Wednesday, March 10, 2010

Know about Humidity

Know about humidity and its significance.

http://www.esnips.com/doc/9111fcb1-d2f5-4454-b1ac-27f734dc7ea5/humidity

Monday, March 8, 2010

Horizontal Cylinderical Tanks

Tanks are used for the storage fluids in many chemical process industries. For a horizontal cylinderical tank, the two ends (heads) of the vessels is usually both flat, dished, elliptical or hemispherical. It is commonly required to estimate the quantity of fluid in a tank when it is partly filled with fluid, and only fluid level is known. This partial volume is made up of the volume in the cylinderical shell plus the volumes in the two heads. The partial volumes can be estimated by the equations below:
Partial volume of horizontal cylinder:
    = {r2cos-1[(r - h)/r] - (r - h)(2rh - h2)0.5}L
Partial volume of dished heads:
    = 0.215483*h2(1.5d - h)
Partial volume of elliptical heads:
    = 0.5236*h2(1.5d - h)
Partial volume of hemispherical heads:
    = 1.0472*h2(1.5d - h)

where
     L = side length of the cylinder shell
     d = internal diameter of the cylinder
     r = radius of the cylinder = d/2
     h = height of liquid in the cylinder
All volume equations give fluid volumes in cubic units from tank dimensions in consistent linear units.

Sizing Of Orifice For Liquid Flow

The orifice meter is a device for measuring the rate of flow of liquid and gas through a pipe. Typically, it consists of a flat circular plate which has a circular sharp-edged hole called orifice, which is concentric with the pipe. In chemical process design, an orifice is usually sized for known flowrate and presure drop. For liquid flow, the commonly applied equations are:

     
where
     d = orifice diameter, inch
     CD = maximum allowable vapor velocity ≈ 0.62
     D = pipe inner diameter, inch
     Δp = pressure differential, psia
     W = full-scale upstream mass flow rate, lb/s
     ρ= upstream liquid density, lb/ft3