Vacuum System for Fiber Web Machines with Variable Speed Control
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Solution Overview
Problem
Existing vacuum systems in fiber web machines have low efficiency and poor adjustability, leading to significant energy loss due to the need for vacuum devices to be dimensioned for maximum requirements, which often exceed actual needs, and the use of vacuum release control, resulting in inefficient operation especially with the trend towards nip dewatering reducing capacity to a third or fourth of maximum capacity.
Innovation Solution
The vacuum system adapts to varying vacuum requirements by connecting vacuum devices to maintain constant pressure through a common manifold, varying motor rotation speed using frequency converters, and incorporating control devices and valves to adjust capacity without vacuum release air, allowing for high efficiency and flexible operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum devices are dimensioned according to maximum requirement, then the vacuum system can meet peak demand, but efficiency becomes low and energy loss increases when operating below maximum capacity
Solution Approach 1:
The patent applies dynamics by making the vacuum system adjustable through variable speed motors and frequency converters, allowing the vacuum capacity to dynamically adapt to actual process requirements rather than operating at fixed maximum capacity, thereby maintaining high efficiency across varying load conditions
Solution Approach 2:
The patent changes the operating parameters of vacuum devices by using frequency converters to vary motor speed and adjusting vacuum device capacity, enabling the system to operate efficiently at different vacuum levels and air volumes according to actual needs rather than fixed maximum settings
2Adaptability or versatility
If vacuum release control is used to reduce flow rate, then the vacuum device can operate at lower flow rates, but efficiency drops to below thirty percent causing significant energy loss
Solution Approach 1:
The patent replaces the mechanical vacuum release control system with an electrical control system using frequency converters and variable speed motors, eliminating the need for air injection and achieving flow rate adjustment without the energy losses associated with vacuum release control
Solution Approach 2:
The patent changes the operating parameters by using frequency converters to vary motor speed, allowing precise control of vacuum device capacity and flow rate without resorting to vacuum release control, thereby maintaining high efficiency across the full operating range
3Reliability
If each application requires its own vacuum device, then vacuum requirement is met for each location, but system complexity and energy consumption increase
Solution Approach 1:
The patent merges multiple vacuum device functions into a shared system with a common vacuum source that serves multiple applications through a manifold distribution system, reducing the total number of vacuum devices required while maintaining reliable vacuum supply to all locations
Solution Approach 2:
The patent creates a universal vacuum system where a single vacuum source with variable capacity can serve multiple different applications with varying vacuum requirements, achieving multi-functionality through adjustable capacity and individual zone control
4Ease of manufacture
If vacuum devices are placed in the basement, then space is optimized in the fiber web machine, but long negative pressure lines are required increasing system complexity
Solution Approach 1:
The patent segments the vacuum system into modular zones with a common vacuum source in the basement connected to multiple applications through a manifold system, allowing space optimization while managing line complexity through organized zonal distribution
Data Source
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AI summary
The invention relates to a vacuum system for a fiber web machine. The vacuum system includes several vacuum devices (10) each of which is provided with a motor (11, II1). In addition, the vacuum system includes negative pressure lines (12) for leading a vacuum from the vacuum devices (10) to the applications. The vacuum devices (10) are adapted to maintain constant pressure in the initial part of the negative pressure lines (12). In addition, the rotation speed of at least one motor (H') is adapted to be variable and the control devices (22) included in the motors (11, 11') are connected to each other for adjusting the capacity of the vacuum system. The invention also relates to a method in a vacuum system of a fiber web machine.