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Publication > Issue > Articles
The wet gas sulphuric acid plant - Part 2
Summary
Following the discussion in Part 1 of the gas cleaning section of the wet gas sulphuric acid plant, Leonard J. Friedman and Samantha J. Friedman of Acid Engineering & Consulting continue with a review of the unit operations in the contact section, discussing various equipment designs, materials and the handling of gas stream variables and impurities.Abstract
The aim of this paper is to provide a basic understanding of the design and operating considerations of a wet gas (metallurgical or spent acid regeneration) sulphuric acid plant. A better understanding of the factors that affect equipment design, materials, operation, and the effect of variables should lead to a successful sulphuric acid plant project. In Part 1 we discussed the gas cleaning section. In this concluding part we turn our attention to the contact section.
Off ratio Claus plants
Summary
Operating a Claus unit at a H2S/SO2 ratio higher than 2 can provide many advantages in conditions of variable feed gas composition and flow rates. Lorenzo Micucci, Technologies and R&D Manager at Siirtec Nigi, discusses the merits of operating in High Claus Ratio mode.Abstract
High Claus Ratio (HCR) technology is an upstream technology, which provides an elegant solution combining capital cost savings with high plant flexibility to achieve more than 99.8% sulphur recovery while promoting high plant availability and easier SRU operation. The success of HCR in combined Claus and tail gas (TGTU) applications draws focus to the way Claus plants are operated.There is now more interest in the concept of operating Claus plants off ratio, no matter what tail gas technology is employed.
A region with potential
Summary
Speakers and exhiibitors from around the globe converged on Bahrain in mid-May for British Sulphur Conferences' debut event covering regional issues, the first Sulphur Middle East Conference and Seminar. A powerful series of presentations set the scene for future years of mounting production – and increasing export effort – around the Gulf. Sulphur takes up some of the meeting's stories of potential demand which will help shape the future export planning of Middle Eastern sulphur producers.Abstract
With a total of four days of intensive sulphur eventing in prospect, there was never a possibility that the Sulphur Middle East Conference and Seminar would be some form of mini-event based on the international series of Sulphur conferences. As with the more established of British Sulphur Conferences’ meetings, speakers – all of them international experts in the topics they addressed – arrived at Bahrain’s Ritz- Carlton resort from all points of the compass. Generally speaking, though, the audience was far more locally based (with the addition of several intrepid travellers from further afield keen to absorb the background to a region among the fastest expanding of sulphur producers).
Following the successful inroduction of a pre-conference seminar given by Alberta Sulphur Research (ASRL) at the Sulphur 2003 meeting in Banff, the lead into Sulphur Middle East was, on this occasion, a full and wellattended two-day programme on the science and technology of sulphur production and handling, led by Dr Peter Clark, ASRL’s director of research.
Regenerable SO2 capture makes headway
Summary
The fluid catalytic cracking unit is typically the largest source of air emissions in a refinery. Several options are available to reduce SOx and particulate emissions to meet the latest stringent regulations. Three new technologies are examined in this article: two regenerable SO2 scrubbing processes and a new catalytic SOx reduction additive.Abstract
Requirements to reduce particulate and SO2 emissions in refineries have never been greater. Environmental pressure is heading towards ever lower emission levels, while changing process conditions can lead to higher emission levels requiring control.
In most refineries the flue gas from the regenerator in the fluid catalytic cracking unit (FCCU) represents the greatest single air emission source. It contains significant quantities of catalyst fines and sulphur oxides (SOx).
Particulate (catalyst) emissions from this source vary depending on the number of stages of internal and external cyclones. Although cyclones are effective in collecting the greater constituent of catalyst recirculated in the FCCU regenerator, the attrition of catalyst causes a significant amount of finer catalyst to escape the cyclone system with relative ease. Typically emissions will range from 200 to 650 mg/Nm3.
Sulphur emissions in the form of SOx (SO2 and SO3) from the regenerator vary significantly depending on the feed content and the FCCU design. In the FCCU reactor, 70-95% of the incoming feed sulphur is transferred to the acid gas and product side in the form of H2S.The remaining 5- 30% of the incoming feed sulphur is attached to the coke and is oxidised into SOx, which is emitted with the regenerator flue gas. The sulphur distribution is dependent on the sulphur species contained in the feed, and in particular the amount of thiophenic sulphur.The SO2 content can range from 500-9000 mg/Nm3, whereas SO3 typically varies from to 5-15% of the SO2 content.
Recent trends in the sulphur and sulphuric acid markets
Summary
As an introduction to our statistical supplement, Mike Kitto of the British Sulphur Consultants Division of CRU International Ltd highlights key developments and trends in global production, consumption and trade of sulphur-in-all-forms.Abstract
Sulphur supply remained tight in 2003 and prices continued to firm, maintaining the trend of the previous year. Our revised estimates of brimstone production and consumption in 2002 indicate an apparent supply surplus of just below 2.2 million tonnes, which we believe was a little less than the amount of product that was “involuntarily” stockpiled at a number of remote locations. In 2003, preliminary data suggest a smaller apparent supply surplus of just 1.2 million tonnes. It would appear that there was again an effective supply deficit, as stocks at Alberta gas plants were reportedly drawn down by 460,000 tonnes to fill the supply gap.