Minimising the Impact of Effluent Treatment

Innovative solution delivers ROI in just 2 years

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A large brewer targeted a reduction in steam demand for their Anaerobic Digestion Effluent Plant. The site was using 10% of its steam to meet the preheating demands of the plant, which led to natural gas costs totalling £215,000 per annum. The primary goal reduce gas use and emissions by developing a solution to satisfy the effluent plant heating demand using alternative heat sources.

Key project stats

  • Plant – 4.5M hL / annum
  • Savings –  £880k / annum

What we did

Several different technology options were reviewed based on fit of solution and financial viability:

  • Regenerative heat recovery from Effluent Plant outflow
  • Heat recovery from new refrigeration plant cooling tower water or heat pump
  • Heat recovery from a pasteuriser cooling tower
  • Heat recovery from a steam boiler condensing economiser
  • Addition of  a biogas CHP to the Effluent Plant

The above were all analysed whilst taking into account:

  • Feasibility
  • Risk
  • Cost (CAPEX or financed)
  • Payback (ROI)
  • Lifetime Profitability (NPV)

How we did it

We completed in depth data analysis of the effluent plant heating demand vs potential heat sources. The half hourly profile of heat demands is often poorly understood leading to heat being dumped when demand is low or being in short supply during demand spikes. One of the key challenges was the effect on seasonal temperature variations affecting the capability and requirements of the plant.

The technology options outlined were specified and modelled to analyse their performance. This included variations of each type of technology including:

  • Heat exchanger suitability: Spiral, Corrugated Tubular and Wide Gap Plate
  • Biogas CHP modelling with various heat recovery options
  • Gas Boiler condensing economiser heat recovery system
  • Fridge plant heat pump vs straight recovery from existing heat rejection loop

With extensive knowledge on energy systems applied within the brewing industry, we were able to successfully design several costed solutions to the problem. Our service included:

  • Identifying viable solutions through initial modelling
  • Carrying out site audits with plant operators and equipment suppliers
  • Specifying and costing the optimal solution and calculating financial metrics such as ROI and NPV.

Outcome

The project demonstrated the phased implementation of a condensing economiser, and a Biogas CHP provided the best solution to offset the heating requirements of the effluent plant, and maximise return on investment. Providing an ROI of 2.1 years and a NPV in excess of £3M over a ten year period.

Reducing site carbon emissions is key for us to meet our environmental targets. Carbon Architecture’s work has allowed us to make the best decision on how to tackle our Effluent Heating Requirements. We look forward to working with them on implementation.
Site Engineering Manager

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