EN
Introduction
As the coal chemical industry advances toward cleaner production, environmental compliance, energy efficiency, and sustainable resource use have become critical priorities. Flue gas desulfurization (FGD) technologies play a central role in reducing sulfur dioxide (SO₂) emissions, which are major contributors to acid rain and air pollution. Among the available options, ammonia-based FGD is increasingly recognized as the most effective solution for coal chemical plants. Its ability to integrate with existing ammonia sources, achieve high desulfurization efficiency, and generate valuable byproducts makes it an ideal choice.
The Need for FGD in Coal Chemical Plants
Coal chemical facilities produce a variety of byproducts, including ammonia, coke, and tar, during the conversion of coal into chemicals and fuels. The combustion of coal and byproduct gases generates sulfur-rich flue gas, which poses a serious environmental challenge. Traditional lime or limestone-based FGD systems often encounter operational limitations, such as scaling, waste disposal issues, and high maintenance costs. Ammonia-based desulfurization leverages in-plant ammonia sources, addressing both environmental and operational challenges efficiently.
Principles of Ammonia-Based FGD
Ammonia-based FGD uses ammonia (NH₃) as an absorbent to react with sulfur dioxide in flue gas. The reaction produces ammonium sulfite and ammonium bisulfite, which can subsequently be converted into ammonium sulfate fertilizer. This approach transforms harmful emissions into marketable byproducts, aligning environmental protection with economic benefit.
Chemical Reaction Overview:
SO₂ + 2NH₃ + H₂O → (NH₄)₂SO₃
(NH₄)₂SO₃ + ½O₂ → (NH₄)₂SO₄
The efficiency of ammonia-based FGD can reach 95–99%, depending on system design, ammonia dosing, and gas-liquid contact optimization. Modern designs also incorporate multi-stage spray absorption and aerosol control, minimizing ammonia slip and ensuring ultra-low emission levels.
Advantages in the Coal Chemical Industry
Integration with existing ammonia sources – Coal chemical plants often produce excess ammonia, which can be directly used for desulfurization, reducing external procurement costs.
High desulfurization efficiency – Modern ammonia-based systems maintain SO₂ emissions below 30 mg/Nm³, meeting the strictest regulatory standards.
Energy efficiency – The exothermic reaction releases heat, which can be partially recovered. Reduced liquid-to-gas ratios also lower pump and fan power consumption.
Multi-pollutant control – Advanced designs remove particulates (PM2.5), mercury, and other heavy metals simultaneously.
Byproduct utilization – Conversion of SO₂ to ammonium sulfate generates high-quality fertilizer, creating an additional revenue stream.
Case Example: Coal Chemical Plant in Fujian
A Fujian-based coal chemical plant implemented Shandong MirShine Environmental’s ammonia FGD system, achieving stable SO₂ removal efficiency above 99.2%, with ammonia slip averaging 1.2 mg/Nm³. The generated ammonium sulfate met GB 535-1995 fertilizer standards. The system also reduced energy consumption by ~20% compared to traditional limestone FGD, demonstrating both environmental and economic benefits.
Implementation Considerations
Flue gas characteristics: Low temperature (180–280°C) and high humidity favor ammonia absorption.
Ammonia dosing control: Precise metering prevents excess ammonia slip.
Integration with downstream NOₓ control: Optimized flue gas conditions enhance SCR/SNCR efficiency.
Maintenance and corrosion management: Material selection and system design ensure long-term reliability.
Conclusion
Ammonia-based FGD is the optimal solution for coal chemical plants aiming for ultra-low emissions, operational efficiency, and resource recovery. Its ability to integrate with existing production processes, convert pollutants into valuable fertilizers, and maintain stable performance under varying conditions makes it a strategic technology for sustainable industrial operations.