DE102011119533A1 - Linear fuel conveyor diverter for flowable solid fuels, particularly pellets and wood chips, has linearly displaceable upper part consisting of central material suction line, alternative suction line, central return air duct - Google Patents

Abstract

The linear fuel conveyor diverter has a linearly displaceable upper part consisting of a central material suction line (1), alternative suction line (2), central return air duct (3), alternative return air duct (4) and a movable carrier unit (5). A firmly arranged lower part consisting of a fixed carrier unit (6), another material suction line (7) to the extraction point, another return air duct (8) and a sealing is provided. The flow direction of the material suction line and the return air duct are reversed by the linear displacement of the upper part from one position to another position.

Description

In general, a suction and a return air line is required for the pneumatic transport of free-flowing fuel, such as pellets, from the storage room to supply a boiler. When transporting fuel both lines lead from the fuel storage room to the reservoir of the boiler and back. The fuel is removed in the storage room at a sampling point, sucked to the boiler and the return air is guided back to the sampling point. The negative pressure is applied either by a suction or pressure fan.

It is thus a closed air cycle.

The cable routing is usually done by means of flexible plastic tubing, which can be laid easily and with little planning effort. For the fuel pellets usually hoses with 50 mm inner diameter are used. For other free-flowing fuels, such as coal dust or wood chips, larger hose diameters may be necessary.

For low-energy and passive houses is usually sufficient for a sampling point for the storage of the annual stock of fuel, for single-family homes usually not. There are thus several sampling points in the fuel storage room needed to ensure an automated and trouble-free operation over a complete heating season and at the same time to be able to empty the storage room evenly. Thus, a system for changing the sampling points is required.

In the DE 7556003 Such a conveyor is described. It is a suction blower with cyclone, separator and storage tank. In addition, a pipe switch is described, which is in communication with the suction pipes. The suction pipes are provided with over pipes, which serve for air return. The switchover takes place by means of a level switch to a next extraction point. The return air can only be passed through the annular gap in this system. A change from return air line and suction line to the diverter valve is not provided, so even within a sampling point to the transfer tube automatic fault repair, if, for example, the suction line is clogged, not possible.

For the automated change of the suction and return air branch lines to several sampling points there are various possibilities.

• (1) Die erste Methode wurde oben bereits in der DE 1556003 beschrieben.
• (2) Die zweite besteht im Einsatz von linearen Umschalteinheiten. Dabei wird die fest auf einem Linearschlitten befindliche Saug- und Rücklaufleitung automatisch auf die nächste Entnahmestelle weitergeschoben und der Wechsel der Entnahmestelle findet statt. Nachteilig bei diesem System wirkt sich die Tatsache aus, dass bei einem Störfall wie einer verstopften Saugleitung bei oder in der Nähe der Entnahmestelle dieser nicht behoben werden kann. Üblicherweise wird das dadurch gelöst, dass die Saugleitung einer Entnahmestelle durch Fliessrichtungsumkehr von Saug- und Rückluftleitung mit Rückluft auf der Saugseite freigeblasen wird. (Die Saugleitung wird zur Rückluftleitung und die Rückluftleitung wird zur Saugleitung.)
• (3) Die dritte Methode arbeitet mittels Absperrschieber. Über eine Verteilweiche sind 2 oder mehrere Stichleitungen mit der zentralen Saug- und Rückluftleitung verbunden. Die nicht gewünschten Entnahmestellen werden mittels eines automatischen Absperrschiebers verschlossen und die gewünschte Stichleitung gleichzeitig bei Saug- und Rückluftseite freigegeben. Nachteilig bei diesem System ist, wie in Methode 1 und 2 beschrieben, dass eine verstopfte Saugleitung im Störfalle nicht automatisch mit Rückluft freigeblasen werden kann.
• (4) Die vierte Methode besteht in der Umschaltung und ist im EP1 052 456 B1 beschrieben. Diese Methode basiert inhaltlich auf dem DE 1556003 in Form einer Umschaltung auf dem Prinzip eines Drehschiebers. Bei diesem System kann sowohl auf eine weitere Entnahmestelle umgeschalten als auch Saugleitung und Rückluftleitung gewechselt werden. Mit diesem System entfallen die in Methode 1 und 2 beschriebenen Nachteile. Eine verstopfte Saugleitung bei der Ansaugstelle kann damit in der Regel durch den Wechsel von Saug- und Rücklaufleitung mittels Rückluft freigeblasen werden. Der Drehschieber hat jedoch den Nachteil, dass bei einem Wechsel von Saugluftleitung und Rückluftleitung innerhalb einer Entnahmestelle (Saugleitung wird zur Rückluftleitung und Rückluftleitung wird zur Saugleitung) die beiden Leitungen um 180° verdreht werden müssen. Da die Leitungen in Form von Kunststoffschläuchen einen Durchmesser von mindestens 50 mm aufweisen, ist dieses Verdrehen nur mit ausreichend langen Schlauchen möglich, damit diese nicht deformiert werden.

Before the confluence of the return line in the storage room and after the exit of the suction line from the storage room, the division takes place in several branches to the sampling points. The division is made according to the prior art as follows:

• (1) The first method was already mentioned above in the DE 1556003 described.
• (2) The second is the use of linear switching units. The suction and return line, which is fixed on a linear slide, is automatically moved to the next extraction point and the change of the extraction point takes place. A disadvantage of this system is the fact that in an accident such as a clogged suction line at or near the sampling point this can not be resolved. This is usually achieved by blowing the suction line out of a withdrawal point by reversing the flow direction of the suction and return air line with return air on the suction side. (The suction line becomes the return air line and the return air line becomes the suction line.)
• (3) The third method works by means of gate valve. 2 or more spur lines are connected to the central suction and return air line via a diverter switch. The non-desired sampling points are closed by means of an automatic gate valve and the desired spur line released simultaneously at the suction and return air side. A disadvantage of this system, as described in Method 1 and 2, that a clogged suction line in case of malfunction can not be automatically blown free with return air.
• (4) The fourth method consists in switching and is in EP1 052 456 B1 described. This method is based on the content DE 1556003 in the form of a changeover on the principle of a rotary valve. In this system, it is possible to switch over to another extraction point as well as to replace the suction line and return air line. This system eliminates the disadvantages described in Methods 1 and 2. A clogged suction line at the suction point can thus be blown out by the change of suction and return line by means of return air usually. However, the rotary valve has the disadvantage that when a change of suction air line and return air line within a sampling point (suction line is to the return air line and return air line to the suction line), the two lines must be rotated by 180 °. Since the lines in the form of plastic hoses have a diameter of at least 50 mm, this twisting is only possible with sufficiently long hoses, so that they are not deformed.

This usually requires a distance of at least 1.5 to 2 meters to ensure trouble-free operation. However, this place is not always sufficiently available.

Another disadvantage of this solution is that in the installation room of these switching devices are always moving hose parts, which can also lead to injury to the operator in the worst case.

On the other hand, not professionally laid hoses in the rotation range of the plate can lead to leaks in the conveyor system, which can adversely affect the necessary negative pressure in the system and can lead to a standstill.

In addition, the diametrically arranged on the rotary valve suction and return air lines are not clearly protected during assembly on site for confusion, since the positions of the hose pairs (for suction / return air) must match for each removal point between the rigid base and the movable upper part.

All the methods described above essentially have a common feature. The changeover mechanism is usually made of metal (including the necessary pieces of pipe), the spur lines to the storage room or to the reservoir of the boiler made of plastic hoses.

Changed conditions to already existing systems

Biomass boilers expect the same standard of comfort and reliability as fossil fuels. At the same time, the heating and storage rooms in which biomass heating systems are installed are often very small.

Thus, the laying of suction and return air lines can often be laborious and expensive to rework, especially if the required space for changing facilities of suction and flow lines is not available.

One of the most important problem is that after refilling a storage room, for example, with pellets multiple suction can be clogged at the same time. This can have a very unpleasant impact on a full storage room. Remedy provides only a change of suction and return air line.

Another important point is the ease of installation of the system. Since usually at least 50 mm thick plastic hoses are used is a reversal of the flow direction by rotary valve 180 ° critical, a linear displacement of the upper part, for example, 200 mm to the next branch, however, completely unproblematic.

The same applies to the simple laying of plastic hoses, since the suction and return air line are directly next to each other. With a rotary vane solution this is not the case due to the 180 ° offset.

Another alternative requirement in a new system may be that a malfunction in a suction line is detected immediately and the changing device between the sampling points immediately reacts thereto. Usually, the detection of the prior art is done indirectly. The filling level switch of the storage tank on the boiler recognizes after several unsuccessful attempts of the suction system that no fuel was conveyed and only then switches over to a new extraction point. The conveyor failure may have been caused either by blockage of a sampling point or by complete emptying of this. This delayed reaction can often last for several minutes. During this time, the boiler is usually switched off, which can lead to a considerable failure of heating line during this time. Especially in many houses from old stock, this disadvantage can have a very adverse effect due to large heat losses.

Object of the present invention and description of the individual components

The purpose of the linear fuel transfer switch is to meet the requirements described above.

This includes the change of the flow direction of suction and return air line within a sampling point. This can be corrected automatically blockages in the suction line of a sampling point. By linear displacement, the problem of twisting of at least 50 mm thick plastic hoses is solved at the same time. At the same time a line damage is avoided by the rotational movement and achieved reduction in space requirements.

The change of suction and return air line to other sampling points is of course also guaranteed.

For installations in new buildings, a withdrawal point is usually sufficient on account of the small annual amount that is required; for all other objects, two or more removal points are necessary. This requires a switch in front of the storage room. This switch or switch has to fulfill several tasks. While the pure "switching solutions" in Incidents can lead to failures, solutions with rotary valve are relatively expensive to assemble. In addition to a length of about 1.5-2 meters a Ausdrehstrecke is needed. This is necessary if the suction line and the return line are turned by turning the slide by 180 °. This occurs especially when it comes to a larger number of sampling points. Thus, the rotary valve is correspondingly large, sufficient space in the depth must be available in order to use this system can. In addition, it can happen that there are leaks at the joints, if the Ausdrehstrecke is too short.

Object of this invention is to avoid these disadvantages by a linear movement takes place when changing the sampling points, which can swap in case of failure and suction and return air line.

Suction systems for the extraction of fuels usually work with a negative pressure of approx. 5000-10000 Pascal. The air circuit of the system is tight and closed. Experience has shown that a blockage of a sampling point leads to an immediate increase in the negative pressure in the reservoir of the suction system. Conversely, the negative pressure drops very much in the system when a sampling point is completely empty. This increase in pressure or waste can be detected very easily technically with a differential pressure sensor. This gives the possibility of an immediate reaction to irregularities. The fuel feed switch changes instantly either the sampling point or reversed suction line and return line. This avoids long downtimes and unnecessarily high power consumption due to long runtimes of the suction turbine.

Finally, the complete mechanics and all flexible hose parts should be housed in a closed housing.

The linear fuel conveyor is in the 1 - shown:

1 Tilt view of the switch in "normal" working mode at removal point E1

2 Angled view of the switch in the blow-out mode

3 Angled view of the withdrawal point E2

4 Outline, cross-section and plan view of a possible variant

5 Cut BB off 4 (possible variant of the linear drive)

6 Cut AA off 4

7 Outline and cross-section of a fuel transfer gate integrated in the housing

8th possible alternative variant to the illustrations in 1 - 7

The principle of the fuel transfer gate:

In 1 is the normal operation shown. The rigidly installed material suction line ( 7 ) takes fuel at point S5 of the extraction point E1. This flows via S4, the material suction line ( 1 ) as well as points S2 and S1 to the reservoir of the boiler. Via the central return air line ( 3 ) and the points R1 and R2 and then via the return air duct ( 8th ) and the points R4 and R5, the return air is fed back to the withdrawal point R5. This is normal suction operation without interference.

In order to freeze a clogged pipe at the removal point E1, it is necessary, the flow direction of the material suction ( 7 ) as well as the return air line ( 8th ) to reverse. This is shown by 2 , This is done by the movable carrier unit ( 5 ) is moved to the left by means of a linear drive.

Thus, the alternative suction ( 2 ) is moved with the point S3 to the point R4 and brought to cover with the tube in the rigid base. The also on the movable carrier unit ( 5 ) located alternative return air line with the point R3 is simultaneously moved to the point S4 and there brought to cover with the tube in the rigid base. This changes in the lines ( 7 ) and ( 8th ) the flow direction. Return air flows through line ( 7 ) and can blow out any obstructions, while the line ( 8th ) to the material suction umgewidmet takes over the task of material transport.

With this principle, the reversal of the flow direction with a linearly movable unit is possible for the first time.

If the movable carrier unit is moved to the removal point E2 to the right, the procedure is the same as at removal point E1. (please refer 3 ) Any number of extraction points work according to the same principle.

4 shows a possible structural embodiment. The displacement of the linear upper part OT, for example, by a gear with motor, which is mounted on the upper part (OT), and a rack in the lower part UT done.

The necessary change of any extraction point takes place according to the prior art by a signal of the level indicator from the reservoir of the boiler. If after several unsuccessful suction attempts no "full message" of the reservoir is detected, the change takes place.

A special embodiment provides relief against too long reaction times.

Since the state-of-the-art vacuum for reliably transporting pellets must be approximately 5,000 to 10,000 pascals, this can be achieved with a simple differential pressure sensor (US Pat. 13 ) are reliably monitored. This sensor is expediently connected by means of a connection ( 12 ) to return line ( 3 ) and has a sufficiently large switching hysteresis.

This makes it possible to react directly to irregularities in the suction system for the first time and does not require any unnecessary attempts to set the material flow in motion. This saves time but also energy, because the suction turbine, for example, in a 50 mm suction and return air line with about 1500 watts connected load, quite a lot of energy. If the pressure in the suction system rises significantly above 10,000 in the direction of 25,000 pascals, a blockage at the intake point can be assumed. The reaction to this situation is quite simple with the flow direction reversal. (In 2 described)

If the pressure in the suction system now drops, it can be assumed that there is no more fuel at any extraction point and the pressure drops well below 5000 Pascals in the system. This detection is also very easy to get under control with the change of the sampling point. (in. 3 described)

The linear displacement unit makes it possible for the first time to be able to build very compactly, even with a larger number of extraction points (eg, 5-10), which can often be of great advantage in small heating rooms. The advantage arises from the fact that with the linear principle every additional removal point is simply ranked next to the basic unit. This creates a slim space-saving design on the wall.

How to save on assembly time and Steltfläche is in 7 shown. The fuel feed switch forms a prefabricated unit consisting of housing back ( 16 ), the housing cover ( 18 ), the fire insulation ( 17 ) and the two fire protection sleeves ( 23 ) as well as the complete in 1 - 4 illustrated conveyor switch. This unit is mounted immediately in front of the fuel storage room, where the branch lines then open. From the rigid lower part of the feed switch each lead a usually made of plastic suction line ( 22 ) and a return line ( 21 ) to a sampling point. Any number of sampling points can be realized. At the same time, on the linearly displaceable upper part OT, a suction line, which is generally made of plastic, is (in each case 20 ) and return air line ( 19 ) connected to the reservoir of the boiler. The big advantage of this solution is that, unlike conventional solutions, there are no moving lines outside the housing. In addition to a quick installation and the low depth is emphasized. In some areas of Europe, including Germany, it is already permitted in terms of fire protection that fuel storage tanks and boilers may be located in a common room. Of course, this also includes the fuel transfer gate. In this case, the fire insulation ( 17 ) accounted for.

Even with the case solution, a differential pressure sensor ( 13 ) are installed in the line.

In 8th is an alternative variant to the previously explained principle. The effect is identical, but the alternative material suction line ( 31 ) as well as the alternative return air line ( 29 ) are not arranged in the movable upper part but in the rigid lower part. This solution is structurally complex to implement, since the alternative lines for the material or the return air for each sampling point must be designed specifically. However, there may be applications where the movable top has to be made more space efficient. In this case, this variant can be used.

Advantages of the invention:

• • In the event of a malfunction, the flow direction of the suction and return air lines can be reversed completely automatically; the clogged point in the suction line is blown open with return air and the malfunction is remedied
• • no rotation movement of the material suction or return air hoses when changing the extraction points or reversing the flow direction
• • easy laying of the suction and return air lines
• • low installation depth of the unit
• • If a differential pressure sensor is used, it is possible to react immediately to incidents
• • less assembly errors
• • No risk of injury, as moving parts are covered

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 7556003 [0005]
• DE 1556003 [0007, 0007]
• EP 1052456 B1 [0007]

Claims (8)

Linear fuel transfer gate for free-flowing solid fuels, in particular pellets and chips, with a linearly displaceable upper part (OT) consisting of central material suction line ( 1 ), Alternative suction line ( 2 ), central return air line ( 3 ), alternative return air line ( 4 ) and the movable carrier unit ( 5 ) and a rigidly arranged lower part (UT) consisting of a rigid carrier unit ( 6 ), Material suction line to the sampling point ( 7 ) and return air line to the sampling point ( 8th ) and a seal ( 11 ) characterized in that by the linear displacement of the upper part of the positions S2 / S4 and R2 / R4 to the positions R3 / S4 and S3 / R4, the flow direction of the material suction 7 and the return air line 8th is reversed. Linear fuel delivery switch according to claim 1, characterized in that the change in the flow direction of the suction line and return line is possible regardless of the number of fuel outlets on any sampling point. Linear fuel feed switch according to claim 1, characterized in that by the linear displacement of the upper part (TDC) from the positions S2 / S4 and R2 / R4 to the positions S2 / S6 and R2 / R6 from the fuel extraction point E1 to E2 or any number of others can be changed. Linear fuel-feed switch according to claim 1 to 3, characterized in that the linear displacement of the upper part (OT) by a arranged in the return line differential pressure sensor ( 13 ) is triggered Linear fuel-conveying switch according to claim 1 to 3, characterized in that the entire switch in a wall housing ( 16 ) is integrated. Linear fuel-conveying switch according to claim 1 to 3, characterized in that the entire switch in a wall housing (( 16 ) and a front cover ( 18 ) and a fire retardant insulation ( 17 ) is integrated. Linear fuel-feed switch according to claim 5 and 6, characterized in that the linear displacement of the upper part (OT) by a arranged in the return line differential pressure sensor 13 is triggered. Linear fuel conveyor switch characterized in that the principle after 8th is applied (reverse principle).

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