JPH0686927B2 - Soot blower - Google Patents

Abstract

The soot blower comprises a tube (1) provided with nozzles (2) and leading to a heat exchanger through an opening provided in a wall which is made tight by a box (7). The tube (1) and the box (7) are supplied with sweeping air and with retaining air which are produced, for each soot blower, by a compressor (16).

Description

The present invention relates to a soot blowing device for cleaning the heating surface of a heat exchanger constructed according to the preamble of claim 1.

In this type of sootblowing device, the combustion gas in the heat exchanger generated when burning solid, liquid or gaseous fuel communicates with the lance pipe of the sootblowing device by the heat exchanger. Therefore, there is a risk that it will flow into the lance pipe. This often results in damage to the lance pipe due to corrosion or contamination by the combustion gases, which are corrosive hot gases.

To overcome this drawback, a harmless gaseous cleaning medium, for example air, is introduced above the sootblower valve, the pressure of which is set slightly above the pressure on the combustion gas side in the heat exchanger. ing. By setting the pressure in this way, harmless cleaning gas flows through the lance pipe of the soot blowing device toward the heat exchanger, which prevents corrosive combustion gas from flowing into the nozzle. Has been done. If required, a blocking medium, for example air, is blown into the wall box surrounding the area of the inlet around the inlet of the lance pipe projecting into the heat exchanger for sealing.

In the case of heat exchangers, in particular power plant boilers provided with multiple sootblowing blowers, the cleaning air and the blocking air are taken from the central blower and distributed to the sootblowing devices. In this case, an expensive pipeline system is required. Due to the very low pressure levels of blowers used in conventional sootblowing devices, it is often necessary to set the cross sectional area of the conduit relatively large in order to keep friction losses low. In addition, since the lengths of the pipelines that extend to each soot-blowing blower are not the same, in order to disperse the required amount of air as uniformly as possible, it is necessary to disperse the required amount of air in spite of different friction losses. It is necessary to provide a special adjustment mechanism in front of the soot blowing device. Also, because of the thermal expansion of the heat exchanger and the displacement of the sootblowing device caused by the thermal expansion, the connection to the sootblowing device and / or the wall box must be designed flexibly.

Another drawback of the central air system is that air is often drawn through a conventional blower that is designed to shut down normally when the heat exchanger fails. As a result, undesired combustion gases enter the lance pipe of the sootblowing device or escape from the wall opening of the heat exchanger due to the chimney effect, which remains in the heat exchanger at high temperature for a relatively long time. Combustion gases may be released toward the interior.

In addition, the requirements that have been raised by many manufacturers and users of heat exchangers are that the amount of air introduced into each soot blowing device should be kept as low as possible and that even when pressure fluctuations occur on the combustion gas side. The amount of air should not exceed the maximum value.

Accordingly, it is an object of the present invention to simplify the previously known system for supplying the cleaning and blocking media to the sootblower.

In order to achieve the above object, a soot-blowing device characterized by the features described in the characterizing part of the first claim is proposed according to the present invention. Advantageous embodiments of the invention are described in claims 2 to 11
Please refer to the section.

According to the invention, a central blower and an expensive air distribution system can be dispensed with. This is because the cleaning air and the blocking air are supplied to each soot blowing device from a dedicated compressor.

The distribution lines of the compressor and the soot blower are designed to ensure that each soot blower always has the required amount of wash and shutoff air. Rough adjustments are made by the manufacturer.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings illustrating an embodiment of the present invention.

FIG. 1 is a side view of a soot blowing device according to the present invention. FIG. 2 is a detailed view of the Y portion of FIG. FIG. 3 is a detailed view of a Z portion of a soot blowing device constructed according to another embodiment of the present invention.

A long tube spiral soot blowing device is shown in the accompanying drawings. The present invention can be similarly applied to other types of soot blowing devices, except for the details described below.

The soot blower shown has a lance pipe 1,
A nozzle 2 is attached to the front end of the lance pipe 1. The lance pipe 1 is connected to a moving wagon 4 which is operated by a motor 3, and the moving wagon 4 can run together with the lance pipe 1 on a fixed support rail 5. Since the motor 3 can rotate the lance pipe 1 in addition to moving the lance pipe 1, the nozzle 2 moves in a spiral shape. The end point of the movement path of the lance pipe 1 is set by a fixed limit switch.

The lance pipe 1 can enter the heat exchanger through the inlet opening. The wall of the heat exchanger is indicated by the wall pipe 6. The inlet opening is surrounded by a wall box 7 to prevent leakage to the outside atmosphere. Even when the lance pipe 1 is retracted, the lance pipe 1 and the nozzle 2 remain in the wall box.

The movable lance pipe 1 encloses a fixed inner pipe 8 whose rear end is connected to a joint supplying a blowing medium, for example steam. The amount of the blowing medium can be adjusted by a valve 9 provided on the soot blowing device.

The inner tube 8 is equipped with a fitting 10 for passing a cleaning medium, for example air. The cleaning air joint 10 is arranged on the valve seat of the soot blower valve 9, that is, behind the soot blower valve 9 when viewed in the flow direction of the blowing medium.

Cleaning air is supplied to the lance pipe 1 through the cleaning air joint 10 and the inner pipe 8 and flows out from the nozzle 2. Cleaning air fittings
The check valve 12 is arranged in the washing air pipe line 11 extended to 10, and after the valve 9 is opened, the check valve 12 is installed so that the blowing medium does not get into the washing air pipe line 11. It is supposed to work.

The wall box 7 is equipped with a coupling medium 13 through which a blocking medium, for example air, is passed. The shutoff air joint 13 is connected via a flexible duct 14 to a shutoff air duct 15 extending above the soot blowing device. The pressures of the cleaning air and the blocking air are set higher than the gas pressure in the heat exchanger.

The cleaning air and the shut-off air are supplied from a device suitable for the soot-blowing device, which in the illustrated embodiment comprises a compressor 16 mounted on the soot-blowing device. The compressor 16 is assembled at the factory as one unit, connected to the soot blower. The electrical connection cable of the drive unit that drives the compressor 16 and the motor 3 of the moving part of the soot blowing unit is extended to the central terminal box, and it is safe to prevent electrical accidents in this terminal box. Equipment is in place.

As shown in FIGS. 1 and 2, the compressor
16 is disposed near the soot blowing device valve 9. An air line 17 is connected to the outlet of the compressor 16,
The air line 17 extends to a T-shaped joint. A shutoff air line 15 extending to the shutoff air fitting 13 of the wall box 7 and a wash air line 11 extending to the wash air fitting 10 branch off from the T-shaped joint 18. Air line 17
A safety valve 19 is provided on the way, and the operating pressure of the safety valve 19 is set according to the discharge pressure of the compressor 16. The compressor 16 is preferably designed to have a supply capacity that is independent of the level of back pressure on the combustion gas side. It is possible to use a compressor that operates according to the push-in principle, such as a piston type compressor or a rotary piston type compressor. Use a bypass compressor that can operate regardless of back pressure in the pressure range of 0.99 to 1.02 bar associated with sootblowing devices, but whose procurement costs are well below the types of compressors listed above. Is particularly advantageous. By designing the compressor in this way, the back pressure on the combustion gas side is
Below the set pressure of 16, the supply capacity does not increase or only increases slightly. The use of such a compressor is distinctly advantageous compared to previously known central pneumatic systems whose operating point is largely dependent on the back pressure of its orbit.

Another feature of the compressors listed above, as compared to radial blowers, is that they are able to operate against relatively high back pressures and thus overcome the high frictional resistance in the sootblowing device. Therefore, Lance Pipe 1
If a soot-blowing device of a type such as the long-tube spiral-type soot-blowing device shown in which the nozzle 2 provided at the end of the soot is held stationary in the wall box 7 is used, The air introduced therein can be used as washing air and also as blocking air. If the soot blower configured as described above is used, the air flowing out from the nozzle 2 is prevented from flowing into the soot blower while the combustion gas is prevented from leaking from the wall surface of the heat exchanger. It also works to prevent it. Therefore, such a configuration mode provides a flexible conduit required for the displacement movement of the wall of the heat exchanger.
This is advantageous because you can dispense with 14. However, this configuration mode can be selected only when the overpressure on the combustion gas side is low and it is not necessary to supply the cutoff air while the soot blowing device is operating. That is, the check valve 12 is closed while the soot blowing device is operating, and the compressor 16 is energized or the safety valve 19 is blown out. However, when the overpressure is comparatively high, as shown in the drawing, separate washing air joint 10 and shut-off air joint 13 must be prepared.

In the case of the embodiment shown in FIG. 3, the compressor 16
Is directly attached to the wall box 7.

In this embodiment, the shutoff air fitting 13 is the wall box 7
Is connected and fixed. Also in the case of this embodiment, the air blown into the wall box 7 can be used as the blocking air and at the same time as the cleaning air, so that the combustion gas escapes from the heat exchanger into the atmosphere. There is no risk of it flowing into the soot-blowing blower.

When the shut-off air and the cleaning air must be supplied separately, as shown in FIG. 3, a T-shaped joint 18 having a branch communicating with the cleaning air line 15 is provided in the middle of the air line 17. Must be provided. When the soot blowing device is not in operation, that is, when the soot blowing device valve 9 is closed, in the case of a soot blowing device of the type in which the nozzle 2 of the blowout pipe projects into the heat exchanger, It is necessary to supply the cleaning air and the blocking air separately. For a multi-nozzle sootblower of this kind, which is always located in the gas stream, a supply of washing air and shut-off air according to either of the embodiments shown in FIGS. You have to choose a method.

Soot blower valve 9 open and check valve 12 closed While the soot blower is in use the compressor
The compressor 16 is controlled so that 16 operates continuously. Should overpressure occur, the safety valve 19 is released to release the overpressure. In the case of a soot-blowing device that is operated using only cleaning air, when operating the soot-blowing device,
It is preferable to perform control so as to turn on the power to the compressor 16. In this case, the compressor
The 16 electrical drive on / off pulses are sensed by a sootblower controller protection system controlled by a sootblower limit switch.

Claims (11)

[Claims] 1. A soot blowing device comprises a lance pipe (1) which extends through a wall of a heat exchanger and which has a wall around the penetration. A box (7) is provided for sealing, a nozzle (2) is provided at the front end of the lance pipe (1), and a soot blower valve (9) is blown at the rear end to blow off the medium. Connected to the supply section of
The lance pipe (1) was provided with a washing medium joint (10), and the wall box (7) was provided with a shutoff medium joint (13) and extended to the washing medium joint (10). After the soot blowing device valve (9) is opened in the cleaning medium pipe (11), a check valve (12) for preventing the blowing medium from flowing through the cleaning medium pipe (11) is provided. A soot-blowing device for cleaning a heating surface of a heat exchanger configured to be provided, characterized in that the soot-blowing device comprises a dedicated device for supplying and spraying a cleaning medium and a blocking medium. Blowing device. 2. The soot-blowing device according to claim 1, characterized in that the device dedicated to the first half period comprises a compressor (16). 3. A soot blowing device according to claim 2, characterized in that the compressor (16) is configured as a bypass compressor. 4. A safety valve (19) is provided between the compressor (16) and the joints (10, 13) for the cleaning medium and the blocking medium, and the safety valve (19) adjusts the set pressure of the compressor (16). The soot blowing device according to any one of claims 1 to 3, wherein the soot blowing device is adjusted together. 5. The compressor according to claim 1, wherein the compressor (16) is attached to the soot blowing device and cooperates with the soot blowing device to form one independent unit. The soot-blowing device according to any one of items 4 to 4. 6. A soot blowing device according to claim 5, characterized in that the compressor (16) is arranged in the vicinity of the soot blowing device valve (9). 7. A soot blowing device according to claim 6, characterized in that the cleaning medium and the blocking medium are introduced on the valve seat of the exclusively soot blowing device valve (9). . 8. A soot blowing device according to claim 5, wherein the compressor (16) is arranged in the vicinity of the wall box 7. 9. The soot-blowing device according to claim 8, characterized in that the blocking medium and the washing medium are introduced exclusively around the wall box (7). 10. The electrical connection cable for connecting the soot blowing device and the compressor (16) is extended to the center terminal box, and claims 1 to 9 are claimed. The soot blowing device according to any one of 1. 11. The compressor (16) is energized while the soot blowing device is in use, and the compressor (16) is controlled by an on / off pulse of a limit switch of the soot blowing device. The soot blowing device according to any one of claims 1 to 10 characterized in that.