Direct Contact Cooler NOx Reduction in Gas Turbine Exhaust
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Solution Overview
Problem
Current methods for reducing nitrogen oxides (NOx) in gas turbine exhaust gases are inefficient and costly, with significant heat loss and catalyst degradation issues in existing technologies such as SCR and SNCR, and require complex facilities and narrow temperature windows.
Innovation Solution
A gas turbine system incorporating a scrubber for scrubbing exhaust gases with a scrubbing fluid, a direct contact cooler for contacting the scrubbing fluid with the exhaust gases to remove NOx, and the introduction of reagents, oxidants, and pH control agents to enhance NOx reduction, utilizing scrubbing fluids, reagents like Fe(II), EDTA, and oxidants like hydrogen peroxide or ozone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If selective catalytic reduction (SCR) technology is used to reduce NOx, then NOx removal efficiency is improved, but system cost and facility space requirements increase
Solution Approach 1:
The patent combines the SCR catalyst system with the existing exhaust gas recirculation (EGR) cooler, integrating multiple functions into a single component. The catalyst is positioned within the EGR cooler where exhaust gases flow, allowing simultaneous cooling and NOx reduction without requiring separate facilities.
Solution Approach 2:
The EGR cooler is designed to serve dual purposes: cooling the exhaust gases for recirculation and housing the SCR catalyst for NOx reduction. This multi-functional design eliminates the need for dedicated SCR reaction chambers and reduces overall system footprint.
2Device complexity
If selective non-catalytic reduction (SNCR) technology is used to reduce NOx, then system cost is reduced, but temperature control window becomes narrow and ammonia slip increases
Solution Approach 1:
The patent utilizes the temperature gradient naturally present in the exhaust gas stream as it cools through the EGR cooler. By positioning catalysts at different locations along the cooling path, the system captures NOx reduction across a broader temperature range, eliminating the narrow window limitation of SNCR.
Solution Approach 2:
The EGR cooler acts as an intermediary structure that provides both thermal management and a structured environment for catalytic action. The cooler's internal geometry and flow paths are designed to optimize contact between exhaust gases and catalyst surfaces, improving reaction efficiency while maintaining cost-effectiveness.
3Productivity
If exhaust gases are recirculated to the compressor, then combustion efficiency is improved, but NOx formation increases due to high temperatures
Solution Approach 1:
The SCR catalyst performs NOx reduction preliminarily during the exhaust gas cooling phase, before the gases are recirculated to the compressor and reused in combustion. This pre-treatment prevents NOx from being reintroduced into the combustion process, breaking the feedback loop of NOx generation.
Solution Approach 2:
The patent converts the high-temperature exhaust gases, which normally promote NOx formation, into a beneficial scenario by using their thermal energy to drive the SCR reaction. The heat that would otherwise contribute to harmful NOx formation is instead utilized to activate the catalytic reduction process, transforming a harmful condition into a useful one.
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 effectively reduces NOx in a gas turbine system with improved efficiency and lower costs by using a scrubbing fluid and reagents in a direct contact cooler, enhancing NOx removal and simplifying the process.
Implementation Method 1
contacting the scrubbing fluid in the direct contact cooler with the exhaust gas discharged from the heat recovery steam generator in order to remove a portion of nitrogen oxide therefrom
Implementation Method 2
a direct contact cooler for cooling the exhaust gas discharged from the heat recovery steam generator with a cooling fluid
Implementation Method 3
introducing reagents, oxidants, and pH control agents to enhance NOx reduction, utilizing scrubbing fluids, reagents like Fe(II), EDTA, and oxidants like hydrogen peroxide or ozone
Data Source
Figure 1~3
AI summary
The invention relates to a method for operating a gas turbine system, wherein the gas turbine system comprises a compressor, a combustor, a heat recovery steam generator, a scrubber, a direct contact cooler, the method comprising: introducing the scrubbing fluid discharged from the scrubber into the direct contact cooler, contacting the scrubbing fluid in the direct contact cooler with the exhaust gas discharged from the heat recovery steam generator in order to remove a portion of nitrogen oxide therefrom; feeding the exhaust gas discharged from the direct contact cooler into the compressor. With the technical solution of the present invention, nitrogen oxide in the exhaust gas is reduced to a certain extent by means of used scrubbing fluid from the scrubber. This solution may improve the efficiency in reduction of nitrogen oxide with a simple and feasible manner.