TECH TALK
Greening Process Equipment One Device at a Time
The quest for emission reduction has reached a fevered pitch . Driven by corporate goals for environmental improvements and backed by a host of recent government standards targeting greenhouse gas emission reductions , plant personnel are faced with a pressing mandate to reduce , and ideally eliminate , releases to the atmosphere . But where to begin ?
To start , it is important to consider the variety of ways available to cut emissions and meet corporate and regulatory goals . By describing the various types of emissions , and providing several different solutions to target and reduce those emissions , it becomes evident that the implementation of these technologies can be very successful .
By Marcelo Dultra , Dan Myers , and Emily Thomas – Emerson
A Changing Environment
The global focus on greenhouse gas emission reduction has spurred governmental agencies around the world to address the issue . Each revision of the Environmental Protection Agency regulations mandates ever tighter limits on a wide variety of targeted chemicals , and many investors and stakeholders are now actively demanding that companies engage in environmental improvements and publicly show their progress . The calls have been so great that the Security and Exchange Commission is creating reporting guidelines so companies can provide consistent and accurate accounts of their environmental , social , and governance programs — alongside their standard financial reports .
Beyond the obvious benefits to the environment and a company ’ s public image , emission reduction also makes financial sense . Every bit of product and raw material that escapes the plant is money thrown away . Add in the cost of wasted energy used in production , plus the time and effort required for processing , and the losses can be staggering .
Clearly , there is strong incentive for a company to reduce these emissions , but until recently the cost of these projects could be overwhelming . Fortunately , valve vendors have introduced a host of new solutions , each of which offer significant emission reductions at a competitive price .
Understanding Emission Sources
The first step to achieving emission goals is understanding the problem . There are two types of emissions that occur in an operating plant , and each has its own challenges and solutions , see Figure 1 .
Figure 1 : Emissions generally fall into one of two types : fugitive emission from unintentional leaks ( left ) and intentionally vented emissions ( right ).
Fugitive emissions are unintentional and undesired leaks that discharge gases or vapors from pressure-containing equipment . There are a wide variety of fugitive emissions , but the more common types are valve packing leaks , relief valve seat leaks , pump seal leaks , and flange leaks .
The other type of emissions is vented emissions . These emissions result from intentional releases of gases or vapor from equipment such as relief valves and pressure vents , and from pneumatic equipment which uses natural gas instead of air as the actuating media , with the latter type of installations common at well sites because instrument air is often not readily available .
Each of these types of emissions can be dramatically reduced by utilizing a variety of solutions , as described below .
Solutions for Fugitive Emission Reduction
Valve packings have a difficult task to perform . They must contain the process
Figure 2 : The picture on the left shows a typical rising stem control valve with standard packing . More modern packing designs , such as the Fisher ENVIRO-SEAL TM shown on the right , employ compressed Belleville or other special springs to maintain pressure on the packing rings . This ensures fugitive emissions are limited to 50 ppm or less , even as the rings wear .
Figure 3 : This graph illustrates a typical relief valve leakage event . After the first blow down , the valve does not shut completely . Leakage is indicated by elevated acoustic noise ( blue line ) and an elevated temperature ( green line ).
18 Valve World Americas | September 2022 • www . valve-world-americas . net