JPH0120681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for preventing overheating and corrosion of water pipes in a once-through boiler.

[Prior art] Traditionally, once-through boilers that maintain a constant water level of canned water in water pipes are smaller and safer than other boilers, so they do not require boiler inspections and can be independently managed. It is widely used as an energy-saving boiler due to its excellent thermal efficiency.

However, large-sized boilers are fire tube and water tube boilers, which have a long lifespan of 15 to 20 years, whereas once-through boilers generally have a lifespan of 3 to 7 years, depending on management conditions. Its biggest drawback is that it is short.

This is thought to be caused by the following phenomenon. Once-through boilers have a small amount of water, and
Because no convection occurs, scale builds up quickly. This scale cannot be completely removed even with chemical treatment, and cleaning with a wire brush or the like is difficult due to its structure. In addition, in once-through boilers, the water level of the canned water in the water pipes is kept constant, so areas where scale is likely to adhere are fixed, and abnormal overheating occurs there due to the insulating effect of scale. Furthermore, since the water surface is always in contact with a certain part of the water pipe, the metals that make up the water pipe turn into ions due to the release of dissolved oxygen during evaporation of canned water or the electromotive force generated with the water surface as a boundary, causing ions to form in the canned water. It elutes, and the area near the water surface becomes abnormally corroded. This results in a shorter lifespan than other boilers.

[Objective of the Invention] The present invention provides a method for preventing overheating of water pipes and corrosion in the water pipes near the water surface of the boiler, and a device therefor, thereby significantly extending the life of a once-through boiler. The purpose is to

[Structure of the Invention] The gist of the present invention is to provide: a water pipe that converts internal canned water into steam by being heated; and a first pipe body that communicates with the water pipe and collects steam from the water pipe. In a water pipe overheat corrosion prevention device for a once-through boiler, comprising: a second pipe body that communicates with the water pipe and supplies canned water to the water pipe; and a water level adjustment means for adjusting the water level of the canned water to a predetermined water level. , the water level adjustment means includes a plurality of water level detection units that detect different set water levels of canned water, a set water level switching unit that automatically switches the set water levels corresponding to the detection units using a timer as a parameter, and a water pipe. A water pipe overheating corrosion prevention device for a once-through boiler is characterized by having a water level adjusting section that adjusts the water level of the can to a set water level set by the set water level switching section by controlling the water supply amount of the boiler.

The basic configuration of the present invention will be explained with reference to the illustrative diagram of FIG. Here, 11 is a water pipe, 12 and 13 are pipe bodies, 14 is canned water supplied from the outside, 14a is the water surface of the canned water 14 in the water pipe 11, and 15 is the canned water 14 heated in the water pipe 11. This is the steam generated.
Further, 16 is a water level adjusting means having a plurality of water level detecting sections 16a, a set water level switching section 16b, and a water level adjusting section 16c. When the water level is set, the water level detecting section 16a corresponding to that water level is activated, and the water level adjusting section 16c is controlled so as to reach the set water level, thereby adjusting the can water level 14a.

[Example] Next, the configuration of an example of the present invention will be described with reference to the drawings.

FIG. 2 is a front partial sectional view showing the main parts of a once-through boiler 20 as an embodiment of the present invention, and FIG.
The figure is a plan view of the main part.

A ring-shaped upper and lower pipe body 2 in which the upper and lower ends of a large number of vertical water pipes 21 arranged at equal intervals on the circumference are connected to each other.
2, 23, a safety valve 24 is installed in the upper header body 22.
In addition, a cleaning port 25 that also serves as an inspection port for each vertical water pipe 21 is formed on the axis of each vertical water pipe 21, and a water pipe pipe cap 26 is removably attached to each cleaning port 25, and a water pipe pipe cap 26 is removably attached to the bottom pipe pipe 21. The body 23 is equipped with a water supply control valve 27 for adjusting the amount of water supplied thereto, and a blind lid 28 for opening the door, and each of the upper and lower pipe bodies 2
A steam separator 29 and a water level detection tube 30 are installed between 2 and 23.
is installed. This steam/water separator 29 is equipped with a main steam valve 31 for supplying steam to the outside, an air intake port 32 is formed, and a water level detection pipe 30 is provided with a water level detection pipe 30 that measures the water level of canned water 33 in the vertical water pipe 21. A water level gauge 34 is installed to visually check the water level.

Further, as shown in FIG. 4, the main body case 35 of the water level gauge 34 is equipped with a water supply start signal that outputs a water supply start signal when the water level of the canned water 33 in the vertical water pipe 21 drops to a preset low water level necessary to ensure boiler operation. A floatless water supply start water level detection switch 36 to be output, and a float to output a burner cut signal to stop the boiler operation when the water level of the canned water 33 in the vertical water pipe 21 drops to a preset lowest water level that will interfere with the boiler operation. The burner cut water level detection switch 37 and the water level of the canned water 33 in the vertical water pipe 21 have risen to any plurality of upper limit water levels (set water levels) preset in response to boiler operation, in this case two upper limit water levels. Floatless water supply stop water level detection switches 38 and 39 that output a water supply stop signal for each water level are sometimes installed, and the water supply stop water level detection switches 38 and 39 output the water supply stop signal to the boiler control electric circuit 40. A switching device for changing the water level of the canned water 33 in the vertical water pipe 21 at the time of water supply stop to two levels, upper and lower by switching signals for each water level. It is connected between the control electric circuit 40 and the control electric circuit 40 . This switching operation of the timer switch 44 is automatically performed by the electric circuit 40 according to the passage of time by a tire provided therein.

In FIG. 3, reference numeral 42 denotes a burner for heating the water pipe 21, which is attached to the center of the upper header body 22 and is controlled by the output from the boiler control electric circuit 40 together with the water supply control valve 27. be.

In the above-described configuration, the water supply stop water level detection switches 38 and 39 correspond to a plurality of water level detection units, the timer switch 44 corresponds to a set water level switching unit, and the combination of the boiler control electric circuit 40 and the water supply control valve 27 corresponds to the water level detection unit. This corresponds to the water level adjustment section.

Next, the operation of this embodiment will be explained.

In the once-through boiler 20 configured as described above, if the electric circuit 40 is initially controlled by switching the timer switch 44 to the state shown in FIG. is connected to the canned water 3 in the vertical water pipe 21
The water level at the time of water supply stop in step 3 is set to the higher of the two levels, upper and lower. For example, after one day's boiler operation is completed at this water level, when the electric circuit 40 switches the timer switch 44 to a state opposite to that shown in the figure the next day due to a 24-hour timer count, the water supply stop water level detection switch 39 activates the electric circuit 40. When the water supply is stopped, the water level of the canned water 33 in the vertical water pipe 21 is set to the lower of the two levels, upper and lower. By operating the boiler for one more day at this water level and repeating the switching operation of the switch 40 using the automatic switching control of the electric circuit 40, the water level of the canned water 33 in the vertical water pipe 21 is automatically adjusted every other day. The upper limit water level can be changed automatically. Therefore, the water surface of the can water, which is the cause of corrosion, is present in two places, and the corrosion is dispersed. In addition, the width of scale adhesion becomes wider and it takes time for the scale to accumulate, and the scale becomes less likely to become thicker and overheating becomes less likely to occur. Due to these effects, once-through boiler 20
This will significantly extend the lifespan of the

Furthermore, the scale within the vertical water pipe 21 can be removed periodically by removing the water pipe header cap 26, and the life of the once-through boiler 20 can be extended to more than twice that of the conventional one.

[Effects of the Invention] The present invention disperses scale by automatically varying the water level in the water pipe of a once-through boiler using time as a parameter, suppresses scale thickening, and prevents the occurrence of overheated parts. This has the effect of significantly extending the life of once-through boilers by preventing local corrosion that tends to occur near the water surface.

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a front view of the main part cut away from the left half of an embodiment of the invention, Fig. 3 is a plan view of the main part, and Fig. 4 is a detailed view of the main part. be. 20...Once-through boiler, 21...Vertical water pipe, 2
2... Upper conduit body, 23... Lower conduit body, 27...
...Water supply control valve, 33...Canned water, 34...Water level gauge,
38, 39...Water supply stop water level detection switch, 40
...Electric circuit for boiler control, 44...Timer switch.

Claims (1)

[Scope of Claims] 1. A water pipe that converts internal canned water into steam by being heated; a first pipe body that communicates with the water pipe and collects steam from the water pipe; and a water pipe that communicates with the water pipe. A water pipe overheat corrosion prevention device for a once-through boiler, comprising: a second pipe body for supplying can water to the can; and a water level adjusting means for adjusting the water level of the can water to a predetermined water level; The system includes multiple water level detection units that detect different set water levels, a set water level switching unit that automatically switches the set water levels corresponding to the detection units using a timer using time as a parameter, and controls the amount of water supplied to the water pipes. 1. A water tube overheat corrosion prevention device for a once-through boiler, comprising a water level adjusting section that adjusts the water level of the can to a set water level set by the set water level switching section.