I. Overview
Supercritical drying technology is a new chemical technology developed in recent years. Because of the surface tension of the solvent in the gel skeleton, the skeleton will collapse under ordinary drying conditions. Supercritical drying aims to make the solvent reach its critical point during the drying process by controlling the pressure and temperature, and complete the transition from liquid phase to supercritical fluid. In the process, the solvent has no obvious surface tension, and the transformation from wet gel to aerogel is completed on the premise of maintaining the skeleton structure.
Second, the main technical parameters
Gel dryer: 1L/32MPa, 300℃
Separator: 0.6L/20MPa, 85℃
Refrigeration system: 2400kcal/h, air-cooled, core imported components.
Tank: 2L/16MPa
High pressure delivery pump: 5L/40MPa
Frequency converter: 1.5kW
Third, the main structure composition
The supercritical aerogel drying device is mainly composed of: air source system, refrigeration system, voltage stabilizing system, temperature control system, pressure control system, drying device, separation device, electrical control, support box and so on.
Iv. Description of structural breakdown
4-1, air supply system:
Generally, CO2 is used as the drying medium, and the system is provided by the user. If it is not supplied by domestic gas cylinders or directly by non-gas cylinders, the specification and size of the gas source access port shall be provided for the normal operation of the device access system.
4-2, refrigeration system:
This system consists of refrigeration unit, cold box, freezing coil, cold circulating pump, etc. It is a gas source liquefaction system, which provides liquid gas source in the critical replacement process of supercritical drying.
Refrigeration unit:
Refrigeration form: air-cooled, and the core components are imported from France to ensure the stable supply of refrigeration needs of the device.
Cold box: stainless steel 304, the inside is treated by special technology to ensure no leakage.
Refrigeration coil and cold circulating pump:
The exchange design of Cu elbow and stainless steel elbow 304 is adopted to increase the refrigeration area and enhance the refrigeration effect. Equipped with 300W cold circulating pump to increase the refrigeration and heat exchange convection in the cold box.
4-3, high pressure pump:
High-pressure plunger CO2 pump is selected as power transmission to ensure the stable supply of drying medium, and the pump head is made of special materials, which can adjust the demand of fluid volume in each stage of the test in time.
Pressure range: normal pressure ~ ~20MPa
Flow: 16L/h
Frequency converter: 1.5kW
4-4, flow metering system:
The CO2 gas in the pipeline is measured by gas mass flowmeter combined with flow digital display instrument, and the measurement accuracy reaches 1% F.S..
Flow control range: 0 ~ 10l/h
4-5, temperature control system:
PID program is used to control the temperature, and the temperature is adjusted according to the temperature increase range, such as 0.5℃/min, 2℃/min, etc. Setting the temperature gradient adjustment value, the system carries out self-tuning automatic control, and the whole process is completed automatically without manual operation.
Temperature control range: normal temperature ~ 300℃
4-6, pressure control system:
Precision back pressure regulating valve for control. Inlet pressure: ≤40MPa
Outlet pressure: 0 ~ 20 MPa
Applicable medium: weakly corrosive
4-7, drying device:
The volume is 1000ml, the internal precision grinding treatment, the design pressure is 32MPa, the temperature is 300℃, the internal size is φ Φ100×120mm, the internal temperature is measured, and the external thermal insulation device is designed.
4-8, separation device:
The separation device is the main place for gas-liquid separation, where most of the liquid is effectively recovered, and the recovered liquid can be recycled again after collection, and the gas enters the next link through the upper outlet.
Separation volume: 600ml
Separation pressure: 20MPa
4-9. Preheater:
Used for preheating drying kettle, preheating temperature: ≤250℃.
4-10, condenser:
Used for cooling the front end of the pressure control system to ensure the normal operation of the pressure control system.
4-11, electrical control and box bracket:
According to the requirements of modern laboratory, the shape design of the equipment is beautiful and generous. Adopt aluminum-plastic profile frame, stainless steel molding control panel, man-machine operation environment, proper layout, and harmonious with modern laboratory.