Environmental engineering for the elimination of industrial emissions

The baghouse filter retains particles using a porous textile medium, achieving efficiencies greater than 99.9% for PM2.5. The electrostatic precipitator ionizes particles and attracts them to collecting plates; its efficiency is high but sensitive to dust resistivity and gas temperature. The choice depends on the emissions profile, operating temperature, and available maintenance.

The wet scrubber is effective for soluble gases (SO₂, HCl, HF) and submicron particles, but generates a liquid effluent that requires treatment. The dry system (sorbent injection) produces no wastewater and is simpler to operate, although its capture efficiency is usually lower. The decision is based on local environmental regulations, the plant's water balance, and waste management costs.

The specific energy consumption of fans (kWh per Nm³ treated), system pressure drop, gas operating temperature, liquid-to-gas ratio in scrubbers, and actual capture efficiency versus design are measured. Maintenance records and performance curves of rotating equipment are also reviewed. The audit identifies deviations and proposes operational or engineering adjustments.

It starts with the flow rate and composition of the flue gas, the NOx concentration, and the required emission limit. SCR and SNCR options are compared considering capital costs (catalyst, injectors, structure), operating costs (reagent consumption, catalyst replacement), and maintenance. A life cycle analysis is included, and scenarios with different reduction levels (60–95%) are presented. The budget is delivered with a breakdown by items and an implementation schedule.