Optimal catalyst performance starts with selecting the right catalyst for the intended operating conditions. Once the catalyst has been selected, it needs to be checked to confirm that the quality and quantity are in line with the offer and the reactor loading diagram. The reactor needs to be prepared for loading and the internals must be cleaned and inspected. The loading must be carried out by specialised companies, using industry best practices, and, preferably, supervised by an independent, experienced supervisor. The loading should be documented for future reference. After loading, the catalyst needs to be conditioned and activated for use. Once activation is complete, the catalyst can be used for production. It is important to respect the manufacturer’s instructions for running in the catalyst, gradually increasing the operating severity. Evidently, the catalyst is intended to demonstrate satisfactory performance throughout the anticipated (scheduled) cycle length.
Achieving that cycle length is an important factor in minimising unit downtime. For the reactor to reach that cycle length, the catalyst needs to be treated with respect and operated within the guarantee operating conditions. If the guarantee operating conditions are observed throughout the cycle, the supplier is responsible for meeting the cycle length. The unit can be monitored several times during the cycle to determine the actual remaining catalyst activity. Such unit-monitoring reports enable an informed decision on how to operate the unit for the remainder of the cycle. They also assist in deciding whether severity can be increased or should be reduced to achieve the scheduled cycle length. The catalytic unit may occasionally be exposed to conditions outside the guarantee conditions and it is important to assess whether those deviations will affect the remaining cycle length. If, for example, the catalyst is exposed to impurities in the feedstock that reduce catalyst activity, one issue might be the maximum amount of impurity that can be fed to the unit whilst still achieving acceptable conversion and cycle length.
Other possible issues include temporarily heavier feedstock, insufficient hydrogen coverage and the availability of only partial pressure, resulting in accelerated deactivation. At times, such circumstances are deliberate, at others they are simply unavoidable. It is important to realise that any deviation from the norm during the cycle impacts the remaining catalyst performance. It is therefore essential to monitor the unit’s performance regularly during the cycle and monitor the feedstock quality and operating conditions. This will help you gain not only a better understanding of the current cycle but also a better understanding of what a particular system can withstand in the event of a future cycle under similar conditions. Refineries and petrochemical plants aim for the maximum performance from their catalytic unit, to optimise short-term profitability without jeopardising the unit’s long-term performance. That requires a good understanding of which conditions are permissible and which should be avoided.
Catalyst Intelligence will assist you in achieving optimal performance from the catalyst unit, ensuring that it operates closer to its full potential, where maximum profitability is attained, while avoiding conditions that could result in a premature change out. Economic conditions can prompt a decision to consciously shorten the catalyst cycle by running heavier feedstocks or higher impurity levels. In such a situation, Catalyst Intelligence can assist in drafting the plan for the next change out, including revalorisation of the spent catalyst and selection criteria for the new batch.
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