WO1993002162A1

WO1993002162A1 - Process for producing synthetic or fuel gasses from solid or pasty residues and waste or low-grade fuels in a gasifying reactor

Info

Publication number: WO1993002162A1
Application number: PCT/EP1992/001607
Authority: WO
Inventors: Karl-Heinz Redepenning; H. Peter Wenning
Original assignee: John Brown Deutsche Engineering Gmbh; Veba Oel Technologie Gmbh
Priority date: 1991-07-15
Filing date: 1992-07-15
Publication date: 1993-02-04
Also published as: CA2113636A1; EP0600923A1; FI940184A0; DE59207017D1; DE4123406A1; EP0600923B1; FI940184A; JPH07502766A; FI106314B; AU2344492A; JP3203580B2; EP0523815A1; DE4123406C2

Abstract

A process is disclosed for producing synthetic and/or fuel gasses from organic elements-containing residues and waste and/or low-grade fuels (charging materials) with oxygen-containing gasses by means of a flying stream or shaft gasifyier. In order to obtain a product gas of a quality as uniform as possible, in spite of the handling difficulties presented by the charging materials, that may in particular be shredder-produced light materials from car recycling, a pyrolytic stage is arranged upstream of the gasifying reactor. The solid materials that leave the pyrolytic stage are gasified into product gas in the gasifying reactor and the gaseous fraction leaving the pyrolytic stage is used to supply heat to the production process and/or for further producing product gas.

Description

Process for producing synthesis or fuel gases from solid or pasty residues and waste materials or inferior fuels in a gasification reactor

The invention relates to a method according to the preamble of claim 1.

Since the deposition of solid or pasty residues and waste materials and low-quality fuels is no longer justifiable, the recycling of these materials is becoming increasingly important. These substances include e.g. B. shredder light goods from motor vehicles, plastics, oil, paint and solvent sludge, partially watered sewage sludge, wet brown or hard coal with a high tar content, used tires and many others. These substances have in common that they contain organic components.

Inferior fuels, such as wet brown coal or hard coal with a high tar content, old tires, etc. can already be gasified today - even without undesired emissions in the product gas withdrawn; in particular, the product gas can be free or almost free of impurities which reduce the calorific value and restrict further use and pollute the environment. A shaft-shaped gasification reactor has been developed for this purpose, in which the special feature is that the bulk material bed in the primary gas chamber is constructed in two layers. A first layer of rubble Gutbettes consists of a relatively high quality coke. The second layer of the bulk bed is stored as a relatively thin layer on the first bulk layer and is formed by the inferior fuel. The free bulk surface of the second bulk material layer faces the primary gas burner in the primary gas chamber. A fuel, oxygen or air and possibly water vapor are applied to the primary gas burner and supplies the sensible heat required for the endothermic gasification process. As the primary gas burner z. B. waste oils and 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. When in contact with the batch to be gasified (low-quality fuel, eg a mixture of used tires and deinking sludge), the primary gas reacts with this batch to raw gas. The raw gas has z. B. 1,864 ° C and then flows through the second bulk bed of coke and leaves this as finished product gas at the upper end of the shaft gasifier. It depends on the thickness of the (second) bed of bulk goods, ie the charge to be gasified (inferior fuel) and on the setting of the primary gasification, whether the charge lying behind the second bed of bulk goods, e.g. B. the higher quality coke, also gasified or used only or primarily as a filter for the raw gas passing through. The setting of the Primärvergasuπg either the ratio of oxygen to carbon carrier in Bren¬ ner, or the total amount of Primärvergasungsstoffeπ or - if introduced instead of air, pure oxygen through the ^burners' is - vapor on the ratio of oxygen to Wasser¬ (EP 0194252 Bl).

Experiments with the above-mentioned shaft gasifier have now shown that a number of high-temperature gasification of feed materials, such as. B. the shredder light fraction from motor vehicle recycling considerable problems occur; in particular, it is difficult in some cases, and in particular in the case of the shredder light fraction from vehicle recycling, to introduce this charging material so uniformly into the gasification zone, ie specifically into the primary gas space, that the product gas has a sufficiently uniform quality. To solve this problem, previously unpublished efforts have been made to briquette the inferior fuel in order to then give it to the shaft gasifier in a lumpy form by means of conventional lock systems. The briquetting as such, however, proved to be very complex and not yet mature enough.

Another hitherto unpublished approach has also not led to success. According to this approach, the starting material is ground, as it is for. B. is known for the use of fuels in an entrained-flow gasification reactor. This grinding proves to be problematic insofar as wear-intensive substances such as glass, stones, iron and others can be contained in the inferior fuel. In addition, this procedure is very cost-intensive.

Proceeding from this, the invention is based on the object, in the gasification of inferior and / or difficult to handle starting materials and / or residues and waste materials containing organic constituents, in particular in the gasification of the shredder light fraction during motor vehicle utilization, a product gas quality which is as uniform as possible to ensure activity.

To achieve this object, the method with the features of claim 1 is proposed. A number of significant advantages are achieved by the invention. These include:

In the thermal pretreatment step (pyrolysis treatment step) of the feedstock, the gas fraction and the solid fraction, in particular when the feedstock is a light shredder fraction, are obtained in a quantity ratio of combustible or gasifiable material as is the case for operation a shaft gasifier or entrained flow gasification reactor is required (about 60% gas fraction and about 40% solid fraction); it is practically not necessary to add other fuels in a primary gas burner;

- The solid fraction from the thermal pretreatment has properties such as a smelted coke; therefore in the gasification on the use of z. B. cottage coke can be dispensed with entirely, so that the secondary fraction in the gasification reactor (solid charge) only consists of the solid fraction of the thermally treated inferior feedstock; if a shaft gasifier is used, it no longer requires two different charging goods and can therefore be of simpler construction, as described, for example, in DE 29 20 922 C3 or in EP 0 143 106 B1;

- In the gasification of the feedstocks according to the invention, environmental toxins such as dioxins and nitrogen oxides do not occur, since the dioxins cannot exist in the gasification carried out under substoichiometric conditions and, if they are present in the fuel of the primary gas burner, decompose at the relatively high combustion temperatures ¬ be disturbed; Nitrogen oxides from the primary gas expansion are reduced under the gasification conditions; in addition, metal oxides that occur have a lower degree of oxidation than other recycling methods and are therefore less toxic; - Fiber contained in the feed, such as. B. After the thermal pretreatment step, metals can be separated from the solid fraction by a conventional separation step before the solid fraction is fed to the gasification reactor as a charge;

- The entry of the solid charge in the gasification reactor is significantly simplified and evened out.

Gasification reactors operating according to the preferred entrained flow principle (entrained flow gasifier) are sufficiently known and therefore do not require any special description at this point; reference is made, for example, to DE-C2 27 21 047 and EP-B1-0 011 151. While the use of a gasification reactor operating according to the entrained flow principle (also known as the airborne dust principle) is preferred according to the invention, there is alternatively also a gasification reactor operating according to the fluidized bed principle, as it u. a. is addressed in EP-B1-0 011 151, for use according to the invention. Whereas a so-called fluidized bed gasifier uses a relatively wide and coarse grain size range for the solid to be gasified in the gasifier (typical values are 0.1 mm to 100 mm), grain size ranges of about 0.001 mm to 5 mm are used for so-called entrained flow gasifiers . The particle size range of the solid fraction obtained behind the pyrolysis treatment stage according to the invention is adjusted after the pyrolysis treatment and before the entrained flow gasification by grinding, sieving and / or sifting, the particle size range being reduced (claim 2).

In contrast, when using a shaft gasifier, which is also preferred according to the invention, the solids obtained after the pyrolysis treatment stage can preferably be used can be used directly in the shaft gasifier without a special adjustment of the grain size range and without major handling problems when charging the solid fraction; A relatively uniform product gas quality is also ensured with this driving style. The shaft carburettors mentioned at the outset (EP-B1-0 194 252) are basically suitable for such an application. Such a shaft gasifier has a shaft-shaped container for receiving the solid cargo to be obtained behind the pyrolysis treatment stage, forming a traveling layer with a passage for the cargo at the lower end of the container. Connected to the passage is a primary gas chamber arranged under the container and fired by a primary gas burner, in which a bed surface facing the primary gas burner of a bulk material bed formed by the solid charge material below the passage is formed above a support surface, the pro ¬ duct gas and the slag are withdrawn from the gasification process in a suitable manner. In particular, when such a shaft gasifier is used according to the invention, it is advantageous to supply the fraction which is gaseous behind the pyrolysis treatment stage and which is gaseous under operating conditions of the pyrolysis treatment to the total primary gas burner, in order in this way to supply the endothermic gasification process with gasification heat. In this case, the gas fraction and, if appropriate, further fuels are preferably supplied with the formation of an entrained flow in the primary gas chamber.

However, the gas fraction obtained after the pyrolysis treatment stage is preferably first subjected to a condensation step. The gas fraction obtained after the condensation stage is then further used in the synthetic and / or fuel gas production process according to the invention. For this purpose, this gas fraction ^'the Vergasungsreak- Tor or the pyrolysis treatment stage for introducing heat for the endothermic pyrolysis or gasification step, or admixed to the product gas obtained behind the gasification reactor as part of the combustion or synthesis gas.

The liquid fraction obtained after the condensation stage can possibly be used in another process, but is preferably fed to the gasification reactor for gasification and / or for the introduction of heat for the endothermic gasification process. Here, according to a preferred embodiment of the invention (claim 3), the solid fraction obtained after the pyrolysis treatment stage and the liquid fraction obtained after the condensation stage are mixed and fed to the gasification reactor together, depending on the consistency of the mixture, preferably a pump or a screw machine being used. Suitable conveying bodies and procedures for this purpose are known from DE-C2-27 21 047 and EP-B1-0 011 151 as examples.

A particularly advantageous use of the gases produced according to the invention results from claim 4.

It is also possible to add inorganic residues or waste materials to the feedstock in order to remove contaminating substances contained therein from the residue or waste material in the pyrolysis treatment stage or in the gasification stage (claim 5).

Further method variants within the scope of the invention result in connection with the block diagram to be explained (FIG. 1). While feedstocks to be processed according to the invention are either essentially solid or pasty, pasty not only contains solid / liquid mixtures, but also more or less thickened. As liquids are to be understood, liquid feedstocks, ie residues and waste materials and / or inferior fuels containing organic constituents, can in principle also be used or used for the production process of synthetic and / or fuel gases according to the invention. As a rule, however, liquid feedstocks of the aforementioned type can also be converted to synthesis and / or fuel gases in other processes.

With regard to the type of gasification reactor used, in addition to those which, as is preferred, work according to the entrained flow principle or are designed as shaft gasifiers, other types of gasifiers can also be used according to the invention. An example of this are the fluidized bed gasifiers already mentioned.

In the production process according to the invention, the gasification is generally carried out under a pressure of preferably 10 to 100 bar. Basically, higher gasification pressures are possible. The gasification can also be carried out at atmospheric pressure or in a slight negative pressure (if suction draft fans are used).

The invention is therefore based on the basic idea of producing synthetic and / or fuel gases from residues and waste materials containing organic constituents and / or inferior fuels (feedstock) with oxygen or oxygen-old gases and possibly water vapor, the feedstock first by thermal pretreatment with supply of heat and essentially avoiding combustion of constituents of the starting material (pyrolyzation treatment) into a gaseous and a solid fraction under operating conditions, the solid fraction to produce the synthesis and / or fuel gas in the To gasify the gasification reactor and to process the gas fraction at least partially in the manufacturing process for introducing process heat and / or for producing additional amounts of synthesis gas and / or fuel gas.

With regard to the gas or liquid fraction to be fed to the gasification reactor from the thermal pretreatment of the starting material, it goes without saying that these can also have solid constituents in the form of fine-grained, in particular dust-like material.

The thermal pretreatment with the addition of heat and essentially avoiding the burning of constituents of the fuel with separation into a gas and a solid fraction can be carried out in a variety of ways. So-called pyrolysis plants are generally known for this; Because of their knowledge of their structure and their procedural conditions, these need not be explained in detail here. Typical examples of pyrolysis plants which can be used according to the invention and other inferior fuels are e.g. B. the pyrolysis of waste wood in the fluidized bed reactor or the pyrolysis of chemical production residues in the rotary tube reactor.

The size, shape, material selection, technical conception and process conditions of the above-mentioned components as well as the components and process steps to be used according to the invention and to be used according to the invention are not subject to any special exceptions, so that the respective ones Known application criteria can be used without restriction. Further details, features and advantages of the subject matter of the invention result from the following description of the associated drawing. The drawing shows:

Fig. 1 is a block diagram as well

2 shows a simplified process sketch for the application of a shaft gasifier.

The block diagram shown in FIG. 1 applies in principle to every type of gasification reactor, but is explained below primarily in connection with the preferred use of an entrained flow gasification reactor. Alternative procedures are shown in dashed lines. Process stages π that are preferably used are additionally outlined with a dashed line.

1, an organic constituent containing residual or waste material and / or inferior fuel, hereinafter referred to as feedstock, is subjected to a pyrolysis treatment stage 101, such as e.g. an indirectly heated rotary kiln (drum wall temperature up to 900 ° C). In this, the feed is pretreated, largely free of oxygen, with the addition of heat and essentially avoiding the burning of constituents of the feed at temperatures between approx. 300 and 650 ° C. For the supply of heat, extraneous gas, behind the gasification reactor 102 product gas and / or the condensation stage 103 downstream of a pyrolysis stage, preferably in a pyrolysis gas purification stage 104, can be used.

The intermediate product obtained from the feed material in the pyrolysis treatment stage 101 is separated as steam (Gas fraction) and coke (solid fraction) removed. The solid fraction is adjusted, if necessary after setting the grain size range in a grinding, sieving and / or sifting stage 105, to the level which is compatible with the respective gasification reactor type (gasification reactor 102) and fed to the gasification reactor 102, for example pneumatically. Recyclables contained in the solid fraction, e.g. B. metals can in a separation stage 106, z. B. a screening device, are removed before the solid fraction is fed to the gasification reactor 102.

The gas fraction obtained behind the pyrolysis treatment stage 101 is either fed as vapor to the gasification reactor for the gasification and / or introduction of heat of reaction or is first passed through a condensation stage 103. The residual gas deposited therein under the condensation conditions is either fed, preferably after passing through a pyrolysis gas purification stage 104, to the pyrolysis treatment stage for introducing process heat. As an alternative or in addition, the pyrolysis gas can be fed to the gasification reactor 102 or the product gas stream behind it to introduce gasification heat. In these cases, a pyrolysis gas purification stage may be omitted.

The oil (liquid fraction) obtained behind the condensation stage 103 is recycled in other processes or, as is preferred, introduced into the gasification reactor 102. Especially when this oil is to be gasified together with the solid fraction from the pyrolytic treatment stage 101, the two fractions can first be combined and fed to the gasification reactor 102 by means of a pump or screw machine 107.

After the gasification reactor, there are inorganic constituents which no longer have to be deposited, but which can be used as valuable materials. The product gas obtained behind the gasification reactor 102 will generally be cleaned in a gas cleaning stage 108. The constituents removed from the product gas can be fed to the gasification reactor 102 at least as a partial stream, so that they are divided there into product gas or inorganic constituents. In addition, enriched harmful gas components such as sulfur, salts and heavy metals can be used further.

The product gas accumulating behind the gas purification stage 108 can, as is preferred, be fired in a power plant 109, possibly already existing, or, if necessary partially, in the pyrolysis treatment stage 101 or used as synthesis gas or other fuel gas.

Schachtverga¬ ser 100 shown in detail in FIG. 2 is known from DE 29 20 922 C3. A pressure vessel 1, which has external insulation 33, forms the shaft carburetor 100. The pressure vessel 1 has a vertical upper section and a laterally angled lower section. In the upper section of the pressure vessel 1, the solid charge is placed on a lock 4, which after each cycle with an inert gas, for. B. steam is flushed through a line 5. The lumpy, solid cargo arrives in a basket 3 from cooling water pipes accommodated in the pressure vessel 1 and forms a bed 11 therein with a cone of material having an upper free surface 12. The lines of the basket 3 are supplied via a lower ring distributor 31, to which down pipes 30, which lie in the space between the basket 3 and the pressure vessel 1, lead from an upper ring distributor 29, to which a cooling water supply line 7 is connected. The basket 3 has in the lower third an inward projection 20 which forms the upper boundary of an underlying primary gas chamber 21. Because of the narrowing (passage) present in the basket 3, an inclined, embankment-like free fill surface 13, which delimits the primary gas chamber 21 on this side, inevitably arises at the lower end of the fill 11.

Below is the Schüttuπg 11 on a at the lower part of the basket 3 also formed by coolant lines slag pan 22. In the lower area, ie below the projection 20, the inside of the basket 3, including the slag tray 20, is provided with a refractory ramming compound 32. The slope forming the lower free fill surface 13 of the fill 11 is at a distance from an overflow weir 16 formed on the corner of the slag tray 22 facing away from the fill 11.

When the chess gasifier 100 is in operation, the liquid slag with a free surface can collect between the lower free bed surface 13 and the overflow weir 16 in a slag bath 14 taken up by the slag wall 22. The outer part of the primary gas chamber 21 is delimited by the refractory mass 32 of the basket 3.

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

For the other 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 0 194 252 B1. Full reference is made to these two printed publications, 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 thermally treated low-quality fuel is used.

As FIG. 2 shows, the

"Waste" is initially fed to a plant for thermal pretreatment called "Pyrolysis". This takes place with the supply of heat and substantially while avoiding the combustion of constituents of the starting material (low-quality fuel), the process being carried out in a manner known per se so that a gas and a solid tract are formed. which are separated from one another and are shown in FIG. 2 on the one hand as "pyrolysis gas" (gas fraction) and on the other hand as "pyrolysis coke and valuable materials" (solid fraction). It goes without saying that any liquid fraction which may occur can be a component of the "solid fraction" and / or "gas fraction". In this thermal pretreatment z. B. set the following process conditions: Temperatures approx. 300 - 650 ° C and a degassing pressure of approx. 0.9 X 10 ^{5 to} 1, 2 X 10 ⁵ Pascal.

The "solid fraction" can be separated into its components "pyrolysis coke" and "valuable materials" in a separating apparatus, such as an air classifier, a sieve or other. The "pyrolysis coke" is then fed to the shaft carburetor 100 via the lock 4.

The "pyrolysis gas" (gas fraction) obtained in the thermal pretreatment is fed 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 accumulates at the gas outlet 6 after flowing through the bed 11 and from there is after further cleaning of gas and solid impurities (H "S, HCL, Dust) a CHP unit designated as a gaseous fuel for machines such. B. gas engines or gas turbines be¬ used, the flue gas occurring in the combined heat and power unit combustion of the product gas, which is usually released into the atmosphere via a chimney. The pyrolysis drum can be heated either directly by increasing the cost of pyrolysis gas or indirectly by removing flue gas from the CHP.

Reference symbol list

1 pressure vessel 32 refractory mass primary gas burner 33 outer insulation basket lock 100 shaft gasifier inert gas flushing line 101 pyrolysis treatment stage gas outlet 102 gasification reactor cooling water supply line 103 condensation stage cooling water discharge stage auger 105 grinding, sieving and / or surface cleaning stage pumping auger 109 power plant primary gas jet overflow weir slag flow pressurized water jet water bath projection primary gas chamber slag tub water jet lance steam through opening steam outlet discharge lock condensate water outlet ring collector ring distributor downpipes downpipes ring distributor

Claims

Claims:

1. Process for the production of synthesis and / or fuel gases from solid or pasty, organic and organic residues and waste materials and / or inferior fuels (feedstocks) with oxygen or oxygen-containing gases and possibly water vapor using one that works according to the entrained flow principle or as a gasification reactor designed as a shaft gasifier at temperatures of about 800 ° C to about 1,700 ° C and possibly higher, characterized in that a) initially by a thermal pretreatment with supply of heat and essentially avoiding the burning of constituents the feedstock (pyrolysis treatment), in particular in a heated rotary tube, is separated into a gaseous, in particular vaporous, and a solid fraction under operating conditions, b) the solid fraction as a solid batch to be gasified, if appropriate after separation of valuable materials, the Gassing reactor is abandoned and c) the gasf Action is also given to the gasification reactor or, after a condensation step, is used in the manufacturing process in such a way that the gas fraction obtained behind the condensation stage is combined directly as part of the synthesis and / or fuel gas with the product gas stream occurring behind the gasification reactor or is supplied to the gasification reactor or the pyrolysis treatment stage for introducing heat for the endothermic process and the liquid fraction occurring behind the condensation stage is used in another process or the gasification reactor for gasification and / or for the introduction of heat for the endothermic gasification process is supplied.

2. The method according to claim 1, characterized in that the accumulating behind the pyrolysis treatment stage- nuπgs bandwidth of the solid fraction before gasification in an entrained-flow gasification reactor is reduced by grinding, sieving and / or sifting.

3. The method according to claim 1 or 2, characterized gekenn¬ characterized in that the after the pyrolysis treatment solid fraction and the liquid fraction accruing behind the condensation stage an¬ mixed and preferably fed together by means of a pump or screw machine, the gasification reactor.

4. The method according to any one of claims 1 to 3, characterized in that the product gas obtained behind the gasification reactor and possibly behind the condensation stage, possibly after removal of any existing pollutants (Schadgasbe¬ components) as a gaseous fuel for the operation of a, if necessary existing power plant, in particular a combined heat and power plant, is used.

5. The method according to any one of claims 1 to 4, characterized in that inorganic residues or waste materials are added to the feedstock.