Cooling towers of vapour condensates

Cooling of vapour condensates

Cooling towers are both an environmental solution and an important development for the industry

Industry players, in particular refineries and petrochemical sites, have significant environmental challenges to address

Based in Normandy, the Total Petrochemicals France factory in Gonfreville benefits from integration with the Normandy Total refinery. The site produces the main petrochemical intermediaries (ethylene, propylene, benzene, styrene, etc.) as well as polymers (polyethylene, polypropylene and polystyrene), representing about 15% of mass-distributed plastics produced in France.

Operations managers were faced with an environmental challenge in the summer of 2010. During a period of stoppage, the petrochemical site discovered an excess of condensates after ingress of vapours from the neighbouring refinery. The excess condensates were peaking at as much as 50t/h.

What should be done with this excess?

The environmental temperature constraints did not allow the excess hot condensates to be evacuated to the natural environment. The engineers at Total Petrochemicals therefore contacted Aggreko to devise and supply a temporary cooling solution as an alternative to evacuating this excess.

Cooling Towers: An innovative solution, safe and quick to implement

Following an initial technical/economic feasibility study, the Aggreko Process Services department, dedicated to petrochemical applications, participated in an on-site Process workshop in order to evaluate the project's technical and safety expectations.

Various technical solutions were presented. With an eye on reducing the total cost of the operation and saving energy, the Aggreko engineers designed a cooling tower solution 10 times more energy efficient than traditional technologies by renting mechanical refrigeration. We therefore prioritised evaporative technology to control the 4.4 MW of thermal charge created by cooling the condensates from 100°C to 31°C.

The cooling tower solution was chosen to respond to the temporary situation during equipment downtimes, however the study did not stop there. During the study phase, Aggreko Process Engineers, working together with the Total Petrochemicals France team, proposed using "cold" condensates in the network of cooling towers on the site. Condensates are, of course, a source of recoverable water; by injecting this water into the cooling network, the condensates are recovered, lessening the environmental impact: reducing waste, water samples taken and the quantity of treatment products used.

One of the challenges for this recovery was the variable flow rate of the condensates. Variations in flow could create a risk of an excess of condensates, which is unacceptable for the environment. Together with the engineers from Total Petrochemicals, we developed a system of variable flow pumps controlled by a level sensor calibrated to the millimetre (along with a gravity-controlled overflow) to guarantee zero risk.

Sabine H., Process Engineer, Total Petrochemicals France.

Faced with the temporary operating constraint encountered on the site, the team from Aggreko offered us a solution which would meet our specifications working to a very strict timeframe. We appreciated the team's responsiveness and the strength of its proposal in respecting the setup and operational constraints.

We were able to fulfil our 'no waste' objective thanks to the mobile cooling solution which does not interfere with the operation of the networks.

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