DE2611949A1 - Coal gasification plant - having radiant tube flue with hydraulic and thermal cleaning preceding waste heat recovery - Google Patents

Abstract

In a coal gasification plant, operating at >900 degrees C the synthesis gas is cooled down in a waste heat recovery plant. The latter is preceded by a radiant tube flue with a hydraulic and thermal cleaning system which ca be lifted in and out of a water bath. This solidifies the slog in the radiant tube flue and prevents clogging of the following convection heating surfaces. The continuous cleaning of the flue prevents any undue rise of the upstream gas temp.

Description

NCOAL SHAVING SYSTEMS

The invention relates to a system for gasifying coal at over 9000C with subsequent cooling of the synthesis gas in a waste heat plant.

At a gasification temperature above 9000C the synthesis gas takes a As the gasification temperature increases, the amount of ash or slag increases with. The slag is liquid and sticky and must solidify; otherwise pollute the convection heating surfaces of the downstream waste heat system and the Waste heat system in the shortest possible time. In order to solidify the slag, operated you can look at different procedures, either a corresponding amount of water is in the Synthesis gas is injected or cold gas from the system is converted into the hot raw gas injected, i.e. the synthesis gas is recirculated. Quenching the slag with water has the disadvantage of high heat loss during use of cold gas requires significant investment for the fan.

The invention is therefore based on the object of a gasification plant to create in which the synthesis gas without great heat loss with little structural Effort on one temperature is cooled from about 900 to 9500C, in which the ash and slag particles are in solid form and thus in a downstream waste heat system no longer contaminate the convection heating surfaces or can stick.

The invention is based on the idea of convection heating surfaces upstream of the waste heat system a radiant train, on whose heating surfaces the from The slag carried along by the synthesis gas partially solidifies, at the same time it is through constant cleaning of the radiation train an unacceptable increase in the gas temperature in front of the convection heating surfaces prevented0 However, when cleaning the radiation train has some problems. So the cleaning system must be at a temperature work from 900 to 14500C and withstand this temperature during breaks in operation. It should also be taken into account that the gas pressure is 25 to 60 bar and the synthesis gas toxic or toxic in particular with carbon monoxide, hydrogen sulfide and hydrogen Contains ignitable components. The invention contributes to this through a radiation train arranged hydraulically and thermally working cleaning system bill that is under water during breaks in operation. As a result of permanent arrangement of the cleaning system there are no sealing problems in the radiation flux. The dangerous ones under pressure Components of the synthesis gas cannot escape to the outside during cleaning. aside from that is the cleaning system against the effects of heat during breaks in operation below the water level and slag protected.

The thermal and hydraulic processing of the slag is guaranteed always an optimal cleaning. The one adhering to the heating surfaces of the radiant train When the water hits the hot slag, it suddenly contracts stronger Brought cooling, that has cracking and flaking the slag layer result. The detachment of the slag is done by the mechanical Increase the force of the water penetrating the cracks and under the slag layer, At the same time, the water pressure causes intensive contact with the slag layer and thus a better thermal effect, the water is from one, preferably sprayed against the slag layer from several cleaning nozzles the cleaning system is particularly effective when initially against the slag layer on the discharge side is sprayed where it is thickest is, and the cleaning nozzles then to the entry-side end of the slag layer be moved. Accordingly, at least one is against different heating surfaces of the radiation train movable cleaning nozzle and / or are several against different Cleaning nozzles directed and operated one after the other Provided0 The cleaning nozzles can also be designed to be movable in order to move them over to be able to raise the water level. This prevents the water jet from being affected Steamed water bath of the radiation train. The same can be done with a lowering of the water level. After lowering the water level, there are some wall surfaces of the water bath tank exposed to the heat radiation of the synthesis gas, which previously were protected by the water bath. To damage these wall surfaces too prevent, they are provided with cooling boxes.

Instead of the cooling boxes, other cooling devices can also be used will.

In addition to lifting out of the water bath and / or steering the Water jet it serving lifting movement of the cleaning nozzles, the rectilinear or as a rotary movement, the cleaning nozzles can be rotated in Circumferential direction of the radiation train advantageous. This rotatability allows one Cleaning movement in the circumferential direction.

With fixed nozzles, the can be moved from the boiler discharge side to the boiler inlet side Achieve going cleaning movement that first the against the discharge side Boiler heating surfaces directed nozzle and then the other cleaning nozzles accordingly their position are operated one after the other.

In a further embodiment of the invention, the amount is injected Cleaning water per unit of time upwards through the water vapor partial pressure in the Syngas limited at which the corresponding dew point temperature of the syngas it is 50 0C above the lowest heating surface temperature. That prevents a Precipitation of the condensable components of the synthesis gas due to excessive Cooling on the heating surfaces and thus their soiling. The limitation of the amount of cleaning water can regardless of the fuel used for the gasification according to the respective gasification conditions. Even with relatively low allowances The amount of cleaning water is obtained by increasing the water pressure to at least 100 bar and up to 600 bar still a sufficient cleaning effect. Simultaneously the permissible amount of cleaning water is adhered to with step-by-step cleaning. This means that the heating surfaces of the radiant pass are exposed to water at intervals.

Otherwise, the synthesis gas is deflected in the jet of rays a considerable pre-separation of ash or slag because the ash or slag Slag particles escape from the gas flow due to their inertia and into the Water bath fall.

So that the slag particles are immediately in the water bath of the radiation train collect, the synthesis gas is introduced into the radiation flue that the water level forms the baffle of the deflection point in the radiation train for the synthesis gas, The mechanical partial cleaning of the synthesis gas by deflecting and solidifying the Slag in the radiant flue in front of the convection heating surfaces of the waste heat plant continually. The cleaning of the heating surfaces of the radiant train always starts then on, if the synthesis gas temperature at the discharge end of the radiation pass 950 0C reached, so that the contamination of the downstream convection heating surfaces dominate.

The invention is illustrated below with reference to two in the drawing Embodiments of the explained in more detail. They show: FIG. 1 a schematic View of a coal gasification plant according to the invention and FIG. 2 shows a detail a further cabbage gasification plant according to the invention.

The gasification plant consists of a reactor 1, which is through an opening 2 coal is fed. The coal is fed into the reactor 1 with the aid of Oxygen and water vapor are gasified. The synthesis gas occurs after leaving the reactor 1 with a temperature of 1400 and 14500C in a radiation flue 3 of the waste heat plant, which it leaves again at a temperature of 900 to 950 0C to be transferred to downstream Convection heating surfaces of the waste heat system to be further removed.

During the cooling of the synthesis gas, those from the synthesis gas solidify from the reactor 1 entrained slag particles on the heating surfaces forming Cooling tubes 4 of the radiation train 3; however, most of it solidifies in the synthesis gas stream and is carried along by the gas stream as dry, dusty and no longer sticky ash0 Heavy ash particles fall into a water bath 5 of the radiation train because of the synthesis gas flow is deflected at the water level to the discharge opening 6 of the radiation train 3 and the slag particles remain in their trajectory due to their inertia.

As the operating time progresses, the layer of slag is attached to the Cooling tubes 4 getting thicker. Since the slag layer has a heat-insulating effect, that has a reduction in the cooling effect and an increase in the synthesis gas temperature the outlet opening 6 result. The gas temperature at the outlet opening 6 is by a thermometer, not shown, protruding into the gas stream, preferably a thermocouple. The thermocouple is coupled to a switching device, which when reaching a temperature of 950 0C either an acoustic and / or optical display device operated or the cleaning device automatically sets in motion.

The cleaning device includes several close to one another in the middle Cleaning nozzles 7 arranged in the radiation train 3. The arrangement can be fixed or in way not shown, for example, with the help of trusses, bearings and a common rotary drive be designed to be rotatable. A Serve hydraulic motor, which acts through a gear on all cleaning nozzles and through with a feed line from a hydraulic pump arranged outside the radiation train Pressure fluid is fed from the three cleaning nozzles 7 shown one on the lower part of the Cooling tubes 4, the second on the middle one Part and the third directed towards the upper part of the cooling tubes, before commissioning all cleaning nozzles 7 and their accessories are below the water level. When commissioning, the water level is first of the water level marked 8 lowered to the water level 9 before the cleaning nozzles 7 acted upon with water After lowering the water level, the exposed wall surface is the Water bath housing exposed to high levels of heat; it is therefore with cold boxes 10 provided to protect the boiler wall, for example in the feed water preheating or another water cycle are involved.

The actual cleaning of the cooling tubes 4 begins with the start-up the cleaning nozzle 7 directed at the lower pipe part Cleaning nozzle 7 is the boiler wall from a large number of nozzle bores on the circumference sprayed evenly with water at a pressure of 400 to 600 bar. A rotatable one In contrast to a fixed, cleaning nozzle has only a few openings or only a single, for example, slit-like opening from which a jet of water with the same pressure emerges which covers the entire height of the surface to be cleaned and moved along the boiler wall in the circumferential direction by turning the cleaning nozzle wird0 The layer of slag that flakes off and breaks off when the boiler wall is sprayed collects under the cleaning nozzles 7 in the water bath 5.

After cleaning the lower part of the cooling tubes 4, cleaning follows of the adjoining middle pipe part. This happens in the same way as the cleaning of the lower part of the pipe by starting the pipe on the middle part directed Cleaning nozzle 7. After cleaning the In the middle part of the pipe, the cleaning nozzle is directed towards the upper part of the pipe actuated.

The water bath of the radiation train exercises the water vapor partial pressure of the synthesis gas has no technical effect. On the other hand, it increases when spraying water the water vapor partial pressure is very strong, the associated risk of falling below the dew point of the synthesis gas is released by actuating the cleaning nozzles individually 7, which are provided with separate feed lines 11 for this purpose the cleaning nozzles for extremely low and previously specified permissible water quantities actuated per unit of time in short or longer intervals, so that only Blasts of water come out of the cleaning nozzles 7. Since the cleaning takes a long time There are limits, a longer cleaning time is without disadvantage. As far as the Cleaning is controlled by hand, all that is required is a simple slide in the supply lines 11. The cleaning nozzles 7 can be followed by the operators View through different viewing holes 12 can be observed.

After cleaning is finished, the water level will return to the Water level 8 raised.

The coal gasification plant according to Figo 2 differs from that according to Figo 1 by a constant water level and one for commissioning the water level can be raised or

Cleaning nozzle that can be lowered below the water level after cleaning 13. A power piston 14, the cylinder of which is attached to the radiation train, serves as the lifting device 3 is attached and its piston via a piston rod 15, the cleaning nozzle 13 emotional.

The piston stroke can be designed so that it is sufficient to the On the other hand, cleaning nozzle 13 is to be fed along the heating surfaces of the radiation train 3 is also a cleaning with one just above the water level raised cleaning nozzle 13 possible if this has a sufficient number of holes has to apply water to all heating surfaces.

The cleaning nozzle gets the water through the hollow piston rod 15 fed. The actuation of the power piston 14 and the water supply can thereby be connected to each other by the hydraulic fluid used for power piston actuation Opportunity is given through a piston bore in the piston rod bore and the cleaning nozzle 13 to escape.

The slag collected at the bottom of the radiation train 3 is discharged during discharge from the radiation train 3 first brought into a lock 16, which after filling of slag can be closed tightly against the radiation flue 3 and so discharging of slag from the radiation train 3 without a pressure drop in the radiation train 3.

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Claims (1)

Claims: 1. Plant for gasifying coal at over 9000C with subsequent cooling of the synthesis gas in a waste heat plant, g e k e n n z e i c h n e t d u r c h a radiation train upstream of the waste heat plant (3) with a hydraulic and thermal cleaning system (7, 13) o 2nd system according to claim 1, that the cleaning system (7, 13) is arranged in a water bath so that it can be raised and lowered. 3 * system according to claim 1, d u r c h g e n n n -z e i c h n e t that the water level (8) can be lowered below the cleaning system. 4. Plant according to claim 3, d a d u r c h g e k e n n -z e i c h n e t that the wall surfaces freed by lowering the water level (8) with a cooling device (10) are provided. 5. Plant according to one or more of claims 1 to 4, d a d u notices that the cleaning system is at least one against different heating surfaces of the radiation train (3) movable cleaning nozzle (7, 13) and / or several directed against different heating surfaces of the waste heat boiler and has individually controlled cleaning nozzles (7). 6. Plant according to claim 5, d a d u r c h g e k e n n -z e i c h n e t that the movable cleaning nozzle (7) is rotatable. 7. Plant according to claim 5 or 6, d a d u r c h g e -k e n n z e i c h n e t that the movable cleaning nozzle (7, 13) at the start of cleaning against the discharge-side heating surfaces of the radiation train (3) is directed and the cleaning movement runs to the entrance side of the radiation train (3). 8. Cleaning method for a plant according to one or more of the Claims 5 to 7, that of several Cleaning nozzles at the start of cleaning against the heating surfaces on the discharge side of the jet directed nozzle is actuated first and the remaining cleaning nozzles according to the location of their associated cleaning surfaces for one on the entrance side of the radiation train ongoing cleaning can be operated. 9. The method according to claim 8, d a d u r c h g e k e n n -z e i c h n e t that the amount of cleaning water injected per unit of time according to is limited above by the water vapor partial pressure in the synthesis gas at which the corresponding dew point temperature of the synthesis gas 500C above the lowest Heating surface temperature is. 10. The method according to claim 9, d a d u r c h g e k e n n -z e i c N e t that the water pressure of the cleaning nozzles is at least 100 bar. 11. The method according to claim 10, d a d u r c h g e k e n n -z e i c n e t that the water pressure is between 400 and 600 bar, 12th Method according to one or more of Claims 8 to 10, d a d u r c h g e k e It is noted that the cleaning nozzles are used for a single cleaning process operated at intervals. 13. The method according to one or more of claims 8 to 12, d a it is indicated that the cleaning system is dependent on is actuated by the discharge temperature of the synthesis gas. 14. The method according to claim 13, d a d u r c h g e k e n n -z e i c Note that the actuation temperature is 9500C.