JPH04281165A - cogeneration system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving technique for an absorption chiller used for air conditioning and the like. More specifically, the present invention relates to an absorption refrigerator used as a means of waste heat recovery in a cogeneration system.

0002

BACKGROUND OF THE INVENTION As a recent trend, various cogeneration systems for the purpose of energy saving have been actively developed. A cogeneration system uses a prime mover such as a diesel engine, gas engine, or gas turbine as a driving source to generate electricity in-house, and also uses waste heat from the prime mover to perform heating, hot water supply, and cooling. This is a so-called combined heat and power generation system that aims to utilize energy efficiently and effectively. Among these cogeneration systems, the heat sources targeted for waste heat recovery in cogeneration systems equipped with a generator driven by a stationary water-cooled prime mover such as a diesel engine or gas engine are combustion waste gas and the engine. There is a cooling water temperature. Currently, the thermal energy of engine cooling water is usually recovered as hot water and used as it is as a heat source for space heating, hot water supply, and absorption chillers.

0003

[Problems to be Solved by the Invention] By the way, the efficiency of this absorption chiller generally improves as the input temperature increases. There is a limit to the heat input temperature to the refrigerator, so increasing the efficiency of absorption refrigerators is inevitably subject to certain restrictions. Therefore, in order to solve the problem of increasing the efficiency of the absorption chiller in the above-mentioned cogeneration system, the present inventors attempted various studies and research, and as a result, they recovered the waste heat of engine cooling water as low-pressure steam, and recovered the waste heat of engine cooling water as low-pressure steam. The present invention was completed based on the discovery that the efficiency of an absorption chiller can be further improved by using water vapor as a heat source for the absorption chiller.

That is, the present invention recovers the thermal energy of cooling water as latent heat through a heat exchanger to the steam side, uses the steam as a heat source for an absorption refrigerator, and converts it into sensible heat. The aim is to further improve the thermal efficiency of absorption chillers while using water vapor as a buffer.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following constituent elements. A cogeneration system comprising a generator driven by a stationary water-cooled engine, wherein the temperature of the cooling water of the engine is set to 110 to 140°C at the outlet thereof.
What is claimed is: 1. A cogeneration system comprising: an absorption chiller that maintains the temperature within a range of 0.1 and uses water vapor recovered from the high-temperature cooling water via a heat exchanger as a heat source.

[0006]

[Operation] Generally, the type of prime mover installed in the cogeneration system equipped with a generator driven by a stationary engine of the present invention may be a water-cooled diesel engine or a gas engine, and its power is Usually 2
Those with the ability to drive a generator of about 00 to 600 kW are widely used. In the cogeneration system described above, in order to recover the waste heat of the engine cooling water as steam, it is necessary to raise the temperature of the diesel engine cooling water to 100° C. or higher. However, it is desirable that the upper limit of the cooling water temperature be approximately 140° C. in order to avoid maintenance and servicing problems such as deterioration of the lubricating oil and shortening of the engine's non-operating period.

[0007] Cooling water for a diesel engine normally circulates in a pressure-tight sealed flow path that includes a water jacket, a circulation pump, a radiator, and the like. The temperature of the cooling water near the cooling water outlet of the diesel engine is usually about 110 to 140°C, preferably about 110 to 130°C. The pressure of the steam that can be recovered from here varies depending on the type of stationary water-cooled engine, its capacity, operating conditions, etc.
It is usually about 0.3 to 1.0 Kg/cm2.G. The absorption refrigerating machine installed in the present invention has no difference in basic structure from that of a commonly used absorption refrigerating machine, and as a typical example, it uses pure water as a refrigerant and as an absorption liquid. An example is an absorption refrigerator using a lithium bromide (LiBr) aqueous solution.

FIG. 2 shows a general flowchart in the absorption refrigerator. The outline of its action will be explained below. In the figure, an absorption refrigerator 25 includes (1) an absorber 2 containing an aqueous lithium bromide solution 1, an aqueous lithium bromide solution that has become a dilute solution by absorbing pure water as a refrigerant (hereinafter referred to as refrigerant); 3, a condenser 5 for condensing the refrigerant vapor generated in the regenerator 4, and an evaporator 6 for producing cold water used for cooling using the latent heat of vaporization of the refrigerant.

(2) To explain the flow of refrigerant in the refrigerator 25, the refrigerant evaporated in the evaporator 6 is as follows:
The lithium bromide aqueous solution 1 in the absorber 2 that has moved through the pipe to the absorber 2 side and absorbed the refrigerant is sent to the absorption liquid pump 7.
It is sent to the heat exchanger 8, where it is heat exchanged with the high temperature aqueous lithium bromide solution concentrated and regenerated in the regenerator 4, and its temperature is raised. The heated lithium bromide aqueous solution is sent to the regenerator 4, where it is heated by a heat source 9 to evaporate the refrigerant and is concentrated and regenerated. The regenerated concentrated lithium bromide aqueous solution is cooled via the heat exchanger 8 (exchanging heat with the diluted lithium bromide aqueous solution sent by the pump 7), and then sent to the absorber 2 side.

On the other hand, the refrigerant vapor evaporated in the regenerator 4 moves through the pipe to the condenser 5 side.
It is cooled by the cooling water 10 flowing inside the pipe and condenses.
stay. The condensed refrigerant is sent to the evaporator 6 side, and the refrigerant is circulated therein by a refrigerant pump 11. In this evaporator 6, the evaporated refrigerant is absorbed by the lithium bromide aqueous solution in the absorber 2, so that a so-called vacuum state is created, and thereby the refrigerant is evaporated at a low temperature. Also,
The latent heat of vaporization of the refrigerant cools the cold water 12 passing through the pipe, which is used for cooling.

In the above-mentioned absorption refrigerator, the present invention utilizes heat from the engine cooling water of a cogeneration system equipped with a generator driven by the above-mentioned stationary water-cooled engine as the heat source 9 of the regenerator 4. This method is characterized by using recovered water vapor. Absorption refrigerators are divided into single-effect cycle types and
Although the absorption refrigerator of the present invention is broadly classified into the more efficient double-effect cycle type, the single-effect cycle type is used due to the pressure constraints of the heat-recovered steam as a heat source.

0012

[Embodiments] Examples of the present invention will be described below with reference to the drawings, but each member constituting the present invention can be modified in various ways based on the technical level generally known in the industry at the time of filing. Therefore, it is not permissible to understand the gist of the present invention in a limited manner based only on these Examples. Figure 1 shows the schematic flow of a cogeneration system configured by connecting a diesel engine with a displacement of 18 liters to a generator with a power generation capacity of 280 kW. In the figure, the cogeneration system includes a generator 21, a diesel engine 22, a jacket reboiler 23, a gas-liquid separator 24, and a single-effect absorption refrigerator 25, respectively.

[0013] Diesel engine 22 using light oil as fuel
By operating the generator 21, the generator 21 is operated to generate electricity. The combustion waste gas of the diesel engine 22 is discharged into the atmosphere after its waste heat is recovered by a waste heat boiler (not shown). On the other hand, the engine cooling water 26 is circulated in a pressurized flow path using a cooling water circulation pump (not shown) to cool the diesel engine 22, and the heated cooling water is transferred to the jacket reboiler 22.
used as a heat source. This circulation of the cooling water 26 is carried out in a pressure-resistant sealed flow path in order to maintain the water temperature after engine cooling to 100°C or higher (in the case of an open flow path, the boiling water temperature is 100°C or higher).
00℃ or higher), the temperature of the cooling water is (
For example, by providing a thermo valve that opens at 120° C. in the flow path, the temperature is controlled to 120° C. on the inlet side of the jacket reboiler 23.

The boiler water 27 passes through the jacket reboiler 23 and is heated up, where it becomes steam 28, and then sent to the gas-liquid separator 24, where it is separated into gas and liquid. The liquid boiler water 27 from which the water vapor has been separated is circulated by a boiler water circulation pump (not shown) and sent to the jacket reboiler 23 again, and the same process is repeated. On the other hand, the water vapor 28 from which the liquid has been separated by the gas-liquid separator 24 is sent to a single-effect absorption refrigerator 25 whose flow is roughly shown in FIG.
used as.

The pressure of the steam used as the heat source 9 was controlled to be 0.6 kg/cm 2 ·G. Further, the engine cooling water 26 and boiler water 27 are
It will be replenished accordingly. Next, the heat balance in this cogeneration system will be explained.

Table 1 shows the heat balance in the jacket reboiler 23.
Table 1
Inlet/outlet temperature (℃) Flow rate (Kg/H)
Heat amount (Kcal/H) Cooling water side
120/115 17,300
87,500 Boiler water side 53
/114 135
80,200

The steam at a pressure of 0.6 Kg/cm 2 ·G obtained by recovering heat from the high-temperature cooling water 26 by the jacket reboiler 23 is used to regenerate the single-effect absorption chiller 25 with the flow roughly shown in FIG. The single-effect absorption refrigerator 25 was operated by supplying it as the heat source 9 of the container 4, and a cooling capacity of 58,541 Kcal/H was obtained. In this case, the energy efficiency is calculated using the following formula: 0.
73, which shows that the energy efficiency is significantly improved compared to the energy efficiency of about 0.6 to 0.65 of absorption chillers that use hot water as a heat source used in conventional cogeneration systems. .

Calculation formula for energy efficiency: η=(Ti-To)×Q/C Where: η: Energy efficiency Ti: Evaporator inlet temperature of circulating water for cooling (15°C) To:
Evaporator outlet temperature of circulating water for cooling (8℃) Q: Circulation amount of circulating water for cooling (8,363 Kg/H) C: Heat input to absorption chiller (80,200 Kcal/H)
η=(15-8)×8,363/80,200≒0.
73

[0019]

Effects of the Invention: In a cogeneration system equipped with a generator driven by a stationary water-cooled engine, engine cooling water waste heat is recovered by converting it into water vapor, and the thermal relationship between the two is By using it as a heat source that also serves as a buffer material, it is possible to use an absorption chiller that uses water vapor at a higher temperature than conventional hot water as a heating source, improving the efficiency of the chiller and improving overall efficiency compared to conventional equipment. We were able to obtain a highly efficient cogeneration system.

[Brief explanation of the drawing]

[Figure 1] Schematic flow diagram of the cogeneration system of the present invention

[Figure 2] Schematic structural diagram of a single-effect absorption chiller

[Explanation of symbols]

1 Lithium bromide aqueous solution 2 Absorber 3. Lithium bromide dilute solution 4 Regenerator 5 Condenser 6 Evaporator 7 Absorption liquid pump 8 Heat exchanger 9 Heat source 10 Cooling water 11 Refrigerant pump 12 Cold water 21 Generator 22 Diesel engine 23 Jacket reboiler 24 Gas-liquid separator 25 Single-effect absorption refrigerator

Claims (1)

[Claims] Claim 1: A cogeneration system comprising a generator driven by a stationary water-cooled engine,
The cooling water temperature of the engine is set to 11 at its outlet.
A cogeneration system characterized by comprising an absorption refrigerator that maintains the temperature within a range of 0 to 140°C and uses water vapor recovered from the high temperature cooling water via a heat exchanger as a heat source.