Abstract
Selective catalytic reduction (SCR) and denitrification are the best technologies for nitrogen oxides (NOx) control in coal-fired power plants, and their denitration efficiency and ammonia escape rate are closely related to their internal flow characteristics. By adding a deflector to the SCR device, the flow field in the curve can be effectively improved, and the stable and efficient operation of the SCR device can be realized. Based on the numerical simulation method, the SCR system of a coking coal-fired boiler in a steel plant was simulated using k-ε (the turbulence model), and three design schemes of deflectors were proposed and numerically simulated simultaneously. After optimization, the ammonia injection grid’s downstream velocity variance coefficient CV was 6.69, the catalyst upper cross-section velocity variance coefficient was 11.84, the cross-sectional temperature average was 499 K, the maximum temperature deviation was 9 °C, the maximum-to-minimum temperature interval span was 15 °C, the cross-sectional NH3/NOx molar ratio average value was 0.8122, the coefficient of variance was 4.67, and the pressure loss was 1855 Pa. The findings of this work will help improve the denitration efficiency and provide an important reference for the actual transformation design.
Highlights
Accepted: 14 February 2022With the rapid development of China’s modern industry and economy, energy consumption has increased rapidly [1,2]
The third 90◦ was arranged with four arc-shaped guide vanes, and a Thestraight-plate inlet-taperedsection section was with fourofstraight was set arranged at the outlet section the vane;guide plates; Five pieces of inclined straight guide vanes were arranged; The first 90° was arranged with three arc-shaped guide vanes, and the outThe rectifying grids were mm high, 100 mm apart, and had slopes on the left
Was 15%; (2) The upstream temperature field distribution of the first-layer catalyst: the maximum deviation of the flue gas temperature ratio from the average value was within the range of ±10◦ ; (3) The upstream of the first-layer catalyst velocity distribution: the maximum coefficient of variance (CV) in the cross section was 15%; (4) The upstream velocity angle of the firstlayer catalyst: the maximum angle deviated from the vertical line was ±10◦ ; and (5) The upstream ammonia distribution (NH3 /nitrogen oxides (NOx) ) of the first-layer catalyst: the maximum CV
Summary
With the rapid development of China’s modern industry and economy, energy consumption has increased rapidly [1,2]. Compared with most countries in the world, the reality of “rich coal, poor oil, and little gas” will determine that China’s coal-dominated energy structure will not undergo fundamental changes in the 30 to 50 years [4]. China’s coal consumption reached 4.49 billion tons in 2017, and it is estimated that by. 2023, China’s standard coal consumption will reach 4.7 billion tons [5]. In response to the above situation, since the “Twelfth Five-Year Plan”, the coal power industry has continuously strengthened the control of pollutant emissions; especially since 2014, ultra-low emission work has been rapidly promoted, and the level of the flue gas pollution control of coal-fired power plants in China has been significantly improved. The emission performance of the main air pollutants (smoke, SO2 , and NOx )
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