As many people that work in the Refining and Chemical industry know safety and reliability are two things that are directly related.
In order to increase reliability we need to either eliminate equipment failure modes or at a minimum reduce the probability of failure.
A growing trend that we have seen in the industry to increase reliability of the fuel gas supply to fired equipment is the use of 2 pressure regulators in series which is commonly referred to as a monitor setup. Monitor setups have been used for many years in natural gas pipelines as a form of overpressure protection by containment.
Refiners are finding that this setup can provide the required speed of response for most fired heater applications and provide them with a much higher degree of reliability than a single pressure regulator or pressure control loop.
For fired heaters that are seen as environmental control devices such as thermal oxidizers and incinerators reliability of the fuel gas supply is extremely critical.
Check out the links below for more information on monitor setups including an interactive animation that lets you select different failure modes and see the response of the regulators.
MONITOR ANIMATION WITH FAILURE MODES
PRINCIPLES OF SERIES REGULATOR AND MONITOR REGULATORS (see page 47)