of fresh air in the supply air, and the excess air ratio decreases. The reduction of the excess air ratio leads to the extension of the combustion period, reduces the amount of expansion of the gas by the piston until the beginning of exhaust, and the gas is exhausted without the gas temperature decreasing sufficiently, and the exhaust temperature rises. Accordingly, even when the demand for the output power 13 is small and the demand for the high-temperature hot water 64 is large, the temperature of the high-temperature hot water 64 is maintained at a predetermined value.

FIG. 2 shows a second embodiment of the present invention. Exhaust pipe 32a, 32b, 32
The arrangement of c, 32d, EGR pipe 32e, EGR valve 101, and EGR gas heat exchanger 102 is the same as that of the first embodiment, but the injection system passage of the cold water 41 is different from that of the first embodiment. In this second embodiment, the cold water becomes hot water 42a after the temperature of the engine cooling water heat exchanger 23 has been somewhat raised by the high temperature cooling water 22 from the engine 11, and the heat exchanger 102 further heats the EGR exhaust gas and heat. After replacement, the hot water 42b is sent to the heater 62 and the heat storage tank 63. Heat storage tank 63
The operation function of maintaining the hot water temperature inside is the same as that of the first embodiment.

In addition, the high-temperature cooling water 22 of the engine, which was previously cooled by the heat exchange 23,
After heat exchange, the low-temperature cooling water 24 is supplied to the engine via the cooling water pump 21 and contributes to the normal operation of the engine.

[Effect of device]

As described above, according to the present invention, since the output power is small and the amount of high-temperature hot water used is large, when the temperature of the high-temperature hot water in the heat storage tank decreases, the EGR valve opening is increased to reduce the EGR gas amount. When it is increased, the exhaust gas temperature is increased by increasing the intake air temperature and extending the combustion period. This makes it possible to obtain high-temperature hot water of a predetermined temperature without an auxiliary burner, therefore
By adopting the cogeneration system of the present invention, the auxiliary burner provided in the heater can be omitted, and the risk of explosion or the like can be greatly reduced.

In addition, the present invention is a harmful emission in the exhaust due to the EGR effect.
Ox can be reduced and the effect of pollution prevention is great.

[Brief description of drawings]

1 and 2 relate to the present invention. FIG. 1 is an overall block diagram of the first embodiment, FIG. 2 is a corresponding diagram of FIG. 1 of the second embodiment, and FIG. FIG. 11 …… Diesel engine, 12 …… Generator, 22 …… Cooling hot water, 32c …… Exhaust gas, 32e …… EGR pipe, 41 …… Cold water, 23
…… Engine cooling water heat exchanger, 62 …… Heating device, 102 …… E
GR gas heat exchanger, 63 …… heat storage tank, 64 …… hot water or steam, 71 …… temperature sensor, 73 …… controller, 101 …… EGR valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 59-226257 (JP, A) JP 54-156919 (JP, A) JP 61-15427 (JP, Y2)

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A cogeneration system equipped with a system for driving a driven machine such as a generator with a diesel engine and recovering waste heat of the diesel engine, which is branched from an exhaust pipe line and connected to an intake pipe line. EGR gas heat exchanger provided in an EGR pipe having a valve for exchanging heat between EGR exhaust gas and cold water introduced from the outside, and engine cooling water heat for exchanging heat between the cold water and high temperature cooling water after engine cooling First heating means having an exchanger, and second heating means for further heating the heated cold water sent from the EGR gas heat exchanger or the engine cooling water heat exchanger with exhaust gas,
A heat storage tank for storing hot water or steam heated by the second heating means, a temperature sensor for detecting the temperature in the heat storage tank, and the EGR valve based on a temperature detection signal from the temperature sensor. A diesel engine for cogeneration, which has a controller for adjusting the opening of the diesel engine.