JPS5815705B2 - Heat recovery method in power generation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat recovery method for recovering and utilizing waste heat from power generation equipment.

In conventional power generation equipment, the purpose was simply to obtain the necessary electric power, and the waste heat from the generator prime mover of the power generation equipment 1 was wasted into the atmosphere or cooling water, as shown in FIG.

However, the thermal efficiency of power generation equipment 1 is about 10 to 40%,
The remaining 60-90% of the energy was wasted as waste heat.

For this reason, the cost of electricity for small-scale power generation facilities was extremely high, and it was not possible to buy electricity right away, so it was only used for areas without electricity supply or as emergency power generation facilities.

In order to effectively utilize this waste heat, it has been considered to supply it to an attached absorption chiller, but the control is complicated, the operation is unstable, and the equipment is large. However, there were disadvantages such as high equipment costs.

The inventors conducted extensive research to eliminate these drawbacks, and found that in small-scale power generation facilities, of the power demand within the area to be supplied, most of the fluctuating power is accounted for by the power consumption of the cooling equipment, and other power consumption is We focused on the fact that the power consumption of motive power, lighting, etc. is almost constant, and therefore the amount of power generated increases or decreases linearly with the increase or decrease in the power consumption of the air conditioner, and after repeated studies we came up with the present invention. It is a sure thing.

The technical idea of the present invention is that the heating source of an absorption refrigerator placed on the high temperature side with respect to the flow of refrigerant fluid is not sourced from outside the system, but is a compression type refrigerator placed on the low temperature side within the same system. The goal is to recover heat from the waste heat of the power generation equipment that supplies the power, and by providing a configuration that embodies this, the above-mentioned drawbacks of conventional ones can be eliminated, the control mechanism can be simplified, and the system can be stabilized. To provide a heat recovery method for power generation equipment, which can reduce the size of scales and absorption refrigerators, reduce equipment costs, and enable practical and economical operation even in small-scale power generation equipment. It is an object.

The present invention provides a heat recovery method for a power generation facility that meets the power demand of a compression chiller, including recovering waste heat from the power generation facility and using it as a heating source for a generator of an absorption chiller.
Heat recovery in a power generation facility, characterized in that the cold medium returned from the cooling load is first guided to the absorption chiller and cooled, then guided to the compression chiller and cooled, and then supplied to the cooling load. It's a method.

FIG. 2, which describes an embodiment of the present invention with reference to the drawings, shows waste heat (heat absorbed in exhaust gas and cooling water) of a prime mover, generator, etc. of a power generation facility 1 being collected by a heat recovery device 2. An example of the heat balance when recovered and used as a heat source to improve thermal efficiency is shown below.

FIG. 3 shows the main configuration of the embodiment. The power generation equipment 1 consists of a generator 3 and a prime mover 4, and forms a power generation set together with a heat recovery device 2 that recovers waste heat generated from the power generation equipment 1. , an absorption refrigerator 5 and a compression refrigerator 6 connected in series on the downstream side of the absorption refrigerator 5 form a refrigerator set, which is equipped with a heating and hot water supply set mainly including a heat exchanger T, and a cooling It is connected to attached equipment such as a tower 8 and a circulation pump 9 through appropriate piping to form an energy recovery system.

In order to obtain the electric power necessary for the electric power load in the area, the waste heat generated when operating the prime mover 4 and generator 3 of the power generation equipment 1 is transported by exhaust gas, cooling water, cooling air, etc., and is transferred to the heat recovery device 2. , it moves to the heating medium and generates vapor of the heating medium.

During cooling, this steam is led to the absorption refrigerator 5 through the pipe 11, enters the generator 12, is used as a heat source, and is sent to the receiver 2.
1 and then returned to the heat recovery device 2. In other words, waste heat from the power generating equipment is used as a heating source for the absorption chiller 5 to power the compression chiller installed on the low-temperature side within the same system, rather than outside the system. The recovered heat is used.

The absorption refrigerator 5 is provided with a bypass 15 for bypassing the liquid refrigerant between the condenser 13 and the absorber 14, and a bypass valve 16 operated by the pressure of the pipe 11.

When the amount of waste heat recovered by the power generation set is greater than the amount of heat consumed by the absorption refrigerator 5 for cooling and load, the vapor pressure in the pipe 11 increases.

This pressure increase opens the bypass valve 16, increasing the apparent load on the absorption refrigerator 5 and absorbing waste heat.

Conventionally, there is an imbalance between the waste heat of the power generation set and the heat consumption of the absorption chiller, and a separate heat exchanger, cooling tower, etc. is required to discharge this surplus waste heat to the outside of the system. In addition to the amount of heat required to meet the load of the absorption chiller, a control device was required to control the amount of heat discharged outside the system.

This requires extra dedicated heat exchangers, cooling towers, and extremely complex and expensive control equipment, contributing to increased equipment costs.

In contrast, in this embodiment, an absorption refrigerator with a bypass valve (
By applying the residual waste heat of the generator cellar and (If the absorption chiller has full capacity, the absorption chiller has full capacity.) Through the cycle of the absorption chiller, exhaust heat can be discharged from the cooling tower of the absorption chiller to the outside, making it economical as there is no need for a heat exchanger, cooling tower, or control equipment dedicated to waste heat. , and has the advantage of easy operation control.

In the refrigerant fluid (chilled water) system for refrigeration loads, the fourth
As shown in the figure, an absorption refrigerating machine 5 and a compression refrigerating machine 6 are inserted in series, and the absorption refrigerating machine 5 is placed on the high temperature side (upstream side) of the compression refrigerating machine 6 for selling cold water. .

As a result, the following effects can be achieved.

(1) The absorption refrigerator 5 can be made smaller.

The refrigerating capacity of the absorption refrigerator 5 increases or decreases depending on the temperature of the cold water outlet.

In contrast to ensuring a constant refrigeration capacity, the size of the absorption refrigerator 5 can be made smaller if the cold water outlet temperature is higher.

By arranging the absorption refrigerator 5 on the upstream side of the compression refrigerator 6 with respect to the flow of the refrigerating medium fluid, the cold water outlet temperature becomes high, and miniaturization can be achieved.

(2) In the absorption refrigerator 5, the control mechanism from the load circuit, that is, the chilled water outlet temperature control mechanism can be omitted, the control mechanism becomes simple, and the system 75E6 is self-balanced, which is extremely stable.

To ensure stable cooling operation when there is a cooling load,
It is necessary to control the capacity of the refrigerator set depending on the load condition.

When two refrigerators are installed in series, the temperature of the cold water supplied to the load must be controlled, so at least the downstream (low-temperature side) compression refrigerator 6 must be controlled by capacity control. Chilled water outlet temperature control shall be carried out;
Through this cold water source temperature control, the capacity of the compression refrigerator 6 increases or decreases in accordance with an increase or decrease in the cooling load, and its power consumption increases or decreases.

On the other hand, in small-scale power generation facilities, the power demand within the area to which electricity is supplied, other than the power for the cooling equipment, for example, other motive power, lighting, etc., is almost constant, so the increase or decrease in the amount of power generation depends on the This occurs due to an increase or decrease in the power consumption of machine 6.

That is, if there is an increase or decrease in the cooling load, there will be an increase or decrease in the power consumption of the compression refrigerator 6, which will cause an increase or decrease in the amount of power generation.

As the amount of power generation increases or decreases, the amount of exhaust heat also increases or decreases, and therefore the steam pressure generated in the heat recovery device 2 also increases or decreases, and the pressure and temperature of the steam supplied to the absorption refrigerator 5 increases or decreases.

At this time, the relationship between the load fluctuation of the generator 3 and the generated steam pressure is almost a linear relationship, as shown in FIG.

On the other hand, since the absorption refrigerator 5 bears the cooling load together with the compression refrigerator 6, it is necessary to increase or decrease the refrigerating capacity of the absorption refrigerator 5 in accordance with an increase or decrease in the cooling load.

To increase or decrease the refrigerating capacity of the absorption refrigerator 5, the heating vapor pressure (temperature) is increased or decreased.

In this case, the load fluctuation that should be borne by the absorption chiller 5,
The relationship between the required steam pressure and the required steam pressure is almost a straight line as shown in Figure 5.The straight line between the generator load fluctuation and the generated steam pressure is the straight line between the absorption chiller load fluctuation and the required steam pressure. (absorption chiller load characteristics).

When the load 17 increases or decreases, the capacity of the compression refrigerator 6 is first controlled (as described later, the absorption refrigerator 5 is not controlled from the load circuit, such as chilled water temperature control).
, the power consumption of the compression refrigerator 6 increases or decreases, the amount of power generation increases or decreases, the amount of exhaust heat increases or decreases, the generated steam pressure increases or decreases, and the absorption refrigerator 5 increases or decreases.
refrigeration capacity increases or decreases.

As mentioned above, the load characteristics of the absorption chiller match well with the relationship between the generator load fluctuation (that is, the load variation of the compression chiller 6) and the generated vapor pressure. Appropriate refrigeration capacity is automatically obtained and the system maintains self-equilibrium without any capacity control.

Therefore, the complicated control mechanism in the absorption refrigerator becomes extremely simple, and not only the equipment cost is reduced, but also the system becomes self-stabilizing, and the operation becomes extremely stable.

If it is assumed that the absorption refrigerator 5 is disposed on the downstream side (low temperature side) of the compression refrigerator 6, disadvantages opposite to the above-mentioned advantages will arise.

That is, regarding (1), the size of the absorption refrigerator 5 increases.

Regarding (2), when the absorption chiller 5 is installed downstream, it is necessary to stably supply chilled water at a predetermined temperature to the load even when the load fluctuates, so two chiller sets are required. The temperature at the outlet of the absorption chiller 5, that is, the chilled water outlet temperature of the absorption chiller 5 on the downstream side, must be detected to control the capacity of the absorption chiller 5 (for example, controlling the large valve flow rate of heated steam to the generator 12).

However, in this case, let us assume that the compression refrigerator 6 is not controlled from the load circuit.

- If the load increases or decreases in such a state, the amount of steam supplied to the absorption chiller 5 will be increased or decreased to increase or decrease the refrigerating capacity.

However, since the compression chiller 6 is not controlled by the load circuit, there is no increase or decrease in its refrigeration capacity, and therefore constant energy is given to the absorption chiller 5 without any increase or decrease in power consumption, power generation, or amount of exhaust heat. .

In the case of an increase in load, the energy delivered to the absorption refrigerator 5 must be increased.

However, since this energy is constant, there is a shortage and it is not possible to maintain self-balance.

Therefore, it is necessary to control the compression chiller 6 on the high temperature side from the load circuit, and in the end, both the absorption chiller 5 and the compression chiller 6 require a control mechanism from the load circuit, that is, the chilled water outlet temperature. A control mechanism is required, making the structure complicated.

Conversely, even in the load range, if the capacity of the compression chiller is constant, there will be no decrease in power consumption, power generation, or exhaust heat, and the energy given to the absorption chiller 5 will still not decrease. This means that excessive energy will continue to be applied to the refrigeration capacity that should be burdened by the refrigerator.

This excessive energy is generated by supplying excessive power to the load, and this excessive energy is discharged outside the system, resulting in unnecessary energy loss.

In order to prevent this loss, it is necessary to control the compression chiller 6 from the load circuit, and both chillers ultimately require a control mechanism from the load circuit, that is, a chilled water outlet temperature control mechanism. A mechanism for switching between the two is also required, making the structure extremely complicated.

The above is the explanation regarding the effects (1) and (2).

The yarn paths for heating loads and hot water loads will be explained.

During heating and hot water supply, steam from the heat recovery device 2 is guided to the heat exchanger 7, and the heat recovered by the heat recovery device 2 is converted into hot water for a load 18 as a heating load or a hot water supply 19 as a hot water load. give.

It is not desirable for heat medium management to flow directly to the load side, and depending on the type of heat medium, it may be harmful to employees, employees, and animals, so an indirect method using heat exchanger T as described above is recommended. is desirable.

This heat exchanger 7 is provided with a heat balancer, and the pipe line 20
It is connected to the cooling tower 8 by.

If the load decreases and the balance with the amount of waste heat is lost, the temperature of the secondary heat medium such as hot water or hot air will rise excessively, so the heat balancer is used to radiate heat.

In the system of this embodiment, the waste heat of the power generation equipment 1 is recovered by the heat recovery device 2, and is transferred to the absorption refrigerator 5, the hot water supply 19,
It can be used as a heat source for loads 18 for air conditioning equipment and processes, or indirectly as a cold source for loads 17 such as air conditioners and refrigeration, to increase overall efficiency, and can even be increased to a maximum coefficient of 75. be.

In addition, even if the power generation load increases and the waste heat from the power generation equipment increases, the bypass 15 installed in the absorption chiller 5 in the case of a cooling cycle or the heat balancer in the case of a heating cycle will automatically overheat the power. Load can be prevented, allowing safe and smooth operation.

Generally, the waste heat of the prime mover for power generation is normally used only as hot water (around 90°C), but in this example system, the heated cooling water of the prime mover is reheated by the exhaust gas of the prime mover, and the waste heat is converted into steam. This makes it possible to greatly increase the recovery rate of waste heat from 15% to 40% of input, and since waste heat can be recovered as steam, waste heat can be used for heating and space heating. In addition to being able to operate an absorption chiller, the capacity of the centrifugal chiller and generator can be reduced, reducing the overall equipment and eliminating the need for an extra dedicated heat exchanger that was previously required. , it eliminates the need for coolers and extremely complex and expensive control devices, and makes full use of the excess capacity of the absorption chiller to transfer surplus waste heat from the power generating equipment to the outside through the absorption chiller's cooling tower through the absorption chiller cycle. This makes it possible to eliminate heat exchangers, coolers, and control equipment dedicated to exhaust heat, and it also makes operation management easier.In addition, the overall efficiency can be increased to 75 cm, resulting in energy savings and low pollution. A considerable amount of the waste heat that was previously discarded can be used as a heat source for hot water supply, space heating, process use, etc., or used indirectly as a cold source for cooling and freezing tanks, increasing overall efficiency and reducing operating costs. Therefore, it is economically attractive even for small-scale power generation facilities.

The present invention enables miniaturization of absorption chillers, eliminates the need for control from the load circuit in the absorption chiller, simplifies the control mechanism, and makes the system self-balancing for stable operation in power generation equipment. A heat recovery system can be provided, which can have extremely great practical effects.

[Brief explanation of the drawing]

Figure 1 shows the heat balance in conventional power generation equipment. 2 to 5 are drawings relating to embodiments of the present invention,
Figure 2 is a heat balance diagram of the basic cycle, Figure 3 is a configuration diagram showing the overall system configuration, Figure 4 is a configuration diagram of the refrigeration set in the cold 1 water system, and Figure 5 is the power generation load, steam pressure, and absorption diagram. It is a graph showing the relationship between refrigerator load and vapor pressure. 1...Power generation equipment, 2...Heat recovery device,
3... Generator, 4... Prime mover, 5...
...Absorption refrigerator, 6...Compression refrigerator, T
...Heat exchanger, 12...Four generators, 13...
... Condenser, 14 ... Absorber, 15 ...
City pass, 16...Bypass valve.

Claims (1)

[Scope of Claims] 1. A heat recovery method for a power generation facility that covers the electricity demand including the power of a compression chiller, in which waste heat from the power generation facility is recovered and used as a heating source for a generator of an absorption chiller. , a power generation characterized in that the return cold heat medium from the cooling load is first guided to the absorption chiller and rained down, then guided to the compression chiller and moved, and then applied to the cooling load. Heat recovery method in equipment. 2. In a heat recovery method for power generation equipment that covers the electricity demand including the power of a compression chiller, waste heat from the power generation equipment is recovered and used as a heating source for the generator of the absorption chiller, and the cold heat returned from the cooling load is recovered. The medium is first led to the absorption refrigerator for cooling, then to the compression refrigerator for cooling, and then supplied to the cooling load, and furthermore, the waste heat from the power generation equipment is transferred to the heating load. A heat recovery method in a power generation facility, characterized by heating the thermal medium by exchanging heat with the thermal medium.