At the Emerson Exchange Americas Virtual Series, a North American refiner’s Transformation Manager teamed up with Emerson’s Scott Baruch to present a case study on how wireless flare monitoring assisted their plant turnaround efforts and improved ongoing flare gas recovery unit (FGRU) operations. Here is the case study’s abstract:
This case study focuses on the use of 60 Rosemount 708 Wireless Acoustic Transmitters to improve Flare Gas Recovery Unit (FGRU) optimization during the shutdown & maintenance preparation steps of a large turnaround (TA). For the large Fall 2019 TA… shutdown & deinventory was expected to require 10+ straight days of FGRU demand. With high incentives to decrease the amount of downtime for all units, FGRU use optimization was identified as an opportunity. Two months prior to TA, we decided to move forward with an experiment to improve monitoring of the entire flare system using new technology. 60 wireless acoustic/skin temp transmitters were installed at strategic locations on the refinery-wide flare system to provide up to the minute insight into FGRU demand.
Scott opened by introducing the Transformation Manager and how they are driving operational improvements in their 375K barrel/day refinery.
The digital transformation initiative is enterprise-wide in scope with a focus on apply technologies to improve efficiency, lower emissions, and increased utilization. The focus is in three key areas—process control, asset management and business automation.
For the FGRU, the refinery staff recognized an immediate opportunity for improvement. The opportunity was to decrease turnaround time, better coordinate unit shutdowns for 25 units, optimize use of the FGRU compressors over 10+ days and stay within the flare capacity to avoid flaring.
The traditional way to track flare sources were to have a shift manager be responsible for tracking and communicating flare system use. All flare sources were controlled by manual valves and there was limited visibility in the process historian using only flare pressure and FGRU spillback.
Scott explained how Rosemount 708 wireless acoustic transmitters could be deployed to provide much better insight into the source of the flares. For this refinery, individual placement of these acoustic transmitters on pressure safety valves (PSVs) was not economically feasible. These transmitters were installed in strategic locations in lateral headers to capture multiple PSVs to balance the cost and data resolution required.
Trends were setup for each transmitter and deviation alerts specific to locations were created. The alerts are adjusted daily to account for seasonal or process changes.
They shared an example during the turnaround where shift managers were aware of a potential flare source. They sent operators out to troubleshoot a specific flare lateral. With the help of the acoustic transmitters they were able to identify the source of the flare within 15 minutes caused by a valve not fully closing. They also gained FGRU capacity to support other units.
Some of the key learnings with this transformation project was the importance of sensor mounting location. You want to mount in areas of turbulence as close to the potential source as possible such as downstream of pipe elbows, valves and tees. Also install on upstream side of vessels to avoid system dampening. They used stainless steel banding to attach to the pipes.
They set update rates at 60 seconds to preserve battery life, so it is not designed for short flare releases, but rather ones that have longer durations.