Batch Distillation Pressure Regulation to Reduce Heat-Pump Compressor Power
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Solution Overview
Problem
Centrifugal compressors in distillation devices face challenges when the required heating temperature of the reboiler changes over a wide range, leading to inefficient operation and increased power consumption due to mismatched flow rates and pressure changes, which affects the energy-saving potential of heat pump systems.
Innovation Solution
A distillation method that includes a pressure-regulating step to adjust the pressure of the distillation column, using either an indirect or direct heat pump mechanism, to minimize the temperature pumping range and optimize compressor power usage by narrowing the temperature rising range during the pressure-temperature increasing step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the compression ratio of the centrifugal compressor is set to cover the entire changing range of required heating temperature of the reboiler, then the temperature pumping range of the heat pump covers the entire range, but the actual volume flow rate becomes less than the designed flow rate and may be excluded from the normal operation range
Solution Approach 1:
The patent applies dynamics by making the compression ratio variable rather than fixed. The compression ratio is dynamically adjusted according to the changing heating temperature requirements of the reboiler during batch distillation. This allows the compressor to maintain optimal operating conditions across different temperature ranges while keeping the actual volume flow rate within the normal operation range (above 80% of designed point).
Solution Approach 2:
The patent changes the compression ratio parameter based on the required heating temperature. By adjusting this key parameter, the system adapts to different operating conditions without sacrificing volume flow rate. The compression ratio is modified in response to temperature changes, ensuring both adaptability and maintained productivity.
2Temperature
If the suction pressure of the compressor is increased to increase the discharge pressure and temperature, then the temperature pumping range becomes narrower, but the increased pressure increases the density of the fluid and reduces the actual volume flow rate
Solution Approach 1:
The patent dynamically adjusts the compression ratio rather than maintaining a fixed high suction pressure. This dynamic adjustment allows the system to achieve required discharge temperatures while preventing excessive pressure increases that would reduce volume flow rate below acceptable levels.
3Power
If the impeller shape of the centrifugal compressor is designed for specific components and flow rate at the designed point, then the compressor operates efficiently at the designed point, but when components and flow rate change, the predetermined pressure increasing capacity may not be obtained
Solution Approach 1:
The patent makes the compression ratio dynamic to compensate for changes in fluid composition and flow rate. When these parameters change during operation, the compression ratio is adjusted accordingly to maintain the required pressure increasing capacity, overcoming the limitation of a fixed impeller design.
4Reliability
If a kickback line is used to maintain the inlet actual volume flow rate at 80% of the designed point, then the compressor operates in normal range, but the compressor has to be operated in a power-increased state to cope with the circulated amount of fluid
Solution Approach 1:
The patent dynamically adjusts the compression ratio to maintain optimal operating conditions without requiring kickback circulation. By doing so, it avoids the additional power consumption associated with circulating fluid through a kickback line while keeping the compressor within its normal operation range.
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
The method allows for efficient distillation with reduced compressor power requirements and improved energy efficiency by regulating pressure to match the changing heating demands of the reboiler, enhancing the energy-saving effect of the heat pump system.
Implementation Method 1
the liquid supplied to the distillation column is hydrous ethanol containing trace methanol... water vapor, increased in pressure and temperature by the compressor, is supplied to the condenser (reboiler of distillation device)
Implementation Method 2
The temperature of the water vapor supplied to the condenser (reboiler of distillation device) is set to be higher than the temperature of the hydrous ethanol at the bottom of the distillation column. Thus, the water vapor entering the condenser (reboiler of distillation device) transfers heat to the hydrous ethanol and condenses.
Implementation Method 3
The temperature of the water delivered to the evaporator (condenser of distillation device) is set to be lower than the temperature of the contaminated alcohol vapor. Thus, the contaminated alcohol vapor condenses as it transfers heat to the water
Implementation Method 4
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 reboiler
Data Source
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AI summary
A distillation method includes a supplying step of supplying a batch type distillation column with a liquid that is a process fluid; a pressure-temperature increasing step of increasing pressure and temperature of a fluid, used to heat the liquid, with a compressor and supplying the fluid to a reboiler; a heating step of exchanging heat in the reboiler between the liquid, which has been supplied to the distillation column, and the fluid, which has been increased in pressure and temperature, to heat the liquid and acquire overhead vapor and to condense the fluid; a condensing step of delivering the overhead vapor heated in the heating step to a condenser and condensing the overhead vapor into a condensate through heat exchange; a distillate removing step that removes the condensate; and a discharged liquid removing step that removes residual liquid from the distillation column. A pressure-regulating step regulates pressure of the distillation column to distill the liquid with heat generated by a heat pump operated over a narrower temperature rising range in the pressure-temperature increasing step.