Patent Application
20230374403
This method makes it possible to obtain a product with a high calorific value, low emission of toxic gases and ash, and low vitrification in the oven or stove as it is calcined, which corresponds in particular to lignin, cellulose, hemicellulose and derivatives thereof, with great energy savings in the process and low intensity of labour during operation.
In any industry that works with or emits biological waste, in particular in the management of slurry (cattle manure) in the livestock industry, which is a difficult problem to address, since it is a residue that can contaminate properties, groundwater and the environment in general. Likewise, there is concern regarding the sanitary management of agricultural manure in these industries.
Particularly, the manure generated can cause negative environmental impacts if there is no control of its storage, transportation or application, due to the emission of polluting gases into the atmosphere and the accumulation of micro- and macro-nutrients in the soil and in surface water bodies as the final destination for such manure.
The present development presents a system, a method and a biomass or derivative product with a high calorific value that is extremely efficient in contributing to the reduction of greenhouse gas emissions. In practice, it allows the replacement of fossil sources by biomass. Significant energy savings and efficiencies in labour intensity are generated during its production process.
The scope of application of this system, method and product includes the treatment of waste (solid and semi-solid) of biological origin, particularly in the livestock industry, biomass recovery systems for energy generation and biomass drying and preparation processes.
The livestock sector is responsible for 18% of greenhouse gas emissions measured in CO2 equivalents. This is a higher contribution than that of transport.
The livestock sector is responsible for 9% of anthropogenic emissions of CO 2. Most of this is derived from changes in land use, especially due to the deforestation caused by the expansion of grasslands for fodder. In addition, stabled animals, especially cattle, are responsible for the emission of gases with much greater potential to warm the atmosphere. This sector emits 37% of anthropogenic methane (with 84 times the global warming potential [GWP] of CO2) produced in the most part by the enteric fermentation of ruminants. It emits 65% of anthropogenic nitrous oxide (with 296 times the global warming potential of CO2), mostly through manure. Livestock are also responsible for nearly two thirds (64%) of anthropogenic ammonia emissions, which significantly contribute to acid rain and ecosystem acidification.
This high level of emissions opens great opportunities for climate change mitigation through actions with livestock (FAO Livestock's long shadow: environmental issues and options, 2006).
It should be noted that the livestock sector is responsible for 20% of terrestrial animal biomass.
As described in the present development, it is necessary to have methods for the treatment of manure, slurry and other residues of biological origin, with low energy consumption, that allow obtaining products with a high calorific value, with low concentrations of silica within the ash, low concentration of nitrogen, and which when burned release low concentrations of harmful gases. Intermediate products may also be produced that serve as an excipient base for other synthesis routes, such as products high in lignin but with traces of cellulose, hemicellulose and similar derivatives.
The livestock sector is a key factor in the increase of water use since it is responsible for 8% of the world consumption of this resource, mainly for the irrigation of fodder crops (FAO Livestock's long shadow: environment issues and options, 2009). In addition, it is probably the highest source of water pollution and contributes to eutrophication, the “dead” zones in coastal areas, coral reef degradation, the appearance of human health problems, antibiotic resistance and many other problems. The main sources of pollution come from animal waste, antibiotics and hormones, the chemicals used in tanneries, fertilisers and pesticides used on fodder crops, and eroded grassland sediments. That is why we must search for ways to reuse and decontaminate this liquid waste.
The development described herein partly mitigates the effects of livestock on water and soil contamination. (FAO Livestock's long shadow: environmental issues and options, 2009)
According to the FAO (http://www.fao.org/ag/againfo/programmes/es/lead/toolbox/Tech/21Mansto.htm), the Netherlands' standards for quantities of mixed manure (including faeces and urine but excluding sewage) produced by livestock annually, are:
Particularly, in the livestock industry, both manure and slurry generally correspond to a mixture of the the animals' faecal matter with their urine and eventually the bedding material, the latter being understood as the resting and feeding place for the animals.
The manure, in addition to containing faecal matter and urine, can consist of other elements, such as those present in the bedding, generally straw, and also sawdust, wood shavings, chemical products, sand, shells, bran, remains of the livestock feed, and water.
Manure is normally applied on the ground, providing organic matter to the soil. The contribution of organic matter entails an improvement of the soil structure and increases its water retention capacity.
On the other hand, manure is a rich source of plant nutrients (N, P, K).
The amount of nutrients and minerals present in manure depends on several factors, among which we can highlight the following: Type of livestock, livestock feed (which is directly related to the destination of the animal) and environmental conditions.
One of the elements that makes up manure is vegetable residue of different kinds, among which we can highlight lignocellulose and its derivatives.
Lignocellulose is a complex material that constitutes the main structure of plant cell walls and is composed mainly, in the case of cereals, of cellulose (40-50%), hemicellulose (25-30%) and lignin (15-20%), in the case of grasses (forage consumed by ruminants), the average percentages are divided into cellulose (24-39%), hemicellulose (11-39%) and lignin (4-11%). Cellulose is a homogeneous linear polymer with 7,000 to 15,000 glucose units linked by glycosidic bonds that are stabilised with hydrogen bonds. Hemicellulose is a branched or linear heteropolymer of between 200-400 units of different pentoses, hexoses and uronic acids with an amorphous structure. Lignin is a cross-linked amorphous polymer of three units of p-coumaryl phenylpropane, coniferyl, and alcohol. In order to decrease the world's dependence on fossil fuels, there are alternative sustainable energy sources and chemical products to be exploited. One of these possible sources is lignocellulose biomass such as wood or agricultural residues (Brethauer, S., & Studer, M. H. (2015). Biochemical Conversion Processes of Lignocellulosic Biomass to Fuels and Chemicals—A Review. CHIMIA International Journal for Chemistry, 69(10), 572-581).
Another element within the composition of slurry is made up of significant amounts of silica or derivatives thereof directly related to the amount of ash existing in its combustion. There are also other biological wastes with large amounts of silica in their structure, such as rice husks, which increase the percentage of silica in the final residue when they remain as part of the slurry (they cannot be digested) or simply as waste. It is important to make this reference to silica because when the finished products (briquettes, pellets or others) under any process modality are burned, the silica can reach temperatures above its melting point between 1100 and 1700° C., vitrifying the surfaces of boilers and ovens, causing them to lose heat exchange efficiency.
Another element in the composition of slurry is nitrogen, in the form of uric acid, such as ammoniacal nitrogen and other nitrogen derivatives. In bovine slurries the ratio is generally 50% uric acid and 50% ammoniacal nitrogen. As an example, one ton of nitrogen can be found in a 500 m3 well with a slurry having 4% solid mass. This concentration is important for soil nitrification, however, for the end product of this development in the form of ligno-cellulose briquettes or pellets to be burned it is a problem. The problem is that the generation of N-Oxides (NOx) after a combustion process is already known. These N-Oxides tend, naturally, to superoxidise, forming NO3 and with atmospheric water to form HNO3, a corrosive compound that is harmful to health and combustion equipment. Through another pathway, N2O can be formed, a product that is highly damaging to the ozone layer and very chemically stable, with a half-life of over 170 years. In summary, the nitrogen derivatives and percentages that remain in the end product are extremely important at the time of burning because they carry toxic, corrosive and persistent by-products into the environment. The patent by the same inventor PCT/CL2017/00009, mentions in its example of Table 18, 0.61% w/w of nitrogen in the end product. The present development manages to reduce this amount of nitrogen, approximately, by 30% w/w in the end product, based on the operation of the present process presented below. This is due to the fact that chemical reactions take place in the cavitation step, where O2 from the environment reacts and, to a greater extent, O3 that is injected with nitrogen from the treated slurry, generating NO, which decreases the final concentration of nitrogen in the end product.
Among agricultural residues we commonly find bovine slurries, which are available at very low cost, but with a non-negligible handling and disposal cost, where also, in order to reduce costs, the use of the product resulting from the treatment of these slurries without pre-treatment as fuel or fuel feedstock has been studied.
To date, techniques have been described for the detection and quantification of the content of the main components of manure (cellulose and protein), which use a solid/liquid physical separation method, manure hydrolysis and fungal culture to recover carbohydrates and proteins from the raw material in order to produce cellulase (Value-Added Chemicals from Animal Manure S. Chen, et al. Pacific Northwest National Laboratory, 2003). In the case of obtaining lignin from agricultural residues and assessing its quality by means of different analytical methods, this is basically done by subjecting agricultural residues to a reduction to alkaline paste, treating it with formic acid and hydrogen peroxide, to then characterise the lignin by means of the Klason method, FT-IR spectroscopy, elemental analysis, thioacidolysis, SEC and different wet chemical methods (Separation and characterisation of sulphur-free lignin from different agricultural residues Christine Rossberga, Martina Bremer, Susanne Machill, Swetlana Koenigc, Gerhard Kerns, Carmen Boeriud, Elisabeth Windeisene, Steffen Fischer, Industrial Crops and Products, VOL 73, pages 81-89, 30 October 2015).
Among the general techniques of mechanical separation in the liquid/solid fractions of manure most used in commercial plants is decantation by centrifugation, chemical treatment plus separation by belt press, rotary drum filter plus screw press, screw press plus vibration filter, sonication and screw press only. It is considered that only mechanical separation techniques are included that use moving filters and presses (Chemical and biochemical variation in animal manure solids separated using different commercial separation technologies, Karin Jorgensen, Lars Stoumann Jensen Bioresource Technology 100 (2009) 3088-3096).
In addition to the mechanical techniques for separating the liquid/solid fraction of manure, a separation method has been described by means of a coagulation-flocculation process, whose separation protocol consists of taking the raw manure stored at 4° C. and sieving it through a 1 mm mesh, then subjecting it to a coagulation/flocculation process according to the following conditions and steps: (1) for the coagulation process, coagulant solution was added and mixed for 2 min at 175 rpm; (2) for flocculation, a polyacrylamide solution is added and mixed for 13 minutes at 50 rpm; (3) the solid is allowed to form or settle during 2 hours, when the supernatant is extracted, or when for 5 minutes when a filter press is used to separate the solid fraction (Characterisation of solid and liquid fractions of dairy manure with regard to their component distribution and methane production J. L. Rico, H. Garcia, C. Rico, I. Tejero Bioresource Technology 98(2007) 971-979).
Another component that can be found in slurry is methane, a gas used as fuel. The yield and quality of this compound obtained from manure has been studied, with its results expressed according to the volatile solids (VS) parameter (Methane productivity of manure, straw and solid fractions of manure H. B. Moller, S. G. Sommer, B. K. Ahring, Biomass and Bioenergy 26 (2004) 485-495).
Additionally, there are processes for extracting manure products for other purposes. For example, document U.S. Pat. No. 4,018,899 A discloses a process for extracting food products from animal manure comprising: forming a manure water slurry in a first pit and allowing said slurry to ferment; then separating said suspension into solid and liquid fractions, where the solid fraction comprises a silaged component such as undigested fibres and grain; and where the liquid fraction comprises protein-rich nutrients and relatively indigestible dense mineral materials and fibre particles, ultimately separating said components and then processing the liquid fraction for use as a feed supplement containing relatively low amounts of indigestible minerals such as lignin and hemi-cellulose and fibre particles.
Documents WO 2015086869 A1 and ES 2171111 A1 present different procedures for slurry treatment. Document WO 2015086869 A1 discloses a procedure comprising: (a) solid/liquid physical separation in a liquid effluent containing slurry; (b) physical-chemical separation of the liquid fraction obtained in step (a), to obtain a solid and a liquid fraction; (c) electrocoagulation of the liquid fraction obtained in the step to obtain a solid and a liquid fraction; and (d) pelletising the solid fractions obtained in steps (a), (b) and (c) in the presence of chemical or lignocellulosic materials. In addition, this document indicates that the solid agglomerate obtained from the pelletising process offers a high calorific value in combustion, and the resulting liquid is left a very low content of nitrogenous compounds. Here it can be seen that the solid fraction is left with high levels of nitrogen because this element is found in low amounts in the liquid fraction. This results in a high amount of NOx emission when burning the pellets, briquettes or any solid form with this residue. Also, and as additional information, when NOx is emitted it has an unpleasant odour, which is part of the odour generated by pollutants when incinerated, such as heavy metals and high concentrations of ash.
For its part, document ES 2171111 A1 presents a procedure and a plant for the treatment of slurry, which comprises: (ii) carrying out a physical-chemical treatment on the liquid phase of the slurry to reduce the emission of ammonia contained in said slurry during the evaporation step, by means of stripping or fixation by acidification; (ii) subjecting the liquid stream resulting from step (i) to vacuum evaporation until obtaining a solids concentrate containing between 20% and 30% by weight of solids; and (iii) drying the solids concentrate from step (ii) until obtaining a product with a maximum moisture content of 12% that is useful as organic fertiliser, or enriched with a fertilising ammonium salt.
Documents WO 2011/133190 and US 2014/250776 present respectively products and processes for waste derived from different types of slurry. Document WO 2011/133190 describes a biomass composition, where this composition includes: (i) a lignocellulosic material; and (ii) at least one member selected from the group consisting of potassium, sodium, and chlorides, wherein said at least one member comprises no more than about 0.01% (by weight) of said composition. The composition may not include more than 10% water.
On the other hand, document US 2014/250776 presents a process for converting waste fibres into solid fuel, which includes the supply of animal waste, including the waste fibres, in a predetermined amount; flushing the animal waste supplied during a predetermined flushing period; dewatering the animal waste supplied by removing water from the waste fibres for a predetermined dewatering period; detachment of the waste fibres to separate liquids from solids; compressing the dried and separated waste fibres to generate a plurality of briquettes; roasting at least one of the plurality of briquettes in a roasting reactor using a heat source at a predetermined roasting temperature for a predetermined roasting period; withdrawing from the reactor at least one of the plurality of briquettes; and cooling the roasting reactor to reach a predetermined cooling temperature.
Also document US 2011/0089271 presents a method and a device, and the use thereof, to produce fuel pellets from wet biomass of any kind, where the biomass is shredded, mechanically dehydrated, dried, and then processed into pellets, where the shredded product is finely shredded and/or the biomass is washed either before or after the shredding, optionally with water extracted from the mechanical dehydration, and is optionally pre-dehydrated and/or heated before the mechanical dehydration step, and optionally ground again after mechanical dehydration by simple drying.
Processes that use ultrasound as a step in the separation of components are also described, such as in document CN 104611084, which discloses a method to produce a clean energy material from agricultural and forestry residues, producing a solid lignocellulosic material. The method comprises the steps of decomposition and separation of the solid lignocellulosic material from agricultural and forestry residues and the production of clean energy material. The material is fed into the system (step a)) via a screw conveyor, the interior of which is in communication with a chamber comprising an ultrasound generator that generates ultrasound vibrations in the presence of water (steps (b) and c)), causing the material to lose its microstructure, and in this state the material is subjected sequentially, with stirring, to primary crushing, dilaceration and liquid-solid separation (step (d)), compression and separation of components (step (e)) and finally the production of dry lignocellulosic material (steps f) and g)). On the other hand, as a summary, this patent includes in its process the expansive explosion of vapour, microwaves, heating, a number of extra chemical and biological processes, such as decomposition of cellulose. Finally, the product of this process is mixed with coal dust to obtain a product with a high calorific value.
Another document, in line with sonication is document US 20100304440, which discloses a method for processing biomass to obtain ethanol from plant residues. Where biomass (for example, plant biomass, animal excrement biomass, and municipal waste biomass) is processed to produce useful products such as fuels. For example, the systems may use as feed materials such as cellulosic or lignocellulosic, and/or starch- or sugar-containing materials to produce ethanol and/or butanol by fermentation, for example. The document also teaches that sonication breaks the lignin and cellulose bonds, creating bubbles that burst in the medium containing the lignin and cellulose, in order to better expose the residues from the bursting to biological processes. When the bubbles burst, which can occur in less than a nanosecond, the implosive force increases the local temperature inside the bubble to approximately 5100° K and generates high pressures. It also indicates that these materials are sonicated with a frequency range of 16 kHz to 110 Khz. These high temperatures and pressures break the bonds in the material. It also shows a general system in which a stream of cellulosic material mixes with a stream of water in a tank to form a process stream, where a first pump draws the process stream from the tank and directs it to a flow cell. The ultrasonic transducer transmits ultrasonic energy, causing the described physical-chemical process. It is also stated that, upon separation, the solid material dries and can be used as an intermediate fuel product.
Document DE 1020014116250 also proposes a method for treating a mixture of at least one liquid phase and at least one solid phase, in particular liquid manure or sewage sludge, comprising the steps of: a) generating an ultrasound field (5.1b-5). nb); b) transporting the mixture through the region of the ultrasonic field; c) treating the mixture with ultrasound in the region; and d) separating the mixture into the liquid phase and the solid phase after ultrasonic treatment. It also proposes that a suitable apparatus be available to carry out the process and use the solid phase generated by the process or apparatus. The objective of this method in general is to decrease the water content for the solid part between 1.8% to 3%, increasing the amount of nitrogen in the solid to make it a good fertiliser.
On the other hand, and aimed towards a chemical separation, it was found that document WO 2013007847 presents a treatment system for wastewater containing biological waste through electrocoagulation and electro-oxidation, which consists of the inclusion of slurry into a a slurry pit by means of a pumping system, where it is exposed to a solid/liquid separator or filter press. The process consists of sending the solids to a storage container to be dried through exposure to the open air or artificially to obtain soil fertilisers, while the liquids are sent to a flotation-flocculation tank. In this flotation-flocculation tank, sludge is generated that is sent to the filter-press, from which it is mixed with the solids coming fromthe storage tank, while the liquid matter is passed through electrocoagulation equipment for separation from the floating sludge, from the precipitated sludge and the clarified water that is sent to a tank. The floating sludge is transferred by decantation to the filter press, while the precipitated sludge is purged, and the treated water goes through a process where caustic soda is added to increase the pH and thus be included in an electro-oxidation step.
Documents WO 2009108761 and U.S. Pat. No. 6,149,694 disclose procedures for producing fuel from organic waste. Document WO2009108761 A1 discloses a process for producing fuel from liquid hydrocarbons from organic medical waste materials based on distillation treatments, through distillation towers or cracking towers. The procedure consists of preparing a suspension from the waste materials to form a stream, the volume of which stream accumulates in a stirred vessel. Subsequently, the stream is heated to a temperature between approximately 60-700° C. and a pressure between 20-600 psi to decompose solid organic materials and inorganic materials separately.
On the other hand, document U.S. Pat. No. 6,149,694 discloses a procedure for forming fuel from livestock waste, which comprises: (i) forming a mixture having a number of solid components derived from livestock waste and a second waste product different from said livestock waste, where the solid components have a moisture content before said formation step, and where the mixture formed has a lower moisture content than the solid content, and (b) forming the mixture resulting from step (a) into a self-supporting body having a density close to approximately 20-40 pounds/ft3. In summary, this patent presents a traditional solid/liquid separator by screw or screenin which about 40% to 60% of sawdust is added to make a pellet, where this product retains all the contaminants from its source residue, such as high concentration of ash, heavy metals, high concentrations of nitrogen, among others.
Documents CA 2670530, DE 102010019321 and US 20150004654 disclose procedures for the mechanical separation of the liquid and solid components of manure used as a raw material to produce fuel pellets. Of these, document CA 2670530 discloses that said pellet contains approximately 25%-75% by weight of cellulosic material (cellulose, lignin and hemi-cellulose); and approximately between 14%-75% by weight of waxed cellulosic material, which corresponds to lignocellulose to which a layer of wax was added. Specifically, the process disclosed mixes 42% of manure, with 40% of sawdust, cotton, jute, etc. and the remaining percentage with paper, cardboard, or another derivative of paper.
In the case of document DE 102010019321, it discloses a process to produce fuel pellets from an initial mixture made up of liquid and solid components, where said method consists of the following steps: separating the solid and liquid components, extracting energy from the liquid components and drying the solid constituents. The extraction of energy from the liquid components is based on a fermentation step.
Finally, document US 20150004654 discloses a process for producing biomass and sugar pellets from cellulosic material. In general, it describes a process of extraction of sugars from wood through hot water and/or vapour, followed by fermentation. It is a process to increase the calorific value of wood by eliminating the cellulose, to make it similar to the calorific value of coal and thus be able to replace it, since a coal-fired boiler loses 60% of its calorific capacity if firewood is used.
Humanity from the beginning of time to the present has used the burning of dung as fuel. However, it is known that this causes various health problems. WHO estimates suggest that up to 6.5% of the annual disease burden in developing nations is due to the indoor burning of solid fuels (Combustion of dried animal dung as biofuel results in the generation of highly redox active fine particulates, Particle and Fibre Toxicology 2005, 2:6, 4 Oct. 2005).
It is relevant to indicate that the smell produced by the direct burning of dung is a very important factor since it permeates clothes, homes and entire environments, in addition to the obvious environmental problems that this causes.
It is also relevant to point out that the purpose of using the dry products or by-products of the aforementioned processes, in general, only points to the production of solids for burning or power generation. However, ligno-cellulosic material, as a by-product, can also be used as a reactant in processes that do not lead to the destruction of the by-product for power generation, thus being a way of recovering a waste with a higher added value.
In addition to the health problems and costs already described, there are technical problems when using this type of fuel without any prior treatment. In boilers, corrosion of the steel is observed regardless of its origin (normal steel, chrome steel, stainless steel). It is possible to observe a corrosion of 8 mm per year, as indicated in the referred document (http://www.um.edu.uy/docs/6_comportamiento_de_cenizas_y_suimpacto_en_sistem as_de_%20combustion_de_biomasa.pdf Ash Behaviour and its Impact on Biomass Combustion Systems, Report on Scientific and Technical Diffusion Works, no. 10 (2012) 69, ISSN 1510-7450, ISSN (online) 1688-9584).
This problem also occurs with biomass derived from animal fodder, leaves and tree branches, since chlorine is fixed in the leaves, bark and in all fast-growing crops.
The present development corresponds also to a contaminant-free calorific energy product, with minimal or no amounts of silica monitored through the ash, minimum concentrations of nitrogen and odourless. This is therefore a combustible product with high calorific power, but derived from animal waste with high levels of silica and high levels of nitrogen such as manure among others.
Due to the diet of ruminant animals, which feed mainly on grasses, their digestive process uses cellulose and hemicellulose as a source of sugars, leaving lignin as waste, which is indigestible, but with a calorific value of approximately 5500-6500 Kcal/kg. (Studies on the Energy Assessment of Forestry Fuels for the prevention of forest fires in Sierra de la Primavera (Jalisco, Mexico) by means of Combustion calorimetry and Flammability tests, Thesis by Antonio Rodriguez Rivas, University of Compostela, Spain, 2009).
It should be understood that the present development is not limited to the particular methodology, methods, systems, composite products, materials, manufacturing techniques, uses and applications described herein, as these may vary. It should also be understood that the terminology used herein is employed for the sole purpose of describing a particular embodiment, and is not intended to limit the scope and potential of the present development.
It should be noted that the method, system, product and use, here, in the claims and throughout the text that the singular does not exclude the plural, unless the context clearly implies so. So, for example, the reference to a “use or method” is a reference to one or more uses or methods and includes equivalents known to those skilled in the art. Similarly, as another example, a reference to “a step”, “a stage” or “an embodiment” is a reference to one or more steps, steps or embodiments and may include implicit and/or supervening sub-steps, steps or embodiments.
All the conjunctions used must be understood in the least restrictive and most inclusive sense possible. Thus, for example, the conjunction “or” must be understood in its orthodox logical sense, and not as an exclusive “or”, unless the context or the text expressly requires or indicates so. The structures, materials and/or elements described must also be understood to refer to functionally equivalent ones in order to avoid endless exhaustive enumerations.
The expressions used to indicate approximations or conceptualisations must be understood in this way, unless the context mandates a different interpretation.
All names and technical and/or scientific terms used herein have the common meaning given by a common person, qualified in these matters, unless otherwise expressly indicated.
Methods, techniques, elements, compounds, and compositions are described, although similar and/or equivalent methods, techniques, compounds, and compositions to those described may be used or preferred in the practice and/or testing of the present invention.
All patents and other publications are incorporated as references, with the purpose of describing and/or informing about, for example, the methodologies described in said publications, which may be useful in relation to the present development.
These publications are included only for the information they contain prior to the filing date of this patent application.
The following concepts are defined to provide clarity to this development:
Cavitation or vacuum suction: for the present development, the cavitation process is understood as a hydrodynamic effect that occurs when vapour cavities are created within water or any other liquid fluid in which are acting forces that respond to pressure differences, as can happen when the fluid passes at high speed along a sharp edge, producing a decompression of the fluid due to the conservation of Bernoulli's constant. The vapour pressure of the liquid may be reached, such that the molecules that compose it immediately change to the vapour state, forming bubbles or, more correctly, cavities. The bubbles formed travel to areas of higher pressure and implode (the vapour suddenly returns to the liquid state, abruptly “squashing” the bubbles) producing a high-energy gas trail on a solid surface that implodes, cracking it upon impact.
The implosion causes pressure waves that travel through the liquid at speeds close to the speed of sound, regardless of the fluid in which they are created. These can dissipate in the liquid stream or they can impact upon a surface. If the area on which the pressure waves collide is the same, the material tends to weaken structurally and an erosion begins which, in addition to damaging the surface, causes it to become an area of greater pressure loss and therefore a greater centre for the formation of vapour bubbles. If the vapour bubbles are near or in contact with a solid wall when they implode, the forces exerted by the liquid crushing the cavity left by the vapour give rise to very high localised pressures, causing pitting on the solid surface. Note that depending on the composition of the material used, this could lead to oxidation, with the consequent deterioration of the material. (https://en.wikipedia.org/wiki/Cavitation)
Biomass: for the present development, biomass will be understood as the waste products of animal metabolic processes, especially those of cattle and pigs, and other elements used for their diet; it can also be understood as the waste product of a bioreactor, which has a high content of ash (heavy metals, silica, among others), a high nitrogen content, a high sulphur content, among other parameters that will be seen in the application example.
Slurry: the terms “manure”, “slurry” and “dung” are used to refer to livestock faeces. The difference between one and the other is unimportant both for the product and for the method, since it simply lies in the fact that the slurry is collected in a pond or slurry pit and the term manure and dung is more generic, it could have a water content lower than that found in a slurry pit and does not make specific reference to the form of storage.
In any case, the way of collecting and storing the manure does not affect or change the method described or the quality of the solid lignocellulose biofuel obtained from it.
Regulations: refers to compliance with the limit parameters of standard ISO 17225-6, and also to the specific parameters of each of the analyses carried out for this development.
Silica: refers to silicon oxide, sand and its derivatives, generally between 7% to 12% of dry bovine faeces.
Nitrogen: defined, for this development, as all the nitrogenous material that exists in the aforementioned animal waste, formed broadly by urea nitrogen, such as uric acid and ammoniacal nitrogen.
All the concepts and information described in patent application PCT/CL2017/00009 by the same inventor are an integral part of the present development.
The present development corresponds to a method, a system and a product and by-product for synthesis (or intermediate product) that is obtained or can be obtained through the treatment of slurry that allows obtaining the greatest amount of ligno-cellulose as a raw material and/or fuel, the largest amount of cellulosic material as a product for burning and the by-product for synthesis, for both, with a minimum amount of contaminants, a minimum amount of silica related to the ash residue, and a minimum amount of nitrogen. The procedure uses organic waste from livestock, which consists of faeces and urine and/or slurry.
Within the method, it is of the utmost importance to mention in the present development the energy savings based on the use of energetically passive substeps during washing, which will be described below.
The present development also corresponds to a method for the treatment of manure that leads to obtaining a high-quality fuel product that efficiently replaces the use of firewood and coal in boilers, whether for residential or industrial use.
Quality means a high standard of efficiency, through a greater amount of kcal/kg, a lower emission of toxic gases, a lower generation of ash well below the lower limits imposed by standard ISO 17225-6, which indicates between 6% to 10% w/w as combustion ash residue, with a lower production of silica as combustion residue, with a lower existence of nitrogen derivatives, as well as having a low energy consumption production process, harmonious with current environmental standards such as caring for the environment, helping to reduce environmental pollution, decreasing gas emissions, improving the sanitary status of livestock companies, and recycling the liquids and solids involved in the process, reusing them efficiently.
The aforementioned fuel product of the present development is obtained through the treatment of slurry or manure to obtain derivatives with lignin or ligno-cellulose as raw material and/or fuel.
The present process is a continuation of what is described in patent application PCT/CL2017/00009 by the same inventor. Based on patent application PCT/CL2017/00009, where a slurry pit is defined as a pool that collects cattle faeces and urine. Likewise, it can be composed of other elements, such as those present in cattle bedding (straw and sawdust), residues from biodigesters or bioreactors, digestates, pieces of rubber from rubber blankets, rubber, wood shavings, plant husks, such as from rice, chemical products, sand, cattle feed remains, and water, among many others.
It is already known that the process can be carried out through three alternative system feeding paths.
In the first system feeding alternative, the material coming from the (slurry pit or pool (A) that has a capacity range of between 200 m3 and 10,000 m3, preferably 700 m3) is connected through the passage (1) to the common screw conveyor, with a capacity for moving wet solid material (approximately 95% humidity) between 150 and 600,000 kg/h, preferably between 250 and 30,000 kg/h, with a slight filtering of liquid, where the solid remains with between 70% and 85% humidity (D), which can optionally be pre-washed with clean water (L), with a flow rate in the range of between 10 and 1000 litres/min in the step (30), which is inserted through the upper part of the screw. Optionally, in step (6), it can be ground (F) with a hammer mill or simple shredder that leaves the solid with a range of particle sizes between 5 and 20 mm and pass on to step (10) where it enters the washing system (I). If the material is taken directly from the channel that supplies the slurry pit, in a range between 250 to 30,000 kg/h with an average humidity of 70% to 85%, or the material is liquid enough without hard dung, step (7) is chosen and the material goes directly to the washing system (I).
The second alternative for feeding the system through step (2), the Slurry Pump (a) with a flow range of 80 kg/min to 14,000 kg/min, preferably 700 kg/min, preferably 100 kg/min), takes the (slurry from the slurry pit (A)) and impels them through a hose taking them to step (3), which is a traditional liquid and solid separator (C), with a capacity of between 100 to 1000 kg/min, preferably 285 kg/min, is fed by clean water (L) through passage (29), where the clean water (L) comes externally from springs or sources without contaminants. The material that has been separated by the Liquid and Solid Separator (C) can be directed through two independent flows, step (4) and step (5). Step (4) leads directly to the washing system (I), or step (5), taking it to the hammer mill or simple shredder (F), with a grinding capacity of between 25 and 2000 kg/min of solid material, preferably 80 kg/min, preferably 43 kg/min) having eliminated lumps, and through step (10), it reaches the washing system (I).
The third alternative for feeding the system (E) uses the Slurry Pile (E), which corresponds to that formed by waste from the liquid and solid separators from slurry pits and/or biogas plants and/or dung accumulation, optionally passing through step (8) to the hammer mill or simple shredder (F) and taken through step (10) to the washing system (I), or from step (9) directly to the washing system (I).
Any of the three alternatives used allows the material to be taken to the washing system (I), without ruling out other undefined alternatives for the entry of slurry into the washing system (I). Within these other input alternatives could be digestates directly from a biodigester or a bioreactor.
The washing system (I) comprises different associated devices and steps that cooperate with one another. If the slurry pit (A) releases slurry in sufficiently liquid, uniform conditions and without major lumps, the first device is the slurry pump (a), (included in the system because initial impulsion of the slurry is required) with a capacity of impulsion between 80 to 14,000 kg/min, preferably 700 kg/min, preferably 100 kg/min, which pumps or moves the slurry with a humidity in the range between 80% to 95%, preferably between 84% and 90%, with a percentage of dry matter between 9% to 12% w/w from any of the forms of slurry feeding, previously mentioned, to an initial device such as a screen, sieve or rotary filter (b), which can optionally vibrate, with a filter mesh size of 10 US mesh (2 mm) up to 40 US mesh (0.4 mm), preferably 20 US mesh (0.841 mm), which filters and separates a more homogeneous solid product than that provided by the sources of slurry delivery, previously mentioned, with a humidity range from 70% to 90% w/w, preferably 83% w/w. The screen type device refers to a flat mesh optionally vibrating to improve water run-off, positioned in the range of 30° to 60°, preferably at 45°, with a filter mesh size as mentioned above. On the other hand, the sieve type device alternative corresponds to a mesh circumscribed to a frame that can optionally vibrate to better extract the water, arranged at a negative inclination. And finally, the rotating filter type device corresponds to a rotating cylindrical mesh which filters the flow that passes through it. Several of these rotary filters can be arranged in series or in parallel, and be washed with external jets of clean water. Both the shaking and rotary types of filters maintain the same mesh size mentioned above. From the screen, sieve or rotary filter type device (b), the retained solid falls by gravity into a feeder screw device (c), which is a common solids drive screw with a material displacement capacity between 500 to 2000 kg/hr, preferably 1000 kg/hr, with which the solid is moved to feed a dosing device (d) that makes portions and standardises the amount of solid, between 500 kg/h up to 7000 kg/h, preferably 1000 kg/h to enter the next device. In this step, the humidity of the product is between 60% and 35%, preferably 45% w/w. The dosing device (d), for example a basket, screw, rocker, which generally corresponds to a system for regulating the dosage of the material with a required pressure, where for example, it can be a preprogrammed funnel-type bucket that releases its content when it reaches a pre-programmed weight. It mainly consists of an electro-mechanical control system for the dosage and release of the material to be measured. Once the dosing device (d) is filled, it releases its content into the washing and humidification tank (e) through the solids entry point (e2). The washing and humidification tank (e) hydrates and homogenises the previously filtered solid and brings it to a humidity between 85% and 99% by weight, preferably 97% by weight, where said washing and humidification tank (e) comprises: a tank with a capacity between 5 and 100 m3, preferably 35 m3, with an inlet for the washing water (e1), which can be above or below the tank, and through this inlet is optionally injected ozone (O3), and another point of entry of the solid (e2) to be treated. The washing and humidifying tank (e) also includes, in the centre, a tubular paddle agitator device (e3) that, when it rotates, generates a centripetal effect from the rotating movement that sucks the mixture from below the tank into its interior and releases it through the upper part of the tube, where also, on the other hand, the washing water from the first injection (e1) generates a stream that drags the solid, separating it in combination with the previously mentioned centripetal movement effect. Alternatively, the contents of the washing and humidification tank (e) can simply be centrifugally agitated from the centre through paddles with the respective washing water from the first inlet (e1), generating a torrent that drags and separates the solid. After this, if there is excess liquid in the washing and humidification tank (e), it is expelled through the level transfer outlet (e4), in the upper part of the washing and humidification tank (e), transferring the content back to the slurry pit or tank (A). The washing and humidification tank (e) also fulfils the function of homogenising and degassing the excess Ozone (O3), after which and continuing with the process, the transfer of solids is channelled directly from the washing and humidification tank (e) to the cavitation and impingement tanks (g) by means of cavitator pumps (g1) with a flow capacity, per cavitator, between 100 and 3000 L per minute, preferably 800 L per minute per cavitator, with powers between 2 and 50 Kw, preferably and by way of example without wanting to restrict other capacities of the system, 4 Kw/h to be able to process between 400 and 1500 kg/hour of slurry with a range between 85% and 99% humidity on dry basis, preferably 90%, preferably 97%, preferably 98%, preferably 99%, preferably to process 500 kg/h of fibres. To produce the ozone-water mixture, it is prepared in an attached ozone preparation tank (o), where ozone is bubbled through ozone-generating machines (p) into a volume of water (J) between 1000 L/h up to 320,000 L/h, preferably 100 to 14,000 L/min, preferably 1,000 L/min.
The origin of the continuous flow of water (J) is the same as that mentioned in the patent by the same inventor PCT/CL2017/00009, where the water (J) that enters the Washing and humidification tank (e) after passing through the attached ozone preparation tank (o), is driven by the liquid drive pump (N) that enters through step (13) upper inlet, and step (27) lower inlet, which come from the liquid drive pump (N) which is supplied by step (26), coming in turn from the accumulator and purifying tank (J), which is supplied by step (28), and by step (15) that comes from the filtrates of the entire washing system (I). For its part, the purification and accumulation tank for washing water (J) generates a flow that is represented by the step (24) and which feeds the tank with biological material concentrate and inert impurities (G), which will be treated to be left as compost. Likewise, the aforementioned biological material concentrate and inert impurities tank(s) (G) are also fed by the liquid waste generated by the final granulometric filtering (h), the gases bubbled from the cavitation and impingement tank (g) and the hammer mill screw (j), which corresponds to step 14, as can be seen in
The cavitator pumps (g1) are proportional to the number of jets through which the liquid to be treated passes through the cavitation ducts (g2), this means that if the jet passes through a cavitation duct (g2), it must necessarily be driven by a pump or several jets, by a pump of greater power. The cavitation ducts (g2) can operate in series or in parallel, depending on the layout of the system, it can be one or “n” depending on the amount of product to be processed, preferably one cavitation duct, or preferably two cavitation ducts. The cavitation and impingement tank (g) comprises a series of components that will be described below, firstly, it comprises the cavitation duct(s) (g2), as described in
Internally, the cavitation duct (g2) comprises three sections, ordered from the inlet for the waste flow enters to its outlet in the final granulometric filtering (vi). First, the cavitation duct (g2) is fed from the washing and humidification tank (e) passing through the cavitation pump(s) (g1), where these residues enter through the diameter of the inlet duct (g2ad) in the first nozzle section (g2aa) in which the internal diameter of the cavitation duct (g2) is reduced with a nozzle angle of between 15° and 35°, preferably 21°. This reduction in the internal diameter (g2ae) of the cavitation duct (g2) ranges from a slight reduction in the inlet internal diameter of the cavitation duct (g2) to ⅕ of the internal diameter, preferably ⅓. This section has a length between 7 cm and 41 cm, preferably 107 cm, preferably 110 cm. Reducing the diameter of the duct in this section rapidly increases the flow rate of the fluid at a constant inlet pressure.
Following the flow of the residue, next comes the second flow load section (g2ab), which maintains a constant internal diameter in relation to the tapering in the internal diameter of the previous section, where this flow load section (g2ab) comprises a length between 4 and 23 cm, preferably 6 cm, preferably 11 cm. In this section a high flow rate is maintained at a constant pressure.
Continuing with the conduction of the fluid, comes the third and last section of the diffuser (g2ac) where the internal diameter of the cavitation duct (g2) is widened again at an angle between 5° and 10°, preferably 7°, until reaching the same inlet diameter (g2ad) of the cavitation duct (g2), where the length of this section ranges from 22 cm to 124 cm, preferably 33 cm, preferably 49 cm. In this section, the cavitation effect is produced because when the fluid comes with a high flow rate (high speed) and passes through the edge of the angle that is formed when the diameter of the duct expands, a sudden pressure drop is generated, which generates microbubbles in the fluid and their coalescence, managing to agitate the fibres, agglomerates and particles mixed in the fluid, preferably silica particles, preferably waste derived from nitrogen, sulphur derivatives, heavy metal derivatives such as cadmium, mercury, lead among others, and waste fibres. In this section and depending on the differences in the flows (relative velocities of the fluid) formed, the inlet pressure to the cavitation duct (g2) can go from a constant pressure to 25% of that pressure in milliseconds, preferably 50%, by way of example, and without limiting other ranges, from 4 atmospheres to 0 atmospheres of pressure at the outlet of this section. The process carried out in the cavitation duct (g2), does not consume energy and achieves, through a physical process, efficient separation of the fibres, the silica and the rest of the components of the treated waste in order to deliver a pre-processed product to the final granulometric filter (h), so that it, in turn, achieves maximum cleanliness.
Then, and continuing with the flow direction, a second element called the impingement duct (g2b) is connected, which communicates directly with the cavitation duct (g2) and delivers its pre-processed product to the impingement of flows. This impingement duct (g2b) comprises three sections, where the first section maintains the same internal diameter of the inlet (g2ae) to the cavitation duct (g2) and is called the separation section (g2ba), where the flow is partly retained, maintaining a laminar flow and a physical space is provided for the component elements of the waste to be separated. This section comprises a length of 14 cm to 76 cm, preferably 20 cm, preferably 30 cm.
The second section of the impingement duct (g2b), in the direction of the flow, corresponds to the outlet reduction section (g2bb), where the inlet diameter (g2ad) is reduced to a larger diameter (g2bd) with respect to the reduction diameter (g2ae) of the flow load section (g2ab), in the range of between 45% and up to slightly less than the internal diameter of the cavitation duct (g2), preferably by 50%; the length of this section it is between 2 cm and 11 cm, preferably 3 cm, preferably 5 cm. The angle of reduction in this section is of the order of between 25° and 35°, preferably 30°. This section, despite the reduction in the diameter of the duct outlet (g2bd), induces a reduced pressure, so it does not generate greater resistance and additional pressure variations.
Finally, the last section before washing the residue is the outlet section (g2bc), which can be directed and will guide the outlet jet of the residue to the final granulometric filter (h). This section maintains the reduced diameter of the previous section and has a length of between 1 cm and 7 cm, preferably 2 cm, preferably 3 cm.
Inside the cavitation and impingement tank (g) two output jets are made to collide with each other, or an output jet against one of the walls of the tank, or against a sheet or deflector from impingement ducts (g2b), where the direction of the collision between jets is preferably frontal, although it can be angled if there are more than two jets, at a distance of between 1 cm and 200 cm, preferably 2 cm, preferably 10 cm, preferably 50 cm, preferably 100 cm, preferably 150 cm, where the ability to shred the fibres of the jets is indirectly related to the distances between the impingement ducts (g2b), in other words, the smaller the distance, the greater the shredding. To improve the frontal impingement of two jets, an optional part is presented, which makes the two impingement ducts (g2b) face one another, called the steering and impingement tube (g2h), which consists of a tube with the same diameter as the impingement duct outlet (g2b) but with two lateral perforations (g2f) and one lower central perforation (g2g) that fulfil the objective of channelling the explosion of the jet as shown in
Cavitation and flow impingement generate an unexpected effect in the present development, which consists in that externally applied oxidising species such as O2 and O3 react chemically with subspecies derived from nitrogen, sulphur and other pollutants, partly volatilising this nitrogen, sulphur and other contaminants, as volatile elements in combination with oxygen, thus removing part of this contaminant from the end product. In order to eliminate these volatile contaminants, the cavitation and impingement tank (g) also includes a gas outlet duct (g3d) in its upper part that channels and bubbles the gases in the biological material concentrate and inert impurities tank (G) in order to enrich this residue with the dissolved gases generated in the cavitation and impingement tank (g) in step 14.
The cavitation and impingement tank device also includes a product outlet (g3a) from the flow impingement, a handle (g3b) for maintaining the cavitation ducts and a viewer (g3c) for verifying the operation of the device. In general, the product that comes out of the impingement has a humidity in the range between 85% and 99% w/w on a dry basis, preferably 90% w/w, 98% w/w and 99% w/w.
By gravity, the product resulting from the impingement of flows falls and is positioned on the final granulometric filter device (h) that corresponds to a final device such as a screen, sieve or rotary filter (h), which can optionally vibrate, with a filtering mesh size of between 0.25 to 2 mm (10 to 60 US mesh), which filters and separates a more homogeneous and finer solid product than the one delivered by the previously mentioned cavitation and impingement device (g), with a humidity range between 70% and 90%, preferably 83%, where the moistened fibres are retained and the liquid with its respective contaminants is filtered a second time. This device is arranged at an angle that ranges from 10° above the horizontal to 80° above the horizontal, preferably 45°. For this second filtration, the screen, sieve and rotary filter type devices are similar to those described for the first granulometric filter. On the other hand, the solid retained in this final filter can be sprayed with recycled water (J) or clean water (L) before passing to the next device.
Finally, and continuing with the handling of solid products, the solid that falls from the impingement of the flows, mentioned above, is deposited by gravity in the hammer mill screw device (j), where this device is a compact piece of equipment that operates with two elements, firstly, an extruder mill element and secondly, a hammer mill element. The first element of the extruder mill is made up of the following interrelated elements, initially the solid falls by gravity and enters through the inlet hopper (j6), this hopper channels the solid through the screw axis (j1) which moves the solid against the tightening system (j8). The screw axis (j1) in turn consists of a pipe with a continuous helix (j1a) with a rotation angle ranging from 15° to 50°, preferably 20° and with a distance between turns of preferably 15 cm, without wanting to restrict other efficient possibilities with this measure, it also includes two pipe end bushings (j1b), with an internal pipe reinforcement (j1c), all mounted on a shaft (j1d), with a shaft end bushing (j1e). The screw shaft (j1) is also supported in the extruder screw element of the hammer mill screw device (j) by a rear support (j2) and mounted on two conical circular bearings (j3) to maintain the movement of the screw shaft (j1), these bearings are fastened to prevent their exit following the line of the axis, by the fastening sleeves (j5), in parallel an o-ring (j4) separates these bearings (j3) from the incoming material in the input hopper (j6).
The solid, moving through the screw axis (j1), before reaching the tightening system (j8), passes through a sieve device (j7), this sieve device (j7) includes the circular sieve itself (j7a) with between 80 and 1000 slides, preferably 112, with measurements, by way of non-limiting example, of 400 mm long, 30 mm wide and 2.5 mm thick, with a mesh size of between 0.05 and 3 mm, supported on a sieve support (j7c) and wrapped in the sieve casing (j7b), which fulfil the function of channeling the water extracted in the tightening and channeling it through the drain (j7f) to be recirculated, retaining the solid in the inner surface of the screening device (j7). This sieve device (j7) is easily removable by means of the sieve handle (j7e) for cleaning, where in addition to extracting the sieve itself (j7a), the device cover (j7d) can be removed.
The previously mentioned tightening system (j8) comprises an area delimited by the covers: upper (j22), upper side (j23) and lower side (j20) that support the accumulation of solid material chopped by means of the blades (j8e) that are tightened on the blade holder (j8a), which in turn is stabilised on the horizontal axis by the spring (j8c), which in turn exerts pressure against the direction of the material via the screw axis (j1). The tightening system to hold onto the extruder mill element of the hammer mill screw device (j), is mounted through a lever-holder (j8b) that holds the lever (j8d), which holds the tightening system (j8) to the entire device in an easy and removable way in case the blades (j8e) need replacing. This tightening system (j8) remains in a firm position without rotating, but allows the screw shaft (j1) to rotate freely, causing the retained solid to be squeezed, increasing the draining time, leaving a more dehydrated solid material.
On the other hand, the tightening system (j8) compresses and shreds the solids and when they partially accumulate on the screw shaft (j1) they release liquid in the sieve device (j7). Most of the solids, however, fall due to pressure and gravity to the grinding unit (j14) or to a traditional hammer mill that corresponds to the second element of the hammer mill screw device (j), where this grinding unit (j14) is made up of a support box (j14c) and a circular output of solid material (j14b), internally it comprises a set of grinding or shredding blades in the shape of a symmetrical cross (j14a) mounted on a tube (j14i), which rotates on a square grinding shaft (j14h), where for this rotation, the grinding shaft (j14h) is positioned between two square base bearings (j14d) at each end of the tube outside the box. The blades rotate due to the energy delivered during the rotation of the pinion (j14f) and due to the pressure exerted by the solid trying to come out due to the restriction generated by a grid (j14g) with a mesh size slightly greater than the thickness of the blade. In order for the grinding assembly to be in position and to rotate freely on its shaft, it also contains a bearing for the grinding assembly support (j14e), which is mounted on the grinding assembly support (j17).
Continuing with the extruder mill element, on the screw axis (j1), after the tightening system (j8), comes the bearing (j9) and the main support (j16) that supports most of the hammer mill screw device (j). Continuing with the same arrangement, comes the pinion area, delimited by the upper cover (j19) and the side covers (j21), this area protects the set of large (j10) and (j11) small pinions mounted on the shaft (j1d), where the large pinion (j10) provides the mechanical energy to the grinding unit (j14). After this comes the reducer motor (j12) that delivers power to the entire hammer mill screw device (j). This motor is directly associated via the standard motor shaft (j13) to the shaft Old) to deliver rotation to the entire device, with a speed between 10 to 250 rpm. By way of example, this motor can have a capacity of 10 Hp and a speed of 140 rpm, without limiting the capacity and power of the motor to this specific example. On the other hand, the motor is supported on the motor base (j18) and is positioned by the motor support (j15).
The efficiency of the hammer mill screw device (j) is such that it begins working with solids with moisture around 85% w/w and after all the milling, pressing, shredding and filtering processes it reaches a mixture of fibres with a humidity under 30% w/w, which results in lower energy consumption in later steps for efficient drying of the end product. Also, the size of the final fibre is in the range of 0.595-0.297 mm, taking into account 72% of the total sample, which provides a greater surface area for exposure to oxidants and fire in the final combustion of the product, thus improving the efficiency of the final combustion.
Once the by-product leaves the hammer mill screw device (j), it continues with the steps and equipment similar to those mentioned in the previously mentioned patent application by the same inventors.
The solid material is transported through step (16) to the pressing or centrifuging section (O), which eliminates excess water from the material, which is subsequently taken through step (18) which corresponds to a dryer (P), which is fed with hot air through the passage (21) which in turn is fed by the Boiler (Q), then this material falls through the passage (19) onto a dry magnetic vibrating screening device (S) that corresponds to a sieve-type device, similar to the one indicated in step (b) of the washing system (I) but dry, with magnetic bars to trap metals and a sifting mesh size of between 2 mm (10 US mesh) up to 0.595 mm (30 US mesh), which sifts and separates a fine homogeneous powder-type solid product with a moisture range of between 10% and 5%, preferably 7%, where the fragments of larger size and the sieved powder are channeled through pneumatic ducts (20) to the pelletizing process (T). This device is arranged at an angle ranging from 10° above the horizontal to 80° above the horizontal, preferably 45°.
The material that has been processed is incorporated into the Pelletizing process (T) through step (20) to finally form pellets and/or ligno-cellulose briquettes and/or some other solid form to be burned.
The present development, in addition to cleaning all kinds of impurities from the outside of the fibre, is also capable of cleaning the fibre on the inside, which is full of bacteria, enzymes, gastric juices that are responsible for dissolving cellulose and hemicellulose to transform them into sugars, but when they leave the animal they remain inside the fibre as contaminants and when burned they emit odours and gases that are harmful to health.
The present development is also capable of cleaning the inside and outside of the fibre of silica residues, thus improving the end product by eliminating its ability to vitrify inside boilers and stoves.
To describe the process in the washing system (I) of the present development, eight sub-steps are included, such as: initial and final granulometric filtering, dosing, centripetal or centrifugal movement, water turbulence, optional ozone, cavitation, impingement and hammer mill screw dehydration, continuing with the steps already known in the state of the art, to achieve a double objective, minimum energy consumption in the process by having sub-steps with processes without energy so consumption and an end product of high energy power with a minimum of contaminants, especially nitrogen and ash, among others. This system, through granulometric filtering, centripetal or centrifugal movement, water entrainment, optional ozone, cavitation, impingement and mechanical dehydration, manages to release all contaminants both inside and outside the solid components of the slurry and its mixtures, in a continuous process eliminating its contaminants, leaving a solid product with particular characteristics. As previously mentioned, the application of chemical agents is not an option for the present development.
The modifications made to the washing system (I) and its substeps in the total performance of the system are a fundamental part of this development.
The sub-steps of the washing system process (I) include:
Specifying, the power necessary for the cavitation and impingement step (v) is a cavitation pump power (g1) in a range from 2 Kw to 50 Kw, preferably and by way of example without wanting to limit other capacities of the system, a power of 4 Kw to be able to process 1200 kg/h of slurry at 80% humidity or higher, leaving the diluted fibre in the range of 0.5% to 5%, preferably 2%, preferably 2.5%, preferably 3%, in water, which is the ideal medium for the cavitation step, with flow rates of, for example, 500 L/min passing through the cavitator tube (g2). As previously mentioned, the fluid to be treated is required to have a predetermined humidity and dilution to be able to operate in the cavitator tube (g2), where within these parameters the ideal is a humidity of 97% and a particle size no greater than 20 mm.
After passing through the cavitation comes the separation and lamination of the flow where the flow is slowed down and its pressure is stabilised. Once the flow is stabilised and laminated, it is released by making the flows collide against each other, this means that if there are only two jets they collide in opposite directions, adding their speed; if there are more than two jets, these collisions are in pairs or in trios neutralising the projection outside by the cavitation and impingement tanks (g).
Another specification is that, to extract the cellulosic fibres and lignin with its derivatives, and as the final part of the washing process, step (vii) uses the hammer mill screw device (j). This screw is also a desiccator screw because it manages not only to move the fibres to the subsequent drying steps, but also to extract the water from the mixture from 98% to 30% w/w (the state of the art generally mentions that screws, in general, leave between 70% to 80% of moisture in the mixture), which saves time and energy when drying the fibres in later steps.
This screw can be used in other drying or moisture reduction processes regardless of the method and field of application of the present development.
To achieve these effects, the hammer mill screw device (j) operates at a high speed of between 20 rpm up to 200 rpm, preferably 140 rpm, preferably 70 rpm, in a small diameter and with internal fibre-breaking blades, as mentioned earlier in their description.
The particle size coming out of the hammer mill screw device (j) is in a low range of 0.595-0.149 mm.
With respect to the end product obtained as pellets or briquettes for burning, according to Table I it comprises:
0-0.2
0-0.5
This figure describes a diagram with the steps of the present development and how they are partly related to steps of the previous state of the art.
This figure presents only a diagram of the component elements of the washing system (I). Where they are indicated according to their numbering:
This figure shows the cavitation and impingement tank (g), its cavitation duct (g2a), the relationship of its internal components, between the cavitation and laminar flow duct (g2a) and the impingement duct (g2b) and its different parts. The numbers indicate:
This figure shows the angle of collision of the jets coming out of two impingement ducts (g2b) and how they behave when they leave the device.
This figure shows the hammer mill screw device (j), showing all its parts and pieces, where the numbers indicate:
This example was developed in the slurry pits of the Las Garzas agricultural laboratory.
On Aug. 17, 2020, 5450 kg of mainly bovine slurry were used and the procedure of the present development was applied. The cleaning water used comes from a well in the area, with water with a high content of dissolved salts.
Slurry and manure samples were taken initially, delivering the following summary of analytical results, as shown in Table II:
After passing the slurry through this process, the final pellet of the same was also sampled, delivering the following analytical results, according to Table III:
For the comparative calculation of the reduction of Silicon, it should be taken into account that the percentage of Silicon varies fundamentally in relation to the percentage of Ash, and the latter with respect to the total product.
The following processes were used for the analyses under international standard conditions as shown in Table IV:
The following Table VIII shows the analyses performed on the reactants and products of the patent application by the same inventor PCT/CL2017/00009.
Particle size was measured under standard EN 15149-1, by the transfer of particles through different sieves and the weight of the material retained in each one for the product that was being measured, in order to calculate the majority percentage retention for a range of particle sizes.
The measurement of lignin, cellulose and hemicellulose was carried out based on standard ASTM D-1106.
As can be seen by comparing the results of Tables II and Ill, the step of the washing system achieves toxicity parameters (referring to the chemical elements that can produce risks) that are much lower than those already known, also, in the final pellet silica, particle size and nitrogen levels are achieved that are extremely lower than those of origin.
Regarding the process, apart from having more efficient steps with respect to washing the fibre and the end product, energy consumption is unusually lower compared to the state of the art with respect to particle size. This is due to the use of energetically passive steps for the fibre washing process. This can be verified comparatively in the following Table V:
As can be seen, the decrease in energy by the new development is verified as 59%, with a 40% decrease in the percentage of water in the end product obtained.
When analysing the result above, we consider that the cavitation and subsequent impingement steps are passive steps of lower energy consumption with respect to the ultrasound indicated in the state of the art. On the other hand, the hammer mill screw dehydration step is highly efficient in dehydrating the fibres, leading to a lower energy consumption in the dryer. The product can be compared before the dryer operation of application PCT/CL2017/00009, where the humidity range was between 65% to 75% w/w; on the other hand, the current humidity range handled before the dryer is in the range of 30% to 35% w/w. If you add to this a smaller average particle size range for the current product, it results in almost 71% less energy consumption by the dryer.
On the other hand, to verify the energy efficiency of the hammer mill screw (j) of this process, the efficiency of the device with respect to its energy consumption was verified, as seen in Table VI:
Table VI shows the great convenience of using the hammer mill screw, because the state of the art discloses, in general, screws that obtain 75% humidity in the end product at a power of 1 kW for every 100 kg of dry matter, which means that 300 litres of water have to be evaporated with an caloric energy cost of 224 kW to obtain the dry matter. The high efficiency hammer mill screw (j) achieves a range of between 30% and 35% moisture in the material with 5.12 kW of power per 100 kg of product at equivalent dry matter and with a quantity of 43 litres of water to evaporate which is equivalent to 36 kW of heat energy. This means that the high efficiency hammer mill screw (j) in this case obtains a caloric energy saving of 184.12 kW.
Finally, a comparative chemical analysis of the pellets produced by the process closest to the state of the art (PCT/CL2017/00009) and the pellets produced by the present development was carried out, as can be seen in the following Table VII:
Based on the results shown above, we show below in Table I the ranges for higher calorific value, lower calorific value, total humidity and relevant toxic compounds expected from the product generated by the method of the present development:
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0-0.5
Where (w/w %) corresponds to percentage in dry weight.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CL2020/050112 | 10/2/2020 | WO |
