After entering the 1980s, the development of industrial production technology is very rapid, and the society has imposed higher demands on environmental protection, coupled with the fierce international market competition, requiring industrial production to ensure that products have stable high quality, but also to minimize costs. Therefore, online analysis technology is increasingly widely used in all aspects of industrial production, whether it is distributed control system (DCS), advanced process control (APC), or real-time optimization system (RTO), fast and reliable online analysis technology is very critical (Fig. 4.1). The timely and accurate analysis data provided by it plays a vital role in stabilizing production, optimizing operation, and saving energy and reducing consumption [1–3].