FM 301 PART A: Flow of Solids Through Bins

PART B: Pneumatic Conveying

Group A8/A: Rishikesh Awale 10D020009

Subahsh Chand Meena 100020028

Saurabh Suman 100020064 Durga Prasad Meena 100020025

PART A: Flow of Solids Through Bins MOTIVATIONSeveral Chemical Processes require transport

of powder form materials

Major examples are cement and pharmaceutical industry

The transportation of the powders is affected by various parameters which we want to study.

To study the effect of the powder level above the exit on the mass flow rate.

To study the effect of particle diameter and orifice diameter on the mass flow rate.

AIM

THEORYParticulate solids bear resemblance to both

solids and liquidsLiquids

Take shape of containerFlow through orificesExert normal pressure on container walls

SolidsShear stress is proportional to the normal loadCan sustain a shear stress

THEORYThe discharge rate depends on the orifice

diameter, particle density and acceleration due to gravity.

Two correlations based on Dimensional AnalysisIgnoring particle diameter effect

Beverloo’s Correlation

PROCEDUREFix an orifice plate at the bottom of the bin Fill the bin with the sand up to height ‘h’

keeping the exit closed. Open the exit and start the stop-watch at the

same time. Record the time required to empty the bin Accurately weigh the sand thus collectedRepeat the experiment for different sand levels

and then for different orifice platesRedo the steps for different particulate size.

OBSERVATIONS

OBSERVATIONS

RESULTS

DISCUSSIONS

SOURCES OF ERROR AND PRECAUTIONS• The stop watch should be started simultaneously as the

cork is removed.

• The sand level in the bin should be maintained at the given mark.

• Care should be taken that the sand does not fall out of the container.

• The orifice should be placed such that it is inclining downwards like the inner side of a funnel

• While changing the sand it should be seen that there is no amount of sand, with different particle size left over.

PART B: Pneumatic Conveying MOTIVATIONPneumatic Conveying refers to the moving of

solids suspended in or forced by a gas stream through horizontal and/or vertical pipes.

Pneumatic conveyors are compact and require less maintenance than conveyor belts and other transportation systems.

Major industrial applications include cement plants and food grains industry.

To study qualitatively the different flow regimes for different gas and solids flow rate for horizontal pneumatic conveying.

To measure pressure drops for gas-solid flow for different gas and solids flow rates.

AIM

THEORY Dilute phase transport

When the gas volume flow rates are much higher that that of the solids, the transport of solids is said to be in the dilute phase. In this case there is a nearly uniform distribution of solids across the pipe cross-section of the pipe and along its axis

Dense phase transport When the gas volume flow rates are much higher

that that of the solids, the transport of solids is said to be in the dilute phase. In this case there is a nearly uniform distribution of solids across the pipe cross-section of the pipe and along its axis

FORMULAEDilute Phase Regime

Dense Phase Regime

where ρ = density, u = velocity,∞ = volume fraction of gas in the pipe and the subscripts f and p refer to fluid and particle respectively,L is the length of the pipe, and m = Gp /Gf is the ratio of solid to gas mass flow rates, Cds is the drag coefficient for a single particle moving through the fluid at a velocity (uf – up).

PROCEDURE Adjust the air flow rate to a high value using the

rotameter. Open the solids flow valve to allow for flow rate of

the particles. Keep the solids flow rate constant throughout the experiment.

After steady state is reached, measure the mass flow rate of solids by collecting the solids in the beaker for a fixed time interval.

Make qualitative observations of the flow patterns. Note down the pressure drop in the manometer.

Decrease the air flow rate and repeat the steps (3-4). Note the particle diameter and density.

OBSERVATIONS

OBSERVATIONS

DISCUSSION

DISCUSSION

SOURCES OF ERROR AND PRECAUTIONSThe readings should only be taken once steady state

is achieved and the pressure difference becomes constant.

Collection of sand and starting of stop watch should be simultaneous and the actual time should be considered while doing the calculations.

The stopping of stop watch and the removal of mug should also be simultaneous.

The hopper should be continuously refilled with sand.