Case study: Solvay soda ash plant in Spain
Industrial plant and SOLVAir® - Key figures
1.1 kg of sodium bicarbonate (SOLVAir® SB 0/3) consumed per ton of steam produced
Dust in exhaust: under 5 mg/Nm3, dry, 6% O2
SO2 in exhaust: 190 mg/Nm3, dry, 6% O2
The customer’s - Solvay - needs: mitigation to reach compliance
Cleaning up dust and SO2
Solvay’s soda ash manufacturing plant in Torrelavega, Northern Spain, needed to treat the flue gases from its coal-fired steam boilers in order to comply with the legislation. Due to the nature of the fuel, the aim of the flue gas treatment was to mitigate SOx and dust.
What SOLVAir® did: installation of a full flue gas treatment system
Initially equipped with electrostatic precipitators to remove the dust from their flue gases, the boilers were retrofitted in 2018 with a desulfurization treatment consisting on a bag filter and a sorbent dosing system that injects precisely measured amounts of sodium bicarbonate (SOLVAir® SB 0/3), which is produced onsite by the plant, into the boiler exhaust.
Optimized amounts of sorbent
Two silos (one for sorbent and one for the residues), three grinders and two bag filters with extraction fans were installed to complete the system. Patented SOLVAir® nozzles are used for the Dry Sorbent Injection (DSI) to get optimal mixing, enabling flue gas treatment with very low sorbent excess (close to stoichiometry).
Easily operating below the legal limits
The result is that for both dust and SO2, the plant’s exhaust successfully reached values that are below legal thresholds: 5 mg/Nm3 for dust, when the legislation calls for no more than 10 mg/Nm3, and 190 mg/Nm3 for SO2, with a legal maximum at 200 mg/Nm3.
Recent trials have shown the possibility to go below 50mg/Nm3 with an optimum sorbent consumption with the existing equipment.
Benefits for the customer, Solvay: compliance coupled with efficiency
The main benefit of installing SOLVAir®’s flue gas treatment system was for the soda ash plant to become fully compliant with regulations. But an additional advantage was lowering the facility’s operating costs, thanks to the system’s high energy efficiency and low sorbent excess, which enables the reduction of logistics costs.
"The DeSOx installation, which is based on the dry injection of sodium bicarbonate produced on site, started up quickly and smoothly on both coal-fired boilers. The performance of the DeSOx installation is in line with our expectations for the project."