Parallel Pump Feed System for Continuous Digester
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Solution Overview
Problem
Conventional feed systems for continuous digesters face challenges such as high operational costs, limited accessibility, and inefficiency due to the need for multiple pumps in series, which are costly and prone to shutdowns, especially in large-scale operations exceeding 4000 tons pulp per day, where maintaining optimal flow and chip concentration is difficult.
Innovation Solution
A feed system utilizing multiple pumps in parallel, arranged at ground level, with a pre-treatment vessel that maintains high static pressure to prevent cavitation, allowing for efficient transfer of wood chips to the digester, and incorporating a combination of transfer lines to ensure constant flow and chip concentration, enabling operation across a broader production capacity range with fewer pump sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple pumps in series are used to feed chips to the digester, then the chips can be transported to the top of the digester, but the system complexity increases and accessibility deteriorates
Solution Approach 1:
The patent transitions from a vertical arrangement (pumps in series at height) to a horizontal arrangement (pumps in parallel at ground level). This dimensional change allows multiple pumps to operate simultaneously at ground level, reducing system complexity while maintaining transport capability to the digester top.
Solution Approach 2:
The patent divides the chip transport function into multiple independent parallel pump units instead of a single series chain. Each pump handles a portion of the total flow, and they can be independently maintained or replaced, improving accessibility and reducing overall system complexity.
2Stress or pressure
If high-pressure pocket feeders are used for pressurisation and transport, then pressure can be maintained in the circulation, but wear increases and adjustments are required to minimize leakage
Solution Approach 1:
The patent replaces the mechanical high-pressure pocket feeder system with a pump-based system. The pumps generate and maintain pressure electronically/control-driven, eliminating the mechanical wear and leakage issues inherent in pocket feeder designs while maintaining the required pressure in the circulation system.
3Speed
If pumps in series are used, then chip transport is achieved, but operational costs increase due to limited accessibility and shutdown risks
Solution Approach 1:
By segmenting the transport function into multiple independent parallel pumps at ground level, the system allows individual pump maintenance without shutting down the entire system. This improves ease of operation and reduces operational costs by maintaining continuous chip transport capability.
Solution Approach 2:
The patent introduces a parallel pump configuration as an intermediary system that mediates between the need for continuous operation and the need for maintenance. The redundant parallel arrangement ensures that if one pump is serviced, others continue to transport chips, eliminating operational interruptions.
4Adaptability or versatility
If multiple pump sizes are used to cover production capacity range, then adaptability improves, but installation and maintenance costs increase
Solution Approach 1:
The patent employs multiple identical parallel pumps that can each handle a portion of the total production capacity. This universal configuration allows the system to adapt to different production levels by operating different numbers of identical pumps, rather than requiring different sized pumps, thereby reducing installation and maintenance costs.
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 optimal chip concentration across varying production levels, enabling efficient and reliable operation with fewer pump sizes, thus lowering installation and maintenance costs.
Implementation Method 1
a pre-treatment vessel that maintains high static pressure to prevent cavitation
Implementation Method 2
pumping of the chips mixture from a low pressure to a high pressure level
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
The invention relates to a feed system for a continuous digester (6) where at least 2 pumps (12a, 12b) are arranged in parallel in the bottom of a pre- treatment vessel (3) and a stirrer (1) is provided in direct connection to the inlets to the pumps. The invention makes it possible to provide a feed system with an improved accessibility and operational reliability, and with the possibility to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.