Enhanced Waste-to-Energy boiler efficiency by adding Sorbacal® Heat

Zabalgarbi S.A., a Waste-to-Energy plant in Bilbao (Spain), has one furnace (30 t/hr) and processes approximately 220 kt/yr of  household and non-hazardous industrial waste.

The site is equipped with a semi-dry treatment consisting of a milk of lime injection prepared with Sorbacal^® Q (calcium oxide) upstream of a bag filter operating at a temperature of around 150°C.

Zabalgarbi aims to prepare the plant for greater flexibility in processing various non-recyclable waste streams. However, these 
alternative fuels may alter the composition of fly ash, potentially reducing boiler performance and increasing the frequency and cost of cleaning and maintenance.

Zabalgarbi and Lhoist started collaborating in 2023 with the aim of finding a global and sustainable solution for the plant. 

To respond to Zabalgarbi’s continuous improvement objectives, our Lhoist experts recommended the injection of Sorbacal^® Heat. This product range has been developed by Lhoist to enable in-furnace capture of SOx (> 850ºC) and to tackle slagging (molten or partially fused ash deposits on radiative heat exchanger walls) and fouling issues (deposits on convective heat exchanger surfaces), caused by the low melting temperature of fly ash.

To evaluate the performance of the reagent, Zabalgarbi tested Sorbacal^® Heat 3425 for fifteen months. 

• Our engineers designed a tailor-made reagent by creating a dry and fine powder with the perfect combination of Calcium and Magnesium to comply with Zabalgarbi’s needs. Additionally, we performed Computational Fluid Dynamics to optimize location of injection points in the furnace and provide the needed technology to ensure correct dispersion and reliable dosing throughout the testing period. 
• Zabalgarbi and Lhoist partnered together for the trial follow-up (sampling analysis and operational data control every 2 weeks: boiler temperature/pressure, waste throughput, steam and residue generation etc..) and made the necessary adjustments in Sorbacal^® Heat injection and semi-dry system automation.

Over the fifteen-month trial period, it was demonstrated that the injection of Sorbacal^® Heat had a very positive impact in Zabalgarbi’s installation. 

• Acid gas removal: effective deSOx pre-treatment in furnace, leading to effective SO₂ peak control, semi-dry scrubber debottlenecking and overall lower SOx emissions at stack 
• Boiler efficiency: > 7% increase in thermal power generation, > 5% increase in waste throughput, savings on maintenance costs & safety improvements. Combined with existing automated online cleaning, manual cleaning was almost eliminated thanks to the more brittle and easier-to-clean fly ash.

By collaborating closely with our customers, we ensure the solutions we deliver are as efficient as possible. We tailor our solutions to maximize efficiency and deliver measurable value