Briquetting of lignocellulose biomass torrefects to produce an environmentally friendly fuel

Abstract

Briquetting of lignocellulosic biomass torrified into an environmentally friendly fuel, characterized in that the structure of the chemical-physical biomass requires devices whose characteristics meet the requirement taking into account the lowest energy expenditure and gentle environmental impact.

Description

[0001] The use of fossil fuels for power and heat generation is an unavoidable and harmful evil due to the emissions they produce, such as carbon dioxide (CO2), which urgently need to be replaced by environmentally neutral fuels. Wood pellets and, to a lesser extent, wood briquettes belong to this category. These are products of the life processes of woody plants (trees and shrubs), a natural, heterogeneous colloidal system containing many components, including chemical compounds. Specifically, they contain carbon, oxygen, hydrogen, minerals, and trace elements. These form the structural substance consisting of hemicellulose, cellulose, and lignin, which is modified using a variety of methods, mostly excluding hemicellulose, and used as the base material for pellet production. 01. Briquette base material

[0002] The briquette base material consists solely of residual materials from paper or construction timber processing and their residues, such as sawdust, which, after preparation (drying and particle size distribution), are agglomerated primarily using piston rod presses, die presses (hydraulic or mechanical) and screw presses to a volume of up to 1 / 20 of the bulk volume of the wood residues. 02. Briquette quality:

[0003] The quality characteristics of the wood residues to be processed are an important component of the certification program for wood briquettes according to DIN EN ISO 17225-3 (May 2023 edition), detailing their chemical and physical properties. These include briquette dimensions, surface finish, moisture and ash content, calorific value, and other factors. 06. Briquette production - Dust:

[0004] Briquette production, using dried sawdust with a moisture content of less than 10% by weight, is subject to the risk of developing an explosive mixture. The residual dust from this mixture, which invariably settles on machinery and equipment, is highly contaminated. Safety precautions for this type of explosion and its prevention are defined by ATEX Directives 2014 / 34 / EU and 1999 / 92. 07. Briquette production - Exhaust gases:

[0005] The specific designs of extruder presses guarantee briquettes with physical properties that exceed those of DIN ISO 17225-3. For comparison: base material sawdust, grain size 2-6 mm, moisture content before and after extrusion 8% / 4%, strength after extrusion 200 kg / m³ 3 - 1400 kg / m 3 Calorific value 20.44 MJ / kg

[0006] Exhaust gases, i.e., condensed water vapor, are a product of the excessive frictional heat generated by the process and the residual moisture and capillary water content of approximately 28% remaining in the raw material after drying. These exhaust gases escape unprotected from the extruder into the surrounding environment, leading to an increase in pollutants such as CO2 and VOCs (volatile organic compounds). They contaminate the environment and cause health problems for the workers in this area.

[0007] Energy balance: (Disadvantage) The enthalpy of vaporization lost with the exhaust gases, amounting to 2,257 kJ / kg, remains (lost) and is not taken into account for the production process. 08. Briquette production - Cooling:

[0008] The briquette raw material is extruded into a continuous strand with a diameter of approximately 90 mm and transported in an open, approximately 30 m long pipe system connected to the extruder. It is cooled to approximately 30 °C, elongated to 300 mm, and stored. A disadvantage of this method is that the energy loss resulting from cooling and the accompanying contaminated exhaust gases negatively impact the energy balance of the production process. 9. Briquette production for an environmentally friendly product:

[0009] To recognize briquettes as an environmentally friendly fuel, like wood pellets, a complete departure from existing processes is necessary. High energy consumption and increased emissions of harmful substances are unacceptable. Technically reliable measures are needed to gain acceptance for briquettes as an environmentally friendly fuel. New environmentally friendly briquettes - an invention with new technical measures: 01. Torrefication:

[0010] Torrefaction of biomass is used to drive off water and oxygen-containing compounds with low calorific value, such as carbon monoxide and organic acids. The highly corrosive acetic acid in the hemicellulose portion of the biomass reacts at elevated temperatures of 140°–180°C, is released from the biomass structure, and thus promotes positive chemical changes for the subsequent torefaction process. 2. Technological challenge:

[0011] The chosen method of so-called dry torrefaction, carried out in an oxygen-free atmosphere, ensures the controlled modification of the chemical and physical components of the briquettes pre-made from biomass. The reactor designed for this type, with its novel technical characteristics, is a new development and does not represent the state of the art. It is necessary to create an atmosphere suitable for torrefaction, which, through the enrichment of nitrogen (N2) or carbon dioxide (CO2), imparts important physical properties such as density (kg / m³). 3 ), compressive strength before torrefaction improved from 2.75 MPa to 5.0 MPa and calorific value (MJ / kg). 03. Torrefaction Process Flow:

[0012] Heating gas temperature range 100 °C - 300 °C, adjustable starting from the temperature of the extruded briquettes leaving the press, which is approximately 150 °C. This temperature is held for approximately 5 minutes, then increased to 200 °C, held for another 5 minutes, then increased to 250 °C, and after another 5 minutes, increased to a maximum of 270 °C - 280 °C and held for a further 5 minutes. Process time sequence: 5 + 5 + 5 + 5 = 20 minutes, which may require minor adjustments depending on the briquette's base material. Torrefaction plant - a new product with technical features

[0013] The reactor intended for briquette refining is part of a concept designed to eliminate the negative side effects, particularly energy waste and environmental pollution, of the existing manufacturing process. The operating facilities required for this type of process represent a previously unknown innovation, comprising the following components: 01. Main features of the facility: length Width Height 3 pieces 45' High-Cube ISO Containers, dimensions (mm): 13.710 x 2.440 x 2.900 Equipment - Container I

[0014] Designed for the installation of either one or two briquette presses, with a capacity of approximately 2,650 kg / h, complete with all necessary equipment. Advantages of this type include protection against dust and noise, which are disruptive with conventional presses. Special equipment required: insulated container, temperature control, air circulation, slatted or smooth floor, LED lighting, double door, and emergency release, among others. Reactor - Container II:

[0015] Attachments: 4 identical conveyor belts, 2 briquette lifting platforms, 2 briquette distributors, 4 adjustable drives, roof mounted. Insulation: Building material class: DIN 4102, A2 non-combustible, bulk density 400 kg / m³ 3 Thickness 16 / 21 mm, W / mK at 300 °C = 0.086, Inner lining: Material material no. 1.4301 Reactor briquette torefaction 2,650 kg / h, linked with Rector C and its complete control system Reactor - Container III:

[0016] Reactor complete with: cooling and hot air circulation, cooling unit, rotary heat exchanger (energy recovery), evaporator, condenser, compressor, fittings, control system: spark detection, torrefaction process,

[0017] Condensate drainage. Pressure and oxygen control (inerting / purging) of the percentage of nitrogen or oxygen.

[0018] Carbon dioxide content of the atmosphere set in the reactor according to valid ATEX guidelines. Important requirements: 1. The condensed water vapor generated by the extrusion process must be introduced into Container II via the shortest possible route. 2. The extrusion press outlet must be adjusted to the level of the intended inlet opening of the reactor container. 02. Briquette production disadvantages:

[0019] The extrusion press forms the raw material into briquettes. The frictional forces generated in this process lead to a significant temperature increase in the raw material. After drying, this temperature, combined with the remaining residual moisture, including the capillary moisture content in the wood (approximately 28% by weight), drastically alters the chemical and physical structure, consisting of hemicellulose, lignin, and cellulose. Hemicellulose reacts between 140° and 160°C and is expelled as a highly corrosive liquid. This also includes CO, CO2, and furfural, all of which are components of the condensed water vapor. This vapor, released during the manufacturing process in the press's working environment, poses a health risk and dissipates with considerable energy loss. Exceptions prove the rule. Process disadvantages: 1. Harmful burdens on health and the environment 2. Significant energy losses of chemical substances and their latent heat potential (water 2,257 (kJ / kg)) 03. Advantages of Reactor II and III Briquette Production:

[0020] The aforementioned process disadvantages have been eliminated. There is no environmental pollution, no energy waste, and a reduction in harmful emissions (volatile substances, noise, and particulate matter). These types of controls are achieved through the use of reactor systems I-III and the continuous torrefaction process. Starting with the extrusion press installed in reactor I, the extruded briquettes are conveyed directly into reactor II. There, positioned on a conveyor belt, they transfer their latent heat to the circulating hot air. They then pass through the hot air zone in a 20-minute cycle, are torrefied, and transferred from the hot air zone to the cooling zone. There, they are placed on an identical conveyor belt, cooled, and finally evacuated from the reactor at a temperature of 30°C. Literature - References: 1. Knowledge Storage Wood Technology Fundamentals, VEB Fachbuchverlag Leipzig 1988, 2nd edition Materials - Raw Material Wood Pages 10 - 58 see page 29. - 1.1.4.1. Wood Moisture Table 1 / 12 2. Dubbel Handbook of Mechanical Engineering, 19th edition 1997, editors W. Beitz and KHGrote, pages D. Thermodynamics, Stephan, Stuttgart, pages D 25 - 10. Heat transfer - D 39: M Climate. M - 58 Regenerator (energy recovery) 3. Textbook of Chemical Process Engineering by a team of authors, 2nd revised edition, VEB Deutscher Verlag für Grundstoffindustrie Leipzig 1969, page 551 Kinetics 6.4.6. Kinetics of heterogeneous catalysis, pages 551-560 4. HÜTTE, Taschenbuch der Werkstofftechnik, 4th edition, Verlag von Wilhelm Ernst & Sohn, Berlin 1967, page 194, M, Reaction kinetics in homogeneous systems, M 1 - M 5, N. Reaction kinetics in heterogeneous systems, page 200- 201, O. Catalysis, O1 Homogeneous, O2 Heterogeneous (contact, surface) catalysis. 5. Andreas Ohliger, Dissertation, Experimental and thermal investigations of the torrefaction of beech wood, submitted to RWTH Aachen, 13.05.2015 6. DIN-Plus, Certification program for wood briquettes according to DIN EN ISO 17225-3 (as of May 2023) SECTOR No. D.9.8 Production of solid torrefied fuels - Fundamentals, quality, properties 7. DGUV Explosion Document 213-06, DGUV Information 8. DFG - NOAEL: Communication 59: MAK and BAT Values ​​List 2023 9. German Social Accident Insurance Institution for the Raw Materials Sector: ATEX Directive 2014 / 34 / EC, 3rd edition, May 2023 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] ATEX Directives 2014 / 34 EU and ATEX 1999 / 92

[0004] Speicher Holztechnik Grundlagen, VEB Fachbuchverlag Leipzig 1988, 2nd edition Materials - Raw material wood pages 10 - 58 see page 29. - 1.1.4

[0020] Dubbel Pocketbook for Mechanical Engineering, 19th edition 1997, editors W. Beitz and KHGrote, pages D. Thermodynamics, Stephan, Stuttgart, pages D 25 - 10

[0020] Leipzig 1969, page 551 Kinetics 6.4.6. Kinetics of heterogeneous catalysis, pages 551 - 560

[0020] HÜTTE, Taschenbuch der Werkstofftechnik, 4th edition, Verlag von Wilhelm Ernst & Sohn, Berlin 1967, page 194

[0020] M, Reaction kinetics in homogeneous systems, M 1 - M 5, N. Reaction kinetics in heterogeneous systems, pages 200- 201, O. Catalysis, O1 Homogeneous, O2 Heterogeneous (contact, surface) catalysis

[0020] Andreas Ohliger, Dissertation, Experimental and thermal investigations of the torrefaction of beech wood, submitted to RWTH Aachen, 13.05.2015

[0020] DIN-Plus, Certification program for wood briquettes according to DIN EN ISO 17225-3 (as of May 2023) SECTOR No. D.9.8 Production of solid torrefied fuels - Fundamentals, quality, properties 7. DGUV Explosion Document 213 - 06, DGUV - Information

[0020]

Claims

[1] Briquetting of lignocellulosic biomass torrified to produce an environmentally friendly fuel, characterized by , that the structure of the chemical-physical biomass requires devices whose characteristics meet the requirement while taking into account the lowest energy expenditure and gentle environmental impact. [2] Briquetting according to claim 1, characterized by This type of requirement, with mobile units distributed across three 45' IOS containers, fulfills the briquetting process. This is based on the installed briquetting presses, whose exhaust gases are directly routed into Container II during briquetting. [3] Briquetting according to claims 1 and 2, characterized by that the heat generated by briquetting and, in particular, the contaminated exhaust gases can be effectively absorbed by the hot air irradiation system without significant losses. [4] Briquetting according to claim 1, 2 and 3, characterized by, that the energy contribution resulting from briquetting is ensured by the use of rotary heat exchangers, ensuring optimal energy recovery and, in particular, adsorbing environmentally hazardous substances (VOCs) from the ambient air. [5] Briquetting according to claim 1, 2, 3 and 4, characterized by that the energy recovery significantly reduces the energy expenditure of the hot air irradiation for the torrefaction of the briquettes placed on the conveyor belt. [6] Briquetting according to claim 1, 2, 3, 4 and 5, characterized by that torrefaction can be carried out in an inert atmosphere of the reactor that has been cleaned of recirculated air. [7] Briquetting according to claim 1, 2, 3, 4, 5, and 6, characterized by , that after torrefaction, the briquettes ready for cooling are placed at the level of the conveyor belt in the upper half of the reactor using the lifting device stationed at the end of the conveyor belt. [8] Briquetting according to claim 1, 2, 3, 4, 5, 6, and 7, characterized by , that the briquettes are cooled from ~270°C, the max. torrefaction temperature, to the predetermined storage temperature of ~30°C. [9] Briquetting according to claim 1, 2, 3, 4, 5, 6, 7 and 8, characterized by , that the air is cooled with a surface cooler operated with water at 6°-12°C and that the latent energy obtained from the hot air v.~ 270°C provides hot water at a temperature of ~ 80°C for operational use. [10] Briquetting according to claim 1, 2, 3, 4, 5, 6, 7, 8 and 9, characterized by that this type makes a crucial contribution to an improved energy balance in briquetting and at the same time prevents the volatile contaminated exhaust gases produced in the open briquette cooling system from causing harm to the workforce and the environment. [11] Briquetting according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, characterized by , that through torrefaction the characteristics of the chemical-physical modification are advantageous to the agglomerated, i.e. briquetted, biomass cooled to ~30 °C from the reactor, so that the characteristics of the described protective claims, such as the hydrophobic (water-repellent) properties, do not require packaging made of plastic film or similar for further shipping and thus contribute to a significant environmental improvement.