PDF《尿素制氨机理及影响因素分析》

第48 卷第2期热力发电Vol.

48 No.2

2019 年2月THERMAL POWER GENERATION Feb.

2019 收稿日期:2018-09-30 第一作者简介:王晓宁(1993―),硕士研究生,主要研究方向为电厂尿素制氨技术,wangxiaoning0128@126.com. 尿素制氨机理及影响因素分析 王晓宁,李文艳,王妮妮,白晨曦,肖海平 (华北电力大学能源动力与机械工程学院,北京 102206) [摘要]电厂采用的制氨方法有尿素热解法和水解法,针对某电厂

300 MW 机组利用 Aspen Plus 软 件对比分析了

2 种方案的优劣,从水解制氨系统的尿素进料质量分数、反应温度及压力

3 个方面,分析了不同反应条件对水解产物的影响.结果表明:水解方案反应温度低,可 采用低品质蒸汽作为热源且能耗量仅为热解的 20%~30%, 从节能角度出发, 水解制氨为最 佳方案;

随尿素进料质量分数的增加,产氨量增加,耗热量降低,但液相中尿素质量分数 也随之升高,易发生设备腐蚀;

随着温度的上升,尿素水解速率提高,但耗热量上升明显, 经济性较差;

增加压力能降低设备发生腐蚀的风险,但会对气体的析出产生抑制;

综合考 虑,尿素水解反应条件为尿素进料质量分数 50%,温度 150~160 ℃,压力 0.6~0.8 MPa 比 较合适. [关键词]烟气脱硝;

尿素;

热解;

水解;

Aspen Plus 软件;

反应条件 [中图分类号]X701 [文献标识码]A [DOI 编号]10.19666/j.rlfd.201809204 [引用本文格式]王晓宁, 李文艳, 王妮妮, 等. 尿素制氨机理及影响因素分析[J]. 热力发电, 2019, 48(2): 101-107. WANG Xiaoning, LI Wenyan, WANG Nini, et al. Mechanism and influence factors of ammonia production using urea[J]. Thermal Power Generation, 2019, 48(2): 101-107. Mechanism and influence factors of ammonia production using urea WANG Xiaoning, LI Wenyan, WANG Nini, Bai Chenxi, XIAO Haiping (School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China) Abstract: The ammonia production methods used in power plants include urea pyrolysis and hydrolysis. Numerical simulation was conducted by Aspen Plus for the two processes in a 300MW coal-fired power plant. From the aspects of urea feed mass fraction, reaction temperature and pressure, the effects of reaction condition on hydrolysis products were investigated. The results show that, compared with pyrolysis, the hydrolysis scheme has a lower reaction temperature, its energy consumption is only about 20%~30% of that of pyrolysis. What'

s more, low-quality steam can be used as the heat source of the hydrolysis scheme. From the point of energy saving, hydrolysis to ammonia is the best method. The simulation result shows a same tendency with the experimental data, verifying the reliability of the hydrolysis model. When the urea feed mass fraction was increased, the ammonia concentration in the product gas increased, the heat consumption decreased, while the urea in the liquid also increased, which leads to a rise in the risk of corrosion. As the temperature increased, the urea hydrolysis rate increased, but the heat consumption rose rapidly, and the economy was poor. Increasing the pressure can reduce the risk of corrosion. However, excessive operating pressure will inhibit the release of gaseous products. Considering comprehensively, the condition with urea feed mass fraction of 50%, temperature of

150 ° C~160° C and pressure of 0.6~0.8 MPa is suitable for the urea hydrolysis. Key words: flue gas denitration, urea, pyrolysis, hydrolysis, Aspen Plus software, reaction condition 近年来,我国大气污染物排放量不断增长,由 此引发的环境问题不容忽视.电厂排放烟气中所含 的NOx 是造成大气污染、光化学烟雾、酸雨的主要 根源之一.超净排放标准要求,在2020 年之前燃 煤锅炉 NOx 排放量必须降至