Any pulp mill owner knows that energy is the third largest cost in production behind materials and labor. What they might not know is that evaporators are the biggest energy users in the pulp mill. About 40% steam needed per ton pulp goes to the evaporators. Older evaporators need about 33% more steam for the same amount of evaporation and produce less reusable condensate, leading to higher fresh water usage.
88% of pulp lines in North America are more than 30 years old and for evaporators, the average age is 40 years old. Many older mills have at least two evaporator trains, while newer ones are able to achieve five times the capacity with only one train. As evaporators age, the operating and maintenance costs continue to rise and efficiency falls.
The mills that will survive in the long run are the ones who can control their cost of production by limiting water and energy usage while maintaining evaporator efficiency. The best way to achieve this may be to undertake an evaporator rebuild and upgrade. By adding heating surface and upgrading condensate segregation, an upgraded evaporator plant can provide improved steam economy, a dry solids increase and an overall increase in capacity. The performance of an evaporator is directly linked to the mill water usage. An upgraded one produces clean condensate that can be reused in the mill process reducing the need for fresh water. This lowers costs and environmental impact.
Valmet is the market leader for evaporation equipment for chemical pulp mills, both for new trains and upgrades to existing trains. Upgrades are a good way to achieve improvement in performance that come close to what new train can achieve, but at a lower cost and making use of existing infrastructure. To find out more about how Valmet can upgrade and rebuild your evaporator, contact us today.
You’re already well aware that evaporators are the biggest energy hogs in your pulp mill. And while the evaporators may cost you most in the energy department, they can also be where you would see the most savings in production costs. These savings can be achieved when you modernize the evaporators, making both them and the entire mill more efficient and reliable. These benefits include Steam Economy, Condensate Segregation, and Scaling and Availability.
Steam Economy: Many older evaporators only have 5 thermal effect and some do not have the concentrators integrated into the evaporators at all! Modern evaporators normally have 6-7 thermal effects. Based on the cost of energy for an average North-American mill, the savings from upgrading from 5 thermal effect to 6 thermal effect, could be in the area of $1.9 million. More so, upgrading from 5 thermal effect to 7 thermal effect could offer a $3.3 million saving.
Condensate Segregation: Energy savings can also be found by improving the quality of the condensate from the evaporators. Condensate is contaminated by methanol, and that methanol will be released during the initial evaporation process. By producing a larger amount of clean condensate in the backend effects through internal condensate segregation, it can be reused in the pulp mill. Modern pulp mills reuse all secondary condensate, reducing water consumption.
Scaling and Availability: Scaling is something we know you would like to avoid. The plugging of equipment, increased energy costs and especially lost production due to the downtime are things we all want to avoid. Modernizing your evaporator can greatly reduce scaling.
There is no need to buy a new evaporator, when the one you own can be upgraded. Let the experts at Valmet be your guide to upgrading your pulp mill to be more productive and energy efficient.