Avoidance of environmental regulatory penalties through engineered wastewater cooling solution

Summers in Japan can be extremely hot with temperatures rising up to 38 ℃. A large refinery faces a recurring problem every summer – high wastewater treatment plant inlet temperature.

Effluent water from crude desalters typically gets cooled by cooling water to circa 30 ℃ before being sent to the wastewater treatment plant. However, cooling water temperature soars during summer, which inevitably causes a chain effect where wastewater temperature goes up to as high as 50 ℃.

This has a detrimental impact on the performance of the wastewater treatment plant, which functions optimally in the range of 20 – 40 ℃. The consequences could be far-reaching; beyond heavy economic losses through fines or forced shutdowns, the refinery could also be subject to scrutiny from environmental watch groups and its reputation could take a hit.

The process engineer of the refinery recalled of a discussion with Aggreko’s local team on our suite of process enhancement and risk management solutions for refineries, and decided to approach Aggreko to see if we were capable of resolving this pressing problem.

Aggreko Process Services designed a bespoke cooling system that’s capable of effectively cool and maintain the temperature of effluent wastewater at a flow rate of 120m³/hour to <40 ℃ through a combination of a compact portable cooling tower and plate heat exchanger in a closed loop.

Aggreko’s portable GT20 cooling tower is an integral component of the solution.  Through rigorous discussions, site visits and modelling computations, the portable cooling tower’s energy efficiency surpasses that of a competitive project design comprising of industrial chillers. 

In addition, the GT20 cooling tower takes up a mere 14.7m², while the industrial chillers would have taken up almost 176.4m². This is critical as plot space was a constraint for the customer. With increased urgency to resolve the pressing issue, Aggreko responded swiftly by commissioning the integrated solution within 4 days of project sign-off, a testament to our team’s customer-focused commitment.

During the operational phase, Aggreko assisted in the monitoring of the heat exchanger’s pressure drop and wastewater temperature to ensure that everything was running smoothly. The automated solution also provided control of the water make-up and blow-down.

The customised wastewater cooling solution delivered consistent reduced wastewater treatment plant inlet temperatures of under 40⁰c throughout the project tenure which lasted 2 months during the hottest months of the year.

The solution helped the refinery avoid violation of environmental regulations and uphold its reputation as a responsible corporation as part of the local community.

The successful project delivery instilled great confidence on Aggreko’s solutions within the organisation which led to the customer agreeing to replicate the deployment of this temporary cooling solution for next year’s summer season.