Refining clean fuels is the biggest challenge faced by refineries across the globe. When we say clean fuels we are referring to reduced sulphur content in the fuel.
Traditionally, all fossil fuels have sulphur content which is desulphurised using various refining processes like hydrotreating and hydrocracking. As everyone is aware that the combustion of high sulphur results in ozone depletion which has devastating effects on the environment and health. The industrial community the world over has emphasized on reducing green house emissions.
Especially in the transportation sector they intended to curb large scale green house emissions by implementing emission standards. These emission standards adopted by various countries mandated that the fuel combustion equipment in vehicles to undergo drastic design changes and also the fuel from refineries be clean.
The current emission standard EURO VI or equivalent requires 10 ppm sulphur content which is an even greater challenge for the global refineries.
The challenge is that the process of reducing sulphur involves high pressure and high temperature. It is further compounded by intermixing of fluids in gasketed heat exchangers causing sulphur slippage in the refining process.
This requirement for clean fuels compels the refineries to revamp their existing hydro cracker and hydro treating units or set up new modules which enable them to produce fuel with 10 ppm sulphur content.
To overcome this challenge the refineries need a unique heat exchanger which can operate under high temperature and high pressure. At the same time the heat exchanger should not allow, intermixing of fluids and also it should provide ease of maintenance.
A study was undertaken by TEMA under the aegis of Mr. Haresh K. Sippy, Managing Director to address this issue which resulted in an innovative design to overcome the challenges faced by the refineries.
This challenge can be overcome by the refining world by turning to essentially a highly effective SCREW PLUG HEAT EXCHANGER designed and manufactured by TEMA.
Breech Lock or Screw Plug Exchangers are basically U-tube exchangers. The channel side operates at high temperature and pressure and it has a threaded end closure. In some designs, the shell side may also be at high pressure. The tube bundle is removable without having to dismantle the channel or disconnect the nozzles from the pipeline. Thus screw plug exchangers help to reduce fabrication cost, moreover its design is such that it enables quick and effortless in-service maintenance.
The major problem encountered with the use of such end closures are 1) Jamming of the threaded plug, due to “Bell Mouthing” and 2) leakage through the tubesheet gasket.
These issues are successfully resolved the modified Screw Plug Heat Exchanger design by TEMA.
There are around 150 TEMA-make Screw Plug Heat Exchangers in service all around the world. With the emphasis on clean fuels and adherence to EURO VI or equivalent emission standards around the globe this new approach to refining clean fuels using Screw Plug Heat Exchanger is the only way out.
A paper titled “An improved design of threaded closures for Screw Plug (Breech Lock) Heat Exchangers” was presented on this by Mr. Haresh K. Sippy at the 50th ASME Pressure Vessels and Piping Conference held at Vancouver, Canada in July 2016 which was well received.
- The paper presented will be made available online for purchase by ASME end of December 2016 on http://proceedings.asmedigitalcollection.asme.org/proceedingbrowse.aspx#Year
- The link will be updated when the article is published and available online for purchase
Copyright © 2020 Haresh Sippy
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