These methods of thermal processing of drilling waste are used to destroy or produce a hydrocarbon component. The methods are effective in removing organic constituents of waste, reduce mobility and the volume of inorganic constituents - minerals and salts. Wastes with an overestimated content of petroleum products (from 10% to 40%), such as oil sludge or hydrocarbon-based drilling fluids, are excellent candidates for thermal processing of waste.An intermediate link to reduce the volume and toxicity of waste and prepare them for future processing or disposal may be thermal processing. It can also be used as the final process of processing into a solid inert phase and, in some cases, in water and petroleum products. There are both stationary thermal processing plants, and mobile[1-2].
Technologies of thermal processing are divided into two groups. The first group includes combustion processes (in cement, hearth, drum furnaces), they completely oxidize hydrocarbons in the presence of air at a very high
temperature. Often, incineration is used to destroy domestic and certain types of industrial waste. The incinerators (waste incineration plants) are very widespread and do not require significant alteration for the disposal of oil-containing drilling wastes. The second group includes the processes of thermal desorption, in which, through an intermediary or directly, heat is supplied to waste to destroy volatile and partially volatile components from a solid base. In some solutions, waste gases condense and separate from water, to extract hydrocarbons, in others they are simply burned. Burning. In this technology waste is incinerated at temperatures of 1200 - 1500 °, thereby reducing the volume and danger of the product of processing. Usually, incineration is used for the processing of flammable, highly toxic or medically dangerous organic substances. The efficiency of the method is achieved with increasing temperature. To achieve complete destruction of organic matter, the residence time of waste in the combustion chamber can vary. When the disposal of waste is unacceptable and other technologies for processing drilling wastes are not available, simple incineration is used in such cases. The most acceptable solution becomes an incinerator, it is installed nearby, for burning other types of waste. All operated incinerators are equipped with facilities that remove particulate emissions and control emissions of nitrogen and sulfuric oxidants. In addition, often many incinerators are equipped with heat recovery units.As a result, when burning watered fuels, smoke decreases due to a deficit of oxygen in the reaction zone.
As in foreign and domestic practice, the method of thermal neutralization of oil sludge is most widely used: This method allows to neutralize the following types of oily waste:
The wastes resulting from wastewater treatment are oily sediments and liquid oil wastes from treatment plants; oil sludge formed during the cleaning of reservoirs and process equipment; oiled soils;
Oil sludge, which is a complex multi-component disperse systems, formed as a result of product pipeline pumping or formed over time in barns;products from the purging of dust collectors, oil separators and separators, characterized by a fairly uniform composition and a high content of hydrocarbons, as well as used compressor and industrial oils.
Thermal method allows together with oil sludge burn contaminated filters, oiled rags, solid household waste. The resulting secondary waste is classified as a 4 hazard class and is subject to exportation to landfills. One of the promising areas of thermal neutralization of solid oil-containing wastes is the use of the principle of "fluidized bed". In the furnaces of the "fluidized bed", the change in the kinetic energy of the transporting gas stream occurs as a result of overcoming the resistance of the gas distribution grid and the material layer (sand), which passes from a calm state to a "boiling" state. On furnaces with a "boiling" layer, it is easier to control the pollution of the environment from harmful substances in oily waste.
The main advantages of the method for burning oil-containing waste in furnaces of various types and designs are:
- significant reduction in the amount of waste;
- economically acceptable;
- the volume of ash formed is 10 times lower than the initial product;
- high efficiency of neutralization;
- heat recovery is possible.
As negative factors of using this method are high energy inputs for additional fuel (gas, oil); requires more capital investment in facilities for cleaning and neutralizing flue gas 1.
Another technological method of thermal processing of oil sludge is pyrolysis, carried out at 500-550? C, in which flammable gases and a solid residue are obtained. This process is recommended for the processing of solid oil sludges with low humidity (no more than 1-3%). It is most economically acceptable, since it allows the organic part of the waste not to be converted to toxic combustion products, but used as an additional fuel for incineration of waste.
One of the varieties of the thermal method is drying in dryers of various designs. The positive aspects of this method are the preservation of valuable components; volume reduction by 2-3 times; possibility of combining
- Cavers, S., Navarro, C., and Lowe, A. J.. Chloroplast DNA phylogeography reveals colonization history of a Neotropical tree, Cedrela odorata L., in Mesoamerica. Molecular Ecology, 12,2003, pp 1451-1460.
- Cavers, S., Navarro, C., and Lowe, A. J. A combination of molecular markers (cpDNA, PCR-RFLP, AFLP) identifies evolutionarily significant units in Cedrela odorata L. (Meliaceae) in Costa Rica. Conservation Genetics, 4, 2004, pp 571-580.
- Cavers, S., Degen, B., Caron, H., Hardy, O., Lemes, M., and Gribel, R. Optimal sampling strategy for estimation of spatial genetic structure in tree populations. Heredity, 95, 2005, pp 281-289.