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Summary
Renewed demand for phosphates has seen sulphur markets tighten in 2010, but the effect of new sour gas processing capacity on the one hand and phosphate production on the other make the market balance hard to predict over the medium term.Abstract
Global production of sulphur in all forms (SAF) totals about 78 million t/a. Of this, elemental sulphur represents around two thirds, or 50 million t/a, an ever smaller proportion coming from direct mining. Other sources of sulphur (via pyrites or sulphuric acid generated in smelters) amount to about 28 million t/a. As Figure 1 shows, over the past two decades, the proportion of sulphur recovered from oil and gas has steadily increased, and sulphur in all forms production is now dominated by three main sources; elemental sulphur recovered from natural gas processing and oil refining, and sulphuric acid generated by smelting of metals, particularly copper. All of this represents involuntary production, and hence the volume of SAF production is primarily determined by the markets for oil, gas and metals respectively.
Summary
Countries around the world are racing to develop sour gas production in order to make up for falling conventional production, particularly in China, Central Asia and the Arabian Peninsula. Sulphur presents a round-up of recent major sour gas project developments.Abstract
While Canada has taken the lead in developing sour gas production, with sour gas treatment going back as far as 1924, Canadian sour gas production is dropping as wells become exhausted, and the focus of attention is swinging to other regions of the world, especially Arabia, the Caspian Sea and China. Fortunately for western oil and gas majors, the expertise that they developed in producing sour gas in North America has thus become a desirable commodity for the development of dangerous and technically difficult sour gas reserves worldwide, and production from sour gas fields – some of them with H2S contents of more than 30% – is now beginning to expand rapidly worldwide. Needless to say, this is likely to signal a corresponding increase in sulphur production.
Summary
Limits on sulphur content in fuels and stringent environmental regulations have necessitated improved sulphur recovery efficiency in refineries and gas plants around the world. At the same time, there has been a trend toward operation on heavier, increasingly sour feedstocks with higher concentrations of feed contaminants. In the presence of such challenging feeds, proper technologies must be selected and implemented to ensure maximum sulphur recovery efficiencies and high sulphur product quality.Abstract
Recent industry trends focused on producing cleaner air and fuels around the world have generated significant demand for improved sulphur recovery efficiency in both new and existing gas plants and refineries. At the same time, there has been a shift toward heavier, sourer feedstocks as light and sweet feedstocks become increasingly scarce and expensive. Frequently, these feeds contain contaminants such as benzene, toluene, xylene (BTX), heavy hydrocarbons, ammonia, carbon and organic sulphides. Such characteristics present unique operational issues that must be dealt with utilising specific technologies and/or processing conditions.
Destruction of impurities in the reaction furnace is essential to successful operation of the sulphur recovery unit (SRU). Failure to eliminate these contaminants can result in loss of catalyst activity and/or plugging and corrosion of downstream equipment. Ultimately, this can lead to decreased sulphur recovery efficiency, increased maintenance costs, and off-spec sulphur product.
Summary
R.L. Davis, and J.D. Carnes of Davis & Associates Consulting, Inc. examine how a sulphuric acid plant operator implemented plant changes to react to changes in environmental regulation and the marketplace. They examine how technical options were evaluated and a plan was developed to meet their corporate objectives and governmental requirements. An overview of the abatement options considered is provided. After extensive review it was decided that conversion of the single absorption plant to double absorption was the best option for this particular case.Abstract
An ammonium nitrate facility was built in 1942 as part of the war effort. The facility included a single absorption sulphuric acid plant that supplied make-up acid for nitric acid concentration. The facility changed ownership a number of times, and the product mix has been changed. The production of ammonia was shut down and replaced with pipeline ammonia. Nitric acid capacity was increased and is now one of the plant’s products. The nitric and sulphuric acid concentrators have been shut down, and the sulphuric acid plant now supplies regional acid consumers.
Environmental requirements for the facility have changed over the years. Environmental agencies wanted the plant owner to reduce sulphur oxides (SOx) emissions from the sulphuric acid plant and the owner retained Davis & Associates Consulting, Inc. (DAC) to review abatement options in 2003.
Summary
Sulfiran is a liquid-based H2S removal process which directly converts H2S to fine and micronised sulphur as an aqueous wet filter cake. Studies indicate that this sulphur cake, after enrichment, could be used in agriculture as a soil amendment and a plant nutrient, but evidence shows that the mechanical strength of the product after drying is low and it will break down easily to powder. Forming it into a granule could increase its breakage resistance. In this article, F. Vakili, A. Roozbehani, Kh. Forsat, and E. Alaie of Research Institute of Petroleum Industry, National Iranian Oil Company describe laboratory-scale enhancement of sulphur recovered from the Sulfiran process by incorporating appropriate additives and essential macro- and micro-elements and then forming by extrusion, tabletting or granulating to improve its effectiveness in agricultural applications.Abstract
Natural gas obtained from most sources contains hydrogen sulphide (H2S), which not only is a toxic and corrosive gas with irreparable effects on pipelines and environment, but also reduces the calorific value of the natural gas. Therefore it is necessary to remove H2S from gas streams and convert it to a low-risk material such as elemental sulphur. Large amounts of elemental sulphur are recovered annually from H2S abstracted from sour natural gas worldwide. In Iran it amounts approximately to 1.9 million tonnes per annum (almost totally in crystalline form).
The Sulfiran process is a chelated iron-based, liquid redox process for sulphur recovery which has been developed at the Research Institute of Petroleum Industry of Iran (RIPI). Like other redox processes, this is an economic and useful method for recovering sulphur from gas streams containing medium levels of H2S (200 kg – 20 tonnes S/day). It can also be used to complement other gas sweetening processes and in tail gas treatment plants.
Summary
Problem No. 6 Poorly designed or operated SRU catalytic converters. This is the sixth in a series of short articles on the subject of "common problems" with Claus Sulphur Recovery Units (SRUs). In this issue, B. Gene Goar discusses "SRU catalytic converters", based on his wide and varied experience in the design, operation, troubleshooting and remedial problem solving of Claus SRUs.Abstract
As discussed in the last article of this series (SRU reheaters), once the process gas is cooled to the sulphur dewpoint and sulphur is removed in a condenser, it is necessary to reheat the process gas sufficiently before it flows to a Catalytic Converter , such that the process gas exiting the converter is at a temperature which is 20-25°F/11-14°C greater than the outlet gas sulphur dewpoint. If this is not accomplished, then sulphur can deposit on and within the catalyst bed and decrease its efficiency dramatically. In other words, the temperature of the process gas out of a catalytic converter should be 20-25°F/11-14°C higher than the sulphur dewpoint of the process gas stream. The exception to this occurs in the first catalytic converter, where the inlet gas must be reheated sufficiently high to accomplish proper COS and CS2 hydrolysis in the catalyst bed (normally this requires a bed outlet gas temperature of 600-620°F/316-327°C).
Summary
Sulphur's annual survey of recent and planned construction projects for sulphuric acid production.Abstract