Continuous Thermal Hydrolysis of High Dryness Sludge
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Solution Overview
Problem
Current thermal hydrolysis processes for sludge treatment face challenges with high dryness sludges, including incomplete steam injection, inefficient energy consumption, and maintenance issues with conventional heat exchangers, which limit the effectiveness and efficiency of anaerobic digestion.
Innovation Solution
A continuous thermal hydrolysis process involving a destructuring step using a dynamic mixer to break the sludge structure and reduce viscosity, followed by heating in a sludge/sludge heat exchanger that recovers heat from hydrolyzed sludge without an intermediate fluid, optimizing fluidity and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heat exchangers are used to cool hydrolyzed sludge, then cooling function is provided, but maintenance difficulty increases and operational reliability decreases due to fouling and clogging
Solution Approach 1:
The patent introduces an intermediary fluid (water or another liquid) that circulates through the heat exchanger to absorb heat from the hydrolyzed sludge. This intermediary fluid acts as a mediator between the sludge and the cooling system, preventing direct contact between sludge and heat exchanger surfaces, thereby eliminating fouling and clogging issues while maintaining effective cooling
Solution Approach 2:
The cooling system is segmented into separate circulation circuits: a first circuit for the intermediary fluid and a second circuit for the hydrolyzed sludge. This segmentation allows independent operation and maintenance of each circuit, improving reliability by isolating the heat exchanger from sludge-related fouling problems
2Use of energy by moving object
If sludge concentration is increased to reduce water content, then energy consumption for heating decreases, but steam injection effectiveness deteriorates and mixing becomes difficult
Solution Approach 1:
The patent applies preliminary mechanical agitation and steam injection to the sludge before thermal hydrolysis treatment. This preliminary action reduces sludge viscosity and improves fluidity in advance, ensuring that even concentrated sludge with high dryness (up to 50% or more) can be effectively mixed and injected with steam during subsequent heating, thereby enabling energy-efficient treatment of highly concentrated sludge
3Reliability
If batch treatment process is used, then treatment completeness is improved, but productivity decreases and equipment wear increases due to repetitive operations
Solution Approach 1:
The patent implements a continuous thermal hydrolysis process where sludge is continuously fed into the reactor, continuously heated, and continuously discharged. This continuous operation eliminates the start-stop cycles of batch processes, maintaining constant treatment conditions for complete hydrolysis while significantly increasing productivity and reducing equipment wear from repetitive valve operations and cycle transitions
4Use of energy by moving object
If thermal hydrolysis is applied to sludge with high dryness, then energy efficiency improves, but steam injection completeness deteriorates
Solution Approach 1:
The patent applies preliminary mechanical agitation and steam injection to high-dryness sludge before thermal hydrolysis to reduce viscosity and improve fluidity. This preliminary action ensures that even sludge with 50% or higher dryness can be effectively mixed and penetrated by steam during hydrolysis, maintaining both energy efficiency and treatment completeness
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
This approach allows for efficient treatment of sludges with high dryness, significantly reducing energy consumption and pressure drops, while facilitating maintenance and improving the fluidity of sludge, thereby enhancing the anaerobic digestion process.
Implementation Method 1
introducing said sludge to be treated into a dynamic mixer; and in heating said sludge coming from said dynamic mixer
Implementation Method 2
heating said sludge coming from said dynamic mixer, this heating being obtained by introducing into a heat exchanger on the one hand said sludge coming from said dynamic mixer, and on the other hand said hydrolyzed sludge, this inducing said cooling
Implementation Method 3
thermal hydrolysis processes. This heat treatment is generally carried out under pressure at a temperature above 100° C., and in practice possibly up to 220° C., for a predetermined period of time
Data Source
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AI summary
The invention relates to a method for the continuous thermal hydrolysis of sludge to be treated containing organic matter, and to a facility for implementing said method, said method comprising at least: a. a step of destructuring said sludge to be treated, producing destructured sludge; b. a step of thermal hydrolysis of said destructured sludge in a thermal hydrolysis reactor, producing hydrolysed sludge; and c. a step of cooling said hydrolysed sludge. According to the invention, said destructuring step consists in: introducing said sludge to be treated into a dynamic mixer; and heating said sludge from said dynamic mixer, the heating being generated by introducing, into a heat exchanger, both said sludge from the dynamic mixer and said hydrolysed sludge, this then inducing said cooling.