GB2388606A - Fuel composition comprising waste plastic in a hydrocarbon gel - Google Patents

Abstract

A fuel comprises granulated waste plastic mixed with a liquid hydrocarbon, such as paraffin or kerosene, and aluminium oxalate or a metal alkyl compound to form a gel. The plastic may comprise PET, HDPE, LDPE, PVC, PP or PS. Also claimed is converted plant to burn the fuel. Further claimed is a method of disposal of refrigerators, cars and electrical equipment by incinerating the items whole, possibly using the fuel of the invention.

Description

. 2388606

( PATENT APPLICATION

TITLE INCINERATION OF PLASTIC WASTE SUSPENDED IN PARAFFIN GEL

Brief Description of Plastic Incineration Process for Patent Application:

Stage I - All types of hard& soft plastic containers, car fittings, mouldings, etc., are shredded to pea size in a commercial shredder.

Stage 2 - Aluminium Oxalate is mined into commercial kerosene (paraffin) to produce gelled light diesel oil. This gel flows without sticking to the sides of the commercial nicer or any pipe into which it is pumped.

Stage 3 - The pea sized shredded plastic is mixed into the gel and held in suspension in the gel.

Stage 4 - The gel is fired in torroidal burners which produce a high intensity flame ( 1800 degrees Celsius) to incinerate all noxious gases Stage 5 - The heat produced during incineration is used to generate electricity, produce process steam, assist cement, lime or brick kiln performance, or destroy old cars, refrigerators and electronic equipment.

Introduction

The UK has an annual waste plastic disposal problem of some 400,000 Tons.

The current EU requirement to dispose of, or recycle, some 15% of this waste plastic is not met now nor will the new 25% legislation be met in 2005.

Because the EU requirements do not allow waste plastics to be chemically treated the only method of destroying plastic waste is by high temperature incineration.

This Patent Application describes a process of granulating the waste plastic, suspending it in paraffin gel and incinerating the gel mix to provide heat for electrical power generation or for industrial steam.

400,000 Tons of plastic waste could provide 6000 MW of power continuously per year, or one tenth ofthe UK's electricity requirements. Smaller weights of plastic could assist kiln outputs or destroy old unwanted domestic equipment.

Description of Each Stage of the 5- StaEe Process Listed Above

Stage 1 - Sorting: Collection: Economics of sorting & collection: Granulating Sorting of Plastic Waste Six types of plastic have been designated recyclable. These types are the more solid plastic e.g. bottles rather than plastic bags. They can be easily granulated.

The six types, described next page, are:

PET Polyethylene Terephthalate, flexible soft drinks & water bottles, HDPE High Density Polyethylene, rigid liquid & other containers, PVC Polyvinyl Chloride, heavy sheeting, LDPE Low Density Polyethylene, flexible soft plastic containers & tubing, l PP Polypropylene, ropes & spun fibre, PS Polystyrene, light foam pecking.

Sorting is either done by Councils supplying recycling facilities or by mechanical plant where plastic is "rumbled" (shaken out) from other rubbish e.g. bricks, wood, metal, and household waste. Sorting has a cost which is met from Council taxes. Economics of Treating Plastic Waste Collection has a cost plus delivery charges to a central baling plant. If the waste is washed the costs of water treatment have to be accounted. Baled plastic can be sold unsorted and unwashed for up to ú100/Ton to the Far East where labour costs to sort it are low and chemical effluent from the washing process is uncontrolled.

Recycled clean plastic granules will only realise ú40 to ú60/Ton in the KU.

The Calorific Value per ton of baled plastic waste is equal to that of coal valuing it at ú80/Ton. Given that the Far East market is illegal the economics of treating waste plastic as a fuel in the EU at ú80/Ton is the best option. And it gets rid of the bulk of 400,000 Tons/year instead of recycling 25% and land filling the remaining 300,000 Tons (UK figures only).

Baling & Granulating Waste Plastic - Well Known Process l The baling, shredding and granulating of plastic waste has been commercial for many years. It is part of the recycling process that eventually turns the granules into new plastic bottles, cloth for car roof linings and even nappy liners but this market is limited.

Three German companies manufacture plastic balers, shredders, & granulators: Weima Maschinenbau GmbH Bruckmann & Kreyenborg Granuliertechnik GmbH CKT Kunstoffverarbeitungstechnik GmbH Stage 2 Gel Production Alurninium chemical Gel Process To produce the gel, Aluminium Oxalate, a white powder is stirred into paraffin, kerosene or diesel fuel.

Note: Aluminium oxalate is non-toxic.

( Stage 3 - Mixing / Stimng of the Gel Stirring is done on a commercial scale of over 200 tons per batch using mixers which are electrically driven paddle wheels in large tanks and manufactured by: Plenty of Newbury, UK Lightin Mixers, USA These commercial mixers are operated by large oil companies, Esso, Shell, etc., to produce lubricating oils and also for butyl rubber in tyre manufacture.

The granulated plastic is then metred into and stirred into the gel in the same mixer. Ratios of the amounts of oxalate and plastic to paraffin are not declared in this Patent Application at this stage for commercial reasons.

Stage 4- Incineration Incineration of the Gel in torroidal burners The properties of the gel are that it does not 'Nvet" the sides of its container and behaves as a super fluid. It does not require much pumping power to feed a burner. It could be gravity fed to an incineration plant.

The torroidal burners in the incineration plant receive gravity fed fuelgel. They do not require atomised fuel in the nonnal way. Thus the granulated plastic suspended in the fuel-gel is incinerated to destruction within the torroidal flame generated by the air supplied to the burner.

Torroidal burners have been manufactured by: Wilson (Wallflarne), USA International Flame Research Foundation (IFRF), Ijmuiden, Holland.

University of Leuven, octagonal torroidal burners proven low pollutants, Belgium.

Patent believed applied during the 1960's - G Bathurst, Cirencester, UK.

Stage 5 - Use of Heat of Incineration Generation of steam or electricity 6000 MW of Power/Year available The major advantage of gelling shredded plastic waste is that it can be used as a first class fuel.

Because plastic is a hydrocarbon or carbon based material it has a Calorific Value in excess of coal and only slightly less than oil. When suspended in gelled paraffin the plastic waste will burn with the characteristics of oil fuel.

If the waste plastic is processed at one UK central site in large tonnages it can be utilised for electrical power generation on a huge commercial scale.

400000 Tons of plastic waste suspended in paraffin gel will provide the equivalent of three 2000 M\V Power Stations worth of electricity running continuously for one year. This is one tenth ofthe UK's electricity requirements.

If the waste is processed at several smaller sites it could be used for industrial I process steam in refineries, in cement, lime & brick kilns and burning old cars refrigerators and electronic goods such as computers and televisions.

The economics favour centralised electricity production by converting coal fired power stations to burn plastic suspended in fuel gel. The need for land fill sites to receive non biodegradable plastics would be largely eliminated.

Pollutant Control Plastics will give off noxious gases if not incinerated at a high enough temperature. Temperature and gas &: particle emission control are very necessary.

Converted power stations are the best option to exercise this control. If necessary after burners can be added to flue gas ducts to dissociate pollutants harmlessly.

Concluding Comment This process of incinerating shredded plastic waste suspended in a paraffin gel j would be of great interest to large industrial boiler makers who manufacture such plant worldwide for the generation of electricity. None of the well known manufacturers appears to have applied for an equivalent Patent to the one described in this application.

Equally none of the kiln producers or incinerator manufacturers have apparently patented plastic waste gelled fuel applications at this time.

Claims (1)

1. ( Claims in support of Patent Application for Plastics Incineration

   Claim 1. ( Claims 1 to 8 refer to making and transporting gelled fuel) It is claimed that this is the first time a fuel gel containing a fixed suspension of granulated plastic waste has been produced. The plastic granules will remain in fixed suspension indefinitely. Examples of the fuel gel suspension can be made available for visual examination.

   Claim 2.

   All types of plastic waste can be shredded and/or granulised. There is no need to sort hard from soft plastics. As part of the granualising process the plastic waste can be hot air dried. For effective combustion the granual size should be no greater than peas or smaller.

   Claim 3.

   The fuel gel suspension is exceedingly safe compared to liquid fuels. It is non corrosive. It cannot leak from punctured tanks. It has zero explosive vapour. It can be transported by road and rail, by sea, by pipeline and if necessary by air meeting all hazardous chemical transport laws.

   Claim 4.

   The fuel gel is dynamically stable (will not separate) and will withstand centrifuging for an hour at 1200 rpm (washing machine speed).; Claim 5.

   The suspended fuel gel- granulated plastic nurture exhibits psuedo nonNewtonian properties on pouring from a vessel. When poured slowly the gel hangs Dom th vessel but returns very quickly into the vessel when it is made upright. The poured gel demonstrates decreased viscosity with increasing strain rate. A demonstration is remarkable in that the gel appears to behave as a super-fluid. Claim 6. Follows: I Claim 6.

   The fuel gel can be pumped without undue power using existing commercially available pumps because of its psuedo non-Newtonian properties.

   Claim 7.

   Cheap fuel gel production costs are attainable: The base fuel, paraffin or diesel oil, is low cost for stationary Incineration or Power Generation purposes.

   The alunum gelling agent is low cost.

   The plastic waste is free of charge except for collection costs.

   Granulating or shredding the plastic waste is cheaper than grinding coal, (an equivalent fuel).

   Mixing the paraffin, gelling agent and granulated plastic is cheaper than, for example, the oil industry process of mixing additives into lubricating oil because it is not dependent on precise accurately mixed amounts or on lengthy mixing time.

   Claim 8.

   Mixing of the base paraffin, gelling agent and shredded waste plastic can be achieved using very large commercially available paddle driven mixers.

   À These are the same mLxers used in the oil industry to produce butyl rubber for car tyres and for stirring additives into lubricating oil.

   High tonnages of the mix can be made within hours sufficient to feed Power Stations or Incinerators at the rate of 10 to 100 tons/hour or as required.

   Claim 9. ( Claims 9 to 16 refer to the combustion of the gelled fuel) The calorific value of the gelled base paraffin and plastic waste is equal to or greater than the 18,000 Btus/lb of the base paraffin. It can burn with the same heat release, or greater as would paraffin, diesel oil, or kerosene.

   Claim 10.

   The gelled plastic waste fuel, referred hereafter as "the fuel", can be economically pumped using normal large capacity screw pumps.

   The screw pump will be lubricated by the fuel.

   The fuel is therefore very easy to handle.

   The fuel is supplied to "torroidally air controlled burners" in gel form (Drawing 9 for design principles).

   Claim 11.

   Torroidal burners do not require atomised fuel droplets or fuel mist to burn.

   Combustion is fully achieved by controlling the volume and velocity of the cyclonic air supplied above the burning gel. The gel is also supplied at a controlled rate direct from the screw pumps.

   Claim 12.

   The fuel will burn at high temperature. Base paraffin will produce name temperatures of 1800 degrees Celsius. At this temperature the suspended granulated plastic will have to pass through the borne, be subjected to the full 1800 Deg C flame temperature and be totally incinerated. Aderburning, as practiced in normal incinerators, may not be needed.

   Claim 13.

   No noxious gases will be produced in the combustion process. The 1800 Deg C flame temperatures will be high causing any chlorine, cyanogens, dioxin or other chemicals emitted by burrung plastic to be dissociated. Normal combustion products of water vapour, carbon dioxide and nitrogen oxide are to be expected.

   Claim 14.

   Combustion residues should be non-existent. The carbon based paraffin and plastic will be gasified. the gelling agent will oxidise / vaporise, and any residues will be the result of ineffective cleaning of the plastic during the granulating process. Although these will be misfire provision is made in the torroidal burners for "asking out" during maintenance periods.

   Claim 15.

   Coal f red power station furnaces, especially those nearing the end of their economic lives at the present time would be ideal conversion vehicles for burning gelled plastic waste filrl, "the fuel". The refractory lined furnace ash-pit could be converted into one large torroidal burner at rninirnal cost.

   There is no need to build expensive new incineration or power plant Drawing I attached shows the furnace and ash-pit conversion design. This is new technology andforms part of this Patent.

   Claim 16.

   Power station coal fired furnaces are designed to absorb radiant heat. Boiler, superheater and economiser tubes would not need modifying. Because coal is only 10,000 Btus/ lb calorific value compared to "the fuel" at 18,000 Btus/lb then only 55 percent of"the fuel" is required to meet the designed power output.

   Claim 17. (Claims 17 to 24 refer to Conversions of Existing Plant for this Patent) Electrical Power Generation Plant Conversion; Any coal or oil or lignite fired power station (Utility in the USA, Centrale in France) is convertible to gelled waste plastic fuel, 'the fuel". Gas fired plant, if not designed for radiant heat absorption, may need some superheater tubes to be removed.

   All of these differently fired power stations are covered by the conversion, Drawing I Thousands of Power stations worldwide are capable of conversion to "the fuel" to alleviate the pressing problem of ridding the Earth of waste plastic.

   Drawing 2 shows how coal/oil/lignite storage is converted to making "the fuel ".

   ( Claim 18 Incinerators, Conversion of Large industrial plant: Incinerators are being built currently to burn plastic and other household/industrial waste. These incinerators can use "the fuel" to achieve the same result. Pre-shredding or granulating the plastic would greatly assist the incineration process and decrease significantly the noxious gas effluent that is the source of public fear.

   Drawing 3 shows a schematic conversion of a typical incinerator. The fuel storage facility would be as Drawing 2.

   Worldwide there is a need to incinerate waste of all types to arrest the use of landfill sites. This Patent claims that landfill sites for domestic waste could be eliminated by using "the fuel". Some industrial toxic wastes could also be destroyed if'the fuel" flame temperature is maintained at 1800 Deg. C. (As described in Claims 12 and 13) Claim 19.

   Brick Kiln Conversion: Brick kilns use gravity fed heavy fuel oil to bring the kiln to clay flung temperature.

   Black heavy fuel oil is as thick as tar, has to be pre-heated, contains high percentage sulphur and is rich with heavy metals e.g. vanadium. It is difficult to pump and atomise, hence the simple gravity feed from the roof of the kiln.

   "The fuel" would greatly assist brick kiln operators and would not produce the large black carbon deposits on the floor of the kiln. Operating costs should be lower because no storage tank and fuel line trace heating would be required. Kiln downtime to remove the carbon deposits would be rare.

   Drawing 4 shows a Brick Kiln schematic conversion.

   Claim 20.

   Cement Kiln Conversion: Dry cement powder is produced by feeding crushed Portland Stone to inclined rotary kilns. At high temperatures above 1000 Deg C powdered cement is produced which sets on reaction with water. Temperatures must be sufficiently high to convert free sulphur to calcium sulphate or poor quality cement will result. "The fuel" meets the need to produce high temperatures.

   Cement kilns are usually fired by coal or heavy fuel oil because these fuels contain sulphur and iron impurities. The sulphur aids the production of calcium sulphate, a setting agent for cement, and iron is a catalyst allowing the cement to be made at lower temperatures.

   q ( High sulphur diesel oil (used on ships and railway engines to spread the sulphur oxides far and wide) would be an ideal gelled "the fuel" for cement kilns.

   It is further claimed that slowly rotating cement kilns using "the fuel" could be converted to incinerate domestic waste. Shredded domestic waste could be fed into the kiln instead of crushed Portland stone. The kiln is over 200 feet long. The residence time in the kiln can be hours rather than minutes. At cement kiln temperatures all waste including shredded metal would be oxidised to ash and gas.

   A bank of converted cement kilns on a single old landfill site would provide an excellent community incineration service.

   Drawing 5 shows a schematic Cement Kiln conversion.

   Claim 21.

   Lime Kiln Conversion: Lime is the second highest tonnage commodity produced after sulphuric acid. It is vital for water purification.

   The manufacture of quick lime is done by firing calcium carbonate (limestone) at high temperature using heavy fuel oil in inclined rotary kilns (USA) or vertical kilns (Europe). In the USA 90 percent of quarried powdered limestone is fed direct to the rotary kiln in an integrated process. These are ideal sites for gelled plastic waste Mel plants. In Europe "the fuel" would be trucked as for heavy oil.

   "The fuel" can be substituted for heavy fuel oil for the same reasons as described in the rotary cement kiln conversion. However the carbon dioxide product of combustion must be removed quickly. "The fuel" will make no difference to the limekiln performance.

   Drawing 6 shows schematic rotary and vertical limekiln conversions.

   Claim 23.

   Industrial Gas Turbine Conversions: Industrial gas turbines (not the aeroengine type) have been designed to run on heavy fuel oil. Their hot turbine blades have to withstand attack by sulphur, vanadium, sand and other impurities. The heavy final oil is preheated and pressurised to 1 500-psi minimum to make a combustible fuel spray.

   "The fuel" contains suspended plastic granules and cannot be spray atomised. Splash plate burner technology needs to be used in aero derivative gas turbines utilising axially radial combustion cans. The splash plate burner is annular supplying a "cannular" combustion can (e.g. Armstrong Siddeley Sapphire aero gas turbine ca 1960 service). The waste plastic would need to be shredded to 1 mm maxLmum size to meet splash plate technology.

   An easier gas turbine conversion would be the truly industrial gas turbine designed with a single large offline combustion chamber e.g. Ruston or Kongsberg said to be capable of burning peanut butter. These types would take "the fuel" with almost zero modification. Drawing7 shows a schematic of an industrial Gas Turbine burner conversion.

   Thousands of industrial gas turbines exist worldwide. Using them to burn plastic waste is an efficient use of a waste resource converting it to useful electricity.

   Claim 24.

   À Waste Heat Boiler Conversion: Waste heat boilers are added to industrial gas turbines to make use of the 600 Deg.C exhaust temperature from the engine. This high-energy exhaust stream would otherwise be lost. Known as Combined Cycle plant the gas turbine plus waste heat boiler can achieve efficiencies up to 72 percent compared to 14 percent from a car engine. The waste heat boiler needs extra fuel to raise the temperature from 600 to 1200 C. "The fuel" could be used to fire the waste heat boiler using torroidal burner technology as described in Claim 15.

   Drawing 8 shows a gas turbine waste heat boiler conversion schematic.

   Claims 25 to 27 refer to New Waste Disposal Applications for Refrigerators Cars and Electrical Equipment (TVs' Computers, Electronic Goods etc.) Claim 25.

   Refrigerator Disposal by Incineration Refrigerators are a major disposal problem because of the CFC refrigerant liquid held in the plastic insulation. Shredding refrigerators under negative pressure is a costly preparation and the incineration equipment is also too costly.

   Simpler disposal is proposed in this Patent by incinerating complete refrigerators in one piece in a very long residence time high temperature furnace (e.g. 3 hours instead of the usual 5 seconds). In several hours the refrigerator steel case alumniurn coolant coils compressor and insulation will have totally oxidised. Maintaining the furnace at negative pressure by an induced draft fan prevents CFC gas prematurely escaping. 'The fuel" would generate the high temperature in the furnace.

   Two long residence time furnaces could be used.

   a) Converted cement kilns fired by "the fuel" and adapted to take a feed hopper for full size refrigerators see Drawing 10. The rotational speed ofthe inclined

   ll kiln is adjusted to give the desired long residence time. Any metallic oxidised residues will gradually move down the inclined kiln for easy removal. This is the less costly alternative.

   b) Custom built long residence time incinerators of the two-chamber type where the intense flame heat is developed in the first chamber and the refrigerators are burnt to complete destruction in the second chamber. The second chamber would require auxiliary firing by "the fuel", see Drawing 11.

   Any metallic ash residues could be raked out at lengthy intervals.

   Claim 26.

   Television, Computers, Electronic Goods Disposal by Incineration Electronic goods contain plastics, exotic metals, tritiurn displays and printed circuit boards which must not be returned uncontrolled to the environment.

   Electronic items must be destroyed by incineration as the safest means of disposal.

   Again long residence time incineration is required and is achieved by feeding waste items into; a) Converted inclined rotary cement kilos, or b) Custom built two-chamber long residence incinerators, both of which are fired by 'the fuel".

   "The fuel" is used for initial firing and added to the bottom of the inclined cement kiln or to the second chamber of the custom built incinerator for secondary firing.

   Electronic items can be fed completely whole, no shredding is required, into the two types of incinerator described in a) and b) above, see Drawing 11.

   Unlike refrigerator incineration where removal of metallic oxide residues poses no threat to the environment, care must be taken with ash residues from electronic components. They may have traces of heavy metals and arsenic compounds.

   These minimal amounts of waste ash must be analysed to meet safe disposal limits.

   Claim 27.

   Cars, Automobile Disposal by Incineration Automobiles contain plastics, glass, steel and other metals, air conditioners, printed circuits, computers, oils, glycols, chemicals, paint and butyl rubber tyres. It is not economic to disassemble old cars to separate their plastic, metal, lyres and other components. Usually cars are drained of petrol, air conditioning fluids, glycol coolant and oils before scrap disposal. This practice must be maintained.

   The best economics are to crush the cars to a small solid block and incinerate the block over a long period (several hours depending on the weight of each block).

   Each block will weigh from 500 kilos (small car) to 3000 kilos (large car) .

   Long residence time modified brick kiln technology is the best solution using "the filet'' as the firing medium. Each car block is pushed into the preheated kiln. Up to 24 cars could be pushed into the refractory lined kiln for a 24 hour residence time burn, see Drawing 12.

   Metallic residues can be maurnised by lengthening the residence time in the kiln.

   Gaseous emissions are incinerated by afterburning if required.

   The alternative of melting the "car blocks" in an electric arc furnace was not economic. Costs of Incinerating Refrigerators, Electronic Goods and Cars À Refrigerators Based on refrigerator weights of 25 kilos to 100 kilos, Furnace residence time and fuel costs the price of incineration would be between ú20 and ú100 to be added to the initial production costs.

   Electronic Goods Electroruc Goods weigh from 10 kilos to 50 kilos. The Incineration disposal costs would be about ú10 to ú50 per item which has to be added to the initial production retail prices.

   Cars The cost of kiln incineration was calculated to be ú100 per car for fuel and handling plus a further ú80 per car for crushing and transport. This would add some ú200 per car onto initial production costs.

   This concludes the Claims Section.

   Final Note: Aluminium Oxalate has been nominated as the Gelling Agent, Other members of the metal allyl family can substitute. This Patent covers all gelling agents for the specific purpose of manufacturing granulated/shredded plastic waste suspended in base CnH (2n+2) paraffinic oils known herein as "the fuel".