GB2499329A

GB2499329A - Thermal energy plant for utilising waste from the tanning process

Info

Publication number: GB2499329A
Application number: GB1303399.8A
Authority: GB
Inventors: Warren Brian Bowden
Original assignee: SLG TECHNOLOGY Ltd
Current assignee: SLG TECHNOLOGY Ltd
Priority date: 2013-02-26
Filing date: 2013-02-26
Publication date: 2013-08-14
Anticipated expiration: 2033-02-26
Also published as: GB2499329B; GB201303399D0

Abstract

The present invention relates to methods or processes for utilising the waste streams from leather processing to produce energy by pyrolysing or gasifying the waste. It also relates to a system, in the form of a thermal energy plant which converts a portion of tannery waste to heat energy. In a preferred embodiment, the invention relates to a cyclical process whereby a portion of the waste effluent from leather manufacturing is converted to energy which can then be used in the leather making process. The thermal energy plant is closely associated with, and located near to, leather processing plants. This reduces the amount of carbon fuel required in the leather manufacturing process resulting in the production of leather which has used less carbon/fossil fuel in its manufacture than is used currently in leather production.Figure 4

Description

1

A thermal energy plant for and process of utilising waste from the tanning process

The present invention relates to methods or processes for utilising the waste 5 streams from leather processing to produce energy. It also relates to a system, in the form of a thermal energy plant which converts waste to heat energy. Most preferably the invention relates to a cyclical process whereby the waste from leather manufacturing is converted to energy which can then be used in the leather making process. The thermal energy plant is closely associated with and located 10 near to leather processing plants. This reduces the amount of carbon fuel required in the leather manufacturing process resulting in the production of leather which has used less carbon in its manufacture.

The tanning process

15

Hides and skins of animals, primarily cattle, are the source of leather. Leather production methods have been known for many years and it is generally accepted that there is a high environmental impact from leather production. In particular, the production process results in significant amounts of waste products, much of which 20 contain contaminants and are thus difficult to dispose of safely, and there are high energy consumption requirements for the processing of hides to leather.

Generally, in order to manufacture leather, hides are removed from animal carcasses using known techniques and "fleshed" to remove any remaining fat and 25 organic tissue. The fleshed hides are then sent for processing into leather whilst the removed fleshings (in the form of fat containing organic matter] are a waste product. Solid wastes can represent greater than 70% of the original wet weight hides.

30 The fleshed hides are tanned, most commonly via chrome tanning where the hides are bathed in an appropriate chemical mix and then fixed. The chemical fixing process also results in a significant amount of waste effluent, often containing

2

contaminants such as chromium and sulphide. Further processing of the tanned leather can then occur to give a finished leather product appropriate for the desired end use and also produces further solid waste in the form of trimmings, shavings and buffing dust.. The entire tanning process requires significant use of fossil or 5 carbon based fuels.

Treatment of waste

Various treatment processes have been put in place to try to safely remove waste 10 from the tanning process, and there are legal and social pressures for tanneries to try to reduce the environmental impact of their processes. Figure 1 shows a wastewater treatment plant of the type that can be found in UK tanneries. It is appreciated by those skilled in the art that variations can be made dependent on the requirement of the tannery to which the effluent treatment plant is linked. 15 Wastewater treatment is a multistage process and aims to remove contaminants from the waste effluent to allow at least some of it to be disposed of through normal sewerage routes whilst the main pollutants and converted into a more manageable waste product such as sludge.

20 Initially the incoming effluent is segregated into alkaline and acidic streams (liming and tanning streams], which is essential for safety and to avoid the formation of potentially dangerous hydrogen sulphide. Pre-treatment of the streams using conventional methods is carried out separately to avoid said safety issues, before the pre-treated streams are then combined. Primary treatment then occurs in a 25 dissolved air flotation (DAF] system where sedimentation can occur, with sludge settling at the bottom and being removed, and floatable materials being removed from the top for further treatment. The sludge and slurry that results is dewatered, in Figure 1 this is via a bank of centrifuges although it is appreciated that other dewatering options are available, before further filtration and purification of the 30 liquid stream is carried out. The resultant sludge/solids from the dewatering stage is usually then disposed of, in many cases into landfill, whilst the decontaminated

3

liquid stream can either be disposed into usual sewerage routes or further processed if required.

It is appreciated that it would be useful to minimise the amount of waste that goes 5 to landfill. Further, it is appreciated that the current tanning process requires significant amounts of fuel consumption resulting in high carbon use. The present invention aims to obviate or mitigate some of the concerns associated with current tanning processes.

10 Reference to "tannery processing waste" is taken to be "sludge waste" or "sludge effluent" that is obtained from the treatment of tannery effluent through a wastewater treatment plant of the type referenced above, unless otherwise indicated and/or also the solid waste from the further processing of the tanned hides which is typically in the form of trimming, shavings and buffing dust..

15

According to a first aspect of the present invention there is provided a method of utilising tannery processing waste obtained from the treatment of tannery waste effluent, comprising the steps of;

drying said tannery processing waste;

20 milling said dried tannery processing waste to produce particulate matter;

pyrolising and gasifying said particulate waste to obtain syngas; and oxidising said syngas to produce heat.

Optionally the tannery processing waste is sludge waste obtained from the 25 treatment of tannery effluent.

Optionally the tannery processing waste is solid waste from the further processing of the tanned hides in the form of trimmings and/or shavings and/or buffing dust.

30 Optionally the tannery processing waste is a combination of sludge waste and trimmings and/or shavings and/or buffing dust

4

Preferably the heat is used to produce steam.

Preferably the heat energy is utilised by the tannery.

5 Optionally the heat energy is utilised in the tannery hot water system.

Optionally the heat energy is used to produce steam which powers machinery used in the tanning process.

10 The heat energy can be used to generate electricity.

Syngas (synthetic gas] cannot easily be stored and therefore it is most effective to oxidise or burn the gas as soon as possible in order to produce heat. Using the heat energy in the tanning process reduces the amount of additional fossil fuel that needs 15 to be brought in to the tanning process resulting in a cyclical process with reduced carbon requirements. Effectively the waste stream which previously would be disposed in land fill now can be used as a fuel for the tanning process. Importantly, the more tanning that is being carried out, the more waste that is produced, which ensures that the energy which can now be obtained from the waste stream 20 increases with the amount of waste being produced.

Preferably the drying of said tannery processing waste takes place in a flash drier.

Preferably the milling of said dried waste takes place in an attrition mill.

25

Most preferably the drying and milling of the tannery processing waste takes place in an attrition mill flash drier.

Preferably the particulate matter has a particle size of less than 1mm.

30

Preferably the particulate matter has a density of less that 0.4kg/m3.

5

Preferably the particulate matter has a particulate size and density that is sufficient to allow predominantly all of the particulate matter to undergo flaming pyrolysis rather than incineration when exposed to appropriate temperatures (for example temperatures greater than 400°C].

5

Preferably the particulate matter is cyclonically separated.

Preferably the temperature of particles in the particulate matter does not exceed 70°C during milling and/or separation.

10

Preferably the attrition mill flash drier (an example of which is a Scott drier] flash dries the tannery processing waste. This is important for leather waste as waste from a tannery will effectively melt if held at too high a temperature for any significant period of time. It is therefore very beneficial that there is rapid airflow 15 through the drier to stop the waste from melting and sticking. It is preferred that he temperature of the particulate is kept lower than 70°C although the air temperature can be significantly higher to ensure rapid drying.

If the density of the particulate is too high then the particulate will not undergo 20 flaming pyrolysis in the gasifier (it will tend to incinerate rather than pyrolise if the particule size or density of the particulate matter is too large].

Preferably the pyrolysis and gasification step occurs at temperatures of greater than approximately 400°C.

25

Most preferably the pyrolysis and gasification step occurs at temperatures of approximately 800°C.

Pyrolysis is an endothermic reaction that, in this case, results in the production of 30 synthetic gas or syngas.

Preferably pyrolysis occurs in a gasifier.

6

Optionally the layer of particulate matter in the gasifier does not exceed 0.5 meters in depth.

5 More preferably, the layer of particulate matter in the gasifier does not exceed 0.3 meters (300mm] in depth.

Preferably any remaining particulates are removed from the syngas. 10 Optionally particulates are removed using a cyclone.

Preferably the heat energy is then cyclically used in said tanning process.

Optionally the gas stream from the oxidation of the syngas is cleaned.

15

According to a second aspect of the present invention there is provided a method of using of utilising tannery processing waste , comprising the steps obtaining tannery processing waste from the tanning process;

processing tannery processing waste ;

20 Utilising said tannery processing waste in the method of the first aspect.

As indicate above the method of the first step generally requiresnamely, drying said tannery processing waste;

milling said dried tannery processing waste to produce particulate matter; 25 pyrolising and gasifying said particulate matter to obtain syngas; and oxidising said syngas to produce heat.

Most preferably the tannery processing waste is kept separate from any fleshings waste.

30

As fleshings cannot be dried, the effluent is treated as a separate waste stream.

7

According to a third aspect of the present invention, there is provided a system for utilising tannery processing waste comprising;

a drier which is adapted to receive said tannery processing waste;

a mill which is adapted to break down the dried tannery processing waste into 5 particulate matter;

a gasifier, positioned downstream from the mill, said gasifier being adapted to receive the particulate matter and flamingly pyrolise said particulate matter to produce syngas;

a thermal oxidiser, positioned downstream from the gasifier, said oxidiser adapted 10 to receive and burn the syngas to produce heat.

Preferably the system is a thermal energy plant.

Preferably the thermal energy plant is in close proximity or is part of a leather 15 processing plant.

Preferably the mill breaks down the dried waste into particulate matter with a particle size of less than 1mm.

20 Preferably the mill breaks down the dried waste into particulate matter with a density of less that 0.4kg/m3.

Preferably the mill grinds the dried waste into a particulate matter which has a particulate size and density that is sufficient to allow predominantly all of the 25 particulate matter to undergo flaming pyrolysis rather than incineration when exposed to appropriate temperatures (for example temperatures greater than 400°C, preferably approximately 800°C}.

If the density of the particulate is too high then the particulate will not undergo 30 flaming pyrolysis in the gasifier.

Optionally the drier and mill are combined.

8

Optionally the combined drier and mill is an attrition mill flash drier.

Preferably the gasifier has an internal temperature of greater than 400°C.

5

Preferably the gasifier has an internal temperature of approximately 800°C.

Preferably the base gasifier is substantially planar and flat.

10 Preferably an eductor system is used to draw the syngas from the gasifier into the thermal oxidiser.

The educator system utilises the venturi effect and comprises a motive inlet upstream of the thermal oxidiser and downstream of the gasifier. Steam enters via 15 the motive inlet. The ID fan does not draw from the gasifier, only from the thermal oxidiser, resulting in syngas being drawn into the thermal oxidiser.

Preferably an eductor system is part of an inert system.

20 As syngas is highly flammable it is understood that it should be in an inert/sealed system to prevent ignition of the gas.

Preferably the thermal oxidiser converts the syngas to heat.

25 Optionally the heat is used to produce steam.

Optionally the gas stream exiting the thermal oxidiser is cleaned.

According to a fourth aspect of the present invention there is provided a thermal 30 energy plant for utilising waste sludge from the tanning process, comprising the system of the third aspect.

9

As indicated above the system of the third aspect is generally;

a dryer which receives tannery processing waste;

a mill which is adapted to break down the dried tannery processing waste into particulate matter;

5 a gasifier, positioned downstream from the mill, said gasifier being adapted to receive the particulate matter and flamingly pyrolise said particulate matter to produce syngas;

a thermal oxidiser, positioned downstream from the gasifier, said oxidiser adapted to receive and burn the syngas to produce heat.

10

Most preferably the thermal energy plant is in close proximity to, or is directly connect with, one or more leather processing plants.

In order to ensure the carbon usage of the tanning process is kept low it is 15 understood that a holistic approach is preferred with distances between the thermal energy plant and other tanning processing or leather processing plants being kept to a minimum. This reduces unnecessary transportation of waste which would of course have its own carbon draw.

20 The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention.

In order to provide a better understanding of the present invention, embodiments will now be described with reference to the following figures in which;

25

Figure 1 shows a system diagram of an waste water treatment plant/ effluent plant which takes the effluent from the tanning process and removes impurities to allow much of the liquid to be disposed of through standard sewerage routes and resulting in a waste sludge that can be converted to heat using the process of the present 30 invention; and

10

Figure 2 shows a diagram of a conventional gasifier; and

Figure 3 shows a diagram of an improved gasifier that can be used in a preferred embodiment of the present invention; and

5

Figure 4 shows a system diagram indicating how the thermal energy plant can be integrated with tannery systems.

Throughout the description and claims of this specification, the words "comprise" 10 and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not] exclude other components, integers or steps.

Throughout the description and claims of this specification, the singular 15 encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers or characteristics, compounds described in conjunction with a 20 particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. In particular it will be understood that where the description is referencing sludge waste or sludge effluent from the treatment of wastewater, this could also refer to waste from the further processing of tanned 25 hides which results in trimmings, shavings and buffing dust, or could further relate to combinations of sludge effluent, trimming, shavings and buffing dust. It would however also be understood that it does not apply to fleshings waste which cannot be dried and must be dealt with separately. Thus where reference is made to tannery processing waste this excludes fleshings.

30

In accordance with a first aspect of the present invention there is provided a method of utilising tannery processing waste obtained from the treatment of tannery waste

11

effluent to provide heat. This aspect also describes the system which includes the relevant physical structures which allows for the method to be carried out. The physical aspects of the system are in the form of a thermal energy plant. As mentioned previously, it will be appreciated that even though this example 5 describes sludge waste or sludge effluent, it could apply to tannery processing waste from further processing of tanned leather or combinations of both this and the sludge waste/sludge effluent. As previously indicated, the tanning process produces significant amounts of waste. It is known to treat waste effluent to, where possible, remove contaminants such that much of the waste effluent can then be disposed of 10 through usual sewerage routes. Figure 1 shows a known type of effluent treatment plant 1 where effluent enters as two streams from liming and tanning, which are alkaline (high S2} and acidic. In order to avoid safety problems the alkaline stream is pre-treated (sulphide oxidation] before being combined with acidic stream. The effluent is then fed into a first dissolved air flotation (DAF] system 2 which acts to 15 separate certain components by floatation. Generally, sludge is skimmed off the top and effluent is removed from the bottom. The effluent is further treated, often by biological treatment, with any remaining sludge being passed into a centrifuge 3. The settled sludge from the DAF 2 is also passed to a centrifuge 3 for dewatering. The liquid element from the centrifuge 3 can then be passed back through the 20 process whilst the remaining sludge effluent 4 or sludge waste is removed. In prior art techniques the sludge effluent is commonly disposed of by landfill, potentially after being placed in drying beds (not shown in fig 1}.

In the present invention the tannery effluent, which in this example is sludge (but 25 which could be, or could further include, waste from the processing of tanned hides) is not sent to landfill, but is instead used in a process to create heat energy in a thermal energy plant 5. Sludge effluent enters through a sludge feed 6 (which could be termed a tannery effluent feed if the waste is a type of tannery effluent other than sludge] and travels along an apron belt feeder 7 into a hopper 8. The sludge is the 30 fed into a dryer 9. Air may be fed into the dryer 9 from a hot air well 10. Preferably the dryer 9 is an attrition mill flash dryer which both dries the sludge and mills it. This step is effectively preparing the sludge into a fuel form that will undergo

12

flaming pyrolysis gasification without incineration (or with minimal incineration}. The sludge effluent is then in the form of dried particulate matter.

It is preferable that the sludge is ground into particulate matter where the particle 5 size is approximately 1mm and the density of the particulate matter is 0.4kg/m3. It is important that the particulate mater has an appropriate particle size and density. The particulate should be small enough that it will undergo pyrolysis at an appropriate temperature rather than be incinerated. If the particle size is too large and/or the density of the particulate matter is too high flaming pyrolysis and 10 gasification will not occur or will be partial.

The particulate matter is cyclonically separated. This may be in a separate cyclone separator 11 or as part of the attrition mill flash dryer (an example of which is a Scott dryer}.

15

It will be appreciated by those skilled in the art that any appropriate means from drying the sludge and grinding or milling it to ensure it is in particulate form could be used. However, the use of a flash dryer with a low retention time has been found by the inventor to be particularly beneficial when handling waste effluent from 20 leather making and tanning processes. Leather/tanning waste will effectively melt if it is held a too high a temperature for too long a time. A high speed of airflow through is required to stop the particulate matter or sludge waste from "sticking". It is preferable that the temperature of the particulate should not be greater than 70°C, although the surrounding air temperature can, and generally should, be 25 significantly higher and can be as much as 400°C.

The dried particulate matter is then fed into a gasifier 12, which also acts as a flaming pyrolyser. Conventional gasifiers which use flaming pyrolysis to produce syngas (synthetic gas} from waste are known in the art. An example is depicted in 30 Figure 2. In this example, the particulate matter is fed into the gasifier 12 through an inlet 13 to form a bed of particulate matter 14. The upper layer of the particulate undergoes flaming pyrolysis (and is at a temperature of approximately 500°C},

13

whilst the lower layer is held at a higher temperature (which may be approximately 1000°C] resulting in gasification. Syngas is formed and may be drawn through the top 15 of the gasifier 12, or may be sucked through the bed of particulate matter and exit via a syngas outlet 16 at the lower end of the gasifier 12. There is also 5 generally an ash outlet 17 to remove ash from the bottom of the gasifier 12.

Although a conventional gasifier can be used to obtain syngas in the presently described process, in a preferred embodiment the inventor has found that by making certain changes in the layout and running of a conventional gasifier it is 10 possible to obtain syngas with lower cleaning requirements than for conventional gasifiers. An improved gasifier 12' is shown in Figure 3. In the improved gasifier, the particulate matter is fed into the gasifier 12' through an inlet 13' and the bed of particulate matter 14' is kept than a much lower depth than with a conventional gasifier. As the particulate size is small and low density it will rapidly undergo 15 pyrolysis. Preferably the depth of the bed is less than 0.5m, most preferably approximately 300mm. To allow for this, it is preferable that the gasifier is provided with a substantially flat lower surface (c.f. a conical or sloped lower surface that is often found in a conventional gasifier] which has a relatively large surface area. The gasifier is also kept at a temperature of approximate 800°C above the bed 14'. 20 Maintaining this temperature above the bed destroys any tar that may be present, resulting a no/low tar gasifier. Air is drawn in through an air inlet 18' at the lower part of the gasifier, the particulate matter undergoes pyrolysis and syngas is formed and is drawn off via a syngas outet 16' at the top of the gasifier 12'. Ash is removed from the lower part of the gasifier 12' and collected in an ash collector 20.

25

The resulting syngas is then drawn through a cyclone 19 to remove any remaining particulates. It will be understood that, due to storage issues it is preferable to use syngas quickly. In a preferred embodiment the syngas is sucked from the gasifier/cyclone using an eductor system 21, and channelled into a thermal oxidiser 30 22. It is important to keep the syngas in an inert/sealed system where possible to prevent unwanted ignition. The eductor system 21 is positioned downstream from the thermal oxidiser 22 and has a steam inlet upstream of the oxidiser and

14

downstream of the gasifier. Notably, the fan does not draw from the gasifier, only from the thermal oxidiser. Syngas leaving the gasifier is spray cooled to less than 530°C such that it is then drawn through the oxidiser by the eductor due to the pressure differential. The eductor system is generally understood to work using the 5 venturi effect to draw the syngas into the oxidiser 22.

The resulting gas may then be cleaned if required. This is known technology for those skilled in the art and may, for example, include retaining the gas at 260°C-300°C to prevent the formation of sulphuric acid. The stream is dosed with sodium 10 bicarbonate 25 in order to neutralise the stream which is then passed through ceramic filters 26. Finally, the stream is passed through a deNoX reactor 28 which contains a catalyst (such as a rare earth metal] to which ammonia solution is added. The deNoX reactor 28 converts nitrogen oxides into diatomic nitrogen, N2, and water, H20.

15

The resulting steam from this system and process can be used as required. In the preferred embodiment the steam is used to power one or more systems or processes in the tanning process. For example the steam can be utilised in the hot water system, or machinery that is used in the tanning process can be powered by 20 the steam (this may require some machinery to be adapted to be steam driven however the mechanisms for this are well known in the art]. The benefit of using the steam in this cyclical manner is that the overall process of tanning or leather making requires less fossil or carbon fuels as the waste itself is being used to replace much or all of the fuel that is required. There is also less waste being produced as 25 the sludge effluent which was previously sent to landfill is now being converted to heat energy.

Again, as already indicated it would be clear to one skilled in the art that the methods, systems and apparatus is for the processing of all tannery effluent waste. 30 Although the specific example given above refers to sludge, this could equally refer to waste from the further processing of tanned hides (which does not include fleshings waste which would not itself be considered tannery effluent waste].

15

Claims

Claims

1. A method of utilising tannery processing waste, comprising the steps of; drying said tannery processing waste;

5 milling said dried tannery processing waste to produce particulate matter;

pyrolising and gasifying said particulate waste to obtain syngas; and oxidising said syngas to produce heat.

2. A method of utilising tannery processing waste as in Claim 1 wherein the

10 tannery processing waste is sludge waste or sludge effluent obtained from the treatment of tannery waste effluent.

3. A method of utilising tannery processing waste as in Claim 1 wherein the tannery processing waste is trimmings, shavings or buffing dust obtained

15 from the further processing of tanned hides.

4. A method of utilising tannery processing waste as in Claim 1 wherein the heat is used to produce steam.

20 5. A cyclical method of utilising tannery processing waste as in Claim 1 wherein the heat energy is utilised by the tannery.

6. A method of utilising tannery processing waste as in any of the previous claims wherein the drying of said sludge waste takes place in a flash drier.

25

7. A method of utilising tannery processing waste as in any of the previous claims wherein the drying and milling of said tannery processing waste takes place in an attrition mill flash drier.

30 8.

A method of utilising tannery processing waste as in any of the previous claims wherein the particulate matter has a particle size of less than 1mm.

16

9. A method of utilising tannery processing waste as in any of the previous claims wherein the particulate matter has a density of less that 0.4kg/m3.

10. A method of utilising tannery processing waste as in any of the previous

5 claims wherein the particulate matter has a particulate size and density that is sufficient to allow predominantly all of the particulate matter to undergo flaming pyrolysis rather than incineration when exposed to appropriate temperatures.

10 11. A method of utilising tannery processing waste as in any of the previous claims wherein the particulate matter is cyclonically separated.

12. A method of utilising tannery processing waste as in any of the previous claims wherein the temperature of particles in the particulate matter does

15 not exceed 70°C during milling and/or separation.

13. A method of utilising tannery processing waste as in any of the previous claims wherein the attrition mill flash drier flash dries the sludge waste.

20 14. A method of utilising tannery processing waste as in any of the previous claims wherein the pyrolysis step occurs at temperatures of greater than approximately 400°C.

15. A method of utilising tannery processing waste as in any of the previous

25 claims wherein the pyrolysis and gasification step occurs at temperatures of approximately 800°C.

16. A method of utilising tannery processing waste as in any of the previous claims wherein the pyrolysis and gasification of the particulate matter

30 occurs in a gasifier.

17

17. A method of utilising tannery processing waste as in claim 14 wherein the layer of particulate matter in the gasifier does not exceed 0.5 meters in depth.

5 18. A method of utilising tannery processing waste as in claim 14 wherein the layer of particulate matter in the gasifier does not exceed 0.3 meters (300mm] in depth.

19. A method of utilising tannery processing waste as in any of the previous 10 claims wherein any remaining particulates are removed from the syngas.

20. A method of utilising tannery processing waste as in claim 17 wherein particulates are removed using a cyclone.

15 21. A method of utilising tannery processing waste as in any of the previous claims wherein the gas stream from the oxidation of the syngas is cleaned.

22. A method of using of utilising tannery processing waste , comprising the steps

20 obtaining tannery processing waste from the tanning process;

processing tannery processing waste;

utilising said tannery processing waste in the method of claims 1 to 21

23. A method of using of utilising tannery processing waste as in claim 22

25 wherein the tannery processing waste is kept separate from any fleshings waste.

24. A tannery processing waste utilisation system comprising;

a drier which is adapted to receive said tannery processing waste; 30 a mill which is adapted to break down the dried tannery processing waste into particulate matter;

18

a gasifier, positioned downstream from the mill, said gasifier being adapted to receive the particulate matter and flamingly pyrolise said particulate matter to produce syngas;

a thermal oxidiser, positioned downstream from the gasifier, said oxidiser 5 adapted to receive and burn the syngas to produce heat.

25. A tannery processing waste utilisation system as in claim 24 which is in the form of a thermal energy plant.

10 26. A tannery processing waste utilisation system as in claim 25 wherein the thermal energy plant is in close proximity or is part of a leather processing plant.

27. A tannery processing waste utilisation system as in any of claims 24 to 26 15 wherein the mill breaks down the dried waste into particulate matter with a particle size of less than 1mm.

28. A tannery processing waste utilisation system as in any of claims 24 to 27 wherein the mill breaks down the dried waste into particulate matter with a 20 density of less that 0.4kg/m3.

29. A tannery processing waste utilisation system as in any of claims 24 to 28 wherein the mill grinds the dried waste into a particulate matter which has a particulate size and density that is sufficient to allow predominantly all of 25 the particulate matter to undergo flaming pyrolysis rather than incineration when exposed to appropriate temperatures.

30. A tannery processing waste utilisation system as in any of claims 24 to 29 wherein the drier and mill are combined.

30

31. A tannery processing waste utilisation system as claim 30 wherein the combined drier and mill is an attrition mill flash drier.

19

32. A tannery processing waste utilisation system as in any of claims 24 to 31 wherein the gasifier has an internal temperature of greater than 400°C.

5 33. A tannery processing waste utilisation system as in any of claims 24 to 32

wherein the gasifier has an internal temperature of approximately 800°C.

34. A tannery processing waste utilisation system as in any of claims 24 to 33 wherein the base of the gasifier has a large surface area.

10

35. A tannery processing waste utilisation system as in any of claims 24 to 34 wherein the base of the gasifier is substantially planar and flat.

36. A tannery processing waste utilisation system as in any of claims 24 to 35

15 wherein an eductor system is used to draw the syngas from the gasifier into the thermal oxidiser.

37. A tannery processing waste utilisation system as in any of claims 24 to 36 wherein the heat obtained from the oxidation of the syngas is used to

20 produce steam.

38. A tannery processing waste utilisation system as in any of claims 24 to 37 wherein the gas stream exiting the thermal oxidiser is cleaned.

25 39. A thermal energy plant for utilising tannery processing waste from the tanning process, comprising the system of claims 24 to 38.

40. A thermal energy plant as in claim 39 which is in close proximity to, or is directly connected with, one or more leather processing facilities.

30

41. A method of utilising tannery processing waste substantially as described herein and with reference to the relevant figures.

20

42. A tannery processing waste utilisation system substantially as described herein and with reference to the relevant figures.

43. A thermal energy plant substantially as described herein and substantially shown in figure 4.

21

amendments to the claims have been filed as follows

1. A method of utilising tannery processing waste, comprising the steps of; drying said tannery processing waste;

milling said dried tannery processing waste to produce particulate matter; pyrolising by flaming pyrolysis and/or gasifying said particulate matter to obtain syngas; and oxidising said syngas to produce heat, wherein the particulate matter has a particle size of less than 1mm and a density of less that 0.4kg/m3.

2. A method of utilising tannery processing waste as in Claim 1 wherein the tannery processing waste is sludge waste or sludge effluent obtained from the treatment of tannery waste effluent.

CO 15 3. A method of utilising tannery processing waste as in Claim 1 wherein the tannery processing waste is trimmings, shavings or buffing dust obtained from the further processing of tanned hides.

10

o

20 heat is used to produce steam.

\J 4. A method of utilising tannery processing waste as in Claim 1 wherein the o

5. A cyclical method of utilising tannery processing waste as in Claim 1 wherein the heat energy is utilised by the tannery.

25 6. A method of utilising tannery processing waste as in any of the previous claims wherein the drying of said sludge waste takes place in a flash drier.

30

7.

A method of utilising tannery processing waste as in any of the previous claims wherein the drying and milling of said tannery processing waste takes place in an attrition mill flash drier.

22

8. A method of utilising tannery processing waste as in any of the previous claims wherein the particulate matter is cyclonically separated.

5 9. A method of utilising tannery processing waste as in any of the previous claims wherein the temperature of particles in the particulate matter does not exceed 70°C during milling and/or separation.

10. A method of utilising tannery processing waste as in any of the previous 10 claims wherein the attrition mill flash drier flash dries the sludge waste.

11. A method of utilising tannery processing waste as in any of the previous claims wherein the pyrolysis step occurs at temperatures of greater than 400°C.

12. A method of utilising tannery processing waste as in any of the previous claims wherein the pyrolysis and gasification step occurs at temperatures of 800°C.

13. A method of utilising tannery processing waste as in any of the previous claims wherein the pyrolysis and gasification of the particulate matter occurs in a gasifier.

14. A method of utilising tannery processing waste as in claim 13 wherein the 25 layer of particulate matter in the gasifier does not exceed 0.5 meters in depth.

15. A method of utilising tannery processing waste as in claim 13 wherein the layer of particulate matter in the gasifier does not exceed 0.3 meters

30 (300mm) in depth.

CO 15

o o

20

23

16. A method of utilising tannery processing waste as in any of the previous claims wherein any remaining particulates are removed from the syngas.

17. A method of utilising tannery processing waste as in claim 13 wherein 5 particulates are removed using a cyclone.

18. A method of utilising tannery processing waste as in any of the previous claims wherein the gas stream from the oxidation of the syngas is cleaned.

10 19. A method of using of utilising tannery processing waste , comprising the steps obtaining tannery processing waste from the tanning process;

processing tannery processing waste;

utilising said tannery processing waste in the method of claims 1 to 18

15

20. A method of using of utilising tannery processing waste as in claim 19 wherein the tannery processing waste is kept separate from any fleshings waste.

20 21. A method of utilising tannery processing waste substantially as in any of the previous claims and as described herein and with reference to the figures.

•.'????.• INTELLECTUAL

*.*. .V PROPERTY OFFICE

24

Application No: GB1303399.8 Examiner: Mr Martin Price

Claims searched: 1-23,41 Date of search: 10 April 2013

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category

Relevant to claims

Identity of document and passage or figure of particular relevance

X

1-23,41

WO 2007/037768 A1 Gep Yesil - see e.g. claim 1

X

1-23,41

WO 2009/020442 A1 Detes Maden - see e.g. claim 1

X

1-23,41

WO 2009/016649 A1

CSIR - see e.g. claims 1, 2 and examples, 2, 3, 5, 6

X

1-23,41

WO 2007/081296 A1

Gep Yesil - see e.g. claim 1 and the abstract

X

1-23,41

EP 1577367 A1

Petrobras - see e.g. claims 1, 12

X

1-23,41

FR 2769319 A1

Poitou Charentes - see e.g. claim 1 and WPI abstract number 1999-397321

X

1-23,41

CN 102634360 A

Fujian Tianke - see WPI abstract number 2012-Q23393

X

1-23,41

IN-B0024197-A- Sushash - see WPI abstract number 2010-D29952, document unavailable

Categories:

X

Document indicating lack of novelty or inventive

A

Document indicating technological background and/or state

step

of the art.

Y

Document indicating lack of inventive step if

P

Document published on or after the declared priority date but

combined with one or more other documents of

before the filing date of this invention.

same category.

&

Member of the same patent family

E

Patent document published on or after, but with priority date

earlier than, the filing date of this application.

Field of Search:

x

Search of GB, EP, WO & US patent documents classified in the following areas of the UKC :

Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk

•.'????.• INTELLECTUAL

*.*. .V PROPERTY OFFICE

25

Worldwide search of patent documents classified in the following areas of the IPC

C10B; C10J

The following online and other databases have been used in the preparation of this search report

EPODOC, WPI

International Classification:

Subclass

Subgroup

Valid From

C10J

0003/00

01/01/2006

A62D

0003/20

01/01/2007

C10B

0053/00

01/01/2006

C14C

0099/00

01/01/2006

Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk