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 ).
Get link
Facebook
X
Pinterest
Email
Other Apps
Boiler Safety and Test
Get link
Facebook
X
Pinterest
Email
Other Apps
-
Boiler Hydro Test
Boiler hydro test is used to ensure all the welding joints, pipe bents and all headers are water leak proof.
It is done at pressure of 1.5 times of design pressure.
E.g.: If design pressure of boiler is 50 bar, then the hydraulic test pressure will be 75 bar.
Pre-Checklist Hydro Test
Following are the pre-checklist for the hydro test of Boiler:
All erection work should be completed.
Confirm that no foreign material left in the boiler.
Confirm the drum manhole is closed with proper gasket.
Confirm all the drain system ready for operation.
All safety valve should be gagged.
The range of the pressure should be 2 times of the maximum test pressure but not less than test pressure.
The pressure gage should be pre-calibrated before test.
The test pump should have capacity of more than test pressure.
Minimum quantity of demineralized water should be available equivalent to the boiler capacity.
Ensure condensate and Feedwater chemistry parameters to strictly adhere to the required standard.
PH value should be in range of 8 - 9.
The water temperature should not less than 21.1 ℃.
Isolate all pressure and temperature gages except some pressure gages for hydraulic pressure measurements.
Start the boiler filling with the filling pump through the drain header (or filling time).
Close all vents sequentially after water coming from the vents.
Start the hydro test pump ensure all vents closed and rise pressure gradually to the design pressure and then the pressure to be raised up to the test pressure. E.g.: Design pressure = 200 bar, Test pressure = 300 bar).
Hold the pressure raising at 50 bar and 100 bar to check any valve passing and inspect leakage in pressure parts.
Once the pressure reached to the test pressure stop pressurizing and observe pressure drop if the pressure drop is very less then the test is successful.
If any defect is found, type of defect should be solved.
If the pressure is holding better then the pressurizes at 50 bar by opening top vents.
After this, checking team is ready is to inspect inside boiler physically.
After safety test, documents to be prepared and signed with the concerned authorities.
Projection: The term Projection is defined as: Presentation of an image or an object on a surface. The principles used to graphically represent 3-D objects and structures on 2-D media and it based on two variables: Line of Sight. Plane of Projection. Line of Sight & Plane of Projection: Line of sight is divided into 2 types: Parallel Projection Converging Projection & A plane of projection is an imaginary flat plane upon which the image created by the lines of sight is projected. Orthographic Projection: When the projectors are parallel to each other and perpendicular to the plane of projection. The lines pf sight of the observer create a view on the screen. The screen is referred to as the Plane of Projection (POP). The lines of sight are called Projection lines or projectors. Rules of Orthographic Projection: Edges that are parallel to a plane of projection appear as lines. Edges that are incl...
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Flywheel It is defined as, " a machine element which serves as reservoir which stores energy during the period when energy supply is more than the requirement and releases it when energy is less than requirement " . Used in IC, reciprocating (compressors or pumps) engines, presses, etc. Excess energy is stored in flywheel and release to crankshaft during other strokes in which no energy is developed. If space is small ↠ use small diameter and solid flywheel . If space is not limited (like for presses, crushing machine, hammering machine) ↠ use large diameter and hollow flywheel . Purpose of flywheel is to: reduce amplitude of speed fluctuation (sinusoidal) for constant power output. reduce maximum torque required. energy stored and release when needed during cycle. Parts of flywheel are Rim ↠ outer portion of flywheel (which is like a wheel). Hub ↠ center part which is installed on shaft. Arms or Needle ↠ rods joining rim to ...
Comments
Post a Comment
HI, we wI'll contact you later