Parallel Pump Feeding System for Continuous Digester
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Solution Overview
Problem
Modern continuous digester systems face challenges with high operational costs, limited accessibility, and inefficiencies in pumping wood chips due to the need for multiple pumps in series, which are costly and prone to shutdowns if one pump fails, and struggle to maintain optimal flow rates and chip concentration across varying production capacities.
Innovation Solution
A feed system utilizing multiple pumps in parallel, arranged at ground level for easy maintenance, with a combination of transfer lines to maintain high pressure and flow rates, allowing for efficient operation across a broader production capacity range without the need for high-pressure pocket feeders or multiple pumps in series, ensuring optimal chip transfer and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple pumps in series are used to feed wood chips to the digester, then the chips can be transported to high elevation, but the system becomes complex, costly, and prone to shutdowns if one pump fails
Solution Approach 1:
The patent divides the pump system into multiple independent pumps operating in parallel rather than a single complex series system. Each pump handles a portion of the total flow requirement, allowing independent operation and maintenance without shutting down the entire system.
Solution Approach 2:
The patent incorporates redundancy by having multiple pumps available to compensate for potential failures. If one pump fails, others can continue operating to maintain the required chip feed rate, cushioning against production interruptions.
2Stress or pressure
If high-pressure pocket feeders are used to maintain pressure during chip transfer, then pressure is preserved, but the feeder is subjected to wear and requires frequent adjustment to minimize leakage
Solution Approach 1:
The patent replaces the mechanical high-pressure pocket feeder system with a pump-based system that uses mechanical energy from the pumps to directly pressurize and transport the chip slurry. This substitution eliminates the wear-prone pocket feeder components while maintaining the required pressure levels.
3Productivity
If multiple pumps in series are used to handle varying production capacities, then flow rates can be adjusted, but the system requires many different pump sizes and high operational costs
Solution Approach 1:
The patent employs multiple pumps of the same or similar models operating in parallel, where each pump is designed to handle a standard portion of the total capacity. By combining multiple identical units, the system achieves variable production capacity without requiring a wide variety of different pump sizes, simplifying maintenance and reducing costs.
4Productivity
If pumps are installed at elevated positions to feed the digester, then chip transfer is efficient, but accessibility for maintenance becomes difficult
Solution Approach 1:
The patent resolves the accessibility problem by positioning the parallel pumps at ground level or accessible locations, using the parallel configuration and pipeline network to achieve the required elevation and pressure for efficient chip transfer to the digester.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces operational costs, improves accessibility, and maintains consistent chip concentration across varying production levels, enabling efficient operation with fewer pump sizes and simplified maintenance, while ensuring reliable chip transfer to the digester.
Implementation Method 1
maintain a high pressure in the transfer circulation to and from the digester
Implementation Method 2
the flow of chips does not need to pass through pumps, but is instead transferred hydraulically
Implementation Method 3
the chips are pumped from an impregnation vessel to a digester in which the chips are cooked in a steam atmosphere. Here, a part of the cooking liquor is charged to the pump to obtain a pumpable consistency of 10%
Data Source
AI summary
The feed system is for a continuous digester where at least two pumps are arranged in parallel at the bottom of a pre-treatment vessel. The outlets of the pumps are combined at a merging point before a common transfer line extends to the top of the digester. The system makes it possible to provide a feed system with an improved accessibility and operational reliability, and to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.