Refinery Coker Pit Water Blasting

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Refining - Coker Pit Water Blasting
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A refining customer approached Veolia to develop a better way to clean the screens that separate coke fines generated in the refinery's coking process from the water to be recycled in their hydraulic coke cutting system. The customer wanted to find a safe, efficient, reliable and cost effective way to the manual cleaning method that uses a fire hose attached to a crane bucket to wash the screens from a distance of 75 feet below the water's surface in the pit. 

The screens are very small, measuring 2' x 7' and are recessed 2' from the edge of the concrete wall that they are housed in. Moderating the effects of the nozzle backthrust in the pit's underwater environment along the X axis of the cleaning tool was a significant logistical challenge that Veolia needed to overcome. Veolia needed to position the nozzle of their custom tooling close enough to the opening set in the weir wall to effectively remove the coke fines and residue obstructing the entire grating surface of the screens. 


Veolia proposed combining their new water blasting tool, the pit's overhead crane bucket, and new technologies and safety mechanisms to ensure the methodology is safe, efficient and cost-effective. Veolia engineered an XY Track for the crane's bucket using a simple bolting grid, making installation a quick and easy two-man operation. Once installed, the XY Track allows for remotely controlled speed and direction adjustments of the water blasting nozzle along the X- and Y-axes to achieve complete cleaning coverage of the screen's surface area. 

Unlike previous methods, Veolia will be able to verify progress of the submerged cleaning process by fitting the nozzle's head with a waterproof Generation-4 infrared video camera. This technology provides the operator with the ability to see and record exactly what is going on below the surface and make directional adjustments to the cleaning head to maximize the efficiency of the cleaning operation.

Because there will be variable forces exerted on the XY Track due to the backthrust of the cleaning head as it travels along the X-axis, Veolia needed to provide a counterbalance mechanism to ensure stability and overall reliability of the  tooling. To accomplish this task, two outriggers have been designed to be installed on the back of the XY Track to maintain a proper cleaning distance from the screen's surface, ultimately providing precise remote operation of the tooling. The entire operation is powered by a single 1,000 HP pump and can be managed by two technicians. 


Veolia's new technology and innovative methodology will remove coke fines and residue from the screens, increasing the efficiency of the coker unit by decreasing the amount of coke that can pass through the jet water pump in the hydrocutting process. Increasing cleaning effectiveness will extend the life of the coker pump and reduce costly downtime. 

The improved cleaning results derived from this fully automated process will also reduce the cleaning frequency that the screens will require - from daily to quarterly - while recovering more water that can be recycled through the hydrocutting process. This methodology will ultimately reduce the plant's overall water resource requirements. Reduction in maintenance costs, extending the life of the pump, and increasing water sustainability all deliver cost savings and added value. 

Veolia developed a proposal to clean four sets of screens located 75' below the water level of the refinery's coker pit using a custom-designed water blasting tool that attaches directly to the existing bridge crane to remotely clean the pit's weir system and increase the overall efficiency of the entire unit. 
-Daniel Black, Veolia Account Manager