Cool stability range

Alkalinity and calcium hardness of circulating water build up to a level determined by allowable operating concentrations. System pH usually plateaus in the stabilization range of pH8 to 9. So long as the Lange-lier Saturation Index of concentrated cooling water can be kept below +2.0 by bleedoff, supplemental acid feed is not required for scale control. 

The stability range of cool flames from n-hexane is shown in Figure 3.26. The succeeding reactions observed by da Silva et d. correspond to auto ignition of the... 

Figure 3.26 Stability range of cool flames depending on feed temperature and system pressure air ratio X = 0.43 fuel, n-heptane [82].

Similar results were obtained for the LC polymer, PM3, when poled at and above Tsn (i.e. in the temperature range corresponding to the theraial stability range of the nematic phase) and slowly cooled to room temperature in the presence of the poling field (rf. Fig. 8). If, however, the specimens were poled at temperature between... 

Ross et al. (1996) reported the results of the 193 nm photolysis of nitroalkanes in the C3-C6 range using time of flight mass spectrometry to detect the products. Both C—N and N—O bond dissociation pathways were observed. Under collision-free conditions, the alkyl radicals formed undergo extensive secondary fragmentation. When photodissociation was performed in a free jet expansion, collisional cooling stabilized the primary products and allowed large radicals such as pentyl and hexyl radicals to be detected. 

Pre-liming. Lime slurry, 0.25% lime on juice (0.250 g of CaO/100 g juice), is added to bring the pH of the mixture into the alkaline range. Insoluble calcium salts are precipitated as finely dispersed coUoids. Calcium carbonate in the form of recycled first carbonation sludge is added to provide coUoid absorption and stabilization. Temperature may be cool (50°C) or hot (80°C) depending on the temperature of the next step, or occasionally on the type of diffusion equipment. Retention time is 15 to 30 min. 

The primary phases all contain impurities. In fact these impurities stabilize the stmctures formed at high temperatures so that decomposition or transformations do not occur during cooling, as occurs with the pure compounds. For example, pure C S exists in at least six polymorphic forms each having a sharply defined temperature range of stability, whereas alite exists in three stabilized forms at room temperature depending on the impurities. Some properties of the more common phases in Portland clinkers are given in Table 2. 

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