DE3529740C1 - Process and equipment for gasifying carbonaceous wastes, if appropriate with addition of toxic and highly toxic wastes, to give synthesis gas - Google Patents

Abstract

In a process for gasifying carbonaceous wastes, biomasses and also hazardous wastes, if appropriate with addition of toxic and highly toxic wastes, to give synthesis gas, the substances to be gasified are, together with a crude gas part stream recycled from an iron bath reactor, subjected to a pyrolysis at temperatures from about 400 to 1100 DEG C in a fluidised-bed reactor. Pyrolysis coke comminuted to about 0 to 3 mm and, if necessary, further heat generator is added to the pyrolysis gas containing the fine pyrolysis coke and the mixture is passed into an iron bath reactor, which is fed with oxygen as oxidising agent. Toxic or highly toxic substances can be charged to the fluidised-bed pyrolysis or, if they cannot be processed therein, can be added to the gas stream fed to the iron bath reactor. The equipment for carrying out the process consists of a combination of a fluidised-bed reactor 10 with an iron bath reactor 71. The melting vessel contains a plinth 75 in which the nozzles for introducing pyrolysis gas, oxygen and loaded solids are arranged at an angle relative to one another. <IMAGE>

Description

The present invention relates to a method for ver gases from carbonaceous wastes, largely from inorganic materials are exempt, and those with hot, Product gas of a Py recirculated from the gasification process rolysis treatment at temperatures of 400-1100 ° C then crushed and together with additional firing substances (heat generators) and in pyrolysis treatment resulting gases are gasified with the addition of oxygen. The invention further relates to a device for Execution of the process with a molten iron bath generator with fuel and gasification agent conditions below the bath surface.

DE-OS 32 12 534 describes a process for gasification of household waste and similar waste where in which it is cut to a particle size of at least 50 mm Gasified material in compressed form into a Molten iron below the surface of the iron melt is pressed in and as an oxidizing agent Air, oxygen, water or mixtures thereof be taken, the temperature of the molten iron is maintained at about 1130 to 1500 ° C. The procedure has the disadvantage that the energy supply via the Gasification material is difficult to control.  

A process is also described in DE-PS 34 33 238, in the garbage with coal and oxygen etc., in a we Bed-layer furnace gasified and with recirculated raw gases Biomass pre-dried, shredded and gasified the.

The object of the present invention is to create an egg nes process for the recycling of carbonaceous Waste, biomass and special waste with which also toxic and highly toxic substances environmentally friendly and have it processed economically into synthesis gas.

This object is achieved in that the pyrolysis of the wastes comminuted to less than 9 mm takes place in a fluidized bed together with additional fuel, for this purpose O ₂ and / or CO _{2 is introduced} for temperature control, acid-binding agents (lime, dolomite) are added to the fluidized bed, the pyrolysis coke is reduced to less than 3 mm, the pyrolysis coke with the addition of known heat toners (high-temperature coke, Al, Si, P) and with most of the pyrolysis gas is introduced together with oxygen into an iron bath reactor, the remaining pyrolysis gas with an acid-binding agent (Lime, dolomite) of 0-3 mm grain size and ge is entered separately in the iron bath reactor that the iron bath reactor is continuously added under 30 mm of shredded scrap and, accordingly, melt is discontinuously drawn off, that is toxic in the pyrolysis treatment and / or in gasification Fabrics are used.

The substances to be gasified are first Line around household waste, waste similar to household waste, also around Son der Waste such. B. sludge, sewage sludge and the like., which can also be toxic, as well as dry biomas that are not chemically bonded until the removal of the which water is dried, such as B. wood, straw, Bagasse etc. As buffer material and additional coal Dry coal is added to the material supplier, e.g. B. in Form of hard coal, lignite, peat, etc., the material used in the pyrolysis at least a grain size of about 0-9 mm can be crushed should.

The pyrolysis in the fluidized bed is preferably at Temperatures of around 600-900 ° C are carried out. Doing so expediently applied a pressure of about 1-20 bar, where it has proven to be particularly favorable, the Pyrolysis at an excess pressure of about 3-8 bar to take.

The temperature in the fluidized bed pyrolysis can be influenced by suitable control means. If the temperature is too low, oxygen can be added; if the temperature is too high, the temperature can be lowered by adding CO ₂ .

The fluidized bed can be toxic or highly toxic in liquid, gaseous or pasty form or in solid ter form in a grain size of about 0-9 mm supplied will. They can be in particular in the form of liquid pasty sludges, also with mineral oil waste, such as B. Waste oil or other waste hydrocarbons into which we can be injected.

Toxic or highly toxic substances in the fluidized bed cannot be processed, as will come in later which is described, the fed to the iron bath reactor Gas streams are added, preferably in pre-dried Shape.

To bind acidic substances it is necessary to use the Fluid bed acid-binding substances, such as Calcium carbonate, dolomite, calcium hydroxide, NaOH, KOH, or the like. Calcium carbonate or dolomite preferably used.

An endothermic reaction takes place in the fluidized bed, whereby as reaction products pyrolysis gas, pyrolysis fine coke and pyrolysis coke. It has to be an allother heat reaction are supplied from the outside, what is felt by the warmth of the following Stage of the iron bath reactor recycled product gas part current is effected. These hot gases have when they do approx. 1400-1600 ° C hot iron bath leave a large one Heat content through which the allothermic pyrolysis reaction is made possible.

The gases leaving fluidized bed pyrolysis and the a large part of the coal contained in the gasification material Contain in the form of pyrolysis fine coke are in  split two sub-streams. A larger partial flow that than Carrier gas acts, it becomes in fluid bed pyrolysis holding residues made of pyrolysis coke and inert material consist, and which are finely ground, mixed. Except this is in accordance with the heat requirement of the iron bath first heater in the form of high temperature coke in the Py rolysegasstrom entered. Furthermore, a second heat metal, for example aluminum, silicon or phosphorus, be added to the pyrolysis gas stream as required, wherein e.g. B. phosphorus is added when one of the Thomas slag similar product obtained as a fertilizer shall be.

A smaller sub-stream of pyrolysis gases, which without remains, is fed into the iron bath and serves as a cooling or protective gas for those fed into the iron bath Oxygen to prevent local overheating of the iron bath avoid.

The pyrolysis gases, to which high-temperature coke and possibly a second heating element have been added, reach the iron bath together with oxygen, in which molten pig iron is kept at a temperature of around 1400-1600 ° C. The heat energy required for maintaining the melting temperature is supplied by the coke supplied in the pyrolysis gases, namely by the pyrolysis coke coming from the fluidized bed pyrolysis and the optionally additionally supplied heat toners. If the temperature drops sharply in the molten iron, as can occur, for example, because the water content of the pyrolysis gases is too high and the proportion of inert material in the pyrolysis coke is too high, additional heat energy must be supplied to the iron bath. If the temperature in the molten iron increases too much, the temperature can be controlled, for example, by adding CO ₂ .

Since the pyrolysis gases supplied to the molten iron generally contain acidic substances, it is necessary to use the oxygen flow, which is called Carrier gas acts to add acid-binding substances. This acid binding substances can be the same as those which are added to the fluidized bed pyrolysis.

The oxygen flow can be toxic or highly toxic substances Fe are added, which are essentially in the form of dusts are present. This method is particularly suitable for the recycling or destruction of highly toxic dioxin or furan containing substances or dusts, the highly toxic substances are broken down molecularly in an iron bath, d. H. the molecules of the highly toxic substances become too small nere not or less toxic fragments broken down.

The molten pig iron is discontinuously made from the iron Bad tapped, the iron bath continuously scrap is added. This creates an accumulation of harm Lichen components such as copper, arsenic or Tin avoided as much as possible. However, it is an advantage liable if the iron bath harmful substances if possible be kept away from the production of inferior Limit pig iron if possible.

The product gas emerging from the iron bath mainly consists of CO and has a temperature of approx. 1200-1500 ° C. If superheated steam is added to this product gas, a conversion or partial conversion takes place without the addition of a catalyst. By metering the amount of steam, the desired ratio of CO, CO ₂ and H ₂ in the synthesis gas can be set.

The device for carrying out the method according to the invention consists of an iron bath generator which is a known fluidized bed pyrolysis reactor ( 10 ) with line ( 24 ) for additional fuel, outlet ( 41 ) for the dust-laden pyrolysis gas, from order ( 36 ) for pyrolysis coke, upstream whose gas line ( 51 ) are closed as delivery lines for its pyrolysis gas products to the iron bath generator ( 71 ), while it is connected at the bottom with a return line ( 57 ) for product gas recirculated from the iron bath reactor ( 71 ) and the melt pool vessel below the melting level ( 74 ) all around, a slightly sloping console ( 75 ) forming refractory material ( 76 ) is issued, through which at least one pair of nozzles ( 81 and 82 ) extends, which end with their mouths with the vertical wall of the console ( 75 ) and the nozzles are each at such an angle to one another that their axis intersection ( 9th ) 100-400 mm preferably 200 mm are in the melt pool ( 83 ), a nozzle ( 82 ) being two-pipe, the inner channel of which is connected to the oxygen supply and the outer channel of which is connected to the pyrolysis gas supply, while the second nozzle ( 81 ) single-pipe and connected to the supply of the carrier gas loaded with Pyro lysekoks. The console protects the nozzles against mechanical and thermal effects and thereby increases their service life, so that a renewal during the normal operating time of the iron bath reactor is generally not necessary.

The nozzles are at an angle to each other that is approximately 70 to 90 ° and preferably about 90 °. The Intersection of the angle is about 100-400 mm in that Inside the melting bed, preferably lies  the intersection of the angles, from the wall of the enamel counted about 200 mm within the enamel bed. The mouth of the two nozzles is about 100- 400 mm, preferably about 200 mm, above the bath sole.

One of the nozzles is designed as a two-tube nozzle, the inner channel for the supply of oxygen and the outer channel for feeding the as protection medium serving pyrolysis gas. Through this Arrangement becomes a local overheating of the iron bathing in the place where the oxygen enters avoided. The second nozzle can be single-tube and serves to supply the serving as carrier gas Pyrolysis gas with the materials to be processed.

The melt becomes horizon through the console in the iron bath Valley divided into two: below in the smaller reaction space with strong swirls and flushes of the liquid Pig iron, which is also due to the position of the nozzles, as well their number is strongly determined, and the upper one Calming room, which strongly dust formation limits. By this arrangement of the melting vessel, so like the nozzles, the entire gasification process is posi tiv influenced.

In the upper part of the iron bath reactor are one or several fume cupboards for exiting from the iron bath reactor raw gases attached. These raw gas deductions are available with supply lines for superheated steam in connection dung. About these steam supply lines Steam is introduced into the raw gases so that it with the raw gases, d. H. with the CO content of the raw gases converted in whole or in part, causing the hydrogen portion of the raw gases can be increased so that Syn thesegas is created.  

The synthesis gas is then passed through a waste heat boiler performed a gas purification and can be consumed leads. The energy gained in the waste heat boiler serves u. a. to operate a turbine with a Generator and an air separation plant. With this Air separation plant will be used to operate the iron bath required oxygen obtained. The stick fabric can be given to consumers.  

An example of the procedure and the device tion is explained with the help of the drawings:

Fig. 1 is a schematic flow diagram of an embodiment of the method according to the invention,

Fig. 2 iron bath in vertical section,

Fig. 3 u. 4 different versions of the iron bath reactor in horizontal section.

As shown in FIG. 1, the gasification unit consists of a combination of a fluidized bed pyrolysis reactor 10 and an iron bath reactor 71 . Via line 57 and entry 37 , hot product gas (return gas), which was pre-cleaned in cyclone 79 , is pressed into the fluidized bed pyrolysis via the grate 14 as a fluidizing medium and heat transfer medium. O ₂ or CO ₂ can also be entered as regulators via line 59 . Via line 23 , pretreated waste of 0 to 9 mm grain size is introduced into the fluidized-bed pyrolysis in a manner known per se. As a buffer and improver, dry, fine-grained lignite or hard coal is mixed in via line 24 , calcium carbonate or dolomite being simultaneously introduced via line 42 as acid binder.

In the fluidized bed 12 and pyrolysis room 11 chemical reactions take place, which are triggered by the sensible heat of the Rückga se. Gasify volatile substances, bound oxygen reacts with carbon, existing or bound water is split, pyrolysis gas, pyrolysis fine coke and pyrolysis coke are formed. In this hot atmosphere, waste of toxic or highly toxic nature in liquid, gaseous or pasty or solid form with a grain size of up to approx. 9 mm or sewage sludge or dredging sludge, also with mineral oil waste, which is preferably heated, can be fed via line 40 . Instead of coal, the biomass entry meter 38 can be used to enter the biomass that has been pretreated, possibly with CO ₂ via line 58, into the fluidized bed.

The pyrolysis gas, which also carries out the pyrolysis fine coke, which is mainly formed by the light fraction of the waste or the biomass or coal, is discharged via the outlet 41 and passed via line 51 to a mill 54 . A small gas stream 53 is split off in front of the mill 54 and is fed directly to the iron bath reactor 71 . The larger partial flow 52 , which is now used as carrier gas, takes over from the mill 54 the pyrolysis coke crushed to 0-3 mm, which was conveyed to the mill 54 via grate 14 , pyrolysis coke room 13 , discharge 36 and line 55 .

On the way to the iron bath reactor 71 high-temperature coke can be metered in via metering device 61 and chamber 60 as the first heater and via chamber 62 as possible second heater aluminum and / or silicon and / or optionally phosphorus.

From the iron bath reactor 71 , the product gas is fed via line 95 to line 80 , in which a cyclone 96 is interposed. Superheated steam is added via line 85 , where a catalyst-free conversion or partial conversion sets in quickly and the synthesis gas is fed from a heating boiler 69 , a gas purification 70 and via line 97 to consumption.

The steam generated in the waste heat boiler 69 is used in the turbine 67 to drive a generator 68 and an air separation plant 66 . While the generated nitrogen 98 is supplied to a third party, the oxygen goes via line 63 to the iron bath reactor 71 . On the line 63 dosing 61 are attached, the chamber 64 a flux z. B. introduce lime or dolomite and meter in via chamber 65 toxic or highly toxic, inert dusts for their elimination in the molten iron.

The iron bath reactor 71 may consist of a round melting vessel, as shown in Fig. 3 Darge, but should preferably be made in a trough-like form ( Fig. 4). The reactor is richly bricked 99 in the lower area, in the upper area the side wall is formed in a known manner by water coolers 73 , the interior of the furnace is protected by refractory material 76 . Underneath the melting mirror 74 , a console 75 sloping slightly forward is designed around the melting bed, which is pierced by at least one pair of nozzles 81 and 82 from the outer wall and whose mouths are flush with the vertical wall of the console and 100-400 mm, preferably 200 mm, flow into the melting bed 83 above the bottom of the bath. The Dü sen are at an angle of 90 ° to each other, so that the intersection point 9 of the angle 100-400 mm, preferably 200 mm, is in the melting bed 83 . One nozzle 82 is a two-tube nozzle, the inner channel for oxygen and connected to the line 63 , while the outer channel for a protective medium, namely pyrolysis gas, is connected to line 53 . The loaded carrier gas 52 (pyrolysis gas) is introduced into the iron bath reactor 71 via the nozzle 81 , which is a single-tube nozzle. In order to avoid a continuous renewal, and thus a contamination of the melt, drying over Chargieröff 72 continuously to 5-mark piece size shredded, reclaimed scrap melt were added and ei NEN tapping channel 84 and tap hole 77 intermittently withdrawn batch of pig iron, while the slag is continuously withdrawn via the slag hole 35 .

Claims (11)

1. Process for the gasification of carbon-containing wastes which are largely freed from inorganic materials and which are subjected to a pyrolysis treatment at temperatures of 400-1100 ° C. with hot product gas recirculated from the gasification process, then comminuted and together with additional fuels (heat generators) and during the pyrolysis treatment gases are gasified with the addition of oxygen, characterized in that

• - the pyrolysis of the waste crushed to less than 9 mm takes place in a fluidized bed together with additional fuel,
• - O ₂ and / or CO _{2 is introduced} for temperature control,
• - acid-binding agents (lime, dolomite) are added to the fluidized bed,
• - the pyrolysis coke is reduced to less than 3 mm,
• the pyrolysis coke is added to an iron melt bath reactor together with oxygen with the addition of known heat toners (high-temperature coke, Al, Si, P) and with most of the pyrolysis gas,
• - the remaining pyrolysis gas is loaded with an acid-binding agent (lime, dolomite) with a grain size of 0-3 mm and is fed separately into the iron bath reactor,
• that the iron bath reactor is continuously added to scrap shredded under 30 mm and, accordingly, the melt is drawn off discontinuously,
• - That toxic substances are used in the pyrolysis treatment and / or in gasification.

2. The method according to claim 1, characterized in that the Feed materials for the pyrolysis layer pre-dried the. 3. The method according to claim 1, characterized in that the Pyrolysis in the fluidized bed at a pressure of 1 to 20, preferably 3 to 8 bar. 4. The method according to claim 1 or one of the following, since characterized in that the toxic or highly toxic substances in liquid, gaseous or pasty or in solid form with a grain size of less than 9 mm the vertebrae layer are fed. 5. The method according to claim 1 or one of the following, since characterized in that the toxic or highly toxic substances in the form of liquid to pasty sludges mixed with petroleum products or waste into which Fluidized bed are injected. 6. The method according to claim 1 or one of the following, since characterized in that toxic or highly toxic Substances that cannot be processed in the fluidized bed  are, like contaminated earths, dried on a grain size of approx. 0-3 mm and the first partial stream be added from the pyrolysis. 7. The method according to claim 1, characterized in that the remaining partial stream of the pyrolysis gases before being introduced into toxic dusts are added to the iron bath reactor. 8. The method according to claim 1 or one of the following, since characterized in that the toxic or highly toxic substances containing dioxins or furans or dusts are. 9. The method according to claim 1 or one of the following, thereby ge indicates that the main product gas stream in known Way is hot-converted. 10. Apparatus for carrying out the method according to claim 1 or one of the following, with an iron bath generator with fuel and gasification feed lines below half the bath surface, characterized in that the sem a known fluidized bed pyrolysis reactor ( 10 ) with line ( 24 ) for additional fuel, outlet ( 41 ) for the dust-laden pyrolysis gas, discharge ( 36 ) for pyro lysekoks is connected upstream, its gas line ( 51 ) being connected to the iron bath generator ( 71 ) as delivery lines for its pyrolysis products, while it is un th with a return line ( 57 ) for product gas returned from the iron bath reactor ( 71 ) is connected and the melt pool vessel below the melt level ( 74 ) is exhibited all around with a refractory material ( 76 ) forming a slightly sloping console ( 75 ), through which at least one pair of nozzles ( 81 and 82 ), which with their mouths with the vertical wall of the Konso Complete le ( 75 ) and the nozzles are each at such an angle that their axis intersection ( 9 ) 100-400 mm, preferably 200 mm in the melt pool ( 83 ), with a nozzle ( 82 ) having two tubes, the inner channel of which Oxygen supply and its outer channel is connected to the pyrolysis gas supply, while the second nozzle ( 81 ) is single-pipe and connected to the supply of the carrier gas loaded with pyrolysis coke. 11. The device according to claim 10, characterized in that the mouths of the two nozzles ( 81 and 82 ) 100-400 mm, before preferably 200 mm, open out over the bottom of the bath.