Performance Analysis Report: MEE Units

MEE Units Performance Analysis Report

Background & Report Objective

• Evaluates and compares the operational performance of MEE-2, MEE-3, and MEE-4 over their respective operating periods.

• The objective is to analyze performance trends and cleaning effectiveness for long-term operational reliability and optimization potential.

MEE-3 Plant (Revamped with TG-Klaren Self-cleaning Technology)

Plant Details

• Capacity: 72 KLD

• Service: Same effluent as MEE-2 (CaSO₄-rich chemical stream)

• Design: Conventional forced circulation MEE

• Tubes per Calandria: 62 nos

• Fouling Tendency: High

Summary of Cleaning Events

• Hydrojet Cleaning of Cal-1: February 6-8, 2025

• Nitric cleaning of Effect 2 to 4: February 27 - March 2, 2025

• Hydrojet Cleaning: March 11-31, 2025

Key Performance Metrics (January 29, 2025 to April 14, 2025 – 48 Operational Days)

Insights and Information from Plant Data (29 JAN 2025 TO 13 APR 2025)

• Before Hydrojet of Cal-1 (29 Jan to 5 Feb 2025)

  • Stable performance with high recovery around 73% and steam economy around 2.18.

  • Cal-1 was relatively clean, and self-cleaning performed effectively.

• After Hydrojet of Cal-1 & Before Nitric Cleaning (9 Feb to 26 Feb 2025)

  • Low vacuum observed despite VP draining and pump changeover.

  • Frequent choking in bottom tank suction/discharge lines reduced evaporation.

  • Resulted in recovery drop to 64% and moderate steam economy 2.01.

• After Nitric Cleaning of Effect 2 to 4 (3 Mar to 10 Mar 2025)

  • Stable but lower performance with recovery down to 59%.

  • Steam rate rose from 0.6 to 0.9 T/hr due to fouling in Cal-1, reducing heat transfer efficiency and increasing thermal resistance.

  • More steam was needed to maintain bottom temperatures, indicating resistance in the evaporation zone.

• Post-Hydrojet Cleaning (1 Apr to 14 Apr 2025)

  • After March 10, vacuum improved to around -500 to -530 mmHg, resulting in a recovery improvement to 76% as of April 13, 2025.

  • Initial operation faced low feed rates due to a high level in the top tank.

  • Particle movement delayed—caused by blockage in the booster suction line, later resolved.

  • From April 5 to April 9, vacuum dropped to -300 to -450 mmHg due to:

    • Dyke area waterlogged

    • Submerged drain valve

    • Resulted in reduced evaporation and system performance.

  • After April 10, vacuum improved to -500 to -530 mmHg, and recovery rose to 76% by April 14.

• Impact of Bottom setpoint temperature on Fouling:

  • During the phase before 2nd Hydrojet, RCP-1 discharge bottom temperature setpoint was kept at 99°C.

  • This led to high Cal-1 temperatures, accelerating very hard fouling in the tubes.

  • Post-cleaning, the following corrective measures were taken:

    • Bottom setpoint was reduced to 95°C.

    • RCP-1 frequency fixed at 44 Hz.

    • Result: Smoother recirculation, softer scaling, improved cleaning cycle lifespan, and more stable particle motion.

• Vacuum Issues from Graph analysis:

  • Inability to drain vacuum pump collection pot due to submerged drain valve (dyke flooding).

  • Persistent leakages in the vacuum system.

  • All these led to fluctuating and low vacuum performance until addressed post-10th Apr.

• System Stabilization & Overall Performance:

  • MEE-3 operated for 47 days with the Klaren system functional throughout.

  • Delivered an average recovery of 65% and steam economy of 2.02 over 1.5 months.

  • Best Performance aligned with:

    • Clean Cal-1 conditions.

    • Bottom temp set at 95°C.

    • Particle flow normalization.

    • Improved vacuum and drainage.

• Graphical Reference: Refer Fig 1 in Annexure

MEE-2 Plant

Plant Details

• Capacity: 72 KLD

• Service: Handles chemical effluent containing calcium sulphate

• Design: Conventional forced circulation MEE

• Tubes per Calandria: 162 nos (As mentioned by Aarti)

• Fouling Tendency: High

Summary of Cleaning Events

• Nitric Acid Cleaning: Conducted twice — around March 4-5, 2025 and March 13-16, 2025

• Hydrojet Cleaning: Conducted from March 19 to April 9.

Key Performance Metrics (January 29, 2025 to April 10, 2025 – 45 Operational Days)

Insights and Information from Plant Data (29 JAN 2025 TO 10 APR 2025)

• Pre-Nitric Cleaning (29 Feb to 3 Mar 2025)

  • Plant operation showed flat performance with low vapor generation.

  • Steam economy at avg. 1.45 and avg. recovery at 46.71%, pointing to scaling/fouling buildup.

• Post-Nitric Cleaning (6 Mar to 12 Mar 2025)

  • Top rate and recovery improved, but feed rate slightly dipped.

  • Steam economy declined to 1.23, possibly due to process realignment or increased vapor escape.

  • Cleaning effect was temporary, and benefits started declining within days.

• Post-Hydrojet Cleaning (19 Mar to 9 Apr 2025)

  • Major performance boost:

    • Feed rate ↑ to 47%

    • Recovery ↑ to 75.5%

    • Steam economy peaked at 1.66

  • Indicates restored heat transfer significantly reducing resistance.

• Recovery Spikes Based on Graph Analysis

  • During the "Post-Hydrojet" phase, recovery saw short-term spikes on 4 occasions each following:

    • Vacuum pump collection tank draining

    • Tank changeovers

  • These operational interventions temporarily reduced backpressure and improved vapor draw, enabling better evaporation and recovery.

• System Stabilization

  • Overall, MEE-2 ran more efficiently after Hydrojet cleaning, averaging 68% recovery over the recorded period of Feb–Mar 2025.

  • Suggests the importance of both mechanical cleaning and support system maintenance (e.g., vacuum efficiency).

• Graphical Reference: Refer Fig 2 in Annexure

MEE-4 Plant

Plant Details

• Capacity: 72 KLD

• Service: RO reject mixed with NT (nitration) stream

• Design: Tube layout and shell diameter same as MEE-3

• Tubes per Calandria: 62 nos

• Fouling Tendency: High

Summary of Cleaning Events

• 1st Nitric Cleaning: January 31 - February 1, 2025

• Vacuum Pump (VP) Maintenance work: February 11-12, 2025

• RCP-1 Maintenance work: From February 17-19, 2025

• Vacuum Pump (VP) Maintenance work: February 27-28, 2025

• Hydrojet Cleaning: Conducted from March 4-10, 2025

• 2nd Nitric Cleaning: From April 3 onwards

Key Performance Metrics (January 29, 2025 to April 2, 2025 – 50 Operational Days)

Insights and Information from Plant Data (29TH JAN 2025 TO 02nd APR 2025)

• Before 1st Nitric Cleaning (29–30 Jan 2025):

  • Very short period but with good steam economy 2.83, possibly due to cleaner initial conditions.

  • Recovery was low 51% as plant was just stabilizing.

• Before Hydrojet Cleaning (2 Feb to 3 Mar 2025)

  • Reasonable feed rate of 2.07 m³/hr with moderate steam rate of 0.69 T/hr.

  • Recovery improved to 65.84%.

  • Drop in steam economy 1.99 indicates early signs of fouling impacting heat transfer.

• After Hydrojet Cleaning & Before 2nd Nitric (11 Mar to 2 Apr 2025)

  • Best phase in terms of recovery 71.29% and top rate 2.07 m³/hr.

  • However, steam economy further dropped to 1.68, and steam rate increased to 1.23 T/hr.

  • The drop in steam economy along with increased steam usage suggests fouling possibly remained in the tube side or partially removed.

• Overall Observation (29 Feb to 2 Apr 2025)

  • MEE-4 maintained stable operations over 50 days, with good recovery avg. 67.82%

  • Gradual increase in feed and top rate post hydrojet cleaning.

  • Increasing steam consumption trend with decreasing steam economy indicates need for improved fouling management.

• Graphical Reference: Refer Fig 3 in Annexure

Overall Comparative Summary – MEE-2, MEE-3 & MEE-4

To assess relative performance across the three MEE plants, key operational metrics from each system were compared over similar operational windows. The table below provides a consolidated view:

Note: Bold values highlight best-performing parameters among the three

Key Observations and Performance Insights:

• MEE-3, equipped with the Klaren self-cleaning system, outperformed the other units in terms of steam economy (2.02) and throughput (2.86 m³/hr). The TG- Klaren self-cleaning system effectively minimized tube fouling, maintaining consistent heat transfer and reducing cleaning-related downtime.

• While MEE-2 recorded the highest recovery (69.74%), it also showed the highest steam consumption (1.12 T/hr) and lowest steam economy (1.55). This suggests that despite higher water removal, the plant faced reduced thermal efficiency—likely due to fouling and suboptimal vacuum levels.

• MEE-4 demonstrated balanced performance, with steam economy (1.80) and recovery (68.51%) close to MEE-3 and MEE-2, respectively. This indicates that improved vacuum stability and better process control post-cleaning contributed significantly, even in the absence of self-cleaning technology.

• The steam economy advantage of MEE-3 validates the integration of self-cleaning as a long-term fouling mitigation strategy, supporting consistent performance across varying feed quality and operational disturbances.

• Vacuum conditions, bottom setpoint control, and cleaning schedules were identified as common influencing factors across all MEEs, impacting evaporation efficiency and recovery. Fine-tuning these parameters, along with real-time monitoring, is essential for sustained plant performance.