Self-heating solid

Flammable solid or self-heating solid materials. 

Now, when a solid chemical of the TD type is placed in the atmosphere maintained at a temperature below T, which is shown in Fig. 2 in Section 1.2, a spatially gradient distribution of temperature is effected in the solid chemical. However, the temperature as a whole does not vary with time in other words, the spatially gradient distribution of temperature effected in the self-heating solid chemical placed in the atmosphere maintained at a temperature below T is stationary. The stationary equation of the thermal explosion theory, Eq. (22), is thus obtained by considering the value of the derivative with regard to the time to be zero in Eq. (20). This approach is called the stationary theory of the thermal explosion [7]. ... 

We see from Eq. (28) that, once the size of a solid chemical of the TD type, placed in the atmosphere under isothermal conditions, is specified in other words, once the values of A H, Aq and E of the exothermic decomposition reaction, in the early stages of the self-heating process, of the solid chemical as well as the values of A and r of the solid chemical are fixed, respectively, the value of S increases with increasing the atmospheric temperature, Ta- There is, however, the upper limit value, or the critical value, of S, i.e., S which S is able to take for a shape of the solid chemical, because there is also the upper limit atmospheric temperature, or the critical temperature, 7)., above which the stationary gradient distribution of temperature in the self-heating solid chemical ceases to be possible, with the result that the temperature of the solid chemical continues to increase acceleratedly to cause the ultimate thermal explosion of the solid chemical. 

In the thermal conduction theory, such a distribution in general is thought to be caused on condition that the rate of thermal conduction in the self-heating solid chemical placed in the atmosphere under isothermal conditions is far less than the rate of heat transfer from the solid chemical through the whole surface to the atmosphere. In other words, this condition is expressed as [/> > A, which is equivalent to that the Biot number takes a large value. 

ORGANIC PEROXIDE TYPE C. liquid, temperature controlled 3126 47 SELF-HEATING SOLID, corrosive, organic, n.o.s. 

Fig. 2. RSST results on various resoles. The three bulk-charged resoles are at approximately 58% solids, 50% solids, and 40% solids. The programmed formaldehyde has no water charged except that contained in the 50% formaldehyde. The 50 and 58% solids resins reach self-heat rates of nearly 600°C/min. The 40% solids resin does not exceed 10 C/min. (Chart courtesy of Borden Chemical and Bill Burleigh.)...

Fig. 3. RSST results on some typical production novolacs. The solids on these materials are 74, 70, and 62%, respectively. Note that the reaction does not become initiated significantly below 70 C and that the high solids system is capable of self-heating rates as high as 5500°C/min under these conditions. (Chart courtesy of Borden Chemical and Bill Burleigh.)...

Boddington and Iqbal [727] have interpreted kinetic data for the slow thermal and photochemical decompositions of Hg, Ag, Na and T1 fulminates with due regard for the physical data available. The reactions are complex some rate studies were complicated by self-heating and the kinetic behaviour of the Na and T1 salts is not described in detail. It was concluded that electron transfer was involved in the decomposition of the ionic solids (i.e. Na+ and Tl+ salts), whereas the rate-controlling process during breakdown of the more covalent compounds (Hg and Ag salts) was probably bond rupture. 

Liquid materials susceptible to self-heating when dispersed on a solid... 

Solid materials susceptible to self-heating in air Activated charcoal Animal feedstuffs Beans Bone meal, bone black Brewing grains, spent Leather scrap... 

A comparison has been made between small scale test results and a field trial at a 17-ton scale for a solid compound [217]. The test results from a very sensitive calorimeter (Thermal Activity Monitor from ThermoMetric, Sweden) were substituted in a model, and the self-heating situation in bulk containers was predicted. The large-scale trial was carried out in a steel rectangular container lined with polyethylene. A control device was used to keep the container at a temperature of 40 to 45°C. Several thermocouples enabled monitoring of the temperature as a function of time in different places in the large container. 

Tharmalingham, S., "The Evaluation of Self-Heating in Bulk Handling of Unstable Solids," in Proceedings of the International Symposium on Runaway Reactions, p. 293, Center for Chemical Process Safety/AIChE, New York, NY (1989). 

Special Studies High Sensitivity Calorimetry A- DESIREEV UNDESIRED dT/dt ATadiab Kinetics, EA, A Sample size 1- 50 ml, pW/g sensitivity Shelf life studies by accelerated aging Combine with low adiabatic to confirm solids low self-heating rate studies... 

Self-heating, due to the stoppage of the alpha particles within the solid, is a well known phenomenon and calculation shows that the energy release from one gram of polonium metal would be about 140 watts. This high energy output affords a useful and absolute method for the rapid determination of polonium in large sources by calorimetry. 

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