Sewage Sludge Drying Drum with Load Cell Feedback Control
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Solution Overview
Problem
Existing sewage sludge treatment processes face issues with producing a stable, non-dusty end product due to over-drying, which complicates handling and estimation of moisture content, often resulting in inefficient evaporation and handling difficulties.
Innovation Solution
A system and process that utilize weight-responsive members, such as load cells, to control the addition of sludge and chemicals, ensuring a predetermined solids concentration between 10% and 99% through precise moisture evaporation management, allowing for batch, pulsed, or continuous operations, and using computer-programmed controls for efficient thermal stabilization and chemical treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing drying apparatus evaporate water until the product becomes very dry (excess of 90% dry solids), then the sludge is stabilized, but the end product becomes extremely dusty and difficult to handle
Solution Approach 1:
The patent employs weight-responsive members (load cells) to continuously monitor the weight of the sludge material during drying. This feedback mechanism allows the system to detect when the desired solids concentration is reached and automatically stop the drying process, preventing over-drying that would cause dustiness and handling difficulties.
Solution Approach 2:
The invention changes the control parameter from indirect temperature-based estimation to direct weight-based measurement. By monitoring weight changes during evaporation, the system can precisely control the moisture content to achieve the optimal balance between stabilization and handleability, producing a non-dusty end product.
2Loss of time
If indirect measurements or timers are used to estimate moisture content, then the processing appears complete when temperature increases substantially, but the product becomes extremely dry and difficult to handle
Solution Approach 1:
The patent replaces indirect thermal measurement methods with direct gravimetric measurement using weight-responsive members. This substitution provides precise real-time data on moisture content through weight changes, eliminating the imprecision of temperature-based estimation and timer-based control.
Solution Approach 2:
The weight-responsive members automatically provide continuous feedback on the moisture content status, enabling the system to self-regulate the drying process without requiring external monitoring or intervention. The system naturally knows when to stop based on weight data.
3Quantity of substance
If batch processing is used with rotors fully submerged in material, then the container can be loaded until essentially full, but as moisture is drawn off and volume reduces, less rotor surface area contacts the material, causing reduction in evaporation rate
Solution Approach 1:
The patent introduces dynamic adjustment of rotor submersion depth based on real-time weight feedback. As moisture is evaporated and material volume decreases, the system automatically adjusts the rotor position or submersion depth to maintain optimal contact surface area, thereby sustaining high evaporation rates throughout the batch process.
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 achieves a stable, uniformly consistent end product with controlled moisture content, reducing dust and odor emissions, enhancing handling and storage by ensuring precise solids concentration and minimizing pathogen transmission risks.
Implementation Method 1
The drum is mounted on a plurality of weight-responsive members, preferably in the form of load cells
Implementation Method 2
heating and/or evaporating and/or other chemical treatment
Implementation Method 3
heat is applied to the material being treated, and wherein moisture gases, principally water, is drawn off and evaporated
Data Source
AI summary
An apparatus, method and system is provided for treating sewage sludge by heating the same in a container to drive off pathogens and/or pasteurize the sewage sludge while the material is tumbled in the container, and with moisture gases being evaporated therefrom and drawn off from the container. After treatment the treated sludge is discharged from the container. There is provided at least one weight-responsive member on which the container is mounted, and a control is provided connected to the one or more weight-responsive member whereby the solids content of the treated material can be determined by measuring the difference in weight of material in the container, before and after moisture is drawn off from the material and prior to its discharge from the drum. The control is preferably effected by means of a computer.