A large UK refinery was experiencing an increase in the temperature of its hydrocarbon rundown on their Alkylation Unit. This was a result of under-performing dry coolers, which were being pushed to their maximum by an increase in production levels to meet a growth in
This increase in temperature had two knock-on effects. Firstly, the refinery had to flare-off the build-up of vapour to avoid over pressurising the tank, which was wasteful and not environmentally friendly.
Secondly, excess water vapour was passing through to the next stage of the refining process, which had the potential to corrode the vessels and damage the process.
Aggreko was challenged with finding a way to cool the hydrocarbon rundown stream so the customer could stop flaring and maximise production.
Following a number of detailed site visits, our process engineering team designed a solution that provided supplementary cooling capacity to support the existing plant.
We identified a suitable tie-in point to the customer’s rundown stream and connected our specialist shell and plate heat exchanger. On the other side of this heat-exchanger, we provided a cooling tower allowing a large quantity of heat to be rejected from a small footprint.
The solution provided 1.1 to 1.4 MW of additional cooling capacity (dependent on wet bulb temperature), reducing the temperature of the iC4 coolant and build-up of pressure and vapour in the butamer tank.
This was all done without the need to halt the plant’s production.
The equipment ran from July to September, to supplement the cooling capacity of the existing cooler until the ambient temperatures began to drop.
In the past, the site would have needed to limit their production during the summer months, due to the poor performance of their cooling plant.
Aggreko’s supplementary cooling package provided the additional cooling capacity that removed the safety and environmental concerns, so production could remain high to meet the market’s demands.