Dryer Seals are Key to Efficient Production
During the cold of winter when you are running your furnace to heat your home, would it be HVAC-efficient, environmentally helpful or financially wise to leave some of your windows open? Of course not.
Yet for closed controlled systems on a much grander scale, hundreds of industrial direct heat dryers are operated every day without being effectively sealed. Drum Seals which are either absent, poorly designed or damaged often contribute to excessive gas flow through the drum due to air leaking in. Such exhaust gas leaks in the rotary drying process increase fuel consumption (to heat the excess air), increase material carry-out (due to higher gas velocity), place a heavier burden on air pollution equipment and increase operating expenses.
Furthermore, these leaks reduce product quality, fuel efficiency and even production capacity. (Common causes for seal failures are abrasion/contamination, shell expansion/contraction, excessive shell run-out, poor maintenance and product overflow.)
The Problem with Air Leaks
Rotary drums, dryers and kilns serve a crucial role in the processing of hundreds of various consumer products including bulk solids and chemicals. Since dryers utilizing heat transfer in these controlled systems operate with internal temperatures much higher than ambient air, any outside air allowed to leak into* the vessel will reduce the operating temperature and cool the gas stream, thus reducing the overall effectiveness and cost-efficiency of the system.
Furthermore, unintended changes in the processing temperature alter the intended chemical reactions – which negatively affects the state and quality of the end-product.
* Note: When rotary dryers are operated as designed to be under slight negative pressure, out-gassing will be reduced, i.e. leakage of heat and combustion gases from the vessel will be minimized.
Specific Examples of How Air Leakage Affects Dryer Efficiency
The 1” gap around the end circumference of this drum shell can cause an air leakage of approx. 5,400 ACFM, which places an unnecessary/avoidable significant burden on the baghouse and fan, resulting in loss of 10-15% of production capacity.
The air leakage allowed by the 1 ½” gap (from missing seals) on this 8 ft. diameter drum is equivalent to a 1’ 9” square hole (= 3.1 sq. ft.) in an exhaust duct!
Poorly maintained (or absent) seals contribute to poor performance and loss of efficiency
The Louisville Dryer Solution
We button up your plant with high-quality durable seals
To close the gap between our rotating vessels and their stationary discharge housing, we custom-design and install seal systems. Our application engineers emphasize that properly designed and maintained seals are a significant contributor to the system’s overall efficiency and can thus provide a relatively prompt ROI for plant owners/managers who invest in them.
If your direct heat dryer does not have a seal system – or is missing leaves/sections of its existing seal, contact us soon to request a diagnostic inspection and solution recommendation from our engineers.
Benefits which your plant could realize from installing/maintaining a proper seal system for your rotary drum/dryer:
- Decreased production expenses
- Lower maintenance costs (from reduced gas volume/velocity and fan wear)
- Saved MBTUs
- Raised flame temperature
- Increased production capacity
Types of Dryer Seals
When it comes to seals, clearly one size does not fit all. Louisville Dryer Company can offer many different types of drum sealing devices specifically designed to meet the needs of the application process – considering factors including operating temperatures, material in process, dryer size and rotational speed.