Ammonia Desulfurization Offers CHP Plants an Alternative to Seasonal Gypsum Disposal Costs

As the heating season approaches, combined heat and power (CHP) plants face a familiar challenge: maintaining reliable heat supply while managing the large quantities of desulfurization gypsum generated by continuously operating flue gas desulfurization (FGD) systems.

For some plants, gypsum disposal has become a significant operating expense. Recent project figures show considerable regional differences. During the 2025–2026 heating season, Weihai Thermal Power Group's gypsum removal project recorded a price of -RMB 30 per tonne, meaning the plant had to pay for removal. Other projects in China recorded disposal prices ranging from approximately RMB 56 to RMB 155 per tonne.

Carbon-related costs are adding further pressure. As companies pay greater attention to carbon emissions and solid-waste management, the economics of traditional limestone-gypsum desulfurization are receiving renewed scrutiny.

Ammonia-based flue gas desulfurization offers a different approach. Instead of producing gypsum as the main by-product, the process uses ammonia to absorb sulfur dioxide (SO₂) and produces ammonium sulfate, a material used in fertilizer production.

The timing may offer an additional advantage. The end of the heating season generally coincides with China's spring fertilizer preparation period, creating opportunities to connect industrial by-product recovery with agricultural demand.

Several industrial enterprises have already applied this approach. Yangzi Petrochemical's thermal power division uses ammonia desulfurization to convert boiler flue gas SO₂ into ammonium sulfate, while Zhong'an United had supplied more than 3,000 tonnes of ammonium sulfate by March 2026.

MirShine Group provides calcium-to-ammonia conversion solutions for existing limestone-based FGD systems. Its technology reports an SO₂ removal efficiency above 99.5% and an ammonia recovery rate of at least 99%. Where site conditions permit, existing desulfurization towers and plant buildings can be reused to help control retrofit investment.

For CHP plants, ammonia desulfurization presents an alternative way to manage sulfur emissions while recovering a potentially valuable by-product. Rather than treating gypsum disposal as an unavoidable seasonal expense, operators can evaluate whether sulfur resource recovery offers a more suitable long-term approach to flue gas treatment.