WO1992001033A1

WO1992001033A1 - Process for demetalizing oils

Info

Publication number: WO1992001033A1
Application number: PCT/GB1991/001012
Authority: WO
Inventors: Misha Friedman; Giora Honig
Original assignee: Freed, Arthur, Woolf
Priority date: 1990-07-04
Filing date: 1991-06-21
Publication date: 1992-01-23
Also published as: AU8074191A; PT94582A; ZA913884B

Abstract

The present invention relates to a process for demetalizing oils which comprises heating oil to be demetalized, heating a diluted aqueous ammonium hydrogen sulfate solution containing oxalic acid, adding ethoxynonane while a temperature of at least 80 °C is maintained, thoroughly mixing and separating while the system is maintained at a temperature higher than 80 °C.

Description

PROCESS FOR DEMETALIZING OILS S P E C I F I C A T I O N

The present invention relates to a process for

demetalizing oils and which is based on the reaction of the oil to be demetalized and an aqueous diluted

ammonium hydrogen sulfate solution containing oxalic acid to which ethoxynonane is added.

More particularly, the process according to the present invention comprises the characterizing steps as follows of: a) heating the oil to be demetalized to a temperature Of from 70ºC to 130ºC; b) heating an aqueous solution containing 3 to 6 per cent in weight of ammonium hydrogen sulfate and 1 to 5 per cent in weight of oxalic acid to a temperature higher than 70ºC; c) adding ethoxynonane heated to a minimal temperature of 80ºC to the solution b); d) intensive mixing of the oil obtained in a) and the heated solution obtained in c) and separating the phase while the system is maintained at a

temperature higher than 80ºC.

Table 1 shows the main properties of an oil before being treated by the process according to this invention, and of the finished product.

TABLE I

Used Oil Treated Oil

Volume (%) 100 89

Water (% in weight) 7,2 -

Diluent (% in volume) 3,6 -

Ashes (% in weight) 1,28 0,06

Lead (p. p. m. ) 4828 11

Viscosity Index - 101

Charbon Ramsboton

(% in weight) 2,55 0,89

Quality of the Obtained Product

The demetalization does not modify the characteristics of the treated oil excepting the decrease of its metal content and therefore its ash content. According to an experimental run with approximately 50, 000 litres of oil containing about 3000 ppm of lead and about 1, 5% in weight of ashes, a treated oil having the properties as shown on Table II was obtained.

TABLE II

Viscosity at 37,8ºC (100ºF) 631 SUS

Viscosity at 98,8ºC (200ºF) 74, 8 SUS

Viscosity index 111

Acid number 1,14

Base number 0,0

Ashes (%) 0,6)

Metals, ppm

Lead 80

Zinc 2

Iron 10

Nickel 1

Copper 7

Chromium 12

Vanadium 1

The treated oil is of a dark reddish colour and it is clear when viewed through thin layers. It is equivalent to a high quality heavy fuel oil because its sulphur content is lower than 1% and does not contain any asphaltic component. Due to its stronger paraffinic nature when compared with the heavy fuel oils, its heating power is 3 to 5% higher.

Subsequent Treatment

Alternatives

After the chemical treatment, the treated oil contains water (generally less than 1%), light

components/solvents and also a small amount of a

dispersed precipitate and all the additives under the acid form. The subsequent treatment comprises several steps carried out sequentially or according to different combinations: sedimentation, stripping with stream, caustic extraction, and filtration.

For the sedimentation, a settling vessel is used, a residence time of at least 24 hours being recommended. As it is convenient to keep a high temperature, the settling vessel must be provided with a heating jacket.

The main purpose of the stripping step is the removal of the residual water and light components/solvents. The treated oil must be heated previously at 110-120ºC and 30 to 40 kg of steam by metric ton of treated oil must be injected. The success of the stripping step can be checked measuring the flash point of the oil after the treatment, which must be a minimum value of 60ºC if it will be used as a fuel oil.

If a continuous operation is carried out, the oil after being stripped can be pumped through heating coils located inside the settling vessel so that it provides the necessary heat.

For removing the acidic components, the oil must be extracted with a caustic soda solution. Afterwards, the oil must be separated from the treatment solution. This separation is made on a settler, a time of residence of 2 to 3 hours being sufficient.

For the extraction, a 2% aqueous caustic soda solution is used and a ratio of caustic solution and oil of 1:4 is preferred.

If the treated oil is to be used as a fuel oil, its maximum content of sodium is 15 ppm, and therefore it must be washed with water containing 0, 5% in weight of sulfuric acid.

The filtration is the best way for removing the residual precipitate from the treated oil. However, treated oils are very difficult to filter due to the small size of the precipitate particles (under 1 micron). The Applicant found that through a heating step from 130 to 140ºC, the precipitate coagulates and the filtration of the oil becomes rather easy. The dimensions of the heating vessel must provide a residence time of about 1 hour.

Claims

Claim

Process for demetalizing oils, characterized in that it comprises the steps of a) heating the oil to be demetalized to a temperature of from 70ºC to 130ºC; b) heating an aqueous solution containing 3 to 6% in weight of ammonium hydrogen sulfate and 1 to 5% in weight of oxalic acid to a higher temperature than 70ºC; c) adding to the solution b) ethoxynonane previously heated to a minimal temperature of 80ºC; d) intensive mixing of the oil obtained in step a) and the solution obtained in step c) and separating the phases while the system is maintained at a higher temperature than 80ºC and e) subsequently treating the oily phase by settling, stripping, caustic extraction and filtration.