Project Description:

Zhenjiang MSW Plant New Project was invested by China Everbright International Limited in BOT mode. The concession period was 30 years. The aggregate investment amounted to 410 million yuan. The daily MSW treatment capacity of this project was 1000 tons.The project was equipped with three 350 t/d mechanical grate waste incineration furnaces and two sets of 12MW turbo-generators. The annual power generation capacity was 100 million kWh. Once put into operation, the project could meet the electricity demand of 30 thousand households. Nearly 42.1 thousand tons of coal equivalent was saved annually. The project sought a cut in CO2 emission of more than 120 thousand tons and a cut in COD emission of 4526 tons.

Based on the general contracting mode of EPC, our company undertook the dry process system of this flue gas purification system in this project in February 2011. The semi-dry reaction tower (rotary atomizer), activated carbon injection, bag filters were used in this project. On the basis of GB18485-2001, the emission indexes of the flue gas could meet EU 1992 standards, and the emission indexs of dioxins could meet EU 2000 standards. This dry acid removal engineering was designed to match three waste incineration furnaces. The new dry acid removal system was added between the original semi-dry reaction tower and the bag filter. Ca(OH)2 was sprayed into the system to further remove the HCL content in the flue gas, in order to guarantee that the HCl emission indexes could meet EU 2000standards. And the instant emission concentraiton of HCl was controlled to 5 mg/Nm3 or below.

Process Design:

In dry process system, slaked lime is sprayed into the inlet duct of the bag filter by pneumatic transmission and is fully mixed with the flue gas before entering the bag filter. Solid reaction bed was formed on the filter-bag, removing the acid gas in the flue gas (SOx, HCl, HF).　

The atomization spray system is installed on the top of the semi-dry reaction tower. When the semi-dry reaction tower breaks down or stops operation for repairing, the atomization spray system is used to reduce the flue gas temperature. In this case, the dry acid removal process could reach the optimum reaction temperature in order to meet the flue gas emission standards.