JPH0926106A - Method for preventing filling-up of water during shutdown of boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent water from flowing into a boiler and eliminate the drive of a water supply pump during its shutdown, and enhance its safety by driving the water supply pump and closing a motor-operated valve when a boiler water pipe temperature during its shutdown has dropped to a preliminarily determined value. SOLUTION: A number of-unit control device 24 transmits a combustion signal and a shutdown signal of each of boilers (No.1 No.4) to each controller 13 by a preliminarily determined order based on a signal from a pressure sensor 23 of a steam header 22. The boiler which has received the shutdown signal stops combustion and turns to a stand-by status. The boiler which has stopped the combustion drops the temperature of water pipes with the lapse of time. When the temperature of the water pipes drops to the preliminarily determined value, a temperature sensor detects this and informs this detection signal to a controller 13. The controller 13 drives a water supply pump 15 for a designed time based on the signal from the temperature sensor and then closes a motor- driven valve 18.

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 water full while a boiler is stopped.

[0002]

2. Description of the Related Art Generally, in a multi-can installation system in which a plurality of boilers are installed, a pressure detector is provided in the steam header to grasp the load state, and the required number of units are sequentially switched to combustion according to the load amount. There is a well-known method for controlling the number of boilers in which a load is controlled by a unit control device that burns / stops the boiler according to the fluctuation.

By the way, a water supply source valve for supplying water to each boiler to which the above-described method for controlling the number of boilers is applied is interlocked with an operation switch of the above-mentioned number-of-units control device. Therefore, in the boiler which is stopped (standby) when the unit control device is ON, the internal pressure of the can may decrease and become a negative pressure. When the internal pressure of the can becomes negative, water may be sucked from the water supply line and the inside of the can may become full.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a method for preventing water full while the boiler is stopped.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and has a structure in which a water supply line connected to a boiler is provided with a check valve, a water supply pump and an electric valve. When the temperature of the water pipe during the stop of the boiler is reduced to a preset temperature, the electric valve is closed after driving the feed water pump for a set time t ₁ , and if there is a combustion request in the stopped boiler, It is characterized in that the electric valve is opened and the set time t _{2 is} delayed to drive the water supply pump.

[0006]

According to the present invention, when the boiler water pipe temperature during stop has fallen to a preset temperature, the electric water supply pump is driven for a set time and then the electric valve is closed. After opening the valve and delaying the set time, the water supply pump is driven.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view showing the arrangement of a multi-can installation system for a boiler embodying the present invention, and FIG. 2 is an illustration showing the configuration of the boiler of the multi-can installation system shown in FIG. Reference numeral 1 denotes a boiler, and a plurality of boilers (No. 1 to No. 4) are installed. Each boiler has a steam pipe 21 connected to a common steam header 22, and a pressure sensor 23 of this steam header 22 is connected. Based on the detection signal of
This controls the combustion and stoppage of each boiler. The unit number control device 24 and the controller 13 of each boiler are
Each is connected via a line 25. Code 26
Indicates the detection signal from the pressure sensor 23 by the unit number control device 24.
The reference numeral 27 is a water tank.

In FIG. 2, the boiler 1 includes a can body 6 in which a combustion chamber 5 is formed in a central portion by connecting a plurality of water pipes 4 between an upper header 2 and a lower header 3 which are annularly formed. A burner 7 as a heating means is arranged above the can body 6. A fuel supply line 8 is connected to the burner 7, a fuel pump 9 and a fuel electromagnetic valve 10 are inserted in this line, and combustion air is sent to the burner 7 by a blower 11. A pressure sensor 12 for detecting the vapor pressure is provided at one end of the upper header 2. Code 14
Is a water level detector for detecting the water level in the can body 6, and in the water supply line 15 connected to the lower header 3 by an appropriate water level control device based on the signal of the water level detector 14. The water supply pump 16 is turned on and off to keep the water level in the can at a constant level. Sign 1
Reference numeral 7 is a check valve provided in the water supply line 15, reference numeral 18 is an electric valve, and the other end of the water supply line 15 is connected to the water storage tank 27. A temperature sensor 19 is provided at a predetermined position above the water pipe 4, and the temperature sensor 19, the water supply pump 16, the electric valve 18, and each device attached to the boiler 1 are connected to the controller 13 via a line 20. ing.

A method for preventing full water during the stoppage of the boiler 1 in the multi-can installation system configured as described above will be described. Combustion and stop of each of the boilers (No. 1 to No. 4) are controlled by the controller 13 of each of the boilers based on a signal from the unit number control device 24. That is, based on the signal from the pressure sensor 23 of the swimmer header 22, the unit number control device 24 sets the boilers (N) according to a preset order.
o. 1 to No. 4) Combustion / stop signal is sent to each controller 1
Call 3. Therefore, the boiler (for example, No. 4) that has received the stop signal stops combustion and enters the standby state. In the boiler that has stopped burning, the pressure in the can decreases and the temperature of the water pipe 4 also decreases over time. Therefore, in the present invention,
When the temperature of the water pipe 4 drops to a preset temperature,
The temperature sensor 19 detects, and this detection signal is sent to the controller 1
Report to 3. The controller 13 controls the temperature sensor 19
After driving the water supply pump 16 for a preset time t ₁ (for example, 5 seconds) based on the signal from the motor drive valve 18, the electric valve 18 is closed. If the boiler 1 in the stopped state has a combustion request, the controller 13 opens the motor operated valve 18 and delays the preset time t ₂ (for example, 5 seconds) before driving the water supply pump 16. .

As described above, when the temperature of the water pipe of the stopped boiler is reduced to the set temperature, it is judged that there is no self-evaporation in the boiler can. However, the water level in the can reaches the lower limit water level position of the water level control device. In some cases, the water supply pump 1
In order to prevent 6 from being driven, the controller 13 _first drives the water supply pump 16 for a predetermined time t ₁ and then closes the electric valve 18 to prevent water from flowing into the can. Further, if there is a combustion request for the boiler that is stopped, in order to open the electric valve 18 first and bring the water supply line 15 into the can, the water supply pump 16 is delayed by a predetermined time t ₂ after the electric valve is opened. Drive it. Therefore, it is safe because the water supply pump 16 is driven with the electric valve 18 opened. The present invention is not limited to a boiler having a multi-can installation system, but can be applied to a boiler having a single-can installation.

[0011]

As described above, according to the present invention, when the temperature of the boiler water pipe in the stopped state drops to a preset temperature, the electric water supply pump is driven for the set time and then the electric valve is closed. Therefore, it is safe because it is possible to prevent the water from flowing into the can and to drive the water supply pump during stoppage. Further, if there is a combustion request for the boiler that is stopped, the electric valve is opened to delay the set time to drive the water supply pump, which is safe.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an arrangement of a boiler embodying the present invention in a multi-can installation system.

FIG. 2 is an explanatory diagram showing a configuration of a boiler of the multi-can installation system shown in FIG.

[Explanation of symbols]

 1 Boiler 4 Water pipe 15 Water supply line 16 Water supply pump 17 Check valve 18 Motorized valve

Claims (1)

[Claims] 1. A water supply line 15 connected to a boiler 1,
In the configuration including the check valve 17, the water feed pump 16, and the motor-operated valve 18, when the temperature of the water pipe 4 during the stop of the boiler 1 drops to a preset temperature, the water feed pump 16 is driven for a set time t _1. After that, the motor-operated valve 18 is closed, and if there is a combustion request for the boiler 1 that is stopped, the motor-operated valve 18 is opened to delay the set time t ₂ to drive the water supply pump 16. To prevent full water in.