DE10159381B4 - steam generator - Google Patents

Abstract

Steam generator (1) with pulverized coal (16), comprising
a vertical and in cross-section substantially rectangular throttle cable (2) having in its lower region a combustion chamber (3) for burning pulverized coal and the ash or slag resulting from the combustion in solid or dry form,
the throttle cable (2) laterally delimiting and substantially vertical and of front and rear walls (4, 5) and side walls (6, 7) formed Umfassungswände and the throttle cable (2) bottom bounding bottom wall (8), wherein the Umfassungswände (4 , 5, 6, 7) and the bottom wall (8) are formed from working medium flow through pipe wall heating surfaces (10),
and wherein the bottom wall (8) is formed with at least three ash outlet openings (9) which extend over their length between the front and rear walls (4, 5) or the two side walls (6, 7).

Description

The The invention relates to a steam generator fired with a pulverized coal is operated, wherein the combustion in the combustion chamber the steam generator resulting ash or slag in solid or dry form is present.

steam generator for the production of energy from fossil fuels are known. It will be common solid fuels, eg. As coal, in the combustion chamber of the steam generator burned. While for steam generators of smaller to medium power grate firing, Fluidized bed combustion or Schmelzfeuerungen for generating the Calorific energy are used in large to largest steam generators exclusively Pulverized coal firing with dry ash removal used. It will the charcoal to be fired is ground into coal dust in milling equipment, fed to the combustion chamber in a direct or indirect manner and by means of suitable coal dust burners in the combustion chamber of the steam generator burned. The released heat is transferred to a working medium, that in the different heating surfaces the steam generator circulates, discharged and by means of the heated Working medium operated, for example, a steam turbine. The at the incineration of coal dust in the combustion chamber resulting ash or combustion residues or are in solid or dry form, with heavier ash particles fall down due to their own weight within the throttle cable and through a deashing opening be deducted from the combustion chamber in the bottom of the throttle cable and lighter Ash particles through the combustion exhaust gas flowing upwards inside the throttle cable or flue gas entrained and thus removed from the steam generator become.

such generic steam generators are inter alia, by the publication "The new 800 MW lignite blocks of the VEAG Vereinigte Energiewerke AG in Boxberg and Schwarze Pumpe ", by M. Kehr, H. Breuer and H. Schettler from VGB Kraftwerkstechnik 73 (1993), Heft 11 become known. As the document, in particular Figure 4 removable is the development of such steam generators in the past Years to ever larger units continued. This raises manifold problems. That's how it is today arrived at steam generators whose combustion chambers have a horizontal cross-section from about 24 × 24 Meters. Such a big one Steam generators need for removal that in a combustion chamber at combustion of the introduced fuel resulting ash a correspondingly large combustion chamber or ash hopper, which is located below the combustion chamber and by the combustion chamber dimensions of the latest Steam generator a height of nearly 20 meters.

These huge funnel heights arise due to the design, because certain inclination angle the funnel walls must be respected to slipping ash. This will increase the overall height of the steam generator disadvantageously to the required funnel height yet enlarged, what the already high investment costs in the steam generator still increases. Such a big one Combustor funnel, for reasons the cooling usually like the combustion chamber walls with tube wall heating surfaces are formed, as they are located far below the burner are only partly due to heat transfer on the in the pipe wall heating surfaces flowing Working medium part. Thus, the efficiency of these funnel wall heating surfaces is a percentage much lower than that of the combustion chamber wall heating surfaces. Further shows disadvantageous that the at an angle inclined combustor funnel walls are susceptible to wear, the falling through the slipping or from the combustion chamber Ash particles and slag pieces is caused.

By publication EP 0 217 079 A1 a steam generator with a pulverized coal firing has become known in which the ashes obtained during combustion are in solid or dry form. The steam generator has a vertical and in cross-section square throttle cable, which terminates at its lower end with a funnel. Funnels and throttle cable are formed from working fluid-carrying tubes, wherein the tubes of the funnel communicate with the tubes of the throttle cable with each other. The funnel has at its lower end a rectangular ash outlet opening, through which a part of the combustion residues arising during the combustion are discharged.

By DE-OS 16 01 310 is a continuous steam generator with a Schmelzkammerfeuerung become known, in which at the Burning ashes in liquid or molten form is present and consequently a to the above and generic coal dust firing deviating firing technology or design training required. For this reason, this known continuous steam generator has in contrast to the generic steam generator in the lower part of the throttle cable several melting chambers, each one Melting chamber over has an ash effluent.

By document DE OS 40 39 463 a steam generating plant has become known, a burner firing and a stationary vortex layer firing. The disposal of incurred in the combustion of the fuel in the combustion chamber and falling falling ash is ensured by a funnel, which connects below the throttle cable or the combustion chamber to this or these and, due to the horizontal cross-sectional dimension of the throttle cable or the Combustion chamber, a large height occupies.

task The invention is now to provide a steam generator, in which the aforementioned disadvantages are avoided.

The The above object is achieved by the features of claim 1 solved.

advantageous Embodiments of the invention are the dependent claims remove.

• – Durch die Ausbildung des Gaszuges eines Dampferzeugers mit einer Bodenwand, die den Gaszug nach unten begrenzt und die mit mindestens drei Ascheaustrittsöffnungen ausgebildet ist, kann auf einen Brennkammertrichter herkömmlicher Art verzichtet werden. Dadurch kann die Bauhöhe des gesamten Dampferzeugers sowie der ihn tragenden Stahlgerüstkonstruktion wesentlich verringert und beträchtliche Investitionskosten eingespart werden.
• – Der untere Abschluß der Dampferzeugerbrennkammer mit der Bodenwand ist infolge der an fast allen Randbereichen vorhandenen Austrittsöffnungen wesentlich verschleißunanfälliger gegen herabfallende Aschepartikel und Schlackebrocken und somit auch wesentlich weniger wartungsbedürftig.

The inventive solution creates a steam generator which has the following advantages:

• - By forming the throttle cable of a steam generator with a bottom wall which limits the throttle cable down and which is formed with at least three ash outlet openings, can be dispensed with a conventional combustion chamber funnel. As a result, the overall height of the entire steam generator as well as the supporting steel framework construction can be substantially reduced and considerable investment costs can be saved.
• - The lower end of the steam generator combustion chamber with the bottom wall is due to the presence of almost all edge areas outlet openings substantially verschleissunanfälliger against falling ash particles and slag dry and thus much less in need of maintenance.

The Ash discharge openings are advantageously formed rectangular. This can be done in easily made the bottom wall forming bottom wall segments and used and provided below the outlet openings ash discharge organs to be ordered.

A advantageous embodiment of the width of the ash outlet openings is 0.3 to 3.0 meters. Here again is for a safe exit of the Ash or slag taken care of. Furthermore, stand for such dimensions different commercial Ash discharge organs available.

Preferably border the long sides the respective outer ash outlet openings on the adjacent enclosure walls of the throttle cable. This makes it possible that from the wall region of the combustion chamber falling ash particles and slag boulders unhindered by a projecting pipe wall through the respective outer ash outlet openings can fall through without causing damage and wear on a pipe wall.

In Advantageous embodiment of the invention are the bottom wall forming and lying between the ash outlet openings bottom wall segments saddlebacked educated. By this configuration is achieved that falling Ashes do not remain lying on the bottom wall segment, but in the outlet opening slip. The saddle-shaped bottom wall segments are in particularly advantageous embodiment with an inclination of at least 45 ° to the Formed horizontal.

In further advantageous embodiment of the invention communicate the Heating surface tubes the bottom wall with the heating surface pipes the surrounding walls, i.e. that the work equipment over the heating surface pipes the bottom wall directly to the heating surface pipes the surrounding walls be supplied can provide without further connecting means.

The Ash discharge openings are in a convenient way arranged parallel to each other. This will make the production of Bottom wall and the arrangement of the ash discharge organs simplified.

below are exemplary embodiments the invention with reference to the drawings and the description explained in more detail.

It shows:

1 schematically shows a steam generator according to a prior art,

2 a horizontal cross section through the steam generator according to section AA of 1 .

3 schematically shows a steam generator according to the invention,

4 a horizontal cross section through the steam generator according to section BB of 3 .

5 a side view of the steam generator according to arrow C of 3 .

6 a partial section of the lower portion of the throttle cable according to detail D of 3

1 and 2 shows a steam generator according to a prior art. The steam generator 1 has a vertical throttle cable 2 and in the lower part of the throttle cable 2 a combustion chamber 3 , The combustion chamber 3 is with a several pulverized coal burner 17 having coal dust firing 16 formed by means of the in the combustion chamber 3 introduced dust-like coal is burned. The throttle cable 2 , which has a rectangular cross section in the flow direction, is laterally of front, rear and two side walls 4 . 5 . 6 . 7 includes or limited. At its lower end is a combustion funnel 11 at the combustion of the fuel in the combustion chamber 3 accumulating and because of their gravity within the throttle cable 2 catching down falling ash particles or slag boils and an ash outlet opening 9 from the combustion chamber 3 rejects them. Below the ash outlet opening 9 For example, either an ash catch grate or a deashing device (both not shown) can be arranged for the removal of the ash.

The surrounding walls of the throttle cable 2 as well as the walls 12 of the funnel 11 are designed as gas-tight pipe walls that serve as heating surfaces 10 serve and in which a working fluid, usually water, steam or a water / steam mixture absorbs part of the heat released during the combustion of the introduced fuel, the working fluid, the tubes of the tube walls 12 . 4 . 5 . 6 and 7 flows through in parallel from bottom to top. The pipe walls are usually formed in pipe-web-pipe connection, but also in rarer cases compounds of special profiles are applied. The heating surfaces of the pipe walls 4 . 5 . 6 . 7 and 12 are usually evaporator, so that the working medium after the flow still superheater heating is supplied before it is supplied to deliver its contained energy, for example, a steam turbine and then possibly reheater heating surfaces. The respective pipes of the walls 4 . 5 . 6 . 7 respectively. 12 can be formed vertically and / or helically wound.

That when burning in the combustion chamber 3 resulting combustion exhaust gas and lighter ash particles that are not down in the combustion chamber funnel 11 fall through the throttle cable 2 headed upwards. The combustion exhaust gas gives a large part of its heat to the pipe wall heating surfaces 10 as well as other, not shown heating surfaces. After passage of the combustion exhaust gas through the throttle cable 2 the exhaust gas is usually at the top of the steam generator 1 deflected and passed over other unillustrated throttle cables to the various exhaust treatment facilities before it passes largely purified in the atmosphere.

Starting from a steam generator 1 according to the above-mentioned prior art according to 1 and 2 has the steam generator according to the invention 1 no continuation of the combustion chamber 3 or the vertical throttle cable 2 down through a funnel 11 but he has a bottom wall 8th on, between the front, back and side walls 4 . 5 . 6 and 7 formed surrounding walls of the throttle cable 2 is arranged and the throttle cable 2 limited below. According to the invention, the bottom wall 8th with at least three ash outlet openings 9 educated. In 3 . 4 . 5 and 6 becomes a steam generator according to the invention 1 shown the four ash outlets 9 in the bottom wall 8th having. The inventive construction, the height of the steam generator according to the invention 1 compared to the height of a conventional steam generator with a comparatively equal horizontal cross section of the throttle cable 2 by a not inconsiderable measure turn out smaller, since at least a large part of the height of the unneeded funnel 11 eliminated. This significantly affects the cost of such a steam generator 1 because not only steam generator tube walls, but also steam generator steel scaffolding, platforms and the like can be saved more by the saving of height.

The ash outlet openings 9 are preferably rectangular and can in their longitudinal direction from side wall to side wall 6 . 7 or from front to rear wall 4 . 5 pass. This allows the respective adjacent perimeter walls 6 . 7 respectively. 4 . 5 can be formed vertically in a simple manner and do not require funnel bends that require costly manufacturing process. The ash outlet openings 9 are arranged in parallel to each other in an advantageous manner, so that the bottom wall 8th Easy to make and the below the openings 9 arranged discharge members (not shown) can also be arranged parallel to each other.

In a preferred embodiment of the invention, the two outer ash outlet openings border 9 with their respective outer longitudinal sides directly to the respective front and rear wall 4 . 5 or to the respective side walls 6 . 7 on, all of which can be formed vertically and therefore production and assembly friendly at its lower end, since no pipe wall kinks must be provided here as well. This has compared to a conventional funnel 11 the great advantage that slag that has accumulated on the combustion chamber walls and, for example, at partial load changes of the steam generator dissolves brockenweise and falls down, no longer fall on the tube walls of a funnel, but unhindered by the side ash outlet openings 9 can fall through and then comes to rest on a discharge member, not shown. Thus, Be Damage to lateral and angled pipe walls can be reliably avoided by slag dry and expensive repair of damaged pipe walls can be omitted.

By training the bottom wall 8th with at least three ash outlet openings 9 is the bottom wall 8th inevitably with at least two, the bottom wall 8th forming, bottom wall segments 13 stocked. These can cause deposits of ash particles from the combustion chamber 3 on the segments 13 to be prevented, trained with appropriate inclinations to the horizontal. This will, as in 3 respectively. 6 best seen through a saddle-shaped design of the bottom wall segments 13 achieved, which prevents the accumulation of ashes as far as possible. In this embodiment, the tubes of the tube wall heating surface 10 the bottom wall segments 13 be arranged advantageously and in a simple manner by the tubes on one side of the saddle-shaped bottom wall segment 13 up and down on the other side. The supply of the working medium happens on the one hand by an inlet collector 14 , which parallel the working medium in the tubes of the tube wall heating surface 10 distributed and the derivative on the other side by an exit collector 15 according to 6 , The inclination of the saddle-shaped bottom wall segments 13 to the horizontal should be at least 45 °, preferably 55 ° or more. In addition to the saddle-shaped formation of the bottom wall 8th However, other constructive solutions are possible. The pipes of the heating surfaces 10 the bottom wall 8th or the bottom wall segments 13 communicate with the pipes of the heating surface 10 the surrounding walls 4 . 5 . 6 . 7 ie that first in the heating surface tubes of the bottom wall segments 13 introduced working medium after passing through these heating surfaces then in the Heizflächen tubes of Umfassungswände 4 . 5 . 6 . 7 arrives.

The outlet opening 9 is advantageous 0.3 to 3.0 meters wide (see 4 and 6 : Width B). At this width (B) is a safe derivative of the combustion chamber 3 down falling ash (bottom ash) guaranteed. Due to the arrangement of ash discharge organs, not shown, such as ash discharge grates, detoxifiers or the like. Below the ash outlet opening 9 The ash to be disposed of can safely be removed while at the same time still being treated (afterburning of burnt material on the grate, cooling on the grate or in the slagger).

As a steam generator 1 All common types of steam generators can be used, ie natural circulation, forced circulation and continuous steam generators, with continuous steam generators predominantly being used for large and largest steam generators.

1

steam generator

2

throttle cable

3

combustion chamber

4

Steam generator bulkhead

5

Steam generator backplane

6

Steam generator sidewall

7

Steam generator sidewall

8th

bottom wall

9

Ash outlet opening

10

Rohrwandheizflächen

11

funnel

12

hopper wall

13

Bottom wall segments

14

inlet header

15

outlet header

16

coal dust

17

Pulverized coal burner

Claims (8)

Steam generator ( 1 ) with pulverized coal firing ( 16 ) comprising a vertical and in cross-section substantially rectangular throttle cable ( 2 ), which in its lower part a combustion chamber ( 3 ) for firing pulverized coal and the ash or slag occurring during combustion is in solid or dry form, the gas flue ( 2 ) laterally limiting and substantially vertical and from front and rear wall ( 4 . 5 ) as well as side walls ( 6 . 7 ) formed surrounding walls and a throttle cable ( 2 ) bottom wall ( 8th ), the surrounding walls ( 4 . 5 . 6 . 7 ) and the bottom wall ( 8th ) from Arbeitsmitteldurchströmten Rohrwandheizflächen ( 10 ) are formed, and wherein the bottom wall ( 8th ) with at least three ash outlet openings ( 9 ) is formed over its length between the front and rear wall ( 4 . 5 ) or the two side walls ( 6 . 7 ). Steam generator according to claim 1, characterized in that the ash outlet opening ( 9 ) is rectangular. Steam generator according to claim 1 or 2, characterized in that the width (B) of the ash outlet opening ( 9 ) Is 0.3 to 3.0 meters. Steam generator according to one of claims 1 to 3, characterized in that the longitudinal sides of the respective outer ash outlet openings ( 9 ) on the adjacent surrounding walls ( 4 . 5 . 6 . 7 ). Steam generator according to one of claims 1 to 4, characterized in that the bottom wall ( 8th ) forming and between the ash outlet openings ( 9 ) lying bottom wall segments ( 13 ) are formed saddle-shaped. Steam generator according to claim 5, characterized in that the inclination of the saddle-shaped bottom wall segments ( 13 ) is at least 45 ° to the horizontal. Steam generator according to one of claims 1 to 6, characterized in that the outlet openings ( 9 ) are arranged parallel to each other. Steam generator according to one of claims 1 to 7, characterized in that the tubes of the tube wall heating surfaces ( 10 ) the bottom wall ( 8th ) with the tubes of the tube wall heating surfaces ( 10 ) of the enclosing walls ( 4 . 5 . 6 . 7 ) are made communicable with each other with respect to working medium flow.