JPH03237256A - Highly efficient exhaust heat recovery system for cogeneration system - Google Patents

Abstract

PURPOSE:To improve exhaust heat recovery efficiency in a device for feeding cooling water for a driving-motor to a hot water refrigerator so as to apply for a cold demand with cold water obtained from a hot water refrigerator as a medium by feeding the cooling water to the hot water refrigerator after raising its temperature by the air cooler of the driving-motor. CONSTITUTION:At the time of feeding cooling water for a driving-motor (engine) 2 to the heat exchanger 28 of a hot water refrigerator 27 through an air cooler 19 and a conduit, cooling water is fed to the air cooler 19 through a conduit 30a branched from the intermediate part of a conduit 11 for circulating cooling water between the motor 2 and a cooling water cooler 13. Hereupon, the temperature of cooling water is raised with the high temperature air of the air cooler 19. The cooling water from the air cooler 19 is thus fed in the high temperature state to the heat exchanger 28 through a conduit 30b, and this results in improving the coefficient-of-performance of the hot water refrigerator 27. On the other hand, exhaust gas from the engine 2 is fed to a exhaust heat recovery boiler 4 as in the existing way to generate steam, and this steam is supplied to a heat demand 22, as well as part of the steam is fed through a conduit 7 to a steam refrigerator 8, where the steam is heat-exchanged to obtain cooling water.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention recovers waste heat from a prime mover using two types of heat, cold heat (cold water) and hot heat (steam), and is able to cope with seasonal fluctuations in demand for cold and hot heat. The present invention relates to an exhaust heat recovery system for a cozy energy resin system that can improve exhaust heat recovery efficiency throughout the year by adjusting the distribution of cold and hot heat accordingly.

[Conventional technology]

BACKGROUND ART A cogeneration system that supplies cold and hot demand by recovering exhaust heat from a power generator (prime mover) that drives a generator or the like has been systemized in energy plants and the like. When recovering exhaust heat from a prime mover (representing a diesel engine or gas engine, hereinafter referred to as the "engine"), cold heat recovery can be performed by adsorption using engine cooling water or by a hot water refrigerator (hot water refrigerator). Heat exchanged cold water is used as a medium, and thermal heat recovery is performed using steam obtained from engine exhaust gas by an exhaust heat recovery boiler as a medium. There are also examples where cold heat recovery is performed using steam as a medium.

[Problem to be solved by the invention]

The seasonal demand for cold and hot water tends to increase in the summer because the demand for cold and hot water is mainly for air conditioning, while the demand for hot water tends to decrease in the summer. Therefore, in the summer when the demand for heat is low, 100% of the steam may not be recovered and may be disposed of. Furthermore, in hot water refrigerators, there have been cases where cold water has been disposed of due to excessive supply of cold water due to a decrease in demand for cold heat, and conventional systems have had the problem of not being able to efficiently recover heat.

Therefore, the purpose of this invention is to recover engine exhaust heat from cold heat (
It uses two types of heat (chilled water) and heat (steam), and adjusts the distribution of cold and hot heat according to seasonal changes in demand for cold and hot water, improving waste heat recovery efficiency throughout the year. Our objective is to provide an exhaust heat recovery system for a cogeneration system that can.

[Means to solve the problem]

The gist of this invention is as follows.

fl) A cord that collects exhaust gas from the prime mover by using steam obtained from an exhaust gas recovery boiler as a medium to meet the heat demand, sends the cooling water of the prime mover to a hot water refrigerator, and uses cold water obtained from the hot water refrigerator as a medium to meet the cold heat demand. In the generation system, the cooling water is heated through an air cooler of the prime mover and sent to the hot water refrigerator;
A high-efficiency exhaust heat recovery system for a cogeneration system, characterized in that the exhaust heat recovery efficiency of the hot water refrigerator is improved by the cooling water heated by the air cooler.

(2) An exhaust heat recovery boiler is connected to the prime mover, and the steam obtained from the exhaust gas by the exhaust heat recovery boiler is used as a medium to meet heat demand, while a hot water refrigerator that uses the cooling water of the prime mover is connected to the prime mover. , supplying the cold water demand as a medium using the cold water obtained by the hot water refrigerator, and connecting a steam refrigerator to the exhaust heat recovery boiler, and supplementally supplying the cold water demand as a medium with the cold water obtained from the steam refrigerator; Furthermore, the high efficiency of the cogeneration system is characterized in that the heat exchange efficiency of the hot water refrigerator is improved by raising the temperature of the cooling water via an air cooler of the prime mover and sending the heated water to the hot water refrigerator. Exhaust heat recovery system.

In the present invention, a hot water absorption (or adsorption) refrigerator (hereinafter referred to as a "hot water refrigerator") uses engine cooling water as a heat source water.
Improve the heat exchange efficiency (coefficient of performance (hereinafter referred to as r))
In order to improve the hot water temperature (referred to as "cOP"), we decided to raise the temperature of the hot water of the heat source water even higher, and as a means of doing so, we did not send the cooling water directly to the heat exchanger of the hot water refrigerator, but instead sent the cooling water to the engine's air cooler midway. Send via. As a result, the cooling water becomes even hotter due to heat exchange with the high-temperature air in the air cooler, and the heat source water of the hot water refrigerator becomes hotter than when cooling water is directly supplied to the heat exchanger. CO of
P will improve. Furthermore, a steam-type absorption chiller (hereinafter referred to as "steam-type chiller") is connected to the exhaust heat recovery boiler, and a part of the steam obtained from the engine exhaust gas is supplied to this steam-type chiller. This will replenish the shortfall in heating and cooling demand during the summer when demand is high.

Next, the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 are system diagrams showing one embodiment of the system of the present invention. FIG. 2 shows FIG. 1 in more detail, and the numbers in the figure correspond to those in FIG. 1. In FIG. 2, 39 is a return tank, 40 is a water supply pump, and 41 is a conduit. In this embodiment, the generator l
A diesel engine is used as the prime mover (hereinafter referred to as "engine 2"). A gas engine can also be used as the engine.

In the drawing, 4 is an exhaust heat recovery boiler, and 8 is a steam refrigerator, which are connected to each other by conduits 5, 6, and 7.

9. IO is a steam flow rate control valve. 38 is an exhaust gas pipe, and exhaust gas is discharged from a chimney (not shown). 13
is a jacket cooling water cooler, 16 is a lubricating oil cooler, 19 is
are air coolers, each connected to the engine 2 by a conduit If 14.17. 20 is a cooling system;
21 is a conduit for circulating the water cooled by the cooling system 2° to the air cooler 19, lubricating oil cooler 16, and Noyakette cooler 13; 25 is a pump; 26 is a temperature control valve;
37 is a calorimeter. The jacket cooler 13, the lubricating oil cooler 16 and the air cooler 19 are each part of a cooling system 20.
It is cooled by a water cooling system that circulates water cooled by a conduit 21. 27 is a hot water refrigerator, 2
8 is a heat exchanger of the hot water refrigerator. 12 is a conduit through which heat source water circulates, and 24 is a heat source hot water circulation pump.

The cooling water conduit 11a on the outlet side of the engine 2 branches into a conduit 30 in the middle thereof. Branched conduit 30a (
The part in the middle is cut with * mark) is air cooler 19
It is connected to the·. Further, the conduit 30b is connected to pass through the air cooler 19 and then through the heat exchanger 28. Furthermore, a conduit 30c (the middle part is shown cut with a mark **) is connected from the heat exchanger 28 to the conduit 11b. Reference numeral 15 denotes a temperature control valve for controlling the engine outlet temperature, which is installed at the branching point of the conduit 11a and the conduit 30b. 31.32
．． Reference numeral 33 is a conduit for supplying cold water, which has undergone heat exchange with the steam refrigerator 8 and the hot water refrigerator 27, to the cooling demand (mainly for cooling) 23. 34 is a controller that controls each temperature control valve, pump, etc., and 35 is a signal line.

[Effect]

Engine cooling water is supplied to the air cooler, heated by the high temperature air of the air cooler, and then supplied to the heat exchanger, improving the heat exchange efficiency of the hot water refrigerator. Furthermore, the engine exhaust gas is supplied to the exhaust heat recovery boiler, and a portion of the recovered steam is supplied to the steam refrigerator for heat exchange, thereby improving the heat exchange efficiency of the entire system.

〔Example〕

Next, the present invention will be explained with reference to examples.

This example is a system that generates electricity with a generator and supplies it to the demand load as engine exhaust heat and cold heat.
As shown in Figures 1 and 2, this is an example of operation during the summer season, when the demand for cold heat (load) is high when exhaust heat is recovered from both the hot water chiller and the steam chiller. ,
Cooling water for the engine 2 is circulated through a conduit 11.

The engine outlet temperature (indicated by TI) is maintained at a predetermined temperature. Furthermore, the cooling water for the engine 2 is supplied to the hot water refrigerator 27.
The conduit 30 is connected to the heat exchanger 28 via the air-quench cooler 19.
Supplied through. The cooling water is supplied to the air cooler 19 through a conduit 30a branched from the middle of the conduit 11a, and is heated to a temperature higher than T1 (indicated by T2) by the high temperature air of the air cooler 19. The cooling water is then supplied from the air cooler 19 through the conduit 30b to the heat exchanger 28 at a high temperature (T2). In this way, by supplying cooling water at high temperature, the coefficient of performance (CO
P) is improved.

After the heat exchange has been completed, the cooling water passes through the conduit 30c to the conduit 1.
It merges with 1b and returns to engine 2. Temperature adjustment at this time is controlled by a controller 34 that receives signals from thermometers placed in each section.

On the other hand, exhaust gas from the engine 2 is supplied to the exhaust heat recovery boiler 4 via the exhaust gas pipe 38. The steam recovered by the waste heat recovery boiler 4 is mainly supplied to the thermal demand 22 via the conduit 56. A part of the water is then supplied to a steam refrigerator 8 via a conduit 7, where heat is exchanged to obtain cold water. The amount of steam supplied to the steam refrigerator 8 is controlled by a flow control valve 10.

The cold water that has undergone heat exchange with the steam refrigerator 8 and the hot water refrigerator 27 is supplied to the cold heat demand 23 through the conduits 31 and 32 and the confluent conduit 33. In the conduit 33, the cold water flow rate (
The amount of cold heat required) is measured by the calorimeter 36. The demand for cold heat (chilled water) is first supplied by the hot water refrigerator 27, and this is a graph showing the supply and demand situation of warm heat by the steam refrigerator 8 in the case of a shortage. As shown in the drawing, the supply to the demand for cold pigeons by hot water refrigerators is assumed to be constant throughout the four seasons. During periods when the demand for cold energy is large, such as around summer, the insufficient supply of the demand for cold energy by the irrigation type refrigerator can be covered by the supply of the demand for cold energy by the steam type refrigerator. In other words, this system can stably supply a constant amount of cold water through the hot water chiller throughout the year, and can control the flood control supply using the steam chiller in response to fluctuations in demand for four types of heat.

Next, an example of operation in the case of controlling the amount of cold water heat of the hot water refrigerator when the cold demand (load) decreases is as follows.

L When the demand side load of cold energy decreases, first the steam chiller 8
Control (reduce) the amount of steam supplied to the saltwater refrigerator 27 with the flow control valve 10. ■2 If the demand-side load further decreases, in order not to deteriorate the waste heat recovery efficiency (COP) of the salt water refrigerator 27, In order not to lower the heat source hot water temperature (indicated by Ti) from the desired temperature, and the temperature difference ΔT (
In order to keep Ti-TO constant, the amount of heat recovered by the hot water refrigerator 27 is controlled. The method is as follows.

(2) Measure the cold heat demand with the calorimeter 36 or set it externally, and input the signal to the control 34. ■■, Control the flow rate of the heat source hot water circulation pump 24. ■■, Control the opening degree of the temperature control valve of the jacket cooling water engine outlet plate and adjust the flow rate of the cooling water to maintain TI.
2■ ■, the temperature at the outlet of the air cooler 19 (T
03. At this time, in order to protect the engine 2 and ensure stable operation, the following settings are made.

■Measure the air temperature of the air cooler 19 with a thermometer 37,
The amount of cooling water in the water cooling system is controlled by the temperature control valve 42 to keep it around the desired temperature (indicated by T3), and the engine outlet temperature of the jacket cooling water is adjusted to the desired temperature (indicated by TI).
Keep it. This method is carried out in the following steps (a) and (b).

(a) The amount of cooling water in the air cooler 19 is controlled according to the temperature of the air in the air cooler 19.

1bl-, jacket cooling water engine outlet temperature (Tl)
Included in ◎, which detects and controls the distribution of cooling water to the air cooler 19 and jacket cooling water cooler 13.

For stable operation, each engine load (e.g.
3/4.2/4), the exhaust heat recovery heat amount, the cold heat demand, and the opening degree of each temperature control valve at that time are set.

When operating this system, the generation capacity of generator 1 to meet the power demand should be sufficiently larger than the capacity of generator l, or it should be set to a constant output with a margin compared to the demand. , This makes it easier to respond to fluctuations in demand for cooling and heating.

When assigning control priorities to the control method described in 2 above, the order is as follows, based on the quickness of the system's time response.

By performing the control as described above, waste such as disposal due to excessive supply of cold water when the demand for cold water decreases is reduced, and high efficiency of the entire system can be realized.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the following useful effects.

l By passing jacket cooling water through the air cooler, the temperature of the high-temperature heat source water of the hot water refrigerator increases, making it possible to efficiently obtain cold water and improving the efficiency of exhaust heat recovery by the hot water refrigerator.

2ii! By supplementing cold demand with a steam chiller, which has better exhaust heat recovery efficiency than a water chiller, the exhaust heat recovery efficiency for the entire cold heat demand is improved. By the way, in the steam type refrigerator mentioned in 7, "COP # 1.3 J, whereas in the irrigation refrigerator with hot water of 85℃, rcopξ
0.7", and can respond stably and efficiently to the demand for heating and cooling in the summer.

[Brief explanation of drawings]

It is a graph showing the supply and demand status of cold and hot heat when the vehicle is operated. In the drawing: 111 Generator, 2 - Engine, 5.6.7.11.12.14.17.21.30.3
1.32.33-Conduit, 4-1 Exhaust heat recovery boiler, 81. -Steam type refrigerator, 9.10-, -Steam flow rate control valve, 13-Jacket cooling water cooler, 15.26.42-Temperature control valve, 161. - Lubricating oil cooler, 19- Air cooler, 20- Cooling system, 22- Heating demand, 23-1, Cold demand, 24-0. Heat source hot water circulation pump, 25- pump, 27- hot water refrigerator, 28- heat exchanger, 34- controller, 35- signal line, 36-5- calorimeter, 371. - Thermometer, 38 - Exhaust gas pipe, 39 - Return tank, 40 - Water supply pump, 41 - Conduit. Procedural amendment (spontaneous) Indication of the case Patent application No. 2778 Name of the invention Person making amendments to high-efficiency waste heat recovery system for cogeneration system Relationship to the case Patent applicant address 1-1-2 Marunouchi, Chiyoda-ku ( name) (
412) Representative of Nippon Kokan Co., Ltd. Akinari Yamaguchi

Claims (1)

[Scope of Claims] 1. Exhaust heat recovery from a prime mover is performed using steam obtained from an exhaust gas recovery boiler as a medium to meet thermal demand, and cooling water of the prime mover is sent to a hot water refrigerator, and cold water obtained from the hot water refrigerator is used as a medium. In a cogeneration system that serves cold demand, the cooling water is heated through an air cooler of the prime mover and sent to the hot water refrigerator, and the cooling water heated by the air cooler cools the hot water refrigerator. A high-efficiency waste heat recovery system for a cogeneration system, which is characterized by improving the waste heat recovery efficiency of a cogeneration system. 2. An exhaust heat recovery boiler is connected to the prime mover, and the steam obtained from the exhaust gas by the exhaust heat recovery boiler is used as a medium to meet the heat demand. On the other hand, a hot water refrigerator using the cooling water of the prime mover is connected to the prime mover, and the The cold water obtained by the hot water refrigerator is used as a medium to meet the cold demand, and a steam chiller is connected to the exhaust heat recovery boiler, and the cold water obtained from the steam chiller is used as a medium to supplementally serve the cold demand, and further, High efficiency waste heat of a cogeneration system, characterized in that the heat exchange efficiency of the hot water refrigerator is improved by raising the temperature of the cooling water through an air cooler of the prime mover and sending it to the hot water refrigerator. collection system.