Temperature recorders

To obtain pure acetaldehyde, the product must be redistilled. Clean and dry the 200-250 ml. flask first used, immerse it in cold or ice water pour in the crude acetaldehyde rapidly, attach the fractionating column, etc. Immerse the receiver in crushed ice. Heat the flask gently in a water bath and adjust the temperature so that the aldehyde distils slowly and at a uniform temperature. The temperature recorded at the top of the column may depend partly upon the temperature of the laboratory, if this is above 21°. Pure acetaldehyde boils at 21°. 

Monomer emulsions ate prepared in separate stainless steel emulsification tanks that are usually equipped with a turbine agitator, manometer level gage, cooling cods, a sprayer inert gas, temperature recorder, mpture disk, flame arrester, and various nossles for charging the ingredients. Monomer emulsions are commonly fed continuously to the reactor throughout the polymerisation. 

Dry-heat sterilization is generally conducted at 160—170°C for >2 h. Specific exposures are dictated by the bioburden concentration and the temperature tolerance of the products under sterilization. At considerably higher temperatures, the required exposure times are much shorter. The effectiveness of any cycle type must be tested. For dry-heat sterilization, forced-air-type ovens are usually specified for better temperature distribution. Temperature-recording devices are recommended. 

Fig. 1. Flow diagram of production of sulfur dioxide from oleum 1, 30% oleum exchanger 2, SO vaporizer 3, reactor 4, coolant surge tank 5, coolant ckculatkig pump 6, coolant exchangers 7, sludge and acid pump 8, scmbber 9, SO2 cooler 10, gas cleaner 11, SO2 compressor 12, pulsation damper and 13, SO2 condenser. CM is the condensate FRC, flow recording controller PIC, pressure kidicatkig controller SM, steam TC, temperature recorder ...

Fig. 1. Fat sphtter. TRC, temperature recorder controller FLIC, Hquid level indicator controller PCV, pressure control valve and HCV, heat control valve.

Locate the RTDs at the likely hot spots, as at the joints of the busbars. Figure 14.2 illustrates the likely locations of the RTDs. The test may be carried out as noted earlier and temperature readings tabulated at 30-minute or l-hour intervals, whichever is more appropriate. The temperature rise, estimated with the highest temperature recorded by any of the RTDs, would refer to the ambient... 

If = temperature rise estimated at the test location 6 = ambient temperature at the test location 0i, = highest temperature recorded by any of the RTDs... 

Column Bottom Temperature. The bottom temperature is often controlled on the reboiler outlet line with a control valve in the heating medium line. The control point can also be on a bottom section tray. Care must be exercised in location of the temperature control point. It is recommended, especially for large columns, that a cascade arrangement be used. The recommended scheme has a complete flow recorder/controller (FRC) in the heating medium line including orifice and control valve. The set point of this FRC is manipulated by the temperature recorder/controller (TRC). This eliminates the TRC from manipulating the control valve directly (recall that temperature is the most difficult parameter to control). This makes for smoother control for normal operations. Also, it is handy for startup to be able to uncouple the TRC and run the reboiler on FRC for a period. 

Trouble (B) Temperature Recorders (Inoperable or Questionable Readings). 

A chemical reactor, being started, was filled with the reaction mixture from another reactor which was alic.uly on line. The panel operator increased the flow of fresh feed while watching an eye level temperature recorder He intended to start cooling water flow to the reactor when the temperature began to rise, but did not because the tempe.r.j, ure recorder was faulty, thus a runaway reaction. 

He did not notice the rise in temperature indicated on a six-point temperature recorder at a about three teet above itic llnoi. 

Dry bulb The air temperature recorded by a dry bulb thermometer, a sensory device excluding any effects of moisture or radiation. 

Globe The temperature recorded by a 100 mm black bulb (globe) thermometer. 

Resultant I he temperature recorded by a thermometer in the center of a 100 mm diameter blackened globe, corrections for the air velocity. 

Two furnaces were each fitted with a temperature recorder controller and high-temperature trip. The two recorders were side by side on the instrument panel in the control room, with the recorder for A furnace on the left (Figure 3-2). 

Unfortunately, there was a fault in the temperature recorder, and although the temperature actually rose, this was not indicated. Result a runaway reaction. 

A reactor was being started up. It was filled with the reaction mixture from another reactor which was already on line and the panel operator started to add fresh feed. He increased the flow gradually, at the same time watching the temperature on a recorder conveniently situated at eye level. He intended to start a flow of cooling water to the reaction cooler as soon as the temperature started to rise. Unfortunately, there was a fault in the temperature recorder and although the temperature actually rose, this was not recorded. As a result, a runaway reaction occurred. 

The rise in temperature was indicated on a six-point temperature recorder at a lower level on the panel, but the worker did not notice this. The check instrument was about three feet above the floor and a change in one reading on a six-point recorder in that position was not obvious unless someone was actually looking for it. 

The information may not be readily distinguishable either because it is too faint or because it may not be easily separated from other similar information. For example, a critical measurement on a multipoint temperature recorder may be lost in the surroimding clutter of irrelevant information. As discussed in the cognitive engineering approach described in Section 2.6, the worker may also ignore sources of information because of preconceptions that lead him or her to believe they are not significant. 

Temperature recording eoiitroller ajid temperature recorder, combined insti ument board mounted... 

Many oils possess the property of becoming solid at temperatures slightly below the ordinary, and a determination of the soliditying- or melting-points becomes an important criterion of purity in these cases. The melting-point is not usually the same as the solidifying-point, on account of the peculiar properties of bodies, included under the term superfusion, etc. In addition, the temperature recorded differs some-... 

Superheater elements are connected to inlet and outlet headers. The inlet header receives dry saturated steam from the steam drum of a watertube boiler or the shell of a horizontal boiler. This steam passes through the elements where its temperature is raised and to the outlet header which is connected to the services. A thermometer or temperature recorder is fitted to the outlet header. 

Figure 2.6. Temperature boundary layer and temperature changes in a tubular reactor, showing the graphs of temperature recorded at different positions on the tube.

Cycles established as statistically real are the familiar annual and diurnal radiation/temperature cycles, a quasibiennial (about every 2 years) fluctuation in various climatic elements, and the interannual variability of June rainfall in northern India. The first merely means that winters are cooler than summers and nights are cooler than days. Examples of the second cycle include Midwestern rainfall, a lengthy temperature record from central England, and winds over the western Paciflc and eastern Indian Ocean. According to Campbell et al (19), the third cycle may be a response to the monthly solar-lunar tide and its influence on the monsoon circulation. 

Jouzel, J., Lorius, J. R., Petit, C. et al. (1993). Vostok ice-core - a continuous isotope temperature record over the last climatic cycle (160000 years). Nature 329,403 08. 

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