Temperature reactor inlet

Typical adiabatic reactor design involves finding the best values of recycle concentration, inlet temperature, reactor size, recycle flowrate, and per-pass conversion. Of course, not all of these parameters are independent. When the entire process is studied... 

Four important reaction parameters, viz. reactor inlet temperature, reactor inlet pressure, hydrocarbon feed LHSV and H2 HC mole ratio were chosen for the study. A full factorial experimental design is desirable, but four variables at 5 levels requires 625 experimental points even a 1/5 fractional factorial constitutes 125 experiments. Hence a Box-Wilson... 

It is clear that in industrial operations, it is difficult to control many process variables to drive reactions to optimal product distributions. There are four primary control variables for reformers reactor inlet temperatures, reactor pressures, hydrogen content, and feed rate. There are other variables such as feedstock properties and catalyst type. But these variables are generally fixed for a given period of time. 

SO2 gas is catalyticaHy oxidized to SO in a fixed bed reactor (converter) which operates adiabaticaHy in each catalyst pass. The heat of reaction raises the process gas temperature in the first pass to approximately 600°C (see Table 7). The temperature of hot gas exiting the first pass is then lowered to the desired second pass inlet temperature (430—450°C) by removing the heat of reaction in a steam superheater or second boiler. 

The conditions for the carbon bum step are typically less than about 1.0 mol % oxygen, 400°C inlet temperature, 455°C maximum oudet temperature, which is controlled by adjusting the oxygen content of the circulating gas, and 0.45 to 2.2 MPa. The carbon bum is considered to be complete when no exotherm is observed for several hours. The oxygen concentration at all reactor inlets and outlets should be equal at this point. 

Operating conditions The reactor is 10 cm ID, input of ethylbenzene is 0.069 kg mol/h, input of steam is 0.69 kgmol/h, total of 2,500 kg/h. Pressure is 1.2 bar, inlet temperature is 600 C. Heat is supplied at some constant temperature in a jacket. Performance is to be found with several values of heat transfer coeff cient at the wall, including the adiabatic case. 

The second and third reactors contain more catalyst than the first one to enhance the slow reactions and allow more time in favor of a higher yield of aromatics and branched paraffins. Because the dehydrogenation of naphthenes and the dehydrocyclization of paraffins are highly endothermic, the reactor outlet temperature is lower than the inlet temperature. The effluent from the first and second reactors are reheated to compensate for the heat loss. 

Figure 5 depicts the effect of calcination temperature on subsequent catalyst activity after reduction at 300°C (572°F). Activity was measured in laboratory tubular reactors operating at 1 atm with an inlet gas composition of 0.40% CO, 25% N2, and 74.6% H2, and an inlet temperature of 300°C. Conversion of CO is measured and catalyst activity is expressed as the activity coefficient k in the first order equation ... 

The selection of optimum reactor inlet and outlet temperatures is affected by catalyst activity, and catalyst stability, and the need to minimize operating and investment costs. When the special BASF methanation catalyst is used, inlet temperatures of 260°-300°C or even lower are quite acceptable (see Table II). The final decision on design inlet temperature is affected by engineering requirements. 

Dr. Moeller I think to answer this question now is a bit difficult. It s just a mechanical problem of the maximum temperature the recycle compressor can handle. So, in the end, we will go to the inlet temperature to the compressor in the range of the inlet temperature to the reactor. So what we are endeavoring to attain is a simple reaction system consisting of an adiabatic reactor in series with waste heat boilers and nothing more than one recycle compressor. These compressors are used in the chemical industry with no problem in operation. So, in the end, you can go to hot recycle with an inlet compressor temperature the same as the inlet reactor temperature. All the heat from... 

HEATRO = heat of reaction for the polymerization, cal/mole TF = reactor inlet temperature, °C DM0 = reactor fluid density, mole/l BETA = 3-scission reaction rate constant... 

Example 5.6 Hydrocarbon cracking reactions are endothermic, and many different techniques are used to supply heat to the system. The maximum inlet temperature is limited by problems of materials of construction or by undesirable side reactions such as coking. Consider an adiabatic reactor with inlet temperature Tm. Then T z) < T, and the temperature will gradually decline as the reaction proceeds. This decrease, with the consequent reduction in reaction rate, can be minimized by using a high proportion of inerts in the feed stream. 

Example 5.10 A liquid-phase, pilot-plant reactor uses a 12-ft tube with a 1.049-in i.d. The working fluid has a density of 860 kg/m, the residence time in the reactor is 10.2 s, and the Reynolds number is 8500. The pressure drop in the pilot plant has not been accurately measured, but is known to be less than 1 psi. The entering feed is preheated and premixed. The inlet temperature is 60°C and the outlet temperature is 64°C. Tempered water at 55°C is used for cooling. Management loves the product and wants you to design a plant that is a factor of 128 scaleup over the pilot plant. Propose scaleup alternatives and explore their thermal consequences. 

Example 8.9 Find the temperature distribution in a laminar flow, tubular heat exchanger having a uniform inlet temperature and constant wall temperature Twall- Ignore the temperature dependence of viscosity so that the velocity profile is parabolic everywhere in the reactor. Use art/P = 0.4 and report your results in terms of the dimensionless temperature... 

Consider the scaleup of a small, tubular reactor in which diffusion of both mass and heat is important. As a practical matter, the same fluid, the same inlet temperature, and the same mean residence time will be used in the small and large reactors. Substitute fluids and cold-flow models are sometimes used to study the fluid mechanics of a reactor, but not the kinetics of the reaction. 

Solution There are several theoretical ways of stabilizing the reactor, but temperature control is the normal choice. The reactor in Example 5.7 was adiabatic. Some form of heat exchange must be added. Possibilities are to control the inlet temperature, to control the pressure in the vapor space thereby allowing reflux of styrene monomer at the desired temperature, or to control the jacket or external heat exchanger temperature. The following example regulates the jacket temperature. Refer to Example 5.7. The component balance on styrene is unchanged from Equation (5.29) ... 

Use the inlet temperature rather than the jacket temperature to control the reactor in Example 14.8. 

As the whole reaction occurs at the begirming of the reactor, the process fluid inlet temperature has been modified with the adiabatic increase of temperature ... 

Figure 2.55 The effect of cooling gas flow rate and inlet temperature on CO conversion in the WGS reactor, as described in [165]. The cooling gas flow rate was varied for a fixed reaction gas flow rate and three different inlet temperatures were considered.

One of the main conclusions of Kenat et al., was that the largest changes in polymer, mean-chain length, occur from the effect of inlet temperature changes and that, therefore, controlling inlet temperature, rather than reactor temperature, is beneficial to reactor performance. 

With dt = 0.025 m study the effect of varying inlet temperature (Tq = 600, 640, 660 K, with constant jacket temperature. Note the hot spot effect in the reactor temperature profile. 

There are circumstances when a complex process may involve two competing (i.e., opposing) dynamic effects that have different time constants. One example is the increase in inlet temperature to a tubular catalytic reactor with exothermic kinetics. The initial effect is that the exit temperature will momentarily decrease as increased conversion near the entrance region depletes reactants at the distal, exit end. Given time, however, higher reaction rates lead to a higher exit temperature. 

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