Pre Midterm Flashcards
Advantages of Fossil Fuels?
- Relatively plentiful
- Low cost
- Convenience to use
- High energy contents
4 most desirable properties for a fuel are
- High energy density
- Good combustion characteristics
- Low toxicity and exhaust emissions
- Requiring easy and inexpensive refining processes
What is the difference between a reserve and a resource?
- Resource
- Don’t know the exact location, quality, and quantity
- Reserve
- Known quality and quantity of the resource
What distinguishes a proved, probable, and possible reserve?
- Proved reserve: at least 90% certainty
- Probable: 50%
- Possible: 10%
Name alternative energy sources other than fossil fuels
- Solar
- Nuclear
- Wind
- Tidal
- Geothermal
- Biomass
- Hydroelectric
The origin of all energies comes from?
The sun
Where does coal come from and what are its by products?
- Coal consists mainly of carbonized plant matter, found mainly in underground deposits
- By products: O2, ATP, heat
Two types of IC engines and examples of each
- Steady
- Gas Turbines
- Aviation
- Power Plant
- Fuel Cell
- Gas Turbines
- Intermittent
- Reciprocating
- CI
- SI
- Rotary
- Reciprocating
What is a stratified charge engine?
Internal combustion engine, in which the fuel is injected into the cylinder just before ignition. Ignition takes place at the richest area
What does wood consist of?
- 40-50% C
- 6% H
- 35% O
- Other compounds
6 steps in burning solid fuels
- Preheating
- Volatile Evap
- Ignition
- Smouldering (flameless burning)
- Flaming
- Extinguishing
Define Pyrolysis
Thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen
Define Smouldering
Slow, low temperature flame form of combustion
What is Charcoal?
When wood is heated up to 270C, the volatile fractions start to evaporate and we get a black substance called charcoal (70% carbon)
How is Activated Charcoal formed?
If charcoal is treated with NaOH and heated to 600C at the presence of Ar and N2 then activated charcoal is formed
1 gram covers 3000 m^2 of surface
3 applications of activated charcoal
- Fuel storage
- Filter
- Purifier
What is Peat?
A brown, soil-like material characteristic of boggy, acid ground, consisting of partly decomposed vegetable matter.
What is the coalification process?
Coalification is the process of the chemical transformation from vegetation into coal as a result of temperature, pressure, and time
Wood → Peat → Coal
Carbon content increases →
Oxygen decreases →
What are the two types of coal analysis?
- Proximate
- Ash, moisture, volatile matter, carbon
- Ultimate
- CHONS and Ash
How does sulfuric acid and nitric acid form from the combustion products?
SO2 and NO2 in the presence of moisture can turn to sulfuric acid and nitric acid. This is damaging to chimneys and pipes.
What are the 3 main types of coal and there respective carbon content %?
- Lignite
- Brown Coal
- 65-70%
- Smoky Flame
- Bituminous
- Coke/Not Coke
- Yellowish
- Smells like tar
- Anthracite
- Bright black
- 90-95%
- No smoke
What is considered good and low quality coal in terms of ash content?
- Low ash coal < 4% ash
- High ash coal > 8% ash
How does a higher silicon dioxide content affect ash?
Higher silicon dioxide, higher melting temperature desirable in steel mills
Procedure for ash melting temp?
Start at 1000°C → Deformation Method → Softening Temp → Fluid Temp
What does coal grade consist of?
- Fixed carbon %
- HV
- Sample Size
- Ash Melting Temp
- Ash Content
- Ash Softening Temp
- Sulfur Content
What are the two types of coal mines?
- In-Situ
- Original bed
- Drifted
- Broken due to ground seperation
- Contaminated and deformed
How does an Orsat Apparatus work?
Measures oxygen, carbon monoxide and carbon dioxide content. The amount of N2 is equal to total volume. After leveling the liquid in the bottle and burette, the remaining volume of gas in the burette indicates the percentage absorbed.
What are the 3 coal processes?
- Coal hydrogenation (liquid fuels)
- Coal carbonization (solid fuels/coke)
- Coal gasification (gaseous fuels)
What is coal hydrogenation and its properties (T, P)? Name two methods
- At a high T and P, hydrogen is fed to coal in the presence of a catalyst (Co, Ni, Pd, Pt)
- T = 450 to 480°C
- P = 200 atm
- Two Methods
- Bergius
- Fisher Tropsch
What are the two steps in the Fischer Tropsh method?
- Producing syngas (CO & H2)
- Steam reforming to produce H2
- Syngas + H2 → HC (light base)
What is coal carbonization?
Dry, no air process (destructive distillation)
- Heating the compound → different new simple componds produced
In coal carbonization, what are the four yields at a temperature range of 480-550°C
- Benzole
- Distillation gases (CH4, CO, CO2, H2O)
- Coal Tar (black residue consist of heavy HC)
- NH3, H2S, HCN
At what temperature range is coke typically formed in the coal carbonization process?
- Higher T = 1000-1100°C
- Also forms phenol and napthalene
Name examples of ranks that can produce coke
- Bitumunous
- Peat
- Carbon Content: 70-80%
What is the carbon % of coke? HV?
- Coke contains 92-93% C
- HV = 29 MJ/kg
What are the 3 advantages of coke?
- Constant known carbon content
- Coke is stronger than coal
- Less losses in transportation
- Very precious by-products (HCs)
Two methods to produce gaseous fuels from coal?
- Converters (water gas)
- Underground
What is the sequence to produce water gas?
Heating → Drying → Pyrolysis → Polymerization
What is Briquette?
Coal dust and peat is mixed with tar (7-8%) and compressed to get some blocks (bricks)
