During paper production, fibre is suspended in water to form a pulp, which is then moulded to the required shape. In a process known as de-watering, a vacuum is used to remove excess water before the paper enters a drying oven. The level of bacteria in the process water affects the de-watering process: higher levels of bacteria increase the production of “slime”, which blocks the sieve and hinders water removal. Typically, paper enters drying ovens with a ratio of 40% fibre to 60% water. The higher the water content, the more energy is required to dry the paper.
Watson-Marlow saw an opportunity to increase energy efficiency and in 2018, Huhtamaki, a paper manufacturer in the Netherlands, participated in an on-site trial to establish the energy saving benefits of using Qdos pumps to accurately dose lime into the water, preventing bacteria growth.
The trial demonstrated that with accurate lime dosing, the de-watering process reduced the water content of the pulp. This enabled Huhtamaki to reduce the drying oven temperature by 15°C, generating a 3% energy saving, reducing carbon emissions by approximately 18,000kg per year and delivering a return on investment of just four weeks.
Customer case study
Australia helps customer reduce gas use by 23%
In a drive to increase energy efficiency and reduce gas consumption at their meat processing plant in Dubbo, New South Wales, Fletcher International Exports identified steam system efficiency improvements as an effective way to rapidly reduce gas consumption. Working with Fletcher’s on-site engineering team, Spirax Sarco identified four key areas for improvement 1) recover flash steam and reuse it in other processes, 2) increase condensate return, 3) increase boiler house efficiency and 4) improve steam distribution.
The engineered solution designed by the project team had significant benefits, which were measured and verified by independent, third-party engineers.
As a result of the installed solution, gas consumption reduced by 23%, saving an estimated 27,000 gigajoules of gas per year, equating to monthly savings of approximately AUS$45,000 (over £26,500), or AUS$540,000 (£319,000) per year. In addition to energy savings, boiler water consumption is expected to reduce by eight million litres a year and chemical use has also been reduced, saving a further AUS$10,000-15,000 (£6,000-£9,000) a year. Including installation, the project is expected to have a payback period of 12 months or less.
Customer case study
Spirax Sarco Mexico saves Nestlé energy and reduces water consumption by 28,000m3 per year
When specialist engineers from Spirax Sarco audited the steam system at Nestlé’s instant coffee plant in Toluca, Mexico, they were asked to develop and install a solution to recover 100% of condensate from distiller bells and to increase steam system efficiency.
The audit found that condensate was being lost as a result of back pressure being imposed on the condensate line by a flash steam recovery vessel. Spirax Sarco installed an automatic pump trap to overcome the back pressure, enabling the existing flash vessel to function correctly. Flash steam, generated in the flash vessel, is now used to preheat water before it enters a newly installed Easiheat™ unit, which is producing hot water for the plant. The condensate from both the flash vessel and the Easiheat™ unit is now returned to the boiler house (saving energy, water, and water treatment chemicals) where it is used to generate steam.
The solution cost Nestlé £76,000 but is saving £67,000 per year. In addition, it is reducing energy consumption at the plant by 6,700 gigajoules per annum and is saving 147 tonnes of CO2 emissions each year. Furthermore, improved steam system efficiency has reduced water consumption by as much as 28,000m3 per year.
Mr Ricardo Morales, Energy Manager at Nestlé Mexico, explained, “We are making investments to increase our energy efficiency. Each year in Nestlé Mexico we have the objective of saving around 4% in the use of energy and water. The participation of Spirax Sarco is key to improving the energy efficiency of our company in matters relating to steam production and distribution, condensate recovery, heat exchange and delivering expert training to our staff”.
Customer case study
Twenty-one Bredel hose pumps installed in landmark sustainable energy project
During 2016, Dong Energy completed a landmark project to convert its coal fired power station in Studstrup, Denmark, to sustainable biomass. Twenty-one Bredel hose pumps from Watson-Marlow have been installed at the site, helping Dong Energy to supply green district heating to around 106,000 homes and green electricity, equivalent to the annual consumption of approximately 230,000 homes, to the Danish grid. The project is also expected to reduce the plant’s carbon emissions by 310,000 tonnes per year.
To generate green energy, the site combusts sustainably sourced wooden pellets. When burned the pellets produce alkaline gases. To counter this a fine coal ash, reclaimed from landfill depositories, is added to the pellets prior to combustion. Dosing the ash requires pumps that can handle the thick, abrasive slurry produced when the ash is mixed with water.
Bredel peristaltic hose pumps were selected after trials demonstrated their superior ability to overcome the challenges associated with pumping the high density, inhomogeneous and abrasive particles, compared to large double-acting hydraulic pumps. Engineers from Watson-Marlow worked closely with Dong Energy and the site contractor Eurocon to deliver an optimised engineered solution to extend hose life, reduce costs and deliver reliable pumping in this innovative and sustainable energy project.