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Wave goodbye to dirty sulphur

Summary

An economic and efficient methodology to address the problem of contaminated sulphur at production plants, shipping terminals and sulphuric acid plants throughout the world has been developed by The Brimrock Group, Inc. Commercialisation of the new off-the-shelf technology to remelt contaminated sulphur, process it to remove contaminants, and send the purified sulphur back into the supply chain is slated for early 2008.

Abstract

Each year, millions of tonnes of bulk elemental sulphur are traded world wide, yet its elemental purity is among the highest of any material in commerce. Consumers rely on purity specifications which minimise their risk and optimise operations as their all-important feedstock is produced, formed, transported long distances and handled repeatedly en route to their stockpile.

The internationally accepted purity specification is 99.90% or higher, allowing only 500 ppmw (0.05%) ash and 250 ppmw (0.025%) carbon, in addition to limits on H2S (<10 ppmw), water (0.5 – 1.5% wt-%), acidity (0.020% wt-%), selenium (<1 ppmw), tellurium (<1 ppmw) and arsenic (<0.25 ppmw).

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The fuel gas challenge

Summary

The results of a five year programme at sulphur producing gas plants in Canada and the USA have shown tremendous opportunity for energy conservation and emission control. John Sames of Sulphur Experts discusses how the application of Integrated Energy Audit™ techniques with subsequent process optimisation, benchmarking and new technology implementation, improves profits while reducing greenhouse gases.

Abstract

High energy process and supply constraints have made it abundantly clear that energy consumption associated with the processing of raw natural gas and refining of crude oil has a significant economic value that should be properly accounted for. It has also highlighted the need to identify opportunities to conserve some of this fuel and at the same time realise reductions in greenhouse gas (GHG) emissions from these facilities.

The issue of fuel gas efficiency has not been of paramount importance to many operators in the upstream oil and gas processing (UOG) industry because it is seldom included as a line-item cost in their operating budgets. Often the value of this gas was neglected in accounting procedures and indeed it was often not metered.

Fuel gas consumption has in many cases been included in the category of “process shrinkage” and has been accep­ted as such. In reality, all fuel gas consumed is a direct subtraction from potential sales and therefore fuel gas saved translates directly to an improvement in the bottom line.

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Sulphur from tricky feedstocks

Summary

The feedstocks in any sulphur recovery unit have to be evaluated to ensure the design will provide robust, reliable operation. A well-designed burner and reaction furnace, which promotes good mixing of the reactants, is essential for complete destruction of undesirable feed contaminants. This article discusses some of the many strategies used when faced with difficult feedstock scenarios.

Abstract

The sour gases produced in the amine treatment of natural gas and in the treatment of gas associated with oil production are often lean in H2S and contain impurities such as BTX (benzene, toluene, xylene), mercaptans, and hydrocarbons.

In many cases, offgases containing disulphides and additional feedstocks rich in SO2 also have to be treated in sulphur recovery units to satisfy the requirements of the environmental authorities.

A peculiarity of these treatments is the frequent fluctuations of the composition of the feedstock and in particular of the H2S content, with significant impact on the operating stability of sulphur recovery units.

The concentration of H2S and the presence of certain impurities in the feedstocks to Claus units play a crucial role in the selection of the appropriate plant configuration.

An important parameter to be considered during the combustion of the acid gas in the Claus burner is the flame temperature, which has to be high enough to ensure flame stability and to allow the complete combustion of the hydrocarbon based compounds sent to the burner.

The hydrocarbons contained in the acid gas that are not completely converted to CO and CO2 in the Claus burner may crack in the Claus catalytic reactors forming soot, which may plug the catalyst in a short time.

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Refiners face sulphur challenge

Summary

Tightening environmental regulations and increasing sulphur content of feedstocks are pressuring refiners on both sides of the supply/demand equation. The result can be seen in the proliferation of treatment technologies.

Abstract

Refiners are caught in something of a bind at present, with environmental legislation of increasing stringency on the one hand requiring use of renewable feedstocks and ever-lower sulphur limits, and on the other hand increasing quantities of sulphur in the raw feeds to the refineries, as the world’s supply of sweet crude diminishes.

The sulphur content of crude oils continues to increase. Globally the average sulphur content of crude oil is about 1.6% by weight, but in parts of the Arabian Gulf, where new production is concentrated, this rises to 2.1% in Kuwait, 2.0% in Iran, 2.5% in Iraq, and 2.7% in Qatar. And in Canada, extraction of heavy bituminous oil sands with a sulphur content of 4-5% is now ramping up rapidly. Industry experts believe that global production of light, sweet crude peaked somewhere between 2001-2004, and is now in decline. The price of sweet crudes has increased accordingly, and the incentive to process more sour crude has therefore likewise increased.

In Europe, the prospect of growing crude imports from Russia will mean new pipeline supply routes and quality issues will present a new challenge to some refiners. The EU’s emerging CO2 emissions trading scheme will throw up another cost variable. Meanwhile, on the demand side, growing gasoline demand in the US and booming product demand in Asia are also new variables to be grappled with.

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Smelters hold the cards

Summary

A look at the trends shaping the market for sulphuric acid worldwide.

Abstract

The production of sulphuric acid accounts for around 90% of world sulphur-in-all-forms use, most of which is produced on-site for captive use. However, an alternative source of sulphuric acid has gained much greater prominence in recent years, namely the acid produced on an involuntary basis as a by-product of base metals smelting. (The Global Outlook for Sulphuric Acid 2006-2016, Joanne Peacock, British Sulphur Consultants. Paper presented at Sulphur 2007, British Sulphur Events, Montreal [October 2007].)

IFA estimates that world production of sulphuric acid totalled 199 million tonnes H2SO4 in 2007, equating to an increase of more than 4% over 2006. The additional 8 million tonnes came from higher output from sulphur burning units and smelters. Acid from brimstone comprised an estimated 62% of this total, while acid produced from pyrites accounted for 8%. Global production of smelter acid totalled 56 million tonnes H2SO4, representing 26% of total new acid production. This represented an increase of 60% over production ten years earlier, equivalent to nearly 20 million tonnes. This was attributed to smelters’ high operating rates supported by strong demand for copper and nickel, in combination with new smelter capacity and rising SO2 capture. (Fig. 1)

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Sulphur recovery projects

Summary

Sulphur's survey of recent, current and future construction projects maps the developing shape of brimstone production from fuel processing plants worldwide.

Abstract

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