Menasha Packaging is the nation’s largest independent, retail-focused packaging and merchandising solutions provider with a network of design centers, manufacturing plants, and pack-out and fulfillment service centers. Menasha Packaging collaborates with the world’s leading retailers and consumer packaged goods (CPG) companies to deliver the greatest measurable value across the entire integrated merchandising supply chain.
Menasha Packaging received assistance from the Spirax Sarco team when their Energy Services Group (ESG) performed a complete energy assessment — including a steam trap survey. ESG found ways for Menasha Packaging to save money by reducing its energy usage. To ensure that Menasha’s steam system operates properly and efficiently, ESG recommended a boiler blow down heat recovery package, steam trap replacement, and piping modifications to meet best practices.
After receiving assistance from the Spirax Sarco team, Menasha Packaging is seeing annual savings of $85K from prevented steam and condensate loss; $68K from blow down heat recovery; and $12K from prevented compressed air leaks.
Steam-heated roller problem
Part of the paperboard manufacturing process involves melting adhesive that bonds the surfaces together. Precise temperature control is critical. If the temperature is too hot, scorching of the paper and burning of the adhesive can occur. Not enough and inconsistent heat causes poor bonding due to uneven and un-melted adhesive. Steam-heated rollers must provide adequate and consistent heat to ensure quality products.
During the steam-trap survey, ESG found that the plant’s existing traps were undersized and not removing condensate adequately, resulting in scrapped and wasted production materials.
To solve this problem, the Spirax Sarco’s Energy Systems Division (ESG) worked closely with Paul Turner from Michigan Steam and Skip Lake from The Macomb Group to provide replacement steam traps, most of which were float and thermostatic with a Steam Lock Release (SLR) feature. The ESG team also incorporated sight check valves for visual inspection.
To ensure maximum heat transfer, condensate must be removed promptly. Otherwise, the heat transfer efficiency of the rollers is reduced. In rotating cylinders such as these heat transfer rollers, steam pockets can form in condensate removal dip tubes, which can prevent condensate from reaching the trap. This is referred to as “steam lock.” The SLR option bleeds the steam pockets from the system to effectively release the steam lock and enable proper steam trap operation and thus effective condensate removal.
By removing the condensate from the steam-heated rollers, the heat is now consistent, which allows the adhesive application process to operate as designed. Since the rollers — and consequently the adhesive — are heated uniformly, multiple paperboard layers now adhere properly.
Heat recovery saves energy
Spirax Sarco’s ESG team also provided a boiler blow down heat recovery package. Boilers require a method of controlling the amount of total dissolved solids (TDS) that form in boiler water as steam is generated. When the water conductivity exceeds a preset limit, typically a TDS system opens a valve to discharge boiler water. Feedwater with relatively low TDS replaces the discharged boiler water.
It is important to maintain a boiler manufacturer’s recommended TDS level in an operating boiler. This is accomplished by reading the TDS conductivity level of the boiler water and blowing down the boiler when this level exceeds specification. Blowing down a boiler basically throws valuable heat down the drain. However, a blow down heat recovery package such as those available from Spirax Sarco can prevent this energy from being wasted. In some cases, a blow down heat recovery system can recover up to 80% of the heat from the blow down cycle.
The blow down heat recovery package allows pressurized condensate from the blow down cycle to flash in a flash vessel and this steam is fed directly back to the boiler feed tank. In addition to energy savings from heat recovery, flash steam from blow down water is condensed to relatively pure water and goes back into the system, which reduces the amount of makeup water and chemical treatment required. A float trap drains the residual blow down condensate. This residual water is still hot and it is directed to a heat exchanger to warm cold makeup water.
The proof is in the savings
Spirax Sarco’s ESG team determined that the long startup times and cold spots on the rollers were caused by improper condensate removal. The new steam traps solved these problems. The traps also helped remove air from the system, which helped to dramatically reduce startup times. Additional savings were realized with the installation of the blow down heat recovery unit in the boiler room. Payback for the unit is less than a year.
According to an old saying, “if something sounds too good to be true, it probably is.” Spirax Sarco’s ESG team documented the estimated savings. In addition to providing quotes, drawings, and estimated savings, the team provided all the formulas and thoroughly explained the theories to multiple people at Menasha Packaging.
Menasha had a concern regarding the change out of the steam traps. As the existing traps were undersized and did not have the SLR (Steam Lock Release) feature, it was of no use to keep using the existing inventory. The SLR feature was a must in order to keep the rollers at the correct and consistent temperature. A few piping changes had to be made but these changes simplified piping geometry and actually saved space.
The team’s extra efforts worked for Menasha Packaging. Menasha’s energy savings and increased production convinced the company to have the Spirax Sarco team conduct a complete plant audit to find even more energy savings and process improvements. In addition to being able to take advantage of energy rebates from a natural gas supplier, Menasha realized the savings were so significant that they have replaced every trap on their corrugator.
Annually, the company is saving $85K from prevented steam and condensate loss; $68K from blow down heat recovery; and $12K from prevented compressed air leaks. Not only are the energy savings significant, but by installing these units, both the facilities and the environment will benefit as well.