Air treatment equipment, like compressed air dryers, are vitally important to the production of high quality compressed air. Unwanted substances, such as moisture, can enter the piping system when air is compressed. Depending on the final use of the compressed air, moisture can cause contamination of or damage to the end product.
Twin tower desiccant air dryers are a common form of compressed air treatment used to reduce the amount of moisture within a piping system. The operation of a twin tower desiccant air dryer can be broken down into a three-step process:
The adsorption of moisture by a chemical desiccant while the gas is under pressure;
The release of moisture through depressurization; and
Purging dry or heated air through the desiccant in a regeneration cycle.
Integrated Components Affect the Efficiency of the Desiccant Dryer
During the air treatment process, there are six technologies that affect the efficiency of the twin tower desiccant dryer. Understanding the key components that contribute to increased energy efficiency will help you reduce maintenance costs and increase your energy savings in the long-term.
Filtration is a key component to the long-term operation and energy efficiency of a twin tower desiccant dryer. Not only will proper filtration reduce long-term maintenance costs, but it also increases dryer efficiency thereby increasing the effectiveness of the dewpoint control system.
A sonic nozzle helps to avoid damage to the desiccant and boosts dryer performance by limiting the volumetric flow into the dryer and matching it to the design flow of the entire unit. A sonic nozzle is necessary for critical applications such as multiple compressor/dryer installations, systems with regular start/stop or fluctuating air demand, a standby compressor without standby dryer or an incorrectly dimensioned dryer (too high air flow/too low working pressure).
Butterfly inlet valves reduce pressure losses by lowering restriction in the valve lines. The durable design of the highly reliable butterfly valves – over the less efficient angle seat valves – provides ongoing operational savings and reduces maintenance costs.
A dew point controller lengthens the time between regeneration cycles, reducing the amount of air that is needed to purge the desiccant bed.
An integrated controller collects detailed dryer performance data in addition to dryer operation and alarm conditions indicators. This information can help compressed air users determine the most effective use of the dryer and increase energy efficiency by streamlining processes.
A Zero Purge dryer design involves a blower that cools the desiccant after the heating stage, rather than using process air. The cost of running the cooler is significantly less than the cost of generating compressed air, therefore reducing overall operating costs.
Air losses due to purge and pressure drop are key focuses for energy efficient design improvements because they often represent a higher portion of the dryer operating cost than direct power. Choosing a twin tower desiccant dryer that incorporates technologies to reduce losses while maintaining optimal dryer performance can help reduce the overall cost to operate the dryer.
