1. Healthcare
In healthcare, mixed gases serve as unobtrusive life - savers. Anesthetic mixed gases, for example, combine anesthetic agents, oxygen, and other gases with precision. This enables patients to remain pain - free and secure during surgery, facilitating seamless operations for medical professionals. Mixed gases for treating respiratory conditions typically contain a specific proportion of oxygen and helium. These can enhance patients' respiratory function, alleviating symptoms like dyspnea, which is particularly beneficial for those suffering from chronic obstructive pulmonary disease, asthma, and other respiratory disorders. For instance, an anesthetic mixture might consist of isoflurane (an anesthetic) and oxygen, with the isoflurane percentage adjusted based on the patient's condition and the nature of the surgery, usually ranging from 0.5% to 3% within the blend. The respiratory - treatment mixed gas often contains 21% - 40% oxygen and 50% - 70% helium, with trace gases maintaining stability.
2. Petrochemical Industry
Within the petrochemical sector, mixed gases are pivotal. During oil refining, gases rich in hydrogen and nitrogen find extensive use. Hydrogen can transform heavy oil into lighter products through processes such as hydrocracking and hydrofining, enhancing oil quality. Nitrogen, meanwhile, is commonly deployed for purging and displacement tasks to ensure production safety. In chemical synthesis, when producing ammonia, nitrogen and hydrogen must be mixed in a 1:3 ratio and synthesized under high temperature, high pressure, and with the aid of a catalyst. Ammonia, a vital chemical raw material, is widely utilized in industries like fertilizers, plastics, and fibers, underpinning modern industrial development. The hydrogen - nitrogen blend for ammonia synthesis typically contains 75% hydrogen and 25% nitrogen. In hydrocracking, the mixed gas may contain 80% - 95% hydrogen, with the remainder being nitrogen and trace amounts of methane.
3. Gas Appliance Experiments and Calorific Value Analysis
Gas appliance safety and performance matter in daily life. In gas appliance experiments, specific mixed gases are needed to simulate diverse gas compositions. These include hydrocarbon gases like methane, ethane, propane and small amounts of inert gases such as nitrogen and carbon dioxide. Adjusting gas ratios mimics gas from different regions. For calorific value analysis, precisely - formulated mixed gases let testers determine a gas's calorific value, a key metric for gas quality, pricing, and appliance design. In gas appliance R&D, testing mixed - gas calorific values helps engineers optimize combustion, improving appliance energy efficiency, reducing waste and pollution. A typical simulation mixed gas might be 90% methane, 5% ethane, 3% propane, 1% nitrogen, and 1% carbon dioxide.
4. Gas Alarms
Safety in industrial production and daily life is crucial, and mixed gases for gas alarms are essential for danger prevention. In industrial areas like coal mines and petrochemical workshops, where flammable, explosive, or toxic gases may exist, gas alarms are used for monitoring. Their calibration and testing rely on specialized mixed gases, which combine target gases (e.g., methane, carbon monoxide, hydrogen sulfide) with inert nitrogen in specific ratios. Regular calibration with these standard gases ensures alarms can accurately signal during operation, giving workers time to escape and respond to emergencies, preventing gas - leak - related disasters such as explosions and poisonings. For instance, in coal mining, methane is common. Calibrating methane alarms with a methane - containing mixed gas safeguards coal mine operations and miners' lives. A methane - based gas - alarm mixed gas may have 1% - 5% methane in nitrogen, based on the alarm's detection range.
5. Mixed Gases from Air Separation
Air separation technology isolates oxygen, nitrogen, argon from air. Mixed gases are prepared for various needs. In industrial production, many processes require oxygen - nitrogen mixes in different ratios. For example, in metal heat - treatment, controlling the oxygen - nitrogen ratio adjusts metal oxidation and decarburization, improving material and product quality. In electronics, high - purity air - separation mixed gases are used in semiconductor manufacturing. In chip manufacturing, a nitrogen - hydrogen mix is used for annealing to relieve internal stress. In food preservation, air - separation mixed gases modify packaging gas. A nitrogen - carbon dioxide mix in food bags inhibits oxidation and microbial growth. A metal - heat - treatment gas may have 20% - 50% oxygen, rest nitrogen. A chip - annealing gas usually has 80% nitrogen and 20% hydrogen.
6. Traffic Safety Detection
Traffic safety detection is vital for road safety, and mixed gases have a key role. In vehicle exhaust testing, special mixed gases are needed to calibrate equipment. These gases mimic vehicle exhaust components like carbon monoxide, dioxide, hydrocarbons, and nitrogen oxides. Regular calibration with standard mixed gases ensures accurate detection results. Precise exhaust detection helps traffic authorities spot high - emission vehicles. This prompts owners to do maintenance, reducing pollution and protecting public health. For instance, during annual vehicle inspections, using a mixed gas with set concentrations of key pollutants calibrates instruments, ensuring data accuracy and controlling emissions for better urban air quality. A typical calibration mixed gas might have 1% - 5% carbon monoxide, 0.1% - 1% hydrocarbons, 0.05% - 0.5% nitrogen oxides, with the rest mostly carbon dioxide and nitrogen.
7. Motor Vehicle Exhaust Detection
With the continuous increase in the number of motor vehicles, exhaust pollution from these vehicles has emerged as a significant concern. Mixed gases for motor vehicle exhaust detection are of paramount importance as they accurately replicate the intricate composition of motor vehicle exhaust. This composition encompasses carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, as well as minute quantities of particulate matter precursors.
During the exhaust detection process, the equipment makes a comparison between the detected exhaust components and the standard mixed gas. For example, in the simple working condition method, the equipment measures the concentrations of exhaust components in real - time under simulated driving scenarios and then contrasts these values with the pre - set standards. If the measured values exceed the standards, the vehicle requires maintenance and adjustment.
This accurate detection approach, which depends on standard mixed gases, provides robust support for curbing motor vehicle exhaust pollution and enhancing urban air quality. A comprehensive motor vehicle exhaust - detection mixed gas may additionally contain trace amounts of sulfur dioxide, typically in the range of 0.001% - 0.01%, along with gases related to particulate matter.
8. Environmental Monitoring
Environmental monitoring is key to global ecological protection, with mixed gases playing an important role.
In atmospheric monitoring, mixed gases are used to calibrate instruments for measuring pollutants like sulfur dioxide, nitrogen oxides, and particulate matter. Accurate preparation of these gases ensures data accuracy and comparability, allowing environmental agencies to assess air quality and formulate policies.
In water quality monitoring, mixed gases are also applied. For example, a standard mixed gas with known dissolved oxygen concentration calibrates dissolved oxygen meters. Precise dissolved oxygen measurement is vital for evaluating water self - purification, pollution levels, and aquatic ecosystem health.
An atmospheric sulfur - dioxide - calibration mixed gas may have 0.1 ppm - 10 ppm sulfur dioxide in nitrogen. The water - quality - monitoring dissolved - oxygen - calibration mixed gas contains precisely adjusted dissolved oxygen in an inert - gas - based solution.
9. Calibrating Instrumentation in the Fertilizer Industry
The fertilizer industry is crucial for agriculture, and instrumentation is vital for precise production control. Specialized calibration mixed gases are needed for accurate instrument measurements. In ammonia synthesis during fertilizer production, strict control of the hydrogen, nitrogen, and ammonia ratio is essential. Calibration gases are prepared according to actual gas composition and concentration ranges. Regular calibration ensures long - term instrument accuracy. Precise readings allow operators to adjust production parameters, optimize the process, boost efficiency, cut costs, and maintain product quality, providing high - quality fertilizers for agriculture. An ammonia - production calibration mixed gas may have 70% hydrogen, 25% nitrogen, and 5% ammonia.
10. Iron and Steel Industry
The iron and steel industry, a key part of the national economy, uses mixed gases widely in production.
In steel smelting, especially in converter steelmaking, high - purity oxygen in oxygen - nitrogen mixed gases quickly oxidizes impurities in molten iron, improving steel quality. Nitrogen acts as a protective gas; in continuous casting, it forms a gas curtain on molten steel to prevent oxidation and enhance billet quality.
During steel heat - treatment, like annealing, hydrogen - nitrogen mixed gases protect steel from oxidation, reducing surface oxides and improving surface finish and mechanical properties.
In gas analysis for steel production, standard mixed gases calibrate instruments, ensuring accurate furnace gas monitoring for production optimization.
Converter - steelmaking oxygen - nitrogen mixed gas usually has 95% - 99% oxygen and the rest nitrogen. Steel - annealing mixed gas typically contains 10% - 30% hydrogen and 70% - 90% nitrogen.
11. Power and Energy Sector
In the power and energy field, mixed gases have important applications. In high-voltage electrical equipment, sulfur hexafluoride (SF6) and nitrogen mixed gases serve as insulation and arc-extinguishing media. SF6 has great insulation and arc-extinguishing properties but is expensive and harmful to the environment. Mixing it with nitrogen in an appropriate ratio cuts costs and environmental risks while keeping equipment performance. For instance, in high-voltage circuit breakers, the mixed gas quickly extinguishes arcs during switching, protecting equipment and ensuring power system stability.
In emerging energy areas like fuel cell research and production, mixed gases are crucial. Proton-exchange-membrane fuel cells need a hydrogen-oxygen (or air) mixed gas as the reaction medium. Precise control of gas flow rate and ratio is vital for improving fuel cell power generation efficiency and stability. Optimizing the mixed-gas supply and reaction conditions enables fuel cells to convert chemical energy to electricity more efficiently, supporting future energy sustainability.
Typically, a high-voltage-equipment-insulating mixed gas has 10% - 30% SF6 and 70% - 90% nitrogen, while a fuel-cell-reaction mixed gas contains 90% - 99% hydrogen and 1% - 10% oxygen.
12.Common Mixed Gases in the Petrochemical Industry
The petrochemical field has diverse mixed gases with unique uses. Hydrogen - nitrogen blends are for hydrogenation and nitrogen - hydrogen for ammonia synthesis. Cracking gas, from high - temp pyrolysis of petroleum hydrocarbons, contains ethylene, propylene, butadiene, methane, ethane, propane, hydrogen, carbon monoxide, and carbon dioxide. It's separated to get high - value - added products. Reformate gas, from petroleum reforming, has hydrogen, methane, ethane, propane, and aromatic hydrocarbons, used in hydrogenation and for making plastics, etc. Desulfurization tail gas, from petroleum desulfurization, has hydrogen sulfide, sulfur dioxide, hydrogen, nitrogen, and trace hydrocarbons. It needs treatment for emissions and sulfur recovery. Cracking gas may have 30% - 50% ethylene, etc.; reformate gas, 40% - 60% hydrogen, etc.; and desulfurization tail gas, 1% - 5% hydrogen sulfide, etc.
Conclusion
The extensive applications of mixed gases across multiple sectors underscore their immense value and potential. As technology advances and industries evolve, the types and applications of mixed gases will continue to expand and deepen, playing an increasingly crucial role in driving human society forward.
