Sulfur Plant

Typically, refinery sulfur plants consist of an acid gas removal unit, a Claus sulfur recovery unit, a tailgas treatment unit (to achieve sulfur recovery levels >99.99%), and, in some instances, sulfur degasification and finishing processes. The amount of sulfur produced by each refinery will differ based on a number of factors including sulfur content in the feed coupled with the final product slate and final product specifications. This study will focus on the recovery of sulfur in a refinery setting. The processing of sourer crudes combined with increasingly stringent product specifications and the implementation of the IMO's 0.5%-sulfur bunker fuel spec have led to more sulfur being recovered and produced by refineries worldwide.

Although the cost of sulfur removal will be largely detached from factors that are controllable by the refiner, efforts to improve removal efficiency, slash energy use, and uncover more-lucrative and diverse end-uses for elemental sulfur will help to lower removal costs, thus improving overall plant margins. Going forward, refiners will need to ensure that their sulfur plant capacity is adequate to deal with the increased sulfur levels flowing through the refinery due to more stringent transportation fuel specifications and the increased processing of higher sulfur crudes.

How it will benefit you

This study addresses very time issue facing refiners worldwide: decarbonization. Additionally, refinery sulfur plants may not only be asked to remove sulfur compounds from refinery streams but also remove CO₂ simultaneously as governments around the world begin to enact new carbon emissions regulations.

There are several options to remove both CO₂ and SO₂ from refinery flue gases: absorption, adsorption, chemical conversion, cryogenic distillation, electrostatics separation, membrane separation, and so on. Selection of which option is highly dependent on the flue gas characteristics such as CO₂ and SO₂ contents, temperature, pressure, and other components in flue gas. So far, solvent absorption is leading the race. Already, amine absorbents are available that offer the ability to remove both CO₂ and H₂S but amine degradation due to high amine reboiler temperatures can be a concern when removing both H₂S and CO₂. Some Claus processes also offer the ability to simultaneously recover sulfur and CO₂, while other Claus processes significantly reduce a refinery's CO₂ footprint as it eliminates the need to incinerate tailgas. A number of commercial tailgas treatment offerings are noted that remove both sulfur compounds and minimize CO₂ emissions when processing Claus tailgas.

What does it include

The current study, completed in 1Q 2022, begins with updated global sulfur supply and demand fundamentals and prices and new outlets for sulfur to deal with rising sulfur production due to the IMO's 0.5%-sulfur bunker fuel spec and rising processing of medium and heavy sour crudes.

In addition to a comprehensive list of state-of-the-art technologies, recent innovations feature the new offerings by Dow and its UCARSOL solvent line, which can simultaneously remove CO₂ and H₂S from refinery acid gas streams; Fluor's Low Energy Direct Contact Condenser (DCC) for SRU TGTUs where cooling capability is limited; Comprimo/Controls Southeast Inc. new "alternative" sulfur degasification technology called ICOn; TG 203 Claus tailgas hydrogenation catalyst offered by Axens that replaced the older TG 133 catalyst; Euro Support's titania-supported tailgas treatment (TGT) catalyst; Haldor Topsoe's low temperature TK-220 quadralobe extrudates and TK-222 rings CoMo tailgas treating catalysts; Optimized Gas Treating's ProTreat amine-treating process simulator which now includes new hybrid solvents thermodynamics and mass transfer characteristics; AMETEK's 888L air demand analyzer which is a variation of the 888 'top of the pipe' analyzer and designed for users that need to install an air demand analyzer remote from the sample extraction point on a SRU; and Delta Controls Corp. Model HTS ClausTemp Compact Thermocouple and unpurged Model HTV ClausTemp Thermocouple.

The study also includes extensive discussions of plant operations and practices that identify valuable operating experiences and daily trouble-shooting techniques shared by veteran refining professionals around the world. Recent key knowledge include a case study from CS Combustion Solutions for retrofitting the thermal stage of a SRU and a method of controlling the main air blower of the Claus unit within the SRU to boost the SRU's overall energy efficiency while also reducing capital and operating costs from Howden.

To plot future sulfur plant directions, the study gathers and reviews the latest patent applications and research papers regarding refinery sulfur plant technology, including simultaneous removal of CO₂ and sulfur compounds in acid gas removal units; novel absorbent materials for acid gas removal; Claus processes with multiple reactors and/or reaction zones; tailgas treating processes for improving the rate of sulfur recovery; novel catalysts for both Claus and tailgas treating applications; sulfur degasification improvements; and more.

Keywords: SRU, acid gas removal, AGR, Claus unit, tailgas treating, TGT, SO_X, desulfurization, CO₂, COS, clean fuels specification, H₂S, ultra-low sulfur, ULSD, ULSG, clean fuels, elemental sulfur, direct oxidation, amine scrubbing, amine solvent, advanced process control, acid gas corrosion, foaming, amine loss, fuel gas sweetening, ammonia destruction, BTX destruction, sour crude, sub dew-point Claus, oxygen-enriched Claus, sulfur degasification, sulfur finishing, sulfur granulation, analyzers, instrumentation, sour water stripper gas

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