Heated tube reactor

Lithium greases can be manufactured by continuous process in a heated tube reactor. This process is convenient and problem-free for simple lithium soap thickened greases. However, lithium complex greases having much higher thickener concentrations resulted in increased difficulties during the continuous production. These difficulties include wide fluctuations in flow rates, cessation of flow and resultant downtime, and greatly reduced imit production capacity. 

The highly exothermic nature of the butane-to-maleic anhydride reaction and the principal by-product reactions require substantial heat removal from the reactor. Thus the reaction is carried out in what is effectively a large multitubular heat exchanger which circulates a mixture of 53% potassium nitrate [7757-79-1/, KNO 40% sodium nitrite [7632-00-0], NaN02 and 7% sodium nitrate [7631-99-4], NaNO. Reaction tube diameters are kept at a minimum 25—30 mm in outside diameter to faciUtate heat removal. Reactor tube lengths are between 3 and 6 meters. The exothermic heat of reaction is removed from the salt mixture by the production of steam in an external salt cooler. Reactor temperatures are in the range of 390 to 430°C. Despite the rapid circulation of salt on the shell side of the reactor, catalyst temperatures can be 40 to 60°C higher than the salt temperature. The butane to maleic anhydride reaction typically reaches its maximum efficiency (maximum yield) at about 85% butane conversion. Reported molar yields are typically 50 to 60%. 

The first large-scale commercial oxychlorination process for vinyl chloride was put on-stream in 1958 by The Dow Chemical Company. This plant, employing a fixed-tube reactor containing a catalyst of cupric chloride on an active carrier, produced 1,2-dichloroethane from ethylene. The high temperatures involved in the reaction were moderated by a suitable diluent. The average heat output from the reaction is 116 kJ/mol (50,000 Btu/lb mol). 

Exothermic processes, with cooling through heat transfer surfaces or cold shots. In use are sheU-and-tube reactors with smaU-diameter tubes, or towers with internal recirculation of gases, or multiple stages with intercoohng. Chlorination of methane and other hydrocarbons results in a mixture of products whose relative amounts... 

Heat exchanger-like, multi-tube reactors are used for both exothermic and endothermic reactions. Some have as much as 10,000 tubes in a shell installed between tube sheets on both ends. The tubes are filled with catalyst. The larger reactors are sensitive to transient thermal stresses that can develop during startup, thermal runaways and emergency shut downs. 

It is prepd by heating a mixt of N trifluoride, As pentafluoride, and F in a Monel tube reactor at 200° for 2-5 days (Ref 1) or by passage of the same reagents thru a glow discharge (Ref 4). Differential thermal analysis indicates that on slow heating the decompn starts ca 270° (Ref 2). Its IR and NMR spectra are given in Ref 3. 

Design a shell-and-tube reactor that has a volume of 24 m and evaluate its performance as the reactor element in the process of Example 6.2. Use tubes with an i.d. of 0.0254m and a length of 5m. Assume components A, B, and C all have a specific heat of 1.9 kJ/(kg-K) and a thermal conductivity of 0.15W/(m-K). Assume 7 ,>, = 70°C. Run the reaction on the tube side and assume that the shell-side temperature is constant (e.g., use condensing steam). Do the consecutive, endothermic case. 

All conventional reactors, tested before using the micro reactor (simply since micro reactors were hardly available at that time), only fulfilled the demands of one measure, at the expense of the other measures. For instance, a single-tube reactor can be operated nearly isothermally, but the performance of the oxidative dehydrogenation suffers from a too long residence time. A short shell-and-tube reactor provides much shorter residence times at improved heat transfer, which however is still not as good as in the micro reactor. 

The pressure-drop and heat-transfer coefficients in empty tube reactors can be calculated using the methods for flow in pipes given in Volume 1. 

The single-jacketed tube reactor is the simplest type of tubular reactor to conceptualize and to fabricate. It may be used only when the heat transfer requirements are minimal because of the low surface area to volume ratio characteristic of these reactors. 

To exploit the numerous applications for floating catalyst VGCF in engineered plastics, production rates are projected to be on the order of several pounds per hour from a single tube reactor. Demonstration experiments on a small scale have shown feasibility of accomplishing the desired rate of production. Economic production of such quantities will involve recapture of energy in the heated unreacted gas which exits the reactor, as well as automated collection, debulking, and preform fabrication systems. 

Stainless steel is the material of choice for process chemistry. Consequently, stainless steel microreactors have been developed that include complete reactor process plants and modular systems. Reactor configurations have been tailored from a set of micromixers, heat exchangers, and tube reactors. The dimensions of these reactor systems are generally larger than those of glass and silicon reactors. These meso-scale reactors are primarily of interest for pilot-plant and fine-chemical applications, but are rather large for synthetic laboratories interested in reaction screening. The commercially available CYTOS Lab system (CPC 2007), offers reactor sizes with an internal volume of 1.1 ml and 0.1 ml, and modular microreactor systems (internal reactor volumes 0.5 ml to... 

Plug flow reactor (PFR) a tube reactor in which the reactants are fed continuously at one end and the products are removed continuously from the other end concentration and heat generation change along the length of the tube the PFR is often used for potentially hazardous reactions because of the relatively small inventory in the system. 

The pyrolytic reforming reactor was a packed bed in a quartz tube reactor. Quartz was selected to reduce the effect of the reactor construction material on the hydrocarbon decomposition rate. ° The reactor was packed with 5.0 0.1 g of AC (Darco KB-B) or CB (BP2000) carbon-based catalyst. The reactor was heated electrically and operated at 850—950 °C, and the reactants had a residence time of 20—50 s, depending on the fuel. The reactor was tested with propane, natural gas, and gasoline as the fuels. Experiments showed that a flow of 80% hydrogen, with the remainder being methane, was produced for over 180 min of continuous operation.The carbon produced was fine particles that could be blown out... 

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