Application Instructions of Vacuum Pumps Matched with Drying Equipment

When vacuum pumps are equipped for drying equipment, the core purpose is to create a negative pressure vacuum environment, lower the temperature required for vaporization of moisture inside materials, realize low-temperature drying, and prevent heat-sensitive materials from deterioration under high temperature.

Under vacuum drying working conditions, the vacuum pump continuously extracts air and water vapor inside the drying chamber to maintain stable negative pressure within the cavity. The lower the air pressure, the lower the boiling point of water. Moisture in materials can evaporate at temperatures far below 100°C. It is especially suitable for dehydration treatment of high-temperature intolerant materials such as chemical raw materials, extracts, food raw materials and pharmaceutical intermediates.

Different types of drying equipment shall be matched with different vacuum pumps. Water ring vacuum pumps are widely adopted for vacuum ovens and batch vacuum dryers. Featuring simple structure, they can withstand inhalation of a small amount of water vapor with low failure rate and maintenance cost. For continuous drying equipment requiring higher vacuum degree and generating less water vapor, rotary vane vacuum pumps can be adopted. Condensing devices are generally installed to condense and recover water vapor in advance and reduce corrosion caused by direct inflow of water vapor into the pump body.

During operation, massive water vapor directly entering the pump chamber tends to cause medium emulsification and rusting of internal parts. Therefore, condensers and gas-water separators are usually installed between drying equipment and vacuum pumps in the whole system to separate most water vapor, reduce the load on vacuum pumps and extend their service life.

Vacuum drying systems demand stable vacuum degree. The selection of vacuum pumps shall be comprehensively determined according to the volume of drying chamber, single batch material handling capacity, target dehydration rate and operating temperature. If the pumping speed is too low, negative pressure will build up slowly and the drying cycle will be prolonged. Excessive pumping capacity will increase energy consumption and may carry away part of light materials.

With the advantages of moisture resistance and high reliability, water ring vacuum pumps are the most commonly supporting model for medium and small vacuum drying production lines, applicable to drying production lines with large water vapor output and ordinary working conditions. For anti-corrosion requirements, stainless steel pump bodies are optional to extract acidic and corrosive volatile gas.

Water Ring Vacuum Pump (Most mainstream for vacuum drying)

Application: Batch vacuum drying ovens, vacuum rake dryers, vacuum rotary drying equipment, drying systems with large inflow of water vapor

Rotary Vane Vacuum Pump

Application: Vacuum drying systems with less water vapor volatilized from materials, equipped with pre-condensers and requiring higher vacuum degree

Roots Vacuum Pump + Water Ring Vacuum Pump Unit (Roots-Water Ring Vacuum Unit)

Application: Large continuous drying equipment, production lines requiring high pumping speed, medium-high vacuum degree and high dehydration efficiency

Screw Vacuum Pump

Application: High-end closed drying, working conditions with abundant organic solvent volatilization and requirements against oil contamination