1. Scope of fuel oil
Fuel oil (possibly from the Arabic mazkhulat - garbage), liquid product dark brown, the residue after separation from oil or products of its secondary processing of gasoline, kerosene and gas oil fractions, boiling up to 350-360°C. Fuel oil is a mixture of hydrocarbons (with a molecular weight of 400 to 1000 g/mol), petroleum hydrocarbons (with a molecular weight of 500-3000 g/mol or more), asphaltenes, carbenes, carboids and organic compounds containing metals (V, Ni, Fe, Mg, Na, Ca).
Fuel oils are used as fuel for steam boilers, boiler plants and industrial furnaces. The output of fuel oil is about 50% by weight based on the original oil. Due to the need to deepen its further processing, fuel oil is subjected to further processing on an increasing scale, distilling distillates under vacuum, boiling in the range of 350-420, 350-460, 350-500 and 420-500 ° C. Vacuum distillates are used as raw materials for the production of motor fuels and distillate lubricating oils. The residue of vacuum distillation of fuel oil is used for processing at thermal cracking and coking units, in the production of residual lubricating oils and tar, which is then processed into bitumen.
The main consumers of fuel oil are industry and housing and communal services. In 2005, Russia exported 45.8 million tons of fuel oil worth $10.2 billion. Fuel oil ranks fourth after oil, gas and diesel fuel in Russia's export structure (in monetary terms).
Lubricating oils are obtained from fuel oil by additional distillation for lubricating various mechanisms. The distillation is carried out under reduced pressure in order to lower the boiling point of hydrocarbons and avoid their decomposition when heated. After the distillation of fuel oil, a non-volatile dark mass remains - tar, which is used for asphalting streets.
Fuel oil superlight is used as process fuel on industrial enterprises, at heat supply enterprises, as well as on ships of the sea and river fleet.
2. Physical and chemical properties of fuel oil
Fuel oil superlight contains 25-50% stabilized gas condensate with the content of fraction C1-C4 in it in the amount of not more than 0.3-1.0% and the rest fuel oil grade M100 and/or M40.
The physicochemical properties of fuel oil depend on the chemical composition of the original oil and the degree of distillation of distillate fractions and are characterized by the following data: viscosity 8-80 mm 2 / s (at 100 ° C), density 0.89-1 g / cm 3 (at 20 ° C), pour point 10-40°C, sulfur content 0.5-3.5%, ash up to 0.3%, net calorific value 39.4-40.7 MJ/mol. A typical distribution of tar-asphaltene substances in fuel oil is presented in Table. 2.
Table 2.
The main characteristics of fuel oil are: density, viscosity, and pour point, which are described in more detail in Table. 3.
Table 3
| Index | Norm by brand |
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| Naval | Furnace |
|||
| Viscosity: at 50 0 C, not more than conditional, 0 VU kinematic, cSt at 80 0 C, no more than conditional, 0 VU kinematic, cSt | ||||
| Temperature, 0 С: solidification, not higher | -7/-5 | -8 | 10 | 25 |
| Density at 20 0 С, kg/m3, not less than | 910/955 | 930/960 | 965/1015 | 1015 |
Experimental batches of fuel have been successfully completed and have given positive results. 2. Economic analysis and evaluation competitive environment JSC "TAIF-NK" 2.1 Technical and economic characteristics of the enterprise The historical necessity of creating an oil refining industry in Tatarstan was dictated by economic expediency. The republic, which has large reserves of hydrocarbon raw materials and ...
With or without stripping columns. When stripping columns are used, several circulation refluxes are arranged along the height of the main vacuum column. The schematic diagram of the block of vacuum distillation of fuel oil of the ELOU-AVT-6 unit is shown in Figure 2. The fuel oil taken from the bottom of the atmospheric column of the AT block (see Fig. 1) is pumped in parallel flows through the furnace 2 into the vacuum column 1. The mixture...
ISSUES OF REFORMING AND RESTRUCTURING OF ENTERPRISES. A few years ago, as one of the measures to solve the problem of a decline in production, a variant of reforming and restructuring enterprises with the involvement of consultants arose. Individual examples of a significant improvement in the financial and economic condition of an enterprise due to the activation and use of its internal capabilities have also appeared. TO...
Production and sale of products, however, it is necessary to maintain the achieved level of production costs. 3. The main directions of cost reduction at the enterprise on the example of TAIF-NK Oil Refinery OJSC 3.1 Ways to reduce fixed costs at the enterprise The activity of any firm involves the implementation of costs. To get the maximum possible profit, it is necessary to reduce the cost of...
Magazine "Heat Supply News", No. 6 (10) June 2001, pp. 15 – 18, www.ntsn.ru
Ya.M. Shchelokov
Fuel oil has a number of undoubted qualities as a fuel:
1. High calorific value -9500 kcal/kg.
3. The possibility of obtaining a luminous flame that provides high radiation heat transfer in the furnace space.
4. Possibility of organizing certain conditions, its combustion in small furnaces.
But fuel oil, as a fuel, has a number of serious disadvantages:
1. Unstable composition of each batch of fuel oil - from close to oil to mainly in the form of high-viscosity cracked residues. In the latter case, the nozzles quickly coke, and the combustion process is delayed.
2. Increased safety requirements. For example, the flash point is not higher than 100-120°C.
3.High sulfur content, about 3.5%>
4. Heat hardening + (25-30 ° C).
5. High price, especially lately.
But, in our opinion, the most significant disadvantages of fuel oil are as follows: inconvenience in operation caused by the multi-stage preparation of fuel oil for use: heating, draining, organizing storage without separation into fuel oil and water, heating and mixing in tanks, transportation through pipelines, additional heating before nozzles, spraying, combustion, prevention of corrosion processes in boilers and environmental consequences in terms of the composition of emissions into the atmosphere and the discharge of oily water, ensuring safety requirements. And for each stage of preparation and use should be provided high quality execution. This requirement is not subject to exceptions.
High-cost mechanism for the use of fuel oil:
Only the standard for heat losses for own needs is more than 10% (for natural gas - 3%);
Electricity costs for pumping;
Additional personnel for the discharge of fuel oil, the organization of its storage, etc.;
Elevated temperatures for flue gases behind the boiler, to reduce their corrosiveness, etc.
That is, fuel oil requires a responsible, qualified and sober attitude at all stages of its use.
Preparation of fuel oil for combustion
The preparation of fuel oil for use begins with one of the most important operations - heating it up in tanks and draining it for storage. Heating in this case is carried out by supplying fresh steam to the fuel oil layer using rods or flexible metal hoses. In this case, large steam leaks and watering of the fuel oil occur. Moreover, the main part of the moisture gets into the fuel oil during the cleaning of tanks. During this time, fuel oil is watered by 2-4.5%. The main performance indicators of the devices when heating fuel oil grade M-100 with fresh steam with parameters of 12 atm and 280 ° C (tank volume 50 m 3, air temperature -10 ° C):
Ensuring the optimal temperature for draining is not lower than 60 °C with a total steam consumption per tank of about 2.7 tons with a draining time of 5.5 hours.
In the case of using steam with lower parameters, its consumption increases by 15-20%.
In this case, it is recommended to drain most of the fuel into the main fuel oil tanks before the start of cleaning the tank. And when cleaning the tank, watered fuel oil should be poured into a special intermediate tank. In this case, the amount of condensate supplied with fuel to the main fuel oil tanks can be reduced by 2-5 times, i.e. reduce water cut to 0.5-1.0%. Such a division of fuel by moisture will allow differentiation to approach the issue of organizing its combustion. Water in fuel oil affects the efficiency of its use. If poorly mixed watered fuel oil is supplied to the nozzles, combustion pulsations are observed, which also lead to flame failure. There is also an excessive consumption of fuel due to underburning.
At the same time, when fuel oil is burned with water well dispersed in it, with its content of 5-10% or even more, the atomization efficiency increases, combustion stability increases, and the content of harmful emissions (nitrogen oxides, carbon oxides, etc.) decreases. Therefore, when preparing fuel oil for combustion, it is necessary to ensure:
Low (up to 3%) water content in fuel oil;
Deep mixing of water with fuel oil;
Required fuel oil heating temperatures.
The decrease in water content was mentioned above. With a low degree of watering, the necessary mixing of fuel oil can be provided by implementing its circulating heating. In this case, the fuel from the tank is pumped to a special external heater and then heated back to the tank. In the presence of heaters inside the tank, as a rule, it is sufficient to organize the recirculation of fuel oil in the tank before supplying it to the nozzles.
Additional heating of fuel oil in front of the nozzles is desirable, especially for mechanical atomization. But at the same time, it should be ensured that the heat exchanger tubes provide the necessary vapor density in order to avoid additional watering of the fuel oil.
Options temperature regime when heating fuel oil are given in table.1.
At all stages of fuel oil preparation, it should be possible to measure and control its temperature.
Oil pipelines
To prevent clogging of oil pipelines and especially nozzles, it is necessary to provide for the installation of coarse and fine filters. A 100% margin for their throughput must be provided.
The dimensions of the fuel oil supply lines depend on the fuel consumption (see Table 2).
When calculating the supply steam and air ducts, it is recommended to take the following medium movement speeds (m / s): for saturated steam 20-30, superheated steam 30-60, fan and compressor air - 10-15 and 15-20, respectively.
Fuel oil pipelines are laid with satellites-steam pipelines in the same insulation. It is obligatory to provide for the possibility of purging fuel oil pipelines with steam.
Fuel oil combustion
The temperature parameters of fuel oil before its combustion are shown in Table 1. Steam (steam-mechanical) or mechanical nozzles are used in boilers for spraying fuel oil. What are the requirements for their selection?
Currently, boilers most often provide for the installation of mechanical nozzles. The minimum allowable fuel oil pressure in front of them is 18 atm. Table 3 shows the required dimensions of the injector nozzle depending on the fuel oil consumption (fuel oil pressure 18 atm).
The diameter of the outlet section of the fuel oil nozzle should be taken to avoid clogging and coking at least 3 mm, even if a smaller value is obtained by calculation. That is, all nozzles with a flow rate of less than 500-550 kg / h must have a nozzle of at least 3 mm in diameter, and therefore must be steam mechanical or steam in their design with a steam flow rate of up to 10% of the fuel oil consumption. The speed of fuel oil from the nozzle should be about 60-80 m/s. In the case of using steam-mechanical nozzles on hot water boilers, the steam flow should be limited as much as possible to avoid sulfur corrosion of screen pipes.
From Table. 3 also shows that when the nozzle diameter is changed by 0.5 mm, the fuel oil consumption increases from 500 to 680 kg/h, that is, by almost 40%. Therefore, it is necessary to calibrate the nozzles on the stand when water is supplied, which allows:
Select nozzles with the same flow rate;
Ensure the visual quality of spraying;
Determine the opening angle of the torch;
Ensure that the fuel flow through the nozzle corresponds to the required burner (boiler) parameters.
The air speed in the burner should be about 40 m/s. In this case, it is possible to avoid chemical underburning. It is advisable to provide a high degree of turbulence air flow from the burner (use of blades). In this case, the absence of mechanical underburning is ensured. It is also advisable to heat the air to a temperature of 15b-200°C.
For burners with fuel oil consumption of 450 - 550 kg/h, the flame length in the furnace should not exceed 2.5 m. It is allowed to increase the visual length of the torch by approximately 1 m for every 200 kg/h increase in fuel consumption through the burner. The fuel oil torch should not hit the lining, and even more so in the heating surface. It is unacceptable.
On oil-fired boilers, it is imperative to ensure a scale-free operation of the boilers by softening the water or treating it with antiscale SK-110. This alone can reduce fuel consumption by 20-25% and reduce the amount of repair work.
If the oil-fired boiler has convective heating surfaces, an air heater, then the flue gas temperature should not be lower than 155-160 °C in order to avoid sulfuric acid corrosion. Local "overcooling" of pipes, metal lining, etc. is unacceptable. due to the supply of cold air to the gas duct, etc. Corrosion damage is inevitable in these places.
Conclusion
AT Soviet time fuel oil was normatively (in SNiP, OST, GOST) registered as the main, reserve, emergency, process fuel. As a result, a large number of facilities appeared where fuel oil was the only and indispensable fuel. Which is what many are trying to keep until now. But the situation has changed radically:
The price of fuel oil is 3-5 times higher than the average for fuels;
Fuel oil is not distributed, but purchased at the so-called. market;
Its use becomes costly (large own needs, high sulfur content, etc.).
Therefore, fuel oil practically in all its parameters does not meet the requirements that the main and reserve fuel should provide simultaneously. This implies:
Operation of heat sources on which fuel oil and the main and reserve fuel cannot be reliable in terms of avoiding emergency situations;
Fuel oil now itself requires a reserve fuel, and in some cases, its complete replacement with local fuels.
In table. For comparison, Figure 4 shows approximate indicators of the operation of a hot water boiler house with boilers with a rated power of 6.5-10 Gcal / h, depending on the type of fuel combustion. The economic performance of local fuels is higher than coal fuel, and fuel oil, but economic indicators for local fuels, the potential harmfulness (hazard) of combustion products is practically at the level of the hazard of natural gas combustion products.
In the production of many products such as engine oils, coke, bitumen, lubricating oils, etc., fuel oil is used. In addition, fuel oil is also used as a boiler fuel.
Fuel oil is a petroleum product, but it can also be produced from hard coal, as well as oil shale, however, these variants of fuel oil are intended for consumption at the place of production, and therefore are not produced in large quantities.
Fuel oil is a mixture of a large number of different components, among which there are some organic compounds, petroleum resins, carbenes, hydrocarbons with a molecular weight of 400-1000 g/mol. The consistency of fuel oil is liquid, and the color is dark brown.
Currently known the following types fuel oil: furnace, straight-run, cracked fuel oil, naval, furnace household fuel.
Fuel oil is a residue of the primary distillation of oil and can be used as a boiler fuel - lightweight fuel oil (above 330? C), as well as as a raw material, subsequently processed into oil fractions to tar, which is used in the production of oils - heavy fuel oil (above 360 ?FROM).
In addition, if earlier fuel oil was used as a feedstock for thermal cracking units, today it is also used as a feedstock for hydrocracking and catalytic cracking units.
Using different compositions and physical and chemical properties of the starting material, it is possible to obtain fuel oil with different properties. Depending on the density, viscosity and sulfur content of fuel oil, its quality is assessed. The density of fuel oil is determined at a temperature of 20? C, and it should be 0.89 - 1 gram per cubic centimeter.
Not less than important parameter quality assessment is the pour point, which varies from 10 to 50?C, but the exception is marine fuel oil, for which this temperature ranges from minus 5 to minus 10?C. The viscosity of fuel oil should be in the range of 8-80 mm2/s and is measured at a temperature of 100°C.
Today, a large amount of fuel oil is processed, and as a result of processing, distillate lubricants and motor fuels are obtained. Despite the fact that fuel oil is used in many industries, its main consumers are industrial enterprises, as well as housing and communal services.
Fuel oil is used in the engines of marine vessels and diesel locomotives, but is most widely used as a fuel for steam boilers, industrial furnaces and boiler plants.
The peak of fuel oil consumption falls in the winter season, however, this does not mean that there is no demand for it in the rest of the year.
In modern times, the most popular fuel oil is M-100.
fuel oil It is widely used as a boiler fuel and is a valuable raw material for the chemical industry. As a high molecular weight fraction of oil, fuel oil is a dark and thick liquid.
The main indicator of the quality of fuel oil during its labeling is viscosity, determining the conditions for filling and draining tanks, tanks, tankers and other containers, transporting fuel oil through pipelines, supplying it to the furnace space of furnaces, etc. The viscosity of fuel oil is estimated in units of conventional viscosity (°VU) and is determined by the ratio of the continuous outflow time of 200 ml of fuel oil at a given temperature to the outflow time of the same volume of distilled water at a temperature of 20 °C. The viscosity of the oil depends on temperature, density and resinous. At low temperatures, the viscosity of fuel oil increases significantly, so it can be drained from tanks and pumped through pipelines only after fuel has been preheated.
Pour point of fuel oil depends on the chemical composition of the raw material and the methods of obtaining the oil product. Straight-run fuel oils from paraffin oil have a pour point of more than 25 ° C, and cracked fuel oils - from 25 to 34 ° C.
When calculating the volumes of tanks for storing and transporting fuel, determining the conditions for settling water and settling mechanical impurities from fuel oil, the indicator is used fuel oil density . The lower the density of fuel oil, the easier and faster water and mechanical impurities are separated from it. The density of fuel oil ranges from 0.94-1.02 g/cm 3 and increases with increasing viscosity.
Flash point characterizes the fire safety of fuel and the conditions of handling it during transportation, storage and use. The maximum heating temperature of the fuel must be at least 10°C below the flash point. The flash point of commercial fuel oil, determined by known methods in closed and open crucibles at 80-90°C.
Ash content of fuel oil depends on the quality of preparation and processing of raw materials and is determined by the content of salts, inorganic impurities, additives used, as well as corrosion products of oil equipment.
At present, as a result of improving the processes of preparation and processing of oil in the industry, the ash content in commercial fuel oils has significantly decreased.
Sulfur content in boiler fuel depends on the chemical composition of the original oil and is: for high-sulphur fuel oils - up to 3.5%, for sulfur - up to 2.0% and for low-sulphur - up to 0.6%. The combustion of sour oil leads to the formation of acid oxides, which cause increased corrosion of parts of boilers and apparatus, and pollute the environment. Hydrogen sulfide and elemental sulfur are particularly corrosive. Therefore, low-sulphur fuel oils are primarily used in technological heating installations: open-hearth furnaces, heaters foundry, rolling and other enterprises of the metallurgical industry.
Water and mechanical impurities get into fuel oil from oil during production and transportation operations and are ballast during transportation. When burning flooded fuel oils, the efficiency of boilers decreases and conditions for equipment corrosion are created, and the inorganic part of mechanical impurities does not burn out during the combustion process and increases the ash content of fuel oil. The content of water and mechanical impurities in fuel oil should be minimal. To reduce the effect of harmful impurities and improve the non-stick and anti-corrosion properties, additives are added to fuel oils.
The oil refining industry produces several brands of fuel oil used as fuel: naval F-5 and F-12, furnace 40 and 100 . The numbers included in the grades (5, 12, 40 and 100) indicate the maximum viscosity at a temperature of 50 ° C in units of conventional viscosity. Fuel oils F-5 and F-12 (light fuel) are used in ship boiler installations, and grades 40 (medium fuel) and 100 (heavy fuel) are used as bulk fuel in all general-purpose boilers and heating installations. Oil grades 40 and 100 are subdivided according to the sulfur content into: low-sulfur, sulphurous and high-sulphurous.
Fuel for open-hearth furnaces is supplied grades: MP - low-sulfur and MPS - sulphurous. Gas turbine fuel is produced in two grades: TG - conventional and TGVK - the highest quality category, and household furnace fuel is produced under the TPB grade.
From 400 to 1000), petroleum resins (with a molecular weight of 500-3000 or more), asphaltenes, carbenes, carboids and organic compounds containing metals (, , , , , ). The physico-chemical properties of fuel oil depend on the chemical composition of the original oil and the degree of distillation of distillate fractions and are characterized by the following data: viscosity 8-80 mm²/s (at 100 °C), density 0.89-1 g/cm³ (at 20 °C) , pour point 10-40°C, sulfur content 0.5-3.5%, ash up to 0.3%, net calorific value 39.4-40.7 MJ/mol. A typical distribution of tar-asphaltene substances in fuel oil is presented in table 1.
Application
Fuel oils are used as fuel for steam boilers, boiler plants and industrial furnaces (see Boiler fuels), for the production of marine fuel oil, heavy motor fuel for crosshead diesels and bunker fuel. The output of fuel oil is about 50% by weight based on the original oil. In connection with the need to deepen its further processing, fuel oil is subjected to further processing on an ever larger scale, distilling distillates under vacuum, boiling in the range of 350-420, 350-460, 350-500 and 420-500 ° C. Vacuum distillates are used as raw materials for the production of motor fuels, in the processes of catalytic cracking, hydrocracking and distillate lubricating oils. The residue of vacuum distillation of fuel oil is used for processing at thermal cracking and coking units, in the production of residual lubricating oils and tar, which is then processed into bitumen.
Approximate composition of commercial fuel oil may include:
1. Fuel oil atmospheric distillation of oil
2. Tar
3. Vacuum gas oils
4. Extracts of oil production
5. Kerosene-gas oil fractions (primary and secondary)
6. Heavy catalytic cracking and coking gas oils
7. Bitumens
8. Remains of visbreaking
9. Heavy resin pyrolysis
The main consumers of fuel oil are industry, fleet and housing and communal services.
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