EP2324289A2

EP2324289A2 - Method and device for conveying combustion residues

Info

Publication number: EP2324289A2
Application number: EP09781866A
Authority: EP
Inventors: Alan Bullock
Original assignee: Clyde Bergemann DRYCON GmbH
Current assignee: Clyde Bergemann DRYCON GmbH
Priority date: 2008-08-28
Filing date: 2009-08-14
Publication date: 2011-05-25
Also published as: US20110203534A1; WO2010023119A3; CN102317688A; DE102008044709A1; WO2010023119A2

Abstract

The present invention relates to a method for conveying combustion residues (6) in a conveying direction (2) along a conveying path out of a combustion chamber (1), comprising the following steps: a) conveying the combustion residues (6) out of the combustion chamber (1) by means of a conveying device (2) which has at least one housing (4); b) generating a first pressure level (12) in the housing (4); c) after-treating the combustion residues (6) in a treatment device (5) arranged in the conveying path; d) generating a second pressure level (13) downstream of the treatment device (5) in the conveying direction (7) of the combustion residues (6) by introducing a fluid (14) so as to form a pressure gradient.

Description

Method and device for conveying combustion residues

The present invention relates to a method and a device for conveying combustion residues in a conveyor along a conveying path from a combustion chamber. The invention finds particular application in the combustion of fossil fuels and / or waste incineration plants.

When removing the slag, ash, soot and the like, hereinafter referred to as "combustion residues", it is of particular importance to achieve on the one hand targeted solidification or solidification of the hot, partially still melted materials, so that in particular a promotion or further processing of this In addition, it is also desirable to use the energy still present in the hot material and thus to improve the overall efficiency of the plant or of the combustion boiler.

After initially assuming that a quenching in the water bath is required for the promotion of hot materials (so-called wet discharge), so-called dry exhaust systems have prevailed since the 90s. In this case, the hot material is placed on conveyor belts and transported there further, wherein optionally an afterburning or targeted cooling of the hot material is also partly carried out on the conveyor belt. It immediately becomes apparent that the materials used in this case, in particular the conveyor belt, must withstand the high temperatures, the corrosive environment and / or the high mechanical load. These conveyor belts are regularly encapsulated in relation to the external environment, that is to say they have a housing which prevents combustion gases, which are still generated during the treatment of the material, from readily escaping into the environment. In addition, the combustion boilers operated mainly with a slight negative pressure, so that the combustion gases produced by the material are drawn off by a corresponding suction to the combustion boiler.

Reference may be made to EP 0 471 055 Bl for an energetically useful extraction device which is specially equipped with regard to the cooling behavior. There it is shown that it makes sense to cool the hot material in two separate cooling stages with an intermediately stored comminution step for the hot material. In particular, a cooling air flow is to be realized according to the counter-current principle, which is provided at the end of the second cooling stage and at the end of the first cooling stage. There special effects with regard to the comminution of the hot material and the redistribution are explained, so that overall a more effective operation of the combustion boiler should be possible.

Accordingly, it is therefore known to carry away the combustion residues by means of conveyors and thereby (at the same time) also to undergo an aftertreatment. Different aftertreatments may be required, such as e.g. a portioning, a separation, a comminution of combustion residues. In these post-treatments, devices may be used in which the delivery cross-section for the combustion residues is reduced, so that there are delivery bottlenecks. The known systems tend occasionally disturbances in the range of these funding constraints, especially due to unwanted accumulation of material in the field of these facilities.

The object of the present invention is therefore to at least partially solve the problems resulting from the prior art and, in particular, to provide a method and a device with which an improved removal of combustion residues is achieved. In particular, the method should enable trouble-free operation of the conveying device and / or the treatment device (eg a crusher). With the device should also be simple design and a cost-effective retrofitting of known systems can be achieved.

These objects are achieved by a method according to the features of patent claim 1 and a device according to the features of patent claim 10. Further advantageous embodiments of the invention are specified in the dependent formulated claims. It should be pointed out that the features listed individually in the dependent formulated claims can be combined with one another in any technologically meaningful manner, and define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

To solve the problem, the inventive method for conveying combustion residues in a conveying direction along a conveying path from a combustion chamber comprises the following steps: a) conveying the combustion residues from a combustion chamber by means of a conveyor having at least one housing; b) generating a first pressure level in the housing; c) aftertreatment of the combustion residues in a treatment device arranged in the conveying path; d) generating a second pressure level in the conveying direction of the combustion residues behind the treatment device by introducing a fluid to form a pressure gradient.

Step a) relates in particular to the task of combustion residues on a conveyor belt, which is arranged in the housing of the conveyor. The housing encapsulates the conveyor belt and the combustion residues transported in it against the environment. In this (first) housing, a first pressure level is now set during the operation of the device (step b)). For this purpose, in principle, the combustion boiler operated with negative pressure will provide, if necessary, this negative pressure can be adjusted by additional suction units, air additions and / or blowers.

During step c), a subsequent treatment of the combustion residues takes place in a treatment device arranged in the conveying path. In particular, the conveying path leads through the treatment device, which forms a supply bottleneck. The treatment device may in this case be e.g. a crusher, hammers, grinders, flaps, sieves or the like.

With step d) should now be achieved that either certain portions of the combustion residues do not penetrate into the treatment facility and / or the funded by the treatment facility combustion residues are safely removed and not reenter the treatment facility and thus the funding bottleneck.

By forming a second pressure level, which is lower than the first pressure level for setting a pressure gradient, it is ensured that the combustion residues can not (again) enter the treatment device counter to the intended conveying direction. The pressure gradient is directed from a location of higher pressure to a location of lower pressure and at the same time substantially corresponds to the conveying direction. Thus, for example, the first pressure level may correspond to the negative pressure of a combustion chamber which is connected to the housing of the conveyor. In practice, a supply of air into the housing is allowed to supply the combustion chamber with air, so that it can flow into the combustion chamber after flowing through the housing. In the known methods and devices, the negative pressure of the first pressure level frequently produces a state in which combustion residues already conveyed through the treatment device are conveyed in the opposite direction to the conveying direction.

- A - which are sucked back into the treatment facility. This is the case in particular with very fine ash residue. If the treatment device is designed, for example, as a comminution device for relatively large combustion residues, there is a risk that this comminution device will have malfunctions due to deposits of combustion residues after a relatively short time.

This problem is solved by the present invention by introducing a fluid, which may preferably comprise at least air, water or water vapor, wherein by means of a Venturi effect, a negative pressure is generated, which forms a second pressure level behind the treatment device. If one now ensures that the second pressure level is lower than the first pressure level, a pressure gradient results, which points from the input side of the treatment device to the outlet side of the treatment device and thus in the conveying direction, whereby it can always be ensured under all operating conditions that no combustion residues, such as ash or vapors, are sucked back into the treatment facility. In this case, the first pressure level preferably corresponds to the negative pressure of the combustion chamber and the second pressure level corresponds to a lower pressure to generate a suction effect in the direction of the conveying direction of the combustion residues.

For the sake of completeness, it should be pointed out that the conveying direction is defined by the travel of the combustion residues in the conveying device.

In a preferred embodiment of the invention, it is provided that the second pressure level between 20 to 600 mbar, preferably between 80 to 150 mbar lower than the first pressure level is set. These pressure levels have proven to be sufficient and can also be produced in a technically simple manner, for example. With nozzle means.

In another advantageous embodiment of the invention it is provided that the fluid at a speed of at least 4 m / sec, preferably from at least 10 m / sec, is initiated. In this case, increasing the speed due to the Venturi effect to achieve a gain of a negative pressure generated. Higher speeds can be generated in particular with nozzle means, with the aid of an exit velocity of the fluid can be controlled from the nozzle means. In particular, such a very precise control of the speed and the discharge direction of the fluid with the corresponding nozzle means in a simple manner possible.

In this context, it is also advantageously provided that the fluid is supplied at a pressure of 4 to 10 bar. The supply of the fluid can be done either in direct form or with the interposition of a nozzle means. One of the advantages of this pressure range is that a pressure of 4 to 10 bar can be provided inexpensively by simple means and at the same time offers a sufficient pressure level for a downstream acceleration of the fluid with nozzle means. Depending on the application, these pressures are based on the ambient air pressure or the pressure on the outlet side of the nozzle means.

Furthermore, according to another advantageous embodiment of the invention, it is provided that at least the first pressure level, the second pressure level, a temperature or a fluid content in the housing is detected. This can be done, for example, with measuring means, which are arranged at least in front of, in or behind the treatment device. Thus, for example, with pressure sensors arranged in front of and behind the treatment device, the correct setting of the desired pressure gradient can be monitored. In another embodiment, it is possible to control the air temperature or the temperature of the combustion residues to control in a predetermined manner and depending on the fluid supply and activity of the treatment device. Furthermore, it is possible to detect a fluid content in the housing. This means in particular that a moisture in the housing section between the treatment device and the point with the introduction of the fluid is monitored. This can be done, for example, directly behind the treatment device by arranging a measuring device for detecting Solution of the fluid content done, so that in case of an unwanted promotion of the fluid flow against the conveying direction in the direction of the treatment device, this operating condition is detected immediately and countermeasures can be taken. Such countermeasures can include, for example, a control of the fluid supply, the air supply and / or a return of gaseous and fumigant combustion residues. Thus, for example, by increasing the fluid supply, the negative pressure of the second pressure level can be increased and a return of the combustion residues counteracted. Alternatively, by increasing the air supply in the first housing section, the first pressure level can be raised, so that the negative pressure formed there is reduced, which also counteracts a return of the combustion residues counter to the conveying direction. Furthermore, finally, the fluid supply can be completely interrupted if, despite all measures, the risk of a return of the fluid and the combustion residues. In addition, it is possible to increase the pressure gradient between the first pressure level and the second pressure level by a return in the conveying direction downstream of the treatment direction return of gaseous and smoky combustion residues.

It is advantageous to at least partially recycle gaseous and smoky combustion residues into the combustion chamber. In this case, for example, on the housing in the conveying direction behind the means for introducing a fluid conduit means for an at least partial recycling of gaseous and smoky combustion residues are provided in the combustion chamber.

In a likewise advantageous embodiment of the present invention, it is provided to monitor at least one region immediately before or after the treatment device (ie in particular in front of the nozzle means) for the presence of the fluid and in the presence of the fluid as a function of at least one detected measured value, at least the Pressure gradients to increase the return or the air supply or reduce or interrupt the supply of fluid. In order to prevent an unintentional and uncontrolled leakage of, for example, gas and smoke combustion residues at the end of the conveyor from the housing, it is advantageously provided that in the conveying direction downstream of the treatment direction at least in the housing or at a housing outlet, a fluid barrier is generated. This can be achieved, for example, by providing nozzle means for generating a fluid barrier in the conveying direction downstream at least in the housing or at a housing outlet. Such a fluid barrier can, for example, consist of a (hot) air flow or a liquid flow which is similar to a sprayed liquid curtain. As a result, the escape of gases, smoke and other particles is efficiently reduced, which, for example, the safety of operating personnel is beneficial.

Finally, in another advantageous embodiment of the method according to the invention, provision is made for an inlet direction of the fluid entering the housing to be selected such that it has at least one directional component in the conveying direction of the combustion residues. For this purpose, the inlet direction of the fluid can be divided into different (preferably orthogonal) directional components, which, when combined, result in the direction of entry. If at least one directional component lies in the direction of the conveying direction, this supports the transport of the combustion residues. In particular, this is the case when the inlet direction of the fluid has an angle between 10 ° and 80 ° with respect to the conveying direction. In particular, such angles, which correspond, for example, 30 ° - 60 °, are advantageous because they simultaneously generate a fluid flow, which causes the desired negative pressure and the fluid flow due to its kinetic energy, the promotion of combustion residues additionally supported.

The device proposed by the invention for conveying combustion residues along a conveying path with a conveying device has at least one housing and a treatment arranged in the conveying path. treatment device for the treatment of combustion residues. In this case, as seen in a conveying direction of the combustion residues behind the treatment device at least one nozzle means for introducing a fluid into the housing and the fluid is accelerated when flowing through the nozzle means for generating a second pressure level in the conveying direction behind the treatment device, solves the task of the invention also. By the nozzle means according to the invention for introducing a fluid into the housing, a second pressure level in the conveying direction is set, in particular in the manner described above, which is effectively lower than the first pressure level and thus forms a pressure gradient. The negative pressure generated by the introduced fluid thus ensures a constant delivery of combustion residues in the conveying direction, whereby the reliability of the device is significantly improved.

As a nozzle means here in particular a system with several in the housing with a distance to the treatment unit is used. The nozzles may be designed with a common fluid supply, so that e.g. a pump needs-oriented (in terms of time and amount) introduces the fluid through the nozzle into the housing. The distance to the treatment unit is in particular in a range of less than 5 m, preferably even less than 2 m or even in the range of 20 cm to 1 m. It is further preferred that an arrangement of the nozzle distributed over the circumference of the housing is made, in which case a uniform distribution is not mandatory here. The arrangement of the nozzles is preferably carried out in a horizontal plane. The nozzle means are adapted to accelerate the fluid (especially water) so that the fluid enters the housing at a sufficiently high velocity to generate suction therefrom away from the treatment device.

In another preferred embodiment of the device according to the invention it is provided that the housing in the conveying direction behind (downstream) the nozzle means conduit means for an at least partial recycling of gaseous and smoky combustion residues in the combustion chamber are provided. As a result, (unwanted) shares of combustion residues such. B. fly ash, are recycled to a post-combustion in the combustion chamber.

Furthermore, it is provided in the device according to the invention according to another preferred embodiment that at least one measuring means is arranged at least in the conveying direction in front of or behind the treatment device, that is connected to a control device for controlling the fluid supply, the air supply and / or recirculation with control or regulating means , In particular, the arrangement of at least one measuring means for measuring moisture in front of the nozzle means or in front of or in the treatment device enables reliable monitoring as to whether combustion residues and / or fluid are fed back against the conveying direction. If such a state is detected, the appropriately programmed control device, which is, for example, a programmable electronic control device, can execute corresponding control or regulating measures.

It is also particularly advantageous if the control device is designed to determine a pressure gradient. In this case, a controlled adjustment or regulation can also take place as a function of the at least one pressure gradient. For example, if the pressure gradient drops below a predetermined threshold, the controller may take appropriate countermeasures to increase the pressure gradient to the desired level, or institute protective measures for the safety of the device and the operator.

Finally, according to another advantageous development of the invention, it is provided that an air inlet is provided on the housing in the conveying direction before the treatment device. With this preferably controllable air inlet, the air supply to the combustion chamber and thus the first pressure level in the housing can be influenced. The invention finds particular application in combination with one of the following boiler plants: Boiler plant for the improvement of fossil fuels (coal, lignite, ...), waste incineration plants, etc., these preferably being operated with the methods described herein according to the invention and / or equipped with the device according to the invention is. If necessary, this concept can also be applied to other conveyor systems that are subject to a production bottleneck (eg, a mill or a crusher type).

The invention and the technical environment are explained in more detail below with reference to the attached figure. It should be noted that the figure shows a particularly preferred embodiment of the invention, but is not limited thereto. 1 shows schematically a device according to the invention for conveying combustion residues, which is also suitable for carrying out the method according to the invention.

In Fig. 1, a combustion chamber 1 is shown, are burned in the fossil fuels or waste. Below the combustion chamber 1, a conveyor 2 is arranged, which consists of conveyor belts 3, housing 4 and a treatment device 5 arranged in the conveying path. With the conveyor belt 3, the combustion residues 6 are transported along the conveying direction 7, wherein they emerge after passing through the treatment device 5, which is designed as a shredding device 8, at a housing outlet 9. The part of the housing 4 between the combustion chamber 1 and the treatment device 5 can also be referred to as the first housing section and the part of the housing 4 after the treatment device as the second housing section, whereby these can also be designed separately.

Above the treatment device 5, an air inlet 10 is provided, can flow through the air in the direction of the arrow 11 in the housing 4, from where it passes into the combustion chamber 1, which is operated with a slight negative pressure. In this area of the housing 4 there is a first pressure level 12. In the area behind (downstream) of the treatment facility 5, there is a against a second pressure level 13, which is characterized by a lower pressure than the first pressure level 12. The second pressure level 13 is generated by introducing fluid 14 (water) through nozzle means 15 in a region below the treatment device 5. The nozzle means 15 are inclined at an angle α relative to the conveying direction 7 provided at this position. Due to the inclination, the fluid 14 issuing from the nozzle means 15 simultaneously generates a negative pressure and conveys the combustion residues 6 in the direction of the housing outlet 9 due to the flow direction of the fluid. At the housing outlet 9, further nozzle means 15 are provided from which a fluid 14 emerges. to create a fluid barrier 16. As a result, z. B. prevents the unwanted leakage of smoke and gas from the housing 4. Such undesirable constituents of the combustion residues can be recycled via a return, which opens into the combustion chamber 1 via a conduit 18 by means of a valve 17. To control or regulate the device, a control device 19 is provided, which is connected via control lines 20 simultaneously with the air inlet 10, the valve 17, the nozzle means 15 and measuring means 21. The measuring means 21 may be formed, for example, for detecting pressure and moisture. If water is used as the fluid 14, it can be detected immediately with the aid of the measuring means 21 if this fluid were transported counter to the conveying direction in the direction of the treatment device 5 or even through it. In addition, monitoring of a pressure gradient between a front side 22 and a rear side 23 of the treatment device 5 can be monitored very accurately in a design of the measuring device 21 for pressure detection. If the pressure gradient between the front side 22 and the rear side 23 decreases undesirably, the pressure level 12 can be raised by additional air 11 or the second pressure level 13 can be lowered by introducing additional fluid 14, optionally with individual or combined measures. In addition, it is possible to lower the second pressure level 13 in addition by the return of combustion residues through the conduit means 18. With the device thus executed, it is possible to ensure a permanent and trouble-free operation of the treatment device 5.

The present invention is not limited to the embodiment described and illustrated above. Rather, numerous modifications of the invention within the scope of the claims are possible without departing from the spirit and scope.

LIST OF REFERENCE NUMBERS

1 combustion chamber

2 conveyor

3 conveyor belt

4 housing

5 treatment device

6 combustion residues

7 conveying direction

8 crusher

9 housing exit

10 air intake

11 air

12 first pressure level

13 second pressure level

14 fluid

15 nozzle means

16 fluid barrier

17 valve

18 conduit means

19 control device

20 control line

21 measuring equipment

22 front side

23 back side

Claims

claims

1. A method for conveying combustion residues (6) in a conveying direction (2) along a conveying path from a combustion chamber (1), comprising: a) conveying the combustion residues (6) from the combustion chamber

(1) by means of a conveyor (2) having at least one housing (4); b) generating a first pressure level (12) in the housing (4); c) aftertreatment of the combustion residues (6) in a treatment device (5) arranged in the conveying path; d) generating a second pressure level (13) in the conveying direction (7) of the combustion residues (6) behind the treatment device (5) by introducing a fluid (14) to form a pressure gradient.

2. Method according to the preceding claim, characterized in that the second pressure level (13) between 20 to 600 mbar lower than the first pressure level (12) is set.

3. The method according to any one of the preceding claims, characterized in that the fluid (14) at a speed of at least 4 m / sec. is initiated.

4. The method according to any one of the preceding claims, characterized in that the fluid (14) is supplied at a pressure of 4 to 10 bar.

5. The method according to any one of the preceding claims, characterized in that at least the first pressure level, the second pressure level, a temperature or a fluid content in the housing (4) is detected.

6. The method according to any one of the preceding claims, wherein gas and smoke-like combustion residues (6) are at least partially recycled into the combustion chamber (1).

7. The method according to any one of the preceding claims, wherein at least one area immediately before or after the treatment device (or before the nozzle means) is monitored for the presence of the fluid and in the presence of the fluid in dependence on at least one detected measured value, at least the pressure gradient, the return or the air supply is increased or the supply of the fluid is reduced.

8. The method according to any one of the preceding claims, characterized in that in the conveying direction (7) downstream of the treatment direction

(5) at least in the housing (4) or at a housing outlet (9) a FIU idsperre (16) is generated.

9. The method according to any one of the preceding claims, characterized in that an inlet direction of the entering into the housing (4) fluid is selected so that it has at least one directional component in the conveying direction (7) of the combustion residues (6).

10. A device for conveying combustion residues (6) along a conveying path with a conveyor (2), the at least one housing

(4), and a treatment device (5) arranged in the conveying path for treating the combustion residues (6), wherein in one

Delivery direction (7) of the combustion residues (6), as seen behind the treatment device (5), at least one nozzle means (15) for introducing a fluid (14) into the housing (4) is provided and the fluid (14) when flowing through the nozzle means (15) for generating a second pressure level (13) in the conveying direction (7) behind the treatment device

(5) is accelerated.

11. Device according to the preceding claim, characterized in that on the housing (4) in the conveying direction (7) downstream of the nozzle means (15) conduit means (18) for an at least partial recirculation of gaseous and smoky combustion residues (6) in the combustion chamber ( 1) are provided.

12. Device according to one of the preceding claims 10 or 11, characterized in that at least in the conveying direction (7) before or after the treatment device (5) at least one measuring means (21) is arranged, with a control device (19) for controlling the fluid supply , the air supply or the return is connected to control or regulating means (10, 15, 17).

13. Device according to the preceding claim, characterized in that the control device (19) is designed to determine a pressure gradient.

14. Device according to one of the preceding claims, characterized in that on the housing (4) in the conveying direction (7) in front of the treatment device (5) an air inlet (10) is provided.

15. A boiler with a device according to one of claims 10 to 14, adapted for a method according to claim 1 to claim 9.