DE102010051489A1 - Solid fuel burner for rotary kiln, has swirl vane facing end of burner tube that has pre-combustion and main combustion portions with holes for controlled oxygen supply, nitrogen oxide reduction and for preventing caking of residues - Google Patents

Abstract

The burner has a hollow cylindrical combustion chamber that has exit radial to longitudinal axis to discharge ash. A swirl vane (8) is arranged in a position facing an end of diameter-reduced burner tube (9), in combustion chamber. The burner tube is comprised of pre-combustion portion (A) and main combustion portion (B) which include several holes (18,19) for controlled oxygen supply and cooling, nitrogen oxide reduction and for preventing caking of combustion residues. The number of holes in pre-combustion portion is larger than that in main combustion portion.

Description

The invention relates to a solid fuel burner with a substantially hollow cylindrical combustion chamber, which has a cooling jacket, a front side arranged Brenngutzuführung, arranged at the combustion chamber outlet substantially radially to the combustion chamber longitudinal axis ash discharge, a concentric to the combustion chamber subsequent or partially reaching into this, based on the Combustion reduced diameter burner tube and means for mixing the combustible material in the combustion chamber according to the preamble of claim 1.

From the DE 10 2007 017 101 A1 a solid fuel burner for lumpy to flowable fuels is previously known, which emanates from a hollow cylindrical burner body which is divided several times. An inner, inserted tube part is designed to rotate. A fuel input has a screw conveyor. Other fuel inputs are at an angle other than the first fuel input with screw conveyor available. An inserted, inner tube part, which represents the main combustion chamber, has on its inner circumference in the area of the ember bed knobs, spikes or similarly intermeshing acting elements. Also, a spiral is provided for the purpose of the kiln slag promotion towards discharge.

In the construction described above, a considerable effort is required to form a rotary tube including spirals for slag discharge, which must be avoided.

In this regard, in the DE 10 2007 039 273 A1 proposed a solid fuel burner, which assumes a hollow cylindrical configuration, which is dispensed with turning of an inner tube. Rather, in this solution, only intended for mixing arrangement of spikes, which are located on an axis, rotating. In addition, a rotating spiral spring is present, which also bears laterally on the inner peripheral surface of the pipe or parts. Even such a rotating spiral spring leads to increased costs in the production of a solid fuel burner.

From the foregoing, it is therefore an object of the invention to provide an advanced solid fuel burner with a substantially hollow cylindrical combustion chamber, which has a cooling jacket, which manages without means for conveying ash or slag from the combustion chamber and which by a targeted combustion air supply via a reduced output of nitrogen oxides, the design is overall inexpensive to manufacture and easy to maintain.

The object of the invention is achieved by a solid fuel burner according to the combination of features according to claim 1, wherein the dependent claims comprise at least expedient refinements and developments.

It is therefore assumed that a solid fuel burner with a substantially hollow cylindrical combustion chamber, which has a cooling jacket. The combustion chamber has a front end arranged Brenngutzuführung and a at the combustion chamber exit substantially radially to the combustion chamber longitudinal axis arranged ash discharge. Furthermore, a burner tube which adjoins the combustion chamber in a concentric manner or partially extends into it and which has a reduced diameter relative to the combustion chamber. Also, means for mixing the combustible material are realized in the combustion chamber.

According to the invention, in the combustion chamber facing the end of the burner tube, and as close as possible to the combustion chamber out, a swirl body, in particular designed as swirl vanes, available.

In the burner tube, there is a pre-combustion section and a main combustion section, and there are apertures or rows of holes in the burner tube whose number and / or passage areas increase from the pre-combustion section to the main combustion section for the purpose of controlled oxygen supply and simultaneous cooling, nitrogen oxide reduction, and prevention of combustion residue caking. The number and / or the passage area increases steadily or discontinuously in the burner tube. Where the swirling body receiving end of the burner tube is located above the ash collecting and -austragsraum, no openings or rows of holes are provided.

Ausgestaltend the burner tube is surrounded by a flame tube, wherein the oxygen supply via the spacer cavity between the burner and flame tube takes place. For blowing in atmospheric oxygen, a fan is coupled to the flame tube.

In the region of the swirl body, a tubular, substantially centric feed for recirculation air or for exhaust gas recirculation is formed.

At reaching the burner tube end of the combustion chamber, a storage area or a baffle plate for retaining the combustible material is provided.

By coupling a fuel supply screw at the feed side end of the combustion chamber, fuel is nachgefördert and simultaneously passed ash over the storage area or baffle plate in an adjoining in the conveying direction ash box, wherein in the ash box an ash discharge auger is provided.

In the longitudinal direction in the combustion chamber extends a rotating shaft with radially oriented arms for Brenngutdurchmischung. In or on the front side Brenngutaufgabebereich the combustion chamber is a Zündföhn to the combustion and gasification of the combustible material, eg. B. initiate in the form of pellets.

In the combustion chamber, a gasification of the combustible material is first introduced at temperatures of ≦ 800 ° C., wherein the residual oxygen content in the combustion chamber is set to about 6% by volume by means of air chambers arranged below the combustion chamber. For air supply, the combustion chamber to the air chambers directed openings or openings, whose dimensions are chosen so that the kiln is securely held back. The temperature in the pre-combustion section in the burner tube is set only slightly higher than the temperature in the combustion chamber, wherein in the main combustion section via another oxygen supply, the temperature is set to a value between about 1100 ° C to 1300 ° C at λ = about 1.4.

In one embodiment of the invention, it is possible to couple the auger for Brenngutzuführung drive side with the shaft for Brenngutdurchmischung to save additional drive means.

The cooling of the combustion chamber via a jacket by means of an outer tube and cooling fluid flowing therebetween.

The invention will be explained below with reference to an embodiment and with the aid of a figure.

The figure shows a longitudinal section through the burner assembly according to the invention.

The solid fuel burner according to the embodiment initially has a combustion chamber, formed by an inner tube 3 , on.

At a front end of the inner tube 3 is a fuel feed screw 1 arranged, which via an opening firing material in the inner tube, that promotes the combustion chamber. Also on this task-front page is a Zündföhn 12 ,

In the longitudinal axis direction of the inner tube 3 is an axis 2 with several arms 15 for mixing the combustible located.

The inner tube 3 the combustion chamber is from an outer tube 4 surrounded, being in the cavity between the inner tube 3 and outer tube 4 a cooling liquid is passed. An inspection opening 5 allows access to the combustion chamber.

Below the combustion chamber are air chambers 6 provided for supplying primary air, wherein the primary air through openings 14 is guided, located in the lower part of the inner tube 3 are located.

At the opposite end of the task area of the combustion chamber is a baffle plate 16 located, which restrains the firing and ensures a longer residence time this. About the selectable height of the baffle plate 16 can ash in the ash discharge box 17 get there and there by a screw conveyor 7 be transported away.

A burner tube 9 dives into the opposite end of the task front end of the inner tube 3 and has at his to the inner tube 3 pointing end a twisting wing 8th for fuel gas mixing. Inside the burner tube 9 There is a pre-combustion section A and a main combustion section B, in each of which openings or rows of holes 18 ; 19 are located.

The number and / or the passage areas of the rows of holes 18 ; 19 increases from section A to section B for the purpose of controlled oxygen supply and simultaneous cooling, the reduction of nitrogen oxides and to prevent the caking of combustion residues.

In the example shown, a radially circumferential row of holes is located in area A. 18 , In section B, however, six such rows of holes are formed.

The burner tube 9 is from a fire tube 11 Surrounded by spaced, over the distance cavity, the oxygen supply to the rows of holes 18 and 19 he follows. With the help of a blower 10 In this regard, secondary air can be supplied.

In the area of the swirl body 8th is a tubular feeder 13 available for recirculation air or exhaust gas recirculation.

The mode of operation of the solid fuel burner according to the invention is as follows.

In a first phase are about the screw conveyor 1 z. B. wood pellets in the combustion chamber, which is also to be regarded as a gasification chamber introduced. About the Zündföhn 12 a burning of the pellets is made. The wave 2 with arms 15 mixes the kiln. After the ignition of the fuel with the help of Zündföhns, the firing start phase begins. Here, an adjustment of the gasification temperature in the combustion chamber in the range of below 800 ° C., preferably about 700 ° C. About the control of the primary air by means of the openings 14 and the air chambers 6 the gasification begins, in that the residual oxygen content in the combustion chamber is subject to a reduction to approx. 6% by volume. The gasification process now takes place in the ember bed when the pellet feed is continued. The lambda value here lies in the range between 0.4 and 0.6. The air supply is further reduced for the continuing gasification process.

The subsequent phase is characterized in that the fuel gas over the swirl body 8th in the burner tube 9 entry. Here is over the first row of holes 18 in section A a first admixture of oxygen. The lambda ratio is approximately λ = 1. The oxygen supply through the rows of holes in sections A and B reduces harmful nitrogen oxides. The temperature in the section A extending to the combustion chamber is only insignificantly higher than the gasification temperature.

The final combustion phase takes place in the outlet area of the burner tube 9 instead, in section B with a larger number of rows of holes 19 , Here is another oxygen supply with temperature increase in the range of 1100 ° C to 1300 ° C. The lambda value here is approximately λ = 1.4 and the residual oxygen is between 4.5 and 6.5% by volume.

The air supply via the double wall arrangement 9 / 11 has the advantage of simultaneous cooling of the burner tube and prevents deposits of molten or melting fly ash. About the blower 10 In addition, steam can be supplied, which leads to a further reduction of nitrogen oxides.

For an improvement of the air supply in the so-called core stream, which is highly CO-containing, can still radial tubes in the field of the burner tube 9 be used. Essential for the function is the fact that the swirl body 8th in the pictorial representation as far as possible left, that is arranged to the gasification room. The swirl body not only increases the residence time of the gas, but also promotes its mixing.

LIST OF REFERENCE NUMBERS

1

Feed screw for fuel supply

2

Axis of the mixer

3

inner tube

4

outer tube

5

inspection opening

6

air chamber

7

Auger to the ash discharge

8th

swirl unit

9

burner tube

10

Blower for supplying secondary air

11

flame tube

12

Zündföhn

13

Exhaust gas recirculation

14

opening

15

poor

16

baffle plate

17

ash tray

18; 19

row of holes

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 102007017101 A1 [0002]
• DE 102007039273 A1 [0004]

Claims (10)

Solid fuel burner with a substantially hollow cylindrical combustion chamber, which has a cooling jacket, a frontally arranged Brenngutzuführung, arranged at the combustion chamber exit substantially radially to the combustion chamber longitudinal axis ash discharge, a concentric to the combustion chamber subsequent or partially into this reaching, based on the combustion chamber diameter-reduced burner tube and Means for mixing the combustible material in the combustion chamber, characterized in that arranged in the combustion chamber end of the burner tube, a swirl body, in particular designed as swirl vanes, wherein the burner tube has a precombustion A and a main combustion section B, in which openings or rows of holes are located their number and / or passage areas extend from the pre-combustion section A to the main combustion section B for the purpose of controlled oxygen supply and simultaneous cooling, nitrogen oxide red uzierung and to prevent the caking of combustion residues increased. Solid fuel burner according to claim 1, characterized in that the burner tube is surrounded by a flame tube, wherein the oxygen supply takes place via the spacer cavity between the burner and flame tube. Solid fuel burner according to claim 1 or 2, characterized in that in the region of the swirl body, a tubular supply for recirculation air or for exhaust gas recirculation is formed. Solid fuel burner according to one of the preceding claims, characterized in that on the burner tube reaching end of the combustion chamber, a storage area or baffle plate is provided for the retention of the combustible material. Solid fuel burner according to one of the preceding claims, characterized in that in the longitudinal axis direction in the combustion chamber, a rotating shaft with radially oriented arms for Brenngutdurchmischung is located. Solid fuel burner according to one of the preceding claims, characterized in that a Zündföhn or the like ignition arrangement is arranged at the front side Brenngutaufgabebereich the combustion chamber. Solid fuel burner according to one of the preceding claims, characterized in that gasification of the combustible material at temperatures ≤ 800 ° C is introduced in the combustion chamber, wherein by means disposed below the combustion chamber air chambers, the residual oxygen content in the combustion chamber is set to about 6 vol .-% and the air supply the combustion chamber to the air chambers directed openings or openings. Solid fuel burner according to one of the preceding claims, characterized in that the temperature in the precombustion section is set only slightly higher than the temperature in the combustion chamber, wherein in the main combustion section via a further oxygen supply, the temperature to a value between about 1100 ° C to 1300 ° C at λ = approx. 1.4 is set. Solid fuel burner according to one of claims 5 to 8, characterized in that the Brenngutzuführung has a screw conveyor whose drive is coupled to the shaft for Brenngutdurchmischung. Solid fuel burner according to one of the preceding claims, characterized in that a further screw conveyor is provided within the ash discharge.

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