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?
2 blades (5)
4 blades (3)
**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
What are some global warming potentials?
CH4 - 25
N2O - 298
HFC - 124-12800