ENG. ANDREW OMWENGA

Section 1.0 — Simulation & Facility Metadata

Section 2.0 — Executive Summary

Flue gas and spray dryer exhaust condensing heat recovery system recovering 2.4 MW of low-grade thermal energy to generate continuous 80 °C Clean-In-Place (CIP) washdown and boiler feed preheating for a major dairy processing plant.

Section 3.0 — Problem Statement & Operating Bottlenecks

Dairy milk powder spray dryers discharge high volumes of warm, humid exhaust air (85–95 °C) laden with latent moisture and residual powder particulates. At the same time, the facility consumed heavy fuel oil and steam to heat 45 m³/h of fresh water for pasteurization and CIP sanitation loops, wasting over 20% of total site fuel input through boiler and dryer stacks.

Section 4.0 — Objectives & Rigorous Simulation Methodology

Rigorous thermodynamic spray scrubber model in Aspen Plus with multi-component water-air psychrometrics. Coupled with Aspen EDR plate heat exchanger sizing to isolate process-contact wash water from exhaust gas condensate.

Section 5.0 — Simulation Results & Thermodynamic Findings

By capturing the latent heat of water condensation within the spray dryer exhaust, the condensing heat recovery system dramatically outperforms standard dry economizers. The recovered heat satisfies 100% of the facility's daytime CIP sanitization duty, smoothing boiler firing loads and preventing thermal shock during shift changeovers.

Section 6.0 — Core Engineering Takeaways

Section 7.0 — Model Assumptions & Future Recommendations