U1 Thermochemical & Biochemical processes with biomass.pptx

Los procesos físicos de la biomasa son métodos mecánicos o térmicos que preparan, acondicionan o transforman la biomasa sin alterar su composición química. Su objetivo principal es mejorar el manejo, transporte y eficiencia energética del material.

1. U1 Thermochemical & Biochemical processes with biomass

2. PHYSICAL: Mechanical alteration of the physical characteristics of the material. THERMO-CHEMICALS: Thermal decomposition of biomass. BIO-CHEMICALS: Biochemical decomposition of biomass by the development of microorganisms

3. Introduction In the energy context, the term biomass is used to refer to a renewable energy source based on the use of organic matter formed by biological means in the immediate past or the products derived from it.

4. CONVERSION PROCESSES APPLIED TO BIOMASS FOR ITS ENERGY USE Conversión t e r m o - q u í m i c a Conversión b i o - qu í m i c a BIOMASA C o m bu s t i b l es d e b i o m a s a C a l o r y vapor Electricidad C o m b u s t i ón directa F u e r z a motriz

5. * Dry biomass It is one that can be obtained naturally with a humidity content of less than 60%, such as firewood, straw, etc. This type is best presented when used energetically through Thermochemical or Physicochemical processes, which produce thermal energy or secondary products in the form of solid fuels.

6. * Thermochemical processes Thermochemical processes are those that transform biomass, under certain pressure and temperature conditions, to obtain solid, liquid or gaseous products, generally through exothermic reactions. These products will be different depending on the type of technique applied. Taking into account the amount of oxygen involved in the transformation, they are classified as:

7. 1) Combustion It is a treatment at a temperature between 150 ° C and 1,200 ° C, in which the amount of oxygen is greater than the stoichiometric, that is, it is above the needs determined in a theoretical chemical reaction. The biomass is completely oxidized, and hot gases are obtained, which is the part that is used as thermal energy. Colloquially, we will say that we burn biomass .

8. It allows to obtain thermal energy, either for domestic (cooking, heating) or industrial uses (process heat, steam through a boiler, etc.). The technologies cover a wide spectrum that goes from the simplest (an open fire stove) to high-performance boilers in the industry .

9. 2) Gasification Treatment where oxygen is involved in the chemical reaction, but in an amount lower than the stoichiometric, which significantly reduces the obtaining of solids compared to the previous process. As a result, a gas called lean gas is obtained that is used as fuel .

10. It consists of burning biomass (forest residues) in the presence of oxygen, in a controlled way, in order to produce a fuel gas called "lean gas" due to its low calorific content in relation to, for example, natural gas. The gasification is carried out in a closed container, known as a gas generator, in which the fuel is introduced, as well as a smaller quantity of air than would normally be required.

11. 3) Pirolysis Treatment at a temperature between 500 ° C and 600 ° C, and in the absence of oxygen. It is based on the decomposition of organic matter by heat. As a result, a mixture is obtained which is partly solid (mainly coal), partly liquid, and partly gaseous. Liquids and gases are hydrocarbons and aliphatic compounds.

12. Pyrolysis generally results in charcoal, with liquids and gases being considered by-products of the process. Charcoal as a solid fuel represents the advantage over the biomass that gave it origin, of having a higher calorific value or, what is the same, a lower weight for the same amount of energy, which allows easier transport

13. 4) Liquefaction Process that includes a series of phases used to convert a gas into a liquid state. The processes are used for scientific, industrial and commercial purposes. Many of the gases can be put into liquid state at normal atmospheric pressure by simple cooling and others, such as carbon dioxide, require pressurization. Liquefaction of gases is a complicated process that uses different compressions and expansions to high pressures and very low temperatures, using, for example, turboexpansors .

14. Gas liquefaction is used for the analysis of the fundamental properties of gas molecules (intermolecular forces), for the storage of gases, for example: GLP, and in cooling and air conditioning. In these, the liquefied gas inside the capacitor, releases the vaporization heat, and evaporates into the evaporator, where the vaporing heat is absorbed. Ammonia was the first of these refrigerants but has been replaced by oil-derived compounds and halogens.

15. The complete process at the end consists of the change of the gas state to the liquid state by increasing the pressure

16. * Wet biomass This is the type of biomass that has or exceeds 60% humidity, and that, in addition, is especially suitable for treatment through chemical processes and in some special cases, through physical processes, resulting in liquid and gaseous fuels.

17. Biochemical processes The biochemical processes for transforming biomass into energy are those that are carried out by various types of microorganisms , whether they are contained in the original biomass or added during the process . These microorganisms cause the degradation of the complex molecules that make up biomass to simpler compounds with high energy density .

18. These procedures are used , fundamentally , to treat natural or residual biomass with a high moisture content that , if treated by thermochemical methods , would give particularly unfavorable energy yields , due to the high heat of vaporization of water .

19. 1) Anaerobic digestion Also called biomethanization or biogas production , it is a biological process , which takes place in the absence of oxygen , in which part of the organic matter of the excrement is transformed , by the action of microorganisms , into a mixture of gases ( biogas ), consisting mainly of methane and carbon dioxide .

20. Complex process in which different groups of microorganisms intervene . Organic matter decomposes into simpler compounds , which are transformed into volatile fatty acids , which are the main intermediates and modulators of the process . These acids are consumed by methanogenic microorganisms that produce methane and carbon dioxide . All these processes take place simultaneously in the reactor.

21. Benefits Reduces the concentration of organic matter . Reduces bad odors from droppings . Reduces the solid content . It reduces the content of pathogenic microorganisms ( especially if it is carried out at 55º C, that is , in a thermophilic regime ). The fraction of nitrogen in ammonia form increases .

22. Advantages Production of energy if the biogas produced is used . Positive energy balance. Partial stabilization of organic matter . Partial mineralization of organic matter ( carbon and nitrogen ) Control and reduction of bad listeners . Reduction of uncontrolled greenhouse gas emissions . Improvement of the efficacy of other treatment processes to those that can be subjected to the excretions after passing through anaerobic digestion , such as concentration / evaporation or stripping (drag) of ammonia .

23. 2) Alcoholic fermentation Alcoholic fermentation is a bioreaction that allows the degradation of sugars into alcohol and carbon dioxide . The conversion is represented by the equation :

24. The main responsible for this transformation are yeasts . Saccharomyces cerevisiae is the most frequently used yeast species . Of course there are studies to produce alcohol with other fungi and bacteria, such as Zymomonas mobilis , but exploitation at an industrial level is minimal .

25. Alcoholic fermentation is an anaerobic process that , in addition to generating ethanol , releases large amounts of carbon dioxide (CO2) as well as energy for the metabolism of anaerobic bacteria and yeasts .