Processing Magazine

How properly utilizing your dryer can help expand your business

January 23, 2007

Business is going great and production requirements are increasing daily. Production is optimizing every piece of equipment in the line to pick up every last bit of capacity to maximize output. Your company’s sales call for an increase in capacity. However, your unique situation may prohibit adding a new line. If the production bottleneck is your drying equipment and a capacity increase is critical, there are several options to consider.

Refurbish, expand, or buy new?

All are practical options. Depending on the condition of your existing equipment and the available space in your facility, it’s worth considering an upgrade refurbishment or expansion as a simple and cost effective solution for your production needs.

Step One: Update the Baseline

Whether your drying equipment is three years old or thirty, many things may have changed from its first day in operation that effect its performance. The original product specifications and even the types of products you dry may have changed, so it is import to update your equipment’s performance baseline. When examining how to keep up with operations, the first step is to evaluate your existing equipment from a process and mechanical standpoint. Many times, there are simple fixes that can be made to increase energy efficiency and also boost capacity. The heat source’s ability to maintain and exceed setpoint temperatures is critical when determining if the equipment has the capability to produce more. Product characteristics such as moisture content can vary sporadically or on a long term basis. Recognizing these variations will help you evaluate the equipment’s operating performance today versus its initial installation.

For an accurate baseline to determine how much more capacity your drying equipment can handle, have the equipment evaluated and inspected. Some manufacturers have evaluation programs in place and will send an engineer to your facility for little or no cost. Take advantage of the manufacturer’s customer service to help answer questions and assist with your equipment.

Can I Refurbish or Upgrade?

In many cases, a dryer refurbishment can bring production capacity back to its original design specifications – and potentially beyond. Depending on the dryer’s current condition, an upgrade refurbishment may consist of eliminating airflow short-circuits and replacing recirculation fans, heat source, conveyor components, internal panels and external doors, etc. Can the existing equipment be upgraded? If more production is the goal, upgrading the heat source and increasing the recirculation and exhaust airflow may help. Will that be enough?

The Need to Expand

When all resources have been exhausted and more production is still required, an expansion to the dryer can be a cost effective option. Most drying equipment in operation has the capability to be expanded. Expansions to drying equipment are a very common practice in today’s ever-changing production world. There are many benefits to expanding your drying equipment. Depending on the required production increase and future goals, an expansion to an existing dryer can cost significantly less than a new piece of equipment. One of the most common benefits to expanding a dryer is the reduced need for plant modifications. Examine how much open space is available around the existing dryer. While a dryer can be moved and expanded, the cost will be reduced with fewer pieces of equipment requiring relocation. Depending on the plant layout, often minimal changes to upstream and downstream material handling are required. If necessary, the exhaust fan may be upgraded and any additional ducting can be combined with existing ducting. If supplementary electrical controls are required, they can often be placed inside the existing control panel.

Minimize Downtime During Expansion

Most expansion units are built at the dryer manufacturer’s facility and shipped to the destination for installation. The expansion module’s frame is designed to match the existing dryer. All components can be constructed using the same material of construction as the existing unit. At installation, the existing dryer is separated at a designated point and the expansion module is inserted. Expansions require minimal downtime and can be installed within several days.

Process Parameters

In conveyor dryers, heated bed area is the most reliable scale-up factor when considering increases in dryer capacity. For example, a 33% increase in bed area should give a 33% increase in capacity – provided that other parameters such as inlet moisture, exit moisture, product density and bed depth remain the same. Apart from an increase in conveyor speeds, the process parameters can remain unchanged, with no product characteristics being affected. In other styles of dryers, capacity may be proportional to the number of trays, the heated surface area or other parameters.

Supporting Your Decision

Some dryer manufacturers will work with production and operations personnel to determine the existing equipment’s current capacity and what actions are essential to reach the desired production goals. During this process, the dryer manufacturer can determine if a refurbishment will meet your production goals or if an expansion will be required. Product specifications, current dryer design and existing physical condition will dictate whether more exhaust, cooling or any auxiliary equipment will be mandatory. The dryer manufacturer will be able to work with your specific product to determine the proper sizing for the increased water removal and appropriate configurations for the expansion.


The dryer should never be the bottleneck in your operation. There are cost effective options available if production requirements are increasing and the dryer has been pushed beyond capacity. Follow these steps to determine the requirements for upgrading or expanding.

  • Evaluate the drying equipment to determine if there is more capacity available.
  • Consider if a series of simple fixes or an upgrade refurbishment will allow the dryer to meet future production requirements.
  • Investigate the option of an expansion to the existing equipment and its benefits to your process. A dryer expansion can be a low risk solution to your production challenges, and help expand your business.

Going through this process will help you make an educated decision whether to buy new equipment, or increase the capabilities of your existing dryer.

David J. Reynoldsis a Parts & Refurbishment Engineer for Aeroglide Corporation. Reynolds has a B.S. in Mechanical Engineering from North Carolina State University. He has evaluated hundreds of convection conveyor driers and conducted drying theory classes in many different industries all over the world. He can be reached at P.O. Box 29505, Raleigh, NC 27626-0505 USA. Email: Telephone: +1 919-851-2000.