JPH0730886B2 - Boiler in thermal power plant-Leakage detector for water pipe - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a leakage detecting device for a boiler water pipe in a thermal power generation facility.

Conventional technology In general, thermal power generation uses a boiler to burn fuel, and its heat creates high-temperature, high-pressure steam, which is then sent to a turbine to rotate the turbine at high speed and electricity is produced by a generator directly connected to this turbine. Is.

In the boiler, a large number of boiler water pipes for generating high-temperature and high-pressure steam and sending it to the turbine are provided.
If there is a leak in the boiler water pipe, it may cause trouble in stable supply of electricity.

Therefore, conventionally, the presence or absence of leakage points in the boiler water pipe is confirmed by abnormal noise in the furnace during patrol inspection (for example, a rattling noise), or by increasing the supply flow rate or the make-up water flow rate. In addition, other things such as water leakage to the outside of the furnace, boiler residual pressure curve, O ₂ concentration in exhaust gas, and gaze from the sight glass are confirmed.

Problems to be Solved by the Invention This kind of thermal power generation facility is very large, and the amount of leakage is not very large in order to detect the presence or absence of leakage points in the boiler water pipe by the conventional confirmation method described above. I can't find it,
Early detection was difficult.

When the amount of leakage increases in this way, not only the efficiency of power generation decreases, but also the leakage spreads to the boiler water pipe in the vicinity of the leakage point, causing a serious accident.

Therefore, it is important to find the leak point of the boiler water pipe as early as possible, but in the past, there was no means to easily find it, and if a large amount of leak did not occur,
I couldn't find it. That is, if the leakage amount is small, the outflow noise is small, and an increase in the feed water flow rate or the makeup water flow rate cannot be distinguished from the flow rate change due to the power supply load fluctuation during normal operation. There was little leakage, and changes in the boiler residual pressure curve and changes in O ₂ concentration in the exhaust gas could not be clearly distinguished from normal conditions, which made it difficult to detect the presence or absence of leakage. Also, when looking through the viewing window, if the amount of leakage is small during operation, the vapor will disappear in a sublimated state,
It is difficult to detect, and there are cases where leakage points are present in the blind spot through the viewing window, and the interior of the furnace is dark during shutdown, so
However, there is a problem that it is difficult to surely detect from the viewing window.

In short, in this type of thermal power generation facility, if the amount of leakage of the boiler water pipe is small, it is very difficult to detect during operation, and even during stoppage, the amount of leakage is small, and
Detection was not possible if the leaked point was the blind spot of the viewing window.

Means for Solving the Problems The present invention has been proposed in view of the above-mentioned conventional problems,
The present invention is directed to, for example, activating the equipment every morning, stopping at night, and further, in order to speed up the start-up at the time of restarting operation, closing the entrance and exit of the boiler that is stopped (hereinafter,
Called hot banking. ] An operating system for reducing heat loss [hereinafter referred to as an intermittent operating system]. ]
It is a thermal power generation facility.

In the above-mentioned thermal power generation equipment, soot blowers for preventing soot from adhering to boiler water pipes, inspection windows for inspection, equipment such as TV cameras for monitoring the inside of the furnace, and ignition torches around the boiler body. Attached to these, during operation, the required air is diverged from the forced draft fan for combustion of the main burner as seal air or as combustion air to achieve the required functions and protect the equipment. ing.

However, at the time of stop, since the inlet and outlet of the boiler are closed and the forced draft fan is also stopped, air is not supplied to the seal air pipe and the combustion air pipe to the ignition torch.

The present invention has solved the conventional problems by paying attention to the above points, and its technical means is to reduce the heat loss by closing the inlet and outlet of the boiler that is stopped in order to accelerate the start-up when restarting the operation. In the intermittent operation type thermal power generation facility described above, the drain detection valve is branched and installed at one or both of the bottom of the seal air pipe and the bottom of the ignition torch combustion air pipe that are always open in the furnace.

Action While the intermittent operation type thermal power plant is stopped, in the hot banking state where the boiler inlet / outlet is closed, if there is any leakage in the boiler water pipe, a large amount of steam will be generated near the leakage point due to the high temperature inside the reactor. , The steam flows back to the seal air pipe that is open in the vicinity thereof and the combustion air pipe to the ignition torch, and is condensed. Then, the condensed air collects and accumulates as condensed water at the bottom of the seal air piping and the combustion air piping to the ignition torch.

If there is no leakage in the boiler water pipe, the furnace will not be filled with steam and will be in a dry state, so condensed steam will remain in the seal air pipe and the combustion air pipe to the ignition torch. There is no such thing.

Therefore, check the drain detection valve installed at the bottom of the seal air pipe or the bottom of the combustion air pipe to the ignition torch at an appropriate time during the stoppage of the equipment, or at the start-up inspection before restarting the operation. The presence or absence of leakage of the boiler water pipe can be reliably detected depending on the presence or absence of condensed water, even in a small amount or in the blind spot of the viewing window.

During operation of the equipment, the seal air pipe and the combustion air pipe to the ignition torch are branched and supplied with air from the forced draft fan, so that the combustion gas in the furnace does not flow backward, and Since the drain detection valve is closed, blast air does not leak from this part.

Example FIG. 1 is a schematic system diagram of a main part of a thermal power generation facility to which the device of the present invention is applied. In FIG. 1, (1) is a boiler main body, and inside is a boiler water pipe (2). Many boiler water pipes (2) are connected to a turbine (3), and a generator (4) is directly connected to the turbine (3). Combustion air is supplied to the boiler body (1) from the forced draft fan (5) via the air passage (6), and fuel is supplied from the tank (7) by the pump (8) via the main burner (9). It The exhaust gas after combustion passes through the flue (10) and then the chimney (1
Emitted from 1). Dampers (12) and (13) are installed at the entrance and exit of the boiler body (1), and these dampers (12) and (13) are opened in connection with the operation and closed when stopped during hot banking. It

A plurality of viewing windows (14) are installed at appropriate locations on the side wall of the boiler body (1), and the viewing windows (14) branch off from the middle of the air passage (6) of the forced draft fan (5). Seal air is diverged by the seal air pipe (15). An air volume adjusting valve (16) is provided in the middle of the seal air pipe (15), and a predetermined amount of air is diverted and supplied during operation. In addition, at the bottom of the seal air pipe (15), the drain detection valve (17)
Is installed in a branch.

FIG. 2 is a systematic diagram of the main part which is a slightly concrete form of FIG.
There are four ignition torches (1) around the boiler body (1).
8) are installed in multiple stages, and a combustion air pipe (19) is connected to the ignition torch (18). The combustion air pipe (19) is connected to the air passage (6) of the forced draft fan (5a) (5b).
It is branched from a) (6b) through the air volume control valves (16a) (16b). The seal air pipe (15) is branched from the middle of the steam combustion air pipe (19), and the seal air is branched and supplied to the soot blower, the sight glass, the furnace condition monitoring television camera, and the like. An ignition torch fan (20) is installed in the middle of the combustion air pipe (19) slightly downstream of the branch portion of the seal air pipe (15), and the installation position of this ignition torch fan (20) is the combustion air pipe. Since it is the lowest part in (19), drain detection valves (17a) and (17b) are installed in front of and behind this ignition torch fan (20). The lowest part of the seal air pipe (15) is near the branch part, and an air trap type drain detection valve (17c) is branch installed near this part. This air trap type drain detection valve (17c) is normally closed, and when water collects, it automatically opens with a float etc. to discharge water, and a drain receiver (21) is installed at the discharge end. To be done. An air volume adjusting valve (22) is installed on the inlet side of the ignition torch fan (20).

One of the forced draft fans (5a) and (5b) in FIG. 2 is operated and the other is spare, and the air is blown into the boiler main body (1) from the air duct (6a) or (6b), Exhaust gas from the main body (1) is led from the flue (10a) or (10b) to the chimney (11) via the electrostatic precipitators (23a) and (23b). In this case, the air preheaters (24a) (24b) for preheating the air by exchanging heat between the air supplied into the boiler body (1) and the exhaust gas are the wind ducts (6a) (6b) and the smoke duct ( Ten
It is installed between a) and (10b). In addition, in FIG. 2, a damper (25) is provided before and after the flues (10a) (10b) of the air preheaters (24a) (24b) and before and after the air passages (6a) (6b).
a) to (25h) are installed.

FIG. 3 shows a drain detection valve (17) that is branched and installed in the combustion air pipe (19) on the outlet side of the ignition torch fan (20) of FIG.
A water level gauge (17d) is installed in place of a), and other configurations are the same as those in FIG. 2, and therefore description thereof will be omitted.

Next, the procedure for detecting the presence / absence of leakage of the boiler water pipe (2) will be described.

If the amount of leakage of the boiler water pipe (2) is large, it can be easily found even during operation. That is, due to an image projected by a TV camera for monitoring the inside of the furnace, or due to an abnormal increase in the feed water flow rate to the boiler water pipe (2) or an abnormal increase in the make-up water flow rate, or an abnormality in the furnace during a patrol inspection. It is discovered by sound and even by an abnormal increase in the oxygen concentration of the exhaust gas.

However, if the amount of leakage is small, it is difficult to detect this during operation.

On the other hand, during shutdown, a large amount of leakage can be found during patrol inspection, etc. due to abnormal reduction of the boiler residual pressure curve, water leakage to the outside of the furnace, or abnormal noise inside the furnace, but it is the same as before. If it is a small amount, the sound is low and the inside of the furnace is dark, so it cannot be detected by sound or inspection through the viewing window.

However, if there is a small amount of leakage from the boiler water pipe (2), a large amount of steam is generated in the furnace, and this steam is generated in the combustion air pipe (19) and the seal air pipe (15) of the ignition torch (18). Backflow and condense. This condensed water will be collected and accumulated at the bottom of each pipe (19) (15),
Drain detection valve (17) (17)
a) (17b) (17c) or water gauge (17d).
Therefore, when the patrol inspector opens the drain detection valves (17), (17a), and (17b), it can be judged whether or not the drain will flow out, and the air trap type drain detection valve (17c) can determine the drain receiving (21). ) Can be judged by whether or not drain is accumulated, and by the water gauge (17d) it can be judged by whether or not water is accumulated.

The embodiment of FIGS. 2 and 3 exemplifies a case where the drain detection valve is installed near the ignition torch fan (20). But it's okay. Further, the drain detection valve is provided in either or both pipes. The specific type of the drain detection valve may be a general drain cock, an air trap, or a water gauge. In the case of the water level gauge, it goes without saying that a drain cock is also used.

Effect of the Invention According to the present invention, if there is a small amount of leakage in the boiler water pipe, it can be reliably detected in the hot banking state during stoppage, and early detection of the leakage location becomes possible,
It is possible to prevent major accidents. Moreover, since the means is very simple, it can be economically implemented at low cost and can contribute to the safe operation of this type of thermal power generation facility.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of main parts of a thermal power generation facility to which the device of the present invention is applied, and FIGS. 2 and 3 are main system diagrams showing different embodiments when the facility of FIG. 1 is slightly embodied. Is. (1) …… Boiler body, (2) …… Boiler water pipe,
(3) …… Turbine, (4) …… Generator, (5) …… Insertion fan, (6) …… Air passage, (7) …… Fuel tank,
(8) …… Fuel pump, (9) …… Main burner, (10)…
… Flue, (11) …… Chimney, (12) (13) …… Damper,
(14) …… Peep window, (15) …… Seal air piping, (17)
(17a) (17b) (17c) …… Drain detection valve, (17d) ……
Water level gauge, (18) …… Ignition torch, (19) …… Ignition torch Air piping for combustion.

Claims (1)

[Claims] 1. In an intermittent operation type thermal power plant in which the boiler inlet / outlet is stopped to reduce heat loss in order to speed up the start-up when restarting operation, the lowest part of the seal air pipe that is always open in the furnace And a leakage detection device for a boiler water pipe in a thermal power plant, wherein a drain detection valve is installed at one or both of the lowermost portions of the ignition torch combustion air pipe.