Studie av cirkulation och stabilitet i ånga/vattensystem för pannor med naturligt vattencirkel
Examensarbete för masterexamen
In this master thesis the water circulation in a boiler tubewall has been studied and conclusions have been stated about parameters that effect the circulation and the stability. Unsatisfactory or unstabil water circulation is undesirable since it can result in damages on the tubewall. Literature studies have been conducted and calculations have been carried out in computer programmes designed for circulation and stability. A simple circuit, representative of a tubewall in a kraft recovery boiler, has been simulated in the programmes to investigate how different parameters effect the circulation and the stability. The computer programmes basis and theories have been analysed, suggestions on updates of the programmes have been presented and also advice on future work. Of the parameters analysed, there were the cross section area ratio between the reliever and the tubewall and the temperature of incoming feedwater that effected the circulation and stability most. The simulations also showed that the pressure and the heat distribution were of minor importance even though there was a slightly improvement in the stability at higher pressures. A comparison has also been done between different stability criteria as SWH, saturated water head, Ledineggs stability and measurements. The conclusion that has been drawn after measurements and simulations in the stability programme is that SWH can't be used to indicate instability for this specific application.
Kemiteknik , Chemical Engineering