新型三床变温吸附空气净化流程的性能研究

Air separation is an energy intensive process that consists of three main steps: air pre-purification, air separation, and product gas compression. Specifically, the air pre-purification process is obviously energy inefficient, due to there is a considerable waste heat in the discharged gas of the commonly used temperature swing adsorption air pre-purification unit (TSA-APU). Since this waste heat is characterized by low temperature and intermittent, it is difficult to be effectively utilized by conventional techniques. From the standpoint to use the waste heat within the TSA-APU itself, we have proposed a three-bed process to substitute the two-bed process which was employed in the existing TSA-APU. The three-bed process allows the TSA-APU to work at high energy efficiency because it can achieve waste heat recovery by recovering, reheating and reusing the discharged gas as its purge gas. The energy saving principle of the three-bed process is evident, but the purification performance of the three-bed process is hard to be figured out without performing particular study. This is because that the resulting hot purge gas for the three-bed process is essentially the discharged gas, which contains some water and is different from the water-free purge gas for the two-bed process. In order to understand its energy saving degree, its purification performance, and the effects of recovered gas on the purification performance, the three-bed process will be intensively studied in this project by both theoretical and experimental methods.

空气分离系统是耗能大户，其能耗主要来自三部分：空气净化，空气分离和产品气压送。其中，空气净化过程能源浪费明显，因为目前常用的变温吸附空气净化装置（TSA-APU）排放的再生尾气中含大量余热。该余热存在温度低、间歇排放的特点，采用常规技术难以有效回收利用。对此，本项目以TSA-APU余热自利用为切入点，提出采用三床切换流程替代目前TSA-APU所采用的双床切换流程。三床流程通过将再生尾气回收、补热后作为再生气重新用于吸附床加热以实现余热回收，从而显著改善TSA-APU能源利用效率。三床流程的节能原理简单明显，但它的净化性能则需通过具体研究才能明确。这是因为三床流程采用再生尾气作为再生气，而再生尾气中含有水蒸气,这一点明显不同于双床流程所使用的无水再生气。为了明确三床流程的节能效果和净化性能，掌握回收再生尾气对净化性能的影响规律，本项目计划对其进行深入的理论研究和实验研究。

本项目提出一种用于空气纯化的三床TSA流程。三床流程通过将再生尾气回收、补热后作为再生气重新用于吸附床加热以实现余热回收，从而显著改善能源利用效率。三床流程的节能原理简单明显，但它的净化性能则需通过具体研究才能明确。这是因为三床流程采用再生尾气作为再生气，而再生尾气中含有水蒸气，这一点明显不同于双床流程所使用的无水再生气。本项目基于TSA过程数学模型及其数值模拟，理论上证明了三床TSA流程可实现显著节能，且其产品空气质量符合工业标准。同时，本项目对三床TSA流程进行了实验研究，实验验证了三床TSA流程的产品空气质量符合工业标准。研究结论表明：新型三床TSA流程可实现空分装置TSA预纯化系统节能30%以上，对于完成钢铁生产节能降耗任务具有积极的现实作用。