JP2988309B2 - How to prevent overheating of boiler water tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing overheating of a water pipe for a boiler.

[0002]

2. Description of the Related Art Conventionally, a means for preventing overheating as a safety device for a water pipe for a boiler is provided with a temperature sensor at an upper portion of the water pipe and a heat-resistant limit temperature of the water pipe (for example, 350 ° C.)
When the temperature sensor detects the heat-resistant limit temperature, the boiler issues an alarm and stops. That is, FIG.
As shown in, but normally has reached the top of the water pipes 21 boiler water boils to prevent overheating of the water pipe 21, when the water supply amount is insufficient by some factors, as shown in FIG. 5
In some cases , the water level in the can is lowered, and the upper part of the water pipe 21 is overheated to near the heat-resistant limit temperature.

[0003]

OBJECTS OF THE SUMMARY This invention is aimed at pre-view of the problems of the above, the following heat-resistant limit temperature of the water tube, yet provide a water tube overheat preventing method corresponding to the steam pressure .

[0004]

SUMMARY OF THE INVENTION This invention was made to solve the previous SL problems, according to claim 1
The invention relates to a boiler having a configuration in which an upper header and a lower header are connected by a number of water pipes, and a water supply line having a water supply pump is connected to the lower header.
And a pressure sensor at a predetermined location on the water pipe.
A temperature sensor is provided and the feed pump, pressure sensor and
This control <br/> control vessels with connecting pre said temperature sensor to the controller, enter the saturation temperature and overheat prevention temperature of the water tube 4 which is set in advance with respect to saturation temperature for the steam pressure, the controller Is the pressure detected by the pressure sensor
Set the overheating prevention temperature based on the force, and
Thus it is characterized by forcibly driving the feed water pump when the temperature of the water tube detected reaches the overheat prevention temperature.

[0005]

SUMMARY OF] According to the present invention, the temperature of the water pipe, saturated steam
When the overheat prevention temperature corresponding to the temperature is reached, the water supply pump is forcibly driven via the controller.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall explanatory view showing a cutaway part of a can body of a multi-tube once-through boiler embodying the present invention.
In FIG. 1, a can body 1 has an upper header 2 formed in an annular shape.
And the lower header 3 are connected by a number of water tubes 4 to form a combustion chamber 5 in the center . This combustion chamber 5
A burner 6 as a heating means is arranged on the upper part of the heater. This burner 6 is connected to a fuel supply line 7, this
A fuel pump 8 and a fuel solenoid valve 9 are connected to the fuel supply line 7.
Is provided. The combustion air is sent to the burner 6 by a blower 10. One end of the upper header 2
Is provided with a pressure sensor 11 for detecting steam pressure.
You. Then, the burner 6, wherein is thus controlled by the control unit 12 based on the signal of the pressure sensor 11. That is, the combustion of the a-can steam pressure exceeds the high set pressure burner 6 is stopped, and controlled to start the combustion of the burner 6 and turn off the low set pressure. Also, an appropriate water level control device
The water level detector 13 for detecting the water level of the can body 1
The water supply pump 15 in the water supply line 14 connected to the lower header 3 is turned on and off based on the signal from the controller 3 to keep the water level in the can at a constant level.
Foregoing with each device 8,9,11,15 and the controller 12
It is connected by a line 16. Reference numeral 17 in the figure denotes a refractory material.

[0007] The temperature sensor 18 provided at a predetermined position of the top of the water pipe 4, Oh Ru connect this temperature sensor 18 to the controller 12 via line 16. The controller 12 includes an arithmetic and memory functions, and a saturation temperature for the steam pressure shown in FIG. 2, the preset overheat prevention temperature is entered for this saturation temperature.

[0008] In the overheat preventing method of the present invention, for example, a saturation temperature of about 180 ° C. in the boiler water setting steam pressure of the boiler from 9 kg / cm ² Tosureba 2 is Ru sought. Also,
For clean water pipe, as shown in FIG. 3, the temperature of the combustion gas
Degrees outer temperature water pipe when the 800 ° C. is about 203 ° C., a water pipe side temperature 196 ° C.. Further , the heat-resistant limit temperature of the water pipe 4 is set to 350 ° C. As shown in FIG. 2, the overheat prevention temperature in the present invention is the temperature T ₁ (for example, 100 ° C.) corresponding to the saturation temperature with respect to the set steam pressure.
Is added and set. That is, when the operating pressure of the boiler changes , the reference value of the overheating prevention temperature of the water pipe 4 is corrected by the change of the saturation temperature with respect to the change of the used steam pressure.
Then, the superheated phenomenon water tube 4 occurs, notifies the signal from the temperature sensor 18 and reaches the overheat prevention temperature to the controller 12 via the line 16. Received a report
The controller 12 checks the signal from the temperature sensor 18 with the steam pressure signal from the pressure sensor 11, determines that the water pipe is overheated, and forcibly drives the water supply pump 15. Therefore, although the water pipe 4 does not reach the heat-resistant limit temperature, water is forcibly supplied in a state where the water pipe 4 is slightly overheated than the normal water pipe temperature to lower the water pipe temperature, so that it is safer.

[0009]

As described above, according to the present invention, the saturation temperature with respect to the steam pressure and the overheating prevention temperature of the water pipe set in advance with respect to the saturation temperature are input to the controller, and the upper temperature detected by the pressure sensor is detected. To the pressure in the header
Based set overheating prevention temperature, the temperature of the water pipe is to be forcibly driven feed water pump when it reaches the overheat prevention temperature until heat limit temperature of the water pipe is not reached, the normal water pipe temperature Water is forcibly supplied in a slightly overheated state, so that deterioration from metal fatigue due to overheating of the water pipe can be prevented. Further, the water pipe is not overheated to the heat-resistant limit temperature, and therefore, the boiler is not stopped due to the overheating of the water pipe, which is efficient.

[Brief description of the drawings]

FIG. 1 is a partially cutaway explanatory view showing a can body of a multi-tube once-through boiler embodying the present invention.

FIG. 2 is an explanatory diagram showing a relationship among a boiler steam pressure, a canister water saturation temperature, a normal water pipe temperature, a superheat set temperature, and a water pipe heat resistant limit temperature according to the present invention.

FIG. 3 is an explanatory diagram showing a combustion temperature, a water pipe temperature, and a saturation temperature at a steam pressure of 9 kg / cm ^{2 in} a clean water pipe.

FIG. 4 is an explanatory diagram showing a state in which can water is boiling up to an upper part of a water pipe of a multi-tube once-through boiler.

FIG. 5 is an explanatory diagram showing a state in which boiler water is not very boiling in a water pipe of a multi-tube once-through boiler.

[Explanation of symbols]

 2 upper header 3 lower header 4 water pipe 11 pressure sensor 12 controller 14 water supply line 15 water supply pump 18 temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-U 3-112611 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F22D 5/26

Claims (1)

(57) [Claims] An upper header (2) and a lower header (3) are connected by a number of water pipes (4).
When a pressure sensor 11 is provided on the upper header 2 in a boiler having a configuration in which a water supply line 14 provided with
In addition, a temperature sensor 18 is provided at a predetermined location of the water pipe 4,
The water supply pump 15, the pressure sensor 11, and the temperature
This controller 12 with connecting degree sensor 18 to the controller 12 receives the overheat prevention temperature of the water tube 4 which is set in advance with respect to the saturation temperature and the saturation temperature for the steam pressure, the controller 12, the By the pressure sensor 11
Set the overheating prevention temperature based on the detected pressure, and
Overheating preventing method of the boiler water pipe, characterized in that the temperature of the water tube 4 detected by the degree sensor 18 is forcibly drives the water supply pump 15 when reaching the overheat prevention temperature.