Problems of various recycling methods .3
Executive summary 3
Field investigation ..5
Most countries need to solve the issue of waste disposal. Currently the bulk of waste dumped at landfills. This situation has extremely negative impact on the environment, since the decomposition of organic substances are released into the atmosphere large quantities of methane, a greenhouse gas many times more potent than carbon dioxide. According to researches many scientists still have not found the optimal solution for the safe and cost-effective waste management. Waste disposal and waste incineration do irreparable harm to human health and the environment, and existing processing methods are not always economically viable (Bernedo, Ferraro, Price, 2014). Even when using highly purified modern waste incineration equipment allocated toxic dioxins and furans, which are harmful to ten times higher than that from the gases by burning coal so this paper proposes the use of plasma gasification plants.
Problems of various recycling methods
Disposal conventional combustion method can not be regarded as a worthy alternative, since practically is extremely difficult to achieve the level of emissions of harmful substances within the prescribed standards (Kinnaman, 2006). The most serious problem is the pollution of groundwater. Rainwater seeping through the municipal solid waste landfill, dissolves in itself toxic substances present in the debris. These may be salts of iron, lead, zinc and other metals from rusting cans, used batteries, rechargeable batteries, a variety of household appliances. The most advanced and promising technology of recycling today is plasma gasification. The essence of this technology is that the waste is subjected to heat processing at very high temperatures and intense ultraviolet radiation, which allows all the organic component converted into a combustible gas, consisting of simple components, the combustion of which do not generate hazardous high-molecular compounds. The gas used to produce electricity. A small portion of electricity provides internal the needs of the plant, the rest can be supplied to the national grid, “it is estimated that producing a new aluminum can from recycled aluminum saves 95% of the energy” (Miller, 2006, p.16).
Availability of automated sorting line ensures effective separation of the components of the waste suitable for re-use, such as metals, glass, plastic. Using of plasma gasification installations that allow safe processing various forms of waste (including toxic) by expanding them to the molecular level. This project is an autonomous, energy independent platform, equipped with automated electronic control systems, and built on a closed circuit, eliminating any emission into the atmosphere. Since the working area is sealed and its temperature exceeds the temperature of decomposition of dioxins, there is no risk of emission of toxic gases.
The only emission is residual heat from the unit. The closed loop is provided by the substitution process of combustion gases on the catalytic oxidation processes, effectively sealing the working areas of the installation by creating a permanent slight negative pressure inside the system, isolation of the feedstock and obtained products.
The main advantage of this technology is the fact that the inorganic component of the waste after-treatment plasma solidifies as environmentally friendly a very durable material. This material can be used in construction and other industries. Thus the technology of plasma gasification is practically wasteless because there are no more than two percent of the mass of waste involved in the process. Admission debris, preparation and storage of fuel carried out in the building. Inside the slight negative pressure is maintained, which prevents the spread of odors. The ventilation system draws air from point garbage reception, equipment for the preparation of fuel and fuel from wet storage compartment and throws it into the air through the system dry and the carbon filter.
All components manufactured equipment designed and perfected to the smallest detail. The conveyor belt is used with the highest strength characteristics. All hardware components are designed and specially selected for critical operating conditions, in a large dust, mud, freezing temperatures, and other negative factors.
The process consists of the following steps:
1. Preparation of waste
All waste is unloaded at an unloading site for the primary sort. Taking into account the fluctuations in the volume of supply, waste collection point is calculated to accommodate debris more than necessary on day 1 of the plant, while still a place for the passage of transport, loading the waste to the plant.
Rubbish sorted by size into three streams.
Stream 1. Fragments comprise less than 15 mm. This flow does not require additional processing.
Stream 2. Fragments of 15 - 80 mm, suitable in size for the process, but they should be sorted. Secondary raw materials (glass, metals, plastics and solid) is automatically removed from the stream, and there are residues of high organic content.
Stream 3 contains large debris from which the same is separated recyclables. What is left, shredded into fragments of not more than 80 mm. Thereafter flows are joined and sent to the wet fuel store.
2. Production of synthesis gas.
The process consists of two closely related, but separate undergoing processes waste gasification and plasma conversion. The prepared waste is fed into the gasifier under strictly controlled conditions, which are supported by adjusting the ratio of fuel, oxygen and steam. The escaping gas contains significant amounts of high molecular weight hydrocarbons, which condense in the form of tars and residues.
"Dirty" synthesis gas from the gasifier is fed into the plasma converter. In the center of the plasma converter generates a plasma arc. Near the plasma arc is achieved the temperature is above 5000 K, at a temperature such intense ultraviolet any molecular compound constituted organic compounds split into partial components: hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2) and water (H2O) . At a sufficiently low level of oxygen supply to the gasification process,
the proportion of H2 and CO combustible components may be high enough to provide a large calorific value of the resulting synthesis gas.
2.2. Gas cooling system
The plasma converter syngas supplied via a refractory lined channel into the cooling system. For cooling gas ≈1200 ° C and ≈200 ° C applied steam boiler generating steam at a pressure of 10 bar, which is used for drying and gasification phases.
2.3. Dry cleaning system
Gas cleaning system, operating at a temperature of 180-220 ° C, removes fine particulate matter from a gas stream, neutralizes the acidic component and removes volatile vapors of heavy metals.
2.4. Wet cleaning system
The synthesis gas is fed into the chamber, where the temperature is reduced using water spray. Then, in a washing compartment, passing through a double filter, the gas subjected to the action of organic solution which absorbs the hydrogen sulfide.
3. Energy production
3.1. Gas turbines
Depending on the desired characteristics of the plant, a certain number of set of gas turbines, and the amount of harmful emissions effectively controlled combustion control process, as well as catalysts and oxidizing system.
3.2. Clean emissions
Afterburning of combustion products implies a thermal oxidizer. This ensures that all the emissions from the process comply with the directive on waste incineration.
The thermal oxidizer is adjusted so that it remains in hot standby at all times when operating equipment. This ensures that in the event of an emergency production stop, the atmosphere will not fall unburned gases.
3.3. Heat recovery
The heat produced from synthetic gas cooling system, is used for generating steam, much of which goes to the internal needs of the plant (drying of waste supply to the gasifier). The remaining pairs can be supplied external to the consumer.
The described process is used by more than 100 companies around the world. This technology is able to process, without harm to the environment, all, including the dangerous types of waste: medical waste, waste chemical and metallurgical industries and the like.
According to rough estimates the construction of a waste processing plant capacity will lead to a significant reduction of greenhouse gas emissions in CO2 equivalent. This value includes:
• Reducing methane emissions emitted in the decay of organic waste in landfills;
• Reduction of CO2 emissions and other carbon compounds that have formed as a result of the production of the corresponding quantity of electricity by thermal power plants.
Plasma gasification is the most environmentally friendly solution to waste disposal problems today. In addition, excess electricity can be considered waste treatment plant as a complete power plant, which can smoothly supply electricity to the grid.
Plasma gasification technology provides an almost complete recycling by providing the least impact on the environment compared with other technologies. The project will reduce the number of landfills, and thus reduce the amount of methane emissions to the atmosphere, as well as contamination of soil and groundwater.
2. The financial and economic aspect
Making a profit from the activity of the plant can vary depending on the type of recyclable waste and the state legislation. Evaluation of investment attractiveness of the project is carried out for each case of alleged placing of the plant. The main sources of these profits were:
3. Waste Disposal.
Fees for disposal of medical waste and other types of hazardous waste is generally much higher than tariffs for processing household waste, so the enterprise profits can be increased by increasing the share of hazardous waste. Communities can work with shop owners and local authorities, to prevent the occurrence in the community of those substances that cause problems for the placement or health in the first place. Civil society organizations can put pressure on governments to adopt laws that force the company to take responsibility for the waste they create. • Supply of electricity to the national network. In many countries there are government programs supporting facilities producing Energy consumption from renewable sources. Therefore, the profit of the electric power supply can be higher than that of traditional fuel stations.
Artificial materials obtained in the process of recycling is completely inert, to the same has unique physical characteristics. This makes it possible to find a use in various industries, such as construction. For example synthetic gasoline has a better quality compared with the traditional due to the fact that the octane number it is achieved due to the greater proportion of branched and cyclic hydrocarbons with correctly oriented hydrocarbon bonds rather than aromatics, as in a conventional gasoline, which sharply reduces specific fuel consumption and gives a considerably lower thermal load on the internal combustion engine, substantially increasing the life.
Using the energy component is one of the promising areas of waste that produces energy, not using natural fuel resources, that is, there is an economy of natural resources. The project involves the construction and commissioning of the production of energy resources and other goods from municipal waste into marketable products with a full cycle of processing and the provision of services for the full utilization, lack of manufacturing waste and autonomous energy supply. The population will be much more willing to sort their waste, choosing items that can be reused or recycled, if they will not have to pay for them so “the persistence of an effect also suggests the presence of longer-lived adjustments to either habits or capital stock in the home” (Bernedo, Ferraro, Price, 2014, p.442). Therefore it is very important that the introduction of fees for the amount of waste was accompanied by an active environmental education and careful supervision. Thus, the analysis of mineral properties in terms of resource potential reveals the following components:
The potential of secondary raw materials, the number of conditional items and materials that can be extracted from the mixture of the waste used.
Energy potential-combustible materials that can be extracted from a waste mixture and used directly as a fuel and as a raw material for fuel.
The biological potential of the waste is the number of substances that may be involved in the process of biodegradable waste with a transition to a qualitatively new state (compost, biogas).
It remains problematic stage and construction of the facility producing electricity. New town planning laws are relatively recent, its implementation requires the adoption of a number of regulations that are not yet available. There should be a system in which the start-up of the complex is possible only after the determination of the causes of the problem and electronic unlocking the central control room. This reduces the likelihood of errors in the management and violations related to improper maintenance, so the likelihood of the following errors in the work is reduced to a minimum.
It is also possible to add to the charter of the company's existing new activities: the production and sale of electricity. As for the producers of "green" energy tax benefits, be sure to arrange an independent legal entity, which will be engaged in the sale of electricity (Carlson, 2001). This simplifies the procedure of calculation of income resulting from the production of "green" energy and simplify the tax benefits. “The field of „green technology” encompasses a continuously evolving group of methods and materials, from techniques for generating energy to non-toxic cleaning products” (Yusof el al., 2014, p.115). In the absence of their own land necessary to lease land for the construction of generating plants, to issue the purpose of the land and the ownership of generation capacity. Professionally drafted a feasibility study accompanied by the development of high-quality project documentation. Investing time and money at this stage will help to properly assess the economic feasibility of the project and its profitability. Certainly such modern enterprises cannot solve the root of the problem of solid waste, but they can significantly reduce the amount of waste, to extend the life of existing landfills and to reduce the negative impact on nature. But there is a real opportunity for humanity to significantly reduce their number and reduce the risk of ecological disaster.
Open burning of waste without proper control can be a source of air pollution. During the combustion of materials of many highly toxic substances formed. So, if before the cause of the greatest number of poisonings in fires, carbon monoxide was mainly formed during the combustion of wooden objects, the recent sharp increase in the number of fatal poisoning gaseous combustion products of synthetic materials. Waste disposal contribute to the emergence of epidemiological risks associated with the appearance of rodents and the transfer of various diseases. As the dumps occur and gradually take the "green" zone and suburban destinations. This, in turn, requires an increase in the cost of transporting waste and contributes to the further contamination of areas with exhaust gases of vehicles.
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