Team Minimac successfully executed a critical project to re-condition the control fluid (tank capacity 16 KL) for a 2*600 MW coal-based thermal power plant in Chhattisgarh.

Synopsis

The plant establishes, operates, and maintains a thermal power generating station in Chhattisgarh. There was a problem with higher Total Acid Numbers (TAN), observed typically when moisture content exceeds the permissible range. They were facing difficulties in stable unit operation because of the sluggish and erratic behavior of the turbine governing system. It was a significant threat to generation loss and unit outage. The situation was examined by Minimac Operations and Maintenance Service (MOMS). Three machines - Nitrogen Blanketing TMR unit (100 LPM), Oil purification MLC-LVDH-TRIX (50 LPM), and TAN reduction— Resin filter modified in cartilage format were deployed to address the issue.

Oil Purification	TAN Value	NAS Value	Moisture
Before Oil Purification	0.23 mg KOH/gm	10	678 PPM
After Oil Purification	0.07 mg KOH/gm	6	250 PPM

The major challenge faced during the execution was if we charged resin, TAN will reduce, but moisture would increase. So, an analysis was done and implemented to control the moisture first, then charged the second resin cycle. Minimac gave a 100% customized solution within time.

Problems

The tank capacity was 16k liters, which was huge. The biggest challenge was to execute the project during running operations. Because for moisture control, it was necessary to turn off the system. Water bubbles were forming, leading to the fluctuation in NAS. Resin charge means moisture increase, and our motto was to bring moisture below 500 ppm so we can plan for the next cycle of resin charge.

Client’s Requirement

• To purify the control fluid.
• To reduce the TAN value from 0.23 to 0.08 mgKOH/gm.
• To reduce the moisture levels.
• To achieve NAS 6.
• Smooth and timely execution without any downtime
• Customized solution
• No spillage

Solutions

• The Nitrogen Generation Unit (TMR) was deployed and installed at the client's site. The salient features of the TMR unit are - 99.9% pure nitrogen, a dew point less than -15 degree celsius, and a dedicated moisture condensing unit.


• For Nitrogen Blanketing, TMR – 100 LPM had a flow regulator of 0-150 LPM


• Oil purification machine MLC-LVDH-TRIX-50 for NAS & moisture reduction was installed.


• Installed 12 new resin filters for TAN reduction in existing recirculation units


• Before the oil conditioning process, the TAN >= 0.210 mg KOH/gm (Electronic method) and 0.246 mg KOH/gm (manual titration), which was reduced after oil purification to TAN <= 0.097 mg KOH/gm (Electronic method) and 0.124 mg KOH/gm (manual titration)


• For further improvement in TAN, the oil vapor extraction fan(OVEF) was throttled in the range of 50-55%, with the support of the user


• They had an LVDH machine, and the NAS standard to be maintained as per the PO was 10+. We gave a better result without the replacement of the NAS filter


• Minimac provided trained manpower and other consumables under the MOMS (Minimac Operations and Maintenance Service) offering. Minimac has charged resin in an 8-cycle with 3 hrs intervals. 24hrs resin charge KPI was 0.074 mgKOH/gm.

Cost Saving

This plant managed to save:

• Cost of oil replacement: ₹3.2 Cr approx.
• Cost of downtime: ₹3.15 Cr approx.

By investing ₹9 lakh only

CO2 e Saving

1,92,000 kg of CO2 e / 0.192 gigagrams of CO2 e

Benefits

1. Extended in-service oil life.
2. The smooth functioning of the machines
3. Elimination of new oil replacement cost.
4. Avoiding the risk of fire and explosion.
5. Reduction in the possibility of product degradation due to blanketing

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