Sorption Dryer Recirculation Cooling for High-Humidity Dehumidification
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Solution Overview
Problem
Existing sorption drying systems face inefficiencies in dehumidification due to temperature increases from latent heat absorption and regeneration, which impair the absorption capacity of the drying agent and require additional cooling gas streams, reducing system performance, especially at high air humidities.
Innovation Solution
A sorption drying system that recirculates and cools a portion of the dehumidified gas stream to lower the temperature of the absorbent mass, allowing for more efficient moisture absorption and reducing additional moisture input, while optimizing the balance between cooled and moist gas streams to enhance drying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heated regeneration gas stream passes through the drying agent to remove absorbed moisture, then the drying agent's absorption capacity is restored, but the temperature of the drying agent increases, impairing its absorption capacity
Solution Approach 1:
The drying wheel is divided into multiple sectors with different functions: a drying sector for moisture absorption, a regeneration sector for heating and moisture removal, and a cooling sector for temperature reduction. This segmentation allows the drying agent to undergo sequential processes without all functions occurring simultaneously in the same zone, thereby managing temperature effects on absorption capacity.
Solution Approach 2:
The cooling gas is introduced into the drying agent in the cooling sector before the drying agent re-enters the drying sector. This preliminary cooling action reduces the temperature of the drying agent before it resumes moisture absorption, thereby restoring its absorption capacity that was impaired by the preceding regeneration heating process.
2Reliability
If a separate cooling gas stream is introduced to cool the drying agent, then the absorption capacity is improved, but additional equipment and flow paths are required, increasing system complexity
Solution Approach 1:
The drying wheel structure serves multiple functions through its segmented sectors: it performs drying, regeneration, and cooling operations in sequence using the same physical structure. The drying agent bed itself acts as both the processing medium and the heat transfer medium, eliminating the need for separate cooling equipment and reducing overall system complexity.
Solution Approach 2:
The system uses a portion of its own output (dehumidified air) as the cooling medium in the cooling sector. This self-service approach eliminates the need for external cooling sources or additional cooling gas streams, thereby simplifying the system while still achieving the cooling function necessary to restore absorption capacity.
3Reliability
If the cooling sector is used to cool the drying agent, then the absorption capacity is improved, but the available sector for drying is reduced, impairing the capacity of the drying wheel
Solution Approach 1:
The drying wheel rotates continuously, allowing different sectors to perform their functions in sequence without interruption. The drying agent continuously cycles through the drying sector (where it absorbs moisture), regeneration sector (where it is heated and dried), and cooling sector (where temperature is reduced). This continuous cyclic operation ensures that while one sector is performing a non-drying function, other sectors are actively drying, maintaining overall drying capacity.
Solution Approach 2:
The drying wheel operates on a periodic cycle where each sector performs its designated function at regular intervals determined by the rotation speed. The drying agent experiences periodic cycles of absorption, regeneration, and cooling as it rotates through the different sectors. This periodic action allows the system to balance the competing requirements of maintaining absorption capacity while preserving drying capacity through proper timing and sector sizing.
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 improves the drying performance by maintaining a lower, more optimal temperature for dehumidification, increasing the absorption capacity of the absorbent mass and reducing energy consumption, even at elevated flow rates, without the need for additional cooling gas streams.
Implementation Method 1
The drying wheel contains a mass of absorbing or sorptive material (drying agent) that removes moisture from the gas stream by the vapour being absorbed
Implementation Method 2
upon absorption of vapour, latent heat in the gas stream is converted into sensible heat, i.e., the evaporation energy in absorption increases the temperature of the gas and drying agent
Implementation Method 3
a heated gas stream passes through the drying wheel in an area separated from the passage of the moist gas stream. The heated air regenerates the drying wheel continuously
Implementation Method 4
regeneration, i.e., that a heated gas stream passes through the drying wheel
Implementation Method 5
a cooler for cooling the deflected dehumidified gas stream
Implementation Method 6
at least a part of the cooled deflected dehumidified gas stream being arranged to flow through the absorbent mass in a channel separated from the moist gas stream
Data Source
AI summary
Sorption drying system for dehumidification of a moist gas stream, comprising a mass (1) of absorbing material, a moist gas stream (2) arranged to flow through at least a part of the absorbent mass, and a heated stream of regeneration gas (3) arranged to flow through at least a part of the absorbent mass. The sorption drying system further comprises means (4) for deflecting a part of the dehumidified gas stream after flowing through the absorbent mass, a cooler (5) for cooling the deflected dehumidified gas stream, and means (6; 7) for returning the cooled deflected dehumidified gas stream to the moist gas stream at the inlet into the absorbent mass. At least a part of the cooled deflected dehumidified gas stream is arranged to flow through the absorbent mass in a channel separated from the moist gas stream.