View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
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Fluidized Bed Combustion Technology
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Fluidized Bed Combustion Technology
Fluidized bed combustion (FBC) is defined as, "a combustion technology used to burn solid or low grade fuels".
Fuel particles are suspended in a hot bed of particulate materials (like ash, sand, limestone).
Since this allows coal plants to burn at cooler temperatures, less NOx is also emitted.
We have large coal reservoirs but it has high Sulphur content ↣ to deal with this issue, we have Fluidized Bed Combustion Technology.
This technology is used because:
Sulphur emission decreases by Lime.
NOx emission decreases by decrease in temperature.
Circulating Type Fluidized Bed Boiler
It is defined as, "a boiler which works on the fluidized bed combustion technology for producing heat". There are two types of Circulating Type Fluidized Bed (CFB) Boiler:
Circulating Type ↣ Particle velocity ranges between 5 - 10 m/s.
Bubbling Type ↣ Particle velocity ranges between 1 - 3 m/s.
Construction
Bed Drain Tube ↣ used to remove ash.
Grid Plate ↣ where combustion occurs.
Submerged Tube Bank ↣ for producing steam.
Plenum Chamber ↣ used for storing air.
Working
Air from fan enters furnace↣ pass through bed of finely divided particles (sand) ↣ air velocity increases, sand particles vibrate (which heat air)↣ desired fuel is added (first secondary then primary fuel is added) ↣ when self sustained temperature of coal is added, we cut primary fuel ↣ then coal is added ↣ initial combustion starts ↣ unburned coal particles leaves furnace ↣ Primary cyclone capturing then back into furnace.
Loop Seals ↣ maintains the pressure balance between the furnace and exit of the separators allowing the solid to flow back into the furnace.
High Performance particle steam heat exchanger ↣ Interax which extracts high temperature heat from hot particles in CFB to produce high temperature superheated steam.
Ques: What does fluidized means?
Ans: When air (or gas) is passed through finely divided bed of solid particles (sand), the particle remain undisturbed at low velocity. As velocity increase, particles start to vibrate remain suspended in air stream.
Fluidized combustion ↣ (840 - 950)℃ much lower than ash fusion temperature, ash and NOx reduces.
Ash can be used as Cement Raw Material.
Advantages
Very low quality fuel is used. Like coal, biomass, tyres).
Coal is used in coarse phase (not in powdered form).
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Intersection Of Solids: Solids are obtained by the combination of of two or more basic solids. When two or more solids combine, a definite curve/line is seen at their intersection. This curve/line is called curve/line of intersection (COI / LOI) and it is the result of inter-penetration of solids. Applications Of Intersection Of Solids: Designing a sheet metal objects. Automobile Parts. Moulding patterns. Forged end of connecting road. Intersection of two contacting surface, etc. Inter-Penetration Of Solids: When one solids penetrates another solids then their surfaces intersect and at the junction of intersection a typical curve is formed, which remains common to both solids. This curve is called Curve of Intersection and it is a result of inter-penetration of solids. Cases Of Intersection Of Solids: First we need to discuss the general solution steps of how we draw intersection of solids diagram. So know, we are going to discuss the basic steps:...
Types Of Lines And Its Uses: There are three types of types on the basis of thickness and they are: Visible Lines ↝ It represents features that can be seen in the current view. Hidden Lines ↝ It represents features that cannot be seen in the current view. Center Line ↝ It represents symmetry, path of motion, centers of circles,, axis of asymmetrical parts. Dimension and Extension Lines ↝ It indicates the sizes and location of features on a drawing. Placement Of Dimension Lines: Dimension should be outside the view. Dimension should be applied to one view. Dimension should be placed in a view that shows the distance in its true length. Dimension lines should be placed, in general 10 mm (1/2 in) away from the outlines from the view. Parallel lines should be placed uniformly. Values should be midway (auto centered) between the arrow heads, except when a center-line interferes. Dime...
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