CN1083850A - Electric desalting process for mixed residual oil - Google Patents

Abstract

The process provided by the present invention comprises two-stage electric desalting, electric field is applied to both the first stage and the second stage, demulsifier and washing water are injected into the first stage, the process conditions are electric field strength of 0.08-1.2KV/ ^cm2 , desalting temperature of 120-145℃; operating pressure of 0.3-0.8MPa, purified water can be injected, pH of 5-9, and the water injection amount is 5-15% (wt%); mixing intensity is 0.05-0.20MPa; demulsifier SN2040 or Sh811, the injection amount is 20-50ppm, the strong electric field residence time is 3-6min, for the electric desalting of residual oil with a temperature of more than 350℃, the total desalting rate can reach more than 90%, for the catalytic cracking unit of the refinery, salt formation of the distillation tower tray can be avoided when the residual oil is blended, catalyst poisoning is reduced, and the production cycle of the catalytic cracking unit is extended.

Description

The invention belongs to the field of petroleum processing, and in particular relates to a residual oil electric desalination process.

As we all know, in the process of petroleum refining, the catalytic cracking unit generally needs to blend the residual oil, and the salt content of the residual oil is relatively high, usually 5-30 mg/l. Due to the high salt content, the fractionation column of the catalytic cracking unit is often caused by salt formation. The pollution and poisoning of the catalyst shorten the service life of the catalyst and increase the production cost. Therefore, any oil refinery production unit that blends refining residue should desalt the residue with high salt content before the residue enters the catalytic cracking unit. Judging from the literature reports, there are desalination/dehydration of heavy asphalt oil used in oilfields; demulsification to remove asphaltenes and recover deasphalted oil, asphaltenes and emulsified water respectively; oily sludge dehydration process; tar emulsion thermal method Dehydration and multi-stage desalination and dehydration process of crude oil, there is no detailed report on residual oil electric desalination process.

The purpose of the present invention is to use the existing electric desalting device to use SH811 or SN22040 demulsifier in the process to make the desalination rate of residual oil reach more than 90%, prolong the production cycle of the catalytic cracking device and reduce the production cost.

Accompanying drawing 1. is the process flow diagram of electric desalination of mixed residual oil.

A ₁ residual oil

A ₂ Residual oil after desalination

A ₃ water

A ₄ Demulsifier

V ₁ residual oil storage tank

V ₂ residual oil heating tank

V _3-5 residual oil electric desalination tank

B ₁ residual oil pump

B ₂ water injection pump

B ₃ injection pump

P _1-6 pressure gauge

T _1-4 Thermometer

The present invention is shown in Figure 1: the residual oil (A ₁ ) in the storage tank _V1 is pumped out by the residual oil pump _B1 to the heating tank _V2 , and then enters the electric desalination tank _V3 , and injects washing water and demulsifier before entering _V3 , after the first-stage electric desalting, the residual oil enters the V ₄ second-stage electric desalting tank, and if necessary, enters the third-stage electric desalting tank (V ₅ ), and then the desalted residual oil is replaced with the pre-desalted residual oil in V ₁ Heat out device.

Electric field strength of primary, secondary or tertiary electric desalination tank:

0.08-1.2KV/ ^cm2

Desalination temperature: 120-145°C

Operating pressure: 0.3-0.8MPa

Injection water quality: purified water, PH5-9

Water injection volume: 5-15%

Mixing intensity: 0.05-0.20MPa (that is, the pressure difference between the front and rear of the mixer, also known as multi-mixing pressure difference)

Demulsifier model SN22040 (commercially available)

Its quality is: the hydroxyl value is not more than 56.00mgKOH/g

Chromaticity is not more than 300

Freezing point is 25～50℃

Demulsifier model SH811 (commercially available)

Its quality is: hydroxyl value ≤ 56.00mgKOH/g

Uniform and transparent appearance: the solubility is water-soluble without floc.

Demulsifier injection amount is 20-50ppm

The residence time of the strong electric field is 3 to 6 minutes;

SH811 is used for residual oil above 350℃, and the total desalination rate can reach more than 90%.

The present invention uses the commercially available demulsifier SN22040 or SH811 to make the total desalination rate of >350°C residual oil up to about 90%, and provides the most suitable demulsifier and optimized process conditions for the electrical desalination of residual oil, thereby avoiding catalytic desalination. Cracking fractionator tray salt buildup and mitigation of catalyst poisoning.

Example 1

Atmospheric residual oil is mixed with the residual oil, and injected into V ₂ through B ₁ at a treatment rate of 10 liters/hour, and the temperature rises to 120-145°C into the desalination tank V ₃ , and the demulsifier SN22040 is applied, with an injection rate of 20-50 ppm. Injection water quality Purified water PH5-9, injection volume 5-15% (wt%), mixing pressure difference 0.05-0.2MPa, electric field strength 0.8-1.2KV/cm ² , strong electric field residence time 3-6min, secondary desalination effect See Table 1.

Table 1 Residual oil salt content mg/L Salt rejection % Total rejection rate Moisture % Take off the front take off two off take off two off % level one Secondary 11.95 8.32 1.19 30.4 85.7 90.0 3.00 1.80

Example 2

After the residual oil at atmospheric pressure is mixed with the residual oil, the treatment capacity is 10 liters per hour, and the combination is optimized with the process conditions of Example 1. After two-stage desalination, the total desalination rate is above 90%, see Table 2:

Example 3

Atmospheric residual oil is mixed with residual oil, with a treatment capacity of 10 liters per hour, injected into tank V ₂ with B ₁ , the temperature rises to 120-145°C and fed into desalination tanks V ₃ and V ₄ , and the commercially available demulsifier SH811 is used. The injection volume is 20-50ppm, the injection water quality is PH5-9, the injection volume is 5-15% (wt), the mixing pressure difference is 0.05-0.2MPa, the electric field strength is 0.8-1.2KV/cm ² , and the strong electric field residence time is 3-6min , the secondary desalination effect is shown in Table 3:

Example 4

Atmospheric residual oil is mixed with residual oil, and the treatment capacity is 10 liters per hour. The process conditions of Example 3 are used to optimize the combination. After two-stage desalination, the total desalination rate is above 90%. The results are shown in Table 4:

Claims (2)

1. An electric desalination process using demulsifier SN22040 or Sh811, which is characterized in that it is used for electric desalination of residual oil. The residual oil in the storage tank _V1 is pumped out by the residual oil pump _B1 to heat the tank _V2 , and then into the electric desalination tank _V3 . The desalination tank is injected with washing water and demulsifier before entering the tank. After the first-level electric desalination, the residual oil enters the V ₄ second-level electric desalination tank or, if necessary, the third-level desalination tank V ₅ , and then the desalted residual oil exits the device. 2. The electrical desalting process of residual oil according to claim 1, characterized by process conditions: electric field strength: 0.08-1.2KV/cm ² ; desalination temperature: 120-145°C; operating pressure: 0.3-0.8Mpa; water injection Water quality: PH5-9 purified water; water injection volume: 5-15% (wt%); mixing intensity: 0.05-0.20Mpa; demulsifier injection volume: 20-50ppm; strong electric field residence time: 3-6min.

Images