Hydrothermal Sludge Dewatering via Piston Press and Cooling
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Solution Overview
Problem
Current methods for ultra-dehydrating sewage sludge face high energy consumption, odor management issues, and automation challenges, particularly in achieving and storing sludge with at least 50% dryness without self-ignition and efficient thermal recovery.
Innovation Solution
Combining hydrothermal carbonization with a piston press, where products are pressurized and thermally conditioned in a closed reactor, followed by dehydration using a piston press, with odor control measures to prevent atmospheric diffusion and automate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal drying is used to achieve ultra-dehydration of sludge, then dryness greater than 50% is obtained, but energy consumption increases to 900-1100 kWh/TEE
Solution Approach 1:
The dehydration process is divided into two distinct stages: a first dehydration stage using a filter press to achieve initial dewatering (4-25% dryness), and a second ultra-dehydration stage using thermal drying to achieve final dryness (>50%). This segmentation allows each stage to operate optimally, reducing overall energy consumption compared to direct thermal drying.
Solution Approach 2:
The filter press performs preliminary dehydration before thermal drying, removing a significant portion of water content upfront. This preliminary action reduces the water load on the thermal dryer, thereby reducing the energy required for the subsequent ultra-dehydration stage.
2Extent of automation
If filter press is used for dewatering, then automation is difficult, but if thermal drying is used, then automation is easier
Solution Approach 1:
The filter press and thermal drying unit are merged into an integrated system where the filter press handles initial dewatering and the thermal dryer completes ultra-dehydration. This combination allows the automated thermal drying unit to handle the complex ultra-dehydration task while the filter press handles preliminary processing, achieving both automation and effective dewatering.
3Reliability
If sludge is stored with high dryness content, then self-ignition risk decreases, but storage complexity increases
Solution Approach 1:
The dryness content parameter of sludge is changed from low (conventional) to high (>50%, preferably 65% or more) through the two-stage dehydration process. This parameter change fundamentally alters the storage characteristics, eliminating self-ignition risks and enabling long-term stable storage without complex safety management systems.
4Quantity of substance
If direct thermal drying is used, then ultra-dehydration is achieved, but odor release into atmosphere occurs
Solution Approach 1:
The dehydration process is segmented into a filter press stage and a thermal drying stage, with each stage operating in a controlled manner. The thermal drying unit, being a closed system, handles the ultra-dehydration while containing odors, and the filter press handles preliminary dewatering separately, reducing overall odor emission into the atmosphere.
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
Significantly reduces energy consumption, effectively manages odors, and enables automated production and storage of ultra-dehydrated sludge with improved dryness and thermal recovery, while preventing self-ignition and odor spread.
Implementation Method 1
dehydration of the products by piston press
Implementation Method 2
dehydration of the products by piston press, until a dryness greater than 50% is obtained
Implementation Method 3
the temperature of the product upstream of dehydration by piston press being regulated by cooling between 40 and 90°C
Implementation Method 4
hydrothermal carbonization type treatment, including pressurization and thermal conditioning for residence in a closed reactor
Implementation Method 5
hydrothermal carbonization of dehydrated sludge
Implementation Method 6
followed by decompression, then dehydration of the products by piston press
Data Source
Figure 1
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Figure 3~4
AI summary
The invention relates to a method for ultra-dehydrating thickened or pasty biomass products, in particular sludge from wastewater treatment plants, according to which the products, in particular products having a dryness of 4 % to 25 %, are subjected to the following steps: hydrothermal carbonisation treatment, including pressurization (1, 2) and thermal conditioning (30) for a duration in a closed reactor (4); followed by dehydration of the products by a ram press (12), obtaining a dryness of more than 50 %; the temperature of the product upstream from the ram press dehydration being regulated by cooling between 40 °C and 90 °C, advantageously to around 70 °C, in order to optimise the filterability in the piston press; the steps of the method being performed in a confined space making it possible to prevent the release of smells into the atmosphere.