WUHAN UNIVERSITY OF TECHNOLOGY

Coal combustion mechanisms and fuel NO_x formation characteristics in a precalciner environment

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1 Double furnace reactor

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2 CO emission curves for bituminous coal combustion at different temperatures a) No. 1 bituminous coal b) No. 2 bituminous coal

3 CO2 emission curves for bituminous coal combustion at different temperatures a) No. 1 bituminous coal b) No. 2 bituminous coal

4 CO emission curves for anthracite combustion at different temperatures a) No. 1 anthracite b) No. 2 anthracite

5 CO2 emission curves for anthracite combustion at different temperatures a) No. 1 anthracite b) No. 2 anthracite

6 CO and CO2 yields for coal combustion at different temperatures a) CO yield b) CO2 yield

7 NOx emission curves for bituminous coal combustion at different temperatures a) No. 1 bituminous coal b) No. 2 bituminous coal

8 NOx emission curves for anthracite combustion at different temperatures a) No. 1 anthracite b) No. 2 anthracite

9 NOx yield and fuel N conversion to NOx for combustion of different coals at different temperatures a) NOx yield b) Fuel-N conversion

10 TG and DTG profiles for pyrolysis of coals a) No. 1 bituminous coal b) No.1 anthracite

11 FTIR spectrum for pyrolysis of No. 1 bituminous coal a) No. 1 bituminous coal b) No. 1 anthracite

As NO_x emissions become more and more severe it is important to find a method of low nitrogen combustion for coal in the precalciners in the cement industry. The operating temperature and the grade of coal have a great influence on NO_x formation. The rules governing NO_x formation during the combustion of two bituminous coals and two anthracite coals at 700-1000° C were therefore investigated in a double furnace reactor. The suggestions for controlling NO_x emissions in a precalciner are that, to ensure efficient decomposition of the raw material, a fuel with a high volatiles content and a high fixed carbon content should be chosen and the coal should be injected into the precalciner in a zone with a temperature not exceeding 900° C.

1 Introduction

Nitrogen oxides constitute one of the main air pollutants and the NO_x emission regulations for the cement industry are becoming more and more stringent. Precalciners are used in the cement industry as the main equipment for NO_x reduction. In the precalciner the fuel NO_x accounts for 80 % of the total NO_x from coal combustion, which is the main objective in the target for NO_x reduction [1-2]. Fuel NO_x is formed from the oxidation of the nitrogen combined in the fuel (600-800° C) when burning nitrogenous fuel [3-6]. To develop efficient NO_x reduction measures it is important to...

TEXT Junlin Xie^1,3, Xiaolin Chen^1,2, Shuxia Mei^1,2*, Hefeng^1,2, Yanghu^1,2, Liyang Zhong^1,2
¹State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan/China
²School of Materials Science and Engineering, Wuhan University of Technology, Wuhan/China
³Research and Test Centre of Materials, Wuhan University of Technology, Wuhan/China
*Corresponding Author: msx0303@163.com