Safety instrumented systems (SIS), as defined by ANSI/ISA-84.00.01-2004 Part 1(IEC-61511-1 Mod), are required to have components functionally tested and/or replaced/ refurbished under preventative maintenance (PM) to provide the reliability required to have a Safety Integrity Level (SIL) rating. SIL-rated safety systems are often required when a greater degree of protection layers is required then that offered by standard design.

Most hydrogen plants take the process condensate, send it to a deaerator to clean it up, and then reuse that condensate while mixing it with some boiler feedwater internally. There are configurations that have high pressure strippers where they will bring in some steam and do some initial stripping.

Some of the mitigation options can be summarized in four areas. The first is feed logistics. We would say that if you are going to handle this, you need to do as much direct feeding as possible.

The question of issues associated with waterwash has been discussed since the API-932 was issued. This first slide gives a little chronology of some of the documents.

The primary incentive is catalyst life and the ability to meet turnaround intervals. Gas and liquid distribution improvement results in increased catalyst performance and potentially longer catalyst life. Reactor internal upgrades may consist of quench decks, mixing chambers, and improved liquid distributor trays.

There were a number of questions this year that requested information about how to effectively utilize low-cost hydrogen to increase refinery volume yields.

At the Denver Refinery, we have a few hydrogen separation membranes. We call them our hydrogen purification unit. Our #3 HDS, which is currently our ULSD unit, was previously a gas oil hydrotreater until we revamped it in 2006. So, the HPUs (hydrogen purification units) were in consistent service from 1990 to 2006.

We are starting to hear about more foaming problems, particularly with some of the unconventional or shale crudes being processed, and there are a few other instances.

Factors limiting cycle life in low pressure kero/jet hydrotreaters are mainly related to product quality specifications. In particular, specifications related to aromatic saturation such as smoke point and color.

With an ebullating-bed reactor, the primary throughput limit is set by the superficial velocity, which is a function of reactor diameter and throughput. The superficial velocity is what determines the ability to separate gas from liquid going to the recycle pump.