Feed inlet temperature

A reactor will be isothermal at the feed inlet temperature Tq if (1) reactions do not generate or absorb significant heat or (2) the reactor is thermostatted by contact with a temperature bath at coolant temperature Tq. For any other situation we will have to solve the energy-balance equation long with the mass balance to find the temperature in the reactor. We therefore must set up these equations for our mixed and unmixed reactors. 

The catalyst (Pd/ZnO) was introduced by wash coating prior to the mounting, which was performed by electron beam welding. Calcination and reduction of the catalyst were performed after the welding procedure. The total heating power of the six heating cartridges was 1.5 kW. Bores were introduced for temperature determination at various positions. The feed inlet temperature was set to 140 °C. 

Figure 2.46 Effect of coolant temperature on CO conversion for the water-gas shift reaction in a micro channel reactor at constant reformate feed inlet temperature of 350 °C. Coolant temperature ( ) 125 ( ) 200 ( ) 225 °C.

Although two reactors are shown in Figure 1, they were not used simultaneously. The reactor shown in the center was the fixed bed reactor which is of primary interest in this contribution. It consisted of a 12.7 mm diameter X 250 mm long steel tube packed with 40/50 mesh catalyst (0.3 mm average particle diameter). The reactor was heated by a nichrome wire coil and was well insulated. The coil spacing was adjusted and was packed in insulation with the intent of making the reactor crudely adiabatic. A variac controlled heater on the reactor inlet and a thermocouple sensor kept the feed to the reactor at the nominal reaction (or feed inlet) temperature of 400°C. The tube of the fixed-bed, reactor was fitted with 12 thermocouples to record the axial temperature profile in the bed (Figure 1). 

This process is technologically more difficult to implement, because it requires the use of muldtube reaction systems with heat transfer fluid flow outside the tubes. However, it is justified by the energy gains and the better performance achieved by operation at a lower reactor feed inlet temperature, and consequently with a lower steam ratio than with adiabatic operation. 

Methanol volumetric flow rate Propylene oxide volumetric flow rate Acid solution volumetric flow rate Feed inlet temperature Reaction temperature Chilled water inlet temperature Chilled water exit temperature Required propylene oxide conversion... 

Figure 14.6 Hot spot formation and methane and oxygen concentration profiles in two ceramic monoliths of different cell density for partial oxidation of methane at 0/C = 0.54 and at a feed inlet temperature of 362 C (a) temperature profile for 400 cpsi, (b) temperature profile for 115 cpsi, (c) concentration profiles for 400 cpsi. (d) concentration profiles for 115 cpsi [65],...

Figure 14.8 Effect of feed inlet temperature and O/C ratio (here shown as O2/C ratio) on reforming efficiency (O/C = 2.5, GffSy=9 900-10 800h" ) [44], (Source Karatzas et al. [44]. Reproduced with permission of Elsevier.)...

Springmarm et ol. [152] simulated a 10-kWei autothermal reformer for gasoline with a one-dimensional, dynamic model. The reformer was a metallic monolith coated with precious metal catalyst. The reformer consisted of two parts both of 70-mm diameter, a small electrically heated monolith only 5-mm long (400 cells per square inch or about 1300-pm channel size) and a second, about 100-mm long monolith (1600 cells per square inch or about 630-pm channel size). Both monoliths were coated with the same catalyst Kinetic data were determined prior to the simulations [56] and heat losses were estimated for the reactors, which is a critical issue. The reformer was operated at a S/C ratio of 2 and an O/C ratio of 0.75. The pressure was 4bar and the feed inlet temperature 500 °C. 

Table 5.15 Comparison of product mass flow rates, reformer efficiency T r, fuel processor efRciency T fp and auxiliary power unit efRciency T apu of steam reforming values are determined for various, feed inlet temperatures Tjn and S/C (SCR) and O/C ratios (expressed as O2/C ratio OCR) as calculated by Specchia etal. [371]. is the fraction of the fuel which is fed to the steam reformer 1- Pr is fed to the burner yp is the dry hydrogen molar fraction of the reformate Wq shows the water balance of the systems, which is positive when the Wq exceeds unity. 

Figure 7.2 Product composition for methanol autothermal reforming as determined in a Microlith reactor prepared by Lyubovsld et al. [190] O/C ratio 0.58 S/C ratio 2 feed inlet temperature 100°C.

Figure 9.43 Efiflciency of the autothermal reformer versus air to fuel ratio as calculated and determined experimentally by Severin et al. The parameters that are varied are feed inlet temperature V and S/C ratio (expressed as %) [618].

The first scale-up requirement for the same feed inlet temperature and composition is that the mean residence time (or mean contact time in heterogeneous systems) is the same in the bench-scale and large-scale unit. This ensures that the Damkdhler number, which is ratio of characteristic flow time to characteristic time for intrinsic reaction, is about the same when the transport effects are either negligible or the same in the two systems. Otherwise, one must account for the change in transport rates with reactor... 

Feed to a reactor is being preheated countercurrently by oil at a temperature of 500°F. The feed is a liquid, entering the exchanger at 200°F and leaving at a controlled temperature of 400°F. Under normal conditions, the feed rate is 100 Ib/min and oil flow is 400 Ib/min the heat capacity of each is 0.8 Btu/ (lb)(°F). Estimate the change in oil flow requited to maintain control as feed flow varies +20 percent from normal. Repeat for variations of +40°F in feed inlet temperature. 

Figure 12.17 Effect of feed inlet temperature on MD flux obtained using PP capillary (Accurel S6/2 MD020CP2N, Table 12.1) with feed flow velocity 0.8 m/s. In DCMD (0.8 m/s permeate flow velocity, 20°C permeate inlet temperature) in SGMD (11.3 m/s humid air velocity, 20°C air inlet temperature) in VMD (3500 Pa downstream pressure). The solid lines are theoretical prediction curves. (Adapted from Khayet et al., 2003c.)...

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