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High viscosity emergency relief systems.


The objective of this project is the study of the characteristics of high viscosity two phase reactive fluids in order to develop and validate on the industrial scale guidelines for the adequate design of relief vents and disposal systems. The use of emergency relief venting remains one of the most commonly used methods to protect against the consequences of runaway reactions and other sources of over pressurisation in the process industries. Existing methodologies for the design of such systems were developed for fluids of low viscosity and to date little work has been carried out to develop and validate these for the industrially important class of reactions involving high viscosity fluids which include many polymerisation processes for the manufacture of bulk chemicals as well as fine chemicals such as resins and paints.
The project includes a systematic experimental study of the influence of high viscosity on the degree of level swell in reactors and on flow characteristics, e.g. mass flow and pressure drop, through orifices and pipes coupled with the development of theoretical models to describe the basic physical phenomena. Experiments will be carried out using 20 and 60 cm diameter bubble columns under conditions typical of those occurring during relief scenarios together with measurements of level swell in a commercial reactor involving high viscosity fluids to develop vapour/liquid disengagement models to predict the onset of two-phase flow. Pilot plant tests at the 13 1, 801, and 3001 scale will be used to evaluate the influence of high viscosity on the venting and disposal process including the design of quenching systems using model fluids. Further venting and disposal experiments at the 801 scale will be carried out using a typical industrial reaction involving high viscosity fluids to include the reactive state in the study.
The understanding gained of the basic underlying processes involved will be used to develop guidelines for the adequate design of emergency relief systems for high viscosity reactive fluids. These will then be validated by venting and disposal tests involving both non-reactive and reactive systems on the 10m3 scale. Laboratory experiments will be used to characterise the chosen industrial process and also to investigate the applicability of direct vent area to volume scaling methods for high viscosity systems and to develop guidelines for their use.
The research in the project will remove many of the current assumptions present in the sizing of relief vents for high viscosity fluids. These assumptions, which by necessity are conservative in nature, result in the installation of large vents to ensure that reactors are not subjected over pressures and subsequently rupture leading to a catastrophic loss of containment. Oversized relief vents lead to high fluid flows which subsequently require extensive disposal systems resulting in wasted capital and maintenance costs. The development of validated methodologies ranging from simple direct scaling, for the cases where complete characterisation of the runaway reaction is not justified, to detailed models using vapour/liquid disengagement will result in reduced costs and improved safety for a wide sector of the process industries.

Funding Scheme

CSC - Cost-sharing contracts


August-thyssen-strasse 1
59067 Hamm

Participants (3)

3,Osterfelder Strasse 3
46047 Oberhausen
Shell International Oil Products BV
1030 BN Amsterdam
Universität Dortmund

44221 Dortmund