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19UDC 581.5
RATIONAL USE OF WATER RESOURCES IN THE OIL INDUSTRY
SHAMS NIZAMI GIZI ALIZADE
Master Student of Department of Petrochemical Technology and Industrial Ecology, Azerbaijan State Oil and Industry University, Azadliq Avenue 20, Baku' Azerbaijan
Summary. Rational use of natural resources obtained as a result of mining, especially water resources, play an important role in the implementation of complex measures to protect the environment. Water affects most segments of the oil industry, and therefore efficient water management plays a key role in oil and gas exploitation. The water to be managed is produced together with hydrocarbons and is formed as a by-product of oil and gas refining. The system of objective control over emissions and discharges of pollutants in the industry is not sufficiently formed. One of the main environmental risk factors for the health of the population ofpetrochemical and oil refining areas is the discharge of wastewater into the seas, lakes and rivers. This article discusses promising ways for the development of the petrochemical and oil refining industries and the development of comprehensive programs, taking into account the socio-economic living conditions of the population.
Keywords: oil refinery, wastewater, coagulation, sewage system
УДК 581.5
РАЦИОНАЛЬНОЕ ИСПОЛЬЗОВАНИЕ ВОДНЫХ РЕСУРСОВ В НЕФТЯНОЙ
ПРОМЫШЛЕННОСТИ
ШАМС НИЗАМИ КЫЗЫ АЛИЗАДЕ
Магистрант кафедры нефтехимической технологии и промышленной экологии Азербайджанского Государственного Университета Нефти и Промышленности,
Баку, Азербайджан
Резюме. Рациональное использование природных ресурсов, полученных в результате добычи полезных ископаемых, особенно водных ресурсов, играют важную роль при проведении комплекс мероприятий по охране окружающей среды. Вода влияет на большинство сегментов нефтяной промышленности, поэтому эффективное управление водными ресурсами играет ключевую роль в добыче нефти и газа. Управляемая вода добывается вместе с углеводородами и образуется как побочный продукт переработки нефти и газа. Система объективного контроля за выбросами и сбросами загрязняющих веществ в промышленности сформирована недостаточно. Одним из основных экологических факторов риска влияющих на здоровье населения нефтехимических и нефтеперерабатывающих районов является сброс сточных вод в моря, озера и реки. В данной статье рассматриваются перспективные пути развития нефтехимической и нефтеперерабатывающей промышленности и разработка комплексных мероприятий с учетом социально-экономических условий жизни населения.
Ключевые слова: нефтеперерабатывающий завод, сточные воды, коагуляция, канализация
Oil refineries are the largest consumers of fuel and energy resources, including boiler and furnace fuel, heat and electricity. The efficiency and rationality of their use in the oil refining process is largely determined by the efficiency of the plant's process equipment. Waters used in oil field operations can be broadly divided into two groups: natural water and wastewater. Rivers, lakes,
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coastal waters, groundwater and produced water are the main sources of natural water. Important issues related to natural water include the availability, availability, suitability and injection capacity of water. Wastewater is generated during drilling, completion and extraction of hydrocarbons from groundwater reservoirs. The formation, quality, quantity, sustainability and composition of wastewater are important issues [7].
Layer water is the largest waste stream generated in the oil and gas industry. It is a mixture of various organic and inorganic compounds. Due to the increase in waste worldwide in the current decade, the consequences and impact of the discharge of produced water on the environment have recently become an important issue of environmental concern. Layer water is conventionally treated by various physical, chemical and biological methods during the operation of oil and gas fields. Compact, physical and chemical systems are used during the operation of oil and gas wells on offshore platforms due to space constraints. However, existing technologies are unable to remove small suspended oil particles and dissolved elements.
Biological primary treatment of oily wastewater in onshore facilities can be an economical and environmentally friendly method. Since high salt concentrations and changes in incoming properties have a direct effect on the turbidity of the effluent, it is advisable to include a physical purifier, such as a membrane, to treat the final effluent. For these reasons, future research efforts may focus on optimizing current technologies and using physico-chemical or biological treatment of produced water to meet reuse and discharge limits. On the other hand, due to the formation of large volumes of produced water, many countries with oil fields, as well as countries with water problems in general, are increasingly focusing on efforts to find effective and cost-effective treatment methods to eliminate pollutants [9].
The amount of water in the secondary water supply system of oil refineries exceeds the amount of wastewater by 10-20 times. 25-30 mg / l of petroleum products, 25 mg / l of dependent substances, 500 mg / l of sulfates, 300 mg / l of chlorides in circulating water, the temporary hardness of carbonate should not exceed 5 mg / l.
Wastewater contains petroleum products and dependent substances, phenols, chlorides, surfactants, sulfides, benzene, toluene, etc. It happens that they are filled with storm currents both in the main technological processes and in individual petrochemical plants, pumping stations, tank farms, oil loading plants, washing facilities from the area.
Petroleum products can be in different states in water - easily separated (insoluble), difficult to separate (colloidal) and soluble. In most cases, it is not possible to apply the same disposal for the extraction of all types of oils and petroleum products.
Oil refinery the following fundamental solutions form the basis of the water utilization scheme of the plant without discharging wastewater into the strata: local treatment of the most polluted wastewater (sulphide-containing technological condensates, sulfide-alkali with tetraethyl lead, wastewater with coke hydroxide). and so on.); grouping of wastewater according to discharge systems, taking into account the characteristics of pollution; Separate wastewater treatment with drainage systems and their reuse [6].
Oil refineries have two main industrial sewage systems. The first sewage system receives neutral industrial and industrial rainwater from most process facilities, pumps and tanks, containing no more than 2 g / l of mineral salts, about 3 g / l of petroleum products and 100-300 mg / l of dependent substances. washing of oil products, washing of floors. Currently, two schemes are used in local enterprises for wastewater treatment of the first system. The first includes cleaning of oil traps, ponds, flotation tanks, sand filters, etc., and the treated water is used to feed the circulating systems. The second, more promising scheme includes mechanical and physico-chemical treatment plants, as well as biological treatment and sometimes wastewater treatment plants [1].
Emulsion-mineralized wastewater containing about 5 g/l of petroleum products, 300-500 mg/l of suspended solids, as well as salts, reagents and other organic and inorganic substances is discharged
into the second system. Depending on the type and concentration of pollutants, the secondary sewage system includes a number of independent networks:
- oil waters of oil refineries, bottom waters of raw material parks, washing racks, washing and evaporation stations;
- condensed sulfur-alkaline waters, condensates formed from alkalinization of oil products;
- Wastewater from the production of synthetic fatty acids (FFA) containing organic acids, paraffin and other substances;
- Sewage of petrochemical industry (ethylene, propylene, butyl alcohols);
- acid wastewater contaminated with mineral acids and salts [2].
Wastewater from the second sewage system undergoes mechanical and physical-chemical treatment of sulfur-alkaline wastewater, as well as two-stage biological treatment. Devices can be used for heat treatment of brine wastewater, condensate is returned to production and the resulting salt is disposed of.
The generally accepted scheme at refineries covers three stages of purification:
1) mechanical cleaning of liquid and solid impurities;
2) physical and chemical treatment of colloidal particles, neutralization of sulfur-alkaline waters and sewage from electric desalination plants (ELOU);
3) biological treatment of dissolved wastes. In addition, additional treatment of biologically treated wastewater is carried out.
Sand traps are primarily used among mechanical treatment plants. They contain 0.15-0.2 mm of mineral impurities and emit about 25% of the oil products in the wastewater. Swinging pipes have been installed in sand traps to collect oil.
After the sandblasters, the wastewater is sent to the oil tankers, where particles with hydraulic dimensions of 0.8 mm / s are removed and the cleaning lasts about 2 hours, after which the water contains 50-200 mg / l of oil products. Additional sludge ponds or radial settling tanks equipped with devices for collecting oil products are used for post-treatment of wastewater from oil traps.
It is recommended to use thin-layer oil traps. Slabs are made of steel or plastic, separate blocks are assembled and installed at an angle of 45o, at a distance of 100 mm. Tiles can be straight or corrugated. The use of such oil traps allows to reduce the amount of oil products in wastewater to 1525 mg / l [3].
It is planned to increase the amount of oil products in wastewater to 20-30 mg / l in sand filters. The height of the loading layer is 1-1.2 m, filtration is carried out from the bottom to the top at a speed of 5-15 m / h. However, the restoration of such filters is complicated and inefficient, and they are often abandoned. Recently, fibrous or floating (polyethylene foam) loads are increasingly used for the extraction of petroleum products. The use of hydrocyclones for mechanical cleaning is promising.
However, the purification and recycling of petroleum products from wastewater is possible with the help of physicochemical and biological methods. One of them is coagulation. Aluminum and iron salts are mainly used as coagulants; Lime milk is used to keep a certain pH value constant.
The oil industry is a potentially dangerous production for the environment. Practically at all stages of development of oil fields there is an impact on the subsoil, soil and vegetation cover, atmospheric air, surface and ground waters. In many cases, especially during the development of large deposits, landscapes and ecosystems change, there is a negative impact on the animal world and, finally, on the health of both workers in oil producing enterprises and the population of nearby settlements.
In the processes of field collection and preparation of oil, gas and water, reservoir waters are polluted with various chemicals, mixed with various effluents (bottom water, runoff from the territory, etc.), forming SSW, which are highly mineralized effluents, containing suspended particles of various composition and origin, emulsified and dissolved oil, hydrogen sulfide, various chemicals, primarily surfactants, are characterized by high corrosiveness.
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The most rational way to solve the problem of NSW disposal is to use them in the system of reservoir pressure maintenance of oil fields, which makes it possible to drastically reduce the volumes of fresh water used for the purposes of reservoir pressure maintenance and at the same time prevent pollution of water bodies by sewage.
When disposing of NSV into the system of reservoir pressure maintenance of oil fields, it is necessary to solve two main problems:
1) develop science-based technological requirements for the quality of wastewater injected into productive strata;
2) to develop equipment and technology for the treatment and preparation of wastewater to bring their quality to the technological requirements for water quality.
Water injected into productive formations should:
- have high filtration and oil-displacing properties;
- contain suspended impurities within the limits that do not affect the injectivity of injection wells during long-term operation;
- be compatible with formation water and formation rock;
- not lead to violation of the conditions of ecological balance in the oil reservoir.
Long-term laboratory and field studies carried out at the institutes of the industry make it
possible to compare the filtration and oil-displacing properties of various types of water.
Science-based requirements for the quality of injected water include criteria for stability and compatibility with formation water and formation rock, maximum allowable concentrations of impurities; special attention is paid to the regulation of the content of solid suspended particles and oil.
The most promising options for reusing drilling waste can be considered to be the production of clay powders in the production of various building materials, when cementing the annulus. In some regions, under appropriate conditions, it is possible to inject drilling waste into absorbing wells.
A comparative analysis of the methods of disposal and disposal of the non-utilizable part of drilling waste showed that the most rational is their disposal on site immediately after the completion of well construction. Of all the methods of disposal and disposal, in the opinion of the authors, the most expedient is the use of the method of curing waste in barns using binders and the biological decomposition of toxic compounds contained in drill cuttings [5].
Accounting for all possible types and sources of impact of the oil industry on the natural environment, the extent of changes in the state of the environment should be identified when performing the impact assessment procedure (EIA Figure 1). EIA is carried out in order to prevent degradation of the environment, restore natural systems disturbed as a result of previous economic activity, ensure the ecological and economic balance of future economic development, create favorable living conditions for people, develop measures that reduce the level of environmental hazard of the planned activity, and should precede the adoption of decisions on the implementation of a project.
Figure 1. Schematic representation of the coalescing filter-settler EIA 1 - container, 2 - grids, 3 - loading zone, 4 - pre-settlement zone, 5 - supply pipe, 6 -overflow wall, 7 - oil layer, 8, 9 - inclined shelves , 10 - perforated partition.
The settling filter is made in the form of a horizontal tank I with a volume of 100 m , divided by transverse partitions 2 into compartments, each of which has built-in mesh filters that form between themselves pre-settlement chambers /199, 200/. The filters are filled with coalescing media 3 made of granular hydrophobic polymer material (polyethylene, polystyrene, etc.). Overflow baffles 6 are installed near the filters. Shelves are installed in the settling zone 7 to improve the coalescence process in the oil layer.
The sump filter works as follows. Waste water is fed through a perforated pipe 5 into the preliminary settling chamber 4, from where it enters the coalescing filters 3, where the oil globules are enlarged on the surface and in the pore space of the granular hydrophobic load.
Enlarged oil globules are carried out by the flow of purified water from the filter and through the overflow partition 6 enter the oil layer of the settling zone 7, where the final purification of wastewater from emulsified oil takes place. Coarse suspended solids are separated in the preliminary settling chamber 4. After that, wastewater with solid particles smaller than 100 microns enters the coalescing filter, where they stick to oil globules. From the filter, solid suspended particles with oil globules are carried out into the oil layer in the settling zone 7. The sediments accumulated in the bottom part of the coalescing filter-settler are periodically removed. Solid suspended particles that have passed into the oil layer gradually accumulate at the oil-water interface, so it is necessary to renew the oil layer in the settling zone [4].
At the enterprises of the oil industry, oil sludge is formed during the extraction, field preparation and transportation of oil in the fields and pumping stations. Oil sludge is accumulated in open storage pits, which were previously included in the oil treatment process flowsheet, where oil-containing products trapped in the water treatment circuit, intermediate emulsions from separating apparatuses and process tanks, substandard oil, etc. are also discharged. The accumulation and storage of oil sludge in barns has been going on for decades. At present, their number in Russia is more than 1 million tons, and taking into account trap emulsions, it is several times higher [8].
Oil sludge is an abnormally stable emulsion, constantly changing under the influence of the atmosphere and various processes occurring in them . Over time, natural "aging" of emulsions occurs due to compaction and hardening of the armor shells on water drops, evaporation of light fractions, oxidation and gumming of oil, transition of asphaltenes and resins to another quality, formation of colloid-micellar conglomerates, penetration of additional mechanical impurities of inorganic origin. The resistance to destruction of such complex multicomponent disperse systems increases many times, and their processing and utilization is one of the most difficult tasks.
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