AU3728701A

AU3728701A - 2-stage cooling process for synthesis gas

Info

Publication number: AU3728701A
Application number: AU37287/01A
Authority: AU
Inventors: Gunter H Kiss
Original assignee: Thermoselect AG
Current assignee: Thermoselect AG
Priority date: 2000-01-31
Filing date: 2001-01-11
Publication date: 2001-08-14
Also published as: DE50101983D1; EP1252264B1; ES2217119T3; EP1252264A1; WO2001057161A1; JP2003522020A; ATE264382T1; DE10004138C2; JP4615176B2; DE10004138A1; KR20020075785A

Abstract

The invention relates to a method for the disposal and the utilization of waste products of any kind. According to the inventive method, industrial, household and/or hazardous wastes that contain unsorted, untreated, harmful substances of any kind in solid and/or liquid form, as well as wracks of industrial commodities are subjected to a step-wise thermal treatment and thermal separation or physical transformation. The solid residues obtained by this method are liquefied at high temperatures. The inventive method is further characterized in that the discharged synthesis gas, once it has left the high-temperature reactor, is subjected to a shock treatment with water to cool off to 150 DEG C to 200 DEG C and then to a second shock treatment with water until it is cooled off to less than 90 DEG C. After the first step, the batch contained in the synthesis gas is transformed to hydrogen sulfide in the presence of water vapor and the hydrogen sulfide is then removed by means of iron chelate in a gas purification step.

Description

1 2-stage Cooling Process for Synthesis Gas The present invention relates to a method and a device for disposal and utilisation of waste materials of all kinds in which ungraded, untreated, industrial, domestic and/or special waste, which contain any pollutants in a solid and/or liquid form, and also industrial scrapped goods, are subjected to a step-wise temperature application and to thermal separation or material conversion. The invention relates in particular to a method for avoiding the emission of COS in the waste gases released into the environment. The present invention relates furthermore to a device which is suitable for the above method. The known methods for waste disposal offer no satisfactory solution to the increasing waste problems which are a substantial factor in environmental destruction. Industrial scrapped goods made of composite materials, such as automotive vehicles and household appliances but also oils, batteries, enamels, paints, toxic sludges, medicines and hospital waste, are subject to separate, legally strictly prescribed disposal measures. Domestic waste on the other hand is an unchecked heterogeneous mixture which can contain virtually all types of special waste fractions and organic components and, with respect to disposal, is still not classified in proportion to its environmental impact. One of the disposal and recovery methods for waste materials is refuse incineration. In the known refuse incineration plants, the disposal materials pass through a wide temperature field of up to approximately 1000 OC. At these temperatures, mineral and metallic residues are not intended to be melted in order as far as possible not to disrupt subsequent gas production stages. The inherent energy in the remaining solid materials is not used or only inadequately used. A short dwell time of the waste at higher temperatures and the high dust production due to the requirement for large quantities of high-nitrogen incineration air in the non compressed waste incineration materials encourages the 2 dangerous formation of chlorinated hydrocarbons. For this reason there has been a move therefore towards subjecting the waste gases from refuse incineration plants to a subsequent incineration at higher temperatures. In order to justify the high costs of such plants, the abrasive and corrosive hot waste gases with their high dust component are conducted through heat exchangers. During the relatively long dwell time in the heat exchanger, chlorinated hydrocarbons are reformed which combine with the entrained dusts and in the end lead to blockages and functional disruption and require to be disposed of as highly toxic pollutants. Subsequent damage and the costs of their elimination cannot be estimated. Current pyrolysis methods in conventional reactors have a broad temperature spectrum similar to refuse incineration. High temperatures prevail in the degassing zone. The self forming hot gases are used for preheating the not yet pyrolised disposal material, are hereby cooled and likewise pass through the temperature range which is relevant for the new formation of chlorinated hydrocarbons and hence is dangerous. In order to produce an ecologically safe usable pure gas, pyrolysis gases generally pass through a cracker before purification. The prescribed incineration and pyrolysis methods have in common the disadvantage that the liquids or solid materials, which are evaporated during incineration or pyrolytic decomposition, are mixed with the incineration or pyrolysis gases and are discharged before they have reached the temperature and dwell time in the reactor, which is necessary for destruction of all pollutants. The evaporated water is not made usable for water gas formation. For this reason, subsequent incineration chambers generally are connected subsequently in the case of refuse incineration plants and cracker stages are connected subsequently in the case of pyrolysis plants. A method for disposal and utilisation of waste materials is known from EP 91 11 8158.4 which avoids the above described disadvantages. The waste materials are thereby subjected to a step-wise temperature application and thermal separation or material conversion and the occurring solid residues are converted into a high temperature melt. For this purpose, the material to be disposed of is compressed into compact packets in batches and passes through the temperature 3 treatment stages in the direction of increasing temperature, from a low temperature stage in which, while maintaining the pressure application, a form-fitting and frictional contact is ensured with the walls of the reactor container and organic components are degassed, to a high temperature zone in which the degassed material for disposal forms a gas permeable bed and synthesis gas is produced by controlled addition of oxygen. This synthesis gas is discharged then from the high temperature zone and can be further utilised. This discharge of the crude synthesis gas of the high temperature reactor is for its part connected in a fixed manner to a gas chamber for rapid gas cooling which has a water injection device for cold water into the hot crude synthesis gas stream. This rapid gas cooling (shock cooling) prevents renewed synthesis of pollutants since the crude synthesis gas passes very quickly through the critical temperature range because of the shock cooling and is cooled to a temperature at which re-synthesis of the pollutants no longer takes place. This cold water injection into the crude synthesis gas stream in addition binds liquid or solid particles entrained in the gas stream so that, after rapid cooling, a well pre-cleaned crude synthesis gas is obtained. In the case of this plant described in EP 91 11 8158 .4, not only H 2 S but also traces of COS are formed from the sulphur components contained in the waste, which leave the gasification region in a gaseous form with the formed synthesis gas. The H 2 S components present in the crude synthesis gas are subsequently absorbed in a gas wash with iron chelate and oxidised into elementary sulphur and as a result removed from the crude synthesis gas, whilst the COS is only partly bonded by the iron chelate and/or is decomposed. The non absorbed COS remains in the synthesis gas and, during the subsequent, for example thermal use of the synthesis gas, is transformed into SO 2 and is discharged into the atmosphere as a pollutant. It is therefore the object of the present invention to propose a method and a device by means of which the disposal and utilisation process according to the invention can be implemented without noxious emissions of SO 2

.

4 This object is achieved by the method according to claim 1 and the device according to claim 12. Advantageous developments of the method according to the invention and of the device according to the invention are given in the respective dependent claims. The method according to the invention follows in content the method disclosed in EP 91 11 8158.4, the disclosure of this publication being herewith included entirely in the disclosure content of this application with respect to the method and to the device. According to the invention, the above-mentioned pollution burden is avoided by subjecting the synthesis gas produced in the high temperature reactor to a 2-stage shock-like water application for cooling. In a first shock-like cooling, the synthesis gas is cooled to a temperature between 150 0 C to 200*C and remains there for a predetermined time. Subsequently, a further shock-like water application is effected until cooling below 90'C. Because of the shock-like cooling, the reformation of dioxins and furanes in the synthesis gas is excluded. As a result of the fact that the synthesis gas is cooled in a first stage to a temperature between 150 0 C and 200 0 C, the COS contained in the synthesis gas is subsequently transformed into hydrogen sulphide in the presence of water vapour according to the following equation COS + H 2 0 -+ CO 2 + H 2 S In order to achieve this transformation, enough water, dependent upon the gas volume, is injected advantageously into the gas flow in a first cooling stage such that the gas is cooled in a shock-like manner to the mentioned temperature between 150 0 C and < 200 0 C. Because of this injection of cooling water the cooled crude synthesis gas already contains the high proportion of water vapour required for conversion of COS in order to transform COS into H 2 S. Subsequently, the end temperature of the crude synthesis gas is accomplished below 90*C by a second shock-like water cooling by means of injection of cooling water.

5 Since hydrogen sulphide is now present in the crude synthesis gas and this is removed in a subsequent gas purification stage by means of iron chelate, the crude synthesis gas subsequently contains no significant COS-H 2 S components. During the subsequent thermal usage of the crude synthesis gas, the formation of SO 2 is hence also avoided and the waste gas from the thermal usage is freed of otherwise normal S02 components. The water injection is effected ideally in both stages of the rapid cooling by means of a multiplicity of nozzles which can be switched on or off. In this case, the water quantity injected into the synthesis gas can be controlled via regulation of the switching on or off of the individual nozzles in such a manner that the desired end temperatures of the synthesis gas are achieved between 150*C and 200*C for the first water cooling or < 90*C for the second water cooling. A few examples of the method according to the invention and the device according to the invention are described subsequently. There are shown Fig. 1 a device according to the invention; and Fig. 2 a rapid gas cooling according to the invention. Fig. 1 shows a device according to the invention for material reprocessing, material conversion and material subsequent treatment with a high temperature reactor 10. It is illustrated in Figure 1 how residual waste is introduced into a compacting press. The compression is thereby effected by a compacting press 1 which corresponds in its construction to a waste refuse press which is known per se, as is used for example for scrapping vehicles. A pivotable pressing plate 2 makes it possible to supply the press 1 with mixed waste. A pressing face 3 is located in the left-hand position so that the supply space of the press is fully opened. By swivelling the pressing plate 2 into the illustrated horizontal position, the waste is initially compacted in a vertical direction. After that, the pressing face 3 is moved horizontally into the position illustrated in the continuous line layout and compacts the waste packet 6 in the horizontal direction. The counter-forces required for this purpose are absorbed by a non-illustrated counter plate which can be moved in and out. After the compacting process has been completed, the counter-plate is moved out and the compacted waste plug is inserted by means of the pressing face 3, which is moved further to the right, into an unheated region 5 of the batch furnace 6 and thus its entire content is correspondingly transported further, recompacted and held in pressure contact with the channel or furnace wall. Next the pressing face 3 is moved back into the left-hand end position, the counter-plate is moved in and the pressing plate 2 is swivelled back into the vertical position illustrated in broken lines. The compacting press 1 is ready for reloading. The waste compression is so great that the plug of waste inserted into the unheated region 5 of the batch furnace 6 is gas-impermeable. The heating of the batch furnace is effected by flame and/or waste gases which flow through a heating sleeve 8 in the direction of the arrow. When pushing the compacted waste through the furnace channel 6, a degassed zone extends towards the central plane of the batch furnace 6, assisted by the large surface connected with the side/height ratio > 2 of its rectangular cross section. Upon entry into a high temperature reactor 10, a mixture of carbon, minerals, metals and partly decomposed degassing-capable components occurs, said mixture being compacted by constant pressure application whilst being pushed through. This mixture is subjected in the region of the entry opening into the high temperature reactor 10 to extremely high radiation heat. The sudden expansion of residual gases in the carbonisation item involved herewith leads to its reduction into lumps. The solid material unit load obtained thus forms a gas-permeable bed 20 in the high temperature reactor, in which bed the carbon of the carbonisation item is incinerated by means of oxygen lances 12 initially into CO 2 or CO. The carbonisation gases flowing above the bed 20 through the reactor 10 during turbulence are detoxified entirely by cracking. Between C, C0 2 , CO and the water vapour expelled from the waste, a temperature conditioned reaction equilibrium is set during synthesis gas formation. In the core region of the bed 20 which has a temperature of more than 2000 *C, the mineral and metallic components of the carbonisation item are melted. Because of the different 7 density, they thereby cover each other and are mixed. Typical alloy elements of iron, such as for example chrome, nickel and copper, form with the iron of the waste, a treatable alloy, other metal compounds, for example aluminium, oxidise and stabilise the mineral melt as oxides. The melts enter directly into a subsequent treatment reactor 16 in which they are subjected to temperatures of more than 1400 0 C in an oxygen atmosphere introduced by means of an 02 lance 13, if necessary assisted by non-illustrated gas fuel burners. Entrained carbon particles are oxidised, the melt is homogenised and lowered in its viscosity. During their common discharge into a water bath 17, mineral matter and iron melt granulate separately and can subsequently be graded magnetically. The crude synthesis gas produced in the upper part of the high temperature reactor 10, which forms a stabilisation region, is conducted via a crude synthesis gas pipe 30 to a container or chamber 14 in which the synthesis gas is cooled in 2-stages by water injection in a shock treatment to less than 900C. Any components entrained in the gas (minerals and/or metal in a molten state) are deposited in the cooling water, water vapour is condensed so that the gas volume is reduced and thus the gas purification is facilitated which can follow shock cooling in arrangements which are known per se. The water used for shock-type cooling of the synthesis gas flow can if necessary be used once again for cooling after purification, for example in a settler 32, and consequently be returned into the circulation. During rapid cooling of the crude synthesis gas by injection of cooling water into the crude synthesis gas flow, not only liquid components and solid material components (dusts etc.) are removed from the crude synthesis gas but also the cooling water absorbs in addition gas components from the crude synthesis gas. This is effected for example by emulsification of the ultra-fine gas bubbles in the cooling water or by dissolution of gases from the crude synthesis gas. In the chamber 14, cooling to below 901C is effected in a two-stage method. In a first stage, water is injected into the synthesis gas so that the synthesis gas is cooled to a temperature between 150 0 C and 200 0 C. Then the thus cooled synthesis gas remains at this temperature until the COS 8 contained in the synthesis gas is transformed into H 2 S. Subsequently, the second stage of the shock-like rapid cooling is effected by further injection of cooling water in order to cool the synthesis gas to below 90 C. The cooling water is conducted from the container 14 via a pipe 31 into a settling region, here a lamellar classifier 32, where the solid materials contained therein, for example floating components, are deposited and the contained gases are degassed from the cooling water. The thus purified cooling water is conducted back via a pipe 33 into the container 14 once again for cooling the crude synthesis gas and consequently is introduced into a circulation. The crude synthesis gas purified in the chamber 14 leaves the container 14 via a pipe 30a and is subjected subsequently to a fine wash or fine purification in washers 34, 34a, 34b and 34c. The washer 34a is thereby a washing stage in which the H 2 S is removed from the crude synthesis gas by means of iron chelate and can subsequently be discharged as pure sulphur. The thus finely purified synthesis gases can be supplied via a pipe 38 for use, for example in a gas generator 35, or else be supplied in the case of a fault to a combustion chamber with flue where they can be incinerated in an ecologically safe manner with the supply of forced air and be disposed of. Since the synthesis gas is free of COS and H 2 S, the waste gases from the synthesis gas usage, for example the waste gases of the gas generator 35, no longer contain significant sulphur dioxide components and are emission-free with respect to sulphur components. They can be released directly into the environment, i.e. without waste gas purification, via a chimney 36. Fig. 2 shows a chamber 14 with a 2-stage rapid cooling, the same elements in Fig. 2 being designated with the same reference numbers as in Fig. 1 and therefore not being described further. The still unpurified synthesis gases enter into the chamber 14 via the pipe 30 and a central pipe 101. Within the central pipe, a first water injection device 103 with water nozzles 105 is disposed. This water injection device 103 is 9 supplied with cooling water via a pipe 33a and sprays cooling water into the synthesis gas flow in the central pipe 101. By switching individual water nozzles 105 on and off, the water flow is thereby regulated such that the synthesis gases cooled by the cooling water have a temperature between 150*C and 200 0 C. The synthesis gas pipes thus cooled firstly in a shock-like manner to 150 0 C to 200 0 C flow along the central pipe 101, the COS contained in the synthesis gas being converted into H 2 S. Via the volume or the length of the central pipe 101, the dwell time of the synthesis gas can be controlled at 1500 to 200 0 C such that the synthesis gas only enters into the second stage of the rapid cooling when the COS contained is completely decomposed. At the end of the central pipe 101, the synthesis gas enters into the volume of the chamber 14 surrounding the central pipe 101 and there is sprayed with water via a second water injection device 104 with water nozzles 105a and is cooled in a shock-like manner to temperatures below 90*C. The water injection device 104 is thereby supplied with cooling water via a cooling water pipe 33b. The cooling water quantity sprayed here via the nozzles 105a is also controlled by means of switching the individual nozzles 105a off and on in such a manner that the temperature of the cooled synthesis gas lies below 90*C. Hence no renewed synthesis of dioxins or furanes can take place in the synthesis gas. The synthesis gas cooled thus to under 90 0 C leaves the chamber 14 via the pipe 30a in the direction of the gas fine washer 34 to 34c of Fig. 1. The chamber 14 has furthermore a sump 102 and an outlet pipe 31 via which the injected cooling water is collected and discharged (see Fig. 1).

9 supplied with cooling water via a pipe 33a and sprays cooling water into the synthesis gas flow in the central pipe 101. By switching individual water nozzles 105 on and off, the water flow is thereby regulated such that the synthesis gases cooled by the cooling water have a temperature between 150*C and 200 0 C. The synthesis gas pipes thus cooled firstly in a shock-like manner to 150 0 C to 200 0 C flow along the central pipe 101, the COS contained in the synthesis gas being converted into H 2 S. Via the volume or the length of the central pipe 101, the dwell time of the synthesis gas can be controlled at 1500 to 200 0 C such that the synthesis gas only enters into the second stage of the rapid cooling when the COS contained is completely decomposed. At the end of the central pipe 101, the synthesis gas enters into the volume of the chamber 14 surrounding the central pipe 101 and there is sprayed with water via a second water injection device 104 with water nozzles 105a and is cooled in a shock-like manner to temperatures below 90*C. The water injection device 104 is thereby supplied with cooling water via a cooling water pipe 33b. The cooling water quantity sprayed here via the nozzles 105a is also controlled by means of switching the individual nozzles 105a off and on in such a manner that the temperature of the cooled synthesis gas lies below 90*C. Hence no renewed synthesis of dioxins or furanes can take place in the synthesis gas. The synthesis gas cooled thus to under 90*C leaves the chamber 14 via the pipe 30a in the direction of the gas fine washer 34 to 34c of Fig. 1. The chamber 14 has furthermore a sump 102 and an outlet pipe 31 via which the injected cooling water is collected and discharged (see Fig. 1).

Claims

1. Method for disposal and utilisation of waste materials of all types in which ungraded, untreated, industrial, domestic and/or special waste, which contain any pollutants in a solid and/or liquid form, and also industrial scrapped goods are subjected to a step-wise temperature application and to thermal separation or material conversion and the occurring solid residues are converted into a high temperature melt, the item for disposal - compressed into compact packets in batches - passing through the temperature treatment stages in the direction of increasing temperature, with at least one low temperature stage in which, whilst maintaining the pressure application, a form-fitting and frictional contact with the walls of the reaction container is ensured, and with at least one high temperature zone, in which the item for disposal produces synthesis gas and forms a gas-permeable charge and also a stabilisation zone for the synthesis gas located above the charge, and the produced synthesis gas being discharged from the stabilisation zone, characterised in that, the discharged synthesis gas, directly after leaving the high temperature reactor, is subjected to a first shock-like water application up to cooling to 150 0 C to 200*C and subsequently to a second shock-like water application up to cooling below 90*C.

2. Method according to the preceding claim, characterised in that the discharged synthesis gas remains for a predetermined time at approximately 150 0 C to 200 0 C between the first and the second water application.

3. Method according to one of the preceding claims, characterised in that the water quantity used for the first and/or the second water application is controlled dependent upon the volume flow of the synthesis gas.

4. Method according to one of the preceding claims, characterised in that the application of water to the synthesis gas is effected via a multiplicity of nozzles.

5. Method according to the preceding claim, characterised in that the applied water quantity is varied by 11 switching on and off of individual nozzles while maintaining constant the quantity of water applied by each switched-on nozzle.

6. Method according to one of the preceding claims, characterised in that, subsequent to the second water application, the hydrogen sulphide (H 2 S) contained in the synthesis gas is removed from the synthesis gas by means of iron chelate.

7. Method according to one of the preceding claims, characterised in that, in normal operation, at least the low temperature stage is passed through with the exclusion of oxygen whilst maintaining the pressure application in form-fitting and frictional contact with the walls of the reactor container.

8. Method according to one of the preceding claims, characterised in that, in normal operation, the low temperature stage is passed through in the temperature range between 100 0 C and 600 0 C.

9. Method according to one of the preceding claims, characterised in that, in normal operation, the high temperature stage is passed through with the addition of oxygen.

10. Method according to the preceding claim, characterised in that, in normal operation, the carbon components in the charge are gasified by metered addition of oxygen into carbon dioxide so that the carbon dioxide when penetrating the carbon-containing charge is reduced into carbon monoxide.

11. Method according to one of the preceding claims, characterised in that, in normal operation, the high temperature stage is passed through at temperatures of more than 1000 0 C.

12. Device for material reprocessing, conversion and subsequent treatment of disposal materials of all types with a plurality of thermal treatment stages, which comprise at least one low temperature stage with oxygen exclusion and at least one high temperature stage with oxygen supply at temperatures above 1000 OC, and also with a stabilisation zone disposed in the high 12 temperature stage and with an outlet for the gas mixture produced in the high temperature stage, all reaction spaces of the treatment stages being connected to each other in a fixed manner without locks and, in the high temperature stage, devices for feeding oxygen and devices for feeding fuel being provided, characterised in that the gas outlet side of the high temperature stage is connected to a first rapid gas cooling and to a second rapid gas cooling following the first gas cooling in the gas flow, which have respectively a first or second water injection device for cold water into the hot flow of the gas mixture or of the waste gas.

13. Method according to the preceding claim, characterised in that the first and/or the second rapid gas cooling have a control device for controlling the quantity of cold water injected in the flow of the gas mixture or the flow strength of said water.

14. Device according to the preceding claim, characterised in that the quantity or flow strength of the injected cold water is controllable such that the synthesis gas in the first rapid cooling is shock cooled to approximately 150 0 C to 200 0 C and/or in the second rapid cooling to below 90*C.

15. Device according to one of the claims 12 to 14, characterised in that the first and/or second water injection device have a multiplicity of nozzles for injection of water into the first or second rapid cooling.

16. Device according to the preceding claim, characterised in that the nozzles can be switched off and on.

17. Device according to one of the claims 12 to 16, characterised in that a device for gas purification is disposed after the second rapid gas cooling.

18. Device according to the preceding claim, characterised in that the device for gas purification has a purification stage for removing H 2 S by means of iron chelate. 13

19. Device according to one of the claims 12 to 18 characterised in that, in the second rapid gas cooling, a device for gas utilisation for the synthesis gas mixture, for example a gas motor, a generator or the like, is disposed subsequently.

20. Device according to one of the claims 12 to 19, characterised in that the reaction space for the low temperature stage is a horizontally disposed, externally heated batch furnace having a rectangular cross-section, the ratio of oven width to oven height of which is greater than 2, the furnace length being given by the equation Lofen a 5 IFofen, with Fofen as the cross-sectional surface of the batch furnace.

21. Device according to one of the claims 12 to 20, characterised in that the reaction space for the high temperature stage is configured as a vertical shaft furnace into which the reaction space for the low temperature stage opens above its base.