Testing of Selected Demulsifiers for Desalting and Dehydration of Typical Crude Oil from the Tomsk Petrochemical Plant
Abstract Generated abstract
This paper evaluates selected demulsifiers for desalting and dehydration of typical crude oil from the Tomsk Petrochemical Plant, emphasizing the need for laboratory selection because demulsifier performance depends on crude composition and treatment conditions. Domestic reagents OZhK and KAUFE-14 and imported demulsifier 4411 were tested using thermochemical treatment at 60°C and electrical desalting at 6 kV, with residual water and salt contents measured after settling. OZhK gave practical results at 30 to 40 g/t with 10% wash water, while electrical desalting with OZhK reduced salt content to about 14 to 15 mg/l and removed water to absent or trace levels. Demulsifier 4411 was somewhat more effective under comparable conditions, but its cost and limited availability were noted, whereas KAUFE-14 showed low effectiveness for this crude.
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TESTING OF SOME DEMULSIFIERS FOR DESALTING AND DEHYDRATION OF TYPICAL CRUDE OIL FROM THE TOMSK PETROCHEMICAL PLANT
K. K. STRAMKOVSKAYA, G. I. KRAVTSOVA, G. B. NEMIROVSKAYA,
A. A. DYACHENKO, L. S. ZHURAVLEVA
(Submitted by the scientific-methodological seminar of the organic departments
of the Faculty of Chemical Technology)
At present, a fairly large number of surface-active substances are known that are used as demulsifiers for breaking petroleum emulsions. Many studies [1—6] have shown that demulsifiers, in terms of the degree of desalting and dehydration, exhibit selective action depending on the composition and quality of the crudes, the temperature conditions of treatment, etc. This determines the need to conduct preliminary laboratory tests for each crude oil in order to identify the most effective demulsifiers before recommending them for plant conditions.
We tested domestic demulsifiers of industrial importance—OZhK, KAUFE-14—and the imported demulsifier 4411.
Desalting was carried out by the thermochemical method and in a high-voltage field.
The procedure for thermochemical desalting is as follows: distilled water in an amount of up to 10% by weight is added to 300 ml of crude oil and mixed for five minutes with a stirrer at 400 rpm. Then the demulsifier* is added, and the sample is again mixed for five minutes. The resulting emulsion is allowed to settle in a separatory funnel in a thermostat for 4 hours at a temperature of 60°C. The separated water is removed from the oil every hour and measured. With the last portion of water, about 10% of the lower oil layer is drained off.
In the oil thus prepared, the water content was determined by the Dean–Stark method, and the salt content according to GOST 10097-62.
Electrodesalting was carried out at a voltage of 6 kV in a metal beaker 70 mm in diameter and 100 mm high for 10 minutes. The walls of the beaker served as one electrode, and the second was a steel rod 10 mm in diameter installed at the center. After electrical treatment, the emulsified oil was poured into a separatory funnel, allowed to settle for 4 hours at 60°C, and then analyzed for the content of salts and water in the upper layer.
The research results presented in the table show that good results in the desalting and dehydration of typical crude oil can be obtained when using OZhK in an amount of 30—40 g/t. The degree of desalting and dehydration depends, first of all,
* The demulsifier was used in the form of an aqueous solution with a concentration of 2 g/l.
in turn, on the initial content of salts and water in the oil. Thus, at a salt content of 505 mg/l of oil, thermochemical treatment makes it possible to desalt the oil by 91.1%; at salt contents of 775 and 1438 mg/l, only by 57.7 and 69.3%. Increasing the demulsifier consumption above 40 g/t only slightly reduces the residual salt content, leaving it fairly high (35–51 mg/l). The use of a high-voltage field makes it possible to obtain oil with a salt content of 14 mg/l at an OZhK consumption of 20 g/t and 10% wash water.
Table
Results of desalting and dehydration of oil
| No. | Initial oil: salt, mg/l | Initial oil: water, % | Demulsifier | Amount of demulsifier, g/t | Content after desalting: salts, mg/l | Content after desalting: water, % | Removed: salts, % | Removed: water, % of initial |
|---|---|---|---|---|---|---|---|---|
| Thermochemical desalting at 60°C | ||||||||
| 1 | 505 | 3.26 | OZhK | 20 | 45.0 | 0.25 | 91.1 | 92.4 |
| 2 | 1438 | 5.20 | ” | 20 | 441.0 | 1.90 | 69.3 | 63.2 |
| 3 | 775 | 4.00 | ” | 20 | 327.9 | 1.85 | 57.7 | 53.8 |
| 4 | 505 | 3.26 | ” | 30 | 35.6 | 0.54 | 93.0 | 83.4 |
| 5 | 1438 | 5.20 | ” | 30 | 441.0 | 1.95 | 69.4 | 62.5 |
| 6 | 775 | 4.00 | ” | 30 | 170.5 | 1.00 | 78.0 | 75.0 |
| 7 | 775 | 4.00 | ” | 40 | 59.6 | 0.42 | 92.3 | 89.5 |
| 8 | 775 | 4.00 | ” | 50 | 51.6 | 0.42 | 93.5 | 89.5 |
| 9 | 505 | 3.26 | without demulsifier | 0 | 147.0 | 1.19 | 70.9 | 63.5 |
| 10 | 1108 | 4.60 | KAUFE-14 | 30 | 1066.0 | 4.00 | 4.0 | 12.8 |
| 11 | 775 | 4.00 | 4411 | 30 | 95.7 | 0.60 | 87.8 | 85.0 |
| Electrical desalting at a voltage of 6 kV | ||||||||
| 12 | 770 | 4.03 | OZhK | 20 | 14.0 | absent | 98.1 | |
| 13 | 770 | 4.00 | ” | 30 | 23.4 | traces | 97.0 | |
| 14 | 770 | 4.00 | ” | 40 | 14.0 | absent | 98.1 |
Demulsifier 4411 proved somewhat more effective than OZhK; however, the higher cost and scarcity of the former substantially limit its use.
The reagent KAUFE-14 in this case proved to be of low effectiveness.
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For desalting oil from the Tomsk Petrochemical Plant, OZhK may be used.
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At an OZhK consumption of 30–40 g/t and water at 10% by weight, one-stage electrical desalting makes it possible to prepare oil to a salt content of 14–15 mg/l.
LITERATURE
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Ya. G. Sorokin, Ya. I. Nelkenbaum. On the prospects for using new demulsifiers. In: Application of surfactants in the petroleum industry. Moscow, “Neftekhimiya,” 1963.
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A. A. Petrov. Demulsifier reagents for dehydration and desalting of oil. Kuibyshev Book Publishing House, 1965.
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