Nitrogen residence time

The majority of thermal polymerizations are carried out as a batch process, which requires a heat-up and a cool down stage. Typical conditions are 250—300°C for 0.5—4 h in an oxygen-free atmosphere (typically nitrogen) at approximately 1.4 MPa (200 psi). A continuous thermal polymerization has been reported which utilizes a tubular flow reactor having three temperature zones and recycle capabiHty (62). The advantages of this process are reduced residence time, increased production, and improved molecular weight control. Molecular weight may be controlled with temperature, residence time, feed composition, and polymerizate recycle. 

Because of the formation of nitrogen oxides, a steady-state ozone concentration cannot be obtained instead, due to the buHdup of nitrogen oxides, an increase in residence time in the discharge results in a decrease in ozone concentration beyond the maximum value. Thus, there is an optimum residence time for maximum ozone production. 

The important parameters in the reduetion of NO as seen in the above equation are the temperature of the flame, the nitrogen and oxygen eontent and the resident time of the gases in the eombustor. Figure 10-21 is a eorrelation between the adiabatie flame temperature and the emission of NOx- Reduetion of any and all these parameters will reduee the amount of NOx emitted from the turbine. 

NOj, levels in the FCC flue gas typically range from 50-500 ppm. Nitrogen content of the feed, excess oxygen, regenerator residence time, dense phase temperature, and CO promoter all influence the concentration of NO. ... 

The thermal cracking of a light ffaction of mixed plastics waste was carried out in a fluidised bed reactor and the fractions obtained were analysed by elemental analysis, gas chromatography and ashing. The main components of the waste were PE and PP with a small amount of PS and the bed was fluidised by pyrolysis gas, nitrogen or preheated steam. Experiments conducted at different temperatures and residence times were compared by calculating the crack severity for each experiment. The results obtained revealed that the amounts of ethene and propene obtained by pyrolysis with steam were comparable with those obtained using a commercial steam cracker. 

GP 2] [R 2] A residence time variation was performed imder constant gas composition, temperature and pressure, but with varying flow rate. On increasing the residence time from 0.5 to 8 s, reaction rates on OAOR-modified silver decreased notably from 9.5 10 mol s to about 1 10 mol s mT (5 vol.-% ethylene, 50 vol.-% oxygen, balance nitrogen 20 bar 0.5-8 s) [4]. The selectivity decreases from 43 to 21%. 

GP 11] ]R 19] Using the above visual inspection technique, the minimum residence time can be estimated. Flow was increased and so the residence time decreased, until the whole reactor was glowing. This corresponds to a residence time as low as approximately 50 ps (0.1 slpm hydrogen, 0.14 slpm oxygen, 0.45 slpm nitrogen) [9]. 

Buesseler et al. (1992b) proposed a method to circumvent these difficulties in comparing residence times. They argued that the deficiency in total " Th with respect to indicates a flux of " Th in association with particles sinking out of the euphotic zone. If the POC (or particulate organic nitrogen, PON)/ Th ratio of these sinking particles is known, a POC (or PON) flux can be calculated as ... 

Four variables were studied in the part of the experimental program which examined the first step of the proposed two-step process. The variables were reaction temperature (413-454 C), solvent to coal ratio (2 1 and 3 1), residence time (0-5 minutes), and pressure (300-1800 psi nitrogen). Four experiments were done to simulate the second step, in which hydrogenated solvent and molecular hydrogen would be used to lower the sulfur content of the product. These experiments were done at 441 C for 2 minutes, with and without molecular hydrogen and recycle solvent containing 25 weight percent Tetralin. 

Figure 4, Mean nitrogen solubility index (%) for protein flour dry roasted under various processing conditions bean/bean ration (1/10, 1/15) residence time (1, 2 min) and bead...

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