Enhancing Efficiency in Dolomite/CaCO3 Conveying for Paint Manufacturers

Industry:
Paint
Location:
Andhra Pradesh,India
Problem Statement –
  • The customer faced significant operational issues with their Dolomite/Calcium Carbonate pneumatic conveying system, resulting in decreased production efficiency and a dusty work environment.

Challenges
Descriptive text


  • The 60 HP motor consistently took on excessive load, leading to frequent tripping.
  • The line choked monthly, causing material to settle and block the system.
  • Material leakage occurred at flanges.
  • Rotary Airlock Valve tripped above 30% load.
  • Irregular hopper geometry resulted in poor flowability, leading to material bridging and rat-hole formation.
  • Butterfly Valves in the conveying line malfunctioned.
  • Material entered the airline due to back pressure from the Y-piece before the loading tee and lack of an isolation valve.
  • The system achieved a conveying capacity of less than 20 TPH, falling short of the required 30 TPH.
Data Collected & Data Analysis

Based on the data collected during our site visit, we did the data analysis & following results were obtained-

Description Units
Site conditions
Elevation above sea level 100.00 m
Minimum Temperature 16.00 °C
Maximum Temperature 45.00 °C
Materials
Name Dolomite/CaCO3
True Density 1450 kg/m3
Mean Particle Size 52 µm
Temperature 45.00 °C
Material Calibrating Factor 1.00
Gas
Name Air
Temperature 70.00 °F
Calculations
Capacity 8.33 kg/s
Gas Flow Rate 0.85 m3/s
Temperature Gradient 0.00 °C/100m
Equilibrium Temperature 45.55 °C
Pick-Up Velocity 18.33 m/s
Terminal Velocity 26.45 m/s
Discharge Pressure 0.00 kPag
Conveying Design Pressure 45.22 kPag
Material to Gas Ratio 8.16 to 1
Saltation velocity
Selected Saltation Velocity 10.33 m/s
Max Velocity for Dense Mode 8.26 m/s
Min Velocity for Dilute Mode 12.40 m/s
Map 1 Map 1 Map 1 Map 1
Root Cause Analysis

Our team conducted a detailed investigation to pinpoint the issues hampering the performance of the customer's pneumatic conveying system. Here's what we uncovered -

Sr. No. Problem Root Cause Analysis
1. Roots Blower Motor Tripping The existing blower lacked sufficient pressure and motor power to handle the required material conveying capacity.
2. Recurring Line Choking 1. Insufficient air pressure and volume caused material to settle, making it difficult to stay in suspension.
2. The RAV connection lacked a leakproof seal, allowing air leakage and reducing effective air supply.
3. Short-radius bends and elbows in the line caused pressure drops and powder accumulation at bends.
4. The Y-piece near the blower further reduced air pressure, worsening the flow issues.
3. Material Leakage at Flanges Substandard gaskets caused flange leaks and material loss.
4. Rotary Airlock Valve tripping above 30% Load Frequent line choking at the loading tee caused material buildup, overburdening the RAV and triggering shutdowns.
5. Poor Flowability in Charge Hoppers Moisture in the conveying air caused powder caking, while the hopper's irregular design aggravated material bridging and flow blockages.
6. Butterfly Valve Failures The valves were prone to leakage by design, causing powder to escape and rendering them ineffective over time.
7. Material Entering the Airline Back pressure from line blockages, combined with the absence of an isolation valve after the NRV, pushed material into the airline.
8. Underperformance of Conveying Capacity A combination of insufficient air, frequent line blockages, leaks, and poor material flow reduced capacity to under 20 TPH instead of the required 30 TPH.
Solution

Below modifications were suggested by us to mitigate the problems- -

Problem Statement Recommendations
Roots Blower motor tripping frequently Roots Blower specifications should be as below:
1. Capacity: 3061 m3/Hr.
2. Pressure: 0.7 Bar
3. Motor: 120 HP (VFD suitable)
Conveying line choking & RAV tripping above 30% load 1. Knife Gate Valves should be installed above (BFV) & below RAV to ensure leak-free operation.
2. The elbows/short radius bends used in the line should be replaced by long radius bends (min. 5D bends) to reduce the pressure drop & powder accumulation.
Material leakage at flanges Replace gaskets with Black Neoprene Rubber for leak prevention.
Poor material flowability in Charge Hoppers Install Pneumatic Vibrators to improve material flow and prevent bridging.
Malfunctioning Butterfly Valves Replace Butterfly Valves with Knife Gate/Dome Valves for better sealing and performance.
Material entering the airline due to back pressure Install a Butterfly Valve after the NRV to replace the ‘Y’ piece and stop material from entering the airline.
How we made a difference
  • We provided tailored solutions including equipment upgrades, installation instructions, and RIECO-make Knife gate valves, gaskets, and bends.
  • Reduced material leakage, leading to a dust free work environment.
  • Increased production efficiency and reduced downtime.
  • This resulted in a conveying capacity improvement to 30 TPH.


Results: The system now operates efficiently, consistently achieving the required conveying rate without issues.

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