Partial oxidation mode

Systems Analysis Figure 1 shows a concept identified by NETL for a integrated fuel processor/ fuel cell system targeted for diesel APUs. There are several favorable attributes of this system. For example, startup occurs by firing an internal combustor in the dual reactor reformer. This provides heat to the ATR reformer (via conduction) as well as supplying heat to the fuel cell cathode via direct exhaust from the combustor or preheated air from the heat exchanger (optional). If necessary, the ATR is fired in a partial oxidation mode to aid in heatup and to provide heat to the anode side of the... 

As a last measure, electrical pre-heating of a small and separate monolith at the inlet of the water-gas shift reactor was assumed, similar to the design of the reformer reactor (Figure 5.59) [389]. The reformer was then operated in the partial oxidation mode rather than under conditions of total oxidation. Through these means. 

Partial oxidation of methane to syngas over Ni and Co catalysts was effected by use of microwave irradiation, and compared with conventional heating [73]. Although the same conversion levels and H2/CO ratio (2.0 0.2) were observed, the temperature of the catalyst bed was much lower (200 K) when microwave irradiation was used than with conventional heating. Under both activation modes the Ni-based... 

An excellent review on protein hydrolysis for amino acid composition analysis has been published by Eountoulakis and Lahm [190], Hydrolysis can be performed by either chemical (under either acidic or basic conditions) or enzymatic means. The acidic hydrolysis itself can be carried out in a liquid or a gas-phase mode. The conventional acid hydrolysis uses 6M HCl for 20-24 h at 110°C under vacuum [200], In these conditions, asparagine and glutamine are completely hydrolyzed to aspartic acid and glutamic acid, respectively. Tryptophan is completely destroyed (particularly in the presence of high concentrations of carbohydrate), while cysteine and sometimes methionine are partially oxidized. Tyrosine, serine, and threonine are partially destroyed or hydrolyzed and correction factors have to be applied for precise quantification [190,201],... 

The reactor impregnated with nickel showed inferior performance again. Deactivation was observed, which was assumed to originate from coking, sintering, oxidation of the nickel or even losses of volatile nickel species. With increasing temperature, enhanced formation of by-products, namely methane and ethane, was observed in the reformate both under partial oxidation conditions and in the autothermal mode, which was attributed to thermal cracking. 

In Fig. 5.13a at high power (point A) a low O2 partial pressure ofp(C>2) = 10 mPa is achieved. The decrease in discharge power (transition from A to B) shows a continuous increase in reactive gas partial pressure. Beyond point B, a further continuous increase in reactive gas partial pressure can be achieved only by increasing the discharge power. An abrupt transition from the metallic to the oxide mode (point D) would be observed for a further decrease of discharge power. 

In the batch mode, M wiU be oxidized by OH radicals to M (Fig. 8-2, situation A). Because initially M is in a very large excess, the OH radicals will preferentially be scavenged by M. Therefore, the concentration of M rises and subsequently it competes efficiently with M for OH radicals leading slowly to the formation of M . If most of M is oxidized the concentration of M reaches its maximum and it wiU preferably react with OH radicals leading to a decrease in its concentration. Finally, the concentration of M increases. Therefore, the batch photoreactor configuration seems to be best suited for the partial oxidation of hazardous pollutants in water. The accumulation of oxidation products M must be taken into account with respect to their toxicity and their environmental impact... 

The opposing reactant contactor mode applies to both equilibrium and irreversible reactions, if the reaction is sufficiently fast compared to transport resistance (diffusion rate of reactants in the membrane). This concept has been demonstrated experimentally for reactions requiring strict stoichiometric feeds, such as the Claus reaction, or for kinetically fast, strongly exothermic heterogeneous reactions, such as partial oxidations. Triphasic (gas/liquid/solid) reactions, which are limited by the diffusion of the volatile reactant (e.g., olefin hydrogenation), can also be improved by using this concept. 

There has been eonsiderable recent interest in partial oxidation of alkanes for new routes to chemical synthesis from light alkanes, and this research has been summarized extensively[l-3]. While much of this research uses dilution and low flow rates to attain temperatures between 200 and 600°C, another mode of operation involves very short contact times with no dilution to increase the temperature to -1000°C and decrease the catalyst contact time to 1 milUsecond. Recent research with millisecond adiabatic reactors have been carried out by Green et al[4], Lunsford et al[5], Choudhary et al[6], and many other research groups. 

The new process is realized by direct contacting of hydrogen and oxygen (without inert gas) using a micromixer, in the presence of a heterogeneous catalyst in a trickle-bed mode [12]. The key to high selectivity is to have a noble metal catalyst in a partially oxidized state. Otherwise, either only water is formed or no reaction is achieved. 

Fuel reformer operation is generally divided into two operating modes start-up and normal partial oxidation. During start-up, the fuel processor bums fuel at near stoichiometric conditions until critical system temperatures and pressures stabilize to target values. Once the target conditions are reached, the reformer operates in normal mode in which the fuel processor bums fuel at very rich conditions. Since these modes are comprised of considerably different operating conditions, it follows that the emissions associated with each of these modes are also considerably different. 

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