British Salt Completes Heat Exchanger Project

British Salt has recently completed one of a series of planned major projects at the Middlewich plant, replacing one of the heat exchangers used in the production of salt.

As part of its ongoing asset management plan to replace end of life equipment, the business has replaced one of the six heat exchangers used in the evaporation stage of the salt production process.  The completion of this project represents an investment of just under £1m in the plant’s future in order to maintain operating efficiency and reliability. 

The heat exchangers complete a critical role in the process, heating purified brine to evaporate water and generate, through six evaporation stages, an increasingly dense salt slurry.  The heat exchanger replaced in this project had been in operation for more than 30 years and was integrated into the existing plant. 

 

Unique Materials Selection

Working closely with heat transfer process specialist, Graham Hart Process Technology, British Salt has designed, installed and commissioned a new heat exchanger that incorporates exotic alloys such as Cupro Nickel to help mitigate the corrosive environment created when working with salt and brine.  Careful selection of these materials means that the 2280 brine tubes and the tube sheet that holds them in place have been specially constructed to be held securely without the need for welding.

 

Challenging Heavy Lift

Weighing 37 tonnes and nearly seven metres long by three metres in diameter, safely removing the old and installing the new heat exchangers represented a significant challenge.  The old unit needed to be vertically lifted from its position between two evaporation vessels, then rotated to a horizontal position before being lowered and loaded on to a flat bed HGV for removal from the plant. 

To ensure the integrity of the heat exchangers was maintained during lifting operations, British Salt conducted non-destructive testing on both units and Finite Element Analysis to ensure that the structures and lifting equipment were capable of withstanding the stresses placed on them. 

Working with lifting designer BritLift and mechanical contractor Peter J Douglass Engineering, British Salt used specially designed lifting lugs and a series of lifting beams and spreaders during the operation to lift, rotate and lower the heat exchangers using the plant gantry crane and a mobile crane.  Whilst it took eight months of planning, assessment and fabrication, the lifting part of the removal and installation only took a matter of minutes to complete.

 

Successful Commissioning & Operation

Completed during the plant’s annual maintenance shutdown, the new heat exchanger has now been successfully commissioned.

 

The project in numbers:

  • 12 months planning
  • 8 months design & build
  • 6 weeks of site preparation
  • 37 tonnes to be lifted, twice
  • 2280 tubes through which brine is heated
  • 1 days removing old HE
  • 1 days installing new HE
  • 30 minutes to lift the old HE out and
  • 30 minutes to lift the new HE into place
  • 5 minutes to transfer the HE’s from their vertical to horizontal position and vice versa
  • 8m diameter, 6.7m in length