We can furnish either a fixed internal thermocouple in each zone or a single movable thermocouple that can be used to measure the temperature at points along the catalyst bed. External thermocouples are typically provided for control of each zone of the heater.
Gas Feed Systems
Various gas feeds can be set up and operated from a Gas Distribution Panel. In order to deliver a constant flow of gas to a reactor, it is necessary to provide gas at a constant pressure to an electronic Mass Flow Controller. This instrument will compare the actual flow rate delivered to the set point chosen by the user, and automatically adjust an integral control valve to assure a constant flow. Care must be taken to size these controllers for the specific gas, the flow rate, and the pressure of operation. A mass flow controller needs a power supply and read-out device, as well as a means of introducing the desired set point.
When ordering mass flow controllers, you will need to specify:
1. Type of gas to be metered (e.g. N2, H2, CH4)
2. Maximum operating pressure of the gas (100 or 300 bar)
3. Maximum flow rate range in standard cc’s per minute (sccm)
4. Pressure for calibration of the instrument
Mass flow controllers are available for use to 1500 psi and to 4500 psi. Considerable savings can be obtained if the mass flow controller is to be used only to 1500 psi.
The schematic below depicts the installation of a mass flow controller for the introduction of gas to a continuous-flow reaction system. Such installations can be enhanced with the addition of a by-pass valve for rapid filling.
A purge line can also be added. It is typically used for feeding nitrogen or helium to remove air before reaction or to remove reactive gases before opening the reactor at the end of a run. The purge line includes a shut-off valve, metering valve, and a reverse-flow check valve.
Shut-off valves can be automated when using a 4871 Control system.
Liquid Metering Pumps
High pressure piston pumps are most often used to inject liquids into a pressurized reactor operating in a continuous-flow mode. For low flow rates, HPLC pumps, many of which are rated for 5000 psig, are excellent choices. Typical flow rates for pumps of this type range up to 10 or 40 mL per minute. Pumps are available to accommodate manual control from their digital faceplate or computer-controlled from a 4871 Process Controller.
Chemical feed pumps are our recommendation for continuous feeding of liquids when the desired flow rate is greater than 2 liter per hour. Here we will try to help you find a suitable pump. We will need to know the type of liquid; the minimum, typical, and maximum desired feed rate; the maximum operating pressure; and any special operating considerations such as explosion proof operation or corrosion possibilities.
Back Pressure Regulators
In addition to supplying gases to a reaction through electronic mass flow controllers, the reactor is kept at a constant pressure by installing a Back Pressure Regulator (BPR) downstream of the reactor. This style of regulator will release products only when the reactor pressure exceeds a preset value.
When a BPR is used in conjunction with mass flow controllers, the user is assured that a constant flow of gas is passing through a reactor, which is being held at a constant pressure. This provides for the highest degree of control and reproducibility in a continuous-flow reactor system.
Cooling Condensers
It is often desired to cool the products of the reaction prior to handling them. For this purpose, tube-and-shell heat exchangers are available to act as the cooling condensers. An adaptation of our standard condensers provides an excellent design. Descriptions and available sizes are found in the 4500 Catalog, Stirred Reactors and Pressure Vessels.
Gas/Liquid Separators
Tubular reactors operating in continuous-flow mode with both gas and liquid products will also require a Gas/Liquid Separator for smooth operation. The separator is placed downstream of the reactor, often separated from the reactor by a cooling condenser. In the separator vessel, liquids are condensed and collected in the bottom of the vessel. Gases and non-condensed vapors are allowed to leave the top of the vessel and pass on to the back pressure regulator. It is important to operate the BPR with a single fluid phase to prevent oscillation of the reactor pressure.
The gas/liquid separator can be sized large enough to act as a liquid product receiver that can be manually drained periodically. Many of the non-stirred pressure vessels listed in our 4500 catalog are ideally suited for use as gas/liquid separators. Vessels of 300, 600, 1000, or 2000 mL are commonly chosen.
Control and Data Acquisition Systems
A variety of solutions exist to meet the needs of system operators. System accessories such as heaters, mass flow controllers, and pumps can be obtained with individual control packages to create a manual, distributed control system. Each of the various controllers that are equipped with an output signal can be incorporated into a PC-based data acquisition system.
Series 5400 Ordering Guide
A composite identification number to be used when ordering a 5400 Series Tubular Reactor System can be developed by combining individual symbols from the separate sections.
Example: A ½-inch by 24-inch length tubular reactor, cart mounting, T-316 Stainless Steel, 115V, three zone split tube heater, 3000 psi gage, programmable temperature control, two gas feeds, one purge line, one liquid metering pump, gas/liquid separator (1000 mL)
5402C-SS-115-ST3(24)-3000-DCS-GF2-LF1-ITW-GLS1000
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A. Model Number
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Size
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5401
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3/8 in
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5402
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1/2 in
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5403
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1 in
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5404
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1.5 in
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Add suffix F for Floor Stand mounting
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Add suffix B for Bench-top mounting
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Add suffix C for Cart mounting
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B. Material of Construction
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-SS
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T316 Stainless Steel
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-HC
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Alloy 276
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-TI
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Titanium
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-IN
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Alloy 600
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-MO
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Alloy 400
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C. Electrical Supply
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-115
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115 Volt, 50/60Hz
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-230
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230 Volt, 50/60Hz
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D. Heater Options
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-ST1(#)
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Split Tube, 1-zone
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-ST3(#)
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Split Tube, 3-zone
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-FM(#)
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Flexible Mantle
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-WJ(#)
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Welded Jacket
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Add suffix (6), (12), (24), (30), (36) for heated length (in.)
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E. Maximum System Pressure
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-1500
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1500 psi / 100 bar
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-3000
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3000 psi / 200 bar
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-4500
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4500 psi / 300 bar
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F. Control
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-PCC
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PC-based Process Control (4871-style)
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-DCS
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Table-top Chasses (4838-style)
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G. Custom Options
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-GF(#)
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Number of gas feeds
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-PL
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Purge gas feed line
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-LF(#)
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Number of liquid feeds
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-ISP
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Internal pre-heat spiral (5403/5404 only)
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-CSS
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Catalyst support spools (5403/5404 only)
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-ITW
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Internal thermowell, with T/C
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-CHX
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Cooling heat exchanger
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-GLS(#)
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Gas/Liquid Separator, Volume (300, 600, 1000, 2000 mL)
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-SPH
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Separator heater
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-TR(#)
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Number of gas tank regulators
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-AP*
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Automated pressure control*
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-ASV*
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Automated shut-off valves*
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*Available only with 4871 Process Control (PCC)
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H. Certifications
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-No symbol
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No certification required
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-PARR
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Parr Certification
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-ASME
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ASME certification
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-CE
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European CE/PED Certification
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