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What temp and pressure do super critical boilers work above?
**Efficiency increases with both temperature and pressure.
What are advantages of Super Critical Boiler?
- 1) High efficiency
- 2) Lower emissions
- 3) Lower cost
- i) Once through is simpler
- ii) No drum
- iii) Smaller diameter tubes
Give 3 reasons why CFB is better than PC for SCB?
- 1) For CFB highest heat flux region is in the water heating section.
- 2) For PC highest heat flux is near water-steam transition region.
- 3) Highest heat flux is much higher than average in PC.
- 4) Much more uniform heat distribution
In a gas turbine what happens to efficiency as pressure ratio increase?
It increases in a logarithmic fashion.
What two types of gasification are used for IGCC?
- 1) Air blown - 0.5 heating value of O2 blown
- 2) Oxygen blown - Much better for CO2 capture as flue gas is only CO2 and H2O
What are benefits of IGCC (4)?
- 1) Low emissions
- 2) High efficiency
- 3) Best for CO2 capture
- 4) Can produce H2
Give some barriers to IGCC deployment.
- 1) PC can meet current standards
- 2) IGCC financing costs are higher
- 3) No reward for risk taking
- 4) Bottle neck construction
- 5) More project planning
Rank types of gas turbine cycles by efficiency.
- Simple cycle (36.4%)
- Combined cycle (52.7%)
- Co generation cycle (85.1%)
- Combined cycle with Cogen (89.3%)
What are some ways to meet zero emission technology?
- 1) In-situ carbon capture (oxygen firing and chemical looping)
- 2) Gasification systems (e.g. IGGC)
What was the US zero emission project?
- Annouced by bush in 2003
- in 2007 Mattoon Township
- in 2009 funding was pulled
What are some benefits for vertical axle wind turbines?
- 1) Independent of wind direction
- 2) Low rotational speed (Torque up, Power down)
- 3) Mechanical components are on ground level for easy access.
- 4) Expensive tower is not required.
What is the betz limit?
- Theoretical maximum efficiency
What is the ideal tip speed ratio for 2 and 4 blades?
**Efficiency increase with number of blades but noise increase with tip speed ^5
What are the components of the wind turbine?
- Hub height - Height to middle of props
- Gearbox and generator - Found in hub
- Swept blade area
What are general cut in and out speeds?
- Cut in 7-10mph
- Cut out 45-80mph
- Rate speed 25-35mph (where design power is found)
What are the parts of a hydro turbine?
- 1) Spillway - Release water downstream that is not used to make energy
- 2) Penstock - Collects water from upstream leading it to turbine
- 3) Draft tube - Passage directly below turbine
- 4) Tailrace - Passage from draft tube downstream
- 5) Surge tank - Reservoir that vents sudden pressure build up if required.
- 6) Intake - Leads to the penstock
- 7) Reservoir - Upstream water source
What are the types of turbines?
- 1) Reaction (Static pressure changes)
- Converts both flow and kinetic energy
- Axial flow - Kaplan
- Radial or mixed flow - Francis
- 2) Impulse (Static pressure is constant)
- Converts only kinetic energy
- Tangental bucket flow - Pelton
What is Kaplan used for?
- 1) Very low head
- 2) High volume flow
For differnt turbines what are the specific speeds (non-dimensional)?
- Axial Flow 7-14
- Mixed flow (Francis) 3.5-7
- Centrifugal or radial flow (Francis) 1-3.5
- Impulse (Pelton) 0-1
Random facts about micro-hydro.
- 1) Typically produce up to 100kw power
- 2) 2000MW installed in Canada
- 3) 40 in NS supplying 11% of provincial capacity
What are the things that must be taken into account in LCA?
Material extraction, Material Production, Product manufacture, Distribution, Retail, Use, Disposal
**There is also transportation throughout
What are the steps of LCA?
- 1) Goal and scope definition
- 2) Inventory analysis
- 3) Impact assessment
What are the applications of LCA for companies?
- 1) Product development and improvement. (Product comparison)
- 2) Strategic planning (Product assessment)
- 3) Public policy making
- 4) Marketing (Eco-Labeling)
What are the applications of LCA for comsumers?
- 1) Product comparison
- 2) Product assement
- 3) Eco-labeling
What are some global warming potentials?
- CH4 - 25
- N2O - 298
- HFC - 124-12800
- PFC 7000-12000
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