Powder Supply Device Pressure Compensation for Accurate Weight Measurement
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Solution Overview
Problem
Existing powder supply devices face challenges in accurately controlling the flow rate of pulverized fuel due to inaccuracies in weight measurement caused by pressure changes in the expansion/contraction part, leading to incorrect adjustments of the powder discharge valve and differential pressure, which affects the accuracy of powder flow control.
Innovation Solution
A powder supply device and method that includes a load cell to detect the weight of the feed tank, with a controller subtracting the force exerted by the expansion/contraction part's internal pressure to accurately calculate the powder weight and rate of change, and uses valves to control the flow rate by maintaining a set pressure in the expansion/contraction part, ensuring accurate flow rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion/contraction part is used to accommodate pressure changes in the feed tank, then the feed tank can maintain pressure equilibrium, but the internal pressure of the expansion/contraction part causes it to expand and push the feed tank downward, resulting in incorrect weight detection by the load cell
Solution Approach 1:
The system is divided into two separate measurement functions: the load cell measures the total weight (feed tank + powder + expansion force), while the pressure sensor measures the internal pressure of the expansion/contraction part. These segmented measurements are then combined through subtraction to obtain the accurate powder weight, resolving the contradiction between maintaining pressure equilibrium and ensuring measurement accuracy.
Solution Approach 2:
The pressure sensor acts as an intermediary element that measures the expansion force generated by the expansion/contraction part. This intermediary measurement allows the system to compensate for the erroneous weight detection by subtracting the pressure-derived force from the load cell reading, thereby eliminating the measurement error caused by pressure changes.
2Productivity
If the aperture of the powder discharge valve and differential pressure are adjusted based on load cell readings, then the powder flow rate can be controlled, but inaccurate weight detection leads to incorrect adjustments and reduced control accuracy
Solution Approach 1:
The system implements a feedback mechanism where the controller continuously receives data from both the load cell and pressure sensor, calculates the corrected powder weight in real-time, and uses this accurate information to adjust the powder discharge valve aperture and differential pressure. This feedback loop ensures that flow rate control decisions are based on accurate measurements, resolving the contradiction between productivity and control accuracy.
Solution Approach 2:
The controller performs preliminary calculation of the accurate powder weight by subtracting the expansion force (derived from pressure sensor data) from the load cell reading before using this value for valve aperture and differential pressure adjustments. This preliminary correction action ensures that subsequent control decisions are based on accurate measurements, improving flow rate control precision.
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 solution enables precise control of the powder flow rate, reducing errors and ensuring accurate adjustment of the powder supply, thereby improving the overall accuracy of the powder supply process.
Implementation Method 1
a load cell (45) adapted to receive a load from the feed tank (11) to detect the load
Implementation Method 2
This expansion/contraction part is capable of expanding and contracting slightly in the vertical direction by the force of the feed tank pulling the pipe
Implementation Method 3
When the pressure in the feed tank is very high, however, the expansion/contraction part tends to expand because of its inner pressure
Data Source
AI summary
A powder supply device includes a controller configured to receive an output from a load cell and an output from a pressure indicator, wherein the controller obtains a powder weight or a rate of change in the powder weight in a feed tank on the basis of a value obtained by subtracting a value proportional to the output from the pressure indicator from the output from the load cell and controls the flow rate of the powder to be supplied to outside of the feed tank on the basis of the powder weight or the rate of change in powder weight in the state in which a closing valve is closed.