As the Foamfrax Grade I Insulation was being installed, it was immediately troweled smooth and scored. The score marks were placed at junctures of the lining corresponding to the flue and burner locations.

With the price of natural gas and oil at historic highs, now is the time for owners and operators of high-temperature furnaces to re-examine their options regarding energy efficiency in order to reduce heat loss and save energy. In 2006, Unifrax (manufacturer) introduced a “Save Energy Campaign” that highlights the company’s energy-savings products and technical competencies designed to help end users evaluate current furnace-lining systems and select more efficient options to save energy.

The Furnace Audit Procedure

The goal of the Save Energy Campaign is to develop solutions for end users that utilize innovative Fiberfrax® products. A key component of this campaign is the furnace audit procedure developed by the manufacturer. Using heat-transfer programs, field measurements and the new furnace audit computer program, Unifrax and its distributors can evaluate a specific furnace and accomplish the following:
  • Measure actual conditions, including current lining components and the cold-face operating temperatures
  • Perform theoretical heat-flow calculations to match the actual conditions
  • Verify current heat-loss measurements in terms of Btu loss/year and $ lost/year based on current fuel cost
  • Recommend improvements in the lining configuration (products, thicknesses, veneers, etc.) that will reduce energy costs while maintaining or improving the structural integrity and longevity of the lining
The data collected in this audit is used by experienced Unifrax engineers to provide a valuable analysis of the furnace-lining performance and make recommendations to increase furnace efficiency by utilizing a furnace upgrade or refractory replacement with an improved lining system. A computer-modeling program presents the results in terms of BTUs saved as well as the actual dollar savings that can be realized.

Fig. 1. Furnace audit form for documenting customer furnace conditions

How it Works

Once the heat-flow calculations have been generated for the current and proposed linings, this data is entered into the Furnace Audit Program along with the furnace conditions from the customer’s operation (Fig. 1). The output from this audit program is a set of graphs that compares the thermal performance and fuel costs associated with the existing and recommended linings. In addition, the program calculates the annual fuel savings that result from the lining upgrade.

In summary, the furnace audit is the key tool in the company’s Save Energy Campaign, offering our customers the following opportunities:
  • Address key needs of each end user
  • Provide a technical analysis
  • Customize an approach that maximizes energy savings and upgrades cost
  • Utilize a wide array of products that solve end-user problems

Energy Audit of a Roller Hearth Furnace

Since early 2006, the manufacturer has been involved in many furnace audits that have helped customers evaluate the best lining alternatives using a quantitative, engineered approach. A recent example involves a roller hearth furnace. Working with the customer, the Unifrax sales engineer and a local contractor performed an audit that predicted anticipated energy savings using updated products. After relining the first 28 feet of the furnace (20% of length) with the new approach, the customer was delighted with the concept, and the actual results (Table 1) surpassed the audit prediction. The results of a module/Foamfrax® lining installation are very effective. The Foamfrax technology provided fast installation, and the numerous sidewall openings were ideally suited for the Foamfrax insulation approach. Other benefits of this installation were quicker heat-up and cooldown and a more uniform heat within the furnace.IH

For additional information:
Unifrax I, LLC, 2531 Whirlpool Street, Niagara Falls, NY 14305; tel: 716-278-3800; fax: 716-278-3900; web:; email Brian Bradley is engineering manager, of furnace related products.

Fiberfrax®, Foamfrax® and Anchor-Loc® are registered trademarks of Unifrax I, LLC.

Additional related information may be found by searching for these (and other) key words/terms via BNP Media SEARCH at furnace lining, cold-face temperature, heat flow, energy efficiency