Increasing cogeneration in Canadian pulp and paper mills: PART II - NEW INSTALLATIONS IN NON-KRAFT MILLS

In Canadian pulp and paper (P&P) mills, cogeneration relies heavily on backpressure steam turbines found in kraft mills and other mills with a large thermal load. However, cogeneration does not necessarily have to rely on steam turbines, especially in non-kraft mills. To explore this opportunity, CanmetENERGY conducted a research project to determine which types of cogeneration investments would allow additional electricity generation in these mills. For many non-kraft P&P mills, one of the greatest opportunities is to extend cogeneration to thermal hosts that are too hot to be suitable for steam-based cogeneration, such as flash pulp dryers and tissue dryers. In these cases, a gas turbine can be used to produce electricity. The turbine exhaust can be sent directly to these dryers, and/or used to heat a thermal oil loop that redistributes the heat in the dryer and in other parts of the facility It has been estimated that, just for the three Canadian Bleached Chemical Thermo-Mechanical Pulp (BCTMP) mills powered by high-CO2-intensity electricity, gas turbines could replace 50 MW of grid electricity using less fuel than a combined cycle. Organic Rankine Cycle cogeneration is also of interest in specific applications. Cogeneration is a highly energy-efficient approach to produce heat and power at the same time. However, cogeneration projects can increase reportable CO2 emissions, which can affect their long-term viability in the context of rising CO2 prices and falling off-peak electricity prices.

Automated summary

In Canadian pulp and paper mills, cogeneration primarily relies on backpressure steam turbines, but can also be achieved using gas turbines for electricity generation. Extending cogeneration to high thermal load non-kraft mills, utilizing gas turbines and technologies like Organic Rankine Cycle, presents significant opportunities for development.