Abstract
It has been well documented that improved desalting efficiency reduces the risk of corrosion and vice versa. The work life balance of the refinery corrosion engineer is frequently challenged by concerns that the risk of overhead corrosion is increasing as refineries process more challenging crudes and run lengths increase.
One component of this problem is the risk of ammonia and amine salt formation. As the concentration of ammonia and amines increase, the probability of salt formation increases. Computer modelling is employed to calculate this risk and to assure the selection of a neutralizing amine used to control overhead pH does not also contribute to the risk of salt formation.
Traditionally however, the natural level of ammonia and amines that are present in the system, meaning those not due to addition of the neutralizer, has been a “given” in the risk calculation. They are typically monitored, but not controlled. The material balance of amines/ammonia is complicated, the level of these contaminants cannot be easily correlated with desalting efficiency.
This paper introduces a new way of using the desalting process to help control overhead corrosion. A new adjunct chemistry, fed in combination with the emulsion breaker is shown in case histories to be able to increase the removal of salt, ammonia, and amines in the desalter, reducing their levels in the overhead. The nitrogen compounds are removed in the desalter and leave the system in the brine. The end result is the corrosion engineer has a new tool to reduce the risk of salt formation. This will improve crude flexibility, refinery profit margin, and work life balance.
