Ammonia Recovery in a Nitrogen Fertilizer Plant
A global nitrogen fertilizer manufacturer in the USA experienced continual performance issues in one of their natural gas nitrogen production facilities. The company transforms natural gas into ammonia through a cation/anion Higgins Loop semi-continuous ion exchange process that selectively removes all ammonia ions out of the wastewater. Once removed, the ammonia is recovered for fertilizer and the clean effluent is safely released into the environment. Although highly effective for ion removal, the loop exerts a lot of mechanical stress on the resin. The customer's resin was being crushed and required frequent change-outs to maintain effectiveness. To further complicate matters, the existing supplier was consistently unable to satisfy orders in a timely manner. The company's distributor got involved to source new resin and called Purolite.
Purolite learned that mechanical stability issues with the existing cation and anion resin persisted since the plant went online—approximately 25 years prior. Several competitive resins were tried over the years, all having the same result of persistent degredation. Purolite's resin would need to improve performance by withstanding the mechanical forces and harsh environment of the Higgins Loop ammonia removal system—and be delivered fast to keep the plant running and in compliance.
- Competitive cation resin did not withstand rigors of Higgins Loop system
- Continually replaced resin; purchased tons every year
- Resin fines caused pressure drop issues
- Experienced significant downtime in the plant
- Change-outs were operationally ineffective
- Damaged resin did not remove all of the ammonia ions from wastewater leading to discharge compliance issues
- Existing resin supplier unable to deliver replacement resin in a timely manner
- Caught in an expensive operating cycle of replacing and disposing of resin in a short time span
In March 2014, Purolite performed a complete PuroPass™ system review and audit and recommended a high-capacity, high-strength resin—Purolite® C160H. Side-by-side laboratory comparisons were performed for crush strength on both their existing resin and Purolite C160H to prove that this polystyrene-based macroporous strong acid cation resin would not only have the durability needed to withstand the Higgins Loop, but also have the capacity required to completely remove the NH3 ions for an extended period of time. Test data proved that Purolite C160H outperformed any cation resin this customer used for this application in the past with fewer fines, fewer damaged beads and more capacity.
In February 2015, all existing cation resin was removed, and an initial charge 800 ft3 of Purolite C160H was installed. Additionally, a change-out of the filtration system was undertaken to ensure that no existing fines would corrupt the new process.
The customer confirmed that their total resin orders for maintenance were cut by almost 60%. Quantity purchased was also reduced by 50%. This amounts to a $140,000 reduction in resin costs alone over 4 years. Additional significant savings were achieved in plant downtime, man hours and resin disposal costs.
By providing a better product for a challenging system, Purolite was able to save this plant a lot of money and aggravation. Instead of worrying about resin, they are able to focus on production, and their wastewater is cleaner and safer.
For superior products, a dedicated and knowledgeable sales force and on-time delivery, contact your local Purolite office.
