A new European regulation, aimed at reducing the air pollution caused by diesel motor emissions, stipulates a significant reduction in the amount of sulphur present in diesel oil. The sulphur residual values in the diesel oil distributed in the European market will need to be less than 30 mg/l of sulphur from 2005 and less than 10 mg/l of sulphur after 2009. Similar regulations, if not already in place, will be implemented to other worldwide markets.
The new regulation will have significant environmental benefit, taking into account that diesel motors power around 30% of cars and nearly 100% of heavy transport in Europe. Many oil companies have already started to update their plants in order to reduce the sulphur content in their diesel oil production.
In order to achieve these levels of desulphurisation, the plants require a highly specialised multipoint temperature system to control the process. Endress+Hauser has recently supplied such systems for two big reactors installed at the largest Italian refinery plant - AGIP Sannazzaro. Three other AGIP refineries are also evaluating the same system.
The specific requirement of the multipoint temperature system - the technical process was developed by Haldor Topsoe - at AGIP is to create between 12-18 temperature points in 2/3 sections of the reactor, with limited process connections. This is due to the process having high pressure/temperature with dangerous emissions (sulphur, SOx). Too many process fittings on the reactors could cause unnecessary risks and complications. The system monitors the temperature at the catalyst bed area, in order to prevent damage to the catalyst, as well as to effectively control the process. The catalyst area is the heart of the plant and replacement/repair costs would be significant, not to mention the consequences of downtime.
The multipoint temperature system adopted by Endress+Hauser is referred to as the 'Octopus Temperature System', due to the many tentacles - bent stainless steel (AISI 321) pipe thermowells - for housing the thermocouple inserts that are attached to the head. The piping is attached to a mechanical structure, which is mounted to hooking plates that are welded onto the reactor's inner wall. The mechanical structure is very robust in order to resist the internal stresses and strains caused by the multiple effects of weight (catalyst), temperature and pressure.
The system is specially designed to allow the thermocouples to be installed/removed during the process operation. The system's head includes a safety control system to detect leakage (due to a damaged thermowell) - two pressure transmitters detect an increase in pressure within the head's chamber. All the systems are currently PED (Pressure European Directive) certified and all relevant tests are carried out in order to obtain this certification - such as dye and liquid penetrant and pressure tests, as well as X-rays. Should it be necessary, certifications of other countries' standards can also be adopted.
For more information contact Grant Joyce, Endress+Hauser, 011 262 8000, [email protected], www.za.endress.com
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