Process Systems and Applications - Principles of Flow Measurement and Process control

Assignment: Counter-gravity Slurry Flow Measurement and Auto-control System

The objectives of the project are to create a solid mass flow rate measurement and automatic volumetric flow rate control system in the inclinable slurry flow test bed in G56 laboratory (Figure 1). The project is to use the existing electromagnetic flow meter (EMF), add one flow density meter (FDM, based on differential pressure measurement) to the vertical section of and one hydraulic automatic slurry control valve (ACV) to the existing flow test bed in G56. One appropriate automatic control strategy (in single loop feedback control) will be applied to achieve the required precision less than ±1% of maximum slurry flow rate.

The EMF will measure the volumetric flow rate of the slurry. The FDM will give the density of flow mixture and the ACV will execute the control of the slurry flow in the automatic control system (ACS). It is known the internal diameter of the pipeline is 0.05 m; the required range-ability of slurry volumetric flow measurement is from 0.196x10^-3 m³s^-1 to 7.85x10^-3 m³s^-1 in regard to flow velocity from 0.1 ms^-1 to 4.0 ms^-1 and the demanded maximum controllable slurry flow rate is 2.5x10^-3 m³s^-1 with turn-down ratio at 10. The slurry feed-in is treated as a wild flow with the solid concentration up to 20%, specific density 2.4 and size distribution from 50 to 400 μm. The internal energy conversion and the slip velocity between two phases (solid and water) are assumed ignorable.

Your contributions would be appreciated, which should focus on,

a) Decide the installation distance between two DP sensing points and calculate the differentia pressure measurement range to handling the slurry flow.

b) Select one electromagnetic flow meter (EMF) from suppliers on the website for the project.

c) Select one slurry automatic control valve (AVC) from suppliers on the website for the project.

d) Draw a physical layout of the flow control system.

e) Identify manipulated and controlled variables, also possible disturbances.

f) Select appropriate control strategy.

g) Draw a block diagram with text definition to reflect your strategy.

h) Derive the transfer function of the control system.

References: Faraj Y (2014) Mathematical Modelling of Flow Density Metering, Research Report of IAA project, University of Leeds

Faraj Y and Wang M (2012) ERT investigation on horizontal and vertical counter-gravity slurry flow in pipelines, Procedia Engineering, Elsevier, 42, 588 - 606.