Buffer Tank Exhaust System for Hydrogen Dilution
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Solution Overview
Problem
Conventional exhaust systems face challenges in diluting hydrogen gas to concentrations below the lower explosive limit without increasing pressure in buffer tanks, leading to potential contamination of EUV exposure equipment and high costs due to excessive use of dilution gases.
Innovation Solution
An exhaust system with a buffer tank designed to introduce exhaust gases tangentially, allowing hydrogen gas to remain in the upper part while heavier gases diffuse to the bottom, and controlled valve operations to selectively discharge gases, reducing the need for large amounts of dilution gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If exhaust gas is introduced into the buffer tank to dilute hydrogen gas, then hydrogen gas concentration is reduced below the lower explosive limit, but pressure in the buffer tank increases excessively
Solution Approach 1:
The buffer tank is divided into multiple discharge ports positioned at different heights. The lower discharge port discharges heavier gases (oxygen, nitrogen) while the upper discharge port discharges lighter hydrogen gas. This segmentation allows selective discharge of different gas components based on their density, enabling pressure control while maintaining safe hydrogen concentration levels.
Solution Approach 2:
Different regions of the buffer tank are assigned different functions based on gas density stratification. The lower region handles discharge of heavier gases through the lower discharge port, while the upper region handles hydrogen gas discharge through the upper discharge port. This local quality differentiation enables efficient gas separation and pressure management.
2Quantity of substance
If large amount of dilution gas is supplied to reduce hydrogen gas concentration, then safety is improved, but cost increases due to excessive gas consumption
Solution Approach 1:
The system utilizes the natural density difference between hydrogen gas and other exhaust gases to achieve automatic separation and discharge. Heavier gases naturally settle at the bottom and are discharged through the lower port, while lighter hydrogen gas rises and is discharged through the upper port. This self-service mechanism eliminates the need for additional dilution gas supply, reducing operational costs while maintaining safety.
3Device complexity
If conventional exhaust system operates without selective gas discharge, then system complexity is reduced, but equipment contamination occurs due to pressure increases
Solution Approach 1:
The exhaust system is segmented into multiple discharge pathways with different discharge ports positioned at specific heights in the buffer tank. This segmentation enables selective discharge of different gas components, preventing pressure buildup that could cause backflow and contamination of upstream equipment, while maintaining relatively simple system architecture.
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
Effectively dilutes hydrogen gas to concentrations below the lower explosive limit while minimizing pressure increases in buffer tanks, reducing the amount of dilution gas required and preventing equipment contamination, thus enhancing safety and cost-effectiveness.
Implementation Method 1
heavier gases diffuse to the bottom
Implementation Method 2
heavier gases diffuse to the bottom
Data Source
AI summary
An exhaust system capable of diluting a hydrogen gas to a concentration below the lower explosive limit without requiring a large amount of dilution gas while preventing an increase in a pressure of an exhaust gas in a buffer tank is disclosed. The exhaust system performs, when a main valve disposed in an exhaust line is closed, an initial exhaust operation in which a gas heavier than the hydrogen gas is discharged from a lower part of a buffer tank while an inlet valve disposed in an inlet line and a first outlet valve disposed in an outlet line are opened to introduce the exhaust gas from an equipment in a tangential direction of a buffer tank. Next, the exhaust system performs a hydrogen-gas discharge operation in which the inlet valve and the first outlet valve are closed, and the a bypass valve disposed in a bypass line and the second outlet valve disposed in a hydrogen-gas discharge line are opened to discharge the hydrogen gas stayed in an upper part of the buffer tank while flowing the exhaust gas into a bypass line.