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Close guard against chloride issues (TIA)

Chloride removal monitoring and maintenance associated with the catalytic reformer unit (CRU) has long been a headache within a refinery.

Rravan Pappu
Johnson Matthey
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Article Summary
Impacts within the CRU and downstream can include corrosion and ammonium chloride salting, both of which can have significant impact on the reliability and profitability of the refinery. One refinery reported water washing the CRU stabiliser monthly at a cost of $100 000 per water wash – a problem too costly to be ignored. For this purpose, chloride removal beds have been installed in CRU units globally to adsorb chlorides and protect downstream users.

These chloride guard beds, however, have continually plagued refineries and have proven to be a costly distraction to engineering, operations, and maintenance personnel. One of the critical problems with chloride removal management is the lack of adequate sampling capability. Many refiners use popular, commercially available gas tube detection methodologies. These methodologies are not effective at measuring sub-ppm and are unable to detect organic chlorides. This means that operators are unable to “see” the chlorides leaving the unit to downstream users, leading to the undesired practice of “downstream problem based changeout”.

Johnson Matthey has introduced a better way to measure chlorides in the refinery. The Puracare chloride test kit is a gas tube methodology that allows for complete detection of inorganic and organic chloride down to 0.1 ppmv. The test kit is easy to use and cost effective (less than or equal to currently utilised methodologies) and allows refiners to utilise the methodology at-site for regular monitoring. This has been a game changer within the catalytic reforming unit in the ability to detect changeout and optimise material loadings.

One recent application was at a European refinery CCR unit which operates with a chloride guard on the net gas stream. Initial installation was promoted alumina, which characteristically exhibits reduced capacity and increased tendency for organic chloride formation. The maintenance team was dealing with continual water wash operations downstream of the bed to remove ammonium chloride deposits. One key issue was the lack of ability to measure when the chloride removal media was spent or producing organic chlorides. The Johnson Matthey team provided the Puracare chloride test kit for onstream sampling and detected, at the time of testing, the presence of HCl and organic chlorides on the inlet along with organic chloride content on the outlet. This meant that chloride species were travelling downstream and already causing damage in the form of corrosion or salting.

Based on this result, the site chose to change the ineffective chloride guard and install Puracare Clear chloride guard products. Specifically, Perform 1 and Purasieve 2 were utilised (see Figure 1) to address the HCl and RCl content and greatly increase the run length. Testing after it was in service for several months had shown that HCl and RCl content were present on the inlet but that there was no breakthrough on the outlet, which coincided with an elimination of the maintenance water wash activity. See Table 1 for the generalised testing results (numbers stricken for confidentiality).

The Puracare approach is to provide effective material selection and enable refiners to see the benefit. Measurement was and continues to be a key barrier in the industry. Johnson Matthey’s Puracare chloride test kit allows a refiner to overcome that barrier, enabling engineering, operations, and maintenance to make decisions based on improved information. In the end, time saved eliminating material changeout or reducing maintenance activity is time utilised towards other activities in the refinery.

This short case study originally appeared in PTQ's Technology In Action feature - Q3 2017 issue.

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