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Publication > Issue > Articles

Faster alert times to excessive gas ­temperatures

Summary

A new infrared thermometer that measures both the gas and refractory temperatures simultaneously has been developed. The dual capability provides near instant warning of gas temperature surges in the reaction furnace while continuously monitoring the refractory temperature. Earnie Emery and K. Irani of Mikron/E2T introduce the Pulsar III.

Abstract

With the advent of oxygen enrichment, temperature control of the reaction furnace in the SRU has taken on a new importance. Operating much closer to the refractory temperature limits requires not only accurate temperature but early warning of excessive gas temperatures. The motivation for the in­jection of oxygen into the reaction furnace is clearly shown in Fig. 1.

The industry standard infrared thermometer, the E2T Pulsar II, measures the total temperature in the reactor and is an excellent process indicator for it is unaffected by feedstock, mixture ratio or gas composition. However this does not tell the operator the gas temperature. Nor does the typical double thermal well, gas purged thermocouple report the true gas temperature.

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Improved refinery ­alkylation

Summary

The CDAlky process, with its unique reactor design for sulphuric-acid-catalysed alkylation ­technology, provides refiners with a cost effective option for replacement of existing contactors, expansions, or addition of new grassroots capacity. Kerry L. Rock and Scott Shorey of CDTECH presented the new design at the 9th Annual ERTC Meeting in Prague in November 2004.

Abstract

In California and in countries adopting the European gasoline reformulation scheme, olefins and aromatics in the gasoline pool are being de­creased to reduce vehicle exhaust emis­sions. The high octane in these components must be replaced to main­tain gasoline quality. Europe, the US and Canada are leading the world in reduction of gasoline sulphur, also to reduce emissions. The main source of sulphur is the FCC gasoline, which contains significant, high-octane ole­fins. Removal of the sulphur to meet 10 ppm pool specification also saturates olefins, resulting in additional octane loss. Efforts to remove MTBE from US gasoline will ultimately re­duce the volume of the gasoline pool, thus decreasing gasoline supply even if the oxygen content is replaced by ethanol.

Alkylate will play a key role in the move towards clean gasoline. It contains no olefins, little aromatics, and very little sulphur. As shown in Fig. 1, only MTBE has lower ozone yield.

Next to MTBE, alkylate has the highest octane of normal refinery gasoline pool components (Table 1). Ceasing production of MTBE frees up isobutylene to use as feed to the alkylation unit. Since most alkylation units are already working at or near capacity, expansion may be required to process the additional olefin feed.

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ASRL Review

Summary

Surface block storage of elemental sulphur: a simple strategy to prevent all emissions -- Peter Clark describes work at Alberta Sulphur Research which examines possible emissions from sulphur stored in block in hot climates and elsewhere. It is a classic illustration of how research into esoteric and apparently unimportant issues opens the door to simple solutions to practical problems.

Abstract

Who would think that evaporation of solid sulphur could be a source of emissions from a sulphur block? In the author’s experience, sulphur blocks seem to be rather permanent structures, and – perhaps to the chagrin of those who would like to see their block disappear – they stubbornly silhouette the skyline framed against the spires of steel of the average gas processing plant.

However, it has been suggested that people who live in hot climates may actually see their sulphur blocks evaporate before their eyes since surface temperatures can reach very high values in the midday sun. Posed with this possibility, a first reaction might be to dismiss the idea of an evaporating block as so much science fiction. However, sublimation of sulphur is certainly not “cold fusion”, so we at ASRL decided to take a closer look at the possibility and carried out a programme of research to understand the issues.

As the reader will learn, this is a beautiful example of how exposure of ASRL to problems that certainly do not exist in Alberta has lead to a simple way to cut emissions that can arise from sulphur blocking anywhere in the world – including Alberta.

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Hydrogen optimisation for refineries

Summary

An improved methodology for hydrogen optimisation has been developed that overcomes the limitations of previous methods such as hydrogen pinch, which suffered from inaccuracies due to its binary structure, and the inability to consider hydrogen sulphide or pressure impacts. Dennis A. Vauk of Air Liquide America and Dr Nick Hallale of AspenTech UK discuss the methodology.

Abstract

More stringent clean fuels regulations are being implemented in many parts of the world including Europe and the USA, and these regulations are going to become more and more strict as time progresses. Major oil refinery revamps are necessary in order to meet the specifications set out in the legislation, especially the requirements to reduce sulphur content, and one of the consequences is that hydrogen demand is increasing significantly.

When studying the best way to meet these new hydrogen requirements, the influence of hydrogen quan­­tity, purity, pressure (and hence compression), routing through the re­finery and cost must all be considered by refiners. There are also important considerations regarding the fuel gas system – especially, the amount of fuel gas and its hydrogen content – that play a role in the profitability of the refinery.

In 2001, Air Liquide and Aspen Tech formed an alliance, PRO-EN™ Services, to provide hydrogen optimisation services to refining companies. Since forming the alliance, the two companies have performed over fourteen hydrogen optimisation studies for refineries in North America and Western Europe.

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Using polymers in ­sulphuric acid service

Summary

Polymers have been used successfully in sulphuric acid corrosion protection systems for decades. Mahmoud Salehi and Dr Andreas Hopp of Steuler Industriewerke provide a brief overview of the corrosion protection materials used in sulphuric acid plants.

Abstract

The concrete and steel components in plants producing or handling sulphuric acid are exposed to highly aggressive corrosive stresses. Consequently, custom­ised corrosion protection systems must be designed and implemented to achieve long service life of the components and to en­sure that the plant and production fac­ilities are suitably protected.

Elevated and/or fluctuating temperatures intensify the corrosive effect of sulphuric acid. In addition, plant components are frequently exposed to mechanical stresses, e.g. pressure loads or abrasive stresses.

Organic polymers have been used with great success in corrosion protection systems for these components for many years. Nowadays a very diverse range of materials is available. The most suitable and economical materials for individual components are sel­ected according to the chemical, thermal and mechanical stresses that they are exposed to.

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