Lock Hopper Feeding Layout for Low-Density Biomass Under Pressure
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Solution Overview
Problem
Existing lock hopper designs are inadequate for handling high volumes of low-bulk-density and pressure-sensitive feedstocks, such as biomass materials, as they lead to operational issues like packing and arching, and there is a lack of practical configurations for arranging multiple lock hoppers to reliably feed pressurized environments.
Innovation Solution
A system comprising a surge bin, converging-diverging hoppers, screw feeders, and tangentially injected gas nozzles is used to minimize packing and arching, allowing for continuous and reliable feeding of bulk materials into pressurized environments using an array of lock hoppers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional lock hoppers with converging sections are used to feed bulk materials, then the outlet can be made smaller than the hopper geometry, but this causes packing and arching issues with low-bulk-density and pressure-sensitive feedstocks
Solution Approach 1:
The patent inverts the conventional converging hopper design by using diverging sections instead. The hopper has a large inlet that diverges downward to a smaller outlet, which is the opposite of the conventional approach. This inversion prevents material from becoming trapped and packed in the hopper, eliminating arching issues while maintaining reliable material flow to the pressurized environment.
Solution Approach 2:
The patent changes the geometric parameters of the hopper from converging to diverging sections. Specifically, the hopper includes a first diverging section with walls that diverge from the inlet toward the outlet, and a second diverging section that continues this pattern. This parameter change in the hopper geometry fundamentally alters material flow characteristics, preventing packing and arching of low-bulk-density feedstocks.
2Productivity
If multiple lock hoppers are used to increase volumetric feed rate, then high-volume feeding can be achieved, but the physical arrangement and filling of many lock hoppers becomes complex and difficult to implement
Solution Approach 1:
The patent segments the feeding system into multiple lock hoppers (at least three, preferably four or more) that operate in parallel. Each lock hopper is an independent unit with its own diverging hopper and screw feeder, allowing the system to handle high volumetric feed rates while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent combines multiple lock hoppers into a single integrated system that feeds one pressurized environment. The lock hoppers are arranged around the pressurized vessel, with their outlets converging toward the feed point. This merging of multiple independent units creates a coordinated system that achieves high productivity without excessive complexity.
3Quantity of substance
If conventional lock hoppers are used with low-bulk-density feedstocks like biomass, then the system cannot handle the required large volumes, but increasing the hopper size increases packing and pressurization sensitivity
Solution Approach 1:
The patent inverts the conventional hopper geometry to diverging sections, which prevents material from being compressed and packed as it flows downward. This inversion allows the system to handle large volumes of low-bulk-density feedstocks like biomass without increasing pressurization sensitivity, because the material flows freely under gravity through the expanding cross-section.
Solution Approach 2:
The patent uses diverging hopper sections that expand in cross-sectional area as material flows downward, adding a dimensional aspect to the flow path. This dimensional change allows large volumes of material to be accommodated without increasing pressure, as the material distributes itself across a larger area throughout the hopper.
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
The system enables efficient and reliable feeding of large volumes of low-bulk-density feedstocks by minimizing consolidation and arching, ensuring continuous operation and flexibility in pressurization cycles.
Implementation Method 1
at least three gas injection nozzles arranged to be equidistant from each other and configured to inject or withdraw gas into the lock hopper in a tangential manner
Implementation Method 2
inject or withdraw gas into the lock hopper in a tangential manner
Implementation Method 3
one or more screw feeders. Each screw feeder disposed at an outlet of each converging-diverging hopper and configured to move material from the hopper into an inlet valve of a lock hopper
Implementation Method 4
surge bin for receiving bulk material
Implementation Method 5
one or more converging-diverging hoppers in fluid communication with the surge bin
Data Source
AI summary
A system and method for feeding a high volume of low-bulk-density and pressure-sensitive feedstocks into a pressurized environment. The system includes a lock hopper filling system, one or more lock hoppers, a feed bin, and a feeder. The methods involve using such a system to feed bulk materials into a pressurized environment by feeding bulk material from a low pressure into the surge bin, filling the one or more lock hoppers from the surge bin, operating the lock hoppers, and discharging lock hoppers into feed bin, and discharging feed bin into the high-pressure zone using feeder.