Title of Invention

FLUIDIZED-BED FIRING SYSTEM WITH GENERATION OF STEAM

Abstract

A fluidized-bed firing system with generation of steam for the combustion of solid fuels and for generating steam, characterized in a) that in a heat-exchanger chamber (1) with an inner height of at least 10 meters there are provided heat exchanger elements through which flows a cooling fluid, and the heat-exchanger chamber (1) has four vertical outer walls which enclose a space approximately rectangular in horizontal cross-section, b) that before a first outer wall (la) of the heat-exchanger chamber (1) a first fluidized-bed combustion chamber (2) is provided, and before a second outer wall of the heat-exchanger chamber (1) opposite the first outer wall a second fluidized-bed combustion chamber (3) is provided, where the inner height of the fluidized- bed combustion chambers (2,3) is 10 to 60 m, and each fluidized- bed combustion chamber has lines for supplying fuel and combustion air, and c) that with the upper portion of each fluidized-bed combustion chamber (2,3) there is connected a separator for separating solids from a gas stream, which has a gas-carrying discharge line connected with the upper portion of the heat-exchanger chamber (1).

Full Text

1A Fluidized-bed Firing System with Generation of Steam Description This invention relates to a fluidized-bed firing system with generation of steam for the combustion of solid fuels and for generating steam. Such systems, which are advantageous above all for smaller wattages, are known for instance from EP-B-0365723, EP-A-0416238 as well as DE-A-3107356 and DE-A-4135582. In the known plants, always only one fluidized-bed combustion chamber is associated to a heat-exchanger chamber. For large plants, which produce a large amount of steam that is used in a power plant with more than 250 MW (electrically), the known systems are not advantageous. It is the object underlying the invention to provide the above-mentioned fluidized-bed firing system in a compact design such that it can be built as a block requiring little space. In accordance with the invention this is achieved in - 2 - a) that in a heat-exchanger chamber with an inner height of at least 10 meters there are provided heat exchanger elements through which flows a cooling fluid, and the heat-exchanger chamber has four vertical outer walls which enclose a' space approximately rectangular in horizontal cross-section, b) that before a first outer wall of the heat-exchanger chamber a first fluidized-bed combustion chamber is provided, and before a second outer wall of the heat-exchanger chamber opposite the first outer wall a second fluidized-bed combustion chamber is provided, where the inner height of the fluidized-bed combustion chambers is 10 to 60 m, preferably at least 20 m, and each fluidized-bed combustion chamber has lines for supplying fuel and combustion air, and c) that with the upper portion of each fluidized-bed combustion chamber there is connected at least one separator for separating solids from a gas stream, which has at least one gas-carrying discharge line connected with the heat-exchanger chamber. One embodiment of the invention consists in that to each flu-idized-bed combustion chamber at least one fluidized-bed cooler is associated, which is disposed below a separator and is connected therewith by a line carrying solids, where each fluidized-bed cooler is connected with the associated flu-idized-bed combustion chamber by at least one line carrying solids and/or gas. The plant in accordance with the invention can be designed and built as a compact block. At the same time, it is easily possible to arrange one or more blocks in a space-saving way beside each other with or without a physical separation. Inside a block, the central arrangement of the heat-exchanger - 3- chamber provides for an inexpensive construction due to short lines for the combustion air Introduced into the fluidized-bed combustion chambers, which combustion air is preheated in the heat-exchanger chamber or In some other suitable means. Each fluidized-bed combustion chamber can be connected with the associated fluidized-bed cooler to form a static unit, where the fluidized-bed cooler can be realized in an upright design or suspended at the fluidized-bed combustion chamber. A particularly space-saving design of the firing system is obtained in that the distance between the first fluidized-bed combustion chamber and the first outer wall as well as the distance between the second fluidized-bed combustion chamber and the second outer wall of the heat-exchanger chamber is 0 to 2 m. The firing system in accordance with the invention is designed for big plants. In general, the cross-sectional area of each of the two fluidized-bed combustion chambers, measured horizontally and at half height of the interior of the chamber, will be 50 to 300 m2 and preferably at least 70 m2. Usually, the interior of the first and second fluid feed-bed combustion chambers will be approximately rectangular In horizontal cross-section. For very big plants two or more heat-exchange chambers and atleast three fluidized-bed combustion chambers can be arranged side-by-side alternatingly. Further embodiments will be explained with reference to the accompanying drawings, wherein: Fig. 1 shows a schematical representation of a first variant of the firing system In a longitudinal section along line l-l of Fig.2, Fig. 2 shows a cross-section along line Il-lI of Fig.1, Fig. 3 shows a second variant of the firing system in a representation analogous to Fig.1, and Fig. 4 a big plant with two heat-exchange chambers in a representation analogous to Fig.2. The plant in accordance with Figs. 1 and 2 centrally comprises a heat-exchanger chamber 1 with a rectangular cross- - 4 - section, of. Fig. 2. The four vertical outer walls of the heat-exchanger chamber 1 are designated with the reference numerals 1a, 1b, 1c and 1d. Adjoining the first outer wall la a first fluidized-bed combustion chamber 2 is provided. At the opposite wall 1c a second fluidized-bed combustion cham-ber 3 is provided. To the left fluidized-bed combustion chamber 2 two separators 5 and 6 are connected, and the two separators 7 and 8 correspondingly belong to the right fluidized-bed combustion chamber 3. Each separator has a gas-carrying discharge line 9, which opens in the upper portion of the heat-exchanger chamber 1, cf. Fig. 1. Other than in the drawing, any number of separators may be chosen. As separators, there may for instance be used cyclones known per se or also baffle plates. The solids separated in the separators 5 to 8 are delivered through line 11 to a fluidized-bed cooler 12 or 12a known per se. Details of the fluidized-bed cooler can be taken for instance from EP-B-0365723 and DE-A-4135582. If desired, solids separated in the separator can directly be introduced into the nearest fluidized-bed combustion chamber via a bypass line 11a, as this is represented in the drawing for a better clarity only together with the chamber 3. If fluidized-bed coolers 12 and 12a are completely omitted, the solids coming from the separators are introduced into the fluidized-bed combustion chambers via such bypass lines. Each fluidized-bed cooler is equipped with at least one line 13 for supplying fluidizing gas, e.g. air, it has cooling elements 14 and an outlet 15 for cooled solids. Through the passage 16, part of the cooled solids are introduced into the fluidized-bed combustion chamber 2 together with gas. One variant is illustrated together with the heat exchanger 12a and the fluidized-bed combustion chamber 3, where line 16 supplies cooled solids, and line 17 supplies heated fluidizing gas to the chamber 3. Solid, granular fuels are supplied to the chambers 2 and 3 through the lines 18, and oxygen-containing fluidizing gas, e.g. air, is supplied via line 19, first of all enters a distribution chamber 20 and then flows upwards in the chamber 2 through a grid 21. Further points for supplying gases and solids can easily be provided. Suitable fuels include in particular anthracite coal, hard coal, lignite, wood, or oil shale. In addition to solid fuel there may also be used pasty, liquid or gaseous fuels, e.g. refinery residues or various wastes. The combustion temperatures in the fluidized-bed combustion chambers 2 and 3 lie in the range from 700 to 950°C. A hot gas-solids suspension leaves the fluidized-bed combustion chamber 2 or 3 in the upper portion thereof through an opening 2 3 and flows into the associated separator, in which the solids are largely separated. The hot gases leave the separator through line 9 and are cooled in the heat-exchanger chamber 1. The chamber 1 is equipped with numerous heat-exchanger elements 24 for an indirect cooling of the hot gas, which elements are represented in the drawing only schematically. The elements 24 on the one hand serve to generate steam from boiler feed water, where high-pressure steam with a pressure in the range from 70 to 350 bar and medium-pressure steam with a pressure of 20 to 80 bar can be generated at the same time or alternatively. One or more of the elements 24 can also be used for preheating the air which is then introduced as combustion air into one of the fluidized-bed combustion chambers 2 or 3. The plant is designed for large throughputs, so that the individual parts of the plant have correspondingly large dimensions. The cross-sectional area of the interior of the heat-exchanger chamber 1, measured horizontally at half height of the chamber 1, lies in the range from 150 to 500 m2. For each of the fluidized-bed combustion chambers 2 or 3 the inner . 6- horizontal cross-sectional area, measured at half height above the grid 21, is 50 to 300 m2. The height of a chamber 2 or 3, measured above the grid 21, lies In the range from 20 to 60 m. The horizontal width (a) of the common walls 1a and 1c, of. Fig. 2, is 10 to 40 m. To the firing system, there may be connected a power plant with an electric power of 200 MW or more. To optimally utilize the sensible heat in the firing system, all hot wills may be designed as membrane tubular walls, through which flows a cooling fluid. Cooled gas, which leaves the heat-exchanger chamber 1 through the outlet 25, is supplied to a gas cleaning system not represented here. As already explained in conjunction with Figs. 1 and 2, the plant in accordance with Fig. 3 comprises a central heat-exchanger chamber 1, two fluidized-bed combustion chambers 2 and 3, and separators 5 and 7. The lines 23a connect the fluidized-bed combustion chambers 2 and 3 with the separators 5 and 7. Identical reference numerals as in Figs. 1 and 2 have the meaning stated there. The fluidized-bed combustion chambers in accordance with Fig. 3 have a downwardly wedge-shaped design. In the plant in accordance with Fig. 3, there is a distance of not mote than 2 m between the outer wall 1a of the heat-exchanger chamber 1 and the fluidized-bed combustion chamber 2, in which distance line 11 is passed through to the fluidized-bed cooler 12, The same distance also exists between the wall 1c and the fluidized-bed combustion chamber 3. Since the separators 5 and 7 are disposed above the chambers 2 and 3, the block is high and requires little ground area. In the big plant shown schematically in a horizontal view in Fig. 4, two heat exchange chambers 1 and 3 fluidized-bed combustion chambers 2, 3 and 4 are put side-by-side alternatingly. The separators have numerate 5 to 8. Alternative to the row arrangement shown In Flg.4, the chambers may be arranged together with further heat exchange chambers and/or fluidized-bed combustion chambers to form altogether a cross, an L or T in a horizontal view. -7-We Claim: 1. A fluidized-bed firing system with generation of steam for the combustion of solid fuels and for generating steam, characterized in a) that in a heat-exchanger chamber (1) with an inner height of at least 10 meters there are provided heat exchanger elements through which flows a cooling fluid, and the heat-exchanger chamber (1) has four vertical outer walls which enclose a space approximately rectangular in horizontal cross-section, b) that before a first outer wall (la) of the heat-exchanger chamber (1) a first fluidized-bed combustion chamber (2) is provided, and before a second outer wall of the heat-exchanger chamber (1) opposite the First outer wall a second fluidized-bed combustion chamber (3) is provided, where the inner height of the fluidized-bed combustion chambers (2,3) is 10 to 60 m, and each fluidized-bed combustion chamber has lines for supplying fuel and combustion air, and c) that with the upper portion of each fluidized-bed combustion chamber (2,3) there is connected a separator for separating solids from a gas stream, which has a gas-carrying discharge line connected with the upper portion of the heat-exchanger chamber 2. The fluidized-bed firing system as claimed in claim 1, wherein to each fluidized-bed combustion chamber a fluidized-bed cooler (12, 12a) is associated, which is disposed below a separator and is connected therewith by a line carrying solids, where each fluidized- bed cooler is connected with the associated fluidized-bed combustion chamber by a line carrying solids and/or gas. 8 3. The fluidized-bed firing system as claimed in claims 1 or 2, wherein the distance between the first fluidized-bed combustion chamber and the first outer wall as well as the distance between the second fluidized-bed combustion chamber and the second outer wall of the heat-exchanger chamber is 0 to 2 m. 4. The fluidized-bed firing system as claimed in claims 1, 2 or 3, wherein the cross-sectional area of each of the two fluidized-bed combustion chambers (2,3) is 50 to 300 m2, measured horizontally and at half height of the interior of the chamber. 5. The fluidized-bed firing system as claimed in claim I or one of the preceding claims, wherein the interior of the first and second fluidized-bed combustion chamber (3) is approximately rectangular in horizontal cross-section. 6. The fluidized-bed firing system as claimed in claim 1, or any of the preceding claims, wherein the heat-exchanger chamber (1) and the fluidized-bed combustion chambers (2,3) have a width (a) of 10 to 40 m. 7. The fluidized-bed firing system as claimed in claim 1 or any of the preceding claims, wherein two heat exchange chambers and three fluidized-bed combustion chambers are arranged together. (S BANERJEE) of LSDAVAR & CO. Applicants' Agent. Dated this 25th day of AUGUST 1998. A fluidized-bed firing system with generation of steam for the combustion of solid fuels and for generating steam, characterized in a) that in a heat-exchanger chamber (1) with an inner height of at least 10 meters there are provided heat exchanger elements through which flows a cooling fluid, and the heat-exchanger chamber (1) has four vertical outer walls which enclose a space approximately rectangular in horizontal cross-section, b) that before a first outer wall (la) of the heat-exchanger chamber (1) a first fluidized-bed combustion chamber (2) is provided, and before a second outer wall of the heat-exchanger chamber (1) opposite the first outer wall a second fluidized-bed combustion chamber (3) is provided, where the inner height of the fluidized- bed combustion chambers (2,3) is 10 to 60 m, and each fluidized- bed combustion chamber has lines for supplying fuel and combustion air, and c) that with the upper portion of each fluidized-bed combustion chamber (2,3) there is connected a separator for separating solids from a gas stream, which has a gas-carrying discharge line connected with the upper portion of the heat-exchanger chamber (1).

Documents:

01523-cal-1998-abstract.pdf

01523-cal-1998-claims.pdf

01523-cal-1998-correspondence.pdf

01523-cal-1998-description(complete).pdf

01523-cal-1998-drawings.pdf

01523-cal-1998-form-1.pdf

01523-cal-1998-form-2.pdf

01523-cal-1998-form-3.pdf

01523-cal-1998-form-5.pdf

01523-cal-1998-g.p.a.pdf

01523-cal-1998-priority document others.pdf

01523-cal-1998-priority document.pdf

1523-CAL-1998-(05-06-2012)-ASSIGNMENT.pdf

1523-CAL-1998-(05-06-2012)-CORRESPONDENCE.pdf

1523-CAL-1998-(05-06-2012)-OTHERS.pdf

1523-CAL-1998-(05-06-2012)-PA-CERTIFIED COPIES.pdf

1523-CAL-1998-(05-06-2012)-PETITION UNDER RULE 137.pdf

1523-CAL-1998-CERTIFIED COPIES(OTHER COUNTRIES).pdf

1523-CAL-1998-CORRESPONDENCE.pdf

1523-CAL-1998-ENGLISH TRANSLATION.pdf

1523-CAL-1998-For Alteration Of Entry In The Patent Register-1.1.pdf

1523-CAL-1998-For Alteration Of Entry In The Patent Register.pdf

1523-CAL-1998-FORM-27.pdf

1523-cal-1998-granted-abstract.pdf

1523-cal-1998-granted-claims.pdf

1523-cal-1998-granted-correspondence.pdf

1523-cal-1998-granted-description (complete).pdf

1523-cal-1998-granted-drawings.pdf

1523-cal-1998-granted-examination report.pdf

1523-cal-1998-granted-form 1.pdf

1523-cal-1998-granted-form 2.pdf

1523-cal-1998-granted-form 3.pdf

1523-cal-1998-granted-form 5.pdf

1523-cal-1998-granted-gpa.pdf

1523-cal-1998-granted-letter patent.pdf

1523-cal-1998-granted-priority document.pdf

1523-cal-1998-granted-reply to examination report.pdf

1523-cal-1998-granted-specification.pdf

1523-cal-1998-granted-translated copy of priority document.pdf

1523-CAL-1998-PA.pdf