AU770507B2 - Process and apparatus for the conversion of carbonaceous materials - Google Patents

Description

WO 00/56671 PCT/AU00/00206 Title "Process and Apparatus for the Conversion of Carbonaceous Materials" Field of the Invention The present invention relates to a process and apparatus for the conversion of carbonaceous materials. More particularly, the process and apparatus of the present invention provides an improvement to the oil product of the conversion of the organic components of sewage and industrial sludges.

Discussion of the Prior Art Sewage sludge is an unavoidable by-product of the treatment of sewage and other wastewaters. Traditionally, disposal of such sludge is expensive and typically constitutes half of the total annual costs of wastewater treatment.

Historically, the major sludge disposal options have included agricultural utilisation, landfilling and incineration. Also historically, wastewater treatment plants have been designed to minimise sludge production and most effort is expended to stabilise and reduce the sludge volume prior to disposal or utilisation.

The solids component of sewage sludge comprises a mixture of organic materials composed of mostly crude proteins, lipids and carbohydrates. These solids further comprise inorganic materials such as silt, grit, clay and lower levels of heavy metals. For example, a typical raw sewage sludge comprises approximately 50 to 90% volatile matter and 25 to 40% organic carbon. Some sewage sludges already exceed current land application contaminant standards and consequently cannot be used agriculturally or are classified hazardous waste, largely due to their organochlorine content.

Many sludge processing options have been proposed in the past. Such options have the potential to convert a fraction of the organic material into usable energy 1(1 I WO 00/56671 PCT/AU00/00206 -2and even less have been demonstrated as viable net energy producers at full scale. One common process involves anaerobic digestion of sewage sludge in which approximately 25% of available organic materials is converted to produce a gas rich in methane. Historically, other alternatives have included starved air incineration and gasification.

A significant problem associated with the above processes relates to the fact that the principle usable energy-containing products are gases which are generally not easily condensable and are of a low net energy content. Accordingly, such gases are impossible or uneconomic to store and must generally be used immediately.

Further, it is generally only practicable to use them to produce relatively low grade energy, such as steam, and flare them to waste during periods of little or no demand. Not surprisingly, it is preferable that any process used result in storable (liquid or solid), transportable and if possible, upgradable energy-containing products. Such products would include synthetic oils. It is consequently desirable that there be optimum production of storagable energy having any nonstorable products, used in the operation of the process itself.

Disposal of sewage sludge has become more problematic recently due to the fact that; a) agricultural use of sewage sludge is restricted by its contaminant content, particularly the organochlorine content, and within this group the dioxins have become the limiting factor, b) ocean disposal is banned, c) landfilling is to shortly be banned in the European Union; and d) incineration of sewage sludge is opposed by the public primarily with respect to the dioxin issue (reformation of dioxin during hot flue gas cooling). Consequently recent research work on thermal sludge disposal processes concentrates on control of organochlorine compounds across the process.

WO 00/56671 SPCT/AU00/00206 -3- In US Patents 4618735 and 4781796, there is described a process and apparatus for the conversion of sludges by heating and chemical reaction in order to obtain useful storable products therefrom, including oils. The process comprises the steps of heating dried sludge in a heating zone in the absence of oxygen to a temperature of at least 2500C for the volatilization of oil producing organic material therein, resulting in heating zone gaseous products and sludge residue, removing the said gaseous product from the heating zone; thereafter contacting heated sludge residue in a reaction zone with the removed heating zone gaseous products in the absence of oxygen at a temperature of 2800C to 6000C for repeated intimate gas/solid contact at temperatures sufficient to cause gas/solid contact, oil producing reactions to occur within the heating zone, gaseous products catalysed by the heated sludge residue resulting in reaction zone gaseous products containing oil products; removing the reaction zone gaseous products from the reaction zone and separating at least the condensable oil products therefrom.

Also disclosed is an apparatus for the conversion of sludge, said apparatus comprising an enclosure establishing a heated heating zone having an inlet thereto for dried sewage sludge and separate outlets therefrom for heating zone gaseous products and residual heating zone solid products; conveyor means within the heating zone enclosure for conveying solid products from its inlet to its solid products outlet; and enclosure establishing a heated reaction zone having separate inlets thereto for gaseous and solid products and separate outlets therefrom for gaseous and solid products; conveyor means within the reaction zone enclosure for conveying solid products from its solid products inlet to its solid products outlet; a heating zone solid products outlet being connected to the reaction zone solid products inlet for the passage of solid products between them; and duct means connecting the heating zone gaseous products outlet to the reaction zone gaseous products inlet.

WO 00/56671 PCT/AU00/00206 -4- In US Patents 5847248 and 5865956 there is disclosed a process and apparatus based on the process and apparatus of US Patents 4618735 and 4781796, with the following improvements.

The gaseous products from the heating zone are transferred to either an indirect or direct condenser with oil/water separation. The resulting oil and/or non-condensable products are injected into a second reactor. Sludge residue or char from the first reactor is transferred to the second reactor by way of a transfer line. The transfer line is equipped with a valve system to ensure that no gaseous products by-pass the condensation system.

In the second reactor, provided with heating means, the heated sludge residue from the first reactor is contacted with the revaporised oil or oil and non-condensable gaseous products from the condensation system in the absence of oxygen at a maximum temperature of 5500C. Such allows reductive, heterogenic, catalytic gas/solid phase reactions for the generation of clean products and high quality oil product. A conveyor and motor is provided to move the solid product or char through the second reactor.

Gaseous products are subsequently removed from the second reactor for passage through a further condenser and oil/water separation system or for ducting to a burner for direct combustion. In the case of passage through a further condenser and oil/water separation system a volume of non-condensable gaseous product, a volume of reaction water and a volume of refined, low viscosity oil is produced. Solid products or char are removed from the second reactor by way of a further transfer line having provided therein a screw conveyor for ensuring both no air ingress into and no gaseous product egress from the second reactor. The screw conveyor is connected to a cooling system to cool the solid product or char to less than 1000C before discharge to atmosphere.

The process and apparatus for the conversion of carbonaceous materials of the present invention has as one object thereof to provide a more simple and cost WO 00/56671 PCT/AU00/00206 effective process and apparatus still able to provide the various advantages of the process and apparatus of US Patents 5847248 and 5865956.

Disclosure of the Invention In accordance with the present invention there is provided a process for the conversion of sewage sludges, the process characterised by the steps of: feeding dried sludge through a reactor; heating the dried sludge in the reactor in the absence of oxygen for the volatilization of oil producing organic materials therein, resulting in gaseous products and sludge residue; transferring the gaseous products from the reactor to a catalytic converter; contacting the gaseous products from the reactor or the reheated oil and/or non-condensable products, if any, with a catalyst in the catalytic converter in the absence of oxygen; removing the gaseous products from the catalytic converter; and condensing and oil/water separating the gaseous products of the catalytic converter.

Preferably, sludge residue from the reactor is transferred to a storage bin through a valve system for ensuring both no air ingress into and no gaseous product egress from the reactor.

Still preferably, the feeding of the dried sludge through the reactor utilises a feed system that ensures both no air ingress into, and no escape of gaseous products from, the reactor.

The temperature of the reactor is preferably at least 2500C. The temperature of the reactor is still preferably about 4500C.

The process of the present invention may be further characterised by the method steps of: WO 00/56671 PCT/AU00/00206 -6transferring the gaseous products from the reactor to a condensation system to condense the oil product from the gaseous products; and reheating water free oil and/or non-condensable products, if any, from the condensation system in an oil reheater.

The condensation system of step preferably comprises a direct condenser.

The condensation of step preferably comprises indirect condensation at >1000C.

The direct transfer of gaseous products of step from the reactor to the catalytic converter preferably takes place in heat traced lines.

The temperature of the catalytic converter is preferably up to 6500C, thereby promoting reductive, catalytic gas/solid phase reactions and substantially eliminating hetero-atoms, including nitrogen, oxygen, sulphur, and halogens. The catalytic converter temperature is preferably in the range of 400 to 5500C. Still preferably, the catalytic converter temperature is in the range of 400 to 4200C.

The catalytic converter may contain a catalyst, the catalyst being chosen from any of zeolite, activated alumina, y-aluminium oxide, silicon oxide and oxides of alkali, earth alkali and transition metals. Preferably, the catalyst is zeolite.

The process of the present invention may be still further characterised by the step of testing the miscibility of the oil product with a hydrocarbon solvent, for example diesel fuel. In response, the catalytic converter conditions may be modified, thereby optimizing the catalytic conversion of sewage sludge, particularly the elimination of hetero-atoms such as halogens, nitrogen, oxygen and sulphur.

In accordance with the present invention there is further provided a process for the optimisation of the process for the conversion of sewage sludges as set out above with particular relevance to the removal of hetero-atoms to produce a PCT/AU00/00206 Received 5 February 2001 -7product miscible with a hydrocarbon solvent such as diesel fuel. Oils miscible in a hydrocarbon solvent have lower viscosity, water content and hetero-atom content, i.e. a higher oil quality. 'Consequently the miscibility with a hydrocarbon solvent can be used as an analytical tool to optimize the process.

The present invention still further provides a process for the conversion of sewage sludges, the process characterised by the steps of: feeding dried sludge through a first reactor; heating the dried sludge in the first reactor in the absence of oxygen for the volatilization of oil producing organic materials therein, resulting in gaseous products and sludge residue; transferring gaseous products from the first reactor to a first condensation system; transferring sludge residue to a second reactor where it is heated with oil and/or non-condensable products from the first condensation system; transferring the gaseous products of the second reactor to a catalytic converter; contacting the gaseous products of step with a catalyst in the catalytic converter in the absence of oxygen; removing the gaseous products from the catalytic converter; and condensing and oil/water separating the gaseous products of the catalytic converter.

Preferably, the temperature of both reactors is about 4500C. Still preferably, the catalytic converter has a temperature of about 400 to 4200C.

In accordance with the present invention there is still further provided an apparatus for the conversion of carbonaceous materials, the apparatus characterised by a feed system for dried material to be conveyed, a reactor, and a catalytic converter, the reactor having a solid product discharge outlet and a transfer line provided for transport of gaseous product directly or indirectly to the catalytic converter.

pMNDED ssET

IPUPJIAU

WO 00/56671 PCT/AU00/00206 -8- Preferably. a first condensation system is provided in-line between the reactor and catalytic converter. The first condensation system preferably includes an oil/water separation system.

The catalytic converter is preferably adapted to contact heated catalyst contained therein with oil or oil and non-condensable products of the condensation system, wherein gaseous products may be removed from the catalytic converter. A reheater may be provided between the first condensation system and the catalytic converter.

A second condensation system is prefarably provided to receive gaseous product from the catalytic converter.

Description of the Drawings The present invention will now be described, by way of example only, with reference to two embodiments thereof and the accompanying drawings, in which: Figure 1 is a schematic diagram of an apparatus for the conversion of carbonaceous materials in accordance with a first embodiment of the present invention; and Figure 2 is a schematic diagram of an apparatus for the conversion of carbonaceous materials in accordance with a second embodiment of the present invention.

Best Mode(s) for Carrying Out the Invention In Figure 1 there is shown an apparatus 10 for the conversion of sludges in accordance with a first embodiment of the present invention. The apparatus comprises a feed system 12 for dried sludge 14. The feed system 12 feeding said sludge 14 to a reactor 16. The feed system 12 is such that it ensures both no air ingress and no gaseous egress from the reactor 16.

WO 00/56671 PCT/AU00/00206 -9- The reactor 16 is provided with heating means 18 thereabout, such that dried sludge may be heated therein in the absence of oxygen to at least 2500C. This results in the volatilization of oil producing organic materials in the reactor 16.

Further, this reaction provides gaseous products and sludge residue or char. A screw conveyor 20 and a motor 22, or their equivalent, is provided to move the sludge through the reactor 16.

The gaseous products from the reactor 16 are either transferred to a combustion system 24, to a catalytic converter 26 or to a first condensation system 28 with oil/water separation. Further, the first condensation system 28 may comprise either a direct or an indirect condenser. The resulting oil is injected, via line with or without any non-condensable products, via line 32, from the first condensation system 28 into an oil reheater 34 where the oil and/or noncondensable products 32 are heated in the absence of oxygen to a maximum temperature of 6500C.

The gaseous products from the reactor 16 or the preheated oil and/or noncondensable products from the oil reheater 34 are injected into the catalytic converter 26, via lines 31 and 33 respectively. Line 31 from the reactor 16 to the catalytic converter 26 is heat traced. The catalytic converter 26 is provided with a heating means 36 thereabout such that the preheated oil and/or non-condensable products may be heated therein in the absence of oxygen to a maximum temperature of 6500C. This allows reductive, catalytic removal of hetero-atoms to produce an oil product of a viscosity that is lower than that of diesel. The refined gaseous products from the catalytic converter 26 are transferred, via line 37, to a final or second condensation system 38 with oil/water separation.

The solid product or char of the reactor 16 is removed from the reactor 16 by way of a transfer line 40. The transfer line 40 is equipped with a valve system 42 and a screw conveyer (not shown). The valve system 42 is such that it ensures both no air ingress and no gaseous egress from the reactor 16. The screw conveyer is WO 00/56671 PCT/AU00/00206 connected to a cooling system 44 to cool the solid products or char to less than 100C.

In Figure 2 there is shown an apparatus 100 for the conversion of sludges in accordance with a second embodiment of the present invention. The apparatus 100 is substantially similar to the apparatus 10 and like numerals denote like parts.

A second reactor 102 is provided to receive the solid product or char of the "first" reactor 16 by way of transfer line 40 and the fluid tight valve system 42. The second reactor 102 is provided with heating means 104 thereabout.

Revaporised oil or oil and non-condensable gaseous products from the condensation system 28 are contacted with the char in the second reactor 102 and are heated in the absence of oxygen at a maximum temperature of 5500C. A screw conveyor 106 and motor 108, or their equivalent, are provided to move the solid product or char through the second reactor 102.

The solid products or char are removed from the second reactor 102 by way of a further transfer line 110 having provided therein a screw conveyor 112 for ensuring both no air ingress into and no gaseous product egress from the second reactor 102. The screw conveyor 112 is connected to a cooling system 114 to cool the solid product or char to <100C before discharge to atmosphere.

Gaseous products of the second reactor 102 are removed for injection to the catalytic converter 26 via line 33.

The present invention may be further described with reference to the following example.

WO 00/56671 PCT/AU00/00206 -11 Example The sewage sludge employed in the determination of process data using the continuous apparatus of the present invention was raw sludge from two locations, being the Subiaco Waste Water Treatment Plant (WWTP), Perth, Western Australia, and the Atlanta WWTP, Georgia, United States of America. The sludges were dried to approximately 95% dryness in a drying oven at 70°C prior to processing.

The sludges were processed in either the apparatus 10 or the apparatus 100 as described hereinabove.

The first series of tests were conducted to demonstrate the impact of the catalytic converter on oil quality. Results are shown in Table 1.

Table 1 Oil Quality Data: Impact of Catalytic Conversion Run No. Run 1 Run 2 Run 3 Run 4 Parameter Viscosity 400C [cSt] 25.8 29.8 3.2 7.7 Water Content 9.4 6.7 0.72 2.2 Run 1: Subiaco sludge was processed as described in US patent 5847248.

As such, gaseous products are condensed after the first reactor and the oil product is injected into the second reactor. Both reactors were operated at 4500C, with the feedrate being 600g/hr. No catalyst was used.

Run 2: Conversion of raw sludge from the Atlanta WWTP, otherwise as per Run 1.

WO 00/56671 PCT/AUOO/00206 -12- Run 3: Subiaco sludge processed in accordance with the second embodiment of the present invention with gaseous products being condensed and the oil product, after passing through the reheater prior to the second reactor before being contacted with the catalyst (aluminium oxide impregnated with transition metal oxides) in the catalytic converter.

The catalytic converter temperature was maintained at 4000C.

Run 4: As per Run 3 but using Atlanta sludge, with gaseous products being directly transferred to the catalytic converter.

The above results clearly show that the oil viscosity and water content are reduced significantly by the use of the catalytic converter, for example compare Runs 1 and 3, and 2 and A second series of tests was conducted to determine the influence of catalyst support. Test results are shown in Table 2.

Table 2: Oil Quality versus Catalyst Support unNo. Run6 Run7 Run8 Run9 Run10 Run11 Parameter Viscosity 400C [cSt] 20.9 21.4 7.8 4.7 4.8 27.8 Water Content 1.1 4.4 1.7 1.5 -4.6 Run 6: Atlanta sludge was processed in accordance with the second embodiment of the present invention, with gaseous products being condensed and the oil product being preheated prior to injection into the second reactor from where it is transferred to the catalytic converter. The temperature of both reactors and catalytic converter WO 00/56671 PCT/AU00/00206 -13was controlled at 4500C. Sludge feed rate was controlled at 600 g/hr.

Pure AI 2 0 was used as a catalyst and was activated at 6000C.

Run 7: As per Run 6, with A 2 0 3 being activated at 12000C as a catalyst.

Run 8: As per Run 6, with AI 2 0 3 being impregnated with transition metal oxides and catalytic converter temperature being 4000C.

Run 9: As per Run 6, using silica gel as catalyst.

Run 10: As per Run 6, processing Subiaco sludge and using zeolite as catalyst with catalytic converter temperature being 4200C.

Run 11: As per Run 6, using char as catalyst.

The results show that pure A1 2 0 3 is not as good as A1 2 0 3 doped with transition metals. Silica gel and zeolite appear to be good catalysts and the conversion char is not as good as A1 2 0 3 as a catalyst.

A third series of tests were conducted to assess the impact of catalyst temperature on oil quality and yield. Results are shown in Table 3.

Table 3: Oil Quality and Yield versus Catalyst Temperature WO 00/56671 PCT/AUOO/00206 -14- Run 12: Subiaco sludge was processed in accordance with the first embodiment of the present invention, with gaseous products being condensed and the oil product being preheated prior to injection into the catalytic converter. The temperature of reactor and catalytic converter was controlled at 450 and 4000°C respectively. Sludge feed rate was controlled at 600 g/hr. Zeolite was used as a catalyst.

Run 13: As per Run 12, with catalyst temperature being 4200C.

Run 14: As per Run 12, with gaseous products being directly transferred to the catalyst and a catalyst temperature of 4500C.

Run 15: As per Run 14, with catalyst temperature being 4700C.

Run 16: As per Run 14, with catalyst temperature being 5000C.

Run 17: As per Run 14, with catalyst temperature being 5200C.

Run 18: As per Run 14, with catalyst temperature being 5300C.

Run 19: As per Run 14, with catalyst temperature being 5400C.

Run 20: As per Run 14, with catalyst temperature being 5500C.

The above results indicate that the optimal temperature for oil quality, when using a zeolite catalyst is 400 to 4200°C, with intermediate condensing, and 530-5500°C without intermediate condensing. There does appear to be a drop in oil yield when using the zeolite catalyst up to 5500C.

A fourth series of tests were conducted to asses the impact of catalyst to oil vapor ratio on oil quality. Results are shown in Table 4.

WO 00/56671 PCT/AUOO/00206 Table 4: Catalyst to oil vapour ratio versus oil Quality and Quantity Run No. Run 21 Run 22 Run 23 Parameter Weight Hourly Space Velocity (WHSV) 2.3 1.1 0.7 Viscosity 400°C [cSt] 13 4.5 4.8 Water Content 3.6 1.2 1.1 Oil Yield 23.2 18.8 18.3 Run 21: Atlanta sludge was processed in accordance with the second embodiment of the present invention, with gaseous products being condensed and the oil product being preheated prior to injection into the second reactor from where it is transferred to the catalytic converter. The temperature of both reactors and the catalytic converter were controlled at 4500°C. Sludge feed rate was controlled at 600 g/hr.

Aluminium oxide impregnated with transition metal oxides was used as a catalyst and 80 g of catalyst used.

Run 22: As per Run 21, with 165 g of catalyst being used.

Run 23: As per Run 21, with 265 g of catalyst being used.

As expected, the results show improved oil quality at lower WHSV (higher catalyst mass), albeit at a reduced oil yield. There does not appear to be any further improvement in oil quality by reducing the WHSV to below 1 hr 1 A fifth series of tests was conducted to assess the impact of catalyst regeneration on oil quality. Results are shown in Table WO 00/56671 PCT/AU00/00206 -16- Table 5: Catalyst Regeneration versus Oil Quality Run24: Subiaco sludge was processed in accordance with the first embodiment of the present invention, with gaseous products being transferred directly to the catalytic converter. The temperature of the reactor and the catalytic converter was controlled at 450 and 5500C respectively. Sludge feed rate was controlled at 600 g/hr. 210 g of native zeolite was used as a catalyst.

Run 25: As per Run 24, with the catalyst being regenerated on-line for the first time.

Run 26: As per Run 24, with the catalyst being regenerated on-line for the second time.

Run 27: As per Run 24,. with the catalyst being regenerated on-line for the third time.

Run 28: As per Run 24, with the catalyst being regenerated on-line for the fourth time.

Run 29: As per Run 24, with the catalyst being regenerated on-line for the fifth time.

WO 00/56671 PCT/AU00/00206 -17- The results show a slight deterioration in catalyst efficacy via on-line regeneration. However, performance appeared to stabilise after 3 or 4 regenerations.

A sixth series of tests were conducted to compare oil yield and quality from the dual reactor system with intermediate condensation and the single reactor system without intermediate condensation. The results are shown in Table 6.

Table 6: Oil Quality Data: Impact of Dual versus Single Reactor Systems Run No. Run 30 Run 31 Parameter Oil Yield 18.8 16.9 Viscosity [cSt] 4.5 7.6 Run 30 Atlanta WWTP sludge was processed in accordance with the second embodiment of the present invention, with gaseous products being condensed after the first reactor and the oil product was injected into the second reactor. The temperature of both the reactor and the catalytic converter was controlled at 4500C. Sludge feed rate was controlled at 600 g/hr. A1 2 0 3 was used as the catalyst.

Run 31: As per Run 30 but rather in accordance with the first embodiment of the present invention, that is without the intermediate condensing of gaseous products or the second reactor.

These results indicate that the presence of the second reactor, and the condensation of gaseous products before injection thereto, does not have a WO 00/56671 PCT/AU00/00206 -18significant impact upon oil yield and quality, as might otherwise have been expected, when compared with the apparatus 10 utilising the single reactor 16.

A seventh series of tests were conducted to determine the impact of intermediate condensation on oil quality and yield in the single reactor system. Test results are shown in Table 7.

Table 7: Oil Data: Impact of Intermediate Condensing Run No. Runs 13/32 Run 14 Parameter Oil Viscosity [cst] 8.9 31.7 Oil Yield 17.9/23.3 25.1 Runs 13/32: Subiaco sludge was processed in accordance with the first embodiment of the present invention, with gaseous products being condensed and the oil reheated before being injected to the -catalytic converter. The temperature of the reactor was maintained at 450C and the converter at 4200C. The catalyst was zeolite.

Run 14: As per Run 13/32 with gaseous products being transferred directly to the catalytic converter which as operated at 4500C.

These results indicated that the intermediate condenser has a significant impact on oil quality. There is however, a significant oil yield penalty when using the intermediate condenser.

An eighth series of tests was conducted to determine the temperature at which the catalytic converter must be operated to achieve acceptable results in a single WO 00/56671 PCT/AUOO/00206 -19reactor system, without intermediate condensation. Test results are shown in Table 8.

Table 8: Oil Quality Data: Impact of Catalytic Converter Temperature Run No. Run 32 Run 33 Parameter Weight of Catalyst 180 210 Catalyst Temperature 420 550 Oil Yield 23.3 15.7 Viscosity [cSt] 8.9 11.8 Run 32 Subiaco sludge was processed in accordance with the first embodiment of the present invention, with gaseous products being condensed after the single reactor prior to injection to the catalytic converter. The temperature of the reactor and the catalytic converter was controlled at 4500C and 4200C. Sludge feed rate was controlled at 600 g/hr. Zeolite was used as the catalyst.

Run 33: As per Run 32 but without the condensing of gaseous products prior to introduction to the catalytic converter, which was operated at 5500C.

These results indicate that the condensing of the gaseous products of the single reactor prior to injection to the catalytic converter provides an improved oil quality and yield when compared with not having conducted the condensation step, when using zeolite as the catalyst.

WO 00/56671 PCT/AUOO/00206 These results further indicate that the catalytic converter must be operated at about 1300C higher if it is desired to produce oil of the same quality without intermediate condensation of the gaseous products of the reactor. As seen in Table 8, this produces a significant drop in oil yield.

The process for the conversion of sewage sludges of the present invention may be optimised with regard to removal of hetero-atoms through use of miscibility with a standard hydrocarbon source such as diesel fuel. It is apparent that the miscibility with diesel fuel is significantly influenced by the presence of hetero-atoms such as oxygen, nitrogen and sulphur. Such hetero-atoms particularly oxygen and sulphur and to a lesser degree nitrogen are removed by the catalytic converter generating an oil that is miscible at any ratio with diesel fuel. Accordingly, the miscibility of the oil product is a direct measurement of the quality of the oil. The miscibility can be directly correlated with viscosity, meaning the better mixing the lower the viscosity. As stated in US Patent 5847248, viscosity can also be used as an indicator for the destruction rate of organochlorine compounds and consequently, since the heavy metal oxides present in the catalytic converter are the same as in sewage sludge, the dehalogenation of organochlorines will take place in the catalytic converter at a much higher rate than in the second reactor of US Patents 5847248 and 5865956, and miscibility can also be used as a control tool for organochlorine destruction.

The process and apparatus of the present invention provide reductive, thermal heterogenic catalytic solid/gas phase reactions in order to obtain storable products with unrestricted use.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

Claims (23)

1. A process for the conversion of sewage sludges, the process characterised by the steps of: feeding dried sludge through a reactor; heating the dried sludge in the reactor in the absence of oxygen for the volatilization of oil producing organic materials therein, resulting in gaseous products and sludge residue; transferring the gaseous products from the reactor to a catalytic converter; contacting the gaseous products from the reactor or the reheated oil and/or non-condensable products, if any, with a catalyst in the catalytic converter in the absence of oxygen; removing the gaseous products from the catalytic converter; and condensing and oil/water separating the gaseous products of the catalytic converter.

2. A process according to claim 1, wherein sludge residue from the reactor is transferred to a storage bin through a valve system for ensuring both no air ingress into and no gaseous product egress from the reactor.

3. A process according to claim 1 or 2, wherein the feeding of the dried sludge through the reactor utilises a feed system that ensures both no air ingress into, and no escape of gaseous products from, the reactor.

4. A process according to claim 2 or 3, wherein the temperature of the reactor is at least 2500C. A process according to claim 4, wherein the temperature of the reactor is about 4500C. WO 00/56671 PCT/AU00/00206 -22-

6. A process according to any one of the preceding claims, the process further characterised by the method steps of: transferring the gaseous products from the reactor to a condensation system to condense the oil product from the gaseous products; and reheating water free oil and/or non-condensable products, if any, from the condensation system in an oil reheater.

7. A process according to any one of the preceding claims, wherein the condensation system of step comprises a direct condenser.

8. A process according to claim 6, wherein the condensation of step (g) comprises indirect condensation at >100C.

9. A process according to any one of the preceding claims, wherein the direct transfer of gaseous products of step from the reactor to the catalytic converter takes place in heat traced lines.

10.A process according to any one of the preceding claims, wherein the temperature of the catalytic converter is up to 6500C, thereby promoting reductive, catalytic gas/solid phase reactions and substantially eliminating hetero-atoms, including nitrogen, oxygen, sulphur, and halogens.

11.A process according to claim 10, wherein the catalytic converter temperature is in the range of 400 to 5500C.

12.A process according to claim 10, wherein the catalytic converter temperature is in the range of 400 to 4200C.

13.A process according to any one of the preceding claims, wherein the catalytic converter contains a catalyst, the catalyst being chosen from any PCT/AU00/00206 Received 5 February 2001 -23- of zeolite, activated alumina, y-aluminium oxide, silicon oxide and oxides of alkali, earth alkali and transition metals.

14.A process according to claim 13, wherein the catalyst is zeolite. process according to any one of claims 6 to 14, wherein the process further comprises the step of testing the miscibility of the oil product with a hydrocarbon solvent and modifying the conditions of the catalytic converter in response thereto.

16.A process according to any one of claims 6 to 15, wherein the oil product of the process is miscible with a hydrocarbon solvent.

17.A process according to claim 16, wherein the solvent is diesel fuel.

18.A process for the conversion of sewage sludges, the process characterised by the steps of: feeding dried sludge through a first reactor; heating the dried sludge in the first reactor in the absence of oxygen for the volatilization of oil producing organic materials therein, resulting in gaseous products and sludge residue; transferring gaseous products from the first reactor to a first condensation system; transferring sludge residue to a second reactor where it is heated with oil and/or non-condensable products from the first condensation system; transferring the gaseous products of the second reactor to a catalytic converter; contacting the gaseous products of step with a catalyst in the catalytic converter in the absence of oxygen; removing the gaseous products from the catalytic converter; and condensing and oil/water separating the gaseous products of the catalytic converter. AMIENDED SHEET IPMNAU WO 00/56671 PCT/AU00/00206 -24-

19.A process according to claim 18, wherein the temperature of both reactors is about 4500C. process according to claim 18, wherein the catalytic converter has a temperature of about 400 to 4200C. 21 .An apparatus for the conversion of carbonaceous materials, the apparatus characterised by a feed system for dried material to be conveyed, a reactor, and a catalytic converter, the reactor having a solid product discharge outlet and a transfer line provided for transport of gaseous product directly or indirectly to the catalytic converter.

22.An Apparatus according to claim 21, wherein a first condensation system is provided in-line between the reactor and catalytic converter.

23.Apparatus according to claim 22, wherein the first condensation system includes an oil/water separation system.

24.Apparatus according to any one of claims 21 to 23, wherein the catalytic converter is adapted to contact heated catalyst contained therein with oil or oil and non-condensable products of the condensation system, wherein gaseous products may be removed from the catalytic converter. according to any one of claims 21 to 24, wherein a reheater is provided between the first condensation system and the catalytic converter.

26.Apparatus according to any one of claims 19 to 25, wherein a second condensation system is provided to receive gaseous product from the catalytic converter.

27.A process for the conversion of sewage sludges substantially as hereinbefore described with reference to Figure 1 or 2. WO 00/56671 PCT/AUOO/00206

28.Apparatus for the conversion of sewage sludges substantially as hereinbefore described with reference to Figure 1 or 2.