Oil-Cooled Compressor Waste-Heat Recovery With On-Demand Circulation
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Solution Overview
Problem
Existing waste-heat recovery systems for oil-cooled gas compressors face challenges in supplying hot water at a requested temperature and maintaining an effective waste-heat recovery rate, especially during low compressor load factors and when the compressor is in an unload or stoppage state.
Innovation Solution
A waste-heat recovery system that includes an oil separator, a waste-heat-recovery heat exchanger, a stored hot water tank, a circulation circuit, and a control device to manage the circulation pump's operation based on temperature differences between the heat exchanger outputs and the hot water tank, ensuring efficient heat transfer and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the circulation pump operates continuously to supply hot water, then the hot water temperature can be maintained, but energy is wasted when the hot water temperature is already sufficient
Solution Approach 1:
The control device monitors the hot water temperature in real-time and uses this feedback to automatically control the circulation pump's operation. When the temperature meets the requested value, the pump stops; when it drops below the threshold, the pump restarts. This closed-loop feedback control eliminates energy waste from continuous operation while ensuring temperature maintenance.
Solution Approach 2:
The system transitions from static continuous pump operation to dynamic on-demand operation. The circulation pump's operational state changes dynamically based on real-time temperature conditions, optimizing energy consumption by operating only when necessary to maintain the requested hot water temperature.
2Loss of energy
If the circulation pump is stopped to save energy, then energy waste is reduced, but the hot water temperature cannot be maintained
Solution Approach 1:
The control device continuously monitors hot water temperature and automatically restarts the circulation pump when the temperature falls below the requested value. This feedback mechanism ensures temperature maintenance while minimizing energy consumption by operating the pump only when necessary.
Solution Approach 2:
The system uses its own temperature monitoring capability to automatically control its own operation. The control device detects temperature changes and self-regulates the circulation pump without external intervention, balancing energy savings with temperature maintenance requirements.
3Productivity
If water circulation is increased to improve heat exchange efficiency, then heat transfer rate increases, but the system complexity and energy consumption increase
Solution Approach 1:
The system uses dynamic on-demand circulation instead of continuous or fixed-rate circulation. The circulation pump operates at variable intervals based on actual temperature needs, achieving effective heat exchange only when required. This reduces unnecessary energy consumption and simplifies control compared to continuous high-rate circulation systems.
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 system effectively supplies hot water at a requested temperature and improves waste-heat recovery rates by optimizing heat exchange and reducing heat emission from the recovery apparatus, even under low load conditions.
Implementation Method 1
a waste-heat-recovery heat exchanger for recovering heat from at least either of the compressed gas flowing through the gas piping or the oil flowing through the oil piping
Implementation Method 2
a circulation pump provided at the circulation circuit
Data Source
AI summary
A waste-heat recovery system includes a compressor main body; a gas piping, a waste-heat-recovery heat exchanger, a circulation circuit, and a tank with a water inlet piping and a water outlet piping that stores water that exchanges heat with the heat medium by connecting to the circulation circuit. The waste-heat recovery system also includes an inlet valve, a circulation pump, and a gas temperature sensor that detects the temperature of the compressed gas by arranging in the gas piping. The waste-heat recovery system also includes a water temperature sensor that detects the temperature of the water in the tank, and a control device that controls the inlet valve and the outlet valve according to detection temperature of the gas temperature sensor and the water temperature sensor.