Chevron Chemical Company

Year Submitted: 2003

Process: Cleaning with Wash Oil

Industry: Chemical Manufacturing

Wastes Reduced: Benzene

Substance: Contaminated Coke Sludge

Location: Cedar Bayou Plant, Baytown TX

No. of employees: 960

Contact: Joe Ross

Phone: (713) 421-6559

Description:

Chevron Chemical Company operates an ethylene unit at its Cedar Bayou plant in Baytown. A by-product of the cracking process in this unit is coke, which gets carried over from the furnaces into the gasoline fractionator, and into the bottom stream (quench oil). It is removed from the quench oil via filtration. The filters are cleaned weekly. They are first flushed with a wash oil to remove heavy hydrocarbons, which are recycled to the process. The remaining coke sludge becomes a process waste. The coke was characteristically hazardous due to benzene.Because the conditions at which the gasoline fractionator is operated should prohibit benzene from being in the coke sludge, Chevron Technical and Operations personnel investigated the source of the benzene in an effort to remove it. It was discovered that the wash oil being used was off-specification heavy aromatic distillate (HAD), another by-product of the process. During startup of the hydrogenated pyrolysis gas (HPG) unit, the product streams, including HAD are not within specifications.

P2 Application:

Chevron Chemical Company operates an ethylene unit at its Cedar Bayou plant in Baytown. A by-product of the cracking process in this unit is coke, which gets carried over from the furnaces into the gasoline fractionator, and into the bottom stream (quench oil). It is removed from the quench oil via filtration. The filters are cleaned weekly. They are first flushed with a wash oil to remove heavy hydrocarbons, which are recycled to the process. The remaining coke sludge becomes a process waste. The coke was characteristically hazardous due to benzene. Because the conditions at which the gasoline fractionator is operated should prohibit benzene from being in the coke sludge, Chevron Technical and Operations personnel investigated the source of the benzene in an effort to remove it. It was discovered that the wash oil being used was off-specification heavy aromatic distillate (HAD), another by-product of the process. During startup of the hydrogenated pyrolysis gas (HPG) unit, the product streams, including HAD are not within specifications

Environmental Benefits:

This process produced 146 tons of hazardous waste in 1994. As a result of this change, the waste is no longer classified as a hazardous waste.

Details of Reductions

Additional Information :

Since the material is now handled as a Class 1 nonhazardous waste Chevron saves an estimated $160,000 a year in disposal and regulatory costs.

Source: TCEQ