RU2517703C1 - Method of producing paraffins and dewaxed oils - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method in which paraffin-containing material is mixed in steps with coolants in form of a cooled solvent and a dewaxing second step filtrate, in a multi-section vertically mounted apparatus - pulsating crystalliser. Mixing is carried out through pulsating action on the entire volume of the raw mixture filling the crystalliser, which provides back and forth movement in overflows between sections, wherein the coolants are continuously fed into the overflows. The suspension from the pulsating crystalliser is directly fed to filters where it is successively divided in two filtration steps in deoiling conditions to obtain a paraffin wax precipitate and deoiling filtrates. The filtrate from the second deoiling step is fed for diluting the suspension coming from the pulsating crystalliser into the first deoiling step. The filtrate from the first deoiling step is cooled in evaporation scraping crystallisers, followed by filtering the obtained suspension in two steps in dewaxing conditions to obtain a first dewaxing step filtrate - a solution of dewaxed oil. The filtrate from the second step, fed into the pulsating crystalliser as a coolant, and a by-product precipitate are obtained at the second dewaxing step.

EFFECT: high efficiency with respect to raw material and collection of dewaxed oil with high viscosity index.

2 dwg, 2 tbl, 2 ex

Description

The invention relates to methods for producing paraffins and dewaxed oils from petroleum paraffin-containing raw materials in a combined dewaxing-de-oiling process and can be used in the oil refining industry,

The closest solution to the technical nature and the results achieved is a method for producing dewaxed oils and hard paraffins (Chemistry and Technology of Fuels and Oils, 2000, No. 4, pp. 12-15), according to which a raw material suspension from paraffin-containing raw materials is obtained by multi-stage mixing with a cold solvent and the filtrate of the second stage of dewaxing due to the pulsating effect on the entire volume of the raw material mixture filling the vertically installed multisection apparatus - pulsation crystallizer .

This ensures the reciprocating movement of the raw material mixture in the flows between the sections with the simultaneous continuous supply of cold solvent and filtrate into these flows. The suspension obtained in a pulsating crystallizer is cooled in evaporative (ammonia or propane) scraper crystallizers to a dewaxing temperature, followed by two-stage filtration to obtain a first-stage filtrate - a solution of dewaxed oil - and a precipitate of a second stage filter. The filtrate of the second dewaxing stage is sent to the pulsation crystallizer as a refrigerant.

After dilution and raising the temperature, the precipitate of gacha of the second stage of dewaxing enters the stage of deacidification of the gacha, where it is filtered in one or two steps to obtain a precipitate of paraffin and a solution of a by-product of de-oiling filtrate.

The disadvantage of the method adopted for the prototype is that for pumping the suspension from the pulsating crystallizer through evaporative scraper crystallizers, an intermediate tank and a pump are necessary, which complicates the hardware design of the process - requires more equipment.

Pumping a suspension by a pump leads to a disruption of the crystalline structure of the solid phase formed in the pulsation crystallizer - paraffin crystals - due to their grinding due to the mechanical action of the impeller and partial melting caused by heating of the pumped suspension in the working part of the pump. This leads to a deterioration in the filtration characteristics of the suspension — a decrease in the rate of its filtration and the quality of separation of the liquid phase from the precipitate. The consequence of this is a decrease in the plant’s productivity for raw materials, a decrease in the selection of dewaxed oil and an increase in the oil content in gacha and, accordingly, in paraffin.

And to obtain paraffin of the required quality in terms of oil content, it is necessary to introduce into the process of dewaxing and de-oiling an additional amount of solvent for washing and diluting sediments at all stages of filtration, increasing the total ratio of the solvent to raw materials and, accordingly, the energy consumption for the process.

The aim of the claimed method is to reduce the amount of equipment used - simplifying the hardware design of the process, increasing the productivity of raw materials and selecting dewaxed oil with an increase in the viscosity index for a given oil content in paraffin and a decrease in the total ratio of solvent to raw materials.

This goal is achieved by the method of producing paraffins and dewaxed oils, according to which the suspension from the pulsating crystallizer is fed directly to the filters, where it is sequentially divided into two stages of filtration in the de-oiling mode to obtain a precipitate of solid paraffin and de-oiling filtrates.

The filtrate of the second stage of de-oiling is fed to dilute the suspension coming from the pulsating crystallizer to the first stage of de-oiling, and the filtrate of the first stage of de-oiling is cooled in evaporative scraper crystallizers. The resulting suspension is filtered in two stages in the dewaxing mode to obtain the filtrate of the first stage of dewaxing - a solution of dewaxed oil, the filtrate of the second stage of dewaxing, supplied to the pulsating crystallizer as a refrigerant, and the precipitate of a by-product.

An essential distinguishing feature of the proposed method is that the suspension coming from the pulsating crystallizer is filtered without additional cooling first in the two-stage de-oiling mode, and the suspension obtained after cooling the filtrate of the first de-oiling layer is filtered in the two-stage dewaxing mode. In this case, the filtrate of the second stage of de-oiling is fed to dilute the suspension coming from the pulsating crystallizer to the first stage of de-oiling, and the filtrate of the second stage of dewaxing is fed into the pulsating crystallizer as a refrigerant.

The specified distinguishing feature of the proposed technical solution determines its novelty and inventive step in comparison with the prior art. Thus, the claimed method meets the criteria of the invention of "novelty."

Analysis of the known technical solutions by the methods allows us to conclude that there are no signs in them that are similar to the essential distinguishing features of the proposed method, that is, the compliance of the proposed method with the requirements of an inventive step.

The method is as follows (see figure 1). The raffinate (1) at a temperature exceeding the melting point of paraffin in it is fed to the first section of the pulsation crystallizer (2).

The raw material is pulsed by means of a compressed inert gas (3) and mixed in a crystallizer with refrigerants - a filtrate of the second stage of dewaxing (4) and a cooled solvent (5).

The solvent used is the solvents used in the dewaxing, de-oiling and combined dewaxing-de-oiling processes: a mixture of methyl ethyl ketone (MEK) with toluene, methyl isobutyl ketone (MIBK), a mixture of methyl isobutyl ketone with toluene.

The principle of operation of the pulsating crystallizer (2), based on the pulsating mixing of the feed stream with refrigerants, is similar to the principle of operation of the crystallizer in the method adopted as a prototype.

The raw suspension (6) from the pulsation crystallizer (2) by gravity enters the feed tank of the filters of the first stage of de-oiling (not shown in Fig. 1), in which it is diluted with the filtrate of the second stage of de-oiling (7). The suspension (8) diluted by the filtrate is separated on the filters of the first stage of de-oiling (9). Next, the suspension obtained by diluting the precipitate of the first stage of de-oiling is filtered on the filters of the second stage of de-oiling (10).

A chilled solvent is used to rinse and dilute the precipitation of the de-oiling stages (11). Precipitate solid paraffins (12) is fed to the regeneration of the solvent.

The filtrate of the first de-oiling stage (13) is fed for cooling to evaporative (ammonia or propane) scraper crystallizers (14). The suspension (15) obtained in them enters the filters of the first stage of dewaxing (16).

The suspension obtained by diluting the precipitate of the first stage of dewaxing is filtered on the filters of the second stage of dewaxing (18). Chilled solvent (18) is supplied to the washing and dilution of sediments of dewaxing filters.

The sediment of the second stage of dewaxing (19) is sent to the solvent regeneration department, where a by-product of the process is obtained - a concentrate of low molecular weight paraffins of normal and isostructure mixed with oil. The filtrate of the first stage of dewaxing (20) - a solution of dewaxed oil - is fed to the solvent regeneration department.

The advantages of the proposed method are illustrated by the following examples.

Example 1 (prototype)

The raffinate obtained by purification with a selective solvent of oil vacuum distillate fr. 420-490 ° C, isolated from a mixture of West Siberian and Ukhta oils, was subjected to dewaxing and de-oiling using a mixture of methyl ethyl ketone (MEK) with toluene with a volume ratio of 60: 40% as a solvent. The main properties of the raffinate are shown in table 1, a schematic flow chart of dewaxing and de-oiling, taken as a prototype, is shown in figure 2.

Paraffin-containing raw material - raffinate - (1) at a temperature of 50 ° C is fed into the first section of the pulsation crystallizer (2). The raw material is pulsed by compressed inert gas (3) in a mold with two refrigerants — a solution of the filtrate of the second stage of dewaxing (4) and a cooled solvent (5). Paraffin suspension (6) from a pulsating crystallizer (2) by gravity enters an intermediate tank (7) from where it is pumped (8) to evaporative (ammonia or propane) scraper crystallizers (9), where it is cooled to the filtering temperature in the first stage of dewaxing.

The resulting suspension (10) is subjected to separation on the filters of the first and second stages of dewaxing (11), (12), where the precipitation is washed with a cooled solvent (13). Precipitation after the first and second stage of dewaxing is diluted with a chilled solvent (14). The solution of the filtrate of the first stage of dewaxing (15) enters the solvent regeneration section, where dewaxed oil is obtained. The solution of the filtrate of the second stage of dewaxing (4) is sent to the pulsating crystallizer as a refrigerant.

The dilution of the slag diluted with solvent from the second stage of dewaxing (16) enters the filters of the de-oiling stage (17), in which the precipitation is washed with a cooled solvent (14).

From the filters (17), a solution of de-oiling filtrate (18) and a paraffin precipitate (19) are discharged to the solvent regeneration.

Table 2 shows the parameters of the technological regime, quality indicators of the products and a list of basic equipment.

Example 2

As raw materials used raffinate according to example 1.

In accordance with the scheme shown in figure 1, the raffinate (1) at a temperature of 50 ° C is fed into the first section of the pulsation crystallizer (2).

The raw material is pulsed by means of compressed inert gas (3) and mixed in a crystallizer with refrigerants - a filtrate of the second stage of dewaxing (4) and a cooled solvent (5) - a mixture of methyl ethyl ketone (MEK) with toluene with a volume ratio of 60: 40%.

The raw suspension (6) from the pulsation crystallizer (2) by gravity enters the feed tank of the filters of the first stage of de-oiling (not shown in Fig. 1), in which it is diluted with the filtrate of the second stage of de-oiling (7). The suspension (8) diluted by the filtrate is separated on the filters of the first stage of de-oiling (9). Next, the suspension obtained by diluting the precipitate of the first stage of de-oiling is filtered on the filters of the second de-oiling (10).

A chilled solvent is used to rinse and dilute the precipitation of the de-oiling stages (11). Precipitate solid paraffins (12) is fed to the regeneration of the solvent.

The filtrate of the first de-oiling stage (13) is fed for cooling to evaporative (ammonia or propane) scraper crystallizers (14). The suspension (15) obtained in them enters the filters of the first stage of dewaxing (16).

The suspension obtained by diluting the precipitate of the first stage of dewaxing is filtered on the filters of the second dewaxing (17). Chilled solvent (18) is supplied to the washing and dilution of sediments of dewaxing filters.

The sediment of the second stage of dewaxing (19) is sent to the solvent regeneration department, where a by-product of the process is obtained - a concentrate of low molecular weight paraffins of normal and isostructure mixed with oil. The filtrate of the first stage of dewaxing (20) - a solution of dewaxed oil - is fed to the solvent regeneration department.

Table 2 shows the parameters of the technological regime, quality indicators of the products and a list of basic equipment.

A comparison of the indicators given in table 2, allows to draw the following conclusions - the implementation of the proposed method provides the following advantages:

one). Increase in raw material productivity from 18 to 24 m ³ / h (by 33%).

2). With a decrease in the total volume factor of the solvent to the feedstock from 4.27: 1 to 4.13: 1 (with a corresponding reduction in specific energy consumption) and comparable withdrawals of dewaxed oil and paraffin, the daily output of the target product will increase:

- dewaxed oil with a pour point of not higher than minus 15 ^o C - 88.8 tons;

- paraffin with an oil content of up to 3% wt. with a melting point of 65 ^o C - by 14.4 tons

3). Instead of de-oiling filtrate, a concentrate of isostructure paraffins and low molecular weight paraffins of a normal structure — soft paraffins with an oil content of 7.3% wt. when it is selected, close to the output of the oil filtrate filtrate.

four). An increase in the selectivity and clarity of the separation of paraffins during separate crystallization contributes to a higher selection of low molecular weight isoparaffin hydrocarbons in dewaxed oil (instead of de-oiling filtrate), which leads to an increase in the viscosity index by 2 points.

In addition, the intermediate tank and the pump for feeding the suspension from the pulsation crystallizer to the evaporative scraper crystallizers are excluded from the circuit, there is no need to install additional filters and other equipment (pumps, tanks, etc.) - only re-equipment of existing equipment is required, according to the scheme provided by the proposed way.

Table 1 The main physical and chemical indicators of the quality of raw materials - raffinate fr. 420-490 ° C The name of indicators The value of indicators Density at 20 ° C, kg / m ³ 871 Melting point, ° C +42 The paraffin content,% wt. eighteen Refractive index 1.4750 Kinematic viscosity at 100 ° С, mm ² / s 7.4

table 2 Indicators of the technological regime and the results of the combined process for the production of oils and paraffins in the processing of raffinate fr. 420-490 ° C mixture of West Siberian and Ukhta oils The name of indicators Indicator values when applying the method taken as a prototype when applying the proposed method Productivity of the plant in raw materials, m ³ / h: eighteen 24 The temperature of the raw material at the entrance to the pulsating crystallizer, ^o C fifty fifty The amount of filtrate of the second stage of dewaxing and solvent supplied to the pulsation crystallizer, m ³ / h / volume ratio to the feed: - solvent 20 / (1.11: 1) 35 / 1.45 - filtrate of the second stage 24-28 / (1.67: 1) 15 / 0.63: 1 The temperature of the suspension at the outlet of the pulsation crystallizer, ^o C 8.6 5.8 The amount of filtrate of the second stage of de-oiling supplied to dilute the suspension exiting the pulsation crystallizer, m ³ / h / volume ratio to the feed --- 29 / 1.21 Dilution of raw materials before the first stage of de-oiling, m ³ / h / volume ratio to raw materials - solvent, filtrate of the second stage of dewaxing 50 / 2.78 - solvent, filtrate of the second stage of dewaxing and second stage of de-oiling 79 / 3.29 The amount of suspension entering the first stage of filtration (dewaxing or de-oiling), m ³ / h 68 103 Filtration Temperature, ^o C: 1st stage dewaxing Minus (22-28) Minus (22-28) 2nd stage dewaxing Minus (4-6) Minus (20-25) 1st stage de-oiling Plus (5-6) Plus (5-6) 2nd stage oil decontamination --- Plus (5-6)

The name of indicators Indicator values when applying the method taken as a prototype when applying the proposed method Quantity, m ³ / h - filtrate 1 stage dewaxing 72.3 109.7 - paraffin sediment 7.7 8.4 - sediment concentrate soft paraffins --- 4.8 - oil filtrate 15.1 --- The total amount of solvent supplied to crystallization and filtration, m ³ / h / volume ratio to raw materials 77 / 4.27 99 / 4.13 Yield,% wt .: - dewaxed oil 76.3 77.1 - paraffin 17.4 16.9 - oil filtrate 6.3 --- - soft paraffin concentrate --- 6.0 The oil content,% wt. - in paraffin 2,5 2.9 - in soft paraffin concentrate --- 7.3 Production output, t / h / t / day: - dewaxed oil 10.8 / 259.2 14.5 / 348 - paraffin 2,5 / 60 3.1 / 74.4 - oil filtrate 0.9 / 21.6 --- - soft paraffin concentrate --- 1.2 / 28.8 Melting point, ^o C: - paraffin 62 65 - soft paraffin concentrate --- 37 The pour point of dewaxed oil, ^o C Minus (17-15) Minus (17-15) Dep viscosity index oils 91 93 Number of filters 7 7 including on: 1st stage dewaxing four 3 (2) 2nd stage dewaxing 2 12) 1st stage de-oiling one 2 2nd stage oil decontamination one

Claims (1)

The method of producing paraffins and dewaxed oils by stepwise mixing paraffin-containing raw materials with refrigerants, which are used as a cooled solvent and the filtrate of the second stage of dewaxing, in a multisection vertically installed apparatus - a pulsating crystallizer - due to the pulsating effect on the entire volume of the raw material mixture filling the apparatus, providing - translational movement of the raw material mixture in flows between sections, with simultaneous continuous supply to these flows refrigerants, feeding the resulting suspension to filters operating in de-oiling and dewaxing modes, regenerating the solvent from the filtration products to obtain solid paraffin, dewaxing oil and a by-product, characterized in that the suspension from the pulsating crystallizer is fed directly to the filters, where it is divided into two filtration steps in de-oiling mode to obtain a precipitate of solid paraffin and de-oiling filtrates, the filtrate of the second de-oiling step fed to the dilution of the suspension coming from the pulsating crystallizer to the first stage of de-oiling, and the filtrate of the first stage of de-oiling is cooled in evaporative scraper crystallizers with subsequent filtration of the suspension in two stages in the dewaxing mode to obtain the filtrate of the first stage of dewaxing - a solution of dewaxed oil, the filtration of the second stage supplied to the pulsating crystallizer as a refrigerant, and by-product sediment.

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