Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10F—DRYING OR WORKING-UP OF PEAT
  • C10F5/00—Drying or de-watering peat

Definitions

• the present invention relates to a multi effect hydrolysing/drying system for biological materials and related means and methods.
• the present invention relates to an improved procedure in relation to such procedures, methods, etc. which provide several options for an operator of such plant or
• the present invention is directed to processes and related products and related plant which provide some options or at least provides the public with a useful choice.
• the invention comprises a combustion process comprising
• step (III) subjecting the at least partly dried, washed and at least partially hydrolysed material of step (III) while still in a steam environment of elevated temperature(s) and pressure(s) to either a powder forming or gasification or pyrolysis or solvolysis process, and
• step (IV) feeding the powder or gas produced by step (IV) from its pressurised step (IV) environment into a combustion chamber and combusting the powder or gas therein.
• a washing step takes place both before and after step (II).
• the washing between steps (I) and (III) is at a pressure at least as high as about the lower of the end pressure of step (I) and the initial pressure of step (III).
• step (I) involves a series of different steam/solid entrainment systems the operating pressures of which progress serially upwardly.
• step (I) the pressure or end pressure of step (I) is at about 35 bar and the steam is at at least saturation temperature.
• the steam is at at least saturation temperature.
• at least some volatiles produced in step (I) are removed from the ongoing solids stream to step (III).
• step (III) is at an elevated pressure and the steam environment is at at least saturation temperature.
• the steam environment in step (III) has as some stage between 15 °C to
• step (III) involves a series of different steam/solid entrainment systems.
• step (III) is operated at a pressure of greater than about 20 bar.
• a powder is produced by step (IV).
• a milling procedure to produce the powder is operated under the steam atmosphere at a pressure of from about 20 to about 30 bar.
• the solids in step (IV) are milled dry and/or wet down to a mesh size of less than 50 microns.
• wet milling is used.
• step (IV) involves a gasification or pyrolysis or solvolysis process.
• pyrolysis of the solids material occurs in a steam environment at a temperature in the range of about 200 °C to about 1000 °C.
• the pyrolysis temperature is in the range of from 700 °C to 1000° C.
• said combustion chamber is the combustion chamber of a gas turbine engine.
• the pressure or end pressure of step (III) is at least as high as the pressure of step (IV), and the pressure of step (IV) is greater than that required for injection into said combustion chamber of said gas turbine engine.
• the invention consists in a combustion process comprising I) subjecting a lignocellulosic and/or cellulosic material to at least partial hydrolysis in steam at elevated temperature (s) and pressure(s),
• step (I), or subsequent thereto, or both subjecting the materials to washing at an elevated temperature
• step (III) subjecting the at least partly dried, washed and at least partially hydrolysed material of step (III) while still in a steam environment of elevated temperature (s) and pressure(s) to either a powder forming or gasification or pyrolysis or solvolysis process, and
• step (IV) feeding the powder or gas produced by step (IV) from its pressurised step (IV) environment into a combustion chamber and combusting the powder or gas therein.
• the invention consists in a process for producing an at least partially hydrolysed and at least partially dry lignocellulosic and/or cellulosic material comprising
• step (I) prior to step (I), or subsequent thereto, or both, subjecting the materials to washing at an elevated temperature
• step (III) having a steam environment at elevated temperature(s) and pressure(s) to reduce the water content thereof, the pressure(s) of step (III) being less than that at the end of step (I) and the injection procedure being of a kind to shred the solids material; and IV) thereafter (a) harvesting the solids from step (III) or (b) combusting the solids from step (III) in air (directly or optionally after powder forming or gasification in a steam environment), and
• step (III) harvested under step (IV)(a) to briquette formation and/or blending with oil to create a fuel slurry.
• the injection procedure is of a kind involving an injection nozzle and an impingement grid and/or screen, the movement through the injection nozzle being as a result of the pressure differential between the environment of the incoming material and
• step (III) Preferably prior to harvesting or combusting the shredded at least substantially dried material of step (III) is subjected to a milling procedure.
• the invention consists in a process for preparing a hydrolysed, substantially dry, biological material which has a reduced tendency for formation of vitreous ash products should it be burnt comprising: (I) subjecting a biological material to a steam entrainment then collection system to achieve at least partial hydrolysis;
• step (III) harvesting the substantially dry, substantially hydrolysed solids from the steam system of step (II); the process being characterised in that: there is included prior to step (II) and/or step (I) at least one water based washing step at an elevated temperature.
• said biological material is a lignocellulosic material.
• said material is wood chips and/or bark.
• said steam entrainment of step (I) involves a series of discrete systems.
• thermodynamic/heat exchange inter-relationship so as minimise the input of heat from outside of the overall system.
• thermodynamic/heat exchange inter-relationship in the steam entrainment system of step (I) extends also to such a relationship with the downstream steps and the environments thereof.
• step (I) is at a pressure and temperature such as to provide for the biological material a saturation steam condition.
• said washing step (II) is subsequent to a preliminary steaming of the biological material.
• the invention is a process for preparing a solids fraction low in vitreous ash forming elements selected from potassium and sodium from a biologically sourced material having such elements, said process comprising: i) subjecting the materials to steam in a high pressure steam system into which energy and/or water as required may be added while extracting volatiles from said material; ii) passing the heated solid streams from the system of step i) into an elevated temperature washing step or sequence; and iii) removing much of the washing water from said solids stream to thereby provide the solids fraction low in said elements.
• said high pressure steam system is a steam/solids entrainment system.
• step (iii) is input into a hydrolysis process as claimed in our New Zealand Patent Specification No. 229080 (European Equivalent Application No. 90304922.9 and Australian Equivalent Application No. 55013/90).
• washing water removed by steps (iii) is used as a heat exchange liquid for an optional prewashing step prior to step (i)
• the system of step (i) is an entrainment system having heat exchange input, the entrainment system including a blower therein and a collection cyclone for the solid stream.
• said heat exchange input is by means of a fluid jacket.
• step (ii) Preferably said cyclone passes into step (ii) for a sequence of more than auger or other type washer capable of first allowing washing water to act on the solids stream and
• the solids being squeezed by said one auger or other type washer is capable of forming a plug with said material.
• washing water to said sequence of washing augers is counter current.
• the invention is a process of treating a biological material having
• a cellulosic content and having a potassium and sodium content (the "source material") in a multi effect hydrolysis and drying sequence which comprises: a) subjecting the source material at a first elevated temperature and first elevated pressure to a steam treatment b) taking the solids stream through a washing step [or sequence of washing steps]
• step d) taking the at least substantially hydrolysed material from step c) into at least one drying treatment in a steam environment; and e) thereafter extracting the solids stream in a substantially dry form from step d).
• steam treatment of steps (a) is with superheated steam.
• step (a) is after prewashing and/or the removal of at least some of volatiles thereof.
• step (b) is a washing step of the solids stream less its volatiles content removed earlier.
• the invention is an improved hydrolysis/drying process for biological materials comprising:
• step III) taking the at least partially hydrolysed solids stream from step II) into a combined hydrolysis/drying treatment at a second elevated pressure and a second elevated temperature substantially without flashing for a period;
• pre-treatment step (I) comprises
• such elevated temperature and pressure of said optional steam pre- treatment step is above 180° C.
• said optional steam pre-treatment step has steam with superheating.
• such elevated temperature and pressure of said optional steam pre- treatment step is at a pressure of about 12 bar and there is superheating in the range of 1°C to 30 ⁇ C of superheat. 5
• said superheating is about 20 ⁇ C.
• Preferably volatiles are extracted from solids steam during said optional steam pre- treatment.
• pre-heating treatment involves a washing step or sequence of steps
• washing is with water at an elevated temperature passing current through auger plug forming washers or washer.
• said pre-heating treatment also includes a saturated steam treatment stage preferably after the washing step or steps that follows a first steam treatment, such saturated steam treatment preferably being at about 24 bar (about 222 °C saturated).
• such system is an entrainment system and including a blower and a collection cyclone for the solids stream.
• a first hot wash step Preferably there is a first hot wash step, a first steam subjection step preferably with making up of water therein, a washing and drying step or steps and then a saturated
• the hydrolysis/drying step of III) is preferably in two parts irrespective of whether or not the step of III) is in two parts.
• the hydrolysis is in an entrainment and collection system (preferably
• cyclone collection for a pre-determined time at an elevated pressure of about 35 bar in saturated steam (about 242 °C saturated) for a brief period of time, eg. from for example 25 10 seconds to 90 seconds.
• an elevated pressure of about 35 bar in saturated steam (about 242 °C saturated) for a brief period of time, eg. from for example 25 10 seconds to 90 seconds.
• the drying step of IV is at a pressure of above atmospheric pressure but very much below that of the hydrolysis stages.
• the pressure is of the order of 2 bar with a degree of superheating, (eg. about 150° C superheated steam) with a dwell time therein for so long as is required to reduce the water content therein down to the level required for the end purpose of the materials, whether it be for burning, panel or product forming purposes or other.
• a degree of superheating eg. about 150° C superheated steam
• the system is operated in a manner substantially as herein described.
• the invention is a method of treating a cellulosic biological material which comprises subjecting the material to a controlled hydrolysis at about 35 bar for a period of 10 seconds to 90 seconds in steam, then without any substantial pressure change and without any significant flashing, subjecting the solids stream, for a period of 15 seconds or less, to another steam environment in a saturation or a superheated condition and thereafter drying the solids stream at a pressure of about
• the moisture content has been reduced to about 1% by weight
• the controlled hydrolysis reduces the water content of the solids fraction by about 80% or more by weight.
• the energy for the system is from a thermal input largely supplied in a counter current manner.
• the invention is plant for performing a process or method of the present inventions.
• the invention is a product or heat energy generated by a process or method of any one of the present inventions.
• Figure 1 is a diagram showing the apparatus diagrammatically over its various
• Figures IA and IB are, together, an enlargement of Figure 1 showing the various components thereof more clearly;
• Figure 2 is a diagrammatic view primarily of the solids stream showing the sequence of preferred steps of the pre-treatment process referred to with respect to Figures 1, IA and IB;
• FIG 3 is a similar diagram to that of Figure 2 but carrying on therefrom showing the hydrolysis/drying steps in the preferred form of the invention (evaporation 1 being a steam system that is a merger of both a continuation of the hydrolysis stage and a commencement of the drying stage);
• Figure 4 is a diagram taken from Canadian Patent No. 1213711 of K Shen in
• FIG. 5 in a similar manner to that shown in Figures 1, IA and IB, there is shown an overall preferred process providing a primary atmospheric wash and preheating stage, a third preheater stage (first steam carrier stage) with volatile separation, a three stage wash from the first steam carrier stage into a second steam carrier stage (fourth preheater stage), transfer from that second steam carrier stage into a primary hydrolysis stage, and
• Figure 6 is a flow diagram showing a system in accordance with the present invention with its primary heater secondary heater hydrolyser evaporator etc leading into a powder producing system for feeding a gas turbine, such downstream system including a ball mill etc, and
• Figure 7 shows a variation of the system shown in Figure 6 to the extent that instead the downstream process is to generate a combustible gas by ultra pyrolysis in a steam environment to then be burned and to drive a gas turbine.
• Bio materials such as those typically containing lignocellulosic or cellulosic materials such as wood based materials, straw, rice husks or the like are all capable of being used in a process described in our earlier mentioned patent specifications. Such materials can also be used in much the same way in the processes, plant and apparatus of the present invention.
• the present invention provides certain enhancements over the prior art process of our earlier patent specifications.
• T R Miles discloses that high levels of alkali in annual crop biomass fuels create serious fouling of convection surfaces and slagging of fluid beds and grates in combustion boilers. As a consequence, only minimal percentages, 5 to 15%, by weight of these fuels can be fired in combination with other fuels notwithstanding the need for frequent cleaning of the systems. He additionally states that such deposits seriously limit the potential recoverable energy from agricultural residues in particular. High alkali content of these fuels forms an eutectic with silica lowering the ash softening point to as little as 750° C from 1050° C for stem wood ash. The problem occurs even with low percentages of agricultural residues fired with stem wood.
• the present invention when operated, at least in its preferred mode, overcomes such difficulties to at least an extent and provides an option such that the
• system can, if desired, be operated to deal with such agricultural residues (organic material) with or without cellulosic content and/or, optionally, can be operated to provide with certain input materials, (eg. wood, straw and/or rice husks) a hydrolysed substantially dry solid stream capable of being pressed as disclosed in our aforementioned patent specification into useful products.
• certain input materials eg. wood, straw and/or rice husks
• Figure 2 deals with a pre-treatment stage which preferably elevates the temperature of the solid stream while at the same time, in the preferred form, washes, from the solid stream, water soluble values which are frequently high in unwanted alkali metals (potassium and sodium), preferably after removal of some of the volatiles.
• a pre-treatment stage which preferably elevates the temperature of the solid stream while at the same time, in the preferred form, washes, from the solid stream, water soluble values which are frequently high in unwanted alkali metals (potassium and sodium), preferably after removal of some of the volatiles.
• Figure 2 shows a pre-wash step, a first steaming step (preferably with entrainment and collection in a cyclone), a series of washing steps and then a second steaming step prior to onfeed of the solids stream into the hydrolysis/drying flow referred to with reference to Figure 3.
• the pre-wash is with hot water, preferably sourced directly or indirectly from extracted superheated vapour from evaporation stage 2 referred to in Figure 3.
• superheated vapour can either be condensed or used to heat the water for such pre ⁇ washing.
• the pre-washing is in a column as shown in Figures 1 and IA with the column or other form being jacketed and maintained at an elevated temperature by the solids laden water resulting from the washing steps.
• Water used for the pre-wash is preferably taken by auger into the steam 1 system where optional water can, if required, be added to make up for that steam being lost along with solids being passed to the wash step as well as being extracted with the volatiles.
• the steam 1 step is a pre-heater stage in the form of an entrainment system powered by an appropriate blower with the water level being made up by optional water injection and with the solids stream being extracted into the first of preferably three washing steps from a cyclone. Heated by the thermal fluid heated by steam taken out of evaporation stage 1, the steam in the steam 1 system is at an elevated pressure of about 12bar with superheating. Saturation temperature at about 12bar is about 180 ⁇ C and the
• the hot wet solids are then auger fed through a series of preferably three washing steps into which water at an elevated temperature (preferably of or above the solids stream being washed) is provided prior to the water then being squeezed as a plug is formed prior to the auger passing the squeezed materials into the next auger region of the subsequent washer.
• the triple counter-flow washer with a squeeze out in each stage preferably has the pressurised hot water sourced from the condensate from a secondary thermal fluid heater and supplemented by make up water introduced from a heat exchanger.
• the heating of such materials can be sourced as appropriate preferably from within the system such that a single thermal fluid heater only is required so that much of the thermodynamic advantages from the prior art process of our aforementioned patent specifications is maintained.
• the wash water obtained from the washes is circulated at system pressure to heat
• the steam 2 system is preferably also an entrainment system with a blower and a solids collection cyclone passing via an appropriate pressure lock or solids stream transfer device to an auger for subsequent passage from there into the controlled hydrolysis stage
• the system referred to as steam 2 is heated by thermal fluid from the secondary fluid heater to about 24bar and contains steam at a saturated temperature of about 222 14
• the recirculating vapour is composed primarily of saturated steam.
• the increase of pressure is preferably, therefore, of the order of from atmospheric at outset to 12bar at the steam 1 system to about 24bar at the steam 2 system and then onto about 35bar at each of the controlled hydrolysis and evaporation 1 systems referred to with reference to Figure 3.
• the primary hydrolysis stage (the controlled hydrolysis) is heated by thermal fluid from the fired primary fluid heater to the pressure of, for example, 35bar (242° saturated).
• the extent of the hydrolysis is controlled by the timer unit which retains the solids in the system for a suitable accurately defined period for the particular solids stream determinable only by reference to the characteristic of the overall system and the input solids stream and the rate thereof.
• the recirculating vapour is composed of saturated steam.
• controlled hydrolysis if performed at 35bar, would take a period of time of no longer than from 10 seconds to 90 seconds prior to being passed, preferably without flashing, into the system labelled evaporation 1.
• heated by thermal fluid from the fired primary fluid heater and maintained at the same pressure as the preceding stage (the controlled hydrolysis) the temperature is raised to give the driving force for the evaporation of the majority of the moisture entrained in the solids.
• the falling rate drying period see Figure 4
• hydrolysis continues at the same rate as in saturated conditions. In the constant rate period the temperature rises so that the hydrolysis rate increases.
• Residence at the falling rate is shortened by the transfer of the solids to the next state. Preferably such transfer is within a period of 6 seconds or less to avoid damage to the material, eg. by 5 overcooking.
• the passage through a pressure lock and auger into evaporation stage 2 is into a lower pressure system, preferably with a pressure of about 2bar (150° C superheated)
• Desired end point eg. after evaporation 2 system moisture contents are preferably down to about 1% by weight (moisture/product).
• the evaporation 1 system optimally (on a wet basis) lowers moisture by about 80% or about 90%, ie. solids going into evaporation 2 system have only about 20% or 10% of the moisture entering the evaporation 2 system.
• prewash 0 and preheater for the solids inlet.
• the prewash gives rise to solubles laden water which is then subjected to water treatment for separation of solubles and other substances thus allowing water cleansed of unwanted content to be re-injected into the process and/or to allow surplus water to be disposed of in a suitable manner.
• the primary atmospheric wash and preheater system preferably uses a three stage
• the first steam carrier stage (third preheater stage) is the first steam entrainment system and includes a blower, a water injection system and a solids collection cyclone leading to a three stage counter current washer for the solids stream which is to transfer the solids from the first entrainment system into the second entrainment system (fourth preheater stage - second steam carrier stage).
• the first steam carrier stage is heated by thermal fluid from the secondary fluid heater to 12bar (188 ⁇ C saturated) plus 10°C of superheat. Volatile components are purged with a vapour stream to be condensed for separation.
• the hot, wet solids are washed in a triple counterflow washer with a squeeze-out in each stage.
• the pressurised hot water is sourced from the condensate from the secondary thermal fluid heater and supplemented by make up water introduced from a heat exchanger.
• the wash water containing soluble extractives is circulated at system pressure to heat the input of solids as it enters at atmospheric pressure. Water is finally processed to provide for utilisation of the solubles.
• the separation process with the downstream of the volatile condensate collection results in water condensate being returned to the reservoir while volatile oils separated therefrom are taken off as by-products or become a fuel.
• the three stage counter current washer preferably carries one third of the solids in each compartment separated by the squeeze-out plug.
• the dilution in each stage by use of condensate only is one part dry solids to two parts water. Reserve dilution can be at any level by use of a water bank but the purge rate is fixed by the incoming condensate. Squeeze-out is 1:1.
• the fourth preheater stage (the second steam carrier stage) is heated by thermal fluid from the secondary fluid heater to 24bar (222 °C saturated).
• the recirculating vapour is composed of saturated steam.
• the primary hydrolysis stage receives the solids from the fourth preheater stage (second steam carrier stage) via a solids transfer device previously described or optionally as disclosed in our Patents Specification No. PCT/NZ94/00097 (equivalent New Zealand Patent Application 248895).
• the primary hydrolysis stage is heated by thermal fluid from fired primary fluid heater to 35bar (242 °C saturated).
• the extent of the hydrolysis is controlled by the timer unit which retains the solids in the system for a suitable accurately defined period.
• the recirculating vapour is composed of saturated steam.
• the main or first evaporative stage is heated by thermal fluid from fired primary fluid heater and maintained at the same pressure as the preceding stage, ie; the 35bar of the primary hydrolysis stage.
• the temperature is raised in this stage to give the "driving force" for the evaporation of the majority of the moisture entrained in the solids.
• hydrolysis continues its same rate as in saturated conditions.
• the temperature rises so that the hydrolysis rate is increased.
• Residence at the falling rate is shortened by transfer of the solids to the next stage, optionally, via an injection nozzle and screen capable of shredding the solids owing to the rapid pressure drop between the main evaporative stage and the final evaporative stage.
• the final evaporative stage receives either through a pressure lock (or another solids transfer device) or an injection nozzle of the mason type (or any other suitable type) the solids from the preceding stage.
• the final evaporation stage is heated by the thermal fluid from the secondary fluid heater to 2bar (150 °C superheated). Pressure is reduced to provide 30 °C superheat for final removal of moisture.
• the product merges to atmosphere (if desired) as hot, dry, washed and hydrolysed fibre.
• the present invention recognises however, that at least at the main evaporative stage at least partially dry at least partially hydrolysed lignocellulosic material is contained in a high pressure steam system thus making it possible to perform on such a pressurised system, in such a steam atmosphere (which will not support combustion), processes (such as milling to a powder and/or gasification, for example, by ultra pyrolysis) to provide a product in a pressurised system which can, if desired, be used (either with mixing with oil or other components) as a fuel feed using the already existent pressurisation into an appropriate combustor (for example, a gas turbine).
• a downstream process avoids the need for an expensive dedicated fuel feed pressurisation system.
• Figure 6 shows downstream from a system of the kind as depicted in Figure 5 a downstream process flow by reference to diagrammatic apparatus. It can be seen that from the evaporator stage or stages a ball mill in conjunction with the appropriate ducting steam fan, dust separators etc can provide a powder capable of being fed to a combustor for heat generation purposes and, as shown, to use the exhaust gases to drive a gas turbine which in turn can generate electricity while still allowing use of heat from such exhaust gases by virtue of energy recovery procedures.
• Figure 7 is an alternative to arrangement shown in Figure 6 to the extent that an ultra pyrolysis apparatus is employed downstream of the evaporative stages and the gas generated thereby is likewise utilised as is the waste heat from the combustion of such gas.
• the final low pressure drying section referred to in relation to Figure 5 is not used and drying is carried out totally in the high pressure superheated section to whatever degree of dryness is considered best for the subsequent process.
• the mostly dried solids are entrained in a blow line which carry them to a nozzle from which the material is expelled complete with its carrier steam into a low pressure system, a pressure drop of about 5 to lObar maximum in the preferred form.
• the blow line into the reduced pressure system provides the potential for solids to be carried along the pipe towards the nozzle until the material in the carrier reaches the nozzle it remains that the pressure and temperature of the drying stage which it has left that is providing the temperature is not allowed to drop so that heat exchange jacketing becomes necessary.
• pulverising and powdering equipment is employed so that the desired fineness is achieved without loss of temperature or pressure in the system. It is important to note that there is no danger or fear or explosion in the pulverising and powderising operation because of the absence of oxygen. It should also be noted that further washing step can be inserted between the first high temperature hydrolysing system and the high temperature/hydrolysing/drying system.
• the gasification process is carried out in almost exactly the same way except that the material should be milled to small particles but not necessarily powderised.
• Some applications require the supply of biofuel in the form of a coarse powder with particle size around 1mm. and less than 2mm.
• Ultra-pyrolysis The ultra pyrolysis is effected in a final (or te ⁇ ninal) section of the process.
• the biofuel is supplied as a coarse powder.
• the pyrolysis takes place in less than a second.
• the temperature range is between 700 and 1000°C, preferably around 750°C.
• the ultrafast heating of the particle is effected through a range of options: -
• the ultra pyrolysis reaction can be shifted to optimise the production of a range of gases such as synthesis gas, ethylene, methane, by the use of gases additional to steam such as CH 4 (natural gas) or H 2 .
• gases such as synthesis gas, ethylene, methane
• gases additional to steam such as CH 4 (natural gas) or H 2 .
• the H 2 can be produced by water hydrolysis from the power generation stage, (with the 0 2 used to improve efficiency of char gasification).
• Additional a range of catalysts can be used to boost specific gas production.
• a medium temperature range say 200° - 700 °C can optionally be used. It is quite clear in reviewing the literature that the steam hydrolysis will not only facilitate the production of high calorific value gases and synthesis gas but also the production of what is known as "bio-oil” or proto-oil", that is to say the production of oils from biomass that contain a proportion of oxygenates and that can easily be upgraded through catalytic reforming processes into the equivalent of petroleum oils.
• Biopowder/oil slurries The combination of washes, hydrolysis, drying, hammer and wet milling results in the production of a range of biopowder slurries that can be used as a substitute to heating oils ranging from heavy fuel oil to diesel. These slurries are destined to be used in existing oil fired boilers and other heating devices (such as for the production of hot air for space heating) and district heating facilities. Besides the economic advantage, the use of biopowder slurries in substitution to oil products results in a significant lowering of atmospheric emissions (such as sulphur, C02). The use of slurries enables the use of existing boilers without major modifications to them.
• the slurries comprise from 5 - 60% biopowder combined with oil or similar
• the hydrolysis part of the process is instrumental in ensuring the quality and suitability of the final slurry product.
• vegetable or animal oil products can be used (such as esterified tallows, vegetable oils derived from palm oil, copra, etc).
• bio-oils that can be separated from residual ash and chars.
• Some of the bio-oil can be re-circulated as solvent as part of a continuous process. It may be that for some applications this is the best route to de-ash and produce a clean fuel (such as hog fuel processing).
• the resulting products can be used as a fuel or sold as "crude" for subsequent refining.
• the organic solvents are preferably derived from the volatiles vented at the front end of the process.
• Molten ash is formed because combustion reactions cause mineral ash substances to fuse at temperatures far below true melting points.
• the problem is not “ash” but the "lava” like product of fused ash components.
• the mineral ash components should evolve as a very fine and nonabrasive powder but the presence of volatile alkali salts effects the creation of the vitreous eutectic lava phenomenon.
• Alkali salts are a marked feature of annual growth or "green” biomass but are present in many fuels.
• Convertech provides for the removal of the alkali ash components before combustion. Removal of most of the alkali substances prior to firing radically changes combustion chemistry. The formation of sticky slag deposits which can occur at quite low furnace temperatures, is avoided to allow greatly enhanced combustion and heat transfer
• Fuel produced by the system will be substantially devoid of alkali salts, be totally dry and extremely brittle, it will be fibrous, relatively reactive and non-abrasive.
• Fuel powdering will be effected during transportation with no pressure or temperature losses. As powdered fuel is carried into the combustion chamber, the steam energy is utilised with the added benefit of reducing the emission of nitrous oxides.
• Additives to counter any tendency for vitreous ash formation can also be injected.
• the embrittled fuel can be finely powdered so that the particle burnout time is reduced to a minimum in combustion chambers of moderate size. Throttling and excess fuel control can also be provided for. If the formation of vitreous substances is prevented, the very low ash evolved will be of a fine, non abrasive character which will pass harmlessly through the turbine requiring flyash collectors and only occasional wash cycles.

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• 1993
  • 1993-10-07 NZ NZ24888493A patent/NZ248884A/en unknown
• 1994
  • 1994-10-06 CN CN 94194076 patent/CN1134683A/zh active Pending
  • 1994-10-06 EP EP94929051A patent/EP0724508A4/de not_active Withdrawn
  • 1994-10-06 BR BR9407768A patent/BR9407768A/pt not_active Application Discontinuation
  • 1994-10-06 AU AU78243/94A patent/AU700466B2/en not_active Ceased
  • 1994-10-06 CA CA 2173440 patent/CA2173440A1/en not_active Abandoned
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  • 1994-10-06 JP JP7510740A patent/JPH09505244A/ja active Pending

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