EP0077851B1 - Gas cooling device for a coal gasification plant - Google Patents

Description

The invention relates to a gas cooler arrangement for cooling the reaction products of a coal gasification reactor according to the preamble of claim 1. Such an arrangement is known from DOS 2 933 716. A convective gas cooler shown there is flowed through from top to bottom in one go. Depending on the quality and particle size of the coal to be gasified, only a more or less large part of the ash particles are separated and discharged from the pressure vessel of the first gas cooler, while the rest of the ash particles reach the convective gas cooler. Some of these ash particles settle on the tubes of the tube bundle and for the most part they are discharged from the convective gas cooler with the gas stream. To separate these particles, a special separator is required, which causes an additional pressure drop on the gas side. It is an object of the invention to provide an arrangement in which these disadvantages are avoided. This object is achieved in accordance with the characterizing part of claim 1. Further advantages of the proposed solution also result from the better use of space and from the lower pressure drop of the gases.

The connection of the heat-dissipating tubes to vertical tube panels, that is to say in the direction of flow, prevents the flow cross sections from becoming clogged with ash particles.

Claim 3 takes into account the fact that the risk of clogging the flow cross-section is higher in the downward draft than in the upward draft because the gas contains more ash particles in the downward draft than in the upward draft.

Bypas flows are avoided by the formation of gas-tight walls. The welding of heat-dissipating pipes to pipe walls creates structures that have only a low tendency to vibrate.

By switching the tubes forming welded walls as evaporator tubes according to claim 5, very different temperatures and the associated high thermal stresses are largely avoided.

Claim 6 shows a solution by means of which thermal stresses at connection points of the riser walls on the fall train walls are excluded by avoiding such connection points.

The drop channel through which the cooled medium flows, according to claim 7, brings about an evening of the temperatures in the pressure vessel shell.

Claim 8 is a particularly simple design and manufacturing technology solution.

The meandering arrangement of the pipes in the risers improves the heat transfer coefficient without there being a significant risk of contamination.

However, should contamination occur with extreme coal qualities, the arrangement of pipe cleaning agents according to claim 10 helps.

Claim 11 shows a solution with a good thermodynamic effect and an easy to maintain arrangement.

Claim 12 specifies a particularly easy to operate system.

• Figur 1 einen schematisierten Vertikalschnitt der erfindungsgemässen Gaskühler-Anordnung,
• Figur 2 einen Querschnitt durch den konvektiven Gaskühler nach der Linie 11-11 in Figur 1,
• Figur 3 einen Vertikalschnitt durch einen oberen und einen unteren Höhenbereich des konvektiven Gaskühlers entlang der in Figur 2 eingetragenen, gebrochenen Linie III-III.

The invention will now be explained in more detail using an illustrated embodiment. Show it :

• FIG. 1 shows a schematic vertical section of the gas cooler arrangement according to the invention,
• FIG. 2 shows a cross section through the convective gas cooler along the line 11-11 in FIG. 1,
• 3 shows a vertical section through an upper and a lower height range of the convective gas cooler along the broken line III-III shown in FIG. 2.

FIG. 1 shows a coal gasification reactor 1, to which a circular cylindrical pressure vessel 4 is connected via two nozzles 2, 3 and has an axial drop chamber 6 within a circular cylindrical radiation cooling wall 5. At the lower end of the drop chamber 6, a water bath 8 is provided, which can be washed off via a discharge element 9. Just above the water bath 8, openings are provided in the radiation cooling wall 5, which lead into a riser space 10 delimited by the rear side of the radiation cooling wall 5 and a further cylindrical cooling surface 11. Details of such a pressure vessel with an axial drop chamber and with a water bath are shown, for example, in EP-A-0 048 326 and 0 048 325.

Connected to the cooling surface 11 at the top is a nozzle 14 penetrating the wall of the pressure vessel 4, which leads via a nozzle 15 to a convective gas cooler 20. This gas cooler consists of a pressure vessel 21, which encloses a drop train 23 and - as can be seen in FIG. 2 - two risers 24, 25 and an annular space 26. The fall train 23 and the risers 24, 25 are connected to one another at their lower end by a funnel-like deflection space 28. The lower end 30 of the deflecting space 28, which also serves as an ash collecting space, leads to a closing element (not shown).

As can be seen from FIG. 2, the drop train 23 is limited in horizontal section by two long side walls 32, 33 and two short walls 34, 35, which walls are formed from vertical fin tubes which are welded gas-tight. The fall train is divided into three equal-width chambers by two partition walls 37 and 38, which are also formed from welded fin tubes. The intermediate walls 37 and 38 consist, for example, of fin tubes which are only welded in places and which are each bent out to the side walls 32 and 33 for lateral support and on these can be welded on what is not drawn.

As can be seen from FIGS. 1 and 3, the tubes of the side walls 32, 33 and the walls 34, 35 are connected to a lower distributor 40 and an upper header 41, while the tubes of the intermediate walls 37 and 38 start from a distributor 44 and lead to a collector 45. The collector 41 and the pipes that open into it are spanned in an upper region, in which the pipes are not connected to one another in a gas-tight manner, by a gas-tight hood 47, which is tightly connected all around to the walls 32 to 35 at the level of the collector 45.

The hood 47 is penetrated by lines 48 and 49, which lead from the collectors 41 and 45 to a drum 50 of a steam generator (FIG. 1).

At the bottom of the drum 50, two lines 52, 53 are connected, which lead through the annular space 26 to the distributors 40 and 44 and are provided with pipe loops in the region of their lower ends to accommodate differences in expansion.

On the outer sides of the side walls 32, 33, wall plates 55 and 56, bent in a U-shape, are connected in an approximately gas-tight manner (FIG. 2), by means of which the risers 24, 25 are formed. Three tube sheets 58 and 59 are suspended in each of these risers, which are formed by five meandering tubes each, which extend over the entire, larger horizontal extent of the risers.

The 15 tubes of panels 58 and 59 are each connected at the bottom to a saturated steam distributor 60 or 61, which is connected to the steam chamber of drum 50 via a saturated steam line 62 or 63.

The connector 15 connecting the connector 14 of the pressure vessel 4 to the pressure vessel 21 is connected to the drop cable 23 through the short wall 34. At the lower end of the fall train and the risers 24, 25, sheet metal walls are attached to the walls of these trains along a cross-shaped contour and enclose the deflection space 28.

From the risers 24, 25, pipe sockets 70, 71 lead to internally insulated outlet sockets 72, 74 of the pressure container 21. The sockets 15, 72 and 74 are located in the upper region of the pressure container 21, which is detachably connected to the lower container part via separating flanges 80. As a result, the upper part of the pressure container 21 with the pipe systems attached to it can be lifted up from the lower part.

The upper ends of the tubes forming the tube sheets 58, 59 are connected to a collector 75, which is connected to an axial connection 76, which sits on the pressure vessel 21.

• Das mit Asche- und Schlacketeilchen verunreinigte Gas des Kohlevergasungsreaktors 1 strömt durch den Fallraum 6-von etwa 1450°C auf etwa 1 000 °C sich abkühlend -wobei die Teilchen erstarren und ihre Klebrigkeit verlieren. Die Verunreinigung fallen darauf zum grossen Teil in das Wasserbad 8, wo sie abgeschreckt werden. Der Rest der Verunreinigungen strömt mit dem Gas durch den Steigraum 10 und aus diesem, mit einer Temperatur von beispielsweise 650 °C in den Fallzug 23 des konvektiven Gaskühlers 20.

The system works as follows:

• The gas of the coal gasification reactor 1 contaminated with ash and slag particles flows through the drop chamber 6 - cooling from about 1450 ° C. to about 1000 ° C. - the particles solidify and lose their stickiness. The contaminants then largely fall into the water bath 8, where they are quenched. The rest of the impurities flow with the gas through the riser 10 and out of it, at a temperature of, for example, 650 ° C. into the fall draft 23 of the convective gas cooler 20.

After flowing through the fall train 23, the gas is deflected at a temperature of approximately 450 ° C. into the risers 24, 25, while the majority of the ash and slag particles still present are thrown into the funnel of the deflection chamber 28.

The gas is then cooled further in the risers 24, 25. It then emerges through the connecting pieces 73, 74 from the convective gas cooler 20, be it for direct use as fuel gas or process gas or into a further cooler which can be connected upstream of the drum 50 as an economizer of the steam generator.

The working medium of the steam generator passes from the drum 50 through the lines 52 and 53 into the distributors 40 and 44 and flows from there through the tube walls 32 to 35, at least partially evaporating, and then into the collectors 41, 45 and from there into the Drum 50 back in which water and steam are separated. The working fluid then flows as saturated steam via the lines 62, 63 to the distributors 60 and 61, and from there via the meandering pipes of the tube plates 58 and 59, in which it is overheated, to the collector 75. From this collector it flows to one Reheater or directly for use, be it as motive steam in a thermal power plant or as process steam in a chemical plant.

The invention is not limited to the exemplary embodiment shown in the drawing. For example, the number of tubes of the individual heating surfaces, the ratio of the tubes to the drop train 23 and the risers 24, 25, the number of tube boards 58, 59, the number of chambers, etc. can deviate from the values shown. It may also be expedient to connect the sheet metal walls 55, 56 to the side walls 32, 33 via sliding seals, or to install expansion folds on the sheet metal walls mentioned, or to connect the sheet metal walls 55, 56 around the drop cable 23 so that none Connections to the side walls 32, 33 are necessary. The application of insulation to the sheet metal walls 55, 56 can also be expedient.

The number of ascents is also not limited, although it is advisable to choose a symmetrical arrangement.

While in the relatively wide chambers of the fall train 23, facilities for removing deposits such as sootblowers, ball rain devices and tapping devices can easily be accommodated, it is expedient to provide suitable spaces for such devices in the ascents 24 and 25 between the legs of the meander.

Instead of the sockets 72 and 74 for the Gasau to dispute in the upper part of the pressure container 21, they can also be arranged in the lower part of the container, so that the gas cooled in the risers 24, 25 flows down the annular space 26 and thereby protects the container wall from excessive temperatures.

Claims (12)

1. A gas cooler arrangement for cooling the reaction products of a coal gasification reactor (1), the arrangement having a pressure vessel (4) having an axial fall chamber (6) which has a cylindrical radiation cooling wall (5) parallel to the axis and around which extends an annular rise chamber (10) also bounded by cooling surfaces (11) and connected at the top to at least one convection gas cooler (20) received in a vertical- axis cylindrical pressure vessel (21), characterised in that the convection gas cooler (20) comprises a faller (23) and at least one riser (24) for the gas to be cooled, the faller and riser (23, 24) comprise heat-removing pipes which are components of a vapour generator, and an ash chamber (28) emptyable by way of a closure element and connected to the ends of the faller and riser (23, 24) is provided at the bottom end of the pressure vessel (21).

2. An arrangement according to claim 1, characterised in that the heat-moving pipes of the convection gas cooler (20) are combined, at least in the faller (23), to form vertical tube banks (37, 38).

3. An arrangement according to claim 1 and/or 2. characterised in that the lanes between the tube banks (37, 38) or between discrete tubes (58) are wider in the faller (23) than in the riser (24). 4. An arrangement according to any of claims 1-3. characterised in that the faller (23) and riser (24) are bounded by gas-tight walls (32-34 ; 55) and are in cross-section preferably rectangular.

5. An arrangement according to claim 4, characterised in that the faller walls (32-34) are vertical evaporator tubes of the vapour generator which are welded to one another in gas-tight manner either directly or by way of webs.

6. An arrangement according to claim 4 and/or 5. characterised in that the gas-tight walls (55) of the or each riser (24) extend around those of the faller (23).

7. An arrangement according to any of claims 1-6, characterised in that the walls (55) at least of the riser (24) co-operate with the pressure vessel wall to bound a faller duct through which the medium which has been cooled in the faller and riser flows, protecting the pressure vessel wall from excessive temperatures, to an exit connection in the bottom region of the pressure vessel.

8. An arrangement according to any of claims 1-7, characterised in that the tubes at least either in the faller (23) or riser (24) extend parallel to the axis of the pressure vessel (21).

9. An arrangement according to any of claims 1-8, characterised in that tubes are disposed meanderfashion at least in the risers (24, 25).

10. An arrangement according to claim 9. characterised in that spaces for tube-cleaning means, preferably soot blowers, are left between the meanders or groups thereof.

11. An arrangement according to any of claims 1-10, characterised in that the working medium flows in the faller tubes substantially in countercurrent to the gas to be cooled, the lead-throughs feeding the tubes and for delivery therefrom are disposed near the top end of the pressure vessel, and tube or pipe loops or convolutions are provided near the bottom end of the pressure vessel (21) to take up expansion differences.

12. An arrangement according to any of claims 1-11, characterised in that spigots (15 ; 72) for the entry and exit of gas into and from the faller (23) and riser (24) are disposed in the top part of the pressure vessel (21) and the same has separating flanges (80) below the spigots so that the top pert of the pressure vessel (21) can be lifted off upwardly with the pipe systems secured to it.

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