pt q&a
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Q At what plants are you seeing best available burner technology being applied to lower emissions? A Grant Jacobson, Division Manager, Fired Heaters, Becht, gjacobson@becht.com Two segments of owner/operators are investing in new burner technology: u Those experiencing higher energy prices are tending to move in this direction to improve Opex but are also captur- ing improving emissions. v Those who have made carbon-neutral pledges on a timeline are working on plans to meet these commitments. Old and large (high duty) fired equipment is being targeted for these investments to lower emissions to help in these efforts. A Andrew Layton, Principal Consultant and Toshiaki Momoki, Senior Staff Consultant, KBC During the 1990s, or even earlier, environmental regula- tions changed. Regulatory agencies shifted their focus to reducing NOx in emissions as the specifications for NOx in flue gas became more stringent. As a result, advancements in burner design helped improve burner fuel efficiency and turndown and also reduced particulates and carbon mon- oxide (CO). N₂ in the air is the primary source of NOx (organic N₂ in heavier fuels is a secondary source). High flame tempera - tures are favourable to produce NOx from N₂. Reducing the flame temperature is one way to lower NOx, but this action conflicts with minimising particulates and CO in the flue gas, favoured by high flame temperatures. Thus, the burner design must strike a balance. Low NOx burners can be divided into at least two stages of development: u ‘Low’ NOx burners that target ~40-50 vppm NOx at 3% excess O₂ v ‘Ultra low’ NOx burners that target ~10-20 vppm at 3% excess O₂. As the target drops towards 10 vppm NOx and around 50 vppm CO, the design features include air and fuel stag- ing and sometimes flue gas recirculation. Some modern ultra low NOx designs use lean premix with fuel staging without flue gas recirculation. Since the new burners may sometimes be bigger than the existing burners, furnace floor modifications may be nec - essary. The new burners may also have smaller tip holes, which means gas pretreatment to remove liquid droplets and other foulants is often included in the upgrade to con- trol burner fouling. Most furnace systems can and often do use ‘ultra low’ NOx burners. Some petrochemical plants with radiant wall burners use low NOx burners. Several well-known and pro - ficient burner vendors produce these types of burners and have offices worldwide.
Q What efficiency factors are making the removal of mercaptans and acid gas from natural gas more efficient? A Carmella Alfano, Lead Technology Engineer, Carmella. ALFANO@axens.net Géraldine Laborie, Gas Technologies & Sweetening Expert, Geraldine.LABORIE@axens.net, Axens Depending on the type of acid gas that needs to be removed, many factors can play into the efficiency of acid gas removal. High pressure and low temperature can increase the efficiency of both H₂S and mercaptan removal. For CO₂ removal, as kinetics are the factor that needs to be considered, an optimised temperature at high pressure can make the removal more efficient. Another factor that can increase efficiency is the contact time in the absorber. This can be optimised by selecting the appropriate number of trays or type of packing. It is espe- cially important when selectively removing H₂S. The last major factor to consider for increasing acid gas removal efficiency is solvent selection and composition. In the proprietary AdvAmine technology developed by TotalEnergies, IFP Energies nouvelles, and Axens and exclu - sively licenced by Axens, the solvent is selected based on either total acid gas removal (DEA or EnergizedMDEA) or selective removal of H₂S (MDEA). The solvent composi - For CO₂ removal, as kinetics are the factor that needs to be considered, an optimised temperature at high pressure can make the removal more efficient tion is then optimised to maximise the rich loading and minimise the Capex and Opex. When mercaptan removal is also required, total acid gas plus mercaptan removal can be achieved using the proprietary HySWEET technology, which uses a hybrid-based solvent. This technology is developed by TotalEnergies and exclusively licenced by Axens. Operational factors must also be considered: ensuring the proper regeneration of the solvent is imperative, regular solvent sampling to make sure the concentration is correct, and proper solvent filtration to avoid any foaming issues. A Marcello Ferrara, Chairman, ITW Technologies, mfer- rara@itwtechnologies.com, Cristina Ferrara, Senior Process Engineer, ITW Technologies, cferrara@itwtech- nologies.com When running an amine unit, some of the most common ana- lytical parameters that are monitored to check performance include free amine and HSS content on the amine side and
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PTQ Q4 2023
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