Cool Gas Dryer Bypass Control to Prevent Condensate Freezing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cool drying methods for gases, such as compressed air, face challenges including premature condensate freezing due to inadequate control of evaporator temperature and pressure, leading to corrosion and equipment wear, and inefficiencies in energy consumption and coolant management.
Innovation Solution
A method and device that utilize characteristic curves to setpoints for evaporator temperature or pressure, controlled by an electronic hot gas bypass valve and expansion valve, to maintain a desired lowest gas temperature, allowing for precise adjustment of cooling capacity and preventing condensate freezing, while minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the evaporator temperature is lowered to increase cooling capacity, then the gas can be cooled more effectively, but the condensate may freeze causing corrosion and equipment wear
Solution Approach 1:
The control unit continuously monitors the evaporator temperature and gas flow rate, using this feedback to dynamically adjust the electronic expansion valve position. This closed-loop control ensures the evaporator temperature is maintained above the freezing point of condensate while still achieving effective cooling of the gas.
Solution Approach 2:
The system transitions from static temperature control to dynamic control that responds to changing gas flow conditions. The electronic expansion valve continuously adjusts the coolant flow rate based on real-time gas flow measurements, allowing the system to adapt to variable loads and prevent condensate freezing during low flow conditions.
2Temperature
If the compressor speed is reduced to prevent evaporator temperature from becoming too low, then freezing is avoided, but the cooling capacity decreases and the gas cannot be cooled sufficiently
Solution Approach 1:
Instead of changing compressor speed, the system changes the coolant flow rate parameter by adjusting the electronic expansion valve. This allows independent control of evaporator temperature from the cooling capacity, enabling the system to maintain sufficient cooling while preventing freezing through precise flow rate modulation.
Solution Approach 2:
The patent replaces mechanical compressor speed control with electronic control of the expansion valve. This substitution allows for more precise and continuous adjustment of coolant flow, enabling better temperature control without sacrificing cooling capacity.
3Device complexity
If a mechanical control valve is used to prevent condensate freezing, then the system is simple, but the valve can only be fully open or fully closed causing large temperature fluctuations
Solution Approach 1:
The patent replaces the mechanical control valve with an electronic expansion valve controlled by a control unit. This electronic control system provides continuous modulation capability, eliminating the on/off operation of mechanical valves and resulting in stable coolant temperature without large fluctuations.
Solution Approach 2:
The system transitions from static on/off control to dynamic continuous control. The electronic expansion valve can assume any position between fully closed and fully open, allowing smooth adjustment of coolant flow to match varying thermal loads and maintain stable temperatures.
4Ease of operation
If the evaporator pressure is controlled to maintain certain limits, then the system operation is simplified, but during low load the condensate still freezes
Solution Approach 1:
The control unit uses feedback from both evaporator pressure sensors and gas flow rate measurements to control the expansion valve. This dual-parameter feedback ensures that during low load conditions, the system detects reduced gas flow and adjusts the coolant flow accordingly to prevent condensate freezing, while maintaining simplified pressure-based control during normal operation.
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 solution ensures stable operation by preventing condensate freezing, optimizing energy use, and maintaining efficient cooling capacity adjustments, even during variable loads, with precise control of evaporator temperature and pressure.
Implementation Method 1
water vapour in the gas is condensed by guiding the gas through the secondary section of a heat exchanger whose primary section forms the evaporator of a closed cooling circuit
Implementation Method 2
a compressor that is installed in the cooling circuit after the evaporator and which is followed by a condenser and expansion means
Implementation Method 3
a compressor that is installed in the cooling circuit after the evaporator and which is followed by a condenser
Implementation Method 4
expansion means through which the coolant can circulate
Implementation Method 5
the moisture in the gas condenses, after which the condensate is separated in a liquid separator
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Method for cool drying gas, whereby the cool dryer is characterised by curves that show the setpoint for the evaporator temperature (Tevaporator) or evaporator pressure (pevaporator) for a load ( C ) as a function of the lowest gas temperature (LATset), whereby the method comprises the following steps: - the determination of a curve and Ts et or pset as a function of the load (C) that is required to cool the gas to LATset; - the control of a supply of coolant from the compressor (6) to an injection point (P) downstream from the expansion means (8) and upstream from the compressor (6) in order to make the evaporator temperature (Tevaporator) or evaporator pressure (pevaporator) equal to Tset or pset.