Weirton Steel: Mill Identifies $1.4 Million in Annual Savings

Following Plant-Wide Energy-Efficiency Assessment

Summary

The Weirton Steel Corporation began a plant-wide energy assessment of its steel mill plant

in Weirton, West Virginia, in the fall of 2001 and continued assessment studies through

most of 2002. The main objectives were to identify energy saving projects that would reduce

the large expenses for fossil fuel and electricity. (In this case study, “fossil fuel” refers to a

variable combination of blast furnace gas, natural gas, and fuel oil.) These resources are 

used in many applications to heat or dry steel, in producing steam, and in pumping water.

Weirton Steel recently pursued other efficiency enhancement programs in response to

intense global competition; this plant-wide energy assessment continued the company’s 

on-going pursuit of energy efficiency. Based on the assessment results, the company found

strong economic justification for six projects that would reduce the use of fossil fuel, 

electrical energy, and water. 

The continuous annealing (CA) lines have steel strip washers and strip dryers that consume

large amounts of heated water and steam-heated air, respectively. Four of the six projects

proposed alternatives for conserving these resources. Other projects seek to optimize furnace

operation and reduce the cost of comfort heating for workers in the tin mill. All of the 

proposed projects would reduce fossil fuel requirements for heating steam or firing the 

furnace. This savings totals 108,000 million British thermal units (MMBtu) annually or 

nearly $1.3 million. Other yearly savings include 119 million gallons of water ($87,100) and

84,000 kilowatt-hours (kWh) ($3,360) of electrical energy. All of the projects could be

applied to other steel mills and possibly other industries using steam processes and furnaces.

Public-Private Partnership

The U.S. Department of Energy’s (DOE) Industrial Technologies Program (ITP) cosponsors

plant-wide assessments through a competitive process. DOE promotes plant-wide energyefficiency assessments that will lead to improvements in industrial energy efficiency, 

productivity, and global competitiveness, while reducing waste and environmental emissions.

In this case, DOE contributed $100,000 of the total $200,000. 

Company Background

Headquartered in Weirton, West Virginia, Weirton Steel has been in existence since 1910. It

is the largest industrial employer in the state of West Virginia and is the eighth largest steel

producer in the United States. Weirton Steel provides an extensive array of tin mill and

sheet steel products as well as steel products for the building and construction market to

customers worldwide. The company also sells high-quality galvanized steel to manufacturers

of steel framing for residential and commercial applications. Because of intense global 

competition, the company is under great pressure to produce its product more efficiently.

This pressure led to Weirton’s decision to upgrade its facilities and streamline its production

processes to significantly reduce energy usage. 

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BENEFITS

• Identified savings of about 108,000

MMBtu of fossil fuel energy annually

• Identified savings of about $1.4 million

annually by reducing energy 

consumption 

• Identified paybacks ranging from 3 to

23 months, depending on the project

APPLICATION

The Weirton Steel Corporation plant-wide

energy assessment focused on the 

technical and economic potentials for 

using alternative energy sources, such as

“waste heat,” in various energy-intensive

processes. The assessment team 

evaluated 1) the continuous steel 

strip drying operations, 2) fossil fuel 

consumption in furnaces, 3) personnel

comfort heating costs, and 4) reduction 

of water booster pump operating costs.

The projects identified in these systems

could be replicated in other steel plants

and in certain other energy-intensive

industries.

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Assessment Approach

Weirton Steel began efficiency improvement studies and implementation programs on its compressed

air system and control system modernization in the late 1990s. Because of tremendous pressure to

remain competitive in the global market, even as these programs were being implemented, the 

company began the much broader plant-wide energy efficiency audit process in 2001. The audit goals

were to identify cost-effective, energy saving projects relating to 1) the strip drying operations 

adjacent to the annealing furnace in the tin mill, 2) reducing fossil fuel use in the annealing furnaces,

3) reducing comfort heating costs in the tin mill, 4) reducing Weirton River water booster pump

operating costs, and 5) steel preheating (warm charging) in the reheat furnace. 

In performing the plant-wide energy efficiency assessment, Weirton Steel hired the technical analysis

services of White Hat Engineering and Diagnostic Solutions, LLC. Weirton directed these project 

partners to look at numerous potential projects and identify those that 1) provide a high return on

investment with a short payback, 2) require only modest capital investment, and 3) can be implemented with minimal disruption to production. This last requirement meant that the projects can 

be phased in, one at a time, on individual lines of the continuous annealing process, and the 

modifications would not require extensive alterations to the furnace structure. 

The Weirton Steel assessment team helped provide the other teams with access to processes and the

necessary information to support analyses. The team members, who had extensive knowledge of the

processes, equipment, and batch runs at the Weirton plant, also carefully evaluated all of the studies.

Results

Weirton steel operates three CA lines in one section of the Tin Mill. Each process line feeds steel strip

through various operations to create a properly sized, high-quality, uniform product with the desired

material properties. The assessment team successfully explored options for reducing the consumption

of steam, electricity, fossil fuel, and water in the CA lines. The team also identified ways of reducing

the cost of comfort heating in the tin mill. For several other processes, the team will continue to

investigate new or emerging opportunities.

Table 1 lists projects that show the greatest promise based on the assessment team’s analyses. It also

lists the primary savings whether they are energy or utility (such as water), the project cost, the estimated savings, and simple payback shown in months. Since line 1 operates only 700 hours per year

compared to 7,500 hours for lines 2 and 3, most line-specific projects are based on the two more

active lines. The first project, which recycles most of the heated water that is sprayed on the strip,

provides the greatest cost savings by far. The savings are primarily thermal in each case, translating

into reduced usage of fossil fuel and less plant byproduct gas emissions. All of the projects have a

simple payback of less than 2 years. 

Projects Identified

The following discussion details the selected energy-efficiency projects developed during the plantwide assessment. Because of the similar basic processes used in steel plants, all of the projects are

highly applicable throughout the steel industry. The projects may also be replicable in other industrial

plants that use energy-intensive thermal processes.

Project 1 – Recycling final wash and rinse water

The strip washers at the infeed end of the annealing furnaces use large amounts of filtered river water

that must be heated to 180°F. The back section, consisting of the No. 2 scrubber and final rinse, loses

all of the sprayed water to a drain. This represents a loss of 200 to 500 gallons of heated water per

minute for the three lines. White Hat Engineering recommends installing a new system that would

capture and recycle the water at the wash line. The system would include a low-pressure pump, a
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hydrocyclone to clean the water, a high-pressure pump to create a pressure of 150 pounds per square inch (psi), and a

booster heater to return the water to 180°F. Assuming that the new system saves 80% of the water that would have

been lost to the drain, the net thermal energy savings would be 66,244 MMBtu annually for the three lines combined.

The system would also save 113 million gallons of water annually. 

Project 2 – Reduce strip dryer air flow and improve instrumentation

The CA process in lines 2 and 3 feeds steel strip through a wash

before it enters the annealing furnace and the strip is quenched

in water as it exits the furnace. However, immediately before the

furnace and also after the quenching, the strips must be dried to 

prevent rust and discoloration in the final coiled steel product.

Both of these drying operations use two hot-air strip dryers that

obtain hot air from steam coils. The entire steam heat transfer

and hot-air blowing operation is manual and runs at maximum

continuously. The 75-horsepower blowers produce 4,400 standard

cubic feet per minute per dryer and the air temperature is about

135°F. The assessment team concluded that this non-regulated

operation is oversized by a factor of about two and needs maintenance. The team’s primary recommendations are to clean the

heating coils and begin experiments to regulate operation of

selected dryers. The team estimates that, by following their 

recommendations, Weirton could save at least 15% in total cost,

with much higher savings likely. Most of the savings would be

thermal, with annual savings of at least 3,950 MMBtu in steam

and at least 84,000 kWh savings in electricity, for the combined

lines 2 and 3.

Project 3 – Use furnace stack gases to dry strip

This project builds upon Project 2 by using waste heat (annealing furnace stack gases) instead of steam heat to dry the

strip before it enters the annealing furnace. To protect the two blower fans in each line from excessive temperatures,

the stack gases would first be mixed with ambient air. The project would save 13,180 MMBtu annually for the combined

lines 2 and 3.

Table 1. Estimated Project Cost, Savings, and Payback for Projects at Weirton Steel

Recycle final wash and rinse water Thermal/ 225,000 780,000 3 (Lines 2 & 3)

water (3 lines) (3 lines) 20 (Line 1)

Reduce strip dryer air flow and improve Thermal/ 58,000 55,000 13

instrumentation electric (2 lines) (2 lines)

Use furnace stack gases to dry strip Thermal 130,000 120,000 13

(2 lines) (2 lines)

Use annealer slow-cooling air to dry Thermal 180,000 120,000 18

strip (2 lines) (2 lines)

Repair and adjust annealing furnace Thermal 260,0001 180,000 17

Modify comfort heating system in the Thermal/ 81,000 100,000 10

tin mill (steam)2

Total 934,000 1,355,000

1 A rough estimate that may vary from $180,000 to $340,000.

2 Replaces steam heat with electric heat in order to attain this cost savings.

Primary Project Annual

Resource Cost Savings Payback

Project Conserved ($) ($) (months)

Hot-Air Strip Dryers for a Continuous

Annealing Line (Project 2)
BestPractices is part of the Industrial Technologies Program, and it supports the Industries of the Future strategy. This strategy

helps the country’s most energy-intensive

industries improve their competitiveness.

BestPractices brings together emerging

technologies and energy-management best

practices to help companies begin improving

energy efficiency, environmental performance,

and productivity right now.

BestPractices emphasizes plant systems,

where significant efficiency improvements

and savings can be achieved. Industry gains

easy access to near-term and long-term

solutions for improving the performance of

motor, steam, compressed air, and process

heating systems. In addition, the Industrial

Assessment Centers provide comprehensive

industrial energy evaluations to small- and

medium-size manufacturers.

PROJECT PARTNERS

Weirton Steel Corporation

Weirton, West Virginia

West Virginia University

Morgantown, West Virginia

White Hat Engineering

Morgantown, West Virginia

Diagnostic Solutions, LLC

Knoxville, Tennessee

FOR ADDITIONAL INFORMATION, PLEASE CONTACT:

Industrial Technologies Clearinghouse

Phone: 800-862-2086

Fax: 360-586-8303

clearinghouse@ee.doe.gov

Visit our home page at

www.oit.doe.gov

Industrial Technologies Program

Energy Efficiency 

and Renewable Energy

U.S. Department of Energy

Washington, DC 20585-0121

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FOR A STRONG AMERICA

Energy efficiency and clean, renewable 

energy will mean a stronger economy, a

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with a wide array of state, community,

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Department of Energy’s Office of Energy

Efficiency and Renewable Energy invests in

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January 2004

Project 4 – Use annealer slow-cooling air to dry strip

This project, like Project 3, builds upon Project 2 by using waste heat (from the

annealer slow-cooling air supply) to dry the strip. In this case, the drying would take

place immediately after the furnace and quenching stages. The project cost is somewhat higher than for Project 3 because the cooler air temperature (roughly 220°F)

necessitates larger ductwork. The mixing equipment and controls are included in

the estimate but may not be necessary. (A longer-term temperature profile is needed

to determine this.) The project would save 13,180 MMBtu annually for the 

combined lines 2 and 3.

Project 5 – Repair and adjust annealing furnace

Based on numerous observations, the assessment team concluded that the 

annealing furnaces for lines 1 and 2 were in disrepair and significant amounts of

excess, unheated air were leaking in. The team recommended burner repair, damper

repairs, and balancing the combustion system based on rough but conservative cost

estimates. In this limited assessment, no thermal savings estimate was calculated.

Project 6 – Modify comfort heating system in the tin mill

The heating system in the tin mill keeps workers comfortable by dispersing steamheated air. However, much of the heat rises to the roof, doing little good for the

workers at floor level. The White Hat Engineering team proposed replacing area

heating with localized electric radiant heating at 150 work zones. Timers or motion

detectors will control each of the radiant heaters. Although electric energy will

replace the fuel-heated steam energy, the thermal energy reduction (11,780 MMBtu

annually) and cost savings justify the project. 

Steam Heater for the Tin Mill (Project 6)