RU2537176C1 - Hydrocarbon fractions stabilisation method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes delivery of heated non-stable hydrocarbon fraction into the middle part of the stabiliser, which top is cooled and the bottom is heated, output of vapours from the top and output of the stable hydrocarbon fraction from the stabiliser bottom. A fractionating unit with falling film that includes the upper and lower sections of heat-mass-exchange elements and the feed zone placed between them is used as the stabiliser. The heat-mass-exchange elements comprise shaped vertical surfaces, which form inner space for passage of heat carrier or cooling agent and outer space for counterflow of liquid and vapour. The lower unit is heated by feeding of the heated non-stable hydrocarbon fraction as heat carrier to the bottom part of the heat-mass-exchange elements in the lower section; the fraction is outputted up to the unit top, constricted up to stabilisation pressure and feed to the feed zone. The upper part of the unit is cooled by feeding of the coolant to the top part in the inner space of the heat-mass-exchange elements in the upper section; the coolant is outputted from its bottom part. The stabilising gas is outputted from the top of the fractionating unit as stabilisation vapours.

EFFECT: reducing steel intensity, excluding costs of electric energy, decreasing energy costs.

1 dwg, 1 ex

Description

The invention relates to methods for stabilizing hydrocarbon fractions and may find application in the oil refining industry for the production of kerosene, diesel fuel, mineral oil with a standard value for flash point or gasoline with a standard value for saturated vapor pressure.

A known method of stabilizing the hydrogenate on the stabilization site of the installation of hydrotreatment of diesel fuel [Album technological schemes of oil and gas processing, edited by B.I. Bondarenko, M .: Publishing House of the Russian State University, 2003, p.72], which includes the separation of the reaction mass of the hydrotreatment process into a circulating hydrogen-containing gas and unstable hydrogenate, which is stabilized by blowing off with hot steam in a stripping column to produce hydrocarbon gas, gasoline, refined (stable) diesel fraction and oil-contaminated condensate of water vapor, as well as heat recovery of a stable diesel fraction.

The disadvantages of this method are: the use of water vapor, the formation of oil-contaminated water effluents, the need to use a large number of equipment with high metal consumption.

Closest to the claimed method according to the technical nature and adopted as a prototype installation of stabilization of hydrocarbon mixtures [Patent RU 2194739, IPC C10G 7/02, C10G 49/00, publ. December 20, 2001]. The patent describes a method for stabilizing an unstable hydrogenate of diesel fuel by splitting into two streams of an unstable feedstock (unstable hydrocarbon fraction) obtained by separation of the hydrogenate, a larger stream is heated in a recuperative heat exchanger with a bottom product (stable hydrocarbon fraction) and fed to the middle part of the stabilization column, the rest of the stream mixed with the gas mixture leaving the stabilization top (stabilization pairs), cooled in air and water coolers, and a separator They are injected in a reflux tank to produce reflux, which is fed to the top of the stabilization column, stabilization gas and acidic water with a reflux pump, which are sent for disposal. Heat is supplied to the bottom of the stabilization column due to a “hot stream” obtained by circulating the bottom product through a fire-heating furnace using a circulation pump. A stable bottoms product is removed from the bottom of the stabilization column, which is successively cooled in a recuperative heat exchanger, air and water coolers, and removed from the unit.

The disadvantages of this method are: the use of a "hot stream" for heating the bottom of the stabilization column, which reduces the efficiency of fractionation, and the ingress of heavy hydrocarbons into the strengthening part of the stabilization column, which also reduces the efficiency of fractionation and leads to an increase in energy consumption for heating the bottom and cooling the top of the stabilization column for increasing steam and reflux numbers to compensate for the deterioration of separation efficiency. The method also requires the use of a large amount of equipment and is characterized by a high hardware intensity of hardware design.

The objective of the invention is to simplify the hardware design and reduce its metal consumption, eliminate energy costs, reduce energy costs, increase industrial safety.

The technical result that is achieved by the method:

- simplification of hardware design and reduction of its metal consumption by reducing the number of pieces of equipment,

- the exclusion of energy costs for the supply of reflux to the top of the stabilization column and for the circulation of the bottoms product through the fire heating furnace through the use of a fractionating apparatus of the film type with internal heat and mass transfer elements,

- reduction of energy consumption due to the exclusion of fire heating,

- improving industrial safety by eliminating fire heating.

The specified technical result is achieved by the fact that in the known method, comprising supplying a heated unstable hydrocarbon fraction to the middle part of the stabilization column, the upper part of which is cooled and the lower part is heated, the output of stabilization vapors from the top, and the stable hydrocarbon fraction from the bottom of the stabilization column, is a feature is that

as a stabilization column using a vertical fractionating apparatus with a falling film, including the upper and lower blocks of vertically arranged heat and mass transfer elements, and a power zone located between them,

moreover, the heat and mass transfer elements, for example, of a radial-spiral type, include profiled vertical surfaces that form the inner space for the passage of the coolant or coolant, and the outer space for countercurrent movement of liquid and steam,

the lower part of the fractionating apparatus is heated by supplying the bottom of the inner space of the heat and mass transfer elements of the lower block as a coolant to a heated unstable hydrocarbon fraction, which is removed from its top, throttled to a stabilization pressure and fed to the feed zone,

the upper part of the fractionation apparatus is cooled by supplying a refrigerant to the top of the inner space of the heat and mass transfer elements of the upper block, which is removed from its bottom,

and as stabilization vapors, stabilization gas is removed from the top of the fractionation apparatus.

Use as a stabilization column of a vertical fractionating apparatus with a falling film, including the upper and lower blocks of heat and mass transfer elements, and a feed zone located between them, using heat and mass transfer elements, for example, of a radially spiral type, with profiled vertical surfaces forming an internal space for passage coolant or coolant, and the outer space for countercurrent movement of liquid and steam, eliminates the use of the refrigerator of stabilization vapors, reflux capacity, reflux and circulation pump, due to which to simplify the hardware design and reduce its metal consumption, as well as to exclude electricity consumption for the circulation of reflux and bottoms product.

In addition, the height and metal consumption of the fractionating apparatus itself are reduced by creating favorable hydrodynamic conditions for mass transfer and preventing the cross movement of liquid and vapor due to sectioning of the internal space of the fractionating apparatus by vertically arranged heat and mass transfer elements.

Heating the lower part of the fractionating apparatus by feeding the heated unstable hydrocarbon fraction, which is removed from its top, throttled to the stabilization pressure and fed into the supply zone as a coolant, to the bottom of the inner space of the heat and mass transfer elements of the lower block allows stabilization due to the use of heat from the unstable hydrocarbon fraction and thereby exclude fire heating and reduce energy consumption for stabilization. Throttling leads to the evaporation of light components from an unstable hydrocarbon fraction, due to which the saturated vapor pressure decreases and its stabilization occurs. In addition, a fire heating furnace is excluded from the composition of the equipment, which reduces the hardware intensity of the hardware design and increases industrial safety.

Cooling the upper part of the fractionation apparatus by supplying a refrigerant to the top of the inner space of the heat and mass transfer elements of the upper block allows reducing energy consumption by eliminating the energy consumption for pumping reflux to the top of the column.

The stabilization pressure depends on the fractional composition and temperature of the unstable feedstock and is calculated based on the required fraction of the distillation of light components from the unstable feedstock and the required flash point (or saturated vapor pressure) of the stable hydrocarbon fraction.

The method is as follows (figure 1). A heated unstable hydrocarbon fraction (I) is fed to the bottom of the inner space of the lower block of the heat and mass transfer elements 1 of the fractionation apparatus 2, which is then removed (II) from its top, throttled to the stabilization pressure on the throttle valve 3 and fed to the supply zone 4. The upper part of the fractionation apparatus 2 are cooled by supplying refrigerant (III) to the top of the inner space of the upper block of heat and mass transfer elements 5. From the top of the fractionation apparatus 2, stabilization gas (IV) is discharged, and from the bottom, a stable hydrocarbon w fraction (V).

Example 1. Unstable diesel fraction of the composition: NK - 44.4 ° C, 10% vol. boils at 145.4 ° C, 50% vol. boils at 283.2 ° C, 90% vol. boils at 353.2 ° C, 98% vol. boils at 389 ° C, flash point 44.1 ° C, at a pressure of 4.0 MPa they are introduced into the bottom of the inner space of the lower block of the heat and mass transfer elements of a fractionating apparatus with a temperature of 280 ° C, they are brought out with a temperature of 252.6 ° C from the top of the tube space of the lower heat and mass transfer section, throttled to a pressure of 0.4 MPa gage. and served in the form of a vapor-liquid mixture with a mass fraction of distillation of 0.052 into the feed zone. Cooling water with a temperature of 55 ° C is supplied to the top of the inner space of the upper block of heat and mass transfer elements.

From the top of the fractionating apparatus at a temperature of 170.5 ° C, 4.7 t / h of stabilization vapors are taken, from the bottom at a temperature of 274.0 ° C, 80.3 t / h of a stable diesel fraction with a flash point of 63.4 ° C are taken.

Cold consumption amounted to 5.8 kJ / t of product, heat and electricity were not consumed.

Under the conditions of the prototype, when receiving 80.8 t / h of a stable diesel fraction with a flash point of 63.3 ° C, the cold consumption was 31.6 kJ / t of product, the heat consumption was 18.9 kJ / t of product, the estimated power consumption for reflux (net power) was 0.4 kW.

Thus, the above example shows that the proposed method allows to simplify the hardware design, reduce metal consumption, eliminate energy costs, reduce energy consumption, increase industrial safety and can be used in the oil refining industry.

Claims (1)

The method of stabilization of hydrocarbon fractions, including the supply of a heated unstable hydrocarbon fraction to the middle part of the stabilization column, the upper part of which is cooled and the lower part is heated, the output of stabilization vapors from the top, and the stable hydrocarbon fraction from the bottom of the stabilization column, characterized in that as a stabilization the columns use a vertical fractionating apparatus with a falling film, including the upper and lower blocks of vertically arranged heat and mass transfer elements, and a zone a power supply located between them, the heat and mass transfer elements, for example, of a radial-spiral type, include profiled vertical surfaces that form the inner space for the passage of the coolant or coolant, and the outer space for countercurrent movement of liquid and steam, the lower part of the fractionating apparatus is heated by feeding the bottom of the inner the space of the heat and mass transfer elements of the lower block as a heat carrier of the heated unstable hydrocarbon fraction, which is removed from of the top, is throttled to stabilize the pressure and fed into the feed zone, an upper portion of the fractionating apparatus is cooled by feeding refrigerant to the top of the inner space of the upper block element teplomassoobmennyh that is outputted from its bottom as well as stabilization of vapor from the top of the fractionating unit output gas stabilization.