Two-Stage Fogging System for Gas Turbine Air Inlet Humidity Control
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Solution Overview
Problem
Current air inlet cooling systems for gas turbines and diesel engines are inefficient, particularly at high ambient temperatures, leading to power loss and increased fuel consumption, with existing solutions like cooling coils and fogging systems being complex, costly, and requiring frequent shutdowns for maintenance, and introducing water into the air stream which can cause humidity and pressure issues.
Innovation Solution
A two-stage fogging system is implemented, with a high-capacity first stage upstream of air filters using rotary atomizers to control relative humidity and a low-capacity second stage downstream, utilizing a closed-loop control system to adjust water flow and prevent filter differential pressure spikes, allowing for precise humidity management and reduced water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fogging systems are located downstream of inlet filters, then filter performance is maintained, but the system requires a large number of high pressure nozzles and cannot be easily modified or repaired
Solution Approach 1:
The fogging system is divided into two separate stages: a first stage located upstream of the inlet filter and a second stage located downstream of the inlet filter. This segmentation allows each stage to have fewer nozzles and different functional requirements, reducing overall system complexity while maintaining filter performance protection.
Solution Approach 2:
The inlet filter serves as an intermediary element between the two fogging stages. The first stage fogging occurs upstream where the filter protects downstream equipment from water droplets, while the second stage fogging occurs downstream where the filter has already done its protective work. This intermediary role of the filter enables the dual-stage approach.
2Reliability
If fogging systems use demineralized water, then nozzle calcification is avoided, but water cost and availability issues arise
Solution Approach 1:
Different water quality requirements are applied to different stages: the first stage upstream of the filter can use lower quality water (such as seawater or process water) because the filter protects downstream equipment from droplet contamination, while the second stage downstream uses higher quality water to prevent nozzle calcification. This local quality differentiation reduces overall water quality constraints.
3Temperature
If cooling coils are installed, then inlet air temperature is reduced, but system cost and complexity increase
Solution Approach 1:
The system uses evaporative cooling through water droplet phase transition from liquid to vapor. Water is sprayed as fine droplets into the hot inlet air stream, where they evaporate and absorb heat, cooling the air without requiring mechanical cooling coils or complex refrigeration systems. This phase transition approach provides simple, effective cooling.
4Temperature
If media-type evaporative coolers are installed, then temperature reduction is achieved, but the system cannot be adjusted for ambient condition changes and requires shutdown for maintenance
Solution Approach 1:
The fogging system is designed to be dynamically adjustable to ambient conditions. Water flow rates to the nozzles can be varied based on ambient temperature, humidity, and gas turbine load requirements. The system can be quickly modified or repaired without shutdown by isolating and replacing individual nozzle assemblies, providing both operational flexibility and maintenance accessibility.
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 maintains optimal relative humidity levels, prolongs filter life, and enhances gas turbine efficiency by achieving up to 90% of air cooling potential without affecting filtration performance, reducing the need for demineralized water, and minimizing hardware in the clean air duct, thus avoiding unscheduled shutdowns and reducing capital expenses.
Implementation Method 1
The introduced water droplets may then evaporate into the air, which creates a new equilibrium - a lower temperature and a higher relative humidity
Implementation Method 2
From any given starting point, the system enthalpy remains unchanged; and, a temperature between the initial ambient temperature and the corresponding wet bulb temperature may be achieved by limiting the amount of water available
Data Source
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AI summary
The present embodiments disclose a method of running an air inlet system upstream of one or more inlet air filters of a device protected by air filtration, wherein the method comprises: regulating the relative air humidity of the inlet air at the one or more inlet air filters in dependence of the inlet air filters differential pressure.