Pulp & Paper

The following summaries are examples of cost reduction opportunities that Kinergetics staff have addressed for clients.

Kinergetics Discovers Significant Cost Reduction Opportunity, AFTER Completion of Pinch Study

Pinch Analysis is a respected and viable method of identifying process energy cost reduction opportunities in the pulp and paper industry. However, like any simplified methodology, it does have its limits. During a Facility Opportunity Assessment five months after another firm completed the Pinch Study, Kinergetics founder Tom Tucker identified an opportunity to reduce steam consumption on a liquor evaporator in the recovery area of a pulp mill. The annual savings was estimated to be in the range of $750,000 to $1,000,000 per year with an expected simple return of one year.

In another area, the mill Power House, the Pinch Study correctly identified boiler blow down as a viable source of 150-psig “flash steam” to help reduce fuel costs. However, flashing of steam at 150-psig also provides high temperature condensate that was NOT considered in the Pinch Study. Discussions with mill staff indicate that there is potential for reuse of this condensate for makeup water preheating, providing an annual savings of approximately $200,000 per year with a simple return of less than one year.

Energy Assessment Reveal Waste Heat Recovery Opportunity

Kinergetics specializes in waste heat recovery strategies for the process industry. An assessment at a Wisconsin paper mill revealed high temperature whitewater being discharged to drain. After identifying the potential value, Kinergetics was contracted to prepare a preliminary design and detailed cost estimate, and assist the mill with a Capital Funds Authorization. Mill Management stated that due to internal time constraints, “This project would very likely not have moved forward were it not for Kinergetics involvement.” The project was approved by Corporate, for an annual fuel savings of over $80,000 and a simple return of approximately 1½ years.

Optimization of Evaporator Vacuum Systems

Many liquor evaporators use two-stage steam jet ejectors to provide a source of vacuum for removal of non-condensable (NCGs) gases. Steam-jet ejectors are inefficient compared to electrically driven liquid ring pumps, but were often used due to their simple operation and low first cost. Liquid ring pumps can be a viable alternative but care must be given for proper selection. Assessment of applications at numerous pulp mills involving replacement of ejectors have offered simple returns in the range of one to two years. It is worth noting that based on discussions with internationally known pulp and paper process engineering firms, the majority of European mills specify liquid ring pumps as a matter of practice, and that North American mills tend to use steam-jets.

Thinking Outside the Box…

The primary goal of Kinergetics is to identify ways to reduce the cost of operations. Depending on how energy is supplied, this may take several forms. A recent assessment at a paper mill which was purchases steam from a local utility indicated return condensate heat recovery to be a viable means to reduce operating cost. The opportunity existed because the condensate was being returned at a higher temperature than required by the steam purchase contract. Numerous points of use were identified, including reduction of pocket ventilation fan fuel use. The estimated annual savings was in the range of $200,000, with a likely simple on the order of two years.

Combustion Testing Uncovers Air Preheater Tube Failure

Testing equipment is routinely used by Kinergetics to validate assumptions and locate problem areas. At a Kansas paper mill, combustion testing on a superheated steam boiler indicated excessive levels of exhaust oxygen. A detailed analysis around the economizer and air preheater indicated that one or more of the air preheater tubes had failed, causing reduction of the exhaust temperature into the economizer and reducing boiler efficiency. Visual inspection confirmed the tube failures, repair of which would provide an annual savings of $55,000 with a simple return of less than one year based on a quote obtained by the mill.

Effective Use of High Temperature Condensate

Use of high temperature process condensate near the process steam application can eliminate “flash steam” and distribution system heat loss. During a Facility Opportunity Assessment at a large Pacific Coast pulp and paper mill, an opportunity was identified to recover flash steam from condensate in the basement of a steam turbine room. The estimated annual cost reduction was $200,000 with an expected simple return in the range of one year. Use of an existing flash vessel helped to minimize expected implementation cost.

Improving the Performance of a Wood Fired Boiler

During a Facility Opportunity Assessment, mill staff raised concerns about a natural gas fire tube boiler that had been converted burn wood. Since the conversion, it had not been possible to operate the boiler at it’s deign steam output. Boiler efficiency testing and evaluation of combustion air requirements revealed that the likely cause was combustion air starvation. The recommended correction was retrofit with a larger combustion air fan motor and a variable frequency drive (VFD). The mill accepted this recommendation as a viable solution, which offered a return on investment of approximately two years.

Low Cost Opportunities Abound…

Not every project requires capital investment to reduce operating costs. Many mill compressed air dryers rely on electric heat for regeneration of desiccant columns. The column heating times are normally controlled to prevent over drying of air. However, failed controls or calibration issues can increase the cost of operation. A Kinergetics assessment revealed such an opportunity. Correcting the control problem to minimize excessive operation of the 40-kW heaters provided an estimated annual savings of $7,000 with a simple return of less than one year. Please see the Project Examples – “Low / No Cost Opportunities” for others.