Pushing ESP boundaries

Introduction:

We have had an opportunity to work with another reputed cement manufacturer located in Rajasthan. The clinker cooler gases were led into an ESP, which was originally designed for achieving an emission of ≤ 50 mg/Nm³. The client had to meet the recent norms of ≤ 30 mg/Nm³ emission from the ESP. The client was also proposing to install a WHRS system after the clinker cooler, where the gases from clinker exhaust will be led into the WHRS and the gases from the WHRS outlet will be taken into the ESP for control of particulate matter. The existing ESP was designed for a volume of 4,87,200 m³/h at an inlet temperature of 280 ⁰C. The existing ESP is a 3 field ESP, with 14.5 m collecting electrode height and a gas velocity of 0.69 m/s.

The ESP was not performing as per the designed emission norms due to some internal problems. Clair was handed with the task to achieve an emission of ≤ 30 mg/Nm³ for the conditions specified in Table 1 with the installation of WHRS.

Data/ Table:

Table 1: Design parameters of Clinker Cooler ESP

Observations:

Clair took up the challenge and following solution was proposed and implemented:

• A new parallel ESP was proposed along with the existing ESP to provide for additional treatment time to achieve an emission of ≤ 30 mg/Nm³. The existing ESP would handle volume as per achieving the emission of ≤ 30 mg/Nm³ and the remaining volume will be handled by the New ESP (parallel to the existing ESP). Accordingly the new ESP was designed for a volume of 1,70,520 m³/h at an operating temperature of 280 ⁰
• The new ESP was provided with new ID fan and was connected to the existing stack
• The existing ESP was also studied to improve the performance and achieve the emission as per the design parameters. Accordingly CFD analysis for gas distribution was performed and new GD screens were provided
• Internal inspection was carried out and damaged electrodes (both discharge and collecting electrodes) were replaced with new electrodes. Alignment of the fields was also done
• Existing TR sets were replaced with new TR sets with advanced controllers
• Existing rotary air locks were checked for any leakage and were replaced with new ones
• Inlet and outlet ducting from respective tapping points to the new ESP was provided. CFD analysis was performed for the complete ducting arrangement to make sure the pressure drop across the system was minimal and also the gas flow was uniform

Clair successfully implemented and commissioned the installation of New ESP in parallel to the existing ESP to achieve the emission of ≤ 30 mg/Nm³. Since it’s commissioning the clinker cooler ESP is operating successfully as per the designed emission norms.

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