Tubular reactor coiled

Figure 11. Hypothetical conversion as a function of Reynolds number in helically coiled tubular reactors...

The maximum rate of polymerization has been confirmed to occur at the laminar-turbulent flow transition. The rate of polymerization was observed to be maximum at the transition for both straight reactors as well as for the helically-coiled reactor for which the transition is at a Reynolds number higher than that of the straight tube. The helically coiled tubular reactor is of industrial interest since it is much more compact and, consequently, the cost and the temperature control problems are more tractable. 

Tubular reactors normally take one of three geometries. The most common consists of tubing of the same diameter connected by U bends. The internal diameters are often 4 in. The total length of one reactor coil may be 300 ft. Four to eight coils are commonly placed within a single furnace. 

Design data are 1kg water per hour, P<300 bar and T<600 °C kept constant by a fluidized sandbath in which a 6 m tubular reactor coil with an inner diameter of 2 mm is submerged. 33 thermocouples measure the reaction temperature profiles. Water, organic material and the pressurized air can be preheated. 

The benchscale plant principally follows the design scheme of the labscale plant, but is equipped with a tubular reactor coil made of Inconel 625, 15 metres in length, the 8 mm inner diameter of which is good for a throughput of 10 kg/h of water. Tests with model substances like ethanol and toluene showed results comparable to those of the labscale plant. 

Tijssen, R. Axial dispersion and flow phenomena in helically coiled tubular reactors for flow analysis and chromatography. Anal. Chim. Acta 1980, 114, 71. 

D.F. Leclerc, P.A. Bloxham, E.C. Toren Jr., Axial dispersion in coiled tubular reactors, Anal. Chim. Acta 184 (1986) 173. 

R. Tijssen, Axial Dispersion and Flow Phenomena in Helically Coiled Tubular Reactors for Flow Analysis and Chromatography. Anal. Chim. Acta, 114 (1980) 71. 

The hydrocarbon gas feedstock and Hquid sulfur are separately preheated in an externally fired tubular heater. When the gas reaches 480—650°C, it joins the vaporized sulfur. A special venturi nozzle can be used for mixing the two streams (81). The mixed stream flows through a radiantly-heated pipe cod, where some reaction takes place, before entering an adiabatic catalytic reactor. In the adiabatic reactor, the reaction goes to over 90% completion at a temperature of 580—635°C and a pressure of approximately 250—500 kPa (2.5—5.0 atm). Heater tubes are constmcted from high alloy stainless steel and reportedly must be replaced every 2—3 years (79,82—84). Furnaces are generally fired with natural gas or refinery gas, and heat transfer to the tube coil occurs primarily by radiation with no direct contact of the flames on the tubes. Design of the furnace is critical to achieve uniform heat around the tubes to avoid rapid corrosion at "hot spots."... 

The resistance of titanium in nitric acid is good at most concentrations and at temperatures up to boiling . Thus tubular heat exchangers are used in ammonium nitrate production for preheating the acid prior to its introduction into the reactor via titanium sparge pipes. In explosives manufacture, concentrated nitric acid is cooled in titanium coils and titanium tanks are... 

The precondensation can be earned out continuously with the use of a tubular reactor at a temperature of 290-310°C.56 The tubular reactor is a 4-m-long coiled pipe with a diameter of 4 mm which is heated at 300°C. At the end of the pipe is a valve which is regulated so that the pressure is 1.5 bar. The residence time in the pipe is only seconds. The prepolymer obtained can be postcondensed in the solid state to a high molecular weight. 

The work reported here used a tubular reactor of approx. 2.5 cm id and 150 meters in length. The reactor, lined with a fluorinated polymer, was coiled in a helical shape. The recipe employed standard concentrations of initiator and emulsifier. 

Example 3.5 A 1-in i.d coiled tube, 57 m long, is being used as a tubular reactor. The operating temperature is 973 K. The inlet pressure is 1.068 atm the outlet pressure is 1 atm. The outlet velocity has been measured to be 9.96 m/s. The fluid is mainly steam, but it contains small amounts of an organic compound that decomposes according to first-order kinetics with a half-life of 2.1s at 973 K. Determine the mean residence time and the fractional conversion of the organic. 

Other configurations that are used include an concentric electrode setup in a tubular reactor, where the discharge still is capacitivily coupled. Also, inductive coupling has been used, with a coil surrounding the tubular reactor [146, 147]. 

For fast reactions (i.e., < 1 min.), open tubular reactors are commonly used. They simply consist of a mixing device and a coiled stainless steel or Teflon capillary tube of narrow bore enclosed in a thermostat. The length of the capillary tube and the flow rate through it control the reaction time. Reagents such as fluorescamine and o-phthalaldehyde are frequently used in this type of system to determine primary amines, amino acids, indoles, hydrazines, etc., in biological and environmental samples. 

Fig. 2.4p shows three types of post-column reactor. In the open tubular reactor, after the solutes have been separated on the column, reagent is pumped into the column effluent via a suitable mixing tee. The reactor, which may be a coil of stainless steel or ptfe tube, provides the desired holdup time for the reaction. Finally, the combined streams are passed through the detector. This type of reactor is commonly used in cases where the derivatisation reaction is fairly fast. For slower reactions, segmented stream tubular reactors can be used. With this type, gas bubbles are introduced into the stream at fixed time intervals. The object of this is to reduce axial diffusion of solute zones, and thus to reduce extra-column dispersion. For intermediate reactions, packed bed reactors have been used, in which the reactor may be a column packed with small glass beads. 

A continuous MW reactor (CMR), which operates by passing a reaction mixture through a pressurized tubular microwave-transparent coil and a MW batch reactor (MBR), have been developed by CSIRO in Australia and are used for organic synthesis on the laboratory scale [8]. The CMR can be operated at pressures up to 1400 kPa and temperatures up to 200 °C and the MBR at pressures and temperatures up to 10 MPa and 260 °C. 

The reactor (Fig. 10.3) consists of microwave cavity fitted with a tubular coil (3x3 mm) of microwave-transparent, inert material. The coin is attached to a meter-... 

Tubular reactors are most often used, although autoclave reactors are also employed. Tubular reactors consist of a number of sections, each with an inner diameter of 2-6 cm and length of 0.5-1.5 km, arranged in the shape of an elongated coil. The polymerization mixture has very high linear velocities (>10m s-1) with short reaction times (0.25-2 min). Trace amounts of oxygen (<300 ppm) are typically used as the initiator, often in combination... 

B. Postcolumn Derivatization Three types of reactors for postcolumn derivatization are used, depending on reaction kinetics. Straight, coiled, and knitted open-tubular reactors are used for fast reactions, whereas packed-bed reactors are used for intermediate kinetics. Segmented-stream reactors are used for slow reactions. The simplest reactors are the open-tubular reactors a T connector is the most common. Pickering44 has described the performance requirements for instrumental components of HPLC postcolumn systems. 

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