WO1985002673A1

WO1985002673A1 - Soot blower

Info

Publication number: WO1985002673A1
Application number: PCT/EP1984/000390
Authority: WO
Inventors: Karl Albers; Hans Schwade
Original assignee: Bergemann Gmbh
Priority date: 1983-12-06
Filing date: 1984-12-05
Publication date: 1985-06-20
Also published as: IN163540B; CA1259002A; ATE23630T1; DE3343992C2; EP0148997A1; JPS61500628A; DE3343992A1; JPH0686927B2; DE3461338D1; EP0148997B1

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

R u ß bläser

The invention relates to a soot blower for cleaning heating surfaces in a heat exchanger with the features of the preamble of claim 1.

In the case of these sootblowers, the smoke gases in the heat exchanger, which are produced when solid, liquid or gaseous fuels are combusted, are connected to the lance tube of the sootblower via the nozzles and can penetrate into it. The mostly aggressive and hot gases cause damage due to corrosion or pollution.

To eliminate these disadvantages, a harmless, gaseous flushing medium, for example air, is introduced above the soot blower valve, the pressure of which is somewhat higher than the pressure in the heat exchanger on the flue gas side. This causes a flow of the harmless flushing medium through the lance tube of the soot blower in the direction of the heat exchanger, which avoids the penetration of the aggressive smoke gases at the nozzles. Also for the purpose of sealing, a barrier medium, for example air, is blown into the wall box surrounding the entry point at the entry of the lance tube into the heat exchanger.

The purge air and sealing air are taken from a central blower in heat exchangers, especially in power plants that are equipped with a large number of sootblowers, and distributed to the individual sootblowers. A complex pipeline system is required for this. Because of the mostly low pressure level of the central blowers used, relatively large line cross sections are often required in order to keep the friction losses low. Furthermore, a separate control element is required in front of each soot blower in order to ensure that the required air volumes are distributed as evenly as possible to ensure the different friction losses due to the different pipe lengths to the individual soot blowers. Finally, the connections on the sootblower valve and / or on the wall box must be made flexible due to the thermal expansion of the heat exchanger and the movement of the sootblower caused thereby.

Another disadvantage of the central air system is that the air is often taken from an existing fan, which is normally taken out of operation when the heat exchanger is switched off. The consequence of this is that the chimney effect within the still hot heat exchanger drives the undesired smoke gases into the lance tube of the sootblower or out of the wall opening of the heat exchanger to the outside.

A procedural requirement of many manufacturers and operators of heat exchangers is, moreover, that the amount of air introduced per sootblower should remain as small as possible and should not exceed a maximum value even in the case of frequently occurring pressure fluctuations on the flue gas side.

The invention has for its object to simplify the known system for supplying the soot blower with flushing and blocking medium.

This object is achieved by the features of claim 1, advantageous embodiments of the invention are characterized in the subclaims.

It is achieved by the invention that the central blower and the complex air distribution system can be dispensed with, since the purge and sealing air can be generated on each soot blower by a separate compressor. This compressor and the distribution pipes on the soot blower are designed so that each soot blower always receives the required amount of purge air and sealing air. The necessary rough setting can be made at the manufacturer.

Several embodiments of the invention are shown in the drawing and are explained in more detail below.

Show it:

1 is a side view of a soot blower according to the invention,

Fig. 2 shows the detail Y of FIG. 1 and

Fig. 3 shows the detail Z of FIG. 1 for another embodiment of the invention.

In the drawing, a long-tube screwblack blower is shown. Except for the details mentioned later, the invention is equally applicable to other types of soot blower.

The soot blower shown has a lance tube 1 which is provided with nozzles 2 at its front end. The lance tube 1 is connected to a gear carriage 4 which is driven by a motor 3 and which can be moved together with the lance tube 1 on a stationary mounting rail 5. The motor 3 also sets the lance tube 1 in a rotational movement, so that the nozzles 2 perform a helical movement overall. The end points of the travel path of the lance tube 1 are each determined by a fixed limit switch. The lance tube 1 can be moved through an inlet opening into a heat exchanger, the wall of which is indicated by a wall tube 6. The inlet opening is surrounded by a wall box 7 for sealing against the outside atmosphere. This is in the retracted state

Lance tube 1 with the nozzles 2 inside the wall box 7.

The displaceable lance tube 1 surrounds a stationary inner tube 8, the rear end of which has a connection for a blowing medium, for example steam. The amount of the blowing medium is regulated via a sootblower valve 9 arranged on the sootblower.

The inner tube 8 is provided with a connection 10 for a flushing medium, for example air. The purge air connection 10 is above the valve seat of the soot blower valve 9, d. H. arranged in the flow direction of the blowing medium behind the soot blower valve 9, via the purge air connection 10 and the inner tube 8, the lance tube 1 is supplied with purge air which emerges from the nozzles 2. A check valve 12 is arranged in a scavenging air line 11 leading to the scavenging air connection 10 and is set such that the blowing medium cannot penetrate through the scavenging air line 11 after the soot blower valve 9 has been opened.

The wall box 7 is provided with a connection 13 for a blocking medium, for example air. The sealing air connection 13 is connected via a flexible line 14 to a sealing air line 15 laid on the soot blower. The pressure of the purge air and the sealing air is above the gas pressure prevailing in the heat exchanger.

The purge air and the sealing air are generated by a device which is specific to each soot blower and which is formed by a compressor 16 which is attached to the soot blower. The compressor 16 is connected to the soot blower in the workshop into one unit. In doing so, too the electrical connection cables for driving the compressor 16 and for the motor 3 of the soot blower drive are routed to a central terminal box and are electrically secured there.

• 5

According to FIGS. 1 and 2, the compressor 16 is arranged in the vicinity of the soot blower valve 9; An air line 17 is connected to the outlet of the compressor 16, which leads to a knee stitia8. The sealing air line 15 branches off from the elbow 18 0 to the sealing air connection 13 on the wall box 7 and the purge air line 11 branches off to the purge air connection 10. A safety valve 19 is provided in the air line 17, the response pressure of which corresponds to the design pressure of the compressor 16. The compressor 5 is preferably an embodiment which has a delivery volume that is largely independent of the level of the counter gas pressure on the flue gas side. Compressors operating according to the displacement principle, such as piston and rotary piston compressors, can be used. The use of a side channel compressor, which can work largely independently of the back pressure in the pressure range of 0.99 to 1.02 bar which is of interest to the sweet-tooth blowers, is particularly advantageous, but is considerably less than the previously mentioned compressor types with regard to its acquisition costs . With these compressor designs, it can be ensured that the delivery volume does not increase or only increases insignificantly, even if the counterpressure on the flue gas side is lower than the design point of the compressor 16 see whose operating point is very much dependent on the prevailing back pressure. Another advantage of the above-mentioned compressors compared to radial blowers is the possibility of being able to work against relatively high back pressures, so that greater frictional resistances can be overcome within the soot blower. This results in the possibility of using the air introduced into the soot blowers both as purge air and as sealing air if it is a soot blower type such as the long-tube screw-type soot blower shown, in which the nozzles 2 at the end of the lance tube 1 in Stand retirement within wall box 7. Thus, the air flowing out of the nozzles 2 ensures, on the one hand, that no smoke gases penetrate into the sootblower and, on the other hand, seals the heat exchanger wall. This means that the sealing air connection 13 on the wall box 7 can be omitted. This solution is so advantageous because the flexible lines 14 required due to the movement of the heat exchanger wall can be omitted. However, this design can only be selected if the smoke-side overpressure is low, so that it can be accepted that no sealing air is emitted during the blowing operation of the soot blower. During this operating time, the check valve 12 is in fact closed and the compressor 16 is switched off or blows off via the safety valve 19. At higher overpressures, however, separate purge air connections 10 and sealing air connections 13 must be provided, as shown.

In the embodiment shown in FIG. 3, the compressor 16 is arranged directly on the wall box 7. The sealing air connection 13 is rigidly connected to the wall box 7. The air blown into the wall box 7 can simultaneously serve as sealing air and purge air and ensure that the flue gases cannot escape from the heat exchanger into the open or can penetrate into the soot blowers. If a separate supply of sealing air and purge air has to be provided, the knee 18 must be provided in the air line 17 with a branch to the purge air line 15, as shown in FIG. 3. A separate purge air and sealing air supply is also necessary in those soot blower types in which the nozzles 2 of the blowpipe remain in the heat exchanger even when the sootblower is not in operation, ie the sootblower valve 9 is closed. For such multi-nozzle soot blowers which remain permanently in the gas stream, a task of the purge air and the sealing air can be selected according to each of the embodiments shown in FIGS. 2 and 3.

The control of the compressor 16 can be operated in such a way that the compressor 16 runs continuously, that is to say also during the soot blower operation with the soot blower valve 9 open and the check valve 12 closed. Any overpressure that builds up is discharged via the safety valve 19. In the case of soot blowers which are only supplied with purge air, the control is preferably carried out in such a way that the compressor 16 is turned off when the soot blower is in operation. The switch-on and switch-off pulses for the electrical drive of the compressor 16 are picked up by the contactors of the sootblower control, which are controlled by the limit switches of the sootblower.

Claims

PATENT CLAIMS:

1. Sootblower for cleaning heating surfaces in a heat exchanger, the sootblower having a lance tube (1) which is passed through the wall of the heat exchanger and is sealed at the passage by a wall box (7), wherein the lance tube (1) is provided with nozzles (2) at its front end and is connected at its rear end via a soot blower valve (9) to a supply for a blowing medium, the lance tube (1) having a connection (10) for a flushing medium or the wall box (7) with a connection

(13) is provided for a barrier medium and a check valve (12) is provided between the soot blower valve (9) and the flushing medium connection (10), characterized in that the soot blower has its own device for producing and distributing the flushing medium and the barrier medium is provided.

2. Soot blower according to claim 1, characterized in that the device consists of a compressor (16).

3. Soot blower according to claim 2, characterized in that the compressor (16) is designed as a side channel compressor.

4. soot blower according to one or more of claims 1 to 3, characterized gekennzelehnet that between the compressor (16) and the connections (10, 13) for flushing medium and barrier medium, a secure he its valve (19) is provided, which on the Design pressure of the compressor (16) is set.

5. soot blower according to one or several of claims 1 to 4, characterized in that the compressor (16) is attached to the soot blower and forms an independent unit with the latter.

6. soot blower according to claim 5, characterized g e k e n n ¬ z e i c h n e t that the compressor (16) is arranged in the vicinity of the soot blower valve (9).

7. soot blower according to claim .6, characterized g e k e ¬ z e i c h n e t that the initiation of the flushing and locking medium occurs exclusively above the seat of the soot blower valve (9).

8. soot blower according to claim 5, characterized g e k e n n ¬ z e i c h n e t that the compressor (16) in the vicinity of the wall box (7) is arranged.

9. soot blower according to claim 8, characterized g e k e n n - z e i c h n e t that the initiation of the blocking and

Flushing medium only on the wall box (7).

10. sootblower according to one or more of the claims

1 to 9, characterized by the fact that the electrical connection cables for the connection of the

Soot blower and the compressor (16) are guided to a central terminal box.

11. sootblower according to one or more of claims 1 to 10, characterized in that the compressor (16) is switched off during sootblower operation and is controlled by the switch-on and switch-off pulses of the sootblower limit switch.