DE1168005B - Method and device for incinerating solid waste - Google Patents

Description

Method and device for incinerating solid waste The invention relates to a method and a device for combustion and converting solid waste, especially rubbish, into chemically neutral ones Products of inorganic composition and suitable physical nature or those products which, with or without the use of foreign substances, e.g. B. Surcharges suitable type, are usable.

The hygienic disposal of waste from residential areas or of industrial plants is moving more and more into the foreground of public interest. In particular, the accommodation of the increasing garbage of the big cities become a difficult problem. Its discharge in dumps or pits, the vermin and attract rats as well as contaminate the groundwater and spread unpleasant smells, is only a makeshift solution that is unsustainable in the long run. Therefore one has already different places tries with more or less success to burn the waste matter. With good Burning out, the remaining ash is hygienically perfect and can be safely be used to fill pits and the like. But the garbage is a waste material its composition and content of combustible components within wide limits can fluctuate. These fluctuations, especially with regard to its moisture content, are both local and seasonal and place at a furnace high requirements, which in most cases cannot be met without special measures can be. As a result of the low combustion temperature, due to the low Calorific value and the high moisture content of the garbage as well as the large differences of the garbage from a chemical and physical point of view is the incineration residue sometimes not completely burned out and of a quality that makes it worthless power and causes high costs for its accommodation. For the same reason the exhaust gases from the furnace are foul-smelling.

There is also already sulphite waste liquor, a liquid waste from the Paper manufacture, burned in pulverized coal furnaces. The high water content of the Waste liquor, however, significantly lowered the furnace temperature, which resulted in the The combustion process of the coal dust deteriorated. It was therefore suggested that to carry out the incineration of the waste liquor separately from that of the coal dust. In an antechamber, which is arranged next to the pulverized coal furnace, is the through Nozzles atomized waste liquor burned with air. The combustion gases from the antechamber and from the pulverized coal combustion are brought together and shared by the steam boiler directed. As a result, the combustion process in the pulverized coal furnace is not affected disturbed.

It is much more difficult to completely remove solid waste such as garbage burn. The colorful jumbled fabrics of different sizes and properties, which are only partially combustible and can have a water content of up to 60% Combustion properties so different that even on grates special construction no complete burnout can be achieved. The ashes thrown from these grates is also inconsistent and worthless. Their removal requires a high level of technicality Expenditure.

For these reasons it is considered beneficial to be incombustible To convert residues of the waste materials into the molten state, whereby they become chemically neutral and of a uniform nature, and then to bring them into an easily transportable and usable form, e.g. B. by Granulating or pouring into molds. With the normally low calorific value and This can only be achieved with the help of additional high moisture content of the waste materials Burning of fuels, whereby the melting process is not caused by the high water vapor content Flue gases of the waste may be disturbed.

This is essentially achieved in that the combustion of the Waste and the melting of the slag takes place separately from one another and the flue gases generated during waste incineration only occur during incineration of the fuel formed flue gases are added if the latter the Have left the melting room. As mentioned before, you already have liquid waste similarly burned with success. These however do not have any incombustible residues and can be completely burned in an antechamber. In the case of solid, particularly inconsistent waste materials with incombustible components Further measures are necessary to dry them and as much as possible burn out as well as the incombustible residues preheated in the melting chamber to be introduced and melted there to form a homogeneous, liquid, peelable product. During the melting process, for example, not completely burned residues burn more organic Components in the waste residue are completely removed.

According to the method according to the invention in a known manner solid waste materials moved through a heating room and dried and first heated, then fed to a melting chamber in which their incombustible residues are melted by the introduction of fuels and from which the melted material is drained periodically or continuously, according to the invention by the Layer of waste materials moved essentially in the horizontal direction in the heating chamber Evenly distributed hot combustion gases in the direction of movement and, if necessary Combustion agent or with sufficient content of combustible components only Combustion agents are passed, also in a known manner perpendicular to the direction of movement can be introduced into the layer of waste materials, and the heated residues are fed to a melting chamber, preferably continuously, in a broad front, in which they are in a thin layer of the effect of the oncoming flow, through immediate combustion of fine-grained solid or liquid or gaseous fuels with combustion agents exposed combustion gases and the incombustible residues in the molten state as well as the exhaust gases from the heating and merged from the melting chamber after releasing their heat for heating and melting and withdrawn together in a known manner.

Air is generally used as the combustion medium. In the case of waste materials, which are melted down with or without surcharges to produce products of higher value can, whereby very high temperatures have to be achieved, it can be economical be portable, use oxygen or oxygen-enriched air as a means of combustion to use.

The merging of the moderately hot exhaust gases from the heating room and the very hot exhaust gases from the melting chamber cause the destruction of the The heating of the waste materials produces malodorous or chemically aggressive substances Gases and vapors by decomposing at the high mixing temperature. The tangible one Heat from the hot exhaust gases is used to preheat the combustion agent and / or preferably used to generate steam. But it can also be for someone else heat consuming process are used.

The airborne dust entrained in the exhaust gases is, according to the invention, in a Dedusting device of known design deposited and returned to the melting chamber. This return is preferably carried out using a dust pump of a known type Using a carrier gas, e.g. B. air or flue gas. According to the invention, the formed melt products from the waste materials and the ashes of the burned fuels (Slag) are collected in the bottom of the melting chamber, which is designed as a sump and form a slag bath, which in a known manner by the flow energy of the Fuels and combustion agents introduced into the melting chamber in a turbulent manner Movement is maintained, the slag being continuously or through an overflow is withdrawn periodically through a tap hole as new melt products appear form. As a result, the melt products remain in the melt space for a longer period of time constant intimate mixing. The melted residues of various waste materials Origin is therefore homogenized in the turbulent slag bath and as a mixed melt product peeled off of uniform consistency.

With suitable training and furnishing of the heating room according to the invention can waste materials without prior comminution and processing process even if bulky pieces are present. Unless the waste materials Contains iron and metal parts and these have not previously been separated and separated are recycled, they are melted down in the melting chamber after they have been preheated. Due to their higher specific weight, the liquid metal collects on the The bottom of the slag sump, from where it passes through a tap hole in the bottom or to the Sidewalls near the bottom of the slag sump periodically or continuously withdrawn will. In order to avoid metal losses through oxidation, the is put into the melting chamber imported fuel burned with lack of combustion agent. The ones from the smelting room withdrawing gases. which still contain flammable components are then introduced completely burned out by combustion agents above the melting chamber.

The waste materials contain little iron and metal parts, so that their recovery is not worthwhile, according to the invention, the one introduced into the melting space becomes Fuel burned with excess combustion agent to the melting metal parts to convert the waste materials into metal oxides and slag them.

If necessary, the melting point can be increased by suitable additives or the viscosity of the slag can be lowered. Depending on whether the melt products have basic or acidic character, are either acidic, e.g. B. sand or basic Substances, e.g. B. lime or other flux to the heating room or directly to the melting room fed. Even in those cases where the melt product has a special composition should achieve to make it useful for recycling z. B. supply as building material can. components of the composition are supplemented or enriched by supplements.

The method according to the invention is versatile. Allows, taking advantage of all economic conditions, organic waste materials and / or of an inorganic nature in hygienically usable products. In addition to the chemically neutral melt products, steam of any voltage and Temperature generated for heating purposes or for generation of electrical Electricity can be used. The procedure is of particular importance for the Incineration of municipal waste and certain waste products from the chemical industry, their removal and conversion into usable substances and steam or electrical Electricity without nuisance to the environment through malodorous or corrosive and dusty Exhaust gases is possible. The additional use of fuel means nothing Loss, as their heat of combustion is used to generate steam or for other purposes is exploited.

The device for performing the method according to the invention sees a heating room for receiving the waste materials and a melting room for The incombustible waste residue is melted down and consists of a conveyor system known design for the ongoing transport of waste materials through the heating room in the direction of the melting chamber and distribution channels in the heating chamber that connect with a furnace for solid, liquid or gaseous fuels and through the combustion gases of the furnace, possibly with an excess of combustion agents or through which only incineration agents are fed into the layer of waste materials, as well as through nozzles for the introduction of fuels and combustion agents into the melting chamber, which are preheated to the preferably continuously introduced Waste materials are directed.

The conveyor can simultaneously introduce and distribute the combustion agent, e.g. B. air, and serve as a traveling grate, moving grate, step grate or the like. Be formed.

The preheated waste materials are removed from the heating room through an opening introduced into the melting chamber. An opening in the bottom of the melting chamber is used for the outflow of the molten products.

Solid fuels are usually fine-grained or powdery State pneumatically with the help of a carrier gas, e.g. B. air or flue gas, promoted. Liquid fuels are dispensed with the aid of an atomizing agent, e.g. B. Air, before atomized their entry in a known manner.

According to the invention, the bottom of the melting space can be designed as a trough in which the liquid melt products collect. They form a slag pool the height of which is maintained by an overflow or tap hole. Another one A needle hole at the deepest point of the floor or near the floor can be provided for the extraction of liquid metals. Through nozzles in the exhaust gas outlet of the melting chamber or / and the heating space, combustion agents are introduced, if still unburned Extract gases from one or both rooms. For the introduction of surcharges are Nozzles are provided which open into the melting chamber and which the additives, preferably fine-grained or dusty, by means of a carrier gas such as air or flue gas, be fed pneumatically. The surcharges can also be paid by funding agencies are entered into the heating room and then arrive with the waste materials in the preheated state in the melting chamber.

On the exhaust gas side, the heating and melting chamber are heat exchangers for the preheating of the combustion agent, generation and superheating of steam or Like. Subordinate. A dedusting device is installed between or behind the heat exchangers intended for the exhaust gases. For the return of the separated fly ash in The melting chamber is used. Conveyor devices of known design and nozzles that are used in open into the melting chamber.

Heating room, melting room, connecting channels and shaft for the Discharge of the exhaust gases can be components of a steam boiler system, in their Double jacket or pipe system the water to be evaporated in natural circulation and / or Forced flow is heated.

A steam boiler system with liquid slag removal can be used for melting or destruction of waste materials according to the invention are used if your one Heating space for the waste materials is allocated, from which the heated waste materials constantly introduced into the melting furnace and the exhaust gases above the melting furnace into the radiation chamber of the boiler.

In the drawing, two exemplary embodiments of the subject matter are shown in FIG of the invention shown schematically.

F i g. 1 shows a plant for melting waste materials and F i G. 2 heating room and melting room, with the bottom of the melting room as a slag pan is trained.

The waste materials are discarded via a conveyor belt 1 (see FIG. 1) into a container 2 which is designed as a lock. The upper lid 3 of the container is open, the lower closure 4 is closed. After the container has been filled, the upper lid is closed and the lower one opened, the waste materials falling into the shaft 5 ′ of the heating space 6. The container 2 is then loaded again after the closure 4 has been closed and the lid 3 has been opened. The waste materials located in the shaft 5 are moved to the melting chamber 8 by a traveling grate 7 of known design. In this way, the waste materials are heated and their organic components are burned. For this purpose, nozzles 9 are provided through which fuels and combustion agents are introduced into the heating space. The resulting combustion gases are evenly distributed over the heating chamber through channels not shown in the drawing and pass through the layer of waste materials, releasing their sensible heat. If the waste materials contain organic components, the imported fuel is burned with excess air. so that the free oxygen remaining in the combustion gases is used to completely burn out these components. If the organic constituents themselves are sufficient to heat the waste materials, the fuel supply is switched off and only combustion agent is introduced through the nozzles 9. Incineration agents can also be introduced into the layer of waste materials through the grate 7 in order to burn their organic constituents. For this purpose, combustion agents are blown in through line 10 below the grate.

The exhaust gases from the burned fuels and organic components of the waste materials pull through the channel 11 into the shaft 12. The waste materials heated in space 6 fall into the melting space 8, where they are melted under the action of hot flames and in a molten state through the opening 13 flow into a water bath 14, where they granulate and are constantly discharged by a scraper conveyor, not shown in the drawing. Fuels with preferably preheated combustion agents are introduced into the melting chamber through nozzles 15. The combustion gases immediately brush the preheated waste materials and are deflected at the slag discharge opening in order to prevent the slag from freezing at this point. The melting area is delimited at the top by a slag grate 16 , which lowers the temperature of the combustion gases passing through and retains entrained slag particles which flow back in molten form into the melting area.

Behind the slag grate, the exhaust gases from the melting and heating space and withdraw together through the shaft 12. The walls of the rooms or channels 6, 8, 11 and 12 are heating surfaces of a steam boiler system with natural and / or Forced throughput. The shaft 12 is designed as a radiation space in which the withdrawing Combustion gases give off part of their sensible heat. Is subordinate to him first a steam superheater 17 for superheating the steam generated in the boiler system, then a combustion agent preheater 18 and finally a feed water preheater 19. In these devices, the exhaust gases passing through are largely theirs sensible heat. The fuel consumption is reduced by preheating the combustion agent considerably reduced for the melting work. In general, one becomes a combustion agent preheater or use recuperators made of metallic materials of known design that Allow preheating temperatures to reach 800 "C. Higher forward temperatures up to around 1200 ° C and above enable regenerators made of refractory building materials in known execution.

The exhaust gases, now largely cooled down behind the feedwater preheater 19, generally below 200 ° C., are passed via line 20 into the dedusting device 21 of a known type, where the entrained airborne dust is almost completely separated. From the dedusting device, the exhaust gases can be conducted outside via an induced draft fan and chimney or directly via a chimney 22.

The airborne dust continuously separated in the hoppers 23 and 24 becomes pneumatically in a known manner by means of dust pumps through nozzles into the melting chamber 8, where it is melted down and discharged with the slag. As a carrier gas one uses air, combustion gases or even flammable gases when the process is operated with gaseous fuels.

The second embodiment according to FIG. 2 has a heating and melting room 30 and 31. The facilities upstream and downstream of these are have been omitted in the drawing and can be similar to those according to F i g. 1.

The waste materials fed into the shaft 32 are continuously fed to the melting chamber 31 by an inclined moving grate 33. Fuels and combustion agents are introduced into the heating space through nozzles 34 and their combustion gases are evenly distributed over the layer of waste materials through channels not shown in the drawing. Below the grate, incineration agents are fed through the line 35, which are dimensioned so that they completely burn the organic components of the waste materials. The combustion gases are drawn off into the shaft 37 below the vault 36 between the heating and melting chambers.

The heated waste materials fall into the melting chamber 31, the bottom 38 of which is shaped like a trough, so that a slag bath 39 is formed. The height of the slag bath is regulated by an overflow 40 through which the slag overflows as new is formed. It flows into a water bath 41, where it is granulated and continuously discharged by a known type of conveying device, not shown. A gas-tight closure of the melting space to the outside is achieved by the immersion nozzle 42.

Nozzles 43, through which fuel and preheated combustion agents are blown onto the slag bath 39, open into the melting chamber 31, so that it is set in turbulent motion. The preheated waste materials slide along the wall 44 into the slag bath and melt rapidly under the action of the hot flame and the moving slag. By appropriately metering the fuel and the combustion agent, more or less reducing flames can be achieved. The metal parts present in the waste material then melt without oxidizing and, as a result of their specific weight, which is higher than that of the slag, collect at the bottom of the trough, from where they can be withdrawn temporarily or continuously through the tap hole 45. In the case of more strongly reducing flames, metal oxides present in the waste materials can also be reduced to metals. If there are only small amounts of metal in the waste materials, which are not worth extracting, the fuels introduced into the smelting space are burned with an excess of combustion agent, as a result of which the metals oxidize and slag.

The combustion gases, which are sharply deflected by the slag surface, are drawn off through the shaft 37, where they mix with the exhaust gases from the heating chamber. In the case of a reducing mode of operation in the melting chamber, combustion agents are fed into the shaft 37 through nozzles 46 in order to post-burn all unburned constituents in the combustion gas. Example Urban waste has an average composition of 45% moisture, 25% combustible components and 30% inorganic components (ash). The lower calorific value is around 1200 kcal / kg. Hard coal with a lower calorific value of 7000 kcal / kg is used as fuel.

In a device according to the invention according to FIG. 1 is located a mechanical one for a daily throughput of around 100 t of urban waste in the heating room Grate with an area of around 10 square meters, which preheated 7660 Nm3 to 200 ° C per hour Air is blown. Only fuel and air are fed through the nozzles 9 when starting up blown to set the waste on fire. Thereafter are sufficient the combustible components of the garbage to start the fire in the heating room to keep.

Every hour, 1.25 t of hard coal with 10,500 Nm of air preheated to 450`C is blown into the melting room with a volume of around 6 m3 and burned. The airborne dust of about 150 kg per hour falling into the funnels 23 and 24 is also blown pneumatically into the melting chamber with 100 Nm3 of compressed air. 1.4.2m3 of feed water is fed to the boiler system.

The exhaust gases from the heating room come out at around 1200 ° C the melting room with around 1700 ° C in the shaft designed as a radiation room 12 of the boiler system. After further release of their sensible heat in the steam superheater 17, air preheater 18 and economizer 19 draw them with a temperature of around 200 ° C through the chimney.

The system produces 13.3 t of steam per hour with a voltage of 100 ata and a temperature of 480 ° C. Around 1.38 t of granulated material fall every hour Slag, which in most cases is ideal for building purposes. Should a component, e.g. B. CaO or SiO. " not be sufficiently available, so surcharges, z. B. lime or sand, in be introduced into the melting chamber.

The use of a melting room with a slag bath leaves one achieve very homogeneous slag. You are therefore left with a slag bath everywhere work where more valuable melt products, e.g. B. building materials, fertilizers, chemical or metallurgical raw materials. The decisive factor here is naturally the composition of the waste materials and the type of aggregate.

Claims (16)

Claims: 1. Method for incinerating solid waste materials, in which the waste materials are moved through a heating room and initially dried and heated, then fed to a melting chamber in which their incombustible Residues are melted by the introduction of fuels and from which the Melting material is discharged periodically or continuously, characterized in that that moved by the in the heating chamber essentially in the horizontal direction Layer of waste materials, evenly distributed in the direction of movement, hot combustion gases and, if necessary, combustion agents or, if there is a sufficient content of combustible ones Components only combustion agents are passed, which also in a known manner be introduced into the layer of waste materials perpendicular to the direction of movement can, and the heated residues in a melting chamber, preferably continuously, in a broad front, in which they have the effect of in a thin layer outflowing, through the immediate combustion of fine-grained solid or liquid or gaseous fuels with combustion agents resulting combustion gases exposed and the incombustible residues converted into the molten state be, with the exhaust gases from the heating and from the melting chamber after delivery Their heat for heating and melting are brought together and in a known manner can be deducted together. 2. The method according to claim 1, characterized in that that the sensible heat of the exhaust gases to preheat the combustion agent and / or used to generate steam or for another heat-consuming process will. 3. The method according to claim 1 or 2, characterized in that the through the flue gas entrained in a dust removal device of known design is deposited and returned to the melting chamber. 4. The method according to claim 1, 2 or 3, characterized in that from the residues of the waste materials and if necessary. melt products formed from the ashes of imported fuels (Slag) are collected in the bottom of the melting chamber, which is designed as a sump and form a slag bath, which in a known manner - by the flow energy of the fuels and combustion media introduced into the melting zone in a more turbulent manner Movement is maintained, the slag being continuously or through an overflow is withdrawn periodically through a tap hole as new melt products appear form. 5. The method according to claim 4, characterized in that the melted Metal parts of the waste materials through a tap hole in the bottom of the slag sump or be deducted in the side wall. 6. The method according to claim 5, characterized in that that the fuel supplied to the melting chamber burns with a lack of combustion agent will. 7. The method according to claim 6, characterized in that above the melting space Combustion agents are added to the evacuating gases. B. Method according to a of claims 1 to 4, characterized in that the introduced into the melting chamber Fuel is burned with excess combustion agent to the melting point To convert metal parts of the waste materials into metal oxides. 9. Procedure after a of the preceding claims, characterized in that the melting chamber suitable Supplements are added to the melting point, viscosity or composition to change the slag. 10. Device for performing the method according to Claim 1, characterized by a conveyor device (7) of known type for ongoing transport of waste materials through the heating space (6) in the direction of the Melting space (8) and distribution channels in the heating space, which are in connection with a Firing for solid, liquid or gaseous fuels (9) are available and through the the combustion gases of the furnace possibly with an excess of combustion agents or through which only incineration agents are fed into the layer of waste materials, and nozzles (15) for the introduction of fuels and means of combustion into the melting chamber (8), which are preheated to the preferably continuously introduced Waste materials are directed (Fig. 1). 11. The device according to claim 10, characterized in that the conveying device (7) consists of a traveling or moving grate, through which combustion agents are passed into the layer of waste materials (Fig. 1). 12. The device according to claim 10 and for performing the method according to claim 4, characterized in that the nozzles (43) for fuels, combustion agents and additives in the melting chamber (31) are directed obliquely in the same direction and at a short distance to the slag bath (39) ( Fig. 2). 13. Device according to one of claims 10 to 12, characterized by nozzles for the introduction of combustion agents in the gas outlet of the melting chamber (8 or 31) and / or heating chamber (6 or 30, FIG. 1 or 2). 14. Device according to one of claims 10 to 13, characterized by openings or nozzles for the introduction of additives in the melting chamber (8 or 31, FIG. 1 or 2). 15. Device according to one of claims 10 to 14, characterized by a dedusting device (21) arranged between or downstream of the heat exchangers (17, 18, 19 ) and by a conveying device of known type and nozzles for returning the separated fly ash into the melting chamber (8, Fig. 1). 16. Device according to one of claims 10 to 15, characterized in that the heating chamber (6 or 30), melting chamber (8 or 31), channel (11 or 36) and shaft (12 or 37) for the discharge of the exhaust gases are components of a steam boiler system, in whose double jacket or pipe system the water to be evaporated is heated in natural circulation and / or forced flow (Fig. 1 or 2). Considered publications: German Patent Nos. 959 399, 123 239, 465 991; German Auslegeschrift No. 1007 932; Swiss patents No. 46 295, 300 512; “Das Papier” magazine, December 1952, p. 493, fig. 7.