Bioenergy installations. Biogas technology. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Alternative energy sources

 Comments on the article

Fermentation, which is the basis of biogas production, results in final products: methane CH₄ (55 - 65%), carbon dioxide CO₂ (30 - 35%), hydrogen H₂ (3 - 5%), in a small amount of hydrogen sulfide and ammonia. Essentially, fermentation combines three biological processes: hydrolysis, sour and methane fermentation.

The output of biogas from straw manure is approximately 1 - 1,8 m / day per head of cattle.

Biogas has an average calorific value of 20 - 23 MJm3.

Along with biogas, anaerobic digestion of livestock and poultry waste produces a valuable environmentally friendly fertilizer, devoid of pathogenic microflora, helminth eggs, weed seeds, nitrites and nitrates, and specific fecal odors.

The potential for biogas production using animal waste, poultry farming and processing enterprises of the agro-industrial complex is very high.

Production of biogas from municipal solid waste (MSW)

The sharp increase in consumption in recent decades around the world has led to a significant increase in the generation of municipal solid waste (MSW). One of the main methods of MSW disposal all over the world remains burial in the near-surface geological environment. Under these conditions, the waste undergoes intense biochemical decomposition, which in particular causes the generation of landfill gas (LFG). SG emissions entering the natural environment form negative effects of both local and global nature. For this reason, in many developed countries of the world, special measures are being taken to minimize SG emissions. This actually led to the emergence of an independent branch of the world industry, which includes the extraction and utilization of landfill gas.

The main method for solving this problem is the technology of extraction and utilization of SG. For the extraction of landfill gas at landfills, the following schematic diagram is used: a network of vertical gas drainage wells is connected by gas pipeline lines, in which the compressor unit creates a vacuum necessary for transporting SG to the place of use (Fig. 5.2). Installations for collection and disposal are mounted on a specially prepared site outside the landfill body.

Fig.5.2. Block diagram of a plant for the production and utilization of biogas

Vertical wells are used to extract SG at MSW landfills. Usually they are located evenly over the territory of the dump body with a step of 50 - 100 m between adjacent wells. Their diameter fluctuates in the range of 200 - 600 mm, and the depth is determined by the thickness of the dump body and can be several tens of meters. For drilling wells, both conventional drilling equipment and specialized equipment are used, which make it possible to construct large-diameter wells. At the same time, the choice of this or that equipment is determined by economic reasons.

Each well drains a specific solid waste block, conditionally having the shape of a cylinder. The stability of the well operation can be ensured if its flow rate does not exceed the volume of the newly formed SG. The assessment of the gas productivity of the existing strata of MSW is carried out in the course of preliminary field gas geochemical studies.

The construction of a gas drainage system can be carried out both on the entire territory of the solid waste landfill after the end of its operation, and on individual sections of the landfill in accordance with the sequence of their loading. At the same time, it should be taken into account that landfill bodies with a thickness of at least 10 m are suitable for the extraction of SG. It is also desirable that the territory of the solid waste landfill, where the construction of the SG collection system is planned, be reclaimed, i.e. covered with a soil layer of at least 30 - 40 cm.

On average, gas generation ends in a dump body within 10 - 50 years, while the specific gas output is 120 - 200 cubic meters. m per ton of MSW. A significant variation in gas productivity and process speed is determined by the environmental conditions prevailing in a particular landfill body. Among the parameters controlling bioconversion are humidity, temperature, pH, composition of organic fractions.

Production of biogas from sewage waste (WWW)

For more than 20 years, Western European countries have been actively involved in the practical solution of the problem of waste disposal from wastewater treatment plants.

One of the common waste disposal technologies is their use in agriculture as fertilizers. Its share in the total amount of WWS ranges from 10% in Greece to 58% in France, averaging 36,5%. Despite the popularization of this type of waste disposal, it is losing its appeal, as farmers fear the accumulation of harmful substances in the fields. Currently, in a number of countries the use of waste in agriculture is prohibited, for example, in the Netherlands since 1995.

Incineration of waste water treatment ranks third in terms of waste disposal (10,8%). In accordance with the forecast in the future, its share will increase to 40%, despite the relative high cost of this method. Incineration of sludge in boilers will solve the environmental problem associated with its storage, obtain additional energy during its combustion, and consequently reduce the need for fuel and energy resources and investments. It is advisable to use semi-liquid waste to generate energy at thermal power plants as an additive to fossil fuels, such as coal.

There are two most common Western technologies for incineration of waste water treatment:

• separate combustion (combustion in a liquid fluidized bed (FLB) and multi-stage furnaces);
• co-firing (in existing coal-fired CHP plants or in cement and asphalt plants).

Among the methods of separate combustion, the use of liquid layer technology is popular; Such technologies make it possible to ensure stable combustion of fuel with a high content of mineral components, as well as to reduce the content of sulfur oxides in flue gases by binding them to limestone or alkaline earth metals contained in the fuel ash during combustion.

Environmental aspects of the use of waste water treatment

Comparison of the chemical compositions of WWS, black and brown coals burned at the CHPP shows that the elemental compositions of WWS and brown coal differ insignificantly. WWS (6,2% moisture) contains less carbon by 24,5% than hard coal (12% moisture) and 5% less than brown coal (39% moisture). The proportion of sulfur exceeds its specific gravity in coal by only 0,2% compared with coal and by 0,4% compared with brown. The nitrogen content in WWS is comparable to that of hard coal and is 2% higher than that of brown coal. Comparison by dry matter shows that the carbon content in WS is almost 30% less, sulfur and nitrogen almost does not change.

The chemical composition and characteristics of WWS ash make it possible to use it as a building road material (with a particle diameter of more than 1 mm), as well as an additive to cement or on dumps as a filler.

Possible options for waste disposal

There are six alternative options for the disposal of sewage sludge, based both on new non-traditional technologies developed on the basis of Russian or European experience and not having practical use, and on completed "turnkey" technologies:

1. Incineration in a cyclone furnace based on drum drying furnaces of treatment facilities (Russian technology - "Techenergokhimprom", Berdsk);
2. Incineration in a cyclone furnace based on drum boilers of treatment facilities (Russian technology - "Sibtekhenergo", Novosibirsk and "Biyskenergomash", Barnaul);
3. Separate combustion in a new type of multi-stage furnace (Western technology - "NESA", Belgium);
4. Separate combustion in a new type of fluidized bed furnace (western technology - "Segher" Belgium);
5. Separate combustion in a new cyclone furnace (western technology - firms "Steinmuller", Germany);
6. Co-firing in an existing coal-fired CHP plant.

Obtaining biogas from the waste of poultry farms and livestock farms

Renewable biomass resources of various origins are accumulated annually in large volumes or are used inefficiently.

Efficient use of biomass is possible with the introduction of appropriate technologies and equipment for the production of fuel in the form of wood chips, briquettes, gas and liquid fuels.

The accumulated experimental materials of the review speak in favor of the wide use of biomass:

• biomass ranks 4th in the world among various types of fuel;
• biomass accounts for 14% of primary fuel and energy resources, and in developing countries - up to 35%;
• biomass is more environmentally friendly when used as a fuel - less emissions of sulfur compounds and CO levels₂ in the atmosphere;
• the payback period of power plants operating on biomass does not exceed 2 - 4 years.

However, some research work is currently underway on the direct combustion of biomass and its anaerobic digestion.

Obtaining biogas from forestry and agricultural waste

To maximize the use of forestry and agricultural waste in the energy sector, a decomposition process has been developed, which consists in high-speed heating without oxygen (air) access to temperatures at which the rate of release of the required products is maximum. It is designed to solve energy and environmental problems.

The parameters of the fast pyrolysis process, the composition and the amount of released products are preliminarily specified for each type of raw material. The installation is developed for each type of raw material. The maximum processing temperatures are determined by the temperature of existence of the substance in the condensed phase.

High-speed heating of the substance provides: minimal energy loss to the environment; the maximum speed of the chemical process with the release of products into the gas phase; maximum concentration of moisture and its use. The rate of heating of the substance must exceed the rate of physicochemical processes occurring in the processed mass. The yield of liquid fuel is 70% of the organic mass of the raw material. For example, 1 liters of liquid fuel can be obtained from 700 ton of sawdust.

Inorganic components and products of chemical modification (coal-like residue) remain in the solid phase. The amount of carbon-like residue is determined by the lignin content and is always lower than the amount of residue obtained from other processing methods.

To obtain the main component of liquid fuel, the gas phase is condensed (low molecular weight products formed in the process are not condensed). The gas phase, after condensation or without it, can be sent directly to incineration. The heat of combustion (calorific value) of the main component of the fuel is usually greater than the calorific value of dry fuel of this type. So the calorific value of wood is 4500 kcal / kg, and the heat of combustion of liquid fuel is 5500 kcal / kg. Liquid fuel can be used as motor fuel in internal combustion engines.

The installation is powered by electricity or by burning processed products or raw materials.

Advantages of the process: high speed, high degree of conversion of processed products; small dimensions of the main unit of the installation; low energy consumption per unit of processed products; low cost of energy obtained from the reaction products.

The cost of the installation with a capacity of 2 tons of processed raw materials per day is 2,5 million rubles. When processing sawdust from 2 tons, 1,4 tons of liquid fuel are obtained. The annual output is 500 tons of liquid fuel, at a price of 0,1 USD/liter, the annual turnover is 50 thousand USD. The payback period is 3 years.

Author: Magomedov A.M.

See other articles Section Alternative energy sources.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Alcohol content of warm beer 07.05.2024

Beer, as one of the most common alcoholic drinks, has its own unique taste, which can change depending on the temperature of consumption. A new study by an international team of scientists has found that beer temperature has a significant impact on the perception of alcoholic taste. The study, led by materials scientist Lei Jiang, found that at different temperatures, ethanol and water molecules form different types of clusters, which affects the perception of alcoholic taste. At low temperatures, more pyramid-like clusters form, which reduces the pungency of the "ethanol" taste and makes the drink taste less alcoholic. On the contrary, as the temperature increases, the clusters become more chain-like, resulting in a more pronounced alcoholic taste. This explains why the taste of some alcoholic drinks, such as baijiu, can change depending on temperature. The data obtained opens up new prospects for beverage manufacturers, ... >>

Major risk factor for gambling addiction 07.05.2024

Computer games are becoming an increasingly popular form of entertainment among teenagers, but the associated risk of gaming addiction remains a significant problem. American scientists conducted a study to determine the main factors contributing to this addiction and offer recommendations for its prevention. Over the course of six years, 385 teenagers were followed to find out what factors may predispose them to gambling addiction. The results showed that 90% of study participants were not at risk of addiction, while 10% became gambling addicts. It turned out that the key factor in the onset of gambling addiction is a low level of prosocial behavior. Teenagers with a low level of prosocial behavior do not show interest in the help and support of others, which can lead to a loss of contact with the real world and a deepening dependence on virtual reality offered by computer games. Based on these results, scientists ... >>

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Random news from the Archive Xiaomi Walkie-Talkie 3 13.04.2022 Xiaomi has released a third-generation right called the Xiaomi Walkie-Talkie 3, which is on sale in China for $62, offering several improved features including full Netcom 4G support. Netcom's full 4G support extends to the top three carriers in China. This feature allows you to establish communication at a distance of up to 5000 km throughout the country. The walkie-talkie has different functions and supports over-the-air updates at the same time, which may add more functions in the future. Xiaomi Walkie-Talkie 3 supports various intercom methods, including face-to-face intercom, multi-person communication, and two-way voice calls. The walkie-talkie is equipped with a high-performance audio system, consisting of a large-sized 40mm speaker and a professional sound processing chip, which provides a 30% increase in volume compared to previous models. There is also an environmental noise reduction algorithm that reduces distortion by 10,9%. Xiaomi Walkie-Talkie 3 has a built-in 3000mAh battery that can last up to 100 hours of standby time and can also be used up to 60 hours. The device is charged via USB-C. The novelty is equipped with a 2-inch color screen, meets the degree of protection IP54 and is equipped with a built-in rear clip. There is a 3,5 mm jack and the ability to connect to Bluetooth headsets.

Other interesting news:

▪ Growing stem cells on the ISS

▪ Skipping breakfast is dangerous for the heart

▪ Laser disc up to 1 TB

▪ Earth's technosphere weighs 30 trillion tons

▪ Laser lens for electrons

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Palindromes. Article selection

▪ article Anesthesiology and resuscitation. Lecture notes

▪ article Where money is made from plastic instead of paper? Detailed answer

▪ article I pumped up the mattress, laced it up - a boat. Tourist tips

▪ doorphone intercom article (ENGLISH). Encyclopedia of radio electronics and electrical engineering

▪ article Square on the calendar. Focus Secret

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024