Say yes to lower energy consumption and costs

Today, every mill is looking for ways to save energy - not only to cut down costs but also to reduce its carbon footprint.

author: Runtech Systems

Industry Insight by:

Runtech Systems Oy

Using vacuum in various paper machine positions is expensive. In fact, vacuum is one of the top three energy consumers in a paper mill. By using vacuum only in the most critical positions, you can fully benefit from a more efficient nip dewatering strategy and save energy. By measuring the water flow online accurately enables you to optimize vacuum levels and not overdo them. Heat recovery provides another way to save energy.

Using recovered heat instead of primary energy sources, for example, to warm up shower waters or dryer hoods allows you to expect major cost savings.
By optimizing your papermaking process, you can save energy up to 30-70% as well as improve runnability and paper quality.

Switch over from an LRP to an EP Turbo Blower

Did you know that the EP Turbo Blower is at least 15-30% more efficient than a new liquid ring pump (LRP)?
And as an LRP wears down, this difference grows. In typical rebuild projects, 40-60% energy savings have been achieved. Process optimization and lower energy consumption start with the EP Turbo Blower. This completely water-free vacuum solution offers significant heat recovery potential for paper machines. Mills have reported that vacuum system optimization with variable speed and capacity turbo blowers have saved them up to 2,000 kW. However, to save energy maximally up to 30-70% takes more than just switching over from LRP’s to turbo blowers. You need other optimization measures, too.

Engineered solutions for pulp & paper industry worldwide to ensure fluent and efficient papermaking process

A well-designed and operated dewatering and doctoring system is one of the key issues to a well-performing and energy-efficient machine. Runtech is one of the leading suppliers for the improved dewatering and doctoring solutions.

Measure water flow to optimize vacuum levels

To save energy, it is essential to use the optimal vacuum level in the forming and press sections. Often paper mills use too high vacuum levels because they do not know the accurate water flow. EcoFlow is the only reliable and accurate online dewatering measurement system for water that contains lot of air. When you measure the water flow accurately, you can adjust the vacuum optimally and reach high energy efficiency.

Go for nip dewatering

There are some additional ways to ensure optimal vacuum levels and thus save energy. By using nip dewatering instead of uhle box dewatering, you get better profiles and improve dewatering without vacuum. Here are some things to pay attention to:

  • Felt moisture ratio has to be high enough.
  • You need to have right type of felts.
  • Roll covers need to have grooves instead of blind drillings.
  • Well-functioning save-alls and doctors are a must to prevent rewetting. A doctor rebuild can reduce the need for vacuum by up to 50%.
  • Air Blades are suitable for lower machine speeds.

Optimized doctoring and dewatering improve process performance and dryness after press, lowering the need for steam (1% dryness means 4% steam savings). This, in turn, results in electrical and steam energy savings.

Recover and reuse exhaust heat

EP Turbo produces approximately 5 to 20 m3 of exhaust heat per second. By recovering this 100-180 °C heat, you will be able to lower steam consumption. Recovered exhaust heat can be used, for example, to warm up shower waters or dryer hoods. Since steam is one of the most expensive components in papermaking, heat recovery will lead to significant cost savings. Replacing primary energy sources by heat recovery reduces your carbon footprint as in many places steam is produced by combusting fossil fuels that cause CO2 emissions.

Take a look at these energy savings

  • Uhle box vacuum: 15 kW/meter.
  • Drive power (uhle box friction): 7 kW/meter.
  • Increase in dryness (after press) 1-2% equals to 4-8% less steam.
  • At least 25%, typically 40-60% electrical savings compared to LRP system.
  • Heat recovery energy savings rate: 80-200% of turbo system total power demand.
  • Water and cooling tower cost savings: 100,000 EUR/year.
  • Easy and fast maintenance of turbo blowers. Bearing exchange during felt change (8h). All maintenance can be done on site.

On average 2MW LRP system produces 3,500 tons of CO2 annually. With Runtech turbo rebuild you will also save 30-70% of these emissions.

Runtech Systems is a global provider of engineered systems tailored to the pulp and paper industries. Runtech’s patented solutions include vacuum system and heat recovery optimization, runnability optimization, dewatering, doctoring and cleanliness optimization as well as ropeless tail threading, including related services, spare parts and paper machine audits and consulting.

Heat recovery cuts down papermaking energy costs radically because the system reuses heat to replace primary energy sources.

 

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