化学吸收法碳捕集技术是燃煤电厂脱碳的重要途径，但高能耗制约了其发展。集成MVR热泵的工艺流程改进作为降低捕集能耗的重要手段，现有研究大多以软件模拟优化该流程，存在约束条件选取不灵活、参数优化仅对MVR环节局部优化和模拟流程繁琐等缺点。为弥补以上研究不足，以300 MW机组及年产量200万t碳捕集系统数据为基础，对集成MVR热泵的解吸单元进行约束条件设置灵活、优化过程直观的整体建模优化。首先建立MEA吸收CO2热力学模型及MVR热泵设备数学模型，得到MVR热泵工艺流程设计参数。在此基础上，以最小等量解吸能耗为目标函数，对贫富液换热器小端差及二次蒸汽压缩终压进行优选。之后基于优选结果，在二次蒸汽压缩终压为140 kPa，贫富液换热器小端差为5 ℃时，对MVR系统闪蒸压力进行优化。优化结果表明，最优闪蒸压力为109.2 kPa，捕集系统最小等量解吸能耗为2.82 GJ/t（以CO2计），相比于常规碳捕集系统节能率(5.61%)节能效果明显。对集成MVR热泵的节能优化方案的经济性分析结果表明，节能方案总投资为708.28万元，年净收益523.55万元，收益净现值为3 449.2万元，投资动态回收期为1.5 a。

Chemical absorption method is an important way to capture carbon dioxide in coal-fired power plants,but the high energy consumption in the process restricts its development.The carbon capture process integrated MVR pump is an important means to reduce energy consumption. The main drawbacks of current researches,which mainly use software for simulation optimization,are inflexible selection of constraint conditions,the local optimization of parameters for the MVR part and complicated simulation process. In order to address the lack of researches,based on the data of the carbon capture system that captures 2 million tons of carbon dioxide annually,the overall modeling optimization of the desorption unit integrated with MVR pump was carried out with flexible constraint selection and simple and intuitive optimization process. Firstly,the thermodynamic model of CO2 absorption by MEA and the mathematical model of MVR heat pump equipment were established,and the design parameters of the MVR heat pump process flow were obtained. On this basis,taking the minimum desorption energy consumption as the objective function,the small terminal difference and the final pressure of secondary steam compression of the lean and rich liquid heat exchanger were optimized. Then,based on the optimization results,the flash pressure of MVR system was optimized when the final pressure of secondary steam compression was 140 kPa and the small end difference of lean and rich liquid heat exchanger was 5 ℃. The optimization results show that the optimal flash pressure is 109.2 kPa,and the minimum equivalent desorption energy consumption of the capture system is 2.82 GJ/t (in terms of CO2). Compared with the conventional carbon capture system,the energy saving is 5.61%,with obvious energy saving effect. The economic analysis results show that the investment of energy saving optimization scheme of integrating MVR pump is 7.082 8 million yuan,the annual net income is 5.235 5 million yuan,the net present value is 34.492 million yuan,and the dynamic payback period of the investment is 1.5 years.

0 引言

1 碳捕集系统集成MVR热泵工艺流程

   1.1 常规碳捕集系统

   1.2 MVR热泵节能原理

2 碳捕集系统集成MVR热泵设计优化

   2.1 单乙醇胺吸收CO2的热力学模型

   2.2 MVR系统主要单元设备数学模型的建立

   2.3 热力参数优化

3 优化结果

   3.1 二次蒸汽压缩终压优选

   3.2 贫富液换热器小端差优选

   3.3 基于最优参变量的闪蒸压力优化

4 经济性分析

5 结论