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Questions and Answers
What is the process of converting coal into a mixture of hydrogen and carbon monoxide called?
What is the process of converting coal into a mixture of hydrogen and carbon monoxide called?
- Coal liquefaction
- Combustion
- Electrolysis
- Gasification (correct)
High temperature materials are necessary for the gasifier to endure thermal shock and erosion.
High temperature materials are necessary for the gasifier to endure thermal shock and erosion.
True (A)
What is the temperature range for a gasifier chamber?
What is the temperature range for a gasifier chamber?
Between 1250 and 1550°C
The slag produced in gasification can exist in two forms: liquid slag that can flow out of the gasifier and ________ slag that solidifies on the refractory lining.
The slag produced in gasification can exist in two forms: liquid slag that can flow out of the gasifier and ________ slag that solidifies on the refractory lining.
Which of the following is a challenge of high chromium oxide refractory materials?
Which of the following is a challenge of high chromium oxide refractory materials?
Match the following materials with their properties:
Match the following materials with their properties:
What does CCS technology aim to achieve?
What does CCS technology aim to achieve?
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Study Notes
Steam and Gas Turbines
- Steam turbines and gas turbines are critical components in energy generation.
- Material design must consider high-temperature and high-pressure environments, influencing material selection and durability.
- Current materials face challenges such as thermal shock resistance, wear from particulates, and corrosion.
Advanced Power Generation Systems
- Advanced Ultra-Supercritical Combustion Systems (AUSC) operate at high temperatures and pressures, utilizing water as a supercritical fluid.
- Integrated Gasification Combined Cycle (IGCC) converts coal to synthetic gas (syngas) composed of hydrogen and carbon monoxide, optimizing fuel use.
- Fuel cells generate electricity through electrochemical reactions, notably achieving high efficiency in power generation.
- Carbon Capture and Storage (CCS) technology aids in reducing CO2 emissions from fossil fuel combustion by capturing and storing carbon underground.
Gasification Process
- Gasification transforms solid or liquid fuels (coal, petroleum) into syngas.
- Significant components of a gasifier include gasifier vessels, downstream coolers, and gas cleaning vessels.
- The gasifier chamber operates at temperatures between 1250°C and 1550°C and pressures of 3 MPa or higher.
Material Requirements in Gasifiers
- Materials used in gasifiers must withstand high temperatures, thermal shock, erosion from particulates and molten slag, corrosion, and variable oxidative/reductive conditions.
- Refractory materials protect the steel shell of gasifiers from erosion and corrosion under extreme conditions.
Refractory Compositions for Gasifiers
- Various refractory materials are utilized, including:
- Fuse-cast materials for chemical resistance but limited thermal shock resistance.
- Al₂O₃ and MgO/Al₂O₃ spinel materials with inadequate wear resistance.
- SiC and Si₃N₄ also show poor wear resistance.
- High chromium oxide (above 85 wt% Cr₂O₃) provides excellent chemical resistance and is preferred for severe wear areas, while lower chromium compositions suit less demanding environments.
- Effective performance in refractory materials generally requires a minimum of 75 wt% Cr₂O₃.
- Issues with high-chromium oxide refractory materials include high costs and the toxicity of hexavalent chromium (Cr⁶⁺).
- Future innovations may explore coatings, monolithic linings, and alternative low-chromium or chromium-free materials for improved safety and cost-effectiveness.
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