JP2003227313A - Method of operating exhaust heat recovery power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a receiver tank used to recover energy from a heat source which shows a remarkable change in temperature. <P>SOLUTION: In Fig. (a), a required time when the flow rate of heat source fluid is switched from Q2 to Q3 is taken as T23. In Fig. (b), the opening/closing speed is adjusted so that the time t23 in which the flow rate of the working fluid is changed from q2 to q3 matches or almost matches T23. The imbalance of the flow rates of the heat source fluid and the working fluid that is likely to occur when switching the flow rate can be minimized to the degree without real damage. If the imbalance in the flow rates does not occur, a sudden change of the level in the receiver tank does not occur. As a result, the receiver tank can be downsized. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for effectively recovering energy from an exhaust heat source whose amount of heat fluctuates.

[0002]

2. Description of the Related Art Heat recovery technology for recovering heat energy from high-temperature exhaust gas is widely used. However, heat recovery from a low-temperature heat source having a temperature of less than 100 ° C. has hardly been carried out because it is difficult to recover the heat commensurate with equipment investment. A technique capable of effectively recovering heat from such a low temperature heat source of less than 100 ° C. is disclosed in, for example, JP-A-2000-1994.
It is the exhaust heat recovery cycle proposed in 08 publication "Power generation method and power generation equipment using high temperature waste water". This exhaust heat recovery cycle uses a water / ammonia mixed fluid as a heat medium, and it has become possible to effectively recover heat from wastewater at about 98 ° C, which was considered difficult in the past.

On the other hand, in the steelmaking process, pure oxygen is blown into the pig iron in the converter to change the carbon (C) in the pig iron to carbon monoxide (CO) to obtain steel. A large amount of heat (heat of oxidation) is generated along with the oxidation reaction at this time. A technique for recovering this large amount of heat is disclosed in, for example, JP-A-11-223417.
It is disclosed in Japanese Unexamined Patent Application Publication "Method for recovering low-temperature waste heat generated from steel manufacturing process".

The heat recovery technique by replacing the absorption refrigerator with the exhaust heat recovery cycle disclosed in Japanese Patent Laid-Open No. 11-223417 is well worth studying.

FIG. 9 is a principle diagram of a system in which a conventional converter exhaust gas duct is combined with an exhaust heat recovery cycle. 100
Is a converter, 101 is a converter exhaust gas duct covering the converter 100, this converter exhaust gas duct 101 is a water cooling duct for passing cooling water between the double walls, 102 is a cooling water inlet, 103 Is the cooling water outlet.

An exhaust heat recovery cycle 110 is surrounded by an imaginary line, and this frame 110 is transcribed by reference numeral 11 in FIG. 1 of Japanese Patent Laid-Open No. 2000-199408. However, the code was reassigned. The cycle 110 includes an evaporator 111 and a gas-liquid separator 11
2, a turbine 113, a generator 114, first and second heat exchangers 115 and 116, a receiver tank 117, and a circulation pump 118.

A heat source fluid supply pipe 104 is extended from the cooling water outlet 103, is connected to the evaporator 111, and a return pipe 105 is extended from the evaporator 111, and is connected to the cooling water inlet 102. Reference numeral 106 is a circulation pump. Water having a boiling point (100 ° C.) or less is circulated in the converter exhaust gas duct 101, the heat source fluid supply pipe 104, and the return pipe 105.

On the other hand, in cycle 110, a water / ammonia mixed fluid is circulated. When the temperature of the water-ammonia mixed fluid becomes high, the evaporation of ammonia becomes vigorous, the amount of ammonia vapor becomes large, and the amount of ammonia water becomes small. The opposite is true at low temperatures. Therefore, the water / ammonia mixed fluid that has received heat in the evaporator 111 is divided into ammonia vapor and ammonia water by the gas-liquid separator 112, and the ammonia vapor drives the turbine 113 to become a low temperature, and the second heat exchanger 116 is It goes to the receiver tank 117 via. On the other hand, the ammonia water goes directly to the receiver tank 117 without passing through the turbine 113 though passing through the heat exchangers 115 and 116. The water / ammonia mixed fluid accumulated in the receiver tank 117 returns to the evaporator 111 by the action of the circulation pump 118.

That is, the heat held by the heat source fluid is transferred (recovered) to the water / ammonia mixed fluid in the evaporator 111, and the resulting ammonia vapor is used to turn the turbine 113 to generate electrical energy by the generator 114 connected to the turbine 113. The heat can be recovered in the form of.

[0010]

By the way, the converter 100
In general, we carry out ordinary blowing which consists of charging, blowing, measurement, tapping, and slag. At this time, charging is about 3
Minutes, blowing for about 17 minutes, measurement for about 5 minutes, tapping for about 4 minutes, and waste for about 4 minutes for a total of 33 minutes. About 5 out of 33 minutes
In blowing that occupies 2% (17 minutes), a large amount of exhaust gas that is heated to a high temperature is generated due to the heat of oxidation caused by blowing oxygen. But,
In other charging, measurement, tapping, and slag, the amount of exhaust gas is zero or small, and the heat of exhaust gas is also small.

On the other hand, the flow rate of the heat source fluid (hot water) is set to an amount such that the temperature at the cooling water outlet 103 does not exceed the boiling point at the time of blowing, which is the most thermally severe, and the determined "flow rate" is basically unchanged. . As a result, the heat source fluid (hot water) flowing through the converter exhaust gas duct 101, the heat source fluid supply pipe 104, and the return pipe 105.
The "temperature" of fluctuates greatly.

When the temperature of the heat source fluid decreases, the evaporator 111
The amount of heat absorbed by the water / ammonia mixed fluid in the air decreases, and as a result, the amount of ammonia vapor decreases and the amount of ammonia water increases. Since the ammonia vapor is a low-density gas and the ammonia water is a high-density liquid, the weight of the water / ammonia mixed fluid stored in the evaporation pipe 119 in the evaporation pipe 119 becomes large.

Since the weight of the water / ammonia mixed fluid circulating in the cycle 110 is constant, as described above, the evaporation pipe 1
When the water / ammonia mixed fluid stored in 19 increases,
In return, the water / ammonia mixed fluid in the receiver tank 117 is reduced, and the liquid level in the receiver tank 117 is lowered. That is, when the temperature of the heat source fluid decreases, the liquid level in the receiver tank 117 decreases.

Similarly, when the temperature of the heat source fluid rises, the amount of heat absorbed by the water / ammonia mixed fluid in the evaporator 111 increases, resulting in an increase in ammonia vapor and a decrease in ammonia water.

Since the weight of the circulating water / ammonia mixed fluid is constant, when the amount of the water / ammonia mixed fluid stored in the evaporation pipe 119 decreases as described above, the water / ammonia mixed fluid in the receiver tank 117 is compensated for. Increasing, the liquid level in the receiver tank 117 rises.
That is, when the temperature of the heat source fluid rises, the liquid level in the receiver tank 117 rises.

As described above, conventionally, the receiver tank 117 having a size capable of sufficiently absorbing the rise / fall of the liquid level of the working fluid (water / ammonia mixed fluid) is required. That is, when the temperature of the heat source fluid changes like the converter exhaust gas duct 101, it was necessary to install a large receiver tank 117. Moreover, it is necessary to increase the tank capacity as the temperature change increases. Since the receiver tank 117 is a pressure vessel, it is an expensive device.
Increasing the size is not preferable because it prevents the cost of the equipment from being reduced and the equipment is made compact.

Therefore, an object of the present invention is to provide a technique capable of recovering energy from a heat source whose temperature changes remarkably without increasing the size of the receiver tank.

[0018]

In order to achieve the above object, a first aspect of the present invention is to temporarily store a heat source fluid in which exhaust heat is recovered from an exhaust heat source whose heat quantity fluctuates in a storage tank, and the heat source of the storage tank is stored. By supplying a predetermined amount of fluid to the evaporator and supplying a working fluid composed of a multi-component mixed medium such as a water / ammonia mixed fluid to the evaporator, the heat of the heat source fluid is transferred to the working fluid, and this working fluid In the exhaust heat recovery power generation system that turns the power generation turbine to recover exhaust heat in the form of electric energy, depending on the level of the heat source fluid accumulated in the storage tank,
It is characterized in that the flow rate of the heat source fluid and the working fluid is controlled.

Focusing on the level of the heat source fluid in the storage tank, if this level is low, the storage tank may become empty. To avoid this, the flow rate of the heat source fluid supplied to the evaporator is set to be low. On the contrary, if the level of the heat source fluid in the storage tank is sufficiently high, the flow rate of the heat source fluid supplied to the evaporator can be set high. Then, when the flow rate of the heat source fluid increases, the flow rate of the working fluid is increased,
When the flow rate of the heat source fluid decreases, the flow rate of the working fluid is decreased to keep the distribution of ammonia vapor and ammonia water constant.

If the distribution of ammonia vapor and ammonia water is constant, there is almost no level fluctuation that should be absorbed in the receiver tank, and as a result, the capacity of the receiver tank can be suppressed and the receiver tank can be made smaller. Can be easily achieved.

According to a second aspect of the present invention, the levels of the storage tank are divided into a plurality of levels, and the flow rates of the heat source fluid and the working fluid are controlled stepwise in accordance with these divisions.

It is desirable to continuously control the flow rates of the heat source fluid and the working fluid according to the level of the heat source fluid accumulated in the storage tank, but a high-grade and expensive control system capable of PID control or the like is required. . However, in claim 2, for example, the level of the storage tank is divided into three levels A, B, and C, and the level A
The flow rate of the heat source fluid and the working fluid is assigned to a in the case of, the flow rate is assigned to b in the case of level B, and the flow rate is assigned to c in the case of level C. As a result, the control system is simplified and the cost of the control unit can be reduced.

A third aspect of the present invention is characterized in that when the flow rates of the heat source fluid and the working fluid are controlled stepwise, the required change times of the heat source fluid and the working fluid are matched.

If the change in the flow rate of the working fluid does not follow the change in the flow rate of the heat source fluid, the distribution ratio between the ammonia vapor and the ammonia water changes significantly, and the small capacity receiver tank cannot absorb the change. Therefore, in claim 3, the distribution ratio of the ammonia vapor and the ammonia water is made constant by matching the required change times of the heat source fluid and the working fluid.

According to a fourth aspect of the present invention, the heat source fluid in which the waste heat is recovered from the exhaust heat source whose amount of heat fluctuates is temporarily stored in the storage tank, and the heat source fluid in the storage tank is supplied to the evaporator in a predetermined amount and the receiver tank By supplying a working fluid consisting of a multi-component mixed medium such as water / ammonia mixed fluid stored in the evaporator to the evaporator, the heat of the heat source fluid is transferred to the working fluid, and the working fluid rotates the power generation turbine to generate electricity. In an exhaust heat recovery power generation system that recovers exhaust heat in the form of energy, when increasing the flow rates of the heat source fluid and the working fluid, first increase the flow rate of the heat source fluid and increase the flow rate of the working fluid based on this increase completion information. When performing the series control to reduce the flow rate of the heat source fluid and the working fluid, first reduce the flow rate of the working fluid, and based on this reduction completion information, change the flow rate of the heat source fluid. And performing series control so little of.

The series control here means that one control is performed and then another control is sequentially performed, such that the control is sequentially performed. If the working fluid is left as it is and the flow rate of the heat source fluid is increased, the temperature of the working fluid rises,
The proportion of ammonia vapor in the working fluid increases, and the weight of the working fluid that can be stored in the evaporation pipe in the evaporator decreases. As a result, the liquid level in the receiver tank rises. Next, the flow rate of the working fluid is increased based on the increase completion information of the flow rate of the heat source fluid. As the working fluid increases, the rise in temperature of the working fluid peaks or falls, and consequently the rise in the liquid level in the receiver tank also peaks or falls.

That is, when the flow rates of the heat source fluid and the working fluid are increased, first, the flow rate of the heat source fluid is increased, and the series control is performed to increase the flow rate of the working fluid based on the increase completion information. It is possible to go up, and the degree of uphill can be suppressed lightly.

Further, when reducing the flow rates of the heat source fluid and the working fluid, first, the flow rate of the working fluid is reduced, and series control is performed to reduce the flow rate of the heat source fluid based on the reduction completion information. That is, if the heat source fluid is left as it is and the flow rate of the working fluid is reduced, the temperature of the working fluid rises, the proportion of ammonia vapor in the working fluid increases, and the working fluid that can be stored in the evaporation pipe in the evaporator is increased. Weight is reduced. As a result, the liquid level in the receiver tank rises. Next, when the flow rate of the heat source fluid is decreased, the temperature rise of the working fluid reaches a peak or a drop, and as a result, the rise in the liquid level in the receiver tank also peaks or drops. .

As described above, when the flow rates of the heat source fluid and the working fluid are reduced, first, the flow rate of the working fluid is reduced, and the series control for reducing the flow rate of the heat source fluid is performed based on the reduction completion information. The level can be increased, and this increase can be suppressed to a low level.

As described above, according to the fourth aspect, it is only necessary to consider the rise of the completed liquid level without considering the decrease of the liquid level, and the degree of this increase is slight. The tank can be significantly downsized.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of the reference numerals. FIG. 1 is a principle diagram of an exhaust heat recovery power generation system according to the present invention, and the basis of the principle is the same as that described in the related art. That is, 10 is a converter, 11 is a converter exhaust gas duct covering the converter 10, this converter exhaust gas duct 11 is a water cooling duct for passing cooling water between double walls, and 12 is cooling water. An inlet 13 is a cooling water outlet.

20 is an exhaust heat recovery cycle surrounded by an imaginary line. The cycle 20 includes an evaporator 21, a gas-liquid separator 22, a turbine 23, a generator 24, a first and second heat exchanger 25,
26, a receiver tank 27, a working fluid circulation path 29, a circulation pump 31 provided in the circulation path 29, and a flow control valve 3
2 and a flow meter 33. Reference numeral 34 is an evaporation pipe in the evaporator 21, and 35 is a control unit.

A heat source fluid supply pipe 41 is extended from the cooling water outlet 13 and connected to the evaporator 21, and a storage tank 42 for temporarily storing the heat source fluid in the heat source fluid supply pipe 41 and this storage tank 42. A circulation pump 43 for pressure-feeding the heat source fluid, a flow rate control valve 44 for controlling the flow rate of the heat source fluid, and a flow meter 45 for measuring the flow rate are provided. 46
Is a level meter attached to the storage tank 42.
Thus, the level of the heat source fluid temporarily stored in the storage tank 42 can be measured.

A return pipe 47 is extended from the evaporator 21, is connected to the cooling water inlet 12, and an auxiliary storage tank 48 and an auxiliary pump 49 are provided in the return pipe 47. Further, 51 is an overflow pipe, and the storage tank 42
When the water overflows, the heat source fluid overflowing in the overflow pipe 51 is directly released to the auxiliary storage tank 48. With the above configuration, water having a boiling point (100 ° C.) or lower is circulated through the converter exhaust gas duct 11, the heat source fluid supply pipe 41, and the return pipe 47.

On the other hand, in the cycle 20 in the frame, a water / ammonia mixed fluid as a working fluid is circulated. When the temperature of the water-ammonia mixed fluid becomes high, the evaporation of ammonia becomes vigorous, the amount of ammonia vapor becomes large, and the amount of ammonia water becomes small. The opposite is true at low temperatures. Therefore, the water / ammonia mixed fluid that has received heat in the evaporator 21 is divided into ammonia vapor and ammonia water by the gas-liquid separator 22, and the ammonia vapor drives the turbine 23 to become a low temperature, and the second heat exchanger 26
Head to the receiver tank 27 via. On the other hand, the ammonia water passes through the heat exchangers 25 and 26, but the turbine 2
It goes directly to the receiver tank 27 without going through 3. The water / ammonia mixed fluid accumulated in the receiver tank 27 returns to the evaporator 21 by the action of the circulation pump 31.

That is, the evaporator 21 transfers (recovers) the heat of the heat source fluid to the water / ammonia mixed fluid, and the resulting ammonia vapor rotates the turbine 23, and the electric power generated by the generator 24 connected to the turbine 23 is changed. The heat can be recovered in the form of.

However, the converter 10 is generally charged → blown →
Normal blowing, which consists of the steps of measurement, tapping, and slag, is performed, and the amount and temperature of exhaust gas generated changes drastically in each step. In order to perform appropriate cooling management of the converter exhaust gas duct 11, it is desirable to change the flow rate of the heat source fluid in response to changes in the amount and temperature of exhaust gas. In addition, it is also desirable to change the working fluid flow rate in response to changes in the heat source fluid flow rate. Therefore, in the present invention, the following operating method is implemented.

The first invention of the driving method will be described with reference to FIGS. FIG. 2 is a flow chart of the method for operating the exhaust heat recovery power generation system (first invention), where STXX indicates a step number. ST01: First, the liquid level in the storage tank 42 is detected by the level meter 46 shown in FIG.

ST02: The control unit 35 determines the flow rate set value of the heat source fluid and the flow rate set value of the working fluid from the read level and the maps 1 and 2 (described in FIGS. 3 and 4) stored in advance. .

FIG. 3 is a map diagram for the operating method (first invention) of the exhaust heat recovery power generation system, where the horizontal axis represents the level of the storage tank, and the vertical axis represents the flow rate set value of the heat source fluid and the flow rate of the working fluid. Indicates the set value. If the value read by the control unit 35 is L1 on the horizontal axis scale, a vertical line is extended as indicated by the arrow, and a horizontal line is extended as indicated by the arrow from the point where the curve intersects with the Q on the vertical axis.
Read 1, q1. With this, the heat source fluid flow rate set value G1 and the working fluid flow rate set value g1 for the level L1 can be determined.

Returning to FIG. ST03: The flow rate of the heat source fluid is controlled by the control unit 35, the flow meter 45 and the flow rate control valve 44 of FIG. 1 so that the flow rate set value G1 is set. Similarly, the control unit 35, the flow meter 33, and the flow control valve 32 are controlled so that the set flow rate setting value g1 is achieved.
Controls the flow rate of the working fluid.

By increasing the flow rate of the working fluid when the flow rate of the heat source fluid increases and decreasing the flow rate of the working fluid when the flow rate of the heat source fluid decreases, the distribution ratio of ammonia vapor and ammonia water is made constant. Can be kept.

If the distribution of the ammonia vapor and the ammonia water is constant or almost constant, the level fluctuation to be absorbed in the receiver tank hardly occurs, and as a result, the capacity of the receiver tank can be suppressed and the receiver tank capacity can be suppressed. Miniaturization can be easily achieved.

FIG. 4 is another map diagram for the operating method (first invention) of the exhaust heat recovery power generation system.
It can be said that it is a simple type map. That is, the storage tank level on the horizontal axis is divided into a plurality of (A, B, C in the figure), and the heat source fluid flow rate set value and the working fluid flow rate set value a, b,
Allocate c in steps. If the level read by the control unit is L2 on the horizontal scale, use the arrow and
Heat source fluid flow rate setting value G2 and working fluid flow rate setting value g
2 can be set. Similarly, if the level read next by the control unit is L3 on the scale of the horizontal axis, the flow rate set value G3 of the heat source fluid and the flow rate set value g3 of the working fluid can be determined.

As shown in FIG. 3, it is desirable to continuously control the flow rates of the heat source fluid and the working fluid in accordance with the level of the heat source fluid accumulated in the storage tank, but it is possible to perform high-quality and expensive control such as PID control. The system becomes indispensable. In this regard, in FIG. 4, for example, the level of the storage tank is divided into three levels A, B, and C, the flow rate of the heat source fluid and the working fluid is a at the level A, and the flow rate is b at the level B. When the level is C, the flow rate is assigned to c. As a result, the control system is simplified and the cost of the control unit can be reduced. The number of divisions is arbitrary.

When the flow rate of the heat source flow rate is switched from G2 to G3 and the flow rate of the working fluid is switched from g2 to g3, it is not preferable that the switching timings are deviated from each other. Therefore, when using the map of FIG. 4, it is desirable to perform the synchronization control described below.

FIG. 5 is a flow rate curve diagram connected to FIG. 4. The vertical axis of (a) shows the flow rate of the heat source fluid, the vertical axis of (b) shows the flow rate of the working fluid, and the horizontal axis shows time. . In (a), when the change required time for switching the flow rate of the heat source fluid from Q2 to Q3 is T23, this time T23 is determined from the opening / closing speed and the opening or closing angle of the flow rate control valve 44 in FIG.

In (b), the control unit 35 (see FIG. 1)
When the flow control valve 32 is opened or closed, the time t2 until the flow rate of the working fluid changes from q2 to q3.
The opening / closing speed is adjusted so that 3 is matched or almost matched with the time T23. As a result, it is possible to reduce the flow rate imbalance between the heat source fluid and the working fluid, which is likely to occur at the time of switching the flow rate, to the extent that there is no actual harm. If there is no flow rate imbalance, there will be no sudden change in the level in the receiver tank 26.

In the latter half of the time axes of (a) and (b), the required change time T34 when the flow rate of the heat source fluid is changed from Q3 to Q4 and the required change time when the flow rate of the working fluid is changed from q3 to q4. It indicates that t34 was matched or almost matched.

Next, the second invention of the operating method will be described with reference to FIGS.
First, in FIG. 1, the heat source fluid having the flow rate Q circulates in the order of the converter exhaust gas duct 11, the storage tank 42, the evaporator 21, and the auxiliary storage tank 48, and the working fluid having the flow rate q circulates in the cycle 20 in FIG. I was doing. The operation mode of the converter 10 at that time is based on the accumulation of past data, the capacity and performance of the converter 10, the weight of pig iron to be charged therein, the temperature, etc. Can be well predicted.

Based on this prediction, the computer issues an instruction for changing the flow rate Q of the heat source fluid to the control section 35 as appropriate. For example, when blowing starts, the amount of exhaust gas increases rapidly. Therefore,
If a program for increasing the flow rate Q of the heat source fluid is installed in the computer before the start of blowing, a control unit 3 issues a change instruction (change instruction signal) for the flow rate Q of the heat source fluid.
You can call 5.

FIG. 6 is a flow chart of the method for operating the exhaust heat recovery power generation system (second invention), where STXX indicates a step number. ST10: Check whether there is an instruction to change the flow rate Q of the heat source fluid. When there is a change instruction, the process proceeds to ST11. ST11: It is assumed that the change instruction includes the correction value ΔQ for the current flow rate Q. Here, the correction value Δq of the flow rate q of the working fluid corresponding to the correction value ΔQ is determined. This correction value Δ
For q, for example, a map having ΔQ on the horizontal axis and Δq on the vertical axis is prepared, and Δq can be determined by this map.

ST12: Check whether the correction value ΔQ is positive. Positive increases flow rate. Negative means reducing the flow rate. If ST10 is Yes, ΔQ is 0.
Not (zero). ST13: If YES in ST12, the flow rate of the heat source fluid is changed from Q to (Q + ΔQ). This change is implemented by the control unit 35, the flow meter 45 and the flow control valve 44 of FIG.

ST14: When it is confirmed by the flow meter 45 of FIG. 1 that the increase in the flow rate of the heat source fluid is completed, the process proceeds to ST15. ST15: Change the flow rate of the working fluid from q to (q + Δq). This change is implemented by the control unit 35, the flow meter 33 and the flow control valve 32 of FIG.

FIG. 7 is a supplementary explanatory diagram of FIG. 6, and the above-mentioned S
To explain T13 to ST15 in a graph, in the flow chart of the heat source fluid in (a), the flow rate of the heat source fluid changes from Q toward (Q + ΔQ) at the point P1 at which the flow rate change instruction (here, the flow rate increase instruction) is received. increase. At the time point P2 when this increase is completed, increase completion information (increase completion signal) is issued. In the flow chart of the working fluid in (b), the working fluid is increased from q to (q + Δq) at the point P2 when the increase completion signal is received.

(C) is a graph showing the level of the receiver tank, and the liquid level starts to rise from the point P1.
This is because only the heat source fluid is increased and the temperature of the working fluid rises, which raises the level. The rise is slow due to the time delay. At point P2, the working fluid begins to increase, and the flow rate imbalance between the heat source fluid and the working fluid tends to be eliminated. Therefore, the rise of the liquid level stops and starts to fall. Therefore, it is understood that when the control of ST13 to ST15 is carried out, the liquid level in the receiver tank rises, and this amount of rise ΔL1 is relatively small.

Returning to FIG. ST16: If No in ST12, the flow rate of the working fluid is changed from q to (q + Δq). This change is implemented by the control unit 35, the flow meter 33 and the flow control valve 32 of FIG. Since Δq is negative, the flow rate of the working fluid decreases. ST17: After confirming that the flow rate of the working fluid has been reduced by the flow meter 33 of FIG. 1, the process proceeds to ST15. ST18: Change the flow rate of the heat source fluid from Q to (Q + ΔQ). This change is implemented by the control unit 35, the flow meter 45 and the flow control valve 44 of FIG. Since ΔQ is negative,
The heat source fluid flow rate is reduced.

FIG. 8 is another supplementary explanatory view of FIG. 6, and when the above-mentioned ST16 to ST18 are supplementarily explained in the graph, first, in the flow chart of the working fluid in FIG. The working fluid is reduced from q to (q + Δq) at the point P3 when the signal is received. At the point P4 when this reduction is completed, reduction completion information (reduction completion signal) is issued. In the flow chart of the heat source fluid in (a), the flow rate of the heat source fluid is reduced from Q to (Q + ΔQ) at point P4 when the reduction completion signal is received.

(C) is a graph showing the level of the receiver tank, and the liquid level starts to rise from point P3.
This is because the temperature of the working fluid increases due to the decrease of the working fluid alone, which causes the level to rise. The rise is slow due to the time delay. At point P4, the heat source fluid begins to decrease, and the flow rate imbalance between the heat source fluid and the working fluid tends to be eliminated. Therefore, the rise of the liquid level stops and starts to fall. Therefore, it is understood that when the control of ST16 to ST18 is carried out, the liquid level in the receiver tank rises, and this rise amount ΔL2 is relatively small.

As is apparent from FIGS. 7 (c) and 8 (c) described above, it is not necessary to consider the decrease of the liquid level and it is sufficient to consider only the increase of the liquid level, and the extent of this increase. Since it is mild, the receiver tank 2 of FIG.
It is possible to significantly reduce the size of 6.

The first and second inventions of the operating method may be carried out independently of each other, or may be carried out by combining the first invention and the second invention. Absent.

Further, the operating method of the exhaust heat recovery power generation system of the present invention has been explained by applying the converter as a converter, but the applying object is arbitrary as long as it is an exhaust heat source whose heat quantity fluctuates, and it is particularly limited to the converter. Not something to do.

[0063]

The present invention has the following effects due to the above configuration. According to a first aspect of the present invention, in the exhaust heat recovery power generation system, the flow rate control of the heat source fluid and the working fluid is performed according to the level of the heat source fluid stored in the storage tank, and the operation is performed when the flow rate of the heat source fluid increases. By increasing the flow rate of the fluid and decreasing the flow rate of the working fluid when the flow rate of the heat source fluid decreases, the distribution of the working fluid vapor and the working fluid liquid can be kept constant, and the distribution of the vapor and the liquid can be maintained. Is constant, the level fluctuation that should be absorbed by the receiver tank hardly occurs, and as a result, the capacity of the receiver tank can be suppressed and the miniaturization of the receiver tank can be easily achieved.

In the second aspect, for example, the level of the storage tank is divided into three levels A, B, and C, the flow rate of the heat source fluid and the working fluid is a when the level is A, and the flow rate is b when the level is B. Similarly, at the level C, the flow rate is assigned to c. As a result, the control system is simplified and the cost of the control unit can be reduced.

A third aspect of the present invention is characterized in that when the flow rates of the heat source fluid and the working fluid are controlled stepwise, the required change times of the heat source fluid and the working fluid are matched. If the change in the flow rate of the working fluid does not follow the change in the flow rate of the heat source fluid, the distribution of ammonia vapor and ammonia water fluctuates, and the fluctuation cannot be absorbed by the small-capacity receiver tank. Therefore, in claim 3, the heat source fluid and the working fluid are changed in the required time so that the distribution of the ammonia vapor and the ammonia water is kept constant.

According to the fourth aspect, when the flow rates of the heat source fluid and the working fluid are increased, the flow rate of the heat source fluid is first increased, and the series control is performed to increase the flow rate of the working fluid based on the increase completion information. As a result, the level of the receiver tank rises, and this degree of rise can be suppressed to a low level. According to the fourth aspect, when reducing the flow rates of the heat source fluid and the working fluid, first, the flow rate of the working fluid is reduced, and the series control is performed to reduce the flow rate of the heat source fluid based on the reduction completion information. As a result, the level of the receiver tank rises, and this degree of rise can be suppressed to a low level.

As described above, according to claim 4, since it is only necessary to consider the rise of the completed liquid level without considering the fall of the liquid level, and the degree of this rise is slight, the receiver The tank can be significantly downsized.

[Brief description of drawings]

FIG. 1 is a principle diagram of an exhaust heat recovery power generation system according to the present invention.

FIG. 2 is a flow chart of an operating method (first invention) of the exhaust heat recovery power generation system.

FIG. 3 is a map diagram for a method of operating an exhaust heat recovery power generation system (first invention).

FIG. 4 is another map diagram for the operating method (first invention) of the exhaust heat recovery power generation system.

FIG. 5 is a flow rate curve diagram connected to FIG.

FIG. 6 is a flow chart of a method for operating an exhaust heat recovery power generation system (second invention).

7 is a supplementary explanatory diagram of FIG.

FIG. 8 is another supplementary explanatory diagram of FIG.

FIG. 9: Principle diagram of a system that combines a conventional converter exhaust gas duct with an exhaust heat recovery cycle

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Converter as an exhaust heat source whose heat quantity fluctuates, 21 ... Evaporator, 23 ... Turbine, 24 ... Generator, 32,44 ... Flow control valve, 33, 45 ... Flow meter, 34 ... Evaporation pipe in evaporator , 35 ... control unit, 42 ... storage tank, 46 ... level meter.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masato Sakakibara             Sumitomo Metal Industries, No. 3, Hikari, Oshima, Kashima City, Ibaraki Prefecture             Kashima Steel Works Co., Ltd. (72) Ikuma Sato, Inventor             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION F-term (reference) 3G081 BA02 BB03 BB05 BC13 BD00                       DA04 DA14                 5H590 AA02 CA08 CE01 EA16 EA18                       FA05 GA10 HA15 HA18 HA25

Claims (4)

[Claims] 1. A heat source fluid in which exhaust heat is recovered from an exhaust heat source whose amount of heat fluctuates is temporarily stored in a storage tank, and a predetermined amount of the heat source fluid in this storage tank is supplied to an evaporator. By supplying a working fluid composed of a multi-component mixed medium such as, for example, to the evaporator, the heat retained by the heat source fluid is transferred to the working fluid, and the working fluid rotates the power generation turbine to discharge waste heat in the form of electric energy. In the exhaust heat recovery power generation system for recovering, the flow rate control of the heat source fluid and the working fluid is carried out according to the level of the heat source fluid accumulated in the storage tank. 2. The exhaust heat recovery power generation system according to claim 1, wherein the level of the storage tank is divided into a plurality of levels, and the flow rates of the heat source fluid and the working fluid are controlled stepwise according to these divisions. Driving method. 3. The operation of the exhaust heat recovery power generation system according to claim 2, wherein when the flow rates of the heat source fluid and the working fluid are controlled stepwise, the required change times of the heat source fluid and the working fluid are matched. Method. 4. A heat source fluid in which exhaust heat is recovered from an exhaust heat source whose amount of heat fluctuates is temporarily stored in a storage tank, and a predetermined amount of this heat source fluid is supplied to an evaporator and stored in a receiver tank. By supplying a working fluid composed of a multi-component mixed medium such as a water / ammonia mixed fluid to the evaporator,
In the exhaust heat recovery power generation system that transfers the retained heat of the heat source fluid to the working fluid, rotates the power generation turbine with this working fluid, and recovers the exhaust heat in the form of electric energy, when increasing the flow rate of the heat source fluid and the working fluid. ,
First, increase the flow rate of the heat source fluid, perform series control to increase the flow rate of the working fluid based on this increase completion information, and when decreasing the flow rates of the heat source fluid and the working fluid,
First, a method of operating an exhaust heat recovery power generation system, characterized in that a series control is performed in which a flow rate of a working fluid is reduced and a flow rate of a heat source fluid is reduced based on the reduction completion information.