Hydrocarbon Engineering

March

2017

HYDROCARBON

ENGINEERING

Hydrogen

Hydrogen production is critical to achieving the

hydroprocessing goals of a refinery. As middle distillate

processing continues to increase around the globe,

hydrogen production and availability continues to

become more strategic to the refining operation. In a

hydrogen plant, the steam methane reformer (SMR) is

the work horse in achieving the hydrogen production

demand. It needs to offer flexibility, while providing

efficient operation and avoiding responses to operating

conditions that can create unscheduled turnarounds

within the major hydroprocessing turnaround cycle. In

general, the monitoring of SMRs is still a dated

operation. Shift operators will look inside the firebox of

the reformer at some daily frequency and track the peak

tube wall temperatures using a single point optical

pyrometer (Figure 3).

Johnson Matthey monitoring technologies provide the

operator both a convenient and comprehensive snapshot

of the SMR firebox temperatures, as well as a continuous

monitoring of the SMR process side temperatures. The

reformer imager (Figure 4) provides 100 000s of

validated/high quality temperature readings from each

SMR firebox access point. These readings can be

compared and contrasted along the individual SMR tube

and three dimensionally across the SMR tubes and tube

rows. This offers the operator a high quality snapshot of

their reformer to determine areas to optimise their

reforming operation, whether in turndown, a seasonal

operating condition, or even gauging the ability to meet

the next major turnaround.

While the SMR firebox operation does manage the

reliability of the SMR, there are process side changes that

can impact reliability of the SMR during major turnaround

cycles. These can be feedstock slate changes, SMR

convection section changes, feedstock purification

changes, and the dynamic of transients in operation.

These changes and dynamics can impact operation

quickly (within 15 – 30 minutes of operation), which may

not be readily seen on the typical control indicators near

entrance and exit to the SMR. There is also a lag time for

the SMR firebox temperatures to respond to these

changes. This lag time has been enough to result in

damage to the SMR or at least severely damage the SMR,

forcing an unscheduled turnaround (Figure 5).

Johnson Matthey has developed CatTracker

for

reformers with Daily Thermetrics to enable this process

side monitoring within the SMR tubes. By working with

Daily Thermetrics, this technology can be loaded into

SMR tubes using a patented technique enabling process

side monitoring within the SMR tubes. The CatTracker for

reformers is a multi-point thermocouple device that

provides the highest quality process readings within the

SMR tube. Placing the catalyst tracking technology in

2 – 4 tubes within a hydrogen plant SMR provides the

operator with a new ‘sight glass’ into the SMR operation.

The CatTracker responds more rapidly to SMR changes

than the SMR outside tube wall temperatures. These

readings are of high thermocouple quality and have been

validated with established SMR modelling. The response

sensitivity is further seen with the tracker for reformers

temperature response to a change in feedstock

purification and sulfur slip to the SMR (Figures 6 and 7).

There are other operations within a hydrogen plant

that can impact turnarounds, such as process gas boiler

leaks and high temperature shift fouling. The potential

cost and time savings of identifying or verifying a

potential mechanical or process related problem prior to

a major turnaround is substantial. It requires extensive

plant process data analysis, online process diagnostics and

modelling of potential process changes and the probable

Figure 5.

Catastrophic SMR tube failure and SMR

single tube failure.

Figure 4.

Reformer imager device.

Figure 3.

Single point pyrometry.