JPS58185912A - Motive power generator - Google Patents

Abstract

PURPOSE:To improve the heat efficiency of a motive power generator which utilizes solar heat or waste heat of a plant or so by determining a quantity of heat medium circulated which may produce a maximum energy efficiency, according to a difference between an optimum value of a temperature of heat medium at the inlet side of a heat source and a detected value of said temperature. CONSTITUTION:If an intense of solar radiation is increased when a plant is stopped and a temperature T2 of heat medium inside a heat collector 1 therefore becomes higher than a temperature T1 of a heat accumulation tank 3, said temperatures being detected by detectors 15 and 16, respectively, electric current is fed through a pump exciting coil 24 via a comparator 20b and other means to start pumps 4, 8a and 8b. A three-way valve controller 26 is also electrified to control three-way valves 11a and 11b for cutting off a bypass flow passage 30, hence generating power in a Rankine cycle 2. A computing circuit 27 receives outputs of detectors 13 and 14 with respect to a temperature Ta of open air and an intense Q of solar radiation, calculates an optimum value T0 of a temperature of heat medium at the inlet side of the heat collector, makes detection 19 on a difference DELTAT between the value T0 and said temperature T1, and sends a signal for producing a maximum energy efficiency to a revolution number controller 28 of the pump 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power generation device that generates power using solar heat, factory waste heat, or the like.

Conventional power generation devices that utilize solar heat, factory waste heat, etc.
It consists of a heat source, a heat storage tank, a heat medium circulation pump, a heat collection loop, and a Rankine cycle that converts the collected heat into power. The heat collection rate is independent of the amount of solar radiation when using solar heat, the heat source temperature when using waste heat), the thermal state of the outside world (air temperature or condensation temperature of Rankine cycle), and the temperature of the heating medium at the inlet of the heat source. Since the amount of heat medium circulation was set, there was a drawback that it was not possible to achieve the optimum operating conditions in response to an increase in the amount of heat input at the heat source. This will be explained using FIG. 1 which is an exergy efficiency diagram for the case where exergy is defined by equation (1).

However, Q: total amount of heat supplied from the high temperature heat source TA: high heat source temperature TB: low temperature heat source temperature Tc: high temperature heat source absolute temperature Also, exergy efficiency refers to the amount of heat the collector provides for the exergy included in the solar radiation on the heat collecting surface. It is the rate of exergi that can be collected.

In Figure 1, the vertical axis is the temperature of the heating medium at the inlet of the solar collector;
The horizontal axis is the heat medium circulation amount, the numerical value in the figure is the exergy efficiency, the solid line is the exergy efficiency contour line at a certain solar radiation amount and temperature, and the broken line is the heat medium temperature at the collector inlet side and the heat medium circulation amount that maximizes the exergy efficiency. Indicates the combination of

When the amount of solar radiation increases, the actual operating condition is at point A with respect to the optimum operating condition shown by the broken line. At this time, in conventional power generators, the amount of heating in the heat collection loop increases, and after some time delay, the operating conditions reach optimal point B, but during that time, they must be operated in a state with low exergy efficiency. . In other words, as the amount of solar radiation increases, the generated power increases only gradually.

This drawback also occurs when the heat source is other than solar heat, for example when waste heat is used as the heat source.

In this case, the same situation will hold if the total heat source temperature is substituted for the amount of solar radiation in FIG. 1.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks and to provide a power generation device that can immediately realize a line concentration condition that maximizes exergy efficiency in response to an increase in the amount of heat input in a heat source.

The present invention provides a detector that detects the thermal state of the heat source and the outside world, and the temperature of the heat medium at the inlet of the heat source, and detects the temperature of the heat medium at the inlet of the heat source in the heat collection loop based on the detection signals from each detector. The main feature is that the optimum value of is calculated, and the heat medium is flowed at a flow rate that maximizes the exergy efficiency based on the temperature difference between the calculation result and the detected value of the heat medium temperature on the heat source inlet side.

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 2 shows an embodiment in which the present invention is applied when the heat source is solar heat. The heat collection loop includes a heat collector 1, a steam generator 5 connected to the heat collector 1 via a three-way valve 11af, a heat storage tank 3 connected to the heat medium outlet side of the steam generator 5, and a heat storage tank 3 connected to the heat medium outlet side of the steam generator 5. A heat medium circulation pump 4 and a three-way valve 11b provided between the heat storage tank 3 and the heat medium inlet side of the heat collector 1, and a three-way valve 11a and ll.
and a bypass flow path 30 provided between the

On the other hand, the Rankine cycle 2 consists of a steam generator 5, an expansion mechanism 6, a condenser 7, and a pump 8a.
It is connected to the rear link tower 9 via a pump 8b', and the power generated in the expansion mechanism 6 is supplied to a load 10.

Figure 3 shows the control device for the power generator shown in Figure 2.
13 is a detector for temperature T1 as the thermal state of the external world; 14
17 is a detector for the amount of solar radiation Q, which is the thermal state of the heat source, and 17 is the outside temperature T, and from the amount of solar radiation Q, the optimal value To of the heating medium temperature on the inlet side of the heat collector 1 (in the flat part of the broken line in FIG. This is an arithmetic circuit that performs all calculations (temperature indicated). 15 is a detector for detecting the temperature T of the heat medium introduced into the heat collector 1 (in this embodiment, it is substantially equal to this and the entire temperature of the heat storage tank 3 is detected); 16 is a collector; Detector for internal heating medium temperature T2 of heating device 1, 1
8 is a circuit for setting the lower limit temperature TL of the heat storage tank 3.

Reference numeral 19 denotes the heat medium temperature T at the inlet of the collector detected by the detector 15 and the optimum value T calculated by the arithmetic circuit 17. This is a temperature difference detector that detects the temperature difference ΔT between the 2
0a is the lower limit temperature TL of the energy storage tank 3 set in the setting circuit 18 and the temperature T1 detected by the detector 15.
This is a comparator that compares the values of TI and TL, and outputs i ``1'' when TI>TL, and outputs ``0''' when this is not the case. 20b compares the temperatures T+ and T2 k detected by the rain detectors 15 and 16, and when the internal temperature T2 of the heat collector 1 is higher than the heat storage tank temperature T1, the output is "1".
This is a comparator that outputs 0 when it is not.

21a, the output of the comparator 20b is '1' (i.e. 'r2').
>'r, ), the output Δ of the temperature difference detector 19
T (=T, -'ro)k An AND circuit 28 passing through the voltage generation circuit 27 is a rotation speed control section of the heat medium circulation pump 4 connected to the voltage generation circuit 27.

22 is an OR circuit which inputs the outputs of the comparators 20a and 20b, and 24 is an excitation coil for starting the pumps 4, 8a, and 8b, which is excited when the output is '1''. An AND circuit 25 inputs the output of the comparator 20a and the output of the comparator 20b via the inverting circuit 23, and operates the driving device of the three-way valves 11a and 11b so that the heat medium flows through the bypass flow path 30. The AND circuit 21 is in an operating state in which power is generated by flowing the flow.
The rotation speed control section 2 only when the output of b is '1#.
This is a constant voltage generation circuit that applies a constant voltage to 8. Reference numeral 26 indicates an operating state in which the driving devices for the three-way valves 11a and 11b are activated to collect heat.

Next, the operation of this embodiment will be explained. While the device is stopped, when the amount of solar radiation increases and the heat medium temperature T2 in the heat collector 1 becomes higher than the heat storage tank temperature T, the output of the comparator 20b becomes 1#, and the The excitation coils 24 for starting the pumps 4.8a and 8b are energized to start them, and the three-way valves 11a and llb are operated in the direction of cutting off the bypass flow path 30'f, so that the heat medium is supplied to the pump 4, the three-way It circulates through the path of the valve 11b1 heat collector 1, the three-way valve 11a1 steam generator 5, and the heat storage tank 3, and the Rankine cycle 2
(26 operating states).

The amount of heat medium circulated at this time is determined as follows.

outside air temperature T detected by the detector 13;

and the amount of solar radiation Q detected by the detector 14, the calculation circuit 17 determines the optimum value To of the heat medium temperature at the inlet side of the collector.
The difference ΔT between the optimum value To and the temperature T1 of the heat storage tank 3 is detected by the temperature difference detector 19, and a signal corresponding to the temperature difference ΔT is sent to the voltage generating circuit 27 via the all-AND circuit 21a'.
A signal is sent to the rotation speed control section 28 of the pump 4 to control the circulation amount to maximize the exergy efficiency.

This circulation amount control is performed as follows. FIG. 4 shows the relationship between the input signal (ΔT) and the output voltage in the voltage generation circuit 27. In the region where ΔT is negative (i.e., T, (T.), the larger the difference, the more the rotation speed of the pump 4. Control part 2
Lower the voltage applied to 8, that is, lower the rotational speed, and
Let be less. To explain this with reference to Figure 1, T + <
In the case of 'I''o, that is, for example, when the operating conditions at point A are given, the amount of heat medium circulation is reduced until the operating conditions at point 0 are reached, and when T1≧To is reached, , the pump 4 is operated at a constant rotational speed to keep the circulation amount of the heat medium constant.By performing such control, when the amount of solar radiation increases, the temperature will rise above the dashed line shown as the optimum operating condition in Fig. 1. operating conditions can be immediately achieved.

On the other hand, the amount of solar radiation decreases, and the internal temperature T2 of the heat collector decreases
temperature T becomes lower (Tl > T2 ), and the heat storage tank temperature T1 is higher than the set lower limit temperature TL (Tl >
TL), the output of the comparator 20a is '1'' and the output of the comparator 20b is IOjl, so the AND circuit 21
The output of b becomes '1j', the three-way valves 11a and llb are switched, the heat medium is circulated through the bypass passage 30, and a state 25 is realized in which heat is not collected but power is generated. That is, the heat medium is transferred to the pump 4, the three-way valve 11b1, and the bypass channel 30.
, the three-way valve 11a1, the steam generator 5, and the heat storage tank 3. The amount of heat medium circulated by the pump 4 at this time is determined by the signal from the constant voltage generating circuit 29. Temperature T of heat storage tank 3,
When the temperature drops further and becomes lower than the set lower limit temperature TL, the output of the comparator 20a also becomes @0'', so the output of the OR circuit 22 also becomes lOjl, and the ports 4, 8a, and 8b stop.

According to this embodiment, when the amount of solar radiation is large, solar heat can be effectively converted into motive power even if the temperature of the heat medium at the collector inlet side is low. In addition, even after the solar radiation disappears, the heat stored in the heat storage tank 3 can be converted into power without losing it to the heat collector (9).

In addition, in the example, the case where the solar total heat source is used is shown, but when using the total heat source such as waste heat, the example can be applied by replacing #I source humidity temperature at the location corresponding to the amount of solar radiation. . Further, the amount of heat medium circulation can be controlled not only by controlling the pump rotation speed as in the embodiment, but also by providing a bypass valve in parallel with the heat medium circulation pump 4 and controlling the opening degree of the valve. . Furthermore, as a means of generating power,
In addition to the Rankine cycle, other power generating devices such as refrigerators, Platon cycles, Stirling cycles, etc. are also used.

As described above, in the present invention, a detector is provided to detect the heat source, the thermal state of the outside world, and the temperature of the heat medium on the heat source inlet side, and the heat source inlet side in the heat collection loop is determined based on the state of the heat source and the outside air temperature. Calculate the optimal value of the heating medium temperature,
By comparing the nuclear calculation results and the detected value of the heating medium temperature at the heat source inlet side, we decided to flow the heating medium circulation amount that maximizes the exergy efficiency based on the temperature difference between them. As a result, heat collection conditions with maximum exergy efficiency can be immediately achieved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the heat medium temperature at the collector inlet side and the amount of heat medium circulation in a solar heat collector, and the exergy efficiency.
FIG. 3 is a system diagram of an embodiment of the present invention, FIG. 3 is a control block diagram of the core embodiment, and FIG. 4 is a characteristic diagram of a voltage generating circuit used in the embodiment. 1... Heat collector, 2... Rankine cycle, 3...
- Heat storage tank, 4... Heat medium circulation pump, 11... Three-way valve, 13... Temperature detector, 14... Solar radiation amount detector, 1
5... Heat storage tank temperature detector, 17... Arithmetic circuit, 19
... Temperature difference detector, 24 ... Pump excitation coil, 25
．． 26... Three-way valve operation control section, 27... Voltage generation circuit, 28... Pump rotation speed control section, 29... Constant voltage generation circuit. C11) 1st (2) Ri J Sheb 1 If @ De 1 Town - Toyo Ni

Claims (1)

[Claims] A power generation device comprising a heat collecting loop equipped with a heat source and a heat medium circulation pump, and a means for converting the amount of heat collected in the riding loop into power, comprising: a detector for the thermal state of the heat source and the outside world; a calculation means for determining the optimum value of the heat medium temperature on the heat source inlet side based on the detection signal of the detector; a heat source inlet side heat medium temperature detector; a detected value of the heat source inlet side heat medium temperature by the detector and the optimum value; A power generating device characterized by comprising means for circulating a heat medium to a heat source such that the exergy efficiency is maximized due to the temperature difference between the heat source and the heat source.