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Trinseo Benelux BV
13 Jan 2016

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Cefic announced on 08/10/2015 the winners of its European Responsible Care Awards, during a special ceremony at its annual general assembly in Brussels. Under the auspices of this competition Trinseo Benelux (NL) received a special commendation for its project “Energy Efficiency through steam re-compression”. The company was praised for the creative way to use steam previously blown off to the atmosphere or condensed against cooling water at its site in Terneuzen (NL).

Trinseo Benelux BV is part of Trinseo S.A. (formerly known as Styron). It is a global company producing emulsion polymers (Latex and Rubber) and plastics (polystyrene, copolymers, polycarbonate, compounds and blends). The company also operates two Styrene Monomer units to provide its downstream business with raw materials. The yearly revenue is around $5.3 billlion, employing approx. 2,100 people in 27 countries.

Terneuzen Industry Park
Trinseo is part of this industry park (also known as Dow Chemical Benelux BV), which supplies heat in the form of steam to the plants at 3 levels (35, 12 and 3.5 bar). The steam is consumed at the level required by the single operation units, but always at the first higher level available. The steam is generated in a Combined Heat and Power (CHP) plant and at various process units connected to the site's grid. Before the energy efficiency measures were implemented an excess of the lowest steam level (3.5 bar) was created (for 7 of the 12 months of the year) as there were no alternatives to use this steam.

The solution
In 2012 a team of process and production engineers in the Styrene Monomer (SM) technology centre came together to brainstorm on ideas on how to further improve the energy efficiency in the process. The initial idea was to lower the boiling point of the hydrocarbon raw material/water mix fed to the SM unit by adding more water and thus getting closer to the azeotropic point (that is to say the point where the proportions of the liquids in the mixture cannot be altered by simple distillation). The aim was to try to get the boiling point so low that it could be evaporated with 3.5 bar steam. This was not possible because of the pressure needed at the receiving unit.

At this point, and considered the aforementioned results, another idea was proposed: to use 12 bar steam (until then used to evaporate the mixture) to drive a steam jet sucking in 3.5 bar steam and in this way raising its pressure to 5 bar, which is the pressure needed at the receiving unit. Doing so, a total of 240 -300 tonnes per day of low steam replaced the 12 bar steam. The effect was that the blow-off to the atmosphere of 3.5 bar steam is reduced in the same amount, which means that it doesn't need to be generated anymore thus reducing energy consumption and related CO2 emissions.

The steam re-compression solution applied at Trinseo's site has improved both energy and extraction efficiencies. The company believes that this novel technique can have applications in other integrated sites struggling to make their site energy grids more efficient. It can create as well opportunities in sites not producing excess heat by raising the need for low-pressure steam and unlocking heat-recovery projects to date blocked in production units. It is worth noting that the investment payback time for the above described solution is 2 to 3 years and it does not require external infrastructure.

Below a timeline of the project, from its conception until is successful implementation:

  • Mar – Jun 2012: Discussions about energy reduction possibilities and first ideas on azeotropic evaporation using 3.5 bar steam
  • June – Dec 2012: Further project definition introducing the idea to use steam jet to provide the appropriate steam pressure (5 bar) to evaporate the azeotropic mixture.
  • Jan 2013: Kick-off & front end loading of the project
  • Feb 2013: Cost estimate for project implementation
  • Jun 2013: Project authorised (€640,000)
  • Jul 2013 – Mar 2014: Implementation phase
  • April 2014 – present: Successful operation of the unit

*Steam savings match design expectations --> 2 – 3 years payback time of the investment 

 

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