JPS5932702A - Preventive device for superheat of boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a water level detection device f which is provided to guide the water level inside the boiler to the outside of the boiler, such as in a multi-tubular once-through boiler.
This invention relates to an overheat prevention device for a boiler that controls the operation of the boiler.

The first example of the water level control mechanism in a conventional boiler of this type is shown below.
As shown in the figure, in a boiler formed by connecting an upper header 1 and a lower header 2 with a large number of water pipes 3, connecting pipes 12 and 13 are connected from the upper header 1 and the lower header 2 to each other using connecting pipes 12 and 13. A float type or 'electrode type water level detector 8 is installed in the water level control node 4 as a water level detection device that guides the water inside the boiler to the outside.
9 and 10° 11 are provided, and the starting and stopping of the water supply pump 6 and the burner 7 are controlled via the controller 5 based on the signals from these detectors.

Water level detector 5Iri lowest water level (minimum water level d) f
This is a detector for detection and is used as a ground electrode.

The other three water level detectors 9, 10, and 11 are used as electrical currents on the anti-ground side. The water level detector 9 detects the water level C' and starts the combustion of the burner 7 (the water level increases and the water level CKa
(when the water level has decreased and reached water level C) and a stop signal (when the water level has decreased and reached water level C). The water level detector 10 detects the water level completely (-starts the water supply pump 6 (when the water level decreases and reaches the water level)), and the water level detector 11 detects the water level ak and issues a signal to stop the water supply pump 6 (when the water level decreases and reaches the water level). When the water level increases and reaches the water level aK), the first signal is issued.

With this system, the water level is maintained between a and b during normal operation, and when the water level drops below C, the burner 7 completely stops combustion due to the sound of overheating in the water pipe 3. It has become.

In this German boiler, the water level inside the boiler, especially in the water pipes, is unstable and difficult to clearly detect, so water is detected outside the boiler and a separate water level detection device is installed. The water level is detected by
In the above-mentioned equipment, the water level in the boiler and the water level? 1. It is difficult to completely prevent the water from overheating because the difference between the water level and the water level in the J-tube 4 varies depending on the boiler's evaporation, combustion amount, canned water temperature, etc. In addition, if the connecting pipe 12 or 13 becomes clogged or frozen, the burner 7 will not be able to burn even if the water level falls below the water level C, causing a dry firing accident.

In order to improve this drawback, the v/lle was
12405, there is also a water level construction method [1 unit installed in the upper pipe header, and a method in which the water supply pump is activated at t7 by adding a time factor. There is no mechanism to stop the water supply, and there is a time factor involved, and the performance of the water supply pumps is different due to the amount of evaporation and pressure K!, and it is not possible to replenish a constant water supply, so all works to prevent nitrogen burning] Indeed, Yukino: Unoshi↓It was difficult.

The present invention eliminates the above-mentioned drawbacks of the conventional ones, and provides a boiler overheating prevention device that can directly detect the entire water level in the water pipes, reliably prevent overheating of the water pipes, and prevent dry firing accidents. ``The objective is to provide a.

The present invention detects the water level in the boiler with a water level detection device installed to guide the water in the boiler to the outside of the boiler, and operates the boiler's water supply pump and combustion via a closed contact.
In the overheating prevention device for a boiler that is designed to control the water level, a water level detector for starting/stopping the water supply pump and a water level detecting for starting/stopping the combustion are also installed in the water level detecting device. ] Connect a safe water level detection end kL to a safe water level that does not generate heat, and connect the safe water level detection end to the common ground terminal of the water pump start/stop water level output circuit and the combustion start/stop water level detection circuit. This is a boiler overheat prevention device characterized by the following features.

This book also explains the 14th page of Akira's practicing doctor in January, the 2nd L.
17.1 and Fig. 3, water level detector 8 shows water% 3
q], and its detection water fILd'id:-:-
The water level for starting and stopping water pipe 3 is at a higher level than CI, and even if the water level is so high when the button is turned on, it is the water level at which water pipe 3 does not overheat. The detection circuit and control circuit will be explained with reference to FIG.
The other water level detector 9.10.31 is connected to the anti-ground side.

A water level detector 9 that detects the boiler combustion start/stop water level C is connected to the AC power source 14 through the seal 15 and forms a combustion start/stop water level detection circuit together with the water level detector 8. A water level detector 10 that detects the water level when starting the water supply pump is connected to the AC power supply 14 through the Vi contacts 16 and lj L/-17, and together with the water level detector 8, the entire water level detection circuit for starting the water supply pump is formed.C Stopping the water supply pump A water level detector 111-i for detecting the water level a is connected to the AC power source 14 via the relay 17 mentioned above in common 7, and together with the water level detector 8 forms a water pump stop water level detection circuit. That is, the water level detector 8 i4 which is a safe water level detection terminal serves as a common ground terminal for the water supply pump start/stop water level detection circuit and the combustion start/stop water level detection circuit. As for the control circuit, a contact 18 is connected to the water supply pump 6, and a time-limited return contact 21 is connected (-) to the 7-ring 19 of the burner 7 and the fuel supply valve 20 (electromagnetic valve).

Explain the operation ○ When the inside of the water pipe 3 becomes boiling in a steady state,
The water level in the water pipe 3 rises relative to the water level in the water level control tube 4,
The grounding of the water level detector 8 is maintained continuously. For this reason,
When the water level inside the water level control tube 4 decreases from the starting water level, water is supplied, -j? When the pump 6 is activated and the water level rises, and reaches the stop water level aiC, the water supply cylinder 6 is stopped, and this process is repeated until the water level is maintained between 1ria and 1ria-b.

During operation, for some reason the water level in the water pipe 3 drops to the safe level d'.
When the water level becomes lower, the water level detector 8 is no longer grounded, the contact 18 is closed by the action of the relay 17, and the water supply and bump 6 are activated regardless of the water level in the water level control tube 4.

Even if the water supply pump 6 is activated, the water level in the water pipe 3 does not return to the safe water level d' within the specified time, or has the water level in the water level control tube 4 fallen below the water level C after a specified period of time? However, if the water level does not return to C even if the water level C is reached, combustion is stopped by the action of the time-limited return contact 21 to prevent overheating. The reason why the time-limited return contact 21i is used here is to prevent chattering, which occurs because the water level in the water pipe 3 fluctuates violently in a turbulent state.

At the time of startup, no boiling is occurring, so the water level in the water pipe 3 and the water level in the water level control tube 4 are almost the same. The water pump 6 continues to operate until the water level reaches the safe water level d', and then the water level rises, and only when the water level reaches the safe water level d' does the water pump 6 stop and combustion begin.

In this way, when combustion starts at startup and the power is 5, the water pipe 3
Since the water level inside has already reached the safe water level d', there is no risk of the water pipe 3 overheating and causing a dry firing accident.

FIG. 4 shows a detection circuit of another embodiment, in which the combustion start/stop water level C and the water supply pump start water level are made to match, and the water level detectors 1 to 10 are also used as the water level detector 9. One detector can be omitted.

Although the multi-tube once-through boiler has been described above, the present invention also applies to the water level in the boiler, regardless of the type of boiler.
The present invention can be applied to boilers in which the difference between the water level in the water level control cylinder and the water level changes due to combustion.The present invention prevents water pipes from running dry due to insufficient water level and overheats the boiler, regardless of startup, steady operation, or abnormal conditions. It is possible to provide a boiler overheat prevention device that can reliably prevent O

[Brief explanation of the drawing]

Fig. 1 is a flow diagram of the conventional example, and Fig. 2 is a flowchart of the present invention [9].
Figure 3 is the detection and control circuit diagram, Figure 4 is the flow diagram of the
The figure is a detection circuit diagram of another implementation row.Congratulations 1..."Two-part header, 2...Lower header, 3...Water/ul
4...Water level control tube, 5...? li! I goki,
6...Water pump, 7...Burner, -8,9
, 10, 11... water level detector, 12.13...
Connection pipe, 14... AC illumination, 15... Relay, 16... Contact, 17... Relay, 18.
...Contact, 19...Fan, 20...Fuel supply valve, 21...Time-limited return contact. Patent Applicant Ebara Corporation Representative Patent Attorney Go-Chi Hatayama 1) Minoru 1

Claims (1)

[Claims] 1. In a boiler overheat prevention device that controls the operation of the boiler by detecting the water level in the boiler with a water level detector A installed inside the boiler and guided outside the water/metal boiler, A water supply pump start/stop water level detector and a combustion start/stop water level detector are installed in the boiler, and a safe water level detection end is installed at a safe water level in the boiler that does not cause overheating even if combustion is performed, and a safe water level detection end is installed in the boiler to detect the safe water level. An overheating prevention device for a boiler, characterized in that the end is a common ground terminal of the water pump start/stop water level detection circuit and the combustion start/stop water level detection circuit.