BACKGROUND

A major US conglomerate ships petroleum coke throughout the Pacific Rim. A unique feature of their ship loading facility is the capability to blend various coke products. In order for this blending process to work properly, high capacity belt conveyors and associated chutes must perform flawlessly. Speed is important, since the facility is capable of loading blended coke into a bulk container ship at 2,000 tons per hour. Delays in the loading operation created by flow stoppages can disrupt schedules, leading to higher shipping costs.

THE PROBLEM

The facility encountered severe plugging problems with the chute system that feeds into their main storage silos. These stoppages occurred in several chutes at conveyor transfer points. Fine coke particles built up on interior surfaces of the chutes until flow stopped. These unpredictable stoppages would occur when the chute outlet cross-section was reduced by as little as 10%. The water used in cleanups ended up in the silos, which increased the moisture content of the stored coke and thus created additional clean-up problems downstream.

A tripper car chute in the ship loading system also experienced similar problems. Blockages at this location, where flow rates at times reach 2,000 tons per hour, sometimes halted ship-loading operations for an entire shift.

THE SOLUTION

Jenike & Johanson engineers designed and built new transfer chutes to replace most of the faulty chutes. The first step was to determine the coke flow properties, including the minimum chute angles. We ran model tests to identify a chute wall material that would resist the effects of adhesion, and verify minimum chute angles. Rectangular box chutes were replaced with new, steeper chutes having circular cross-sections with special surface finishes. Jenike & Johanson supervised the fabrication of the chutes and provided a performance warranty.

THE RESULT

The petroleum coke handling system has been in operation for over three years with minimal downtime for maintenance. According to the plant operations manager, "Maintenance costs have been reduced and handling improved significantly by installing the new system.

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