Safety of Header and Effluent Disposal Systems
Studies of Chemical and Fluid Processes Important to the Operational Safety of Header and Effluent Disposal Systems in Chemical and Hydrocarbon Process Plant
Tech Area / Field
- CHE-SYN/Basic and Synthetic Chemistry/Chemistry
3 Approved without Funding
Institute of Problems of Chemical Physics, Russia, Moscow reg., Chernogolovka
- European Commission / Joint Research Center / Environmental Institute, Italy, Ispra\nForschungszentrum Rossendorf, Germany, Rossendorf\nHeriot-Watt University, UK, Edinburgh\nUniversity of Nottingham, UK, Nottingham
Project summaryIntroduction and review. The objective of the Project is to study chemical processes (ignition, combustion and detonation) occurring in the main header systems of chemical and hydrocarbon processing plants, development of recommendations for improvement of their operational safety as well as development of environmentally benign technology of thermal oxidation (incineration) for neutralization of liquid and solid wastes.
The Project is a constituent part of the joint European-Russian research Project “HEADER” aimed to improve designs and enhance operational and environmental safety of main headers and effluent disposal systems in chemical and hydrocarbon processing plants. The project will be jointly fulfilled by the Institute of Problems of Chemical Physics (Chernogolovka, Russia), Institute for Systems, Informatics and Safety, Joint Research Centre EC (Ispra, Italy), Nottingham University (UK), Heriot-Watt University (UK), Forschungszentrum Rossendorf e.V., Institute of Safety Research (Germany), and the Frounhoffer Institute for Environmental, Safety and Energy Technology (Germany).
Operation of headers involves the danger associated with ignition of combustible gas mixtures and occurrence of detonation in long pipes. Combustion of combustible vapor and gas in a header initially proceeds as a deflagration (small speed of flame propagation). Then flame accelerates due to turbulence and can accelerate till detonation if the pipe is long enough. Detonation is a very destructive combustion mode propagating with supersonic speed (~ 1800 m/sec) and pressure sometimes rising 100-150 fold. The resulting pulse loading many times exceeds the acceptable value and may cause pipe rupture and significant extension of failure zone due to splinter, heat and shock-wave effects of explosion. A number of serious industry accidents are known when detonation was the result of occasional ignition of gas mixture and clogging of flame-arresters.
The data on combustion/detonation transition in real industry pipes are virtually absent in the literature, particularly those on influence of geometry (bends, ascents and descents, tees, etc.) on the process (predetonation run, concentration dependence, reflection and interference of shock waves, etc.).
Understanding mechanisms of these phenomena is of extremely importance for the risk assessment and development of prevention means.
Considering ever more stringent environmental protection standards on the chemical technology the problem of liquid and sometimes solid (e.g., carbon filters) waste disposal which cannot be recovered and reused is extremely important as well.
The proposed Project is a complex of scientific research and technological developments comprising: theoretical investigation of regularities of ignition of combustible gas mixtures and flame propagation; theoretical and experimental investigation of regularities of combustion/detonation transition and propagation of detonation waves; experimental investigation of regularities of condensed organic substances gasification in the superadiabatic combustion regime; development of methods for environmentally benign disposal of liquid wastes and solid absorbers.
The personnel to be involved in the Project includes experts in the various fields formerly successfully working in development and manufacturing of solid rocket propellants and explosives. Most of the personnel took part in the combustion and explosion research performed in the Institute of Problems of Chemical Physics for many years, in particular, investigations of initiation and development of chemical (chain and thermal) explosions in nuclear and chemical reactors (ISTC project #124-94) and research on application of superadiabatic combustion regimes for gasification of solid combustibles (ISTC project #126-95).
Expected results and their application: The Project will result in:
· Finding regularities of ignition and propagation of turbulent flame in pipes of complicated geometry in a wide range of composition, temperature, and pressure.
· Determination of influence of variable flowrate and pressure waves on flame propagation in a header pipe and stability of incinerator diffusion flare.
· Formulating recommendations on general schemes, parameters, and locations of flame arresters.
· Finding regularities of initiation, propagation, and interference of shock and detonation waves in the pipes containing chemically reactive gases.
· Numerical modeling shock-wave processes in pipes; determination of conditions and design features that would secure minimum pressure rise and lower probability of pipe rupture.
· Assesment of efficiency of various detonation-arresters.
· Finding regularities of gasification of condensed organic substances in the superadiabatic combustion regime.
· Development of thermal oxidation regimes for organic wastes of definite types and giving out recommendations on design of bench-scale unit.
The scientific significance of the Project is finding regularities and critical conditions for propagation and extinction of flame and detonation waves in combustible gas mixtures in pipes of complex geometry as well as regularities of filtrational combustion of organic substances in the superadiabatic regime.
The practical merit of the Project is determined by its ultimate aim, i.e. the development of methods for prevention of accidents caused by initiation and propagation of combustion and detonation waves in headers and development of environmentally benign methods for waste disposal. The results obtained in this project can be of interest for industrial applications as far as design and operation of header systems are concerned. They can be of interest from the point of view of modern procedures for risk assessment developed by the EC Joint Research Center and European DIERS Users Group (EDUG).
Meeting ISTC goals and objectives. The project is entirely correspondent to ISTC aims for it provides scientists and personnel formerly engaged in weapons development an opportunity to conduct research aimed at peaceful activity. Besides it promotes real integration of Russian scientists into the international scientific community and supports basic and applied research and technology development for peaceful purposes.
Scope of activities. The project comprises the following main stages and investigations:
Theoretical investigation of regularities of ignition and flame propagation for combustible gas mixtures. For these purposes it is proposed:
· To analyze existing information about propagation velocity of laminar flame in gas-air mixtures of different inpidual hydrocarbons of homologous families, limits of flame propagation, value of quenching slit and delay times of self-ignition.
· To perform numerical investigation of combustion of gas-air combustible mixtures in pipes, in particular:
– Multidimensional calculations of ignition and propagation of turbulent flame in pipes of complicated geometry (rough walls, bends and branches, local widening and narrowing), in mixtures of inpidual hydrocarbons (methane, ethanol, and others) with air in a wide range of composition, temperature, pressure and taking into account the presence of dispersion phase - condensate and liquid fuel drops.
– Multidimensional calculations of influence of variable flowrate and pressure waves on flame propagation in a header pipe.
· To work out recommendations on general schemes and parameters of flame-arresters as well as on location of flame-arresters and flame and pressure-wave detectors in a header to ensure safe operation of a facility.
· To carry out calculations on stability of thermal oxidizer diffusion flare under conditions of variable flowrate and composition of gas-air mixture.
Experimental and theoretical investigation of regularities of combustion-to-detonation transition and of detonation wave propagation. For these purposes it is proposed:
· To analyze existing information about conditions and physical mechanisms of combustion/detonation transition in gas-air combustible mixtures, about predetonation runs and ways to control transient processes.
· To determine experimentally the kinetic regularities of ignition and detonation capability for real mixtures in header systems.
· To determine experimentally the conditions of combustion/detonation transition in pipes for different ways of initiation for fuel-air mixtures.
· To conduct 2-D numerical modeling of initiation and development of detonation under shock-wave loading, of interference and reflection of shock and detonation waves in pipes of complicated geometry taking into account heat transfer, viscosity, variation in concentration and phase composition of combustible mixture.
· To calculate the pressure profile arising during propagation of shock and detonation waves in pipes of complicated geometry in order to improve design of header structures.
· To carry out numerical investigation of detonation break-down conditions to optimize configuration and dimensions of detonation-arresters.
Development of methods for environmentally benign disposal of liquid and solid wastes in the superadiabatic combustion regime. For these purposes it is proposed:
· To investigate experimentally the regularities of condensed organic substances gasification in the superadiabatic combustion regime.
· To work out regimes for disposal of organic wastes of definite types and propose recommendations for pilot unit design.
Technical approach and methodology. New numerical methods for statistical theory of turbulent combustion developed by the authors of the Project will be used. There are vast kinetic database and application software packages for regular reduction of oxidation schemes of hydrocarbon fuels. Two-dimensional computations of detonation development in gases will employ theoretical models and hydrodynamic codes incorporating the Godunov method on adaptive grids and Inpidual Particles method. Software package will be developed for numerical solution of kinetic equations set with arbitrary number of reversible chemical reactions and species to be incorporated into codes for two-dimensional gas dynamic flows. User-friendly interface for input of initial data and presentation of calculated results will be developed.
The laboratory installations of various configuration will be used during experimental work on determining detonation capability of mixtures and their combustion/detonation transition.
The approaches developed in IPCP while developing new environmentally friendly methods for disposal of industrial and municipal condensed combustible wastes in the superadiabatic combustion regime will be used for development of environmentally benign disposal methods for liquid and solid wastes. The laboratory equipment and bench-scale units will be used for experimental investigation of regularities of condensed organic substances gasification in the superadiabatic combustion regime.
Role of foreign collaborators. The general research program was discussed during the coordination meeting held in Brussels 31.03–1.04.1999 where Dr. Klaus Urban (DG-XII, cooperation with CIS countries) took part as well as the representatives of all the participants of the HEADER project: Dr. S.Morris (JRC EC, Italy), Prof. B.Azzopardi (Nottingham University, UK), Dr. D.Mc.Neil (Herriot-Watt University, UK), Dr. S.Schlter and Dr. A.Dudlick (Fraunhoffer Institute for Environmental, Safety and Energy Technology, Germany), Dr. D. Lucas (Forschungszentrum Rossendorf e.V., Institute of Safety Research, Germany) and Dr. V.Shteinberg (IPCP RAS). Minutes of this meeting were sent to Mr. Nitzold (ISTC). According to the achieved agreements the Project HEADER (Rus) will be performed in close collaboration with the participants of European part of the Project HEADER (Eur) (idea of parallel projects) that suggests permanent exchange of information, discussion of mathematical models, research methods, technical reports, discussion and applications of the results, arrangement of joint symposia and workshops, etc.
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