Sewage Sludge Drying via Weight-Responsive Solids 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 inaccurate moisture content determination and inefficient drying methods, leading to objectionable odors and handling difficulties.
Innovation Solution
A system that uses a treatment container with weight-responsive members to measure solids content and apply heat, allowing for precise moisture reduction and chemical treatment, such as lime addition, with computer-controlled operations for batch, pulsed, or continuous processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing drying apparatus evaporate water until product becomes very dry (excess of 90% dry solids), then moisture content is reduced, but the end product becomes dusty and difficult to handle
Solution Approach 1:
The patent employs weight-responsive members (load cells) that continuously monitor the weight of the sludge material during drying. This real-time feedback allows the system to precisely determine when the desired solids concentration (10-99%) is achieved, preventing over-drying that would cause dusting and handling difficulties. The computer control system uses this weight data to automatically adjust or terminate the drying process.
Solution Approach 2:
The patent replaces indirect moisture determination methods (timers, temperature monitoring) with direct weight measurement using load cells. This substitution provides accurate real-time data on moisture content, enabling precise control of the drying process to achieve the optimal balance between moisture reduction and product handleability.
2Volume of stationary object
If batch processing container is filled to full capacity, then processing volume is maximized, but as moisture is drawn off the volume reduces and less rotor surface area contacts the material
Solution Approach 1:
The patent makes the rotor system dynamic by allowing it to adjust its position or operation based on the changing volume of material. As moisture is removed and material volume decreases, the system can adjust rotor speed, position, or configuration to maintain optimal contact and heat transfer surface area throughout the batch process, preventing productivity decline.
Solution Approach 2:
The patent ensures continuous effective contact between heated rotors and material by adjusting the drying process to maintain optimal rotor-material interaction throughout the batch. This may involve varying rotor speed or position to compensate for volume reduction, ensuring the drying action remains effective and continuous rather than diminishing as the batch progresses.
3Device complexity
If indirect measurements or timers are used to estimate moisture content, then measurement simplicity is maintained, but the solids content determination lacks precision
Solution Approach 1:
The patent replaces complex indirect moisture measurement methods (thermal conductivity, dielectric sensing) or simple timers with direct weight measurement using load cells. This substitution provides accurate, real-time data on moisture content while maintaining relatively simple system architecture, achieving both precision and practicality.
4Temperature
If heat is applied until temperature increases substantially indicating moisture removal, then drying completion is detected, but the product becomes extremely dry and difficult to handle
Solution Approach 1:
The patent uses weight-responsive members to provide real-time feedback on the actual moisture content and solids concentration of the sludge during drying. This feedback allows the control system to terminate the heating process at the precise moment when the desired solids concentration (10-99%) is achieved, preventing over-drying that would make the product difficult to handle, while still using temperature as a control parameter.
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
Produces a sewage sludge end product with a predetermined solids concentration between 10% and 99%, reducing odors, dust, and improving handling characteristics by accurately controlling moisture content and processing conditions.
Implementation Method 1
one or more weight-responsive members are used to determine the solids content of the material being treated, at any given time, by measuring the difference in weight of material in the container before and after moisture is drawn off from the material
Implementation Method 2
moisture gases principally water, is, drawn off and evaporated
Implementation Method 3
heat is applied to the material being treated
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.