Shengquan Group Thermal Power SDA Flue Gas Desulfurization Unit

The spray-drying desulfurization process is derived from the spray-drying production process for slurries. The spray-drying production process is widely used in modern industries that produce solid powders from liquid raw materials, such as the chemical, pharmaceutical, and food industries. The rotary spray drying desulfurization process offers advantages such as high desulfurization efficiency, a small footprint, and low capital and operating costs. Therefore, the rotary spray drying desulfurization process will undoubtedly become a competitive option in China’s power plant desulfurization market.

Basic Principles of the Spray Drying Absorption (SDA) Process

The basic components of a spray drying desulfurization system include: an absorbent slurry preparation system, a spray drying absorption tower, and a baghouse or electrostatic precipitator.

Untreated raw flue gas enters the spray-drying absorption tower through a gas distributor located at the top of the tower, where it comes into contact with fine lime slurry/absorbent droplets (average droplet diameter approximately 50 microns). The acidic components in the flue gas are rapidly neutralized by the fine alkaline droplets, while the moisture in the flue gas is simultaneously evaporated. Flue gas distribution, slurry flow rate, and droplet size are carefully controlled to ensure that the droplets are dried before they come into contact with the walls of the spray-drying absorption tower.

A portion of the dried products, including fly ash from the flue gas and the products of the absorption reaction, falls to the bottom of the absorption tower. The treated flue gas enters the subsequent dust collector (baghouse or electrostatic precipitator), where solid particles are collected. The clean flue gas treated by the dust collector is discharged through the chimney via an induced draft fan. Some spray-drying absorption processes incorporate a desulfurization ash recirculation loop, in which a portion of the recovered dry particles is pulped as an absorbent and returned to the atomizer to enter the absorption tower.

Although the material recirculation loop offers numerous advantages and can reduce lime consumption, the design of the loop may increase capital and maintenance costs and complicate the system due to variations in flue gas volume and SO₂ content. Therefore, the decision to adopt a desulfurization ash recirculation loop should be based on the flue gas composition and SO₂ emission concentration limits.

The 35-ton boiler in Phase I and the 75-ton boiler in Phase II of the Shengquan Group Cogeneration Project in Jinan, Shandong, both utilize our company’s SDA spray drying tower for desulfurization, achieving a desulfurization rate of over 90%.