# Selection and Complete Configuration Scheme of Automatic Online Monitoring System Matched with Four Types of Anti-Corrosion Heating Tubes ## 1. Online Monitoring Supporting Scheme for 316L Stainless Steel Heating Tubes Core monitoring targets: wall thickness thinning caused by chloride corrosion, weld pitting corrosion, excessive temperature during alkaline cleaning, abnormal thermal resistance from scale accumulation, early warning of pipe wall rust shedding. Complete hardware configuration: online ultrasonic probes for wall thickness measurement, real-time medium chloride ion detection module, temperature interlock sensor for alkaline cleaning circuit, power and thermal resistance monitoring instrument, leakage collection alarm device at the bottom of the tank, upper computer data acquisition terminal. Linked control logic: Pop-up early warning automatically triggered when medium chloride ion concentration exceeds the standard; the heating circuit for cleaning is cut off immediately once alkaline cleaning temperature exceeds 60℃; equipment maintenance work order is pushed when wall thickness attenuation reaches 10%; continuous rise of heating power is judged as pipe wall scaling, and the CIP pickling procedure is automatically activated. Daily data management: Automatically record medium chloride ion content, peak alkaline cleaning temperature and wall thickness detection value of each batch, synchronize data into the full-life-cycle equipment file, and generate corrosion attenuation trend curves every quarter. Applicable control scenarios: Intermittent food fermentation, production lines with low-salinity neutral culture medium, which can avoid quality risks such as weld perforation and liquid leakage as well as heavy metal ion precipitation in advance. ## 2. Online Monitoring Supporting Scheme for Pure Titanium Heating Tubes Core monitoring targets: medium fluoride ion contamination, integrity of oxide passivation film, gas film accumulation on tube bundles, rust sediment deposition caused by galvanic corrosion of dissimilar metals, attenuation from large-area scratches on surfaces. Complete hardware configuration: online rapid fluoride ion detector for pipelines, electrochemical potential monitoring electrodes on pipe walls, exhaust flow sensor at the high point of tube bundles, wear detector for PTFE isolation sleeves on supporting flanges, dissolved oxygen detection module for circulating water. Linked control logic: Feeding is interlocked and stopped directly once trace fluoride ions are detected in feeding medium; oxygen-rich water circulation is automatically started to repair the passivation film when the surface potential of titanium tubes remains low; abnormal flow of exhaust valve is judged as bubble retention, and the flow rate of circulating pump is increased to flush the pipe wall; maintenance reminders for pipeline isolation accessories are pushed when rust falling from carbon steel supports is detected. Daily data management: Continuously record medium fluoride ion content, titanium tube surface potential change, dissolved oxygen content of cleaning water and exhaust flow data, form long-term passivation film stability curve, and set threshold alarm for fluoride pollution which is the most fatal risk of titanium tubes. Applicable control scenarios: 24-hour continuous sterile biopharmaceutical fermentation, high-chloride and weak alkaline culture medium without fluoride raw materials, realizing full-process closed-loop prevention of irreversible fluoride etching damage. ## 3. Online Monitoring Supporting Scheme for Quartz Anti-Corrosion Heating Tubes Core monitoring targets: microcrack expansion caused by thermal shock, permanent frosting and etching from alkali liquor misoperation, excessive power density operation, vibration impact damage of pipe bundles. Complete hardware configuration: real-time light transmission crack inspection sensor, alkali pipeline misoperation interlock switch, heating power density limiting controller, pipeline flow velocity monitoring transmitter, vibration frequency sensor at quartz fixing support. Linked control logic: The alkali liquid pipeline is automatically locked and a fault alarm is issued if the mechanical interlock fails to isolate alkaline cleaning fluid; power supply is cut off instantly when the actual power density exceeds 0.8 W/cm²; automatic flow reduction is triggered once the pipeline flow velocity is too high to reduce liquid scouring impact; maintenance inspection reminder is pushed when continuous abnormal vibration is detected. Daily data management: Archive light transmission inspection crack judgment records, alkali pipeline interlock test data, actual heating power operation records, and establish hidden danger tracking files for quartz tubes with slight microcracks. Applicable control scenarios: Laboratory small-volume intermittent reaction equipment, fluoride-containing acid working conditions without alkaline cleaning procedures, preventing fatal batch pollution accidents caused by quartz tube rupture and glass fragment shedding. ## 4. Online Monitoring Supporting Scheme for PFA Coated Heaters Core monitoring targets: long-term over-temperature aging of coating, penetrating scratches exposing carbon steel substrate, blistering and peeling of fluoroplastic layer, excessive oxidative degradation from high-concentration disinfectant. Complete hardware configuration: medium long-term temperature real-time monitoring sensor, coating surface visual scanning detection module, pipeline solid particle concentration detector, slow cooling program linkage controller, hydrogen peroxide concentration online detector. Linked control logic: Heating power is cut off for interlock protection when medium temperature exceeds 95℃ for a long time; equipment replacement reminder is automatically generated when penetrating scratches or blisters covering more than 5% of the coating area are scanned; the supply of high-concentration hydrogen peroxide is reduced once solid abrasive particle concentration in the medium exceeds the limit; the slow cooling procedure is forced to run after each high-temperature cleaning cycle to avoid rapid cold and hot alternation. Daily data management: Record real-time operating temperature curve of coating, coating damage area statistics, medium hard particle content data, track coating aging degree changes year by year, and arrange planned replacement in advance before complete coating failure. Applicable control scenarios: Low-temperature non-sterile chemical intermediate preparation tanks, mixed medium containing trace fluoride and weak alkali without GMP sterile production requirements, controlling the risk of plastic micro-particle shedding and internal substrate rust leakage. ## General Matching and Installation Specifications of Online Monitoring System 1. Independent monitoring partition layout: Install exclusive matched detection sensors in the production area of each heating tube material, and set independent alarm thresholds according to their core failure weaknesses to avoid unified parameter misjudgment. 2. Signal interlock isolation requirements: The monitoring circuit of titanium heating tube area must be isolated from fluoride feeding pipeline control signals; the monitoring system of quartz tube shall have hard interlock with all alkali liquid valves; the temperature sensor of PFA heater shall be equipped with independent power-off protection circuit. 3. Data audit traceability rule: All online monitoring data shall be stored for no less than 5 years, which can be directly exported as supporting audit documents for GMP, environmental protection and safety supervision inspection. 4. Regular calibration cycle: Calibrate chloride and fluoride ion detectors every month, calibrate wall thickness and potential electrodes every quarter, and conduct full-function joint debugging of the complete monitoring system every six months together with heating equipment preventive maintenance. ## Summary The configuration logic of the online monitoring system for four types of heating tubes centers on their respective fatal corrosion and failure risks. The monitoring system for stainless steel focuses on early warning of chloride pitting and alkali over-temperature; the titanium tube monitoring platform takes fluoride ion pollution and passivation film stability as core control points; quartz heating tube equipment is equipped with light transmission crack detection and alkali misoperation interlock as mandatory configurations; PFA coating monitoring mainly realizes whole-process temperature limitation and coating integrity scanning inspection. Equipping targeted automatic online monitoring systems can realize real-time early warning of potential equipment failures, eliminate unplanned shutdown losses and product quality pollution risks caused by heating tube aging and damage, and realize intelligent closed-loop full-life-cycle management of fermentation heating equipment.
