Abstract: This paper introduces a radar level gauge—the Siemens Sitrans LR400—employing four-wire, 24GHz, continuous frequency modulation (FMCW) technology. It successfully solved the level measurement problem in the fatty alcohol polyoxyethylene ether storage tank at the Fushun Petrochemical Detergent Plant. Keywords: Radar level gauge, fatty alcohol polyoxyethylene ether, continuous frequency modulation (FMCW), four-wire system. Background: The Fushun Petrochemical Company's Synthetic Detergent Plant is a modern enterprise reorganized by China National Petroleum Corporation (CNPC) through the acquisition of the former Fushun Alcohol Ether Chemical Plant and the assets of the former Fushun Chemical Plant. It is a surfactant production base designated by CNPC and a key pillar industry for development during the "Eleventh Five-Year Plan" period. The plant is the largest synthetic detergent raw material production enterprise in Asia and the most technologically advanced in China. Its main products are fatty alcohol polyoxyethylene ethers (aeo2-aeo9) and nonylphenol polyoxyethylene ethers, among others. These products are widely used in detergents, pesticides, cosmetics, textiles, coatings, papermaking, leather, plastics, food, mining, and petroleum industries, and are key raw materials for high-efficiency biodegradable detergents and widely used industrial auxiliaries. With the expansion of the plant's scale, how to effectively achieve fully automated control and reduce unit production costs has become a problem faced by the Fushun Petrochemical Detergent Plant. Among these challenges, the level measurement data of the finished product storage silos for fatty alcohol polyoxyethylene ethers is crucial for the plant's overall asset management and control. Unfortunately, a reliable automated level measurement solution has yet to be found. At a technical seminar organized by Siemens, we learned that Siemens' Sitrans LR400 radar level meter could effectively measure the level of plastic powders such as PVC and PE powders, which greatly interested us. Afterwards, we consulted with Siemens' instrumentation engineers and felt that the LR400 might be able to solve our level measurement problem. Siemens also provided a lot of support, arranging for relevant technical experts to analyze our operating conditions and provide on-site installation guidance. Fatty alcohol polyoxyethylene ether is a major component of laundry detergent, and its basic properties are similar to those of laundry detergent. The main measurement difficulties are: 1. Very low dielectric constant. After consulting relevant materials, we learned that laundry detergent has a very low dielectric constant: approximately 1.4 to 1.5. Because media with low dielectric constants are easily penetrated by radar waves (electromagnetic waves), the echo signal is too weak to be measured. Therefore, many radar level gauges provided by manufacturers are essentially unusable. 2. Prone to clumping, large angle of repose. Fatty alcohol polyoxyethylene ether materials are relatively sticky and particularly prone to clumping. Furthermore, the large angle of repose of the material pile will cause strong scattering effects in many non-contact measurement methods, resulting in poor measurement results. 3. High dust levels. Fatty alcohol polyoxyethylene ether powder is fed using pneumatic conveying, resulting in very high dust levels in the silo, causing significant interference and very low visibility. According to the sales engineer from Siemens Instruments, we learned about some technical features of the Sitrans LR400: 1. Its unique design principle enables it to measure media with dielectric constants as low as 1.5; 2. The four-wire design ensures maximum energy transmission from the radar level gauge; 3. The continuous frequency modulation (FMCW) microwave measurement principle greatly improves the instrument's measurement reliability; 4. A beam angle as small as 8° (generally, the higher the microwave transmission frequency, the smaller the beam angle can be), effectively avoiding various interferences from inside and around the tank; 5. The unique horn antenna and dust cover design effectively prevents material agglomeration; 6. Patented intelligent acoustic echo processing technology, based on field application experience of over 700,000 level gauges worldwide, is the world's earliest and most powerful level measurement echo processing technology; 7. The user-friendly yet powerful LabVIEW and PDM debugging software provides powerful functions such as parameter setting, echo recording, fault diagnosis, and handling of various types of echo interference; 8. An intrinsically safe, explosion-proof infrared handheld device was provided as a debugging tool, making the debugging process safe, fast, and simple. After communication and understanding, we were very confident in our solution for measuring the level of fatty alcohol polyoxyethylene ether silos using the LR400. Since this was our first time using the product, Siemens sent engineers to design and implement the on-site installation location and method, including the length of the installation riser. Through simple training, we were also able to master the parameter setting method for remotely debugging the LR400 using an infrared handheld device. In February 2006, the Sitrans LR400 arrived on-site. After simple installation and debugging, the instrument was working normally. During more than six months of use, the LR400 performed very stably and reliably. We also had instrument technicians conduct on-site measurements with a measuring tape for comparison, and found that the LR400's measurement values ​​were quite accurate. [align=center]Figure: Application of Sitrans LR400 in a fatty alcohol polyoxyethylene ether silo[/align] The use of the LR400 has effectively solved our plant's level measurement problem, reducing the workload of on-site workers. We also believe that this non-contact measurement method can meet the maintenance-free requirement, and the gauge is designed for a 10-year lifespan. Therefore, the plant is very satisfied with the successful use of this gauge. References: 1. Siemens (China) Co., Ltd. Sitrans LR400 Radar Level Gauge Operation Manual. 2005.2 2. Yang Cheng, Ge Guangyu. Successful Application of Siemens Radar Level Gauge in Shanghai SECCO Polystyrene Plant. Petrochemical Automation. 2006.1 3. Bo Guangyin, Application of Level Measurement Technology in Lafarge Cement. Cement Technology, 2006,2