DE3433238C1 - A process for the fluidised-bed gasification of refuse together with other fuels, and equipment for carrying out the process - Google Patents

Abstract

In a process for the fluidised-bed gasification of refuse with additional fuel, the refuse freed of inorganic material is comminuted after thermal pretreatment and, together with its gaseous reaction products, fed to the fluidised-bed gasification. The refuse is dried by crude gas recycled from the fluidised-bed gasification, and the additional fuel is separately fed to the fluidised-bed in the form of coal or of straw, wood or bagasse treated in the same way. Equipment for carrying out the process consists of an air-tight unit of driers (36, 66) and a mill (38), the fluidised bed gasifier (40) and a comminuter upstream thereof, a fumes gas line (43, 96) leading from the upper offtake of the refuse drier (36) to the inlet (48) of the fluidised-bed gasifier (40), and a crude gas line (41) leading out of the fluidised-bed gasifier (40) being branched into lines leading to the driers (36, 66) for refuse, wood or straw and to the consumers. <IMAGE>

Description

The cross-flow furnace consists of an annular one Treatment room with a vertical inner tube, divided by several closures, which passes through Almost the entire treatment room is enough and with side openings to the treatment room is provided. The negotiation area is surrounded by ring-shaped outer chambers, which are provided with covered openings to the treatment room. The ones from the first drying zone, water vapors drawn off from the treatment room can be used with Advantageously, they can be fed directly to a generator.

DE-OS 23 12350 describes a method for gasifying coal and other carbonaceous solids that are pretreated and stored in a fluidized bed gasification reactor be converted to synthesis gas, which is then methanized. The coal feed is first placed in a pretreatment vessel with a hot, swirling, hydrogen-rich one Product gas from the fluidized bed gasification reactor at temperature between 315-510 "C and high pressure pretreated. The pretreated charcoal and the volatilized components from the pretreated coal are then mixed with steam and in introduced the fluidized bed gasification reactor where the product gas is formed. The dust separated from the product gas of the fluidized bed gasifier is below introduced into these, as well as water vapor and oxygen. The arrears will withdrawn from the gasifier as slag.

From the "Handbook of the Gas Industry", 1940, by H.

Brückner, on pages 2/22 to 2/28 it goes further that with the Winkler gasification ash-rich gasification raw materials can be processed without difficulty, if extensive comminution takes place. Raw lignite is used after pre-drying to 6 to 8% water content, e.g. B. in fire gas dryers, crushed by hammer mills, usually less than 6 mm. Air and oxygen serve as gasification agents and water vapor. There are hardly any hydrocarbons in the product gas. The tangible one The heat of the product gases is used behind the gas generator.

The object of the present invention is to process garbage in this way and to homogenize that he is by a known fluidized bed gasification can be recovered. If possible, they should be cheap and readily available Additional fuels are used.

This object is achieved in that the garbage through from the fluidized bed gasification returned raw gas is dried directly, and that the additional fuel in the form of coal or straw, wood or bagasse treated separately in the same way the fluidized bed is fed separately.

The known fluidized bed gasification has the advantage that it is in one Temperature range from approx. 850 to 11000 C, i.e. in a temperature range around 1000 "C, is carried out. This results in extensive thermal splitting of oil and tars and other chemical compounds. By setting a homogeneous Temperature, a simple product gas spectrum can be maintained.

The raw gas generated in the fluidized bed has a temperature of approx. 850 to 1100 ° C., preferably from 900 to 1000 ° C. Becomes part of this raw gas fed back into the preceding drying stage, this is how the tangible Heat the raw gases a drying of the material, which in the case of recovery of Household waste can contain up to 30% moisture, as well as a pre-gasification of light volatile materials, such as plastics, are not too avoid is. The resulting vapor gases are fed back into the fluidized bed gasifier. The temperature in the drying can be adjusted by adding cold gases, e.g. B. of cooled Raw gas from the fluidized bed gasifier or the downstream waste heat boiler, regulated will. The heating in the drying stage gives the dried material If the elasticity is taken, it becomes highly embrittled, so that it can be easily put in a mill ground to small grain sizes, for example grain sizes of less than 8 mm can be. This material can then be used for fluidized bed gasification, for example via a screw.

It has proven to be particularly advantageous to use the first stage in a so-called cascade mill, which is in the form of an encapsulated garbage cascade mill for throughputs of up to about 100 tons per hour is available.

Depending on the season, there is a high incidence in the harvest time Straw or straw bales. In the other seasons, lumpy wood and the like can be used. attack.

These substances have a relatively high calorific value, some of which is comparable to the calorific value of lignite. The disadvantage is the moisture content, which is why it is necessary to subject these substances to a separate drying process. In particular with lumpy wood, a pre-drying is necessary here because the Water content from pieces of wood is difficult to remove.

Drying is absolutely necessary because it is moist and even air-dry Wood is difficult to grind. Depending on the amount of this biomass is an exclusive one or alternating implementation of the method according to the invention with household waste, commercial waste etc. provided together with wood or straw.

The waste to be processed in the method according to the invention can as additives in addition to air-dry biomass, such as straw, chopped wood, too pre-dewatered sewage sludge or coal may still be added. It has to be proved to be particularly advantageous when adding pre-dewatered sewage sludge, which still have a relatively high water content to add dust to them, that obtained during the dedusting of the second stage, fluidized bed gasification Gas was obtained.

By adding this dry dust, pre-dewatered sewage sludge is obtained a consistency that enables it to be processed further with fine and medium-sized goods, d. H. to be transferred to the mixing bunker and the dryer.

The drying is carried out in a device that has an intensive The hot gases from the fluidized bed gasifier flow onto the material to be dried and thereby enables a good exchange of sensible heat, e.g. B. in one Trough dryer or in a cascade mill. About the unwanted entry of air or to prevent the escape of vapors, the entire drying device, as well as the downstream fluidized bed gasification and the associated pipelines, be hermetically encapsulated.

In the method according to the invention for drying bales of straw The dryer used consists of a horizontal drying room in the side Strohrundballen via a funnel-shaped lock by means of a press disk be pressed in. The lock space is dimensioned so that its diameter is something is smaller than the diameter of the usual straw bales, so that the straw bales compressed when pressed in and so the reaction space close to the atmosphere.

The hot raw gases from the fluidized bed gasifier are fed through nozzles entered directly into the drying room, where their sensible heat is applied directly to the material hand over. Is advantageous z. B. the use of additional lance nozzles. The dried ones embrittled bales of straw then get into a shredding room as the feed continues, Use the rotor flail to shred the pre-degassed bales of straw into straw dust.

The vapor gases with the pulp are fed into the fluidized bed gasifier fed.

A dryer is particularly suitable for drying lumpy wood, in which the hot raw gases the lumpy wood, which from top to bottom through the device is passed through in the cross flow. Such a device exists, for example from an annular treatment room with a vertical inner tube with nozzle-like Openings towards the treatment room, an annular one around the treatment room Outer chamber runs, and concealed between the treatment room and the outer chamber Openings are provided. The treated wood is preferably seamless with a The mill arranged below is crushed to a grain size of less than 8 mm, that the vapor gases are preferably drawn off via a line from a compressor and passed through the mill in such a way that they carry away the crushed wood particles and convey to the fluidized bed gasifier.

The combination of the fluidized bed gasification of waste with its pre-drying offers the various advantages: 1. The fluidized bed gasification is carried out with the vapor gases the pre-drying operated. It can be done either with air or with an air-oxygen mixture as well as with pure oxygen with the addition of other gasifying agents such as carbon dioxide or steam, depending on the intended use of the Gases.

2. Since only the raw gases need to be cleaned, the gas cleaning is very simplified.

3. The thermal reaction steps, i. H. drying and fluidized bed gasification, can be realized in a completely closed system.

The residues, such as ash, ceramics, stones, etc.

are excreted dry via the ash discharge.

4. All garbage becomes one during its thermal degradation Subject to sanitation.

The invention is described below with reference to the drawings explained in more detail F i g. 1 shows a flow diagram for carrying out the method; F i g. 2 shows a longitudinal section through the dryer for straw bales with attached Pipeline; F i g.2A shows a side view of the opened filling chamber Lock; F i g. Figure 2B shows a cross section through the rotor part of the straw dryer; F i g. 2C shows a cross section through the drying room; F i g. 3A shows one Vertical section through the dryer for lumpy wood; F i g. 3B shows an enlarged Section of the outer wall of the treatment room with concealed opening voltages; F i g. 3C shows a cross section through the drying room along the section line A-A the F i g. 3A.

Household waste or similar waste, which is largely inorganic Material are freed, are introduced into the mixing bunker 34. The one in the mixing bunker 34 stored substances are fed via a feeder, for example a rotary valve 35; fed to a dryer 36 with the exclusion of air. Via a raw gas line 42 Raw gases from the fluidized bed gasifier 40 at a temperature of approx.

900 "C to 1000" C introduced into the material contained in the dryer. The water contained in it evaporates due to the high temperature, other substances, such as paper, biomass etc. can be partially degassed and plastics can already be partially degassed be decomposed.

The material thus embrittled is passed through the discharge 37 to a mill 38 fed in with the exclusion of air and ground to a grain size of less than 8 mm. The drying and grinding can advantageously be carried out in a single process stage perform in a cascade mill.

The ground material is then fed into the fluidized bed gasifier via a screw 39 40 registered.

Bales of straw, preferably straw and bales of straw, but also debris, such as pre-dried bagasse and the like.

are fed to a special dryer 66, which is quick and easy good workmanship guaranteed, compare FIG. 2. It is a cylindrical, horizontally arranged dryer, in which in the filling chamber 79 at least one Straw bales are entered, which can be done from the side or from above (see Fig.2a). After closing the flap 83 is with the over the drive 86 and the plunger 85 driven press disk 84 of the bale or bales the funnel-shaped constriction 82 is pressed into the lock 80. Every bale is here compacted so that it acts as a plug. At the next cycle it reaches the drying room 61, in which via the line 42 and the supply pipes 81 and nozzles 87 is hot Raw gases with a temperature of 900-10000C from the fluidized bed gasifier 40 introduced will. In the case of very moist material, lance nozzles 89 can also be used, which are pushed into the bale and which are withdrawn with each cycle. - The bales are pushed through the further cycles, dissolving and releasing Water vapor, CO2, CO, etc., the vapor gases, continue and reach the end of the reactor the rotor flail 91 provided with drive 92, which shreds the material Foreign bodies in the material are hurled into the stone box 95. the The resulting vapor gases are drawn off via line 88 and the fan 90 and blown into the stone box to prevent dust from settling here.

You leave the reactor through sieve trays 94, entraining the comminuted Material into the gas space 93 and are fed to the gas generator 40 via lines 96 and 43 supplied via line 48.

A dryer is best for drying lumpy wood 66a, which consists of an annular treatment space 102 with a vertical inner tube 103 consists, which extends over the entire height of the dryer and above and below is closed, cf.

i g. 3A - C. A "piece of cake" is like a wedge-shaped piece 104 separated from the treatment room 102, through which the gas supply pipes 105 to the inner tube 103. Through this separation is by the way Treatment room 102 a uniform migration of the material from top to bottom guaranteed.

The hot gases are removed from the raw gas line by a compressor 42 are pressed through the gas supply lines 105 into the inner tube 103, where they have a slight Should build up excess pressure. The gases leave through nozzle-like openings 107 the inner tube 103, the material in the treatment room flow transversely, arrow 108 and are covered over openings 109, which are offset from the nozzle-like Openings 107 are made in the outer wall 110 of the treatment room 102, in the annular outer chamber 111 withdrawn. The annular outer chamber 111 surrounds thus the treatment room 102. The outer wall 112 of the outer chamber 111 is at the same time the outside wall of the dryer.

The lumpy wood migrates seamlessly through the treatment room 102 from top to bottom and is ground to dust in mill 118. The vapor gases are withdrawn via line 116 from a compressor, not shown, through the mill 118 and take the wood dust with them. The dust-gas mixture goes through a line 96,43,48 to carburetor 40.

To cool the gases on the outer wall 112 of the annular outer chamber 111, this should be provided with insulation. To the simple To prevent the material from slipping through the treatment room 102 between the inner and outer walls of the treatment room 102 spaced transverse struts 124 built in. These are encased in a rotatable tube. On this pipe you can Cam 123 may be arranged. These cross struts 124 can also go through the central tube 103 are guided and thus carry the entire central tube 103.

The carburetor 40 is a winkler generator. Via the lower line 49 the gasifying agent is introduced. The raw gases are dedusted and can a consumer 50 are supplied.

The dusts obtained during the dedusting 46 of the raw gas 41 can be returned to the fluidized bed gasifier. However, if sewage sludge 98 are available, it has proven to be useful to take them out of the dust extractor 46 originating hot dusts introduced into a mixer 99 via line 97 there to mix with the pre-drained sewage sludge 98. The pre-drained sewage sludge, which are difficult to process because of their consistency can be processed in this way convert into an easily processable mixture. Such dried sewage sludge can then be fed to the mixing bunker 34 via line 100 without further pretreatment will.

- blank page -

Claims (13)

Claims: 1. Process for fluidized bed gasification of waste with additional fuel, with the garbage freed from inorganic material after heat treatment comminuted and added to the fluidized bed with its gs-shaped treatment products is, characterized in - that the garbage by from the fluidized bed gasification returned raw gas is dried directly and - that the additional fuel in Form of coal or straw, wood or bagasse treated separately in the same way the fluidized bed is fed separately. 2. The method according to claim 1, characterized in that the garbage drying is carried out during grinding. 3. The method according to claim 1, characterized in that the bagasse is used pre-dried. 4. The method according to claim 1, characterized in that the drying of lumpy wood takes place in the cross flow and then the pieces of wood on a Particle size of less than 8 mm can be crushed. 5. The method according to claim 1, characterized in that the garbage pre-dewatered sewage sludge is added. 6. The method according to claims 1 and 5, characterized in that that the sewage sludge is mixed with dust separated during the dedusting of the raw gas will. 7. The method according to claim 1, characterized in that the the Drying supplied hot raw gas, cooled raw gas for temperature regulation is admixed. 8. Device for performing the method according to claim 1, consisting from a heat treatment device upstream of the fluidized bed gasifier and a grinder, characterized in that a vapor gas line (43) from upper exhaust of the garbage dryer (36) to the inlet (48) for the additional fuels of the Fluidized bed gasifier (40) leads and one leading out of the fluidized bed gasifier (40) Raw gas line (41) is in lines to the dryer (36, 66) for the garbage, for Straw or wood and branched to the consumer (50) 9. Device according to claim 8, characterized in that the garbage dryer is a mill dryer (38) 10. Device according to claim 8, characterized in that the dryer for straw consists of a horizontally arranged drying room (61), the one in the upflow direction a compression space (80) with a funnel-shaped constriction (82), and an entry space (79) are connected upstream with a flap (83), with a press disk (84) on the side a pressure is generated in the flow direction, and the drying space (61) feed pipes (81) with nozzles (87) for the gasification raw gases and discharge pipes (88), which draw off the vapor gases from the drying room (61) and a crushing room (93) with a rotor flail (91) above a nes stone box (95) to dispense from which they pass straw dust through sieve floors (94) to the fluidized bed gasifier (40) transport. 11. Device according to claim 10, characterized in that in addition Additional, retractable lance nozzles (89) are provided in addition to the nozzles (87). 12. Device according to claim 10, characterized in that the Dryer (66A) for lumpy wood from an annular treatment space (102) with a vertical inner tube (103), which extends over the entire height of the dryer ranges and closed at the top and bottom and with nozzle-like openings (107) for Treatment room (102) is provided, as well as with a treatment room (102) surrounding annular outer chamber (111) with covered openings (109) to the treatment room (102), which is seamlessly connected to a mill (118) arranged below, from which the vapor gases drawn off from the treatment room (102) via a line (116) direct the dried wood to the fluidized bed gasifier (40). 13. Device according to claim 8, characterized in that the The fluidized bed gasifier (40) is followed by a deduster (46), the dust line of which (97) is connected to a mixer (99), where the dust with pre-dewatered sewage sludge (98) is mixed and fed to the garbage bunker (33,34) via a line (100). The present invention relates to a method for fluidized bed gasification of garbage with additional fuel, in which the garbage freed from inorganic material crushed after pre-heat treatment and with its gaseous treatment products the fluidized bed gasification is added. The invention also relates to a device to carry out the procedure. DE-OS 30 04 111 describes a method and an apparatus for the integrated gasification of waste and waste coal with fluidized bed technology. at this process for the fluidized bed gasification of waste with additional fuel, in which the garbage freed from inorganic material is shredded after a pre-heat treatment and added to the fluidized bed gasification with its gaseous reaction products is, the mixture of garbage and coal is first pyrolyzed and crushed and then transferred with the pyrolysis gases into the fluidized bed, the pyrolysis gases mediating special transfer devices are guided into the fluidized bed. The degassed Material resp. the fluidized bed itself can contain additional fuel (sludge) can be added. DE-PS 5 lot 792 describes a grinding-drying of coal, inter alia. for their gassing. The coal is in a mill with constant introduction of Crushed hot gas and on the way from the mill to the separator by introducing it a hot gas and others reheated until degassing. In DE-PS 3 02 322 it is a process for dry distillation, smoldering and gasifying coal in a cross-flow furnace described, wherein the temperature is gradually increased and the distillation products of the individual stages are discharged separately.