Patent Application
20190010414
The present invention refers to a method for treating agricultural or forestry or urban origin biomass or mixture of different origin's biomass feedstocks, low quality coal such as peat, lignite or subbituminous or/and bituminous coal, or/and mixtures of them, garbage and urban/industrial wastes, solid and/or liquid state, as well as sewage treatment plant sludges by means of removal of inorganic elements, such as silica, potassium, sodium, chlorine, sulfur, phosphorus, nitrogen and heavy metals such as zinc, mercury, copper, lead, chromium, etc., and the addition of new inorganic elements such as calcium, magnesium, titanium, zirconium, yttrium, aluminum and ammonium, in order to produce a purified and upgraded solid and/or liquid material which can be used as raw material in thermochemical conversion processes such as combustion, flash (t<1 sec)/fast pyrolysis (1<t<10 sec), as well as in the gasification for the production of energy, and/or hydrogen-rich gas and liquid hydrocarbons which can be further upgraded by applying commercially available thermochemical conversion technologies for the production of pure hydrogen, liquid fuels, chemicals and energy with great economic and environmental benefits.
The excessive use of fossil fuels such as coal, oil and natural gas nowadays for energy/heat production as well as liquid and solid/gaseous transportation fuels causes major environmental problems such as emissions of sulfur and nitrogen oxides, particulates, heavy metals, methane and carbon dioxide. Additionally, the mining processes cause pollution of the local environment and especially of water, air and soil.
Aiming to reduce the gaseous/liquid and solid emissions caused by the use of conventional fuels and especially to reduce emissions of gases that contribute to the greenhouse effect, the use of renewable energy sources such as wind, solar, hydro and biomass is encouraged. Especially the use of biomass in solid and liquid form to produce liquid and gaseous biofuels which will not contribute to the greenhouse effect is highly important for solving that problem.
In addition, the recycling and recovery of urban and/or industrial waste and municipal waste such as garbage, wastewater treatment sludges, etc., is nowadays one of the biggest environmental problems worldwide. Every year, millions of tons of waste require safe as well as economically viable disposal and recovery. The most common disposal method is storing wastes in dumps followed by incineration and recycling to produce new materials. However, the high content of garbage and wastes in alkali metals, chlorine, sulfur and heavy metals make their thermochemical application problematic, costly and very low efficient.
The problems caused nowadays during the thermochemical incineration, combustion, gasification and pyrolysis of biomass is due to the ash composition. These problems occur especially when biomass derived from agricultural, forest and urban environment such as various kinds of straw, different kinds of waste from agricultural industries such as cotton, peanut olive, etc., as well as from trimmings and wood residues from construction and furniture production. Similar problems occur when you use low-quality coal such as peat, lignite and subbituminous/bituminous coal, used mainly for power and/or heat generation on a large scale, as well as urban and industrial origin wastes and wastewater treatment sludges which are intended to be used for safe, economically viable and environmentally beneficial treatment/deactivation/deposition. The ash of these specific biomass types is very rich in alkali metals, chlorine, sulfur and phosphorus, therefore the gases, liquids and solids produced during the thermochemical conversion of that biomass types tend to react with each other and with any other inorganic compounds present during the conversion, as well as with the metal surfaces creating corrosion problems, deposits and agglomerates. They also generate emissions which result in great financial losses, environmental problems and in the inability to use certain types of biomass on a large scale, separate and/or combined with solid or gaseous fuels for power generation, liquid fuels and chemicals production. Similarly, the ash of many low-quality coal fuels such as peat, lignite and subbituminous/bituminous coal appears to be also rich in alkali metals, chlorine and sulfur, where the ash composition differs depending on the coal quality and the specific characteristics of each coal deposit.
Consequently, similar problems, although of lower intensity compared to with biomass use, are observed, which lead to financial losses, environmental problems, and limited efficiency in the use of such coals, as well as to problems in their application as in the case of gasification of lignite with high sodium and chloride content for energy and/or liquid fuels production.
Additionally, the remaining ash from urban and industrial origin wastes and wastewater treatment sludges is rich in alkali metals, chlorine, sulfur, and phosphorus as well as in heavy metals such as zinc, lead, copper, chromium etc., which makes their thermochemical application problematic, costly and very low efficient.
Moreover, the existence of large amounts of chlorine in the structure of polymers/plastics such as polyvinyl chloride (PVC), which is present in a large amount of plastics included in solid wastes, results in the production of large quantities of dioxins (PCDD) and furans (PCDF), which are not only harmful for human health but also for other forms of life. The removal/destruction of these pollutants before being emitted to the environment requires the use of very expensive technologies of high accident risk.
Solving these problems will result in further use of biomass, urban and industrial origin wastes both in solid and liquid form and wastewater treatment sludges for the production of energy, liquid fuels and chemicals as well as for the economic and efficient use of coal with major economic and environmental benefits especially nowadays when the imported energy cost appears to be rising and greenhouse gases from solid fuels should be reduced. The increased use of biomass or/and urban and industrial origin wastes as well as the more efficient use of low-quality coals used on a general basis for energy production are expected to contribute decisively not only to the reduction of greenhouse gases and to the emission of sulfur oxides, nitrogen, heavy metals and particles that pollute the environment and human health, but also in the cost reduction of energy and fuel production.
The currently applied techniques and methods dealing with these problems appear to have only limited success and, as a consequence, the use of biomass in thermochemical conversion appears to be, worldwide, very limited, and restricted mainly in feedstocks like wood which presents fewer problems. As far as the use of low-quality coals is concerned, the specific problems limit their thermochemical conversion efficiency and lead to the use of larger amounts of feedstocks for the production of energy and fuels/chemicals, causing the increase on greenhouse gas emissions and the financially non-efficient exploitation of the coal deposits with larger content of alkali metals, chlorine and sulphur. Various pretreatment technologies have been proposed to reduce the problems caused by the thermochemical conversion of coal, biomass and waste but they have limited success with disproportionately high costs and they all fail to control and eliminate effectively all those different factors such as silicon, alkali metals, chlorine, sulfur, phosphorus, heavy metals, nitrogen, etc. that lead to the aforementioned problems. Examples of such methodologies which put a limit on the above problems are described in: Bender (U.S. Pat. No. 4,560,390), McMahon (U.S. Pat. No. 4,304,571), Grant (U.S. Pat. No. 4,137,050).
The purpose of this invention is to achieve the upgrading and purification of agro/forest/urban origin biomass or mixture of biomasses of different origins, low quality coal such as peat, lignite or subbituminous and/or bituminous coal, or mixtures of them, urban and industrial origin wastes and wastewater treatment sludges by removing the harmful inorganic elements such as silicon, sodium, potassium, chlorine, sulfur, phosphorus, nitrogen and heavy metals such as cadmium, chromium, nickel, lead, mercury, arsenic etc., and/or by deactivating them so that they do not adversely affect the thermochemical conversion processes such as combustion, flash/fast pyrolysis and gasification which are used to produce energy and/or gaseous/liquid hydrocarbons in case of pyrolysis and gas in case of gasification, which can be used for the production of pure hydrogen and/or liquid fuels/chemicals having zero footprint regarding greenhouse gas emissions and high financial value.
The invention is able to minimize/eliminate corrosion problems, deposition, ash agglomeration, and gaseous emissions (potassium, sodium, chlorine, sulfur, nitrogen and phosphorus), heavy metals (Cu, Pb, Zn, Cr, Hg, As, Mo, etc.), dioxins and furans (PCDD, PCDF) during thermochemical incineration, combustion, gasification, pyrolysis of the raw material used, e.g. agro/forest/urban origin biomass or biomass mixtures of different origins, coal or coal mixtures of different origins, low quality coal such as peat, lignite or subbituminous/bituminous coal, garbage and urban/industrial wastes, solid and/or liquid state, as well as sewage treatment plant sludges.
The invention is defined in independent claim 1. Features of the dependent claims add further advantages to the invention.
The intended purpose as surprisingly found in the laboratory is achieved by leaching of agro/forest/urban origin biomass or biomass mixtures of different origins, coal or coal mixtures of different origins, low quality coal such as peat, lignite or subbituminous/bituminous coal, or mixtures of them, garbage and urban/industrial wastes, as well as sewage treatment plant sludges with aqueous solutions of inorganic and/or organic salts and bases under pressure using the reactor depicted in
The novelty of this invention is based on the fact that it's the first time when the simultaneous removal of all harmful inorganic elements (Si, K, Na, P, Cl, S, heavy metals, nitrogen) and/or their deactivation is possible to such a large extent that the resulting upgraded/clean solid and liquid materials are able to be used in thermochemical conversion processes (combustion, gasification, pyrolysis) without emissions, corrosion, deposition, etc. problems at the lowest possible cost and greater energy efficiency and financial benefit.
As surprisingly found in the laboratory, the combined use of the innovative reactor illustrated in
As depicted in
Simultaneously, the parallel reactor operates one step back from the initial reactor in order to realize a process which is semi-batch but in progress at any time.
When the material reaches the second compartment of the pressurized reactor, the second pretreatment stage takes place. This step includes the leaching of the material with an aqueous solution of inorganic and/or organic salts. Mixtures of both organic and inorganic acids/salts can be used in the process to achieve the desired effect while the proportion of acid is limited to less than 30% of the total mixture on a weight basis and preferably to such an extent that will not create acidic conditions of pH less than 5 in the pressurized solution. The process conditions are temperature between 110-160° C. and pressure 2-10 atm if the material is biomass, temperature between 140-195° C. and pressure 4-20 atm if the treated material is coal, garbage/waste while pressure 4-45 atm and temperature (140-245° C.) in case of plastics/polymer materials especially if they have a chlorine containing structure, for less than 5 minutes in case of biomass and less than 20 minutes in case of coal, garbage/waste and plastics/polymer materials. Regarding organic and/or inorganic compounds, they are/can be used any water-soluble organic/inorganic salts of calcium, magnesium, titanium, zirconium, yttrium, aluminum and ammonium in proportions of 0.07% up to 4% weight basis in aqueous solution depending on the type of the treated material. In case of biomass, solvent concentration can be reduced to 0.5-1.5% and in case of coal and garbage/waste typically ranges between 0.5-4%. Additionally, all organic and/or inorganic acids that create water-soluble salts with the aforementioned cations can also be used. The acids concentration when acids/salt mixtures are applied is sufficiently low so that the pH of the solution is always higher than 5, preferably 6.5. Although the use of higher concentrations of salts in the solutions is feasible, it is not considered as necessary to achieve the desired result. After the end of the process, the solid-liquid separation as well as the solid removal from the pressurized reactor takes place in the same way as previously described and as shown in
The conditions inside the pressurized reactor are always slightly acidic/neutraValkaline depending on the use of suitable solvents as previously described. This fact combined with the low pressure (2-10 atm) and temperatures (110-168° C.) in case of biomass, pressures (2-20 atm) and temperatures (110-195° C.) in case of coal/garbage/waste and pressures (4-45 atm) and temperatures (140-245° C.) in case of plastics/polymer materials especially when they contain structural chlorine, results in the use of much cheaper materials such as carbon steel for manufacturing the pressurized reactors so that the process cost, both capital and operating, appears to be reduced by 50-80% compared to reactors that use much higher temperatures and pressures while their operating conditions are mildly to strongly acidic.
The pre-treatment consists of two stages in case of coal as well as biomass/garbage/waste whose ash contains silicon in large percent usually above 10% SiO2 in ash basis, which should be removed in order to reduce deposition problems, ash production and to create new high-value materials such as pure silicon. In any case and if necessary, materials having less silicon content in the ash can be used for upgrading. In that case, the first pretreatment stage is to remove the silicon from the treated material. This reaction is carried out at temperatures between 110-150° C. and pressure 2-10 atm when the material is biomass while at 130-195° C., pressure 4-20 atm when the material is coal and/or garbage/waste so that the aqueous phase remains in liquid form and is not converted to gas. Although higher temperatures (200-350° C.) and pressures could be used, the financial cost of such an option combined with the small additional benefits for the process itself, make such a choice unprofitable. This leaching process is performed by using aqueous solutions of strong bases and/or salts of strong bases such as potassium, sodium. This does not prevent the use of other active ingredients bringing the same result. The reaction time is now limited below 5 minutes in case of biomass while in case of coal, waste, etc. materials the treatment time ranges from 5 to 20 minutes, the solid/aqueous phase ratio can range from 15 grams per liter to 800 grams per liter depending on the treated material where the higher solid/liquid ratio is observed in case of coal and waste/litter, and the solution concentration of strong bases and/or salts of strong bases below 1.5% weight basis where better results are obtained for concentrations of 0.5-1% weight basis. This does not prevent the application of higher concentrations or reaction times if it is considered to achieve a better or different result. This process leads to the reaction of silicon with the strong alkali forming a water soluble alkali compound such as the KSiO3 while removing silica from the treated material by over 80% and up to 100% applying the appropriate conditions. Simultaneously, short residence and reaction time limit the reaction of alkali metal with the organic phase of the material and consequently the material loss. The treated material is initially size reduced using appropriate equipment so that the size of the treated particles are limited below 5 mm and preferably less than 2 mm, although larger particle sizes can be used if the pretreatment conditions are modified.
After the end of the first pretreatment stage, the resulting material has increased concentration of alkali metals and minimum silicon content. The removal of the liquid phase from the solid one and the solid transfer from the first to the second pressurized compartment is described in the operating principle of the pressurized reactor. The removed liquid is recycled to the process several times until it is saturated in silicates. Then it is further processed for collecting the silicon dioxide which is a high value material and can be used to produce pure silicon by applying commercially available methods.
In the second pressurized compartment, the material is now washed with an aqueous solution of inorganic and/or organic salts. Mixtures of both organic and inorganic acids/salts can also be used in the process to achieve the desired result considering that the proportion of acid is limited to less than 30% of the total mixture on a weight basis and preferably the extent of which does not lead to the creation of acidic conditions having a pH less than 5 in the pressurized solution.
Regarding organic and/or inorganic compounds, they are/can be used any water-soluble organic/inorganic salts of calcium, magnesium, titanium, zirconium, yttrium, aluminum and fluoride in proportions of 0.07% up to 4% weight basis in aqueous solution depending on the type of the treated material. In case of biomass, solvent concentration can be reduced to 0.5-1.5% and in case of coal and garbage/waste typically ranges between 0.5-4%. Additionally, all organic and/or inorganic acids that create water-soluble salts with the aforementioned cations can also be used. The acids concentration when acids/salt mixtures are applied is sufficiently low so that the pH of the solution is always higher than 5, preferably 6.5. Although the use of higher concentrations of salts in the solutions is feasible, it is not considered as necessary to achieve the desired result.
Examples are salts of calcium acetate/citrate/nitrate and/or magnesium acetate/citrate/nitrate and/or ammonium acetate/citrate/nitrate. Also acetic acid, citric acid, nitric acid could be used. When magnesium, titanium, aluminum, yttrium, zirconium and/or ammonium salts are used, the addition of calcium salt to the mixture ranging from 1/10 up to ⅓ of the total salts concentration is always recommended for better results. However, the calcium salts can be used separately without the presence of other salts.
This reaction is carried out at temperatures between 110-160° C. and pressure 2-10 atm when the material is biomass while at 140-195° C., pressure 4-20 atm when the material is coal and/or garbage/waste so that the aqueous phase remains in liquid form and is not converted to gas. Although higher temperatures (200-350° C.) and pressures could be used, the financial cost of such an option combined with the small additional benefits for the process itself, make such a choice unprofitable. The reaction time is now limited below 5 minutes in case of biomass while in case of coal, waste, plastic etc. materials the treatment time ranges from 5 to 20 minutes, the solid/aqueous phase ratio can range from 15 grams per liter to 800 grams per liter depending on the treated material where the higher solid/liquid ratio is observed in case of coal and waste/litter.
The applied ratios depend on the type and composition of the pretreated material (e.g. biomass, coal, garbage/waste, etc.) as well as on the desired properties which are going to be applied to the pretreated material. Regarding the creation of the aqueous solution, any kind of water from the public water system, source, etc., can be employed. During the treatment with the aqueous solution of the organic and/or inorganic solvent which is created by mixing the specific organic and/or inorganic water-soluble salts and/or acids, the alkali metals (K, Na), sulfur, phosphorus, the heavy metals (Cu, Pb, Zn, Cr, Hg, etc.) as well as the chlorine present in the structure of the treated materials are transferred into the aqueous phase and are removed from the pretreated material mainly as inorganic/organic salts.
Simultaneously, cations such as Ca, Mg. Al, Ti. Zr, NH4, etc., replace hydrogen atoms and/or alkali metals and others, inside the structure of the treated materials thereby increasing the concentration of these cations in the treated materials. This is concluded to have a surprisingly positive effect on the thermochemical conversion reactions such as combustion, flash/fast pyrolysis and gasification which favors the production of energy without deposition/emission problems, the production of purified hydrogen-rich gas, and/or pure liquid phase hydrocarbons with high conversion efficiency which can be further used for the production of pure hydrogen and liquid fuels/chemicals with low financial cost.
After the second pretreatment stage, the clean/upgraded solid/liquid end product which now contains very small to zero silicon, alkali metals, phosphorous, sulfur, chlorine and heavy metals concentration as well as increased cations concentration used in the last process step (Ca, Mg, Al, Ti, Zr, NH4, etc.) is separated from the liquid phase in the same way as described in the operation of the pressurized reactor, while the liquid/aqueous phase is recycled back to the process.
Purification of the liquid phase from inorganic elements such as potassium, sodium, phosphorus, sulfur, chlorine, heavy metals is carried out after several loops using ion exchange resins when sign of saturation of the aqueous solution with the specific components is occurred.
In case that the pretreated material contains less than 10% SiO2 ash basis, or only silicon traces as in all kinds of plastics, RDF (refuse derived fuel), etc., biomass such as peach kernels, DDGS, etc., for which silicon is considered that there is no reason to be removed from the treated material, then the material is washed with an aqueous solution of inorganic and/or organic salts, mixtures of both organic and inorganic acids/salts considering that the proportion of acid is limited to less than 30% of the total mixture on weight basis and preferably the extent of which does not lead to the creation of acidic conditions having a pH less than 5 in the pressurized solution.
In this case, both separate pressurized compartments from each parallel reactor illustrated in
Examples are salts of calcium acetate/citrate/nitrate and/or magnesium acetate/citrate/nitrate and/or ammonium acetate/citrate/nitrate. Also acetic acid, citric acid, nitric acid can be used. When magnesium, titanium, aluminum, yttrium, zirconium and/or ammonium salts are used, the addition of calcium salt to the mixture ranging from 1/10 up to ⅓ of the total salts concentration is always recommended for better results. However, the calcium salts can be used separately without the presence of other salts.
This reaction is carried out at temperatures between 110-160° C. and pressure 2-10 atm when the material is biomass, between 140-195° C., pressure 4-20 atm when the material is coal, garbage/waste, between 140-245° C., pressure 4-45 atm when the material is plastic especially with high chlorine concentration such as poly-vinyl chloride, or other synthetic material so that the aqueous phase remains in liquid form and is not converted to gas. Although higher temperatures (250-350° C.) and pressures could be used, the financial cost of such an option combined with the small additional benefits for the process itself, make such a choice unprofitable. The reaction time is now limited below 5 minutes in case of biomass while in case of coal, waste, plastic etc. materials, the treatment time ranges from 5 to 20 minutes, the solid/aqueous phase ratio can range from 15 grams per liter to 800 grams per liter depending on the treated material where the higher solid/liquid ratio is observed in case of coal, RDF and waste/litter, longer reaction times can also be used if necessary depending on the treated material as well as on the desired properties which are going to be applied to the pretreated material.
After the end of the pretreatment process, the clean/upgraded solid/liquid end product which now contains very small to zero silicon, alkali metals, phosphorous, sulfur, chlorine and heavy metals concentration as well as increased cations concentration used in the last process step (Ca, Mg, Al, Ti, Zr, NH4, etc.) is separated from the liquid phase in the same way as described in the operation of the pressurized reactor, while the liquid/aqueous phase is recycled back to the process.
Purification of the liquid phase from inorganic elements such as potassium, sodium, phosphorus, sulfur, chlorine, heavy metals is carried out after several loops using ion exchange resins when sign of saturation of the aqueous solution with the specific components is occurred.
The following examples are presented in order to indicate the effect of the invention on various materials such as biomass, coal, tires. However, the implementation and results of the method are not limited by the examples given here.
Wheat straw is treated at elevated pressure using the reactor shown in
Olive kernel is treated at elevated pressure using the reactor shown in
Then both the untreated and the treated material are used in fast pyrolysis tests (t=2 sec) at 600° C. These tests showed that the material conversion into gaseous and liquid products was increased from 80% to 93% at 600° C. after pretreatment. At the same time, although SO2 was produced in the final gaseous and liquid products during pyrolysis of the raw material, there was no presence of SO2 in case of the treated material. Additionally, the production of liquid hydrocarbons appears to be decreased by more than 85% in case of the treated sample while the primary end product is a gas mixture rich in H2, CO, CH4, and other hydrocarbons.
Coal (HSMc) from a US Mine is treated at elevated pressure using the reactor shown in
Then both the untreated and the treated material are used in fast pyrolysis tests (t=2 sec) at 600° C. and 800° C. These tests showed that the material conversion into gaseous and liquid products was increased from 41 to 75% at 600° C. and from 70 to 85% at 800° C. after pretreatment. At the same time, although SO2 was produced in the final gaseous and liquid products during pyrolysis of the raw material, there was 90% reduction in the presence of SO2 in case of the treated material. Additionally, the production of liquid hydrocarbons appears to be decreased by more than 80% in case of the treated sample while the primary end product is a gas mixture rich in H2, CO, CH4, and other hydrocarbons.
Coal (EBWM) from a US Mine is treated at elevated pressure using the reactor shown in
Then both the untreated and the treated material are used in fast pyrolysis tests (t=2 sec) at 600° C. and 800° C. These tests showed that the material conversion into gaseous and liquid products was increased from 48 to 73% at 600° C. and from 65 to 80% at 800° C. after pretreatment. At the same time, although SO2 was produced in the final gaseous and liquid products during pyrolysis of the raw material, there was 92% reduction in the presence of SO2 in case of the treated material. Additionally, the production of liquid hydrocarbons appears to be decreased by more than 80% in case of the treated sample while the primary end product is a gas mixture rich in H2, CO, CH4, and other hydrocarbons.
Used car tires are treated at elevated pressure using the reactor shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 20160200056 | Dec 2015 | GR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2016/057999 | 12/24/2016 | WO | 00 |
