how to Extend the Service Life on Drever Industrial Furnace Ammonia Dissociators

Posted by Tom McDevitt on Aug 30, 2016 7:00:00 AM

A Drever Ammonia DissociatorTM functions to break down anhydrous ammonia into its component parts – nitrogen and hydrogen.  This is accomplished by introducing ammonia vapor to a suitable catalyst at high temperature.  Drever Ammonia DissociatorsTM are designed and manufactured to perform this service, and with routine maintenance, the units will continue to perform reliably over a long period of time.  It is the definite recommendation of The Rose Corporation that only metallurgical grade anhydrous grade ammonia be used in our Drever Ammonia DissociatorsTM.

Production demands vary creating fluctuations in a manufacturer’s demand for dissociated ammonia. At times when dissociated ammonia is not required it has been determined that the best practice is maintaining the dissociator at operating temperature with a small flow of ammonia passing through the unit.  Doing this extends the service life of both the dissociator’s catalyst chamber and heating elements.

In cases where multiple Drever Ammonia DissociatorsTM are used to supply required quantities of dissociated ammonia, it is recommended to distribute the demand between the multiple dissociators rather than leave one or two units idle while drawing larger quantities from the remaining units.  If it is not possible to maintain dissociators “on-stream” during stand-by, it is highly recommended to allow a small flow pass through the catalyst chamber(s).  This flow may be burned off through a line as illustrated with your dissociator’s piping schematic, or vented to atmosphere outside the building.

If plant procedures are such that maintaining low-flow status for the dissociator is not feasible, an alternate would be to idle the unit(s) without flow at a reduced temperature below 700o F (371o C) and above 1500o F (816o C).  The temperature range between 700o F (371o C) and 1500o F (816o C) is not recommended as this is the carbide precipitation range.

Routine inspection and maintenance will keep an ammonia dissociator operating at optimum performance.  The Rose Corporation recommends the following equipment, when supplied, be regularly inspected as follows:

  • Temperature Control Instruments – check monthly and replace yearly; follow manufacturer’s recommendations on other maintenance checks
  • Thermocouples – check monthly. Chromel-Alumel thermocouples do not fail-safe. Off-calibration thermocouples should be immediately replaced
  • Contactors and relays – check monthly and replace immediately if malfunction is noted
  • Brickwork, Heating Elements, and Catalyst Chamber – yearly
  • Strainers – remove and clean screens weekly or as necessary
  • Reducing and regulating valve – inspect valve seat for dirt and repair or replace if valve sticks and does not regulate properly
  • Relief Valves – inspect yearly, verifying release at set pressure, and repair or replace if defective

Following these basic recommendations will extend the service life of your Drever Ammonia DissociatorTM

 

The Rose Corporation’s Industrial Furnace division manufactures for customers world-wide all types and configurations of industrial furnaces such as batch type reheat and forging, tip-up, roller hearth, bell, car-bottom, vacuum, electric arc, and many more for both atmosphere and non-atmosphere, batch and continuous applications.  The Rose Corporation has manufactured industrial furnaces under both our RoseTM  and DreverTM  furnace brands, as well as manufacturing customized furnaces to our customer-supplied design.  We also manufacture dissociative, atmosphere generating equipment. 

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