Examination of the Reasons for the Formation of Red Oil in Spent Caustic from Olefin Plant

Authors: Mehdi Seifollahi, Ashkan Forootan, Sajjad Bahrami Reyhan

Abstract:

Due to the complexity of olefinic plants, various environmental pollutants exist such as NO_x, CO₂, Tar Water, and most importantly Spent Caustic. In this paper, instead of investigating ways of treating this pollutant, we evaluated the production in relation to plant’s variable items. We primarily discussed the factors affecting the quality of the output spent caustic such as impurities in the feed of olefin plant, the amount of injected dimethyl disulfide (DMDS) in furnaces, variation in feed composition, differences among gas temperatures and the concentration of caustic solution at the bottom of the tower. The results of the laboratory proved that in the formation of Red Oil, 1,3butadiene and acetaldehyde followed free radical and aldol condensation mechanism respectively. By increasing the injection rate of DMDS, Mercaptide amount increases in the effluent. In addition, pyrolysis gasoline accumulation is directly related to caustic concentration in the tower. Increasing naphtenes in the liquid feed augments the amount of 1,3butadiene, as one of the sources of Red Oil formation. By increasing the oxygenated compound in the feed, the rate of acetaldehyde formation, as the main source of Red Oil formation, increases.

Keywords: Olefin, spent caustic, red oil, caustic wash tower.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1130381

References:

[1] Nowowiejski, G., J.A.R.o. Stone, and Webster. An Overview of Oxygenates in Olefines Units In Relation to Corrosion, Fouling, Products Specifications and Safety. In American Institute of Chemical Engineers. (2003) Neworlean.
[2] Maugans, C., M. Howdeshell, and S.D. Haan. The Effect of Caustic Tower Operation and Spent Caustic Handling on TheZimpro Wet Air Oxidation (WAO) of Ethylene Spent Caustic. In Ethylene Producer’s Conference. (2009) Tampla,FL.
[3] Ellis, C.E., R.J. Lawson, and B.L. Brandenburg. Wet Air Oxidation of Ethylene Plant Spent Caustic. In Sixth Annual Ethylene Producers Conference. (1994) Atlanta, Georgia, USA.
[4] Maugans, B.K.C.F.C. Wet Air Oxidation Treatment of Spent Caustic in Petroleum Refineries. In National Petroleum Refiners Association Conference. (2010)
[5] Sheu, S.-H. And H.-S. Weng, Treatment of Olefin Plant Spent Caustic by Combination of Neutralization & Fenton Reaction. PERGAMAN, Elsevier, Wet. Res, (2000) 35
[6] J.F.Martin, Ethylene Plant Process Treatment Technology. Betz Dearborn HPG, Woodlands, Texas, (1998)
[7] Olefin Complex Cracking Plant Operating Manual. 0 ed.
[8] C.Maugans and M.Howdeshell, Update: Spent Caustic Treatment. Hydrocarbon Processing, (2010)
[9] Foret, F., A Radical Approach to Treat Petrochemical Wastewater.
[10] Foret, F., Spent Caustic Treatment with OHP Wet Peroxide Oxidation.
[11] Gondolf, J.M. and S.A. Krukchi. Spent Caustic Treatment: The Merits of Pretreatment Technology Applications for the Refinery/Petrochemical Industries. In Eleventh Ethylene Forum (1997). Woodlands, Texas, USA.
[12] Blaschke, M.W. and B. Petrolite, Cause and Remedies in Caustic Tower Fouling. PTQ Magazine (2003)
[13] Blaschke, M.W. and B. Petrolite. Caustic Tower Fouling: Identifying the Cause. inAIChE Ethylene Producers Conference. (2003) Sugar Land, Texas.
[14] Claud E. Ellis & Robert J. Lawson & Baucel L. Brandenburg, Wet Air Oxidation of Ethylene Plant Spent Caustic, Presented at Sixth Annual Ethylene Producers Conference, (1994) , Atlanta, Georgia, USA.
[15] Caustic Tower Treatment Monitoring: Fouling Cause and Characteristics. (2007) Energy Chemical
[16] Mullenix, D., et al. Control of Carbonyl Polymer Fouling In Caustic Tower. In AIChE Spring National Meeting & Eighth Annual Ethylene Producer's Conference. (1996) New Orleans. Louisiana.