DE4123406A1 - METHOD FOR GASIFYING LOW-QUALITY SOLID FUELS IN A SHAFT-SHAPED GASIFICATION REACTOR - Google Patents

Description

The invention relates to a method for gasifying inferior solid fuels according to the preamble of Claim 1.

Inferior fuels such as wet Lignite or hard coal with a high tar content, old tires etc. can also be deducted without unwanted emissions Product gas is gasified; in particular, the product gas free or nearly free of the calorific value and the further use restricting as well as the environment contaminants. For this purpose is a shaft-shaped gasification reactor according to the preamble of Claim 1 has been developed in which the special feature is that the bulk bed in the primary gas chamber is built up in two layers. A first layer of the bulk Gutbettes consists of a relatively high quality coke. The second layer of the bulk bed is stored as a relatively thin layer Layer on the first bulk layer and is from the inferior fuel formed. The second is Bulk material layer with its free bed area to the Pri Märgasbrenner facing in the primary gas chamber. The primary gas burner is made with a fuel, oxygen or air and possibly water vapor and supplies the for endothermic gasification process required sensible heat. As a fuel, the primary gas burner z. B. waste oils like this fed like a pasty residue from a paper mill. The primary gas generated by the combustion in the burner  occurs at a temperature of 1500 to 1800 ° C. At con clocks with the batch to be gasified (inferior Fuel, e.g. B. a mixture of used tires and deinking sludge) the primary gas reacts with this charge Raw gas. The raw gas shows when entering the second bulk good bed z. B. 1,864 ° C and then flows through it second bulk bed of coke and leaves it as ferti product gas at the top of the shaft gasifier. Of the Thickness of the (second) bulk bed, i.e. H. to gasify the the cargo (inferior fuel) and the Setting the primary gasification depends on whether that is behind the second bed of bulk material, e.g. B. the higher quality coke, also gasified or only or in primarily as a filter for the raw gas passing through serves. The primary gasification is either set on the ratio of oxygen to carbon carrier in the fuel ner, or over the total amount of primary gasifying substances or - if instead of air, pure oxygen via the burner is introduced - via the ratio of oxygen to water steam (EP 01 94 252 B1).

Have experiments with the aforementioned shaft carburetor now shown that in the high temperature gasification of a number low-quality fuels, especially shredder light Fraction from the motor vehicle recycling considerable problems me occur; in particular it is in some cases and ins especially with the shredder light fraction from the motor vehicle recycling difficult to load this charge so evenly into the Gasification zone, d. H. specifically in the primary gas space bring that the product gas a sufficiently uniform Quality. So far, there are no solutions to this problem published efforts have been made to the minor to briquette valuable fuel, and then put it in one  lumpy shape through conventional lock systems To abandon the shaft carburetor. The briquetting as such he turned out to be very complex and not yet mature enough.

Another previously unpublished lion approach did not lead to success. According to this Lö approach, the inferior fuel is ground, such as it z. B. for the use of fuels in entrained flow gasification reactor is known. This grinding turns out insofar as problematic, as wear-intensive materials, like glass, stones, iron and others in the inferior Fuel can be included. In addition, this is featured Very expensive.

Proceeding from this, the object of the invention reasons, inferior in gasification and / or difficult fuels to be handled, especially in gasification the shredder light fraction in motor vehicle recycling to ensure the most uniform possible product gas quality Afford.

To solve this problem, the procedure with the Features of claim 1 proposed.

The invention provides a number of significant advantages parts reached. These include a.

• - In the thermal pre-treatment step of inferior The gas fraction and the solid fraction fall towards fuel tion, especially if the inferior value fuel is a light shredder fraction, in a quantity ratio of combustible or gasifiable mate rial on how to operate a high temperature gasification  reactor of the type specified in claim 1 required (about 60% gas fraction and about 40% solid fraction tion) adding other fuels in the primary gas burner ner is therefore hardly necessary;
• - The solid fraction from the thermal pretreatment has egg properties such as smelting coke; therefore can on Use of cottage coke can be dispensed with entirely, so that Secondary fraction in the gasification reactor (solid charge) only from the solid fraction of the thermally treated low-quality solid fuel; the shaft carburetor no longer needs two different ones Cargo and can therefore be constructed more simply, such as in DE 29 20 922 C3 or in EP 01 43 106 B1 described;
• - Inferior combustion in the gasification according to the invention Environmental toxins such as dioxins and nitrogen oxides do not fall because the dioxins in the sub-stoichiometric Conditions performed gasification do not exist can and if they are in the fuel of the primary gas burner are present at the high combustion temperatures be destroyed; Nitrogen oxides from primary gas combustion are reduced under the gasification conditions; Furthermore metal oxides, for example, have one in comparison other recovery methods of inferior fuels lower degree of oxidation and are therefore less toxic;
• - fiber contained in the low-quality fuel, such as B. metals can be after the thermal pretreatment step from the solid fraction by a conventional Separation step to be separated before the solid fraction the gasification reactor is abandoned as a charge;
• - the entry of the solid cargo in the gasification reactor is significantly simplified.

While the process according to the invention reduces the gasification valuable fuels in a shaft carburetor which in the patent Claim 1 mentioned type without major handling problems with Batching the solid fraction in a way that allows ensures a relatively uniform product gas quality, then carry out the method steps according to claim to advantageous results if instead of the shaft mining a known entrained flow gasifier is used, provided that from the thermal pretreatment of the minor solid fuel to the for the Shredded entrained-flow gasifier compatible grain size range is noted. In this alternative solution are essentially achieved the same or corresponding advantages, as described above.

With regard to those to be fed to the primary gas burner Gas fraction from the thermal pretreatment of the inferior term fuel, it is understood that these are also solid Components in the form of fine-grained, especially dust-like can have gene material.

Thermal pretreatment with the addition of heat and essentially avoiding burning of Ingredients of the fuel separated into a gas and a solid fraction can be used in many different ways consequences. So-called pyrolysis plants are general for this known; because of the knowledge of their structure and their ver driving conditions do not need them here in detail to be explained in more detail. Typical examples of inventions Pyrolysis plants which can be used in accordance with the invention and other minors valuable fuels are e.g. B. the pyrolysis of waste wood in a fluidized bed reactor or the pyrolysis of chemical Production residues in the rotary tube reactor.  

The aforementioned and the claimed and in the The following embodiment described, fiction according to the components or process steps to be used lie in their size, shape, material selection and technical conception and its process conditions no special exceptions, so that in each known application criteria disagree can find limited application.

Further details, features and advantages of the Ge object of the invention result from the following Description of the associated drawing, using the - at playful - a preferred embodiment of the invention The procedure is explained.

The shaft carburetor 100 reproduced in detail in the basic flow diagram is known from DE 29 20 922 C3. A pressure vessel 1 , which has an outer insulation 33 , bil det the shaft carburetor 100th The pressure vessel 1 has a vertical upper section and a laterally angled lower section. In the upper section of the Druckbehäl age 1 , the solid charge is given via a lock 4 , which after each cycle with an inert gas, for. B. steam is flushed through a line 5 . The lumpy, solid charge arrives in a basket 3 taken from the cooling water pipes in the pressure vessel 1 and forms a bed 11 with an upper free surface 12 having a cone. The lines of the basket 3 are supplied via a lower ring distributor 31 , to which down pipes 30 , which are located in the space between the basket 3 and the pressure vessel 1 , lead from an upper ring distributor 29 , ah to which a cooling water supply line 7 is connected.

The basket 3 has an inward white projection 20 in the lower third, which forms the upper limit of an underlying primary gas chamber 21 . Due to the narrowing (passage) present in the basket 3, there is inevitably at the lower end of the bed 11 an inclined embankment-like free bed surface 13 which delimits the primary gas chamber 21 on this side.

At the bottom, the bed 11 stands on a slag pan 22 also formed by coolant lines on the lower part of the basket 3 . In the lower region, ie below the projection 20 , the inside of the basket 3 is finally provided with a slag pan 20 with a refractory ramming compound 32 . The lower free bed area 13 of the bed 11 forming embankment has a stand from an overflow weir 16 formed on the corner of the slag tray 22 facing away from the bed 11 .

Between the lower free surface of bed 13 and the overflow weir 16 of the Schachtverga sers 100 can be the liquid slag having a free surface in an image captured by the slag pan slag 22 collect bath 14 during operation. The outer part of the primary gas chamber 21 is delimited by the refractory mass 32 of the basket 3 .

The overflow weir 16 directly opposite a primary gas burner 2 is arranged in the wall of the pressure vessel 1 , to which the gas fraction from the thermal pre-treatment of the inferior fuel, oxygen or oxygen-containing gas and possibly steam are supplied. The primary gas jet 15 formed by the primary gas burner 2 is directed obliquely downward in the direction of the lower free fill surface 13 and the free surface of the slag bath 14 . In this way, intensive gasification is achieved on the lower free bed surface 13 and also the carbon-containing constituents floating on the slag bath 14 and clogging of the overflow weir 16 is prevented, because the primary gas jet 15 counteracts the slag flow flowing to the overflow weir 16 .

For the rest of the details, reference is made to DE 29 20 922 C3. The arrangement (shaft carburetor) for two charging goods which can also be used according to the invention as one of the possible alternatives is described in detail in EP 01 94 252 B1. On these two publications, full reference is made to content, it being noted that in DE 29 20 922 C3 the bed 11 consists of a relatively high-quality fuel, while the shaft gasifier described there in the case of the present invention for the solid fraction of the thermal treated inferior fuel is used.

As the basic flow diagram shows, the as "Waste" initially referred to inferior fuel plant called "pyrolysis" for thermal preparation action taken. This is done with the addition of heat and essentially avoiding the burning of Be components of the input material (low-quality fuel fes) the procedure being carried out in a manner known per se so that a gas and a solid reaction ent stand that are separated from each other and in the reason flow diagram on the one hand as "pyrolysis gas" (gas fraction) and on the other hand as "pyrolysis coke and recyclables" (Festfrak tion) are designated. It is understood that a any liquid fraction that forms part of the "Festfrak tion "and / or" gas fraction ". With this thermi  pretreatment z. B. the following procedural conditions conditions set: Temperatures approx. 40-550 ° C and a degassing pressure of approx. 1-10 m bar.

In a separator, such as an air classifier, a sieve or other, the "solid fraction" can be separated into its components "pyrolysis coke" and "recyclables". The "pyrolysis coke" is then abandoned via the lock 4 to the shaft carburetor 100 .

The resulting in the thermal pretreatment "pyrolysis gas" (gas fraction) is given to the primary gas burner 2 .

While the slag accumulating in the shaft gasifier 100 is discharged at the discharge lock 26 , the product gas falls on the gas outlet 6 after flowing through the bed 11 and from there is further cleaned of gas and solid impurities (H ₂ S, HCL, dust). a CHP unit designated as a gaseous fuel for machines such. B. gas engines or gas turbines be used, which takes place in the combined heat and power plant combustion of the product gas, a flue gas, which is usually released into the atmosphere via a fireplace. The pyrolysis drum can be heated either directly by burning pyrolysis gas or indirectly by removing flue gas from the CHP.

Reference list

1 pressure vessel
2 primary gas burners
3 basket
4 lock
5 inert gas purge line
6 gas outlet
7 Cooling water supply line
8 cooling water discharge line
9 screw conveyor
10 screw conveyor
11 fill
12 surface
13 fill area
14 slag bath
15 primary gas jet
16 overflow weir
17 slag stream
18 pressurized water jet
19 water bath
20 head start
21 primary gas chamber
22 slag pan
23 water jet lance
24 steam passage opening
25 steam outlet
26 discharge lock
27 condensate drain
28 ring collectors
29 ring distributor
30 downpipes
31 ring distributor
32 refractory mass
33 External insulation
100 shaft carburettors

Claims (2)

1. Process for gasifying low-quality solid fuels with oxygen or oxygen-containing gases and water vapor using a shaft-shaped container (shaft gasifier) for receiving a solid charge good (low-quality fuel) with the formation of a traveling layer with a passage for the cargo at the lower end of the container and a connected to the passage, arranged under the container, fired by a primary gas burner primary gas chamber in the above a support surface facing the primary gas burner bed surface of a solid charge well formed below the passage is formed, in which the product gas and Slag can be removed from the gasification process in a suitable manner, characterized in that

• a) the low-quality fuel is first separated into a gas and a solid fraction by thermal pretreatment with the addition of heat and essentially avoiding the burning of constituents of the fuel,
• b) the solid fraction as the solid charge to be gasified is given up well in the traveling layer of the shaft gasifier and
• c) the gas fraction is fed to the primary gas burner as the (endothermic) gasification process for introducing the heat of the gas to be supplied with formation of an entrained flow in the primary gas chamber.

2. The method according to claim 1, characterized in that the product gas as a gaseous fuel for operation a power plant, especially a cogeneration unit kes, is used.