Allentown Cement Co. of Evansville, Pa., has a long history of cement production in the cement belt of the state's Lehigh Valley. The company was founded in 1900 at the site of a deposit of cement rock that is geologically similar to the well-known "blue stone" of the Lehigh Valley.

>From its original 1910 configuration of four, 8-ft-diam, 120-ft-long >rotary kilns, the plant has gone through several modernizations and >upgrades. The present plant configuration was installed in 1965 and >consists of two 520-ft-long, 15-ft-diam, dry-process rotary kilns, >supplied by Traylor. Each kiln's dust control is provided by mechanical >separation using cyclone-type separators followed by a large baghouse. >Kiln gases leave the baghouses through a large, covered mono-vent that >runs the length of the baghouse system. The dust collected in the >baghouses is then returned to the kilns.

Like most cement production facilities, Allentown Cement has been looking for opportunities to cut costs and increase its profitability. Among other cost-reducing programs, the company has installed an automatic kiln control system to increase the efficiency of the kilns and decrease the cost of fuel for each ton of clinker.

Upon reaching the point where additional gains in efficiency were impractical or impossible, Allentown Cement put together a project team to begin looking at ways to lower the cost of fuel. The team began investigating alternate fuels that could be purchased at prices lower than the normal coal/coke fuel prices. Wanting to be environmentally friendly in the process, team members searched for a fuel that was not only less expensive than coal but also beneficial to the environment and would not lessen the quality of the cement.

Another project team was formed to investigate and choose an alternative fuel source and install the necessary equipment to use that fuel source. Tires were one of the first alternate fuels investigated, and because scrap tires met all objectives, Allentown Cement decided to use them.

Allentown Cement then began looking at feed systems to deliver the tires to the kiln. There were two options for feeding tires into the kiln: a chipped-tire feed system or feeding whole tires into the kiln. The chipped-tire feed system used shredded or chipped tires that were blown into the kiln along with the coal. The whole-tire feed system fed whole passenger or truck tires through the shell of the kiln with a valve or gate assembly.

After weighing the pros and cons of each method, Allentown Cement selected a whole-tire recycling system from Cadence Environmental Energy. The Cadence system incorporates a feed-fork design to pick up tires and drop them into the kiln through a drop tube and gate assembly.

Chipped vs. whole tires

Allentown Cement looked at the advantages and disadvantages of each feed system:

CHIPPED-TIRE FEED SYSTEM Advantages 1. Established technology in use at many facilities worldwide.

2. Introduction of the fuels is in the traditional "burn zone" of the kiln.

3. Consistent fuel delivery system.

Disadvantages 1. Must purchase the chipped-tire-derived fuel.

2. Small particle size is required to burn the chips in suspension.

3. Quality issues associated with tire chips falling into and burning in the load.

WHOLE-TIRE FEED SYSTEM Advantages 1. Whole tires generate revenue.

2. Burning tires mid-kiln has no known negative quality issues and may be beneficial to the clinker mineralogy.

3. Flexibility to use other revenue-generating fuels.

Disadvantages 1. A new fuel entry point requires a different strategy and response to situations when burning in the kiln.

2. Questions about effects on the kiln of a fuel delivery system that delivers fuel once each revolution.

3. Maximum fuel replacement of between 15% and 25%.

There were several other reported benefits in using the Cadence Feed-Fork system that had to be verified at Allentown Cement. These include: improved clinker mineralogy, longer brick life in the burn zone, and reduction in NOx emissions.

In studying these systems, it came down to a question of economics and cement quality. Could Allentown Cement feed enough chipped tires so that the fuel savings would equal or surpass the fuel savings and revenue from feeding whole tires? For both systems, they concluded, the clinker quality could not be negatively impacted.

To satisfy these questions, Allentown Cement installed a system to feed chipped tires. In 1994, the company completed a trial burn using the chipped-tire-derived fuel. Upon examining the results of the trial burn, it was determined that the economics favored the mid-kiln system. There also were additional cement quality issues that made the chipped-tire system unattractive to the company.

Cost justification Upon making a decision on which technology to use for introducing tire fuel into the kiln, the project group set out to define the total capital dollars necessary to implement the fuel program. While this evaluation was taking place, a market study also was conducted to determine if tire industry pricing would support this capital project. What follows are the conclusions from these two studies.

Feed apparatus and automated feed system The project team reviewed a series of feed systems that either operated at other cement plants or at power stations. They ranged from fully manual feed systems to fully automated systems. The overall conclusion was that the more automated the system became, the less labor would be involved in the handling of tires.

Because the planned feed system included truck tires, there was some concern over a manual system. The tire feed can range in size and weight from 20 lb for a car tire to 150 lb for a truck tire. This range, particularly the weight of heavy truck tires, made manual loading a difficult option. In addition, the manual labor necessary to handle a 24-hr-per-day cement operation would require no fewer than two workers per shift to load tires into the kilns. Therefore, while a manual system would have been a much less capital-intensive option to install, it was a significant commitment to labor. The decision was made to install a fully automated system from the beginning of the project.

Through the project team's evaluation, the system of choice was one that involved the use of walking floor storage bins. These bins would be filled by front-end loaders and then feed a tire-collection device that would place the tires one at a time onto conveyor belts for transport to the Cadence Feed-Fork system on the kilns.

The project team then put out requests for proposals from tire system manufacturers, and Tire Management Inc. (TMI) was selected. Located in Dayton, Ohio, TMI's experience in installations at cement plants was a bonus to the economic evaluation. Typically, an automated installation is about $1.6 million. Due to the site and the configuration of the Allentown Cement kilns and process, it was believed that some modifications were necessary to optimize the energy recovered from the tires. These modifications may not be necessary on all kilns. With the cost of the Cadence feed forks, the automated feed system, site preparation, and kiln modification required for this particular kiln configuration, the capital project totaled $2,282,764. Figure 1 shows the breakdown on how the capital dollars were spent.

In the market survey, Allentown Cement attempted to determine if there was an adequate volume of tires to provide a consistent fuel supply and what the expected revenue would be from the scrap tire fuel.

The volume of tires in any given market is in direct proportion to the population that exists in the area. Since tires are usually loaded manually and brought in pickup trucks or box vans, the market radius for shipping tires to any facility is 75 to 150 miles. Competition from other tire users, however, can reduce this radius. With this in mind, the project team investigated and was able to target heavily populated areas, such as Philadelphia, Harrisburg, and Lancaster, Pa., as well as parts of New Jersey. It was determined that these areas could supply a more than adequate supply of tires.

The pricing in the market area can be influenced by several factors, including:

1. Transportation A decision had to be made whether to buy or subcontract trucks to transport the scrap tire fuel. Allentown decided to subcontract trucks for the transportation of tires.

2. Competitive End Users One large or several small end users competing for the same tire supply would negatively impact the market price of the scrap tires. Allentown Cement discovered a limited number of end users, but there were many businesses investigating starting tire operations.

3. Tire Dumping (or illegal disposal by small haulers) A large volume of tires disposed of illegally would negatively affect the price of tires.

4. Regulatory Funding Sponsored by Rep. David Argall, the state of Pennsylvania signed Act 190 in December 1996, which provided funding and tax credits on capital investments related to the cleanup activities of scrap tires.

In 1995-the same year the project team was formed-the price in the market was at $60 to $70 per ton. Unfortunately by the time the project was funded, the price had fallen to $25 to $40 per ton. The lower-end pricing was available if Allentown Cement had brokers deliver the tires, and the higher pricing was available if the plant took part in some or all of the sourcing of the tires. The disposal cost at the tire dealer location is consistently in the $100-per-ton range, while transportation costs to the kiln are in the $40- to $60-per-ton range.

The difference between the two prices is both the fee to the kiln and the profit to the broker. The price, or tipping fee, the cement kiln receives is dependent upon their level of participation in this process. It was the position of the Allentown Cement project team to pursue thehigher tipping fees and participate in sourcing the tires to its own facility.

The project team formulated a fuel replacement estimate of 15% of coal consumption, so as to derive a potential fuel savings of $450,000 per year. With an average tipping fee of $30 per ton, the total fuel replacement and tire revenue exceeded $1 million per year. This figure was within the parameters of the corporate payback guidelines. In the second quarter of 1997, the tire project was given approval for capital investment. The timing delay was due mostly to the issuance of the air permit to allow Allentown Cement to burn tires as fuel.

Air permitting and trial burn Whenever a new fuel is added to the kiln, or when a fuel is added at a new location, a revision to the air permit is normally required. Obtaining a new or revised air permit, however, can be an extremely difficult process. Regulators often look upon revision as an opportunity to ratchet down the emission requirements and implement new control policies.

However, when adding a scrap tire fuel, the cement company is normally in a much better position. Most states have a problem with disposing of scrap tires and are looking for a consistent disposal option. A single cement kiln can normally use more than 500,000 tires per year. Consequently, regulators are more willing to expedite an air permit and keep additional requirements to a minimum. So, Cadence supplied emission testing results from other kilns that had undergone testing. These circumstances helped Allentown Cement receive plan approval for its air permit relatively easily.

As part of obtaining the air permit for the new scrap tire-derived fuel, Allentown Cement was required to both perform a trial burn and report the results to the state's division of air quality. The test was performed from Sept. 4 to 6, 1996. Each kiln was tested in a coal-only configuration for the baseline condition and a configuration where one tire was fed per revolution at mid-kiln. There were three individual tests in each condition, for a total of 12 tests.

The State of Pennsylvania asked for emission data for CO, SO2, and NOx. As predicted by the results supplied by Cadence, there was an increase in CO emissions and a decrease in NOx emissions at Allentown Cement. The emission results are shown in Figure 2.

Supplier arrangements With the capital project approved and installed, and the plan approved for the air permit, Allentown Cement was ready to start commercial operations of the scrap tire feed and establish the network of suppliers necessary to provide the tires. As discussed previously, the decision at Allentown Cement was to source tires into the plant on its own. This decision was made to avoid additional capital investment in trucks. The market seemed full of trucking companies that serviced everything from small gas stations to large tire stores, so Allentown Cement formulated tire supply arrangements with large regional tire collectors and a few smaller local tire collectors.

The benefits for developing this strategy were the following:

1. Safety The primary concern at Allentown Cement's plant is safety. With constant traffic from trucks delivering stone, front-end loaders, and construction projects at the site, the company needed to develop a safety program. All tire suppliers were given an Allentown Cement safety plan. They are required to wear hard hats, safety shoes, and glasses and are only permitted in designated areas in the plant. Limiting the number of suppliers on site allows Allentown Cement to assure a safer management of tires.

2. Logistics on site Tire suppliers have limited access to the plant, so suppliers are instructed to bring only whole car, light truck, and truck tires into the plant. Also the tires must be as free of dirt and water as possible, and all suppliers must first check in with the central dispatch office. Suppliers are then given a weight ticket and must leave a copy of their paperwork for computer input. All loads of tires delivered to Allentown Cement must have paperwork from the supplier.

If loads are delivered from state cleanup sites, these tires are tracked separately. Tire suppliers are then sent to one of two unloading areas. The first is located at the walking floor bins, where mostly small trucks are unloaded by hand into the bins. The second area is a large storage cell that can accept large truckloads and be fed to the system by front-end loaders. Suppliers must weigh in and out of the facility and leave their weight slips with the dispatcher.

3. Collection of money From an accounting perspective, this was the biggest adjustment that Allentown Cement had to make. It is a common practice to receive a credit application, run a background check, and then set up payment terms with each vendor. Problems arose with small suppliers with limited assets, and it became important for the company to establish a cash payment policy with some of these suppliers. Certain suppliers are now required to pay for the weight of tires that they have brought to the plant upon delivery.

4. Inventory control One of the biggest challenges with tire deliveries is receiving whole tires that can be fed into the kilns. Most suppliers, even when informed that only whole car or truck tires are desired, will bring motorcycle, bicycle, and almost always torn or shredded tires. By limiting the suppliers and maintaining records of their delivery times, Allentown Cement can accurately track down and impose additional disposal fees on suppliers of bad tires.

Currently, Allentown Cement has 45 tire suppliers who fill the needs of the plant. Other tires, such as cleanup tires, are brought in by separate arrangement. The company also works with local communities on annual tire cleanups by accepting these tires at no charge. Any Allentown Cement employee is allowed to bring a limited amount of tires into the plant on a yearly basis. The company, however, does restrict local residents from bringing tires directly to the plant because of safety-related issues. These tires are directed to one the the company's existing tire suppliers to arrange for pickup and delivery to the plant.

Market area and competition Allentown Cement is able to receive tires from as far away as New York City. Obviously, in places where population is high, the supply of tires is greater than in less populated areas. Pricing has stabilized to about $45 to $55 per ton for car and light truck tires. However, the competition in the immediate market area is still not able to meet the demand for the amount of tires generated. The facilities currently competing with Allentown Cement are:

* A cement plant, 30 miles from Allentown Cement in Whitehall, Pa.

* A shredder, 50 miles from Allentown in Conshohocken, Pa.

* A cement plant, 130 miles from Allentown in Union Bridge, Md.

* A power plant, 135 miles from Allentown in Marmora, N.J.

* A cement plant, 140 miles from Allentown in Frederick, Md.

* A power plant, 300 miles from Allentown in Sterling, Conn.

While there appears to be intense competition for tires, bear in mind that the transportation of tires more than 100 miles from a tire-processing facility becomes noncompetitive. The only exception is the power plant in Sterling, Conn., which uses only tires for its fuel. This plant can use more than 300 tpd of tires, or 30,000 tires daily.

Since the power has been purchased at a set rate designed not to impact the tire price, this particular plant can receive tires from tire suppliers more than 250 miles away. It is believed that the other five facilities are receiving the tires needed to meet their demands.

Tire handling The handling of tires is probably the most critical step once a plant has decided that a market exists for favorable tire pricing. The handling of tires at a plant site is far more difficult than any other raw material delivered to the plant. Storage of the tires requires a large land area for trucks or stockpiles, and tire movement requires coordination with existing front-end loaders or additional capital in truck tippers. Finally, the transport method for introducing tires into the kiln and thereliability of that method are the most important pieces in the tire management program.

In addition, well-defined maintenance programs will limit downtimes or process changes related to fuel. Operator training on kiln burning should begin prior to the initiation of the tire burning program. This is probably the most overlooked area when beginning a tire fuel program.

Estimated tire revenue and fuel savings Based on current levels of maximum cement production, Allentown Cement has not yet maximized its tire replacement rates; the company's present maximum tire replacement rate is about 15%. With the cement plant in a sold-out condition, Allentown Cement has been maximizing its tire feed.

Allentown Cement is seeing a slight production loss with the way the company presently operates the system. It is believed that production loss due to mid-kiln fuel utilization is a product of operator training and kiln modification. Whenever there is a problem with the feed system or the kiln, the company has had a tendency to slow or stop the tire feed rather than work through the problem and maximize the scrap tire feed rate. When time permits, they will investigate and experiment with the mid-kiln technology, as well as develop the required training and procedures without the pressure of maximum production. Only then does the company believe it will be able to adequately address the production-loss issue.

The project startup was short of the projected average 15% replacement rate for both kilns. With 15% being the present maximum, the average is less than what the company had anticipated. In 1997, the average replacement rate was 7% for the year, and 1998 looked about the same. As has been indicated, this modest replacement rate is indicative of the company's pressure on production. Even with this nominal replacement rate, using a minimum $30-per-ton tire price for Allentown Cement puts tire revenue at $322,640 for 1997.

Part of the tire revenues are shared with Cadence to pay the licensing fee and royalties for use of the mid-kiln system. The fuel savings were about $300,000, for a total of $632,640 for 1997. Consequently, Allentown Cement fell short of its original capital payback projections. However, tax credit savings, which were not part of the original projections, have more than made up for the shortfall.

Allentown Cement believes that this program has been successful because it is generating revenues with the system. The kiln runs smoothly and the mid-kiln system has worked dependably. Allentown Cement is now looking at expanding its alternate fuel program to include waste streams that it hopes will bring in even higher revenues than does the tire-derived fuel program.