Vacuum Drying of Sludge via Pressure Control
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Solution Overview
Problem
Existing methods for drying sludge, such as sewage sludge, face challenges including high energy consumption, pollution from odor emissions and toxic substances, and difficulties in handling sticky pasty materials, which complicates the drying process and incineration.
Innovation Solution
A method that maintains the vapor space in the drying system at a pressure close to the saturation vapor pressure of the liquid, using a gas-tight container system with a condenser and vapor space, where pressure and temperature are monitored and controlled to optimize drying efficiency with low energy consumption, and incorporates a carrier material to reduce stickiness and promote surface area for drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fluidized bed dryer with hot air blower is used to dry pasty sludge, then drying efficiency is improved, but strong adhesions form on system surfaces and odor emissions increase
Solution Approach 1:
The patent applies vacuum drying to create an inert environment by removing air from the drying chamber. This eliminates oxygen that would otherwise support combustion and reduce odors, while the vacuum condition prevents adhesion of pasty sludge to surfaces. The inert atmosphere achieved through vacuum conditions resolves the contradiction between drying efficiency and harmful emissions.
Solution Approach 2:
The patent utilizes phase transition of water from liquid to vapor through evaporation under vacuum conditions. By controlling the phase change of moisture in the sludge, the system achieves effective drying without requiring high-temperature hot air that causes adhesion and odor emissions, thus resolving the technical contradiction.
2Productivity
If incineration at high temperature is used to treat wet material, then drying is achieved, but pollutants such as heavy metals are released
Solution Approach 1:
The vacuum drying system creates an inert atmosphere that prevents combustion and release of heavy metals. By operating under vacuum without atmospheric oxygen, the process avoids incineration-related pollution while still achieving drying through controlled evaporation, thus resolving the contradiction between drying capability and pollutant emissions.
Solution Approach 2:
The patent changes the operating parameters from atmospheric pressure incineration to vacuum pressure drying. This parameter change allows drying to occur at lower temperatures without releasing pollutants, resolving the contradiction between effective drying and harmful emissions.
3Reliability
If pressure in vapor space is too high, then condenser efficiency decreases, but energy consumption increases
Solution Approach 1:
The patent employs pressure sensors and controllers that continuously monitor and adjust the vacuum pressure in the drying chamber. This feedback control maintains optimal pressure conditions for condenser efficiency while minimizing energy consumption by avoiding excessive vacuum levels, thus resolving the contradiction between condenser reliability and energy use.
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 reduces energy consumption, minimizes odor emissions, and effectively handles sticky sludge without releasing pollutants, achieving efficient and environmentally friendly drying with improved handling and productivity.
Implementation Method 1
a condenser (3) for condensing the vaporized liquid (Fd) to condensate (5)
Implementation Method 2
The vapor space (6) connects the drying container (2) to the condenser (3). It is filled with the vapor Dk to be condensed. This vapor Dk was created by evaporating the liquid Fd to be distilled from the drying container (2)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for drying a wet material (4) which comprises a liquid Fd to be distilled, using a gas-tight container system (1) that is resistant to excess and/or negative pressure. Said container system comprises a drying container (2) containing the wet material (4) whose temperature can be adjusted, a condenser (3) for condensing the liquid Fd, which has turned to vapor and whose temperature can be adjusted, to give the condensation product (5), and a vapor chamber (6) connecting the drying container (2) and the condenser (3). The aim of the invention is to make sure that the vapor in the vapor chamber (6) is free of foreign gas except for a tolerated remainder. To achieve this aim, the pressure in the vapor chamber (6) is monitored and controlled in such a manner that drying and distillation are always carried out in a range close to the saturation vapor pressure of the liquid Fd to be distilled. For this purpose, the pressure and the temperature in the vapor chamber (6) have to be continuously determined. If the pressure is too high, it is reduced in such a manner that especially foreign gas is removed.