JPH0823407B2 - Water supply control device for once-through type exhaust heat boiler - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply control of a boiler which obtains steam or hot water by utilizing exhaust heat of an internal combustion engine or an incinerator, and particularly to a water supply control device in a once-through type exhaust heat boiler. It is about.

[0002]

2. Description of the Related Art Generally, a once-through type boiler is designed so that its water level up to the middle of a heat receiving water pipe satisfies a circulating water flow rate ratio of 1/2 or less, and a thermosiphon is constructed with a rated heat load. It is supposed to be done. However, when the heat load decreases, the thermosyphon is not configured, and as a result, overheating occurs in the upper part of the heat receiving water pipe, causing damage to the heat receiving water pipe, and concentrating can water in the heat receiving water pipe. As a result, impurities are deposited, which also causes damage to the heat receiving water pipe.

Conventionally, in order to prevent damage due to overheating of the heat receiving water pipe in this type of boiler, proper control of water supply into the heat receiving water pipe has been performed.

However, the conventional water supply control is on / off control or proportional control for the required water level, and the above problems have not been solved yet. Also,
Some have adopted a means to raise the water level by controlling by two continuous water levels, but this control can detect the water level of only part of the heat receiving water pipes, so it is possible to cover the entire heat receiving water pipes. Therefore, it is difficult to prevent the heat receiving water pipe from overheating. Then, in the water level control by the double water level, it was also difficult to detect the representative value of the entire heat receiving water pipe by the position of the detection sensor. In addition, in the conventional proportional water supply control,
Displacer type, differential pressure transmitting type, etc. are used as sensors for water supply proportional control to optimize the amount of water supply per unit time, but these are both expensive, and this type of boiler is also used. There was a limit to its application.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention is such that the heat load of the exhaust heat boiler is [the temperature difference of the exhaust gas] × [the pressure loss of the exhaust gas] at the inlet and outlet of the exhaust heat boiler.
^It is based on the knowledge that it is almost proportional to ^1/2 , and based on this heat load, the water level of the heat receiving water pipe is changed to control to the optimum water level, and the water supply amount per unit time at this appropriate water level. By properly controlling the heat receiving water pipe, damage due to overheating of the heat receiving water pipe can be reliably prevented, and precipitation of impurities due to concentration of can water that causes damage to the heat receiving water pipe can be prevented. . Further, the water supply control is made possible by a pseudo proportional control system which can be provided at a low cost with a simple structure.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which a large number of heat receiving water pipes are housed and arranged, and an exhaust gas inlet line is connected to one side and the other side is connected to the other side. The exhaust gas outlet line is connected, and the temperature difference of the exhaust gas at the inlet and outlet of the once-through type exhaust heat boiler connected to the water supply line for supplying water to the heat receiving water pipe is detected, and the pressure loss value of the exhaust gas in the exhaust heat boiler is detected. , Calculate the temperature difference and pressure loss value detected to determine the heat load of the exhaust heat boiler, determine the appropriate value of the water level for the heat receiving water pipe under the obtained heat load, and determine the appropriate value And the actual water level of the heat receiving water pipe is compared, and in the water supply control device in the once-through type exhaust heat boiler configured to control the water supply level of the heat receiving water pipe based on this comparison result, A water level control cylinder for detecting the water level of the hot water pipe is provided, and detection ends for detecting water levels at a plurality of points in the water level control cylinder are respectively inserted and installed in the water level control cylinder, and a detection signal from each detection end is provided. Based on the rise time and the fall time of the water level between the detection ends, respectively, based on the rise time and the fall time,
A controller is provided which determines the water supply amount per unit time at the time of the next rise of the water level in the can and the lowering of the water level in the can, and which is provided with a controller for outputting the determined water supply amount as a control signal. Is controlled to control the number of rotations of the water supply pump provided in the water supply line.

[0007]

According to the water supply control device of the present invention, each detection end inserted and installed in the water level control cylinder outputs each detection signal to the controller. The controller receiving each detection signal measures the rising time and the falling time of the water level between the respective detection ends, and in order to make each of the measured times as long as possible, the water supply amount per unit time To decide.
The amount of water supply is determined as the amount of water supply at an appropriate water level determined based on the heat load of the exhaust heat boiler, and this is output as a control signal to the water supply pump provided in the water supply line. The water supply pump that has received this control signal continuously changes the number of revolutions and supplies the amount of water supply per unit time instructed by the controller into the heat receiving water pipe. As a result, the amount of water supply when the water supply valve is on is adjusted, and the on / off operation interval of the water supply valve is lengthened,
The control is similar to that of proportional water supply.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. The embodiment shown in the drawings illustrates, as an example, an exhaust heat boiler in which steam is obtained by utilizing exhaust heat from an internal combustion engine, an incinerator, or the like.
FIG. 3 is an explanatory view schematically showing an embodiment of a water supply control device.

First, an outline of an exhaust heat boiler 1 equipped with a water supply control device will be described with reference to FIG. 1. The exhaust heat boiler 1 supplies exhaust gas from an exhaust gas source (not shown) such as an internal combustion engine or an incinerator. It is configured to be introduced from the inlet line 2 on the one side thereof, heat-exchange with a large number of heat receiving water pipes 3 accommodated therein and generate steam, and exhaust gas from the outlet line 4 on the other side. .

The waste heat boiler 1 has a heat receiving water pipe 3 therein.
A water supply line 5 for supplying water to the inside is connected and connected. The water supply line 5 is provided with a water supply device (not shown) including a check valve, a filter, a chemical injection device, etc., and by operating the water supply pump P, water of an appropriate water source is filtered,
It becomes the chemical can water injected with the chemical liquid and is supplied into the heat receiving water pipe 3 of the exhaust heat boiler 1. A water supply valve 6 is provided downstream of the water supply pump P in the water supply line 5 to control ON / OFF of the water supply into the heat receiving water pipe 3.

The exhaust heat boiler 1 is connected to a take-out line 7 for taking out steam generated by heat exchange between the heat-receiving water pipe group 3 and the exhaust gas. The take-out line 7 is provided with a vapor valve 8 for taking out and using the vapor. Although detailed description is omitted, the extraction line 7 includes
In order to take out good quality steam, an appropriate steam separator (separator) is provided.

The exhaust heat boiler 1 is provided with a pressure detector 9 for detecting the internal pressure of the can. This pressure detector 9 detects the pressure inside the can of the exhaust heat boiler 1 which changes according to the fluctuation of the heat load during the operation of the exhaust heat boiler 1. When the pressure exceeds a set pressure value, an alarm is appropriately generated.

The heat receiving water pipe 3 of the exhaust heat boiler 1 is provided with a water level detecting end 10 for detecting the actual water level in the heat receiving water pipe 3. The water level detection end 10 detects the actual water level in the heat receiving water pipe 3 that changes according to the fluctuation of the heat load during the operation of the exhaust heat boiler 1. The water level control uses the detected water level as a detection signal. Output to the container 11.

The inlet line 2 of the exhaust heat boiler 1 is provided with an inlet temperature detector 12 for detecting the temperature of the exhaust gas introduced from the exhaust gas generation source into the exhaust heat boiler 1. The inlet temperature detector 12 detects the temperature of the exhaust gas introduced into the exhaust heat boiler 1 in the inlet line 2 and outputs the detected temperature as a detection signal to the inlet temperature measuring device 13. Further, the outlet line 4 of the exhaust heat boiler 1 is provided with an outlet temperature detector 14 for detecting the temperature of the exhaust gas discharged from the exhaust heat boiler 1. This outlet temperature detector 14
Detects the temperature of the exhaust gas in the outlet line 4 and outputs the detected temperature to the outlet temperature measuring device 15 as a detection signal.

A damper 17 for detecting the flow rate of the exhaust gas passing through the exhaust heat boiler 1 is provided in the bypass line 16 which constitutes a path connected to connect the inlet line 2 and the outlet line 4. It is provided. The damper 17 is configured to detect the flow rate of the exhaust gas passing through the exhaust heat boiler 1 based on the opening degree of the bypass line 16, and thus the opening degree of the damper 17, and the opening degree is used as a detection signal to detect the exhaust gas amount. Output to the measuring instrument 18. The exhaust gas amount measuring device 18 measures the amount of exhaust gas passing through the exhaust heat boiler 1 based on the opening signal from the damper 17,
The measured amount is output to the pressure calculator 19 as a detection signal. The pressure calculator 19 calculates the measurement amount from the exhaust gas amount measuring device 18 and calculates the pressure loss value of the exhaust gas in the exhaust heat boiler 1. That is, the damper 17, the exhaust gas amount measuring device 18, and the pressure calculator 19 constitute pressure detecting means for measuring the pressure loss value of the exhaust gas in the exhaust heat boiler 1. The pressure detecting means for measuring the pressure loss value is not limited to the above-described embodiment, and depending on the implementation, for example, without forming the bypass line 16, the same damper as the damper 17 is provided in the outlet line 4. (Not shown) is provided and the opening signal from this damper is sent to the pressure calculator 1.
A configuration for directly outputting to 9 is also suitable.

Further, the water supply control device according to the present invention is
The temperature difference of the exhaust gas at the inlet and outlet of the exhaust heat boiler 1 is detected, the pressure loss value of the exhaust gas passing through the exhaust heat boiler 1 is detected, and the heat load of the exhaust heat boiler 1 is detected from the temperature difference and the pressure loss value of the exhaust gas. Is determined and the water level of the heat receiving water pipe 3 is controlled according to the heat load. Therefore, in the present invention, the temperature difference of the exhaust gas at the inlet and outlet of the exhaust heat boiler 1 and the inside of the exhaust heat boiler 1 are determined. An arithmetic processing unit 20 for arithmetically processing the pressure loss value of the exhaust gas passing through is provided. The arithmetic processor 20 receives the exhaust gas temperature in the inlet line 2 as a detection signal from the inlet temperature measuring device 13 via the inlet temperature detector 12, and
The exhaust gas temperature in the outlet line 4 is measured by the outlet temperature detector 14
The pressure loss value of the exhaust gas which is received as a detection signal from the outlet temperature measuring device 15 through the exhaust gas and has passed through the exhaust heat boiler 1 from the pressure detecting means such as the damper 17, the exhaust gas amount measuring device 18, and the pressure calculator 19. Is received as a detection signal of The arithmetic processing unit 20 that receives these detection signals first performs arithmetic processing on the detection signals from both the temperature measuring devices 13 and 15 to detect the temperature difference of the exhaust gas. Next, the temperature difference and the pressure loss value are arithmetically processed to determine the heat load,
An appropriate value of the water level of the heat receiving water pipe 3 according to the heat load is determined. Then, the determined appropriate value of the water level is output to the water level controller 11 as a control signal.

Then, the water level controller 11 which receives the control signal of the proper water level level for the heat receiving water pipe 3 from the arithmetic processing unit 20 detects the control signal and the actual water level level from the water level detecting end 10 of the heat receiving water pipe 3. Compared with the detection signal of
An opening / closing control signal for controlling opening / closing of the water supply valve 6 provided in the water supply line 5 is output based on the comparison result. Thereby, the water supply to the heat receiving water pipe 3 is controlled, and the water level of the heat receiving water pipe 3 is appropriately maintained.

Next, regarding the water supply control device according to the present invention which is organically connected to the water supply control device, that is, the structure for appropriately controlling the water supply amount per unit time,
This will be described with reference to FIGS. 2 and 3. In FIG. 2, as a specific example of the water level detecting end 10, a water level control tube 23 is provided, which is connected to the heat receiving water pipe 3, the steam part connecting pipe 21 and the water part connecting pipe 22 for communication. The water level control cylinder 23 is connected to the heat receiving water pipe 3 through both connecting pipes 21 and 22, and therefore displays the same water level as the water level of the heat receiving water pipe 3. Is provided with detection ends for detecting the water level in the water level control tube 23 at two or more points. In this embodiment, the upper, middle and lower water levels in the water level control tube 23 are respectively detected. The upper detection end H, the middle detection end M, and the lower detection end L for detection are inserted and installed, respectively. These detection terminals H, M, L are configured to output the detected water level as a detection signal to the controller 24. The controller 24 which has received the detection signals from the respective detection ends H, M, L detects the rise time of the water level between the detection ends H, M, L, that is, the middle detection after the lower detection end L detects the water level. Time until the end M detects the water level and the middle detection end M
Time from when the water level is detected to when the upper detection end H detects the water level (that is, water supply time) and the fall time, that is, the time from when the water level leaves the upper detection end H to when it leaves the middle detection end M And the time from when the water level leaves the middle detection end M to when it leaves the lower detection end L (that is, the steam generation time), respectively, and in order to make the rising time and the falling time as long as possible, It has a self-learning function that determines the amount of water supply per unit. And the controller 2
4 indicates that when the heat load of the exhaust heat boiler 1 is low, the low load control range T ₁ is set, that is, the water level in the water level control tube 23 is between the upper detection end H and the middle detection end M. When the heat load of the exhaust heat boiler 1 is high, the water level in the water level control tube 23 is set to the high load control range T ₂ , that is, the water level in the water level control tube 23 is the middle detection end M and the lower detection end L. It is controlled so that it is between and. Further, the controller 24 determines the amount of water supply per unit time calculated according to both control ranges T ₁ and T ₂ based on the self-learning function, and uses this as a control signal to provide the water supply line 5. Output to the water supply pump P. That is, based on the measured rise time and fall time.
Next, when the water level inside the can rises and falls next time
Be sure to determine the amount of water supply per unit time in
This is the amount of water supplied per unit time when the water level in the can rises.
The interval and fall time are determined to be as long as possible.

In this configuration, as described above, the water supply valve 6 is turned on / off by the control signal from the water level controller 11, so that the water supply pump P is controlled by the controller 24. By changing the inverter frequency based on the above, the rotational speed, that is, the discharge amount to the heat receiving water pipe 3 is continuously changed. Therefore, by the control signal from the controller 24,
The discharge amount of the water supply pump P continuously changes, and the flow rate passing through the water supply valve 6 continuously changes. That is, the flow rate of the water supply valve 6 in one ON operation continuously changes, and the amount of water supply per unit time becomes appropriate. As a result, as shown in FIG. The interval of on / off operation becomes longer over time, and the number of on / off operations decreases. As a result, the on / off control by the water supply valve 6 becomes close to the proportional control. In other words, in this configuration, as a control of the amount of water supplied from the water supply line 5 to the heat receiving water pipe 3 per unit time, the flow rate of the water supply valve 6, which is on / off controlled, is used as a control signal from the controller 24. On the basis of,
The water supply pump P is used for adjustment.

Here, another preferred embodiment will be described as the control of the amount of water supplied to the heat receiving water pipe 3 per unit time. Not only the on / off control of the water supply valve 6 but also the on-off control If the opening degree, that is, the passing flow rate is continuously changed by the control signal from the container 24, the control can be performed only by the water supply valve 6. According to this, the passing flow rate continuously changes by one ON operation, and the amount of water supply per unit time becomes appropriate, and as a result, as shown in FIG. The interval of the off operation becomes longer with the lapse of time, the number of times of the on / off operation is reduced, and it becomes close to the proportional control. That is, depending on the implementation, control by the water supply valve 6 alone is also suitable.

[0021]

As described above, according to the present invention, the rising time of the water level in the can measured so that the proper water level determined based on the heat load of the exhaust heat boiler is maintained, and
Depending on the descent time, the next time the water level in the can rises and the water in the can
Since the amount of water supply per unit time during the descending position is controlled, the on / off control method is very close to the proportional water supply method, and it is possible to use an expensive sensor for proportional water supply control without using it. Water supply control can be implemented. In addition, along with this, it is possible to reliably prevent damage due to overheating of the heat receiving water pipe,
It is also possible to prevent impurities from precipitating due to the concentration of can water, which causes damage to the heat receiving water pipe. Furthermore, since it can be implemented with a simple structure and can be provided at a low cost, it is very effective for this type of water supply control.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of an exhaust heat boiler equipped with a water supply control device.

FIG. 2 is an explanatory view schematically showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship of water supply control in the embodiment of FIG.

[Explanation of symbols]

 1 Exhaust heat boiler 2 Inlet line 3 Heat receiving water pipe 4 Outlet line 5 Water supply line 6 Water supply valve 10 Water level detection end 11 Water level controller 12 Inlet temperature detector 13 Inlet temperature measuring device 14 Outlet temperature detector 15 Outlet temperature measuring device 17 Damper 18 Exhaust gas amount measuring device 19 Pressure calculator 20 Calculation processor 23 Water level control cylinder 24 Controller H Upper detection end M Medium detection end L Lower detection end P Water pump

Claims (2)

[Claims] 1. A number of heat receiving water pipes 3 are housed and arranged inside,
An exhaust gas inlet line 2 is connected to one side and an exhaust gas outlet line 4 is connected to the other side, and the heat receiving water pipe 3 is further connected.
The temperature difference of the exhaust gas at the inlet / outlet of the once-through type exhaust heat boiler 1 connected to the water supply line 5 for supplying water to the exhaust heat boiler 1 is detected, and the pressure loss value of the exhaust gas in the exhaust heat boiler 1 is also detected to detect the temperature difference and the pressure loss. Value is calculated to obtain the heat load of the exhaust heat boiler 1, and an appropriate value of the water level for the heat receiving water pipe 3 under the obtained heat load is determined, and the determined appropriate value and the heat receiving water pipe 3 The heat receiving water pipe 3 is compared with the actual water level and based on the comparison result.
In the water supply control device for the once-through type exhaust heat boiler configured to control the water supply level, the water level control cylinder 23 for detecting the water level of the heat receiving water pipe 3 is provided, and the water level control cylinder 23
The detection ends H, M, L for respectively detecting water levels at a plurality of points in the water level control cylinder 23 are inserted and installed therein, and the detection ends H, M, L are detected based on the detection signals from the detection ends H, M, L. The rise time and fall time of the water level during the period are measured respectively, and the time of the next rise of the water level in the can and the fall of the water level in the can are measured according to the rise time and the fall time.
That the unit to determine the amount of water supplied per time, the controller 24 for outputting a water supply amount of the determined as a control signal provided, the rotation of the feed water pump P provided in the water supply line 5 by the output signal from the controller 24 A water supply control device in a once-through type exhaust heat boiler, which is characterized by controlling the number. 2. The controller 24 continuously changes the opening degree of a water supply valve 6 provided in the water supply line 5 to control the amount of water supply per unit time.
The water supply control device for the once-through heat recovery boiler.