Batch Distillation Heat Pump Control for Variable Reboiler Temperature
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Solution Overview
Problem
Centrifugal compressors in existing distillation devices struggle to maintain efficient operation when the required heating temperature of the reboiler changes over a wide range, leading to reduced actual volume flow rates and increased power consumption, as they are designed for constant fluid flow and pressure conditions.
Innovation Solution
The distillation device employs a displacement compressor with an actual volume flow rate regulation mechanism, allowing the actual volume flow rate to be adjusted in accordance with changes in the required heating temperature of the reboiler, using either a step displacement control system or a stepless displacement control system to optimize the temperature pumping range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a centrifugal compressor is used to increase pressure and temperature of the working fluid, then the fluid can be supplied to the reboiler for heating, but the actual volume flow rate decreases when the suction pressure is increased to cover a wide temperature range
Solution Approach 1:
The patent applies dynamics by making the compression ratio of the centrifugal compressor adjustable rather than fixed. The compression ratio is dynamically changed according to the required heating temperature of the reboiler, allowing the system to adapt to varying temperature requirements while maintaining optimal fluid flow rates. This resolves the contradiction by enabling the compressor to operate efficiently across a wide temperature range without sacrificing volume flow rate.
2Adaptability or versatility
If the compression ratio is increased to cover the entire changing range of required heating temperature, then the temperature pumping range of the heat pump can cover the full range, but the actual volume flow rate becomes less than the designed flow rate
Solution Approach 1:
The system dynamically adjusts the compression ratio based on the specific heating temperature requirements. When the reboiler requires higher temperatures, the compression ratio is increased accordingly, rather than maintaining a constantly high compression ratio. This dynamic adjustment maintains adaptability across the full temperature range while preserving the actual volume flow rate within the designed operational range.
Solution Approach 2:
The patent changes the operational parameters of the centrifugal compressor, specifically the compression ratio, to match the required heating temperature. By adjusting this parameter dynamically, the system achieves both wide temperature adaptability and maintained productivity, resolving the contradiction between these two features.
3Temperature
If the suction pressure of the compressor is increased to increase discharge pressure and temperature, then the heating temperature range can be covered, but the density of the fluid increases and the actual volume flow rate decreases
Solution Approach 1:
Rather than continuously increasing suction pressure to raise discharge temperature, the system dynamically adjusts the compression ratio. This allows the compressor to achieve the required discharge temperature while maintaining optimal suction pressure levels, thereby preventing excessive fluid density increases and preserving the actual volume flow rate within acceptable ranges.
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 the required power for the compressor by minimizing the temperature pumping range, ensuring efficient operation even when the heating temperature of the reboiler varies, thus maintaining optimal distillation performance.
Implementation Method 1
a displacement compressor that draws in fluid for heating the liquid and increases the fluid in pressure and temperature, and supplies the fluid to the reboiler
Implementation Method 2
The fluid holds condensation heat of the overhead vapor, is increased in pressure and temperature by the compressor, and then transfers the condensation heat to the liquid and condenses in the reboilers
Implementation Method 3
The condenser condenses overhead vapor of the distillation column into a condensate
Data Source
AI summary
A distillation device includes a batch type distillation column, a reboiler that heats and vaporizes liquid, which is a process fluid supplied to the distillation column, into vapor, a displacement compressor that draws in fluid for heating the liquid and increases the fluid in pressure and temperature, and supplies the fluid to the reboiler, a condenser that condenses overhead vapor of the distillation column into a condensate, a distillate withdrawal portion that removes the condensate condensed by the condenser, and a discharged liquid withdrawal portion that removes residual liquid from the distillation column. The compressor includes an actual volume flow rate regulation mechanism that varies an actual volume flow rate of the fluid, which is increased in pressure and temperature by the compressor, in accordance with a change in a required heating temperature of the reboiler during operation of the distillation device.