JP2777682B2 - Water level control method for once-through waste 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 level control of a boiler in which steam or hot water is obtained by using exhaust heat of an internal combustion engine, an incinerator, etc., and more particularly to a water level control method of a once-through type exhaust heat boiler. It is about.

[0002]

2. Description of the Related Art In general, a once-through-type exhaust heat boiler is disclosed in
-69602 and the like.
It is designed to satisfy a circulating water flow rate ratio of 1/2 or less as a water level up to the middle of the heat receiving water pipe, and a thermosiphon is configured with a rated heat load. However, when the heat load is reduced, a thermosiphon is not formed, 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 condensing water in the heat receiving water pipe. As a result, impurities are precipitated, which causes damage to the heat receiving water pipe.

Therefore, it is necessary to set the water level to an appropriate value according to the heat load. An example of such a method of setting the water level in a waste heat boiler is disclosed in JP-A-59-29901.
No. 1993. In this method, an exhaust gas temperature detector is provided in an exhaust gas inlet line of a waste heat boiler, and a water level is set by a signal from the temperature detector.

[0004]

In the above-described system for detecting the heat load from the exhaust gas source by detecting the temperature of the inlet line of the exhaust gas of the exhaust heat boiler at the outlet of the exhaust gas source, the exhaust gas from the exhaust gas source is detected. Although there is no problem when the amount is almost constant, when the amount of exhaust gas changes, there is a problem that the thermal load of the exhaust gas generation source cannot be determined only by detecting the temperature of the exhaust gas inlet line. The present invention can solve such a problem, reliably prevent damage to the heat receiving water pipe due to overheating, and prevent the precipitation of impurities due to the concentration of still water that causes damage to the heat receiving water pipe. Things.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in consideration of each load of an exhaust gas generation source.
Preset input condition to the waste heat boiler for the detects the in-can pressure the exhaust heat in the boiler to detect the temperature of the exhaust gas at the outlet of the waste heat boiler, the detected in-can pressure and exhaust gas temperature The input conditions are calculated to determine the heat load of the waste heat boiler, the appropriate value of the water level for the heat receiving water pipe under the obtained heat load is determined, and the determined appropriate value and the actual water level of the heat receiving water pipe are determined. comparing the door, but you are <br/> feature to control the water supply level of the heat receiving water pipe based on the comparison result.

[0006]

According to the water level control method of the present invention, the pressure inside the can in the exhaust heat boiler is detected, and the temperature of the exhaust gas at the outlet of the exhaust heat boiler is detected. Emissions for each load of the exhaust gas source
The heat load of the exhaust heat boiler is obtained by calculating the input conditions to the gas boiler and the appropriate value of the water level for the heat receiving water pipe under the obtained heat load is determined. Then, the appropriate value is compared with the actual water level of the heat receiving water pipe, and the water supply level of the heat receiving water pipe is controlled based on the comparison result .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail 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 using exhaust heat of an internal combustion engine, an incinerator, or the like.
FIG. 1 is an explanatory view schematically showing one embodiment.

In FIG. 1, an exhaust heat boiler 1 having a water level control device according to the present invention introduces exhaust gas from an exhaust gas generation source (not shown) such as an internal combustion engine or an incinerator from an inlet line 2 on one side thereof. Then, heat is exchanged with a plurality of heat receiving water pipes 3 housed and arranged therein to generate steam, and exhaust gas is discharged from the outlet line 4 on the other side.

The exhaust heat boiler 1 has a heat receiving water pipe 3 therein.
A water supply line 5 for supplying water into the inside is connected in communication. The water supply line 5 is provided with a water supply device (not shown) provided with a check valve, a filter, a chemical injection device, and the like. By operating the water supply pump P, water of an appropriate water source is filtered.
It is supplied into the heat receiving water pipe 3 of the waste heat boiler 1 as the chemical injection can water into which the chemical liquid has been injected. A water supply valve 6 for controlling water supply into the heat receiving water pipe 3 is provided downstream of the water supply pump P in the water supply line 5.

The exhaust heat boiler 1 is connected to an extraction line 7 for extracting steam generated by the heat receiving water pipes 3 through heat exchange with exhaust gas. This take-out line 7 is provided with a steam valve 8 to be taken out and used. Although a detailed description is omitted, this extraction line 7 includes:
In order to extract high-quality steam, an appropriate steam-water separator (separator) is provided.

The exhaust heat boiler 1 is provided with a pressure detector 9 for detecting the internal pressure inside the can. The pressure detector 9 detects the internal pressure of the exhaust heat boiler 1 that changes according to the change in the heat load during the operation of the exhaust heat boiler 1. When the pressure value becomes equal to or higher than the set pressure value, an alarm is appropriately generated.

The heat receiving water pipe 3 of the waste heat boiler 1 includes:
A water level detection end 10 for detecting an actual water level in the heat receiving water pipe 3 is provided. The water level detecting end 10 detects an actual water level in the heat receiving water pipe 3 which changes in accordance with a change in heat load during operation of the exhaust heat boiler 1, and uses the detected water level as a detection signal to perform water level control. Table 11
Output to

Further, a temperature detector 12 for detecting the temperature of the exhaust gas discharged from the exhaust heat boiler 1 is provided at the outlet line 4 of the exhaust heat boiler 1. The temperature detector 12 detects the temperature of the exhaust gas in the outlet line 4 and uses the detected temperature as a detection signal as a temperature measuring device 13.
Output to

[0014] Now, the water level control device according to the present invention, exhaust
Waste heat boiler for each load (different load) of gas generation source
Input conditions to 1 (exhaust gas temperature and exhaust gas from exhaust gas generation source)
Gas amount) set in advance, and detects the in-can pressure waste heat boiler 1, to detect the temperature of the exhaust gas in the outlet line 4 of the waste heat boiler 1, said and the can internal pressure and the detected temperature
The heat load of the waste heat boiler 1 is determined from the input conditions and the water level of the heat receiving water pipe 3 is controlled according to the heat load. Calculation of this heat load and setting of the water level
An arithmetic processing unit 14 for performing the setting is provided. The processing unit 14 receives the exhaust gas temperature at the outlet line 4 as a detection signal from the temperature measuring device 13 via the temperature detector 12, and detects the pressure in the can in the exhaust heat boiler 1 from the pressure detector 9. It is configured to receive as a detection signal. Calculation processor 14 which receives the two detection signals from said input conditions as in-can pressure and the exhaust gas temperature of its <br/>, determining the thermal load of the exhaust heat boiler 1 during the detection, the heat load The appropriate value of the water level of the heat receiving water pipe 3 according to the above is determined.
Then, an appropriate value of the determined water level is output to the water level controller 11 as a control signal.

Then, the water level controller 11 which has received a control signal of an appropriate water level for the heat receiving water pipe 3 from the arithmetic processing unit 14 outputs the control signal and the actual water level from the water level detecting end 10 of the heat receiving water pipe 3. Comparison with the detection signal of
Based on the comparison result, an open / close control signal for controlling opening / closing of a water supply valve 6 provided in the water supply line 5 is output. 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. Heat-receiving water according to the heat load
In this embodiment, the appropriate value of the water level of the pipe 3 will be described later.
As shown in Fig. 3, when the heat load of the waste heat boiler is low,
Is the water level in the low load control range T1, and the exhaust heat boiler
When the heat load of the high load control range T2 is high,
It is.

The water supply control of this embodiment is performed according to the heat load.
Water level appropriate value setting function and water supply amount per unit time
It has an appropriate function. These functions will be described with reference to FIGS. In FIG. 2, as a specific example of the water level detection end 10, there is provided a water level control cylinder 17 which is connected to the heat receiving water pipe 3 by a steam communication pipe 15 and a water communication pipe 16. This water level control cylinder 17
Is connected to the heat receiving water pipe 3 through both the communication pipes 15 and 16 to display the same water level as that of the heat receiving water pipe 3.
A detection end for detecting the water level in the water level control cylinder 17 is provided at a plurality of points above the location, and in this embodiment, an upper detection for detecting the upper, middle, and lower water levels in the water level control cylinder 17 respectively. An end H, a middle detection end M and a lower detection end L are inserted and installed, respectively. this
In the configuration, a water level appropriate value setting machine according to the heat load
When the thermal load of the pre Kihainetsu boiler 1 To explain the ability is low, so that the low-load control range T _1, i.e. the water level higher detecting end H and median detection end M of the water level control cylinder 17 , And when the heat load of the exhaust heat boiler 1 is high, the water load in the high load control range T ₂ , that is, the water level in the water level control cylinder 17 is lower than the middle detection end M and lower. Control is performed so as to be between the detection end L. These controls are based on each detection signal from each detection end H, M, L based on the water level shown in FIG.
Water level calculator 1 that functions as controller 11 and processor 14
8 is performed. This water level calculator 18 is a unit time
It has a function to make the amount of water supply per unit appropriate,
The rise time and fall time of the water level in both control ranges T ₁ and T ₂ are measured, and a signal for controlling the water supply valve 6 or the water supply pump P is output in accordance with each measured value.

In this configuration, the water supply valve pertaining to the control signal from the water level calculator 18 is controlled by the control signal from the water level calculator 18 so that the water supply amount per unit time becomes appropriate. in the 6, is configured such that the opening is continuously changed, so that its opening degree continues to change communication based on the control signal, it has rows proportional feedwater in response to this variation diagram As shown in 3, the water level
Change. In the said feed water pump P which receives a control signal from or water level calculator 18, the rotational speed is continuous target on the basis of the rotational speed is configured to continuously change, thus the control signal changes in water level changes as shown proportional feedwater line had Figure 3 in response to this change.

As described above , in addition to the water level control according to the heat load, the water supply control is performed so that the water supply amount per unit time is appropriate, thereby maintaining an appropriate water level according to the heat load. The water supply amount per unit time can be made appropriate at the appropriate water level.

[0019]

As described above, according to the present invention, the exhaust gas
The heat load is determined based on the input conditions to the exhaust heat boiler for each load of the heat source , the pressure inside the can in the exhaust heat boiler, and the temperature of the exhaust gas at the outlet of the exhaust heat boiler. Because the appropriate value of the water level for the water pipe is determined, the determined appropriate value is compared with the actual water level of the heat receiving water pipe, and the water supply to the heat receiving water pipe is controlled based on the comparison result. Even when the amount of exhaust gas from the exhaust gas source changes, the heat load of the exhaust gas boiler can be accurately determined, the water level of the heat receiving water pipe can be controlled reliably, and damage due to overheating of the heat receiving water pipe can be reliably prevented. Can be prevented. In addition, it is possible to prevent the precipitation of impurities due to the concentration of still water which causes damage to the heat receiving water pipe.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing an example of a water supply control device added to the embodiment of FIG. 1;

FIG. 3 is an explanatory diagram showing a relationship between a control signal and proportional water supply in the embodiment of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste heat boiler 2 Inlet line 3 Heat receiving water pipe 4 Outlet line 5 Water supply line 6 Water supply valve 9 Pressure detector 10 Water level detection end 11 Water level controller 12 Temperature detector 13 Temperature measuring device 14 Arithmetic processor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-103905 (JP, A) JP-A-59-29901 (JP, A) Jikai Sho 61-69602 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) F22D 5/00 B F22D 5/24

Claims (1)

(57) [Claims] An exhaust heat boiler for each load of an exhaust gas generation source.
Set the input condition to La advance, detects the in-can pressure waste heat boiler 1, to detect the temperature of the exhaust gas at the outlet of the waste heat boiler 1, the input and the detected in-can pressure and exhaust gas temperature The heat load of the waste heat boiler 1 is obtained by calculating the conditions and the heat load of the heat receiving water pipe 3 is determined under the obtained heat load, and the determined appropriate value and the actual value of the heat receiving water pipe 3 are determined. A water level control method for a once-through type exhaust heat boiler, comprising comparing a water level with a water level and controlling a water supply level of the heat receiving water pipe 3 based on the comparison result.