DD235711A1 - ARRANGEMENT FOR AVOIDING DUST STORAGE IN CROSS-LINKED LINES BETWEEN CARBON MILLS - Google Patents

Abstract

The invention relates to an arrangement for preventing dust deposits in a pipe, wherein the deposits in the promotion of a coal dust mixture behind leaking closure devices arise. This is achieved in that, according to the invention, the conduit has closure means connected to the atmosphere, which are arranged behind the gate valve. Fig. 1

Description

Title of the invention

Arrangement for preventing dust deposits in a pipe

Field of application of the invention

The invention relates to an arrangement for avoiding caused by a conveyed on leaking closure devices pulverized coal feed gas mixture dust deposits in conduits, in particular cross-connections between the mill systems.

Characteristic of the known technical solutions

For starting a steam generator, it is known to promote the pulverized coal conveying gas mixture from a pulverized coal mill of a steam boiler in operation via a cross connection in a pulverized coal mill of the steam boiler to be approached (DD-PS 213 744).

When operating cross-connection can not be deposited due to high conveying speeds coal rod. If the cross-connection is out of operation, then a gas flow can occur in the lines due to leaks in the valves or valves and / or the pressure differences acting on the slides, which entrains coal dust which settles in the pipes.

IVeiterhin can decommissioning of the cross-connection and / or the tiühlen still in the cross-connection conveying gas-dust mixture not be removed, the feed gas flow come to a standstill and the residual dust contained therein deposited.

The same effects occur when a part of the conveying gas-dust mixture sucked from a Mysteries on a parallel flow through branch lines, the dust separated and the clean gas returned to the mill system or any other flue gas-carrying system is fed »There are hazards of systems engineering and Persons by spontaneous combustion of coal dust and / or deflagration, in particular when restarting and Staubaufwirbelungen possibly glowing particles given.

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A disadvantage of the commissioning of cross connections between mills is the necessary simultaneous opening of the gate valve, otherwise strong negative pressure or overpressure act on slide and cross-connection. For this reason, until now the mill cross connection had to be opened when the adjacent mill systems were out of operation, and then both mills were switched on at the same time.

When coal pulverizer units are put into operation, hot carrier gas-dust mixture is immediately conveyed into the system, which may still have dust deposits, thus creating hazards (deflagration, raising dust, etc.).

To avoid dust deposits in pulverized coal plants, it is known to design the flaps and slide so that a maximum tightness is to be achieved. It is also known to apply flaps and slide with sealing air, so that a passage of pulverized coal conveying gas mixture should be impossible.

Since these measures have not led to the success, it is known to operate pulverized coal plants with an inerting gas (DE-OS 2849432). However, this procedure requires considerable expenditure on plant and plant management technology. Likewise, it has been proposed to connect dust deposits in connecting lines by incorporating a shunt line (DD-PS, WP G 23 U / 265 667) or to promote the pulverized coal with a blower in circulation through the separator and deposit (DD-PS WP F 23 U / 265 663).

However, these solutions are only applicable when dust deposits must be removed from a connected in parallel to a Mysterious system pipe system with associated fans and separators. In this case, the output and input of the pulverized coal pipe system in the same mill system · The proposed in this solution complex system technology, short-circuit the coal dust pipe system via cross-connections, requires a complex construction with additional gate valves, which must also be cleaned regularly from dust -

Object of the invention

The aim of the invention is to operate the existing equipment despite leaks in the slide, to take in and out of 3betrieb and keep dust-free at a standstill.

Explanation of the essence of the invention

The invention has for its object to simplify the switching sequence in commissioning and decommissioning of Hühlen transverse connections and / or pulverized coal separation plants to remove dust deposits after gate valves or to prevent their disfigurement.

This is achieved in that according to the invention, the conduit having the atmosphere associated closure means which are arranged behind the gate valve.

embodiment

In one embodiment, the invention is explained in detail. The drawing shows in principle the arrangement of the closure devices in the cross-connection between two pulverized coal mills of different steam boilers or in the pulverized coal branch line to a dust-driven, not shown, dust collector (FIG. 1).

The pulverized coal mill 1 is assigned to the steam boiler 1 a and the pulverized coal mill 9 to the steam boiler 1 b. The pulverized coal mills 1; 9 have the coal chute 16; 17 with flue gas valves 21; 22, the classifier 2; 10 and the pulverized coal duct 3; 13 with gate valves 12, 20 on. The coal dust channel 3 with gate valve 12 is connected via flap 19, gate valve 4 with cross-connection 7 and gate valve 8 with the suction side of the pulverized coal mill 9.

After gate valve 4 are in the cross-connection 7, the flaps 5; 6 arranged and connected through openings with the atmosphere The drive of the gate valve 4 and the drive of the flap are locked against each other and acted upon by signal 13

Below the flap 6, the funnel line 14 is arranged, which opens into the flushing channel 15.

In the cross-connection 7, the sprayer 11 is involved «The flaps 5; 6 are then formed as a cold air flap when the cross connection 7 opens into the cold air pipe of the pulverized coal mill 9.

In the arrangement of a dust collector fan system after gate valve 4 is followed by the coal dust line 23, which 'opens into a dust trap, not shown, from which the Rsingas sucked off via a fan, not shown, and the clean gas line 24, the gate valve 25 opens into the coal dust channel 3. Here, immediately behind the gate valve 25 on the underside of the clean gas channel 24, a funnel-shaped opening 26 is arranged over the entire cross-section and can be closed by a slide 27. Gate valve 25 and slide 27 are locked against each other via drives and acted upon by the signal 28.

The mode of action is the following:

Fig. 1 with cross-connection between adjacent mill systems is in operating cross-connection, mill 1; 9, closed gate valves 12; 22, open gate valves 4; 8th; 20; 21, opened flap 19 and closed flaps 5; 6 coal dust gas mixture from mill 1 to mill 9 promoted. When decommissioning the cross connection is switched as follows.

At the same time, the slide 12 and the flaps 5, 6 are opened, and the slide 4 and the flap 19 are closed. Thus, during the closing and opening operation of the slide and flaps the transport of conveying gas Staüb mixture from the mill 1 is partially secured in the coal dust channel 3 and in the cross-connection 7 to the mill 9. At the same time is decreasing, opening cross-section of the closing slide 4, the proportion of conveying gas-dust mixture through the cross-connection 7 in favor of an increase of sucked Uragebungsluft on the increasing opening cross-section of the flaps 5; 6 go back to O % ·

At the end of the closing process, pure ambient air is drawn in as cold air and the cross-connection is blown dust-free.

After a predetermined operating time for releasing the slide, the slide 22 can be opened, hot flue gas and lignite coal through the coal chute 17 are fed to the mill 9 · This is done regardless of the degree of opening of the gate valve 8. In compliance with the permissible gas temperature range after mill 9 gate valve S is closed. In continuous operation of the mills 1; 9 without cross-connection will be in the coal dust channel 3 before the gate valve 4, depending on the negative pressure of the combustion chamber, a pressure p. from Z. 8 - 20 to + 20 mm'.VS and in _<o hlefallschacht 17 prior to grinder 9 a negative pressure P of ₈ - Set 100 mm WS - 150. By the open flap 6, the flap 5 may optionally be closed, so between cross-connection 7 and the environment a free cross-section will be present and in this at the gate valves 4; 8 Set the atmospheric pressure ρ = - 0 mm WS. This has the consequence that compared to the differential pressure Δ P ₄ above the gate valve 4 in the absence of free opening at / \ Ρλ - Pa ~ Pq ^ 3-30 mm WS (the maximum value is at tight flap 4 and heavily leaky or slightly open flap 8) now ι over the flap AP ₄ = P ₄ - P ₀ = - 2 to + 20 mm WS and over the flap 8 APg ⁼ Pg ~ P ₀ ⁼ ~ ¹⁵ ° to - 100 mm VVS sets ,

With the sinking AP ₄ , the gas exchange and thus also a dust discharge via the flap is greatly reduced or partially completely prevented. If nevertheless smallest amounts of dust leak on the leaking gate valve 4, these can not be deposited in front of the gate valve, as they fall immediately through the open flap 6 into the open or in the funnel 14 and from there on the flushing channel 15 is flushed by the in the cross-connection 'projecting flap 5 is also possibly the dust-laden gas stream over the free cross-section in the funnel line or, discharged into the open, so that residual dust can not be routed into the cross-connection 7.

In special cases, the flap 6 can be designed so that it closes the entire channel cross-section of the cross-connection 7 in the open state and thus completely excludes dust entry into the cross-connection. To further ensure the dust-free connection of the cross-connection can be opened periodically or before using the gate valve something and sucked cold air over the flap 5 and / and thus residual dust behind gate valve 5 and are sucked out of the cross connection. Since the system can also be used as a cold air supply for controlling the maximum gas temperature according to the mill, the generation of dust-free space inevitably occurs in this type of operation. For emergencies, a spray device 11 is arranged, moistened with which dust deposits or i in the mill 9 flushed.

The commissioning of the cross connection in operation! located steam generators is possible without locking the slide and flaps of adjacent steam generator. In operating mills 1; 9 is switched as follows: decommissioning j the raw coal feed the mill 9, while maintaining the permissible gas temperature mill 9, gradually opening the slide 8 and closing the slide 22, closing the slide 5, open the slide 4, simultaneous closing of the slide 5; 12 and open the flap 19. In this case, a continuous gas flow over the cross-connection of initially 100 % cold air up to 100 % conveying gas-dust mixture from mill 1 in mill 9 is secured. But if z, B. the mill 1 in operation and the steam generator of the mill 9 should be approached cold, so the mill with the cross connection can also be connected without difficulty as follows: open the flap 5; 6 and the slide 8, closing the slide 22, approaching the mill 9, which via the flaps 5; 6 draws in cold air and conveys it via the coal dust channel 18 to the 1-high burner. Oetzt can at any time at the same time closed the flap 6 and the slide 4 are opened.

Thus, a partial flow Förderfas dust mixture from the mill is sucked together with cold air through the flap 5 through the cross-connection 7 to the mill, ground there again and blown on the main burner. Thereafter, or at the same time, if the dust mixture is to be enriched in the coal dust channel 18, the flap 19 and the slide 12 close the coal dust channel 3 and the flap 5 are closed, so that the entire conveying gas-dust mixture to the mill. 9 is encouraged.

In a further solution, it is also possible to reduce the main burner power at an early stage of the startup of the steam generator of mill 9 in order to prevent too rapid heating of the combustion chamber with the consequential damage. Oies is achieved by shutting off parts of the main burner to the coal dust channel 18 via slides or flaps. Thereby the resulting increased flow resistance leads to a throttling of the through the mills 1; 9 funded delivery volume with the necessary lower raw coal tasks through chute 16, but a simultaneous accumulation of dust in the conveying gas, in particular the fine grain content, with the associated improved ignition conditions at the burner.

The possibilities of cold air intake via the flaps 5; δ also counteract problems of accidental circuit and mill failure.

Must ζ. B. the mill 9 go out of operation, it can be closed at the same time open the flap 5 and / or 6 during their expiration and the cold air supply to cool the mill 9 is secured. In this case, the coal dust channel 3 can be opened again beforehand via the flap 19 and the slide 12 and the mill 1 need not be taken out of operation.

If, on the other hand, the mill 1 fails due to damage, the cross connection can be separated by following the same switching action.

Likewise, the mills 1; 9 disconnected via the cross-connection without any problems, if the first z. 3. the flap 5 is opened. As a result, the delivery volume is reduced at the expense of cold air intake.

The air intake via the flap 5 catches any pressure differences of both mill systems resulting from further switching actions, since more or less cold air is sucked in, depending on the pressure setting in the cross connection. Thus, without separation of the cross-connection z. 3. open as the first slide 22 and also small amounts of raw coal on the chute 17 are added and only then the coal dust channel 3 open and flap 19 and slide 4 are closed and to a dependent of the permissible gas temperature after mill 9 time aer Slider closed and the flap 6 are opened.

Commissioning, which was not described here, can be done in the reverse order of the described shutdown and vice versa, the not described further possibilities of Aubetriebbetriebnahme the cross connections.

Likewise, effects and benefits of the flaps 5; 6 and the slide 27 are described or derived:

Be out of service Staubabscheide system and closed gate valves 4; 25 and in-operation mill 1 is a pressure difference between the areas of the gate valve 4 through the druckverlustbehalftete promotion in the coal dust duct 3; 25 be present. The higher pressure before gate valve 4 and lower pressure before gate valve leads when closing flaps 5; 6 and slide 27 and leaking gate valves 4; 25 to a low gas flow from the coal dust channel 3 via gate valve 4, coal dust line 23, the separator, not shown, and the fan, clean gas line 24 and gate valve 25 back into the coal dust channel. 3

With this low gas flow fine coal dust is carried along, which settles mainly behind the gate valve 4 and on Krümmernvorsprüngen and cross-sectional extensions in the fan and separator and can lead to glowing fires or when starting up to deflagration.

But if the mill 1 out of operation, so is due to the greater negative pressure in the combustion chamber in height at the level of vacuum suction in the main burner level a small gas flow from the main burner on coal dust duct 3 in the mill 1 and chute 16 done so that analogous to the previously described, now in the reverse direction a parallel low gas flow over leaking gate valve 25, clean gas line 24, fan, separator, coal dust line 23 and leaking gate valve 4 in the coal dust channel 3 and thereby to dust accumulation predominantly behind slide 25; 4 can lead.

In both cases, by opening slide 27 and flap 6 or 5 behind the gate valves 25; 4 the ambient pressure is present. This will be

- A gas flow with eventual dust transport between the gate valves 4; 25 via the lines 23; 24 prevents separator and fan due to lack of pressure difference,

- A dust deposit behind the gate valves 4; 25 prevents

- At yet by any overpressure in the pulverized coal pipe 3 resulting dust on the gate valves 4; 25 of these via the funnel-shaped opening 26 and the flap 6 to the outside or via the funnel lines 30; 14 fall into the flushing channel and be rinsed there.

Another advantage arises according to the invention when starting or decommissioning of the separator-fan system. Thus, the system without Treibgas-dust mixture can be angefahrer such that sucked open with open slide 27 and open flaps 5 and / or 6 cold air and blown out on the slide 27

is thereby cooled and blown out any dust deposits or glimmering particles (this may be necessary even at standstill of the system from safety requirements to verify the absence of dust) · Thereafter, parallel to or successively the gate valve 25; 4 (at the previous closing of the flap 6) is opened and 27 subsequent conveying gas-dust mixture in the separation plant and clean gas via the fan the coal dust channel 3 are fed again in subsequent or parallel closing of the flap 5 and slide. The flaps 13; 29 so far opened that a sufficiently large parallel flow of conveying gas-dust mixture in the coal dust channel 3 is promoted with open gate valve 12. If, in contrast, the pulverized coal channel 3 is designed as a subchannel, which conveys only a partial flow from the mill, this j can be completely shut off when the pulverized coal channel region 3 between the sliders 4; 25 on the fully open flaps 19; 29 be promoted via the separator-fan system.

The decommissioning of the separation system can be done without parallel connection, the slide and flaps such that after partial closing of the flaps 29; 19, the gate valve 4 is closed and the flap 13 is opened in parallel via the signal 13. Thus, 4 cold air is sucked through flap 5 with decreasing conveying gas-dust flow during the slipping of gate valve.

After closing the gate valve 4, the flap 6 and the slide 27 can be opened at a time dependent on the Betriebsregirae and then or parallel to the gate valve 25 and the flaps 19; 29 closed.

Even with this driving a dust-free separation of the separator Lüf-system is guaranteed and the fan can be taken out of service.

Depending on the degree of automation, this can be done via signal 13; 28 the order of the circuits are controlled or regulated »

The flap system in front of gate valves is also useful in Staubabscheide systems without fan operation, the clean gas line 24 in any vacuum region of the steam generator, z. 8. is integrated in the smoke channel after economizer or air preheater or in the chute 16 before mill 1 ·

Also in this case, by the flaps 5 or / and 6 and / or the slider 27 or eirebeliebige combination of openings to the environment behind the closed gate valves 4 and / or 25 or these replacement butterfly valves a low conveying gas flow through the separation or other conveyor systems and / or coal dust deposits behind the shut-off devices are avoided.

Furthermore, it is possible to realize the systems of cross-connection 7 of mill 1 to mill 9 and in the reverse direction via a common cross-connection and / or cross-connection 7 and separation systems with coal dust line 23 due to the improved arrival and departure possibilities and dust-free and to combine clean gas line 24 and / or for both common confluence with gate valves 4 and / or 8 and / or 25 in Kohlenstaubkanäle 3 or mills to realize, so as to save further Absperr * and control devices. Of course, the branch lines 7; 23; 24 also open directly into mills or burner systems, if the existing plant technology can guarantee a better function.

The following advantages are achieved:

1. Carbon dust ducts and / or separation systems can be kept dust-free or dust-free.

2. Elaborate dustproof shut-off devices can be omitted.

3. Elaborate controiluken and Dust clearance inspection can be omitted.

4. The systems can be switched on or off after any operating or decommissioning times.

5. There is no risk to personnel or deflagration.

6. The systems can be dried out by continuous admission of air and dried with cold air.

7. Locking conditions and BMSR costs are reduced

8. Pre-operation or individual switching is safe

possible, j

9. When switching the cross-connection, no interlock between the valves and valves of the mills and cross-connection of adjacent steam generators is necessary.

Claims (3)

invention claim 1. Arrangement for avoiding dust deposits in a pipe, in particular in a cross-connection between pulverized coal mills, wherein the line is integrated via a flap and / or a slider in a coal dust channel, characterized in that the line has associated with the atmosphere closure devices behind the gate valve are arranged. 2. Arrangement according to item 1, characterized in that the one closure device is designed as a cold air flap and the other closure device as a removal flap. 3. Arrangement according to item 1, characterized in that the removal flap and i the gate valve are locked against each other. For this 1 sheet drawing