Thermocouple sliding

The liquid is initially distributed by means of four small 1/16" pipes. An inert bed, realized with inert alumina pellets, ensured preheating, liquid saturation and an uniform distribution of both fluids. The reactor is provided with an axial thermocouple well. A sliding thermocouple can be moved along the bed axis allowing to measure the axial temperature profile and to check the isothermal operation of the reactor. 

The reactor was a tube of 446 stainless steel with an internal diameter of % in. and of 20 in. total length. The catalyst bed was the central 2 in., and a furnace surrounding the tube controlled the temperature to 1°. A sliding thermocouple in a central well of 3 -in. o.d. measured the bed temperature. The catalyst bed volume was 10 cc., and the rest of the reactor was filled with stainless steel spacers to reduce the dead space. Steam was heated to 650° in a preheater and mixed with the reacting gas or air at the top of the reactor, which was operated at atmospheric pressure. The supply of gas and steam was measured by flow meters and controlled by solenoid valves activated by a timer so that the catalyst could be fed on hourly or half-hourly cycles with steam and hydrocarbon or steam and air. In this way, any carbon laydown could be measured by analyzing for carbon dioxide in the air from the second (regeneration) cycle. 

Since commercially available monolithic supports for environmental catalysts are not suitable for this class of applications, as explained above, in the early studies homemade high conductivity structured catalysts were prepared by assembling washcoated slabs of aluminium or stainless steel to form plate-type catalytic cartridges, which were also equipped with thermowells for sliding thermocouples in order to monitor the temperature distributions. The washcoat consisted of Pd (3%w/w) on y-Al203, and the catalysts were tested in the oxidation of CO, selected as a model exothermic reaction. 

Fig. 1. Scheme of apparatus. 1—Discharge tube 2—flask with water 3—nozzle 4—reaction vessel 5—electrical furnace 6—stopcock valve 7—thermocouple 8—trap 9—manometer 10—slides 11—spectrograph slit 12—hydroxyl source 13—discharge tube electrodes 14—transformer 15—vessel of prefixed volume. 

The pressure of the system was controlled to within 0.5 mm Hg for each series by a Cartesian diver manostat connected to a positive air leak, a vacuum pump, and a surge volume of 12 liters. An absolute mercury-in-glass manometer with a 0.1 mm sliding vernier was used to measure the pressure. Temperatures were monitored via two copper-constantan thermocouples one was located just above the liquid surface and the other just below it. Maximum differences of 0.4°C were detected, but an average of the two readings was reported to 0.2°C. Glacial acetic acid and acetone, both meeting ACS specifications, were used. 

Several micro methods have been developed for the determination of the melting point, using one or two crystals of the substance. In most of these methods the crystals are placed on a slide and covered with a cover glass. The slide is then placed on a metal plate which is heated electrically by resistance wires. The temperature is measured by a thermometer or thermocouple placed close to the sample. The change in the crystals is observed through a magnifying lense or a microscope. 

The Leeds Northruj) transformation-point indicator is a semiautomatic recorder giving a continuous curve of temperature temperature difference. The complete apparatus includes the recorder, two wall-type double-suspension galvanometers, furnace, rheostat and thermocouples. The recorder is the potentiometer type with a drum chart. The potentiometer slide wire is mounted on the same shaft as the... 

REACTION CELL. The reaction cell was made of a silicone rubber gasket sandwiched between two pyrex cover slides. The cell was pressed against the flat face of a cylindrical heater, which was proportionally controlled to within 1°C. Two small holes were bored near the top of the rubber gasket for inserting a thermocouple and for filling the cell. 

Normal procedure was to evacuate the entire reactor system prior to startup. The feed-pump was then started and the oven temperature slowly raised until liquids began to accumulate in the trap. The catalyst bed temperature was monitored by a thermocouple sliding in an axial sheath. 

M. Furey [16] carried out a direct experimental comparison of the temperatures measured by the dynamic thermocouple technique with the temperatures indicated by an embedded thermocouple located 0.025 cm from the rubbing interface of a constantan ball sliding on a rotating steel ring. The temperatures sensed by the dynamic thermocouple were higher than those of the embedded thermocouple as the dynamically measured temperature increased, the proportionate lag in the temperature by the embedded thermocouple became greater. 

Examples of good preventive maintenance activities include (1) establish the frequency of lubrication and what types of oil or grease must be used (2) check for oil leaks and have a procedure to correct/eliminate them (3) check heaters, thermocouples, pressure transducers, and so on (4) set up schedules and procedure to clean machines and molds/dies (barrels, screws, sliding mechanisms, clamps, etc.) (5) check control circuits (electrical, hydraulic, mechanical, etc.) (6) schedule checks of conditions wherever questions of alignment, level, parallelism (mold parts, mold press, die system, etc.), and other similar situations exist (7) set up a schedule to check safety devices on all equipment and (8) schedule sessions to repeat instructions on safety equipment procedures to all personnel. Figure 11-8 shows where accidents usually occur (324, 325). 

Fig. 6.4 General overview of the EGA probe attached to the lithium ion attachment mass spectrometer used extended view of EGA probe showing (1) sampler, (2) sampler holder, (3) heater, (4) thermocouple, (5) gas inlet, and the whole system of EGA probe and lAMS, showing (6) sampler, (7) isolation valve, (8) detachable flange, (9) slide guide, and (10) Li emitter. (Reprinted with permission from Ref [26], 2010, John Wiley and Sons)...

Similar research on paddy has been conducted by Laohavanich and Wongpichet (2008), who used a pilot-scale gas-fired IR dryer in batch mode. The drying chamber had a length of 1.2 m, a width of 0.9 m, and a height of 1.2 m. A slide-up door allowed insertion and removal of the sample. The gas-fired IR emitter was installed on the top panel, and the radiated power could be controlled by using a natural gas flow regulator. Burned gas and moist air in the chamber flowed out through a vent hole, which was fixed at the top of the chambet The emitter temperature was measured by thermocouples at the perforated plate of the emitter. 

With narrow tubes, this arrangement is no longer possible. However, the axial temperature profile may still be measured, preferably by means of a thermocouple sliding within a narrow capillary tube placed along the centre of the bed [ ]. 

In this experimental set up the liquid crystal is contained in a stainless-steel bellows which is placed inside a pressure-vessel-double-oven arrangement. The oven temperature is regulated by a proportional servomechanism using a sensor thermocouple. The Bridgman bellows with slide-wire technique [ 110] is used for the measurement of the sample volume. As the sample is compressed the flexible bellows contracts and moves a slide-wire under a contact. The fixed end does not move with respect to the contact. 

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