CC BY
15
Hudayberdiev Absalom Abdurasulovich, Candidate of Technical Sciences, Senior Researcher of the Laboratory "Processes and Apparatus of Chemical Technology" Institute of General and Inorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan
Tashkent, Uzbekistan E-mail: [email protected].
TECHNOLOGY OF INTENSIVE HEATING OF OIL RAW MATERIAL BY DEGREARED FACTORES
Abstract. a critical analysis of the technology of distillation of oil with superheated water vapor; proposed a new technology for the use of dehydrated vapors of distillate fractions during atmospheric distillation of oil and in the process of its heating; The technological efficiency of the use of this technology and the degree of intensification of the process in the heat exchangers of the oil refinery are shown.
Keywords: oil, distillation, steam, heat of condensation, heating, heat exchanger; intensification, effectiveness.
According to the existing technology of motor fuel production, the distillation of hydrocarbon raw materials (oil, gas condensate and their mixtures) and the distillate distillation of fuel fractions is carried out using superheated water vapor (1 MPa, 450 °C) [1-3]. Introduced in the bottom part of a complex distillation column and its stripping sections, the acute superheated water vapor increases the degree of evaporation of the raw material components by reducing the partial pressure of hydrocarbon vapors, which allows the process to be distilled at lower temperatures [1; 2; 4].
The consumption of water vapor in the process of atmospheric distillation of crude oil is 2.0 ^ 6.5% [2; 5], depending on the consumption of raw materials, its composition and process parameters.
Analysis of the existing technology for the distillation of oil with water vapor showed [2; 5; 6] that:
- in the process of distillation, water vapor, being in close contact with raw materials and petroleum products, is saturated with hydrocarbon vapors and forms a heterogeneous steam mixture;
- water vapor, which is in the composition of vapor fractions, from a technological point of view is a foreign agent; it occupies a certain part of the technological volume of the apparatus, which leads to an increase in their overall dimensions and mass in the design stage;
- the steam mixture formed during the distillation is characterized with different values of the latent heat of condensation of the constituent components, which complicates the conditions of the process of condensation of the steam mixture, prevents intensive flow of the conducted heat and mass transfer processes during steam condensation and reduces the technological efficiency of the apparatus;
- the formed condensate of water vapor (acidic water) enhances the corrosion of the working surfaces of the apparatus and the pipelines to them;
- in subsequent stages, when the process condensate is separated from water, there is a probability of watering of motor fuel and the need for its subsequent drying.
In addition, "polluted" as with oil fractions, and sulfur, nitrogen and other impurities, waste water must also be cleaned, which will require additional costs.
For these reasons, from the technological point of view, it is advisable to drastically reduce the consumption of water vapor for the distillation of hydrocarbons or to conduct this process without its participation.
According to the results of research carried out by us under the leadership of academician ofthe Academy of Sciences of the Republic of Uzbekistan Z. Salimov, the technology of "dry" distillation of oil and gas condensate feedstock using alternative (instead of water vapor) coolant - fuel fractions leaving the atmospheric distillation column at high temperatures [6; 7].
According to the technology proposed by us, a pair of dehydrated distillates of fractions formed during the distillation will be used as a heating agent. In this case, due to the lack of water in the composition of the heating steam, part of the volume of the annular space of the heat exchangers of the refinery, previously occupied by water vapor, is released. At the same time, the released technological volume of the apparatuses is as much as the water vapor previously occu pied (2.0 * 6.5%).
Such an additional increase in the technological volume of the apparatus leads to the intensification of heat and mass transfer processes during the condensation of homogeneous hydrocarbon vapors and increases the technological efficiency of heat exchangers, which is confirmed by the results of our own experiments [8].
The lack of water eliminates the accumulation in the casing of the apparatus of air and non-condensable gases emitted from the composition of water vapor during its condensation. This helps to improve the condition of condensation of homogeneous composition of hydrocarbon vapors and leads to an increase in the coefficient of heat transfer from steam to the tubular heating surface of the apparatus.
The generalized positive impact of the above factors is the basis for the intensification of the pro-
cesses of thermal preparation (heating) of crude oil during vapor condensation and cooling of distillates of fuel fractions in tubular heat exchangers.
As is known, one of the most important advantages of hydrocarbon vapors is the low heat of their condensation rd compared to the heat of condensation of water vapor [9; 10].
A comparison of the heat of condensation of hydrocarbon vapors and water at P = 250 kPa showed that hydrocarbon vapors have a measured condensation temperature t = 145 °C and a calculated rd = 255.88 kJ/kg [9]. According to [11], at 250 kPa, the tabular values of the corresponding indicators of water vapor are temperature.
Therefore, in this case, the ratio
r /r, = 2174.7255.9 = 8.5, (1)
wv el / \ /
indicates, as far as possible, to intensify the process of heat exchange in the apparatus at no additional cost, reduce the required heat transfer surface at a given heat exchanger capacity, or increase its thermal capacity.
The share of the released technological (annular) space of heat exchangers KV (%) used to intensify the processes of heat and mass transfer can be defined as the ratio of the costs of water G and hydrocarbon
wv '
vapor Gel:
Kr = (G /G,) • 100% = (G /VpKK) • 100%,(2)
V v wv eV v wv n n 3 ' \ /
where G and G are determined from the material
wv el
balance of the distillation process, kg/h; VH - atmospheric distillation column capacity for raw materials, m3/h; pH - density of raw materials, kg/m3; KS - coefficient of loading of raw materials in an oil refinery; K - the rate of release of target fractions,% of the mass.
The value of KV can also be determined by the costs of leaving the oil fractions Gfr.
KV=(Gwv/Gfr)100% = (Gwv/(Gga+Gker+G J10^ (3)
where G , G, and G, are the amount of the main
ga ker diz
product produced in the installation (gasoline, kerosene and diesel fuel), kg/h.
The value of KV shows how much it is possible to increase the volume of the produced products us-
ing carbon vapors instead of water vapor, without overloading the composite apparatus of the refinery.
The increase in thermal efficiency K^ of the heat exchanger, achieved due to the intensification of heat transfer in it, can be defined as:
\ = (rm/rj • Kv (4)
For example, for an oil refinery heat exchanger in which oil is heated during condensation of fraction vapors, the increase in its thermal efficiency in (4) is: = (rwv/rel) • Kv = (2019.9/245.3) • 2.47 = 20.34%, where rwv = 2019.9 kJ/kg is the heat of condensation of superheated steam at 180 °C and pressure of 1.0 MPa [11]; rd = 245.3 kJ/kg - heat of condensation of vapors of distillate fractions at 180 °C.
The efficiency of using hydrocarbon vapors during the primary distillation ofoil in the ELOU-AVT-3 unit of the refinery can be shown by calculation using
the following integrated technological parameters of this unit: unit capacity for oil is 240 m3/h, unit loading rate is Vn = 180 m3/h; the number of factory days per year - T = 365 days; oil density - pn = 844 kg/m3; the coefficient of irregularity of the installation is assumed to be K = 0.9.
ir
At the same time, the minimum share of the released technological space Kv of the main apparatuses of the oil refining plant according to (4.2) is: KV=GJ(24 • Vnpn)100% = 90/(24 • 180 • 0.844)100%= = 2.47%.
The value of Kv = 2.47% indicates the possibility of producing heat treatment of raw materials by 2.47% more or reducing the technological load on heat exchangers (condensers, heat exchangers, air and water coolers) by 2.47% at a given installation capacity (see Table 1).
Table 1.- Technological indicators of the effectiveness of the use of hydrocarbon coolant in the installation ELOU-AVT-3
№ Indicators Units Values of indicators
1 The load rate of the installation ELOU-AVT-3 m3/hour 180
2 The number of products obtained (according to the regulations):
- gasoline t/day 540
- kerosene TS-1 t/day 465
- diesel fuel t/day 917
3 Consumption of water vapor for the distillation of oil t/day 90-120
4 (according to the regulations) t/day
Daily amount of additionally produced products at K = 2.47%: t/day 13.338
- gasoline t/day 11.416
- kerosene TS-1 t/day 22.65
5 - diesel fuel
Annual volume of additional output at Vr = 0.9: t/year 4381.5
- gasoline t/year 3750.2
- kerosene TS-1 t/year 7440.5
Judging by the data in the table and taking into account the large volume of oil refined by the plant (2 - 10 million tons per year), the indicators of introducing its technology of thermal preparation for
primary distillation using alternative heat carrier (instead of water vapor) will be significant.
Thus, the intensification of the process of heating the crude oil in tubular heat exchangers using
dehydrated vapors of distillate fractions contributes to development of scientific and practical fundamentals
an increase in the thermal efficiency of the apparatus, of an intensive technology of thermal preparation of
the design ofhigh-intensity compact apparatus and the the crude oil to atmospheric distillation.
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