Sludge-Cement Mixture Drying via Low-Temperature Exhaust Heat
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Solution Overview
Problem
In the cement production process, low-temperature exhaust heat is typically discarded, rather than being utilized as energy, which limits the efficiency of heat utilization.
Innovation Solution
A method and system that mix dehydrated sludge with cement raw meal and use low-temperature exhaust gas from the cement production process to dry the mixture, with the dried mixture being used as fuel and raw meal in the pyroprocessing step, and the exhaust gas from the drying process being used for cooling and combustion, thereby efficiently utilizing the low-temperature heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-temperature exhaust heat is discarded to the atmosphere, then the cement production process is simple, but heat utilization efficiency is poor
Solution Approach 1:
The system uses its own low-temperature exhaust heat to dry the sludge-cement raw meal mixture, creating a self-service heating system that eliminates waste heat discharge and improves overall heat utilization efficiency without requiring external energy sources
Solution Approach 2:
The invention recovers the previously discarded low-temperature exhaust heat from the cement production process and reuses it for drying sludge, transforming waste energy into a useful resource for improving heat utilization efficiency
2Loss of energy
If dehydrated sludge is dried using low-temperature exhaust gas, then heat utilization efficiency is improved, but drying efficiency is insufficient
Solution Approach 1:
The invention combines dehydrated sludge with cement raw meal to form a mixture before drying, which improves the drying efficiency by creating a more favorable heat transfer surface and structure, allowing effective drying even with low-temperature exhaust gas
Solution Approach 2:
The invention changes the physical state and composition parameters of the sludge by mixing it with cement raw meal, transforming it from a difficult-to-dry material into a mixture that can be effectively dried using low-temperature exhaust gas while maintaining productivity
3Productivity
If sludge is dried without mixing with cement raw meal, then the process is simple, but drying efficiency and heat utilization are poor
Solution Approach 1:
The invention merges dehydrated sludge with cement raw meal into a combined mixture that is then dried together, improving drying efficiency by creating a composite material with better heat transfer characteristics and simultaneous utilization of the cement raw meal in the pyroprocessing step
Solution Approach 2:
The mixture of sludge and cement raw meal serves multiple functions: it acts as the drying material, the fuel for pyroprocessing, and the raw meal for cement production, eliminating the need for separate handling processes and improving overall system efficiency
4Productivity
If high-temperature gas is used for drying, then drying efficiency is high, but sulfur dioxide and hydrogen sulfide generation increases causing corrosion
Solution Approach 1:
The invention changes the temperature parameter of the drying gas from high-temperature to low-temperature range, which suppresses the thermal decomposition of sulfur compounds in sludge, thereby reducing sulfur dioxide and hydrogen sulfide generation and preventing corrosion while maintaining effective drying through the sludge-cement raw meal mixture approach
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 the effective drying of sludge using low-temperature exhaust heat, eliminates the need for separate deodorizing devices, suppresses sulfur dioxide and hydrogen sulfide generation, and maintains gas balance in the cement production process, leading to stable operation and reduced corrosion.
Implementation Method 1
drying the mixture by a dryer that brings the mixture into contact with drying gas
Implementation Method 2
utilize the low-temperature (e.g., lower than 200°C) exhaust heat from the cement production process to dry dehydrated sludge
Implementation Method 3
a high-temperature pyroprocessed product exiting from cement pyro-process equipment is rapidly cooled by an air quenching cooler. In the air quenching cooler, cool air is fed to the high-temperature pyroprocessed product to rapidly cool it down
Data Source
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AI summary
A sludge treatment method includes: preparing a mixture by mixing dehydrated sludge and cement raw meal; drying the mixture by a dryer that brings the mixture into contact with drying gas; supplying the dried mixture to a pyroprocessing step of a cement production process as a fuel and raw meal; supplying exhaust gas from the dryer to the pyroprocessing step as cooling gas for cooling a pyroprocessed product; and supplying the drying gas to the dryer, the drying gas being either exhaust gas from the cement production process or exhaust gas from a process that utilizes heat thereof, the drying gas having a temperature of not lower than 50°C but lower than 200°C.