AU5405000A

AU5405000A - Method and device for disposing of waste products

Info

Publication number: AU5405000A
Application number: AU54050/00A
Authority: AU
Inventors: Gunter H Kiss
Original assignee: Thermoselect AG
Current assignee: Thermoselect AG
Priority date: 1999-06-22
Filing date: 2000-06-15
Publication date: 2001-01-09
Anticipated expiration: 2020-06-15
Also published as: JP4445175B2; ES2195901T3; PT1187891E; ATE239775T1; KR20020012289A; EP1187891B1; AU777849B2; WO2000078896A1; DE19928581A1; DE50002089D1; KR100679781B1; DE19928581C2; JP2003503171A; EP1187891A1

Abstract

The invention relates to a method and a device for the disposal and utilisation of all types of waste products, for example, for the disposal of industrial, domestic or special waste and industrial scrap. The invention relates, in particular to the production of a stream of synthesis gas with a constant volume flow and a constant hydrogen content. According to the invention, the waste products are subjected phase by phase to different temperatures and to thermal separation or thermal substance transformation; the resultant solid residue is then converted into a high-temperature melt. The waste products to be eliminated are compressed in batches into compact packages and pass through the thermal treatment phases which increase progressively in temperature. This process comprises at least one lower temperature phase, in which the exerted pressure and a positive-fit and force-fit contact are maintained with the walls of the reaction vessel. In a high-temperature zone (20), the waste to be eliminated forms a gas-permeable bulk and a synthesis gas is produced. According to the invention, the hydrogen content or the volume flow of the derived synthesis gas is determined in said derived synthesis gas and is regulated by the supply of oxygen (104) or combustion gases.

Description

5 Method and device for the disposal of waste products The present invention relates to a method and a device 10 for the disposal and utilisation of all types of waste products, in which unsorted, untreated industrial, domestic and special waste, containing any kind of harmful substances in solid and/or liquid form, as well as industrial scrap are subjected to different 15 temperatures in accordance with the preamble of patent claim 1 or respectively of patent claim 16. The known methods of waste disposal do not form any satisfactory solution to the growing refuse problems which are a substantial factor in the destruction of 20 the environment. Industrial scrap formed from composite materials, such as motor vehicles and household appliances, but also oils, batteries, lacquers, paints, toxic sludge, medicines and hospital waste are subject to special disposal measures which 25 are strictly prescribed by law. Domestic waste, on the other hand, is an uncontrolled heterogeneous mixture which can contain practically all 2 kinds of special waste fractions and organic constituents and is not graded in respect of this disposal in any relation to its impact on the environment. 5 One of the methods of disposing and recovering waste products is the incineration of refuse. In known refuse incineration plants, the goods for disposal pass through a broad temperature field of up to approximately 1000'C. At these temperatures, mineral 10 and metal residues are supposed not to be melted, in order not to interfere with subsequent gas production phases. The energy inherent in the remaining solid materials is either not used or only unsatisfactorily used. 15 A short dwell time of the refuse at higher temperatures and the high development of dust caused by the addition of large amounts of nitrogenous combustion air to the uncompacted, incinerated waste products favour the dangerous formation of chlorinated hydrocarbons. 20 Therefore there has been a move towards subjecting the waste gases from refuse incineration plants to later combustion at higher temperatures. In order to justify the high investments in such plants, the abrasive and corrosive hot waste gases with their high proportion of 25 dust are led through heat exchangers. During the relatively long dwell time in the heat exchanger, chlorinated hydrocarbons form anew which combine with the included dusts and finally lead to stoppages and function impairments and have to be disposed of as 30 highly toxic substances. The resulting damages and the costs of their elimination cannot be estimated. Previous pyrolysis methods in conventional reactors have a broad temperature spectrum similar to that of refuse incineration. In the gasification zone there 35 are high temperatures. The hot gases forming are used 3 to preheat the waste to be eliminated which has not yet been pyrolysed, in so doing cool and pass also through the temperature range relevant for the new formation of chlorinated hydrocarbons and thus dangerous. In order 5 to produce pure gas which can be used in a manner that is ecologically harmless, pyrolysis gases generally pass through a cracker before purification. The prescribed incineration and pyrolysis methods have in common the disadvantage that the fluids or solid 10 materials which are vaporised during incineration or pyrolytic degradation are mixed with the combustion or pyrolysis gases and led away before they have reached the necessary temperature and dwell time in the reactor to destroy all the harmful substances. The vaporised 15 water has not been made utilisable for forming water gas. Therefore, as a general rule, in refuse incineration plants subsequent combustion chambers and in pyrolysis plants cracker phases are added. From EP 91 11 8158.4 is known a method for the disposal 20 and utilisation of waste products which avoids the above depicted disadvantages. Here the waste products are subjected to stepped temperatures and to thermal separation or substance conversion and the solid residues which occur are converted into a high 25 temperature melt. To this end, the waste products to be eliminated are compressed in batches to form compact packages and pass through the thermal treatment phases which increase progressively in temperature from a low-temperature 30 phase in which the application of pressure and a positive-fit and force-fit contact with the walls of the reaction vessel are maintained and organic constituents are degasified, to a high-temperature zone in which the degasified waste forms a gas-permeable 35 bulk and synthesis gas is produced through the 4 controlled addition of oxygen. This synthesis gas is then led out of the high-temperature zone and can be put to further use. What is disadvantageous about this method is that the 5 usability of the synthesis gas is limited by its chronologically altering composition. Thus, for example, in hydrogen generators the complete incineration of the hydrogen produced is only achieved if the hydrogen content of the supplied combustion gas 10 is constant within small limits. Otherwise, hydrogen motors tend for instance to knock. Furthermore, the volume flow of the synthesis gas produced fluctuates in this known method in dependence on the composition of the refuse and the therefore differing management of 15 the incineration process. The object of the present invention is, therefore, proceeding from the mentioned method, so to improve the latter that an economic and interruption-free utilisation of the synthesis gas obtained becomes 20 possible. This object is achieved by the method according to the preamble of claim 1 and by the device according to the preamble of claim 16 in conjunction with their respective characterising features. Advantageous developments of the method according to 25 the invention and the device according to the invention are given in the dependent claims. The method according to the invention continues the method disclosed in EP 91 11 81158.4, the disclosure of this document in respect of the methods and the device 30 being hereby completely included in the disclosed content of this application. The method described there and the device described there are now developed according to the invention in that the concentration of the hydrogen in the derived synthesis gas and/or the 35 volume flow of the derived synthesis gas are/is 5 detected and controlled. In this way, the use of the synthesis gas obtained from this refuse recycling method is possible for different applications in the chemical industry or respectively in thermal 5 utilisation. Thus this synthesis gas can be used without any problem in hydrogen engines. The water content can be measured for example by measuring the pressure loss during the volume flow which is conversely proportional to the volume flow 10 itself. If the hydrogen content is too high, oxygen can be injected via oxygen lances into the gas phase of the high-temperature zone above the bulk, by which means additional combustion of the hydrogen occurs and the hydrogen content in the synthesis gas drops. The 15 reverse adjustment is naturally also possible through the addition of combustible gas. Also the volume flow, which depends on the composition of the refuse and thus on the differing incineration thereby caused, can be adjusted by different amounts of fuel, such as natural 20 gas or synthesis gas for example, being introduced into the high-temperature zone. The synthesis gas can here be the synthesis gas produced in the method itself. Altogether through this development of the known Thermoselect method, there arises the possibility of 25 the exploitation of the hydrogen content for utilisation as material and energy for example in gas engines or fuel cells. For the latter applications, the concentration of hydrogen is adjusted ideally to approximately 35 % by 30 volume and the volume flow to approximately 1000 to 1600 Nm 3 in relation to a throughput of 1 Mg waste. Ideally the content of hydrogen and/or the volume flow of the derived synthesis gas after the purification of the synthesis gas is determined only after the sudden 35 cooling, which prevents the new formation of harmful 6 substances during the cooling phase of the synthesis gas. By this means, the actual content of hydrogen and/or the volume flow of the derived synthesis gas emitted to the outside are/is adjusted. 5 This rapid gas cooling (quench) comes about advantageously through the spraying of cold water, for example in temperature-stabilised water circulation systems, into the derived synthesis gas stream, by which means the synthesis gas is cooled suddenly and 10 furthermore the dust particles are removed from the synthesis gas mixture. The volume flow of the synthesis gas mixture can also be adjusted in that, at the outlet for the synthesis gas mixture for further use, a throttle device is 15 disposed, for example a controllable throttle valve. Several examples of the method according to the invention are given below. The figures show: Fig. 1 the sequence of the method according to the 20 invention in a schematic block diagram; Fig. 2 the characteristic method parameters of an embodiment; Fig. 3 a schematic section through a device for implementing the method according to the 25 invention. In Fig. 1 are symbolised method steps 1) to 8) . The waste is supplied without pre-treatment, i.e. without sorting and without being broken up, to phase 1) in which it is compacted. The compaction result is 30 considerably improved here if pressing surfaces act in 7 both vertical and horizontal directions. High compression is necessary, since the feeding aperture of the stoking channel in which method step 2) takes place, is sealed gas-tight by the highly compressed 5 plug of waste. The highly compressed waste passes through the channel of phase 2) with the exclusion of oxygen at temperatures of up to 600"C. Organic constituents of the waste are degasified. The gases flow through the 10 waste products located in the furnace in the direction of method phase 3). As they flow, they contribute to good heat transfer as does the intensive pressure contact of the waste with the furnace walls. As a result of the constant pushing down of the highly 15 compressed waste, this pressure contact is maintained over the whole length of the furnace and the entire surfaces of the channel, such that after the waste has passed through the stoking channel, the degasification of the organic substances is largely completed. 20 Carbonisation gases, water vapour such as stems from the natural humidity of the waste, metals, minerals and the carbon of the degassed organic products are supplied together to method phase 3) in which first of all the carbon is combusted with oxygen. The 25 temperatures arising here of up to 2000'C and more melt the metal and mineral constituents, such that they can be discharged molten in method step 6). Parallel to this, above the high-temperature region of the glowing carbon bed at temperatures of more than 30 1200 0 C, the organic compounds of the carbonisation gases are destroyed. As a result of the respective reaction equilibrium of C, C0 2 , CO and H 2 0 at these temperatures, synthesis gas is formed consisting substantially of CO,

H

2 and C0 2 , which is cooled abruptly in method step 4) 35 to temperatures of below 100 0 C. The rapid cooling 8 prevents the new formation of organic harmful substances and renders easier the gas washing provided in phase 5). The extremely pure synthesis gas is then available for any application. 5 The extremely pure synthesis gas can, in the method to this extent known, have a volume flow dependent on the composition and amount of waste product and also a varying concentration of hydrogen. Therefore, after the gas washing 5), the volume flow and the hydrogen 10 content of the purified synthesis gas are determined and these values are supplied to a control system 9). This control system now controls, as described above, the supply of oxygen and the supply of fuel, for example natural gas or synthesis gas, to method phase 15 3) in which the previously degasified waste is gasified at temperatures of up to 20000C through the addition of 02. Through this alteration of the introduction of fuel or the supply of oxygen, both the volume flow and the hydrogen content of the synthesis gas arising can be 20 influenced. Through this regulation, therefore, a flow of synthesis gas with controlled constant volume flow and also controlled constant hydrogen content is available for gas recovery following the gas washing 5). 25 The metals and mineral substances discharged molten in method step 6) are subjected expediently in method step 7) to after-treatment with the addition of oxygen at more than 14000C. In this process, carbon residues which have been carried along are eliminated and 30 mineralisation is terminated. The discharge of the solids, for example into a water bath, terminates in method step 8) the disposal process. In the granulate obtained after the discharge of the solids into a water bath, are to be found beside one another metals and 35 alloy elements and completely mineralised non-metals. Iron alloys can be magnetically deposited. The non- 9 metals, mineralised so that they do not leach, can be used again in many ways, for example in expanded granulate form or - processed into rock wool - as insulating material or directly as granules for fillers 5 in road construction and in the production of concrete. Fig. 2 shows a greatly schematised representation of a device for carrying out the method of the invention. To the individual regions are allocated typical process data of an advantageous implementation of the method, 10 by way of example. The degasification is a function of the temperature T, of the pressure and of the composition of the waste. The composition and the volume flow now depend on the carbon, oxygen and water vapour present. As the amount 15 of available carbon (fuel supply to the gas phase) and oxygen (oxygen supply via oxygen lances to the gas phase) is controlled, the composition of the synthesis gas, which already has a relatively high quality in the known method, is further optimised and is therefore 20 ideally suited to be used e.g. for converting into electric energy in gas engines, or for chemical processes. In Fig. 3 the compression press 1 corresponds in its structure to a scrap press, known per se, such as is 25 used e.g. for the scrapping of vehicles. The pivotable pressing plate 2 makes possible the loading of the press 1 with mixed waste, shown here vertical (broken line). The pressing surface 3 is located in the left hand position, so that the charging chamber of the 30 press is completely open. By swivelling the pressing plate 2 into the horizontal position illustrated, the waste is first of all compressed in a vertical direction. Thereafter, the pressing surface 3 moves horizontally into the position shown in an unbroken 35 line and compresses the waste package in a horizontal 10 direction. The counter-forces required for this purpose are absorbed by the counter-plate 9 which can be moved in and out in the direction of the arrow. After the compression process is completed, the 5 counter-plate 9 is moved out and the compressed plug of waste is pushed with the aid of pressing surface 3, which is moving further towards the right, into the unheated region 5 of the furnace 9 and thus its total content is correspondingly conveyed further, compressed 10 again and held in pressure contact with the channel wall or furnace wall. Then pressing surface 3 is moved back into the left-hand end position, the counter-plate 9 is moved in and pressing plate 2 is swung back into the vertical position represented in a broken line. 15 The compression press 1 is ready to be charged again. The compression of the waste is so great that the waste plug pushed into the unheated region 5 of the furnace 6 is gas-tight. The furnace is heated by combustion and/or waste gases, which flow through the heating 20 jacket 8 in the direction of the arrow. As the compressed waste is pushed through the furnace channel 6, the degasified zone 7 expands in the manner illustrated towards the central plane of the furnace 6, favoured by the large surface connected with the 25 side/height ratio >2 of its rectangular cross-section. On entry into the high-temperature reactor 10, a compacted mixture of carbon, minerals and metals is present as a result of the constant application of pressure as it is pushed through. This mixture is 30 exposed to very great radiation heat in the region of the entry aperture into the high-temperature reactor. The sudden expansion, connected therewith, of residual gases in the smouldering goods leads to said goods disintegrating into pieces. The solid pieces thus 35 obtained form a gas-permeable bed 20 in the high temperature reactor, in which bed the carbon of the smouldering product is incinerated with the aid of 11 oxygen lances 12, to form at first CO 2 or respectively CO. The carbonisation gases flowing turbulently through the reactor 10 above bed 20 are completely detoxicated by cracking. Between C, CO 2 , CO and the 5 water vapour driven out of the waste, a temperature dependent reaction equilibrium is set during the formation of synthesis gas. The temperatures arising correspond to the illustration of Fig. 2. The synthesis gas is cooled abruptly in container 14 by 10 water injection to less than 100 0 C. Constituents carried along in the gas (minerals and/or metal in molten state) are deposited in the cool water, water vapour is condensed, such that the gas volume is reduced and this renders easier the gas purification 15 which can follow the abrupt cooling in arrangements which are known per se. After purification, the water used for the abrupt cooling of the synthesis gas flow can possibly be used again for cooling, after purification. 20 The hydrogen content and the volume flow are regulated by means of a sensor 100 disposed in the derived synthesis gas flow and which passes signals via a line 102 to a control device 101. The signals contain both the current volume flow and the current hydrogen 25 content of the cooled, purified and derived synthesis gas flow. The control system now alters, by means of the control signal line 103 which is disposed between the control system 101 and an oxygen lance 104, the supply of oxygen through oxygen lance 104 to the gas 30 phase above the bulk 20. By increasing the supply of oxygen, an increased combustion of H 2 and thus a lower hydrogen content in the synthesis gas can be produced. By reducing the supply of oxygen via oxygen lance 104, the combustion in the gas phase is reduced and thus the 35 hydrogen content in the synthesis gas increases. If the volume flow of the synthesis gas is not adequate, the supply of combustible gases, such as for example 12 natural gas or synthesis gas itself, to the bulk 20 or also to the gas phase, can be increased or reduced. Thus the content of hydrocarbons in the reactor is altered and consequently the whole synthesis gas volume 5 flow is influenced. In the core region, heated to more than 2000"C, of bed 20, the mineral and metal constituents of the smouldering product are melted. As a result of the differing density they are layered the one above the 10 other and de-mix. Typical alloy elements of iron, such as for example chromium, nickel and copper, form with the iron of the waste a treatable alloy, oxidise other metal compounds or aluminium and stabilise as oxides the mineral melt. 15 The melts enter directly into the after-treatment reactor 16, in which, in an oxygenous atmosphere introduced with the aid of the 02 lance 13, possibly supported by gas burners not shown, they are exposed to temperatures of more than 1400 0 C. Carbon particles 20 which have been carried along are oxidised, the melt is homogenised and its viscosity reduced. During their common discharge into the water bath 17, mineral substances and iron melt form separate granules and can thereafter be sorted magnetically. 25 In Fig. 3, the position of the after-treatment reactor 16 is drawn offset by 90 for reasons of clarity. This reactor 16 forms with the lower part of the high temperature reactor 10 a structural unit which, after a flange connection 10' has been detached, can be moved 30 sideways out of the line of the device for maintenance and repair purposes. The line of the device disposed, as shown in Fig. 3, substantially in alignment, extends over a considerable 13 length. Changing temperatures - above all when the system is fired up or down into or out of thermal equilibrium - lead to considerable thermal expansion. In the stationary arrangement of the high-temperature 5 reactor 10, this is allowed for in respect of the furnace 6 and the connected compression press 1 by rollers 4 which, running in guide rails (not shown) not only render possible longitudinal movements but can also absorb side forces. In the pipelines (for example 10 15) going from the high-temperature reactor, expansion joints 11 compensate for the expansion.

Claims

1. Method for the disposal and utilisation of all types of waste products, in which unsorted, 5 untreated industrial, domestic and/or special waste, containing any kind of harmful substances in solid and/or liquid form, as well as industrial scrap are subjected to stepped temperatures and to thermal separation or thermal substance 10 transformation and the resultant solid residue is then converted into a high-temperature melt, wherein the waste products to be eliminated are compressed in batches into compact packages and pass through the thermal treatment phases in the 15 direction of increasing temperature with at least one low- temperature phase in which the application of pressure and a positive-fit and form-fit contact with the walls of the reaction vessel are maintained, and with at least one high 20 temperature zone in which the waste to be eliminated forms a gas-permeable bulk and synthesis gas is produced, the produced synthesis gas being led away from the high-temperature zone, characterised in that 25 the concentration of hydrogen in the derived synthesis gas and/or the volume flow of the derived synthesis gas is regulated.

2. Method according to claim 1, characterised in that 30 the concentration of hydrogen in the derived synthesis gas is adjusted to a value which is to be regarded as constant.

3. Method according to one of claims 1 to 2, 35 characterised in that the concentration of 15 hydrogen in the derived synthesis gas is adjusted to approx. 35% by volume.

4. Method according to one of the preceding claims, 5 characterised in that oxygen is introduced in addition to the high-temperature phase in dependence on the hydrogen content in the derived synthesis gas. 10

5. Method according to the preceding claim, characterised in that the oxygen is introduced to the high-temperature phase by means of oxygen lances. 15

6. Method according to one of the two preceding claims, characterised in that the oxygen is introduced in a pulsed manner.

7. Method according to one of the preceding claims, 20 characterised in that the volume flow of the synthesis gas is adjusted to a value of approx. 1000 to 1600 Nm 3 in relation to a throughput of 1 Mg waste for disposal. 25

8. Method according to one of the preceding claims, characterised in that fuel is introduced in addition to the high-temperature phase, in dependence on the volume flow. 30

9. Method according to one of the preceding claims, characterised in that at least the low-temperature is passed through with the application of pressure maintained in positive-fit and force-fit contact with the walls of the reactor vessel, oxygen being 35 excluded. 16

10. Method according to one of the preceding claims, characterised in that the low-temperature phase is passed through in the temperature range between 5 100 0 C and 600 0 C.

11. Method according to one of the preceding claims, characterised in that the high-temperature phase is passed through with the addition of oxygen. 10

12. Method according to the preceding claim, characterised in that the carbon components in the bulk are gassed through the metered addition of oxygen to form carbon dioxide and carbon monoxide, 15 the carbon dioxide being reduced to carbon monoxide as it penetrates through the carboniferous bulk, and in that hydrogen and carbon monoxide are produced from the carbon and the greatly heated water vapour. 20

13. Method according to one of the preceding claims, characterised in that the high-temperature phase is passed through at temperatures of more than 10000C. 25

14. Method according to one of the preceding claims, characterised in that the derived synthesis gas is subjected, directly after leaving the high temperature reactor, to the sudden application of 30 water until it cools to below 100'C and is freed of dust in the process.

15. Method according to one of the preceding claims, characterised in that the content of hydrogen 35 and/or the volume flow of the derived synthesis 17 gas is determined after the abrupt cooling and the content of hydrogen and/or the volume flow of the derived gas correspondingly regulated. 5

16. Device for the preparation, transformation and after-treatment of all types of waste products, having a plurality of thermal treatment phases which include at least one low-temperature phase with oxygen excluded and at least one high 10 temperature phase with oxygen supplied at temperatures above 1000'C, and having an outlet for the synthesis gas mixture produced in the high-temperature phase, wherein all the reaction chambers of the treatment phases are securely 15 inter-connected without any locks, and devices for feeding oxygen and devices for feeding fuel are provided in the high-temperature phase, characterised in that at the outlet for the synthesis gas mixture are 20 disposed sensors to determine the content of hydrogen and/or for the volume flow of the synthesis gas mixture, which are connected to a device for controlling the amount of oxygen and/or fuel supplied. 25

17. Method according to the preceding claim, characterised in that the gas exit side of the high-temperature phase is connected to a rapid gas-cooling system which has a device for 30 injecting cold water into the hot flow of the synthesis gas mixture.

18. Device according to one of the two preceding claims, characterised in that the outlet for the 18 synthesis gas mixture has a throttle device, for example an adjustable throttle valve.

19. Device according to one of claims 16 to 18, 5 characterised in that a device for gas purification is positioned in front of or after the outlet for the synthesis gas mixture.

20. Device according to one of claims 16 to 19, 10 characterised in that a device for utilising gas, for example a gas motor/generator combination, a gas turbine, a steam generator or the like is arranged after the outlet for the synthesis gas mixture. 15

21. Device according to one of claims 16 to 20, characterised in that the reaction chamber for the low-temperature phase is a furnace of rectangular cross-section which is disposed horizontally and 20 heated externally and of which the ratio furnace width to furnace height is greater than two, the furnace length being give by the relationship Lfurnace 15 Ffurnace, with Ffurnace as the cross sectional area of the furnace. 25

22. Device according to one of claims 16 to 21, characterised in that the reaction chamber for the high-temperature phase is configured as a vertical shaft furnace to which, above its base, the 30 reaction chamber for the low-temperature phase is coupled without interruption.

23. Use of a device according to one of claims 16 to 22, characterised in that after the separation or 35 conditioning of the synthesis gas, hydrogen is 19 used in hydrogen motors or fuel cells and/or the synthesis gas is used as a substance.