Tissue & Paper Mill Hood Exhaust Heat Recapture System

1. Project Overview & Context

Heavy-duty particulate-tolerant condensing heat recovery system capturing 5.2 MW of waste heat from paper machine Yankee dryer hoods to preheat process water and hall ventilation air.

3. Objectives

1. Model high-temperature moist exhaust gas condensation in Aspen Plus. 2. Design self-cleaning spray condensing scrubbers to prevent paper dust clogging. 3. Supply preheated process water (65 °C) and hall makeup air (40 °C). 4. Cut mill natural gas consumption by 35,000 MWh annually.

4. Simulation Setup & Thermodynamic Selection

Aspen Plus multi-phase gas-liquid simulation with particulate holdup estimation. Sized heavy-duty stainless steel direct-contact towers and shell-and-tube economizers.

5. Process Flow & Reduction Chemistry

Aspen Plus multi-phase gas-liquid simulation with particulate holdup estimation. Sized heavy-duty stainless steel direct-contact towers and shell-and-tube economizers.

6. Model Input Variables & Boundary Conditions

8. Results & Findings

9. Engineering Discussion & Trade-Off Analysis

The self-cleaning design prevents paper dust from building up on heat transfer surfaces, providing uninterrupted 24/7 mill uptime. The captured energy preheats freshwater before it enters the boiler house and supplies low-pressure hot water to plant drying fans.

11. Environmental Impact & Decarbonization Value

Significant reductions in carbon emissions and fuel waste achieved through rigorous process simulation and heat integration.

12. Model Limitations & Scope Boundaries

Requires stainless steel construction to withstand trace organic acids in paper vapors.

13. Engineering Conclusions

Heavy-duty condensing heat recovery transforms paper mill exhaust liabilities into reliable, high-yield energy assets.

14. Future Development & Digital Twin Integration

Coupling with black liquor recovery boiler economizer optimization.