Numbers don’t lie. Sustainability means better business.
This paper tells a true story of how significant energy savings can be achieved in the day-to-day operations. This is also a story of how achieving a responsible future is a profitable business.
Energy is one of the largest cost items in any pulp & paper mill. It is also a significant source of CO2 emissions. Reducing steam consumption has a direct impact both on reduced emissions and increased profitability.
A leading group in the pulp & paper industry is committed to a responsible future, which means using natural resources more efficiently. One key target is a 10-index point improvement in energy efficiency.
Pioneering Evaporator Efficiency
Traditionally reducing steam consumption has not been a focus with certain types of evaporators. Two engineers from the leading pulp & paper mill had made calculations that energy efficiency could be improved by smarter operations.
In early 2022, the engineers decided to test their theory at one of the group’s facilities. A pilot service for optimizing a specific evaporator system was launched together with the HeatHamster team. HeatHamster team had experience in optimizing energy efficiency in heat exchangers, but this had never been done with this type of evaporators. So, there was a lot to learn.
Learning by doing. Do it differently. Analyze the impact.
After a couple of months of trials and errors, the learning process found its routine. HeatHamster team analyzed the data and planned a clean-up schedule for every week. The lead engineer involved the operators, making sure they understood the impact of their work. Each activity was discussed and documented.
Before the summer of 2022, several different combinations were tested. Different amounts of chemicals. Shorter and longer clean-ups. Different cleaning sequences.
The impact of all activities was monitored and analyzed by real-time data from the HeatHamster software.
Surprising Insight. Dynamic Clean-up Schedule.
A year later in the spring of 2023, there were enough tests and measurement data to compare the before-after impact of the new way of running the operation at the pulp & paper facility’s specific evaporator system. The surprising insight was the importance of a dynamic cleaning sequence.
There are two traditional ways to initiate a clean-up of an evaporator unit. Calendar-based, where a unit is cleaned after a fixed time, or measurement-based, where a unit is cleaned when ΔT reaches a specific limit. Trying to optimize either one of these sequences did not yield any significant improvement, no matter how much and which chemicals were used.
Only after learning a dynamic schedule and a “triangle-shaped” sequence, the number of clean-ups per month was reduced and the steam consumption was reduced. The physical reason behind was related to the complex transfer of sediments between the units.
3,761 tons of CO2 saved with profitable day-to-day operations
Numbers don’t lie. So, let’s look at the hard numbers of the one-year operation at the specific evaporator system.
The number of monthly clean-ups was reduced from 24.3 to 18.9. Each removed clean-up saves water, chemicals, and costs. Steam usage was reduced by 17.6%, from 16.5 MW to 13.6 MW. With a 20 €/MWh energy cost, this means 331.2 k€ in annual profits. CO2 emissions are reduced by 3,761 tons per year due to lower energy demand.
In the beginning of 2022, the engineers had the thought of improving energy efficiency of an evaporator by smarter operations. One year later, this idea has been proven to be true. Sustainability can be achieved through smarter day-to-day operations.
The group is taking these learnings to other sites, with more evaporators being already under work.
Most importantly, the group has proven that sustainability is not a cost, even in the short term. It is a profitable way of running operations.
