Maintenance and Technical Development of TQ-T Straight-Type Extraction Tank

The TQ-T straight-type extraction tank is a multi-functional process equipment widely used in the extraction of active plant ingredients, aromatic oil collection, solvent recovery and other production processes. The complete equipment consists of a straight cylinder body, jacket heating unit, defoamer, condenser, cooler, oil-water separator, filter assembly, circulating pipeline and pneumatic slag discharge mechanism. The material contact parts are made of 304/316L stainless steel, equipped with CIP online cleaning devices and pressure & temperature monitoring components. It supports multiple process modes including water decoction, thermal reflux and forced circulation dynamic extraction, complying with the production specifications of pharmaceutical, food and fine chemical industries. The long-term operational stability, process reproducibility and service life of the equipment rely on a standardized hierarchical maintenance system. Meanwhile, with the upgrading of manufacturing technology, digital control and green production requirements, such equipment is continuously iterated and optimized.

I. Equipment Maintenance and Management

Equipment maintenance is divided into three levels: daily inspection and maintenance, periodic in-depth maintenance, and long-term shutdown preservation. In accordance with the characteristics of pressure vessels, calibration of safety accessories is implemented to ensure production compliance and operational reliability.

1. Daily Inspection and Maintenance (Per Shift)

Daily maintenance focuses on pre-production and post-production inspection, on-site cleaning and operational status confirmation, serving as the basic measure to prevent sudden failures. Before startup, check the supply status of water, steam and compressed air to ensure the air pressure is within the designed range of the equipment. Verify the smooth operation of the slag discharge door locking cylinder and hinged pin shaft, the effectiveness of the interlock safety mechanism, and no hard material residue on the sealing surface. Confirm that safety accessories including pressure gauges, temperature transmitters and safety valves are within the valid calibration period, the sight glass and explosion-proof lamp are intact, and all connecting flanges are free of leakage. Heating and pressure boosting operations are strictly prohibited when the slag discharge door is not fully locked.

After production, activate the built-in CIP rotating spray ball to clean the inner tank wall, feeding port and pipeline dead angles to remove herbal residues and colloidal deposits. Disassemble and clean the tank bottom filter sieve plate and filter screen to clear blocked materials in filter holes via compressed air back-blowing. Hot water circulating flushing is required for high-viscosity materials to prevent dry coking and subsequent liquid discharge blockage. Dredge the defoamer, condenser tube bundle, cooler and oil-water separator, and drain residual media inside the separator to avoid scaling and internal corrosion caused by static retention. Check the sealing condition of all valves and ensure no air leakage of pneumatic components. Wipe the equipment surface, organize pipelines, and fully record key parameters such as working pressure, temperature and operation duration to complete the equipment operation log.

2. Periodic In-depth Maintenance (Monthly, Quarterly and Annual)

Monthly Maintenance: Conduct a comprehensive inspection of all sealing parts, focusing on the main sealing ring of the slag discharge door and pipeline flange O-rings to check for hardening, scratches, swelling and deformation. Seals are prone to aging and damage under organic solvent working conditions. For local leakage, adjust the locking mechanism first and replace failed parts directly; it is forbidden to cover sealing defects by increasing compression force. Fill suitable lubricant for friction parts such as cylinder hinge points and pin shafts. Check the vibration and mechanical seal leakage of the circulating pump. Clean impurities inside the steam trap to prevent blockage, which may cause jacket water accumulation, reduced heat exchange efficiency and even water hammer risks. Remove residual sediments from pipeline dead angles and inspect welding joints for corrosion points.

Quarterly Maintenance: Drain condensed water accumulated at the bottom of the jacket and inspect the jacket layer for rust and bulging. Recheck the torque of all pipeline fasteners and calibrate the zero point of temperature and pressure display instruments. Disassemble and clean the duplex filter to check the integrity of the filter element. Verify the rotational flexibility of the CIP spray ball to ensure full cleaning coverage without blind spots. For corrosive material production conditions, focus on inspecting the polished inner tank wall for pitting corrosion and record all corrosion conditions in detail.

Annual Maintenance: As a pressure vessel, the equipment requires systematic maintenance and safety verification every year. Conduct non-destructive testing on the tank jacket, welds and connecting pipes. Send pressure gauges and safety valves to qualified institutions for mandatory calibration. Fully disassemble and inspect the slag discharge door opening and closing mechanism, cylinders and bearings, and replace parts with excessive wear. Perform complete functional tests on the electrical control system, grounding protection and interlock logic. Remove scale from condenser heat exchange tubes, as excessive scale will directly reduce condensation and recovery efficiency and increase solvent loss. Sort out equipment maintenance and parts replacement records completely to meet GMP data integrity filing requirements.

3. Long-term Shutdown Preservation Maintenance

For planned long-term equipment shutdown, complete the full cleaning process to empty all materials from the tank, pipelines, condenser and separator, and dry thoroughly with hot air to avoid inner wall corrosion caused by residual liquid and moisture. Do not keep the seals of the slag discharge door and feeding door tightly locked for a long time; loosen the locks appropriately to prevent permanent deformation and failure of gaskets under long-term compression. Apply anti-rust protective agent on movable metal hinge parts, implement dust and moisture prevention for the electrical control cabinet, and cut off external water, power and steam supplies. Conduct regular inspections during shutdown to avoid potential hidden damage in the preserved state.

4. Management of Key Wear Parts

Rubber seals, PTFE sealing components, filter screens and plates, cylinder piston sealing rings and circulating pump mechanical seals are high-frequency wear parts, for which a spare parts account shall be established. Organic solvents and acidic extraction conditions will accelerate seal aging, and modified perfluoroether sealing materials can be adopted to extend the replacement cycle. Filters with cracks or perforations must be replaced immediately to prevent solid herbal residues from entering subsequent pipelines and condensers, causing pipeline blockage and auxiliary equipment damage.

II. Future Technical Development Direction of TQ-T Straight-type Extraction Tank

Against the background of intelligent, continuous, green and low-carbon upgrading of the pharmaceutical and plant extraction industries, the TQ-T straight-type extraction tank is no longer limited to single-tank extraction functions, and is iteratively developing towards material upgrading, intelligent closed-loop control, process integration, green energy saving, predictive maintenance and flexible modularization.

1. Structural and Corrosion-resistant Material Upgrading

Traditional 316L stainless steel can meet most water and alcohol extraction working conditions. For highly acidic, high-salt and strongly corrosive extraction media, duplex stainless steel and composite material lining solutions will be gradually promoted to improve the tank's resistance to pitting and intergranular corrosion and extend equipment service life. The surface of movable parts is strengthened by tungsten carbide spraying to reduce the wear rate of pin shafts and locking mechanisms. Ordinary rubber seals are gradually phased out and replaced with solvent-resistant modified PTFE and perfluoroether rubber to reduce seal replacement frequency and downtime maintenance costs. The internal flow channel design of the tank is further optimized to reduce cleaning blind spots, improve solid-liquid flow conditions, alleviate local scaling and material adhesion, and reduce CIP cleaning consumption.

2. In-depth Application of Intelligent and Process Analytical Technology

At present, most TQ-T extraction tanks complete batch production through manually set temperature and time, with the extraction end point judged empirically, resulting in inconsistent process quality among batches. In the future, multi-dimensional sensor arrays will be widely deployed to collect tank temperature field, pressure and solvent vapor flow data. Combined with online spectral detection equipment, it can monitor the concentration of active ingredients in liquid medicine in real time and realize automatic judgment of extraction end points, eliminating traditional empirical operation modes. A virtual equipment model is built based on digital twin technology to map actual operational data, simulate internal temperature distribution and mass transfer processes inside the tank, provide early warning of abnormal working conditions, realize adaptive adjustment of process parameters, and reduce quality differences between different production batches. Electronic batch records automatically collect and store all production data to meet the mandatory regulatory requirements for data integrity.

3. Predictive Maintenance Replacing Traditional Scheduled Maintenance

Current equipment maintenance mostly adopts scheduled inspection and maintenance mode, causing unnecessary replacement of unworn parts and failure to identify potential hidden faults in advance. In the future, the equipment will be equipped with vibration, temperature and current monitoring sensors to collect real-time status data of key components such as circulating pumps, cylinders, bearings and seals. An equipment health assessment model will be established to realize advance fault prediction. The maintenance mode will shift from breakdown maintenance and scheduled maintenance to predictive maintenance, which can reasonably arrange maintenance time windows, reduce unplanned shutdowns, avoid unnecessary consumption of spare parts, and improve the overall equipment operation rate.

4. Green Energy Conservation and Efficient Solvent Recovery

Energy conservation and emission reduction have become core indicators for equipment upgrading. The original jacket heating, condensation and cooling systems of TQ-T equipment operate independently with insufficient energy utilization. The new generation of equipment will promote waste heat recovery and reuse of secondary steam. It optimizes the heat exchange structure of condensation and cooling systems to reduce cooling water consumption, and builds a closed-loop solvent recovery control system to dynamically adjust cooling medium flow, improve organic solvent recovery rate, reduce solvent volatile emission, and lower material loss and environmental treatment pressure. Meanwhile, the tank thermal insulation structure is optimized to reduce surface heat dissipation loss, cut down steam consumption per unit product, and meet the construction standards of green factories.

5. Modular Integration and Adaptation to Continuous Production

Traditional TQ-T straight-type extraction tanks mainly adopt single-batch intermittent production mode. In the future, modular design will be widely adopted, with standardized integration of the tank body unit, defoaming, condensation, oil-water separation and filtration units. Multiple tank groups can share utility systems, simplify workshop pipeline layout, shorten product changeover and commissioning time, and adapt to flexible production of multi-variety and small-batch products. To meet the demand of continuous extraction processes, the feeding, slag discharge and liquid outlet structures will be adaptively modified to connect with pre-treatment and solid-liquid separation units, gradually realizing continuous feeding of raw materials, automatic discharge of herbal residues and continuous output of extraction liquid, breaking the capacity limit of intermittent production and improving the automation level of the whole production line.

6. Standardized Control System Adapted to Industrial Internet

The equipment control system is evolving from standalone single-machine control to workshop-level industrial interconnection. As the core unit of the extraction workshop, the TQ-T extraction tank can connect equipment data to the factory MES platform, realizing automatic production instruction issuance, centralized parameter monitoring and automatic maintenance work order generation. It bridges the data link between the equipment layer and production management layer to support smart factory construction. In addition, the software and hardware design complies with international industry specifications to improve the versatility and compatibility of the equipment.

III. Conclusion

The comprehensive performance of TQ-T straight-type extraction tanks depends on both the original manufacturing quality of the equipment and the complete and implemented hierarchical maintenance system. Standardized daily inspection, periodic overhaul and wearing parts management can effectively avoid common faults such as leakage, blockage and reduced heat exchange efficiency, ensuring stable process operation and safe production. Facing industrial upgrading, such equipment will continue to evolve in the directions of new corrosion-resistant materials, intelligent process control, predictive operation and maintenance, energy-saving recovery and modular continuous production adaptation, providing solid hardware support for high-quality production in the plant extraction industry.