Desulfurization and Denitrification Retrofit Plan for 100-ton Coal-fired Boilers

    I. Project Overview

    The heating system of the thermal power company consists of three 100-ton coal-fired boilers. The flue gas volume (per boiler, operating condition, 300°C) is 25,000 m3/h, with an exhaust gas temperature of 300°C. The concentration of NOx in the flue gas is 100 mg/Nm3. A combined denitrification process of in-furnace SNCR and external SCR is adopted.

     II. Structural Layout of the SNCR+SCR Denitrification System for Coal-fired Boilers

     This project uses urea as the reducing agent. The denitrification efficiency is not less than 50%, and the NOx content in the emitted flue gas is ≤ 50 mg/Nm³. The complete system mainly consists of a urea storage and supply system, urea solution delivery system, ammonia injection system, flue gas duct system, SCR reactor system, soot blowing system, compressed air system, and other components.

     Each boiler is equipped with a separate SCR system, while the urea storage and supply system, urea solution delivery system, and compressed air system are shared (reused) among the three boilers for denitrification.

    III. In this project, each boiler is equipped with a separate SCR reactor system, installed externally to the boiler. The SCR reactor is located outside the boiler, with the flue gas duct connected before the air preheater, passing through the SCR reactor and then reconnecting before the air preheater.The SCR reactor shell is an external structure containing catalyst supports, primarily composed of internally arranged catalysts, catalyst support beams, reactor shell, sealing plates, and other components.