JPS6158658B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust heat recovery device for a heat engine, and particularly to an exhaust heat recovery device suitable for equipment powered by an internal combustion engine such as a diesel engine.

As shown in FIG. 1, a conventional exhaust heat recovery device of this type includes a water supply section 2a of a cooling water heat exchanger 2 for cooling cooling water of a heat engine 1, and a water supply section 2a of a cooling water heat exchanger 2 for cooling cooling water of a heat engine 1; The water supply section 3a of the exhaust gas heat exchanger 3 for recovering exhaust heat is connected in parallel to the water supply system, and the supplied water is transferred to these heat exchangers 2,
There is a known method that heats each part separately. In the figure, 2b is a cooling water section, and 3b is an exhaust gas section. However, this conventional device has the disadvantage that it is difficult to obtain hot water at a high temperature because the supplied water is heated separately in each of the heat exchangers 2 and 3.

In order to obtain high-temperature hot water, as shown in Fig. 2, the water supply section 2a of the cooling water heat exchanger 2 and the water supply section 3a of the exhaust gas heat exchanger 3 are connected in series, and the supplied water is It is conceivable to first heat the water in the cooling water heat exchanger 2, and then further heat the heated hot water in the exhaust gas heat exchanger 3. However, in this way, the two heat exchangers 2 and 3 have different flow rate control conditions.
When the water supply parts 2a and 3a are connected in series,
The following problems arise.

For example, when the amount of exhaust heat increases as the load on the heat engine increases, if you try to control the water supply outlet temperature to a constant level, the cooling water of the heat engine will easily overheat, and as the load on the heat engine decreases, the amount of exhaust heat will increase. When the amount of heat decreases,
If an attempt is made to control the water supply outlet temperature to a constant value, the flow rate of the water supply system decreases, resulting in a decrease in the heat recovery efficiency of the heat exchanger. That is, it is difficult to make exhaust heat recovery function stably and highly efficiently in response to changes in the amount of exhaust heat due to changes in the load of the heat engine. Furthermore, when a heat engine starts, the heat engine itself does not warm up quickly, but the combustion gas in the heat engine immediately rises in temperature.
If you try to use the waste heat, the cooling water for the heat engine will also be cooled, causing a further delay in the time it takes for the heat engine to reach a predetermined temperature, causing the problem that it will not be able to produce adequate torque.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust heat recovery device for a heat engine that can solve the above-mentioned problems and can stably and efficiently obtain high-temperature hot water.

In order to achieve this object, the present invention connects the water supply parts of the cooling water heat exchanger and the exhaust gas heat exchanger in series, and also provides a system for directly supplying water to the water supply part inlet side of the exhaust gas heat exchanger. a first waterway, a first control means for controlling the flow rate of water flowing through the first waterway, and a first control means for controlling the flow rate of water flowing through the first waterway; The second to return
The present invention is characterized in that it is provided with a water channel and a second control means for controlling the return amount of hot water flowing through the second water channel.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 3, the same reference numerals as in FIGS. 1 and 2 indicate the same or equivalent parts. Further, 4 to 6 are constant speed rotary pumps, 7 to 10 are control valves, 11 to 13
is a temperature sensor, 14 is a water tank, 15 is a water level sensor,
16 to 21 are water supply pipes, 22 and 23 are cooling water circulation pipes, 24 and 25 are exhaust gas pipes, 26 is a water supply section, 27
28 is the exhaust heat recovery hot water outlet, 28 is the heat engine cooling water outlet,
29 is a heat engine exhaust gas outlet, and 30 is an exhaust gas outlet.

In the exhaust heat recovery device configured in this way, the cooling water discharged from the cooling water outlet 28 of the heat engine 1 is transferred to the pump 6 installed in association with the heat engine 1.
As a result, the water is sent to the cooling water section 2b of the cooling water heat exchanger 2 through the cooling water circulation pipe 23 having the control valve 9, and after being cooled there, it returns to the heat engine 1 through the cooling water circulation pipe 22. At this time, the flow rate of the circulating cooling water is controlled so that the opening degree of the control valve 9 is adjusted according to the deviation between the cooling water temperature detected by the temperature sensor 13 and the set temperature so that the deviation becomes small, that is, the cooling water temperature It is adjusted by controlling so that the temperature is equal to the set temperature. Further, the exhaust gas discharged from the exhaust gas outlet 29 of the heat engine 1 is transferred to the exhaust gas pipe 24.
The exhaust gas reaches the exhaust gas section 3b of the exhaust gas heat exchanger 3, where its thermal energy is recovered, and then is discharged through the exhaust gas pipe 25 through the exhaust gas outlet 30.

On the other hand, water supplied from the water supply port 26 enters the water supply section 2a of the cooling water heat exchanger 2 through the water supply pipe 16, and is branched by a water supply pipe 18 having a control valve 10 and directly flows into the water tank 14. sent.
The water that has entered the water supply section 2a of the cooling water heat exchanger 2 is
Here, as described above, while the cooling water of the heat engine 1 is cooled, it is also heated to become hot water, which is sent into the water tank 14 by the pump 4 through the water supply pipe 17 having the control valve 7 . At this time, the amount of water flowing through the pump 4 is determined by adjusting the opening degree of the control valve 7 according to the deviation between the hot water temperature detected by the temperature sensor 11 and the set temperature so that the deviation becomes small. The temperature of the hot water coming out of the water supply part 2a of the container 2 is controlled to be equal to the set temperature, and the set temperature of the temperature sensor 11 is adjusted when the water level of the water tank 14 detected by the water level sensor 15 is high. It is adjusted to increase as the price increases.

The water in the water tank 14 is sent by the pump 5 through the water supply pipe 19 to the water supply part 3a of the exhaust gas heat exchanger 3, where it is further heated by the thermal energy of the exhaust gas, and the heated hot water has a control valve 8. The water is discharged from the exhaust heat recovery hot water outlet 27 through the water supply pipe 20 . At this time, the water supply part 3a of the exhaust gas heat exchanger 3
The temperature of the hot water flowing out from the hot water outlet 27 is detected by the temperature sensor 12, and the opening degree of the control valve 8 is determined based on the deviation between the detected temperature and the set temperature. It is controlled so that it grows. Note that the hot water that does not flow out from the hot water outlet 27 is returned to the water tank 14 through the water supply pipe 21.

Further, when the temperature detected by the temperature sensor 12 is higher than the set value, or when the water level of the aquarium 1 detected by the water level sensor 15 is lower than the set value,
The opening degree of the control valve 10 is controlled to increase according to the amount of deviation between these and the set value, and the water supply pipe 1
The amount of water supplied directly into the water tank 14 through the water tank 14 increases.

According to this embodiment, since the water supply parts 2a and 3a of the two heat exchangers 2 and 3 are basically connected in series, high-temperature hot water can be obtained, and the cooling water heat exchanger The water supply system 2 is provided with a bypass passage 18 that can control the flow rate, and the water supply system of the exhaust gas heat exchanger 3 is provided with a return passage 21 that can control the flow rate. By controlling each water supply system separately, waste heat can be recovered stably and with high efficiency against disturbances such as changes in the amount of waste heat due to changes in the load of the heat engine 1 and changes in the feed water temperature due to changes in ambient temperature. At the same time, the above-mentioned problem at startup can be solved. Furthermore, since it becomes possible to use constant speed rotation pumps as each of the pumps 4 to 6, it is possible to reduce costs and improve reliability.

In the above embodiment, a control valve is used to adjust the flow rate, but if a variable speed pump having a flow control function is used as the pump, the control valve can be omitted.

As explained above, according to the present invention, high temperature hot water can be obtained stably and with high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing an example of a conventional exhaust heat recovery device for a heat engine, and FIG. 2 is a schematic system diagram showing an example of a heat engine exhaust heat recovery device in which the water supply systems of each heat exchanger are connected in series. FIG. 3 is a system diagram showing an exhaust heat recovery device for a heat engine according to an embodiment of the present invention. 1...Heat engine, 2...Cooling water heat exchanger, 2a
...Water supply section, 3...Exhaust gas heat exchanger, 3a...
Water supply section, 7, 8, 10... Control valve, 11, 12...
... Temperature sensor, 14 ... Water tank, 15 ... Water level sensor, 18 ... Bypass water supply pipe (first waterway),
21...Return water supply pipe (second waterway).

Claims (1)

[Scope of Claims] 1. A heat engine, a cooling water heat exchanger for cooling cooling water of the heat engine, and an exhaust gas heat exchanger for recovering exhaust heat of combustion gas of the heat engine. The water supply section of the cooling water heat exchanger and the water supply section of the exhaust gas heat exchanger are connected in series, and the water supplied from the water supply section inlet side of the cooling water heat exchanger is used for cooling water. In the heat exchanger which heats the water, the heated hot water is further heated by the exhaust gas heat exchanger, and the first water is supplied directly to the water supply section inlet side of the exhaust gas heat exchanger. a waterway; a first control means for controlling the flow rate of water flowing through the first waterway; and a first control means for controlling the flow rate of water flowing through the first waterway; 1. An exhaust heat recovery device for a heat engine, comprising: a second return waterway; and a second control means for controlling the return amount of hot water flowing through the second waterway. 2. In claim 1, the first control means controls the flow rate of water flowing through the first waterway in accordance with the hot water temperature at the outlet side of the water supply section of the exhaust gas heat exchanger. An exhaust heat recovery device for a heat engine, characterized in that: 3. In claim 1, the second control means controls the return amount of hot water flowing through the second waterway in accordance with the hot water temperature at the outlet of the water supply section of the exhaust gas heat exchanger. An exhaust heat recovery device for a heat engine, characterized in that: 4. In claim 1, the flow rate of hot water flowing from the water supply section outlet side of the cooling water heat exchanger to the water supply section inlet side of the exhaust gas heat exchanger is determined as the flow rate of the hot water flowing into the water supply section of the cooling water heat exchanger. An exhaust heat recovery device for a heat engine, characterized in that it is provided with a control means for controlling according to the hot water temperature on the outlet side. 5. In claim 1, a water tank is provided between the water supply section outlet side of the cooling water heat exchanger and the water supply section inlet side of the exhaust gas heat exchanger, and the first
and an outlet side of a second water channel are respectively connected to the water tank. 6. In claim 5, the first control means controls the flow rate of water flowing through the first waterway based on the hot water temperature at the outlet side of the water supply section of the exhaust gas heat exchanger and the water level in the water tank. 1. An exhaust heat recovery device for a heat engine, characterized in that it is controlled according to. 7 In claim 5, the flow rate of hot water flowing into the water tank from the water supply section outlet side of the cooling water heat exchanger is defined as the hot water temperature at the water supply section exit side of the cooling water heat exchanger. An exhaust heat recovery device for a heat engine, characterized in that it is provided with a control means for controlling according to the water level of the water tank.