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This post was last edited by sdwfsgyykai on 2019-10-2 at 08:00. Summary: Regarding the float level gauge installed at the inlet of the tank used to store the hydrating catalyst for cyclohexanol production, the corrosion of the catalyst liquid caused the steel strip to break, resulting in the float falling and making it impossible to accurately monitor and control the level of the hydrating catalyst. An advanced domestic radar level monitoring system was adopted; this system enables accurate measurement of the liquid level in the tank without any need to come into contact with the liquid surface. This approach avoided the need for complicated shutdowns for maintenance, as well as losses and leaks of the catalyst material caused by overfilling, achieving excellent results in terms of technical improvement. The cyclohexanol production unit at Pingdingshan Shenma Wanli Chemical Co., Ltd. was introduced from the Japanese company Asahi Kasei. During operation, defects in both the process and the equipment related to the hydration catalyst storage tanks became apparent; these defects not only affected the production capacity and efficiency of the entire cyclohexanol production unit but also led to catalyst leakage and environmental pollution. To address this situation and break through foreign technological restrictions, a technical upgrade was carried out on the float level gauge systems used in those catalyst storage tanks. This upgrade enabled a complete process of localization, involving introduction, digestion, absorption, and further innovation, and the performance of the catalyst storage tank level monitoring system has reached advanced levels comparable to those in the international industry. 1 Existing problems: In the cyclohexanol hydration catalyst reaction system, the A-D308 hydration catalyst storage tank is a visually accessible level gauge tank designed specifically for storing the hydration catalyst, enabling online monitoring of its liquid level. The installed steel-band float level gauge suffered damage due to prolonged exposure to the corrosive nature of the hydrated catalyst solution; this led to the breaking of the steel band in the gauge, causing the float to fall off. There are no standard procedures for carrying out maintenance tasks on such gauges, so it is not possible to repair them while the plant is still in operation. To prevent leaks of catalyst material caused by high liquid levels and to ensure production safety, it is necessary to shut down the entire plant for maintenance. Moreover, repairing the steel-band level gauge requires cleaning the tank before maintenance personnel can enter it to replace the damaged components, which results in significant losses of hydrated catalyst and **increases the difficulty and cost of equipment maintenance.** 2 Technical Principle of Radar Level Gauges Radar level gauges are top-down online travel measurement systems used to determine the distance from a reference point (the top of the tank) to the surface of the liquid medium. The measurement of a radar level gauge is accomplished by the antenna emitting microwaves, which are reflected at the surface of the liquid medium being measured and then received by the radar antenna. After being converted by electronic circuits, the signals are sent to a microprocessor for processing. Its features include easy installation, no moving components, low maintenance requirements, high precision, and strong reliability. Its ultra-high sensitivity along with unique signal processing capabilities enable it to function well in complex industrial environments. The transmitter probe and radar antenna are interchangeable, which meets production needs and helps to prevent overfilling of tanks. This also facilitates equipment maintenance and extends its service life. 3. Technical improvement plan: While ensuring safe and normal production, the use of radar level gauges enables accurate measurement of the liquid level in the tanks. It is possible to replace vulnerable components without having to empty and clean the tanks, thereby overcoming problems such as catalyst leakage and loss that occur during shutdowns for maintenance. This approach ensures long-term operation of the entire cyclohexanol production facility. The schematic diagrams of the level gauge before and after modification are shown in Figure 1 and Figure 2. http://www.tuan22.com/scimage/8eb7559142fc552b577fc60ee6f39df6.jpg http://www.tuan22.com/scimage/1c4e130620a22b04ec63f8d250885c28.jpg A circular manhole with a diameter of 100 mm was installed on tank D308 for the installation of an instrument radar level gauge (4” ANSI 150RF). The on-site display unit of the level gauge is placed next to tank D308 at a height of 1.5 m above the ground, to facilitate inspections by operators; the level signal is sent to the DCS control room via wiring. 4. Implementation effects: The radar level gauge is primarily composed of electronic components and an antenna, featuring an integrated design without any movable or mechanical parts. As a result, it experiences few failures during operation, has a long service life, and is easy to maintain. It overcomes the shortcomings associated with steel-band float level gauges in terms of process and equipment performance. Its funnel-shaped design enables non-contact measurement; the electromagnetic waves emitted by the radar do not require any transmission medium, and they are not affected by physical factors such as the density, concentration, pressure, or temperature of the liquid in the tank. Additionally, the radar level gauge has a large measurement range, up to 35 meters, and it can be integrated with both on-site display systems and DCS control systems for remote signal transmission, making it suitable for the special operating conditions in chemical manufacturing plants. 5 Economic benefits: The imported steel-band float level gauges cost 300,000 yuan per unit, while domestic radar level gauge systems cost 1 million yuan per unit. Steel-band float level gauges need to be replaced annually. The modified cyclohexanol hydration catalyst A-D308 storage tank has been in continuous operation for two years without any leakage issues, saving the enterprise 1.7 million yuan in equipment acquisition costs. The parking for maintenance takes 2 days each time. With a cyclohexanol production of 170 t/year and a cost of 0.8 ten thousand yuan per ton, the annual economic loss amounts to 2.72 million yuan. It saves costs such as maintenance expenses, catalyst loss costs, and utility consumption costs, by approximately 200,000 yuan. By upgrading the steel-band float level gauge systems used in the hydrated catalyst storage tanks with domestically produced alternatives, Pingdingshan Shenma Wanli Chemical Co., Ltd. improved the technical equipment level of its facility; as a result, the comprehensive performance of its catalyst storage tank level monitoring system surpassed that of imported equipment, setting a leading example in the cyclohexanol production industry. Authors: Wang Liushuan, Wang Maijian, Zhuang Xinseng