Available heat

Table 1. Commercially Available Heat-Transfer Fluids...

Includes power from recovery of available heat in seed system. This number is a percentage. 

Polymerization in Hquid monomer was pioneered by RexaH Dmg and Chemical and Phillips Petroleum (United States). In the RexaH process, Hquid propylene is polymerized in a stirred reactor to form a polymer slurry. This suspension is transferred to a cyclone to separate the polymer from gaseous monomer under atmospheric pressure. The gaseous monomer is then compressed, condensed, and recycled to the polymerizer (123). In the Phillips process, polymerization occurs in loop reactors, increasing the ratio of available heat-transfer surface to reactor volume (124). In both of these processes, high catalyst residues necessitate post-reactor treatment of the polymer. 

Catalyst Development. Traditional slurry polypropylene homopolymer processes suffered from formation of excessive amounts of low grade amorphous polymer and catalyst residues. Introduction of catalysts with up to 30-fold higher activity together with better temperature control have almost eliminated these problems (7). Although low reactor volume and available heat-transfer surfaces ultimately limit further productivity increases, these limitations are less restrictive with the introduction of more finely suspended metallocene catalysts and the emergence of industrial gas-phase fluid-bed polymerization processes. 

In the recipes shown in Table 2, the amount of water can vary widely, depending on the available heat-transfer capacity of the reactor and the rate of polymerization. Each of the monomers has a heat of polymerization of about 75 kj/ mol (18 kcal/mol), so removing the heat of polymerization to control temperature is often the limiting factor on rate of polymerization. 

Assuming that natural gas is used to fire the burner with a known heating value of HVc, calculate the available heat at the operating temperature. A shortcut method usually used for most engineering purposes is ... 

Figure 27-13 shows the available heat in the products of combustion for various common fuels. The available heat is the total heat released during combustion minus the flue-gas heat loss (including the heat of vaporization of any water formed in the POC). 

FIG. 27-13 Available heats for some typical fuels. The fuels are identified by their gross (or higher) heating values. All available heat figures are based upon complete combustion and fuel and air initial temperature of 288 K (60 F). To convert from MJ/Nm to Btii/ft, multiply by 26.84. To convert from MJ/dm to Btii/gal, multiply by. 1588. 

Observable Characteristics -Slfatc (as normally shipped) Solid Color White Odor None. Physical and Chemical Properties - Physical State at IS T7 and I atm. Solid Molecular Weight 142.11 Boiling Point at I atm. Not pertinent (decomposes at 70°C) Freezing Point Not pertinent (decomposes at 70°C) Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.50 at 18.5°C (solid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats afVqtor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion Data not available Heat of Decomposition Not pertinent. 

Vaporization Not pertinent Heat of Combustion Data not available Heat of Decon osition Not pertinent. 

Physical and Chemical Properties - Physical State at 15 T7 and 1 atm. Gas Molecular Weight 116.5 Boiling Point at 1 atm. -18, -28, 245 Freezing Point Not pertinent Critical Temperature (est.) 223.2, 106.2, 379.4 Critical Pressure 592, 40.2, 4.08 Specific Gravity 1.307 at 20 °C (liquid) Vapor (Gas) Density 4.02 Ratio cf Specific Heats of Vapor (Gas) Data not available Latent Heat of Vaporization 83, 46, 1.92 Heat of Combustion Data not available Heat of Decomposition Not pertinent. 

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