Energy decomposition

Nevertheless, computing methods hare been developed for the estimation of decomposition energies. 

A well-known tool for the estimation of reactivity hazards of organic material is called CHETAH [5]. The method is based on pattern recognition techniques, based on experimental data, in order to infer the decomposition products that maximize the decomposition energy, and then performs thermochemical calculations based on the Benson group increments mentioned above. Thus, the calculations are valid for the gas phase, but this may be a drawback, since in fine chemistry most reactions are performed in the condensed phase. Corrections must be made, but in general they remain small and do not significantly affect the results. 

Decomposition energies are often high and since decomposition products comprise small fragments they are volatile or even gaseous. Consequently, decomposi- 

Therefore, priority must be given to experimental determination of decomposition energies. It is also essential to perform the experiment under conditions that are as close as possible to plant conditions. 

The high energy release accompanying decomposition reactions leads to a high temperature increase if the system is not, or only poorly, cooled. Therefore, a runaway reaction is likely to occur. The consequences can be assessed, using the criteria described in Section 3.3.2. 

---

Decomposition energy The maximum amount of energy that ean be released upon deeomposition. The produet of deeomposition energy and total mass is an important parameter for determining the effeets of a sudden energy release (e.g., in an explosion). 

This compound was found, on investigation of an explosion in a syringe during transfer, to have a decomposition energy equivalent to that of commercial explosives. Slow decomposition, even at room temperature, becomes explosive above 100°C. Shock sensitive. Stable as hydrocarbon solution below 25% concentration. Recommended that this and related compounds be handled only in such solution. See FLUORINATED ORGANOLITHIUM COMPOUND... 

Decomposition energies of some dioxetanes and their dimers [in kcal/mole] (after81))... 

The net incident heat flux at the surface is given by q. An energy conservation for the surface, ignoring any phase change or decomposition energies, gives... 

An example for the design of fail-safe systems for the continuous sulfonation of an aromatic compound has been described [229]. This investigation was undertaken because a thermal explosion had occurred in a pump and circulation line. The total exothermic decomposition energy of the reaction mass is 500 kcal/kg, which is large. 

Decomposition energy the maximum amount of energy which can be released upon decomposition. 

The difficulties in relating the calculated thermodynamic energy of decomposition (—AU) to that occurring in practice are discussed, and values of the experimentally observed energies of decomposition for some characteristic molecular structures are tabulated in comparison with the calculated values. A second table gives the range of decomposition energies which have been measured by DSC for... 

Fig. 7.1 Position of band edges and photodecomposition Fermi energies levels of various non-oxide semiconductors. E(e,d) represents decomposition energy level by electrons, while E(h,d) represents the decomposition energy level for holes vs normal hydrogen electrode (NHE). E(VB) denotes the valence band edge, E(CB) denotes the conduction band edge. E(H2/H20) denotes the reduction potential of water, and (H2O/O2) the oxidation potential of water, both with reference to NHE.

It is also possible to use hydrazine hydrate alone as a monergol owing to its high heat of decomposition. Energy and gaseous products are provided by decomposition induced by permanganates, commonly used in the solid form. 

Before the incident, neither the reaction and decomposition energy potentials nor the triggering conditions of the decomposition were known. Thus, a potentially severe process was entirely under manual control, without provision for an alarm system and emergency measures. A correct assessment of the energies and triggering conditions of the decomposition predicts such an incident, giving the opportunity to design a process that will avoid such incidents. 

Specific heat capacity of the reaction mass c P = 3200 J kg 1 K 1 Decomposition energy of the final reaction mass QJj = 840 kj kg 1 Temperature at which the TMRad of the decomposition is 24 hours ... 

In criticality classes 1 to 3, the energy to be considered is the reaction energy (QL) only, whereas in classes 4 and 5, the energy to be considered is the total energy, that is, the sum of the reaction and decomposition energies ( il rx + Qj,). The temperature increase may represent a threat in itself, but in most cases, it will result in a potential pressure increase. 

An exothermal reaction is to be performed in a 2.5 m3 stirred tank reactor as an isothermal semi-batch process at 80 °C. The specific heat of the reaction is 180kjkg 1, the specific heat capacity of the reaction mass is 1.8 kj kg 1 K 1, and the accumulation is 30%. The reaction is to be at atmospheric pressure and boiling point is 101 °C (MTT). There is a secondary reaction (decomposition) that is uncritical below 105 °C, that is, Tm4 = 105 °C. The decomposition energy is 150kjkg 1 and this decomposition releases 5 liters of a toxic, but not flammable, gas per kg reaction mass, measured at 25 °C and atmospheric pressure. 

---