Below what carbon content does bituminous coal lose its caking characteristics_______________?
Show answer Hide answer
Answer: A. 78-81%
Explanation
Bituminous coal undergoes carbonization and softening when heated, a property known as caking. Coals with volatile matter and carbon percentages falling into specific ranges lose this softening behavior. Empirical coal classification shows that caking characteristics disappear when carbon content drops to seventy eight percent. Coal rank is determined by the degree of transformation from vegetable matter to anthracite over geological time. Caking coals are essential for producing metallurgical coke used in blast furnace ironmaking. Proximate analysis measures moisture, volatile matter, fixed carbon, and ash content in coal.
Steel mills must select caking coals carefully to ensure high-quality coke production for blast furnaces. Power plants burn various coal ranks based on heating value and emission characteristics rather than caking. Coal classification standards guide industrial purchasing and combustion equipment design. Option B represents higher rank coking coals that retain strong caking and softening properties. Option C designates high-carbon bituminous coals that readily form strong metallurgical coke. Options D and E describe semi-anthracite and anthracite coals which lack bituminous caking behavior.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Typically, how much coal is consumed per kWh generated in a standard thermal power plant__________________?
Show answer Hide answer
Answer: C. 0.6 to 0.8 kg
Standard coal-fired thermal power plants typically consume around zero point six to zero point eight kilograms of coal per kilowatt-hour. Thermodynamic losses in boilers, steam turbines, and electrical generators dictate...
Q2. What is the typical compression ratio range for standard passenger car engines___________________?
Show answer Hide answer
Answer: B. 7
The compression ratio of an internal combustion engine compares cylinder volume at bottom dead center to top dead center. Standard passenger car gasoline engines are designed with compression ratios ranging typically bet...
Q3. What is the maximum allowable ash content percentage in diesel oil_______________?
Show answer Hide answer
Answer: E. 0.001%
Diesel fuel specifications restrict ash content to extremely low levels, typically a maximum of 0.001%, to prevent fuel system wear. Excessive ash-forming mineral compounds in diesel oil can cause abrasive wear on precis...
Q4. How does compressor volumetric capacity change when suction temperature drops_________________?
Show answer Hide answer
Answer: A. increases
When suction temperature drops, incoming refrigerant gas density increases, which enhances mass flow rate and volumetric capacity. Higher gas density means each stroke of the compressor pumps a greater mass of refrigeran...
Q5. What is the physical condition of steam inside a boiler drum___________________?
Show answer Hide answer
Answer: B. wet
Inside an operating boiler drum, boiling water and generated steam coexist in continuous thermal equilibrium at saturation temperature. The steam leaving the boiling water surface carries entrained moisture droplets, mak...
Q6. What does the critical path in a project network signify_______________________?
Show answer Hide answer
Answer: A. the minimum time required for completion of project
The critical path in a project network represents the longest sequence of dependent tasks, determining the minimum total time required to complete the project. Any delay in completing tasks along this critical sequence d...