PTQ Q4 2023 Issue

H₂S/mercaptans content on the gas side. The absorber delta P, among the others, will dictate unit capacity. A common way to address reduced efficiency is to mea - sure HSS on the circulating amine, increase amine make- up, and/or perform amine reclamation whenever the HSS content exceeds defined values. Normally, a 1.5 wt% HSS content is targeted in the circulating amine. While the bespoke approach increases operating costs (such as amine, reclamation, and disposal costs), it will not address HSS/amine degradation products deposition into the unit. Reclamation and/or amine make-up increase will affect the circulating amine but cannot address any fouling inside the equipment, with specific reference to the absorber/regenerator. HSS/amine degradation products will deposit inside the unit during amine circulation and accumulate in tower internals. Trays/packing fouling will dramatically reduce tower efficiency and acid gas removal. Trays/packing fouling will also have a major impact on foaming because the gas will preferentially find its way along the not-fouled portion of the tower internals, thereby increas - ing its velocity. It is well known that foam will expand upon A common way to address reduced efficiency is to measure HSS on the circulating amine, increase amine make-up, and/or perform amine reclamation whenever the HSS content exceeds defined values increasing gas velocity, not to mention that the fouling itself and the solids (HSS/amine degradation products) will con - tribute to stabilising the foam. Foam formation will further reduce gas removal efficiency and lead to capacity reduction. We indeed have seen many cases wherein increased antifoam injection did not bring any help to foam mitiga - tion. Therefore, lower acid gas removal efficiency must be addressed differently by keeping in mind that the conven - tional approach is costly and will lead to a capacity reduction. By applying ITW Online Cleaning technology, the entire amine unit can be cleaned in 24 hours on a feed-out/feed- in basis. This is, therefore, a powerful optimisation tool for the entire amine unit, which can resume production after 24 hours under clean conditions, getting the value of enhanced acid gas removal efficiency and reduced energy consump - tion (the reboiler and the lean/rich exchangers will also be included in the cleaning). Q What strategies can be considered to integrate ethyl- ene plant furnaces and gas turbines to improve the facil- ity’s energy balance and efficiency? A Berthold Otzisk, Senior Product Manager – Process Chemicals, Kurita Europe GmbH, Berthold.otzisk@kurita- water.com In steam cracking furnaces, product yields are reduced

when coke deposits inside radiant coils are formed. This has a direct impact on the energy balance in the down - stream section because efficiency losses and side reactions like CO or CO₂ formation can then be observed. Glass ceramic coatings on the furnace tube surface reduce catalytic coke by forming a very thin layer of diffu - sion barrier. This improves the on-stream time of a furnace before decoking is required. The use of sulphiding agents is an alternative. Sulphiding agents with DMDS or Kurita Cut-Coke are well-known, cost-effective, and proven coke inhibition technologies. Typical dosing rates are 20-100 ppm sulphiding agent injected into the dilution steam dur - ing normal operation conditions. Kurita Cut-Coke is a poly - sulphide with a high flash point of 100°C and a significantly lower, more pleasant odour compared to DMDS. Ethane, LPG, and unconverted oil (UCO) from hydro - crackers require continuous treatment with the sulphiding agent. Naphtha feed from the crude distillation unit already contains sulphur, so a continuous coke inhibition treatment is not needed. If all cracking furnaces (including naphtha cracking furnaces) are treated with the sulphiding agent for 2-4 hours after decoking operation, longer runtimes and lower CO and CO₂ concentrations in the downstream section can be achieved with this pretreatment. This has a direct impact on a better energy balance with lower energy costs. Gas compressor fouling may require an unscheduled shutdown. A fouled compressor operates at higher than desired suction pressure to maintain the desired discharge pressure with a loss in efficiency. In most cases, thermal degradation to coke, free radical polymerisation, and Diels- Alder condensation are the causes of fouling. Wash oil, wash water, and powerful antifoulant programmes with dispersants and fouling inhibitor components avoid or sig - nificantly reduce fouling. This ensures lower energy costs and higher product yields. A Frederico Epstein, Study Manager, HSB Solomon Associates LLC, frederico.epstein@solomoninsight.com Ethylene crackers with gas turbine (GT) integration are among the most energy-efficient in the business. Despite that, an analysis of the feasibility of that type of integra - tion will not always show the option as economically viable, depending on different factors. The primary factor affecting the feasibility of those proj - ects is the availability of electrical power at low costs. Generally, the GT/cracker integration is not present in locations where reliable electrical power is available at a reasonable cost. In contrast, the need for reliable internal power generation in a market with high energy costs will drive the feasibility of those projects. Beyond decisions regarding the availability of power and energy costs, an important consideration is the moment of the investment decision in the asset’s life. Despite a considerable array of energy efficiency improve - ments available to operators, preheat systems for boiler feed water and combustion air, integrated gas turbine or cogeneration units, or waste heat boilers (for example), installation of these capital-intensive options within the

PTQ Q4 2023