Paper Machine Vacuum System
Paper machine vacuum system can effectively influence paper machine efficiency, paper sheet dehydration and press felt performance, so what’s the factor will affect paper machine vacuum sysetem efficiency?
Paper Machine Vacuum System Efficiency
1. The sealing water becomes hot: The increase of the sealing water temperature (above 32.2~37.7℃) will reduce the efficiency of vacuum pump and reduce vacuum system efficiency. The ability of vacuum system on a high vacuum device (such as couch roll) can reduce up to 25%. This means that the vacuum degree reduction of couch roll affects the dehydration ability, or requires additional energy to achieve the required vacuum degree.
2. Irregular or higher sealing water pressure caused large sealing flow: When the sealing flow is too large, the energy demand increases 2%-5% or more, this is mainly depending on the pump model and operating conditions. In addition, excess water must be conveyed into the vacuum system by pump and pumped out of the vacuum system, which consumes more energy. The large amount of seal water flow is usually due to pressure instability or lack of seal water holes.
3. System design or operation problems cause vacuum pump back pressure: Vacuum pump will appear back pressure in some old systems, if not air, water discharge system for improvement, back pressure will be expanded. Theoretically, a vacuum system should not have more than 6.9kpa backpressure (in the case of pump outflow) in vacuum drainage. Fiber or scale in the drainage pipe accumulation will cause backpressure, in the drainage system, the water level in the ditch will also cause back pressure, and is not conducive to the separation of ditch and moisture.
