Table of Contents
What are the different types of plume?
1) Looping Plume: Occurs in super adiabatic environment. Unstable and need higher stacks. 2) Neutral Plume: Upward vertical rise when ELR = ALR. 3) Coning Plume: When wind velocity is high and sub-adiabatic conditions exist (ELR < ALR).
What is a coning plume?
The coning plume occurs when there is roughly a neutral lapse rate from the surface well past plume height. Here the plume grows gradually both upward and downward, resulting in this cone shape. The last plume type is the fumigating plume.
What is plume shape?
Usually, as a plume moves away from its source, it widens because of entrainment of the surrounding fluid at its edges. Plume shapes can be influenced by flow in the ambient fluid (for example, if local wind blowing in the same direction as the plume results in a co-flowing jet).
What is fanning plume?
A pattern of smokestack plume dispersion in a statically stable atmosphere, in which the plume spreads out in the horizontal like an oriental fan and meanders about at a fixed height with little vertical spread.
How many types of plume behavior are there?
Six types of air pollution plumes illustrate the relationship between atmospheric stability and pollutant emissions: looping plumes, fanning plumes, coning plumes, lofting plumes, fumigating plumes, and trapping plumes.
What is adiabatic rate?
The adiabatic lapse rate is the rate at which the temperature of an air parcel changes in response to the compression or expansion associated with elevation change, under the assumption that the process is adiabatic, i.e., no heat exchange occurs between the given air parcel and its surroundings.
What is stack plume?
Plume: • The dispersion of emitted gases from the source of their production is known as plume and the source is known as stack.
What is a lofting plume?
Lofting is type of plume behaviour, which occurs when conditions are unstable above an inversion layer, the release of a plume is above the inversion layer. Actually lofting is considered to be one of the favourable situations for air pollutant dispersion.
What is neutral plume?
Neutral Plume : • Neutral plume occurs in neutral atmospheric conditions (ELR=ALR). Such type of plume rises vertically in an upward direction. • The upward lifting of the plume will continue till it reaches a height where density and temperature of surrounding air are equal to it.
What is thermal plume?
A plume is a substance which moves from a source into its surrounding area, such as a plume of smoke. A thermal plume is a plume that is specific to temperature alone.
When the plume is switched between the inversions the plume Behaviour is termed as?
Coning plume: it occurs when the atmosphere is nearly neutral and the velocity of wind is more than 32 km/hr. The plume thus formed takes the shape of a cone. Trapping Plume: As the name suggests, this type of plume is trapped in between the inversions and therefore it can diffuse vertically only to a certain height.
What is moist adiabatic rate?
The MALR (Moist Adiabatic Lapse Rate) is also called the wet or saturated adiabatic lapse rate. It is the temperature trajectory a parcel of saturated air takes. The wet adiabatic lapse rate varies from about 4 C/km to nearly 9.8 C/km. The slope of the wet adiabats depend on the moisture content of the air.
What is a looping plume?
Looping plume is of wavy character and occurs in super adiabatic environment (ELR>ALR), which produces highly unstable atmosphere because of rapid mixing. In an unstable atmosphere, rapid air movements take place vertically, both upward and downward and the plume becomes a looping plume.
What is plume and stack?
The dispersion of emitted gases from the source of their production is known as plume and the source is known as stack. The diffusion or dispersion of pollutants into the atmosphere is governed by the Environmental Lapse Rate (ELR) as well as Adiabatic Lapse rate (ALR), i.e., atmospheric temperature profile or atmospheric stability.
What is the difference between upward and downward mixing of plumes?
The upward mixing of plume is very rapid and turbulent, but downward mixing is less because the downward movement is prevented by inversion. The dispersion of pollutants therefore becomes rapid and pollutants cannot come down to the ground.
What is meant by trapping plume?
Such type of plume is therefore, termed as trapping plume. This plume is not ideal for dispersion of pollutants as it cannot go above a certain height. It is however, to be noted that plume rise depends not only on the stability of atmosphere, but also on the buoyancy and momentum of exhaust gases.