Hazard analysis heat transfer

Critical process safeguards as alarms and trips. A Process Hazards Analysis may have questioned the lack of a loss of heat transfer fluid flow alarm and burner firing shutdown for a flow loss condition. 

Identify hazardous chemicals from databases as discussed in Section 16.4.4 and from local legal regulations. Identify the potential for hazards from the checklist for reactivity (in Section 16.4.4) and from HAZOP-type studies or fault-tree analysis (Crowl and Louvar, 1990). In HAZOP studies, use checklist key words as triggers to systematically analyze the impact of changes to flow rate, temperature, pressure, composition, level, viscosity, heat transfer, reaction, and conditions and the potential for barrier failure and startup and shutdown to cause hazards. 

The analysis of the evolution and/or destruction of hydrocarbons during the incineration of MSW and hazardous waste involves heat transfer, mass transfer, and reaction kinetics. The key phenomena include the flashing of liquid hydrocarbons the vaporization, desorption, and stripping of hydrocarbons the pyrolysis and charring of hydrocarbons and the oxidation of char. To a certain extent these processes occur in parallel (steps 2, 3,4, and 5) and are common to most thermal treatment processes. 

Heat Transfer and Hydraulics 6 Systems Analysis 7 Hazards Analysis... 

The parameter p (= 7(5 ) in gas-liquid sy.stems plays the same role as V/Aex in catalytic reactions. This parameter amounts to 10-40 for a gas and liquid in film contact, and increases to lO -lO" for gas bubbles dispersed in a liquid. If the Hatta number (see section 5.4.3) is low (below I) this indicates a slow reaction, and high values of p (e.g. bubble columns) should be chosen. For instantaneous reactions Ha > 100, enhancement factor E = 10-50) a low p should be selected with a high degree of gas-phase turbulence. The sulphonation of aromatics with gaseous SO3 is an instantaneous reaction and is controlled by gas-phase mass transfer. In commercial thin-film sulphonators, the liquid reactant flows down as a thin film (low p) in contact with a highly turbulent gas stream (high ka). A thin-film reactor was chosen instead of a liquid droplet system due to the desire to remove heat generated in the liquid phase as a result of the exothermic reaction. Similar considerations are valid for liquid-liquid systems. Sometimes, practical considerations prevail over the decisions dictated from a transport-reaction analysis. Corrosive liquids should always be in the dispersed phase to reduce contact with the reactor walls. Hazardous liquids are usually dispensed to reduce their hold-up, i.e. their inventory inside the reactor. 

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