Comprehensive calculation analysis of the use of biogas as fuel for the "Invest" steam boiler

Abstract

The work determines the change in the heat balance and calculates the gross emissions of major pollutants when switching from natural gas to biogas. The methodology includes a numerical analysis of the heat balance and the calculation of emissions based on the fuel composition and annual consumption. It is established that the transition to biogas (composed of ~60% CH4 and ~37% CO2) leads to a decrease in boiler efficiency by 4-5%. This decrease is explained by the high CO2 content, which prevents complete combustion and leads to chemical underburning (q3) at the level of ~5%. The calculation of gross emissions with annual biogas consumption showed significant emissions. Biogas is an important renewable alternative, however, its direct use in existing equipment is associated with significant trade-offs between environmental friendliness (reduction of the greenhouse effect from methane) and operational efficiency and local emissions. The main component of biogas is a combustible gas, i.e. methane, which releases energy during combustion. Biogas has a high methane content, depending on the fermentation process and the materials used. Modern energy needs are met mainly by three types of resources: organic fuels, water and nuclear energy. The energy of water and nuclear energy is used after conversion into electrical energy. At the same time, a significant part of the energy contained in organic fuels is used as heat; only a part is converted into electricity. However, in both cases, the release of energy from organic fuels is associated with its combustion and, thus, with the emission of combustion products into the environment. The combustion of solid fuels and fuel oil releases into the atmosphere ash components containing unburned fuel particles, sulfur dioxide and sulfur trioxide, nitrogen oxides, vanadium compounds, sodium salts, a certain amount of fluorinated compounds and gaseous products of incomplete combustion. Ash sometimes contains not only non-toxic components, but also more harmful pollutants. Thermal power plants are currently responsible for approximately 20% of the total emissions of hazardous industrial waste into the atmosphere. The main advantage of biogas production is the use of renewable energy sources. The constant availability of a wide range of organic substances ensures continuous and sustainable biogas production, thereby contributing to the conservation of fossil fuels. Biogas plants mainly use animal manure and renewable raw materials. However, biogenic waste from the agricultural and food industries, as well as household waste, is playing an increasingly important role in biogas production. This allows the use of previously unused primary raw materials that have been an environmental burden. These organic substances are used alone or in combination (as co-substrates) with other organic substances. This allows the development of site-specific programs that promote the efficient production and use of biogas.