Lyman discharge


Far-ultraviolet Microwave discharge in noble gases Lyman discharge LiF (or no windows) Grating Photomultiplier photodiode photographic plate  [c.60]

Use open vent or overflow line discharged to a safe location  [c.54]

Table 18.11 Protective characteristics of a gapless station class surge arrester for, (1) Line discharge class 4, and (2) Single impulse energy capability = 7 k.J/k.V, Table 18.11 Protective characteristics of a gapless station class surge arrester for, (1) Line discharge class 4, and (2) Single impulse energy capability = 7 k.J/k.V,
For example, for a line discharging a compressible fluid to atmosphere, the AP is the inlet gauge pressure or the difference between the absolute inlet pressure and atmospheric pressure absolute. When AP/Pi falls outside the limits of the K curves on the charts, sonic velocity occurs at the point of discharge or at some restriction within the pipe, and the limiting value for Y and AP must be determined from the tables on Figure 2-38A, and used in the velocity equation, Vj, above [3].  [c.114]

The pressure at the end of the return line, either atmospheric or of the vessel into which the line discharges  [c.332]

The mixture to be separated is dissolved in a suitable solvent and spotted on to a pencilled line at the bottom of the t.l.c. plate, ca. i o-i 5 cm. from the end. A suitable dropping tube may he made by drawing out the middle of a m.p. tube with a micro-burner and breaking the tube in the middle. The dropper is filled by capillary action and is discharged when the liquid at the tip drops on to the untouched absorbent surface the spot should be 2 5 mm. in diameter.  [c.58]

The mixture to be separated is dissolved in a suitable solvent and spotted on to a pencilled line at the bottom of the t.l.c. plate, ca. 1 0-1 5 cm. from the end. A suitable dropping tube may he made by drawing out the middle of a m.p. tube with a micro-burner and breaking the tube in the middle. The dropper is filled by capillary action and is discharged when the liquid at the tip drops on to the untouched absorbent surface the spot should be 2-5 mm. in diameter.  [c.58]

When an electron recombines with a positive ion, the incoming electron will attach at any of the vacant atomic orbitals, as illustrated by the three typical states (M,, Mj, M3 ). Other more excited states can be formed as the electron distribution in the newly formed neutral is disturbed (shaken up) by the added energy of the incoming electron. However, most of these states are unstable with respect to the ground-state atom, and the disturbed electrons drop down to more-stable orbitals until the ground state is reached. This increase in stability can only be achieved if energy is lost from the system. Thus, each time an electron drops to a lower orbital, a quantum of light is emitted with a wavelength that depends on the spacing between orbitals. Since many of these excited states are formed upon recombination and decay of the initial excited states, the spectrum of emitted light covers a wide range of wavelengths, viz., it is broadband emission. The light emitted from a gas discharge is a superposition of the line spectra arising from directly excited neutral atoms (Figure 6.3) and broadband spectra from electron/ion recombination. Some typical colors of emitted light are given in Table 6.1.  [c.32]

The diagrams depict some typical light outputs in relation to wavelength for various sources, (a) The sharp line (single wavelength) output from a laser or an atomic emission line, (b) The broader but still sharp wavelengths obtained by using interference filters, monochromators, and diffraction gratings or from molecular emission bands, (c) Broadband light output covering a wide range of wavelengths from such sources as the tungsten filament lamp, (d) A mixed output of a typical discharge lamp, having some intense narrow bands from atomic emission superimposed on broadband radiation from ion/electron recombination.  [c.120]

Sources of VUV radiation cause something of a problem. A deuterium discharge lamp emits down to 160 nm, a high-voltage spark discharge in helium produces radiation from 100 nm to 60 nm, and microwave-induced discharges in argon, krypton or xenon cover the range 200 nm to 105 nm. A much larger continuum range, from the visible down to about 30 nm, is provided by a Lyman source in which a large condenser is repetitively discharged through a low-pressure gas contained in a glass capillary. The most ideal source of VUV radiation is the synchrotron radiation source, which will be discussed in Section 8.1.1.  [c.63]

Until the advent of lasers the most intense monochromatic sources available were atomic emission sources from which an intense, discrete line in the visible or near-ultraviolet region was isolated by optical filtering if necessary. The most often used source of this kind was the mercury discharge lamp operating at the vapour pressure of mercury. Three of the most intense lines are at 253.7 nm (near-ultraviolet), 404.7 nm and 435.7 nm (both in the visible region). Although the line width is typically small the narrowest has a width of about 0.2 cm, which places a limit on the resolution which can be achieved.  [c.122]

It is possible to change the conditions in the helium discharge lamp so that the helium is ionized predominantly to He (He II). The radiation is due mainly to the n = 2 — n = transition of He II (analogous to the first member of the Lyman series of the hydrogen atom in Figure 1.1) at 30.4 nm with an energy of 40.81 cY A thin aluminium foil filter can be used to remove any He I radiation.  [c.292]

The lime, cooled somewhat by the entering air in the lower parts of the shaft kiln, is discharged intermittently and slaked to calcium hydroxide with  [c.523]

Synthetic Processes. Traditional Solvay plants produce large volumes of aqueous, chloride-containing waste which must be discharged. This fact, in addition to a noncompetitive cost position, is largely responsible for the demise of U.S. synthetic plants. In countries other than the United States, waste is sent to the ocean, rivers, or deep underground wells. The AC and NA coproduct processes produce less aqueous waste than the traditional Solvay and NA mono processes. Related environmental concerns are added whenever a plant complex includes lime quarries and ammonia-producing equipment.  [c.527]

Environmental and Safety Considerations. Soda ash and water washes are the primary sources of poUution from this process. These wastewaters may contain nitroglycerin, nitrates, and sulfates, and vary in pH from acid for the first wash after nitration to alkaline for the washes with soda ash. The process water is first sent through catch basins to remove nonsoluble nitroglycerin. The overflow may be discharged without further treatment or sent to percolation-evaporation ponds or earthen sumps. Acidic wastewater may be neutralized by passage through cmshed lime beds. Caustic soda and sodium sulfide may also be used to decompose and dissolve nitroglycerin in the effluent, foUowed by use of an activated sludge system as the secondary treatment. Other methods investigated include biodegradation of the nitroglycerin, reverse osmosis, absorption by polymeric resins, treatment with lime and caustic, and oxidation with ozone and permanganate.  [c.12]

The linters or wood pulp or mixtures of the two are passed through picking roUs to form a fluffy mass of material and dried at 80—100°C to less than 1% moisture content to minimize dilution of acid and the possibiUty of fires in the nitrator. A measured volume of mixed acid corresponding to exactly one dipping charge is drawn into a measuring tank and into the stainless steel nitrator where it is stirred at high speed. The weighed cellulose is rapidly transferred by an operator to the pot where it is immediately drawn below the surface of the acid. The nitration of cellulose occurs rapidly at first, and then slows down as the maximum nitrogen content is approached in 15—20 minutes. The contents of the pot are then discharged by gravity into the centrifuge where the nitrocellulose is separated from the spent nitrating acid. The nitrators are staggered so that nitrations are carried out in sequence by a small team of workers moving from one to the other as nitrations are completed. Eight to twelve centrifuges may be used for a line of nitrators.  [c.14]

With liquid bath quenching it is difficult to achieve an optically smooth surface unless all surface ripples are eliminated. In chill roU quenching, it is frequently necessary to pia the hot web to the dmm to eliminate air pockets, surface ripples, and other defects. As tine speeds increase this can become a controlling factor ia quality film production. The most common methods used to pin a web are to use an air knife ia close proximity to the emerging melt, or electrostatic pinning, where a high voltage field is established to force the web to the dmm. Vacuum assist under the web or hooded quench roUs may be used to control the atmosphere near the die and quench roU(s). Thicker webs or higher tine speeds may demand the use of multiple cooling roUs. The quenched film may be further processed (uni- or biaxially drawn, coated, or corona-discharge-treated to enhance adhesion). Generally the film is fed directly in-line to these other processes. If the film is suitable for use, it has the uneven edges trimmed off and is then wound iato master roUs for subsequent slitting iato narrower roUs, or is wound directly for shipment to customers.  [c.379]

The exterior of the kiln is heavy steel boiler plate, welded into sections the interior is lined with 15—24 cm refractory brick. A preheater rotary kiln system is shown in Figure 5. Kilns are installed at 3—5° inclination on foundation piers and revolve on tmnnions at 1—2 rpm. Limestone is fed into the elevated end of a kiln from the preheater or silos and is discharged as quicklime into the cooler at the lower end. Cooling air is induced into the cooler and from there to the calcining zone of the kiln next to the discharge end as secondary combustion air, providing heat recuperation. The hot air and gases are sucked countercurrent to the flow of kiln feed to the charging end where they provide recuperative heat for the preheater. Most U.S. rotaries are fired with pulverized coal, but are also adaptable to gas and oil firing. Only 10% of the kiln is filled with limestone—lime as the kiln feed tumbles gendy through the kiln. Kiln feed ranges in size from 0.625—6.25 cm, but multiple rotary kiln plants use more restricted gradations of 0.625—1.88 cm, 1.88—3.75 cm, etc.  [c.171]

The kiln discharge is leached with water, resulting in an impure lithium sulfate solution that contains the excess sulfuric acid and small amounts of aluminum, iron, and other alkaU sulfates. The excess sulfuric acid is neutralized with ground limestone. The slurry is then filtered to separate the ore residue, giving a mixed alkaU sulfate solution that is free of iron and aluminum but that is saturated with calcium sulfate. The solution also contains magnesium ions derived mainly from the limestone. Magnesium is precipitated using hydrated lime, followed by precipitation of calcium using soda ash or mother Hquor containing sodium carbonate generated in subsequent precipitation of by-product sodium sulfate decahydrate. After filtration, the solution is adjusted using sulfuric acid to pH 7—8, followed by concentration in a multiple-effect evaporator to alkah sulfate concentration of 350 g/L, 200—250 g/L of this being lithium sulfate. After a clarifying filtration, lithium carbonate is precipitated at 90—100°C with a 28 wt % soda ash solution. The precipitated lithium carbonate is centrifuged, washed, and dried. Approximately 15% of the lithium remains in the mother Hquor, along with residual sodium carbonate and large amounts of sodium sulfate. Cooling to about 0°C separates the greater part of the sodium sulfate as the decahydrate, which is centrifuged and converted to the anhydrous salt for by-product sale. The mother Hquor from the sodium sulfate decahydrate precipitation is recycled for lithium and soda ash values.  [c.222]

Pumps are usually located under the piperack. An open slot in the piperack has to be provided at the location of the pump suction and pump discharge lines so that the piping can make a straight mn down to the pump suction and then the discharge line can be mn directly back up to the piperack. Pumps commonly have an end suction and top discharge but they can also have a top suction and top discharge. The location of these nozzles on the pump can affect the piping configuration. The pump discharge line usually has some type of flow control valve that requires a piping drop from the piperack down to the control valve. The control loop usually has a control valve, a double-block valve around the control valve, and a hand bypass valve so that the valve can be replaced or repaired while the hand bypass is used for temporary control. Double-block and bypass valves should be located at an elevation where the valve and the controller can be accessed without a ladder.  [c.80]

Use of glow-discharge and the related, but geometrically distinct, hoUow-cathode sources involves plasma-induced sputtering and excitation (93). Such sources are commonly employed as sources of resonance-line emission in atomic absorption spectroscopy. The analyte is vaporized in a flame at 2000—3400 K. Absorption of the plasma source light in the flame indicates the presence and amount of specific elements (86).  [c.114]

Another popular type of on-line Ic/ms coupling is called the thermospray interface. In contrast to the particle beam approach, thermospray serves as a means for both droplet formation and ionization. The Ic effluent first enters the thermospray vaporizer probe where partial vaporization of the Hquid occurs to form droplets. As the Hquid droplets evaporate and decrease in size, ions present in the droplets ate ejected. These ionized molecules then diffuse through a chamber and exit through a small sampling cone into the high vacuum chamber. The ions exit, are directed into the quadmpole analyzer, and are detected in the electron multiplier. This technique provides soft ionization, ie, formation of molecular adduct ions having minimal fragmentation and stmctural information. Volatile buffers such as ammonium acetate ate used to enhance ionization and to provide a reagent for chemical ionization of the analyte. An electric discharge such as a Townsend discharge may be used, if desired, along with an electron filament to create additional fragmentation and to increase sensitivity. Generally, the filament-on mode produces more abundance than the filament-off mode. Temperature control of the vaporizer process is required for optimum sensitivity and reproducibiHty.  [c.403]

Chlorohydrin Process. The chlorohydrin process illustrated in Eigure 1 is fairly simple, requiring only two reaction steps, chlorohydrination and epoxidation, followed by product purification (109,110,112). Propylene gas and chlorine gas in about equimolar amounts are mixed with an excess of water to generate propylene chlorohydrin and a small amount of chlorinated organic coproducts, chiefly 1,2-dichloropropane (109). Epoxidation, also called saponification or dehydrochlorination, is accompHshed by treatment of the chlorohydrin solution with caustic soda or milk of lime (aqueous calcium hydroxide). Propylene oxide and other organics are steam-stripped from the resulting sodium chloride or calcium chloride brine. The brine is treated, usually by biological oxidation, to reduce organic content prior to discharge. The propylene oxide is further purified to sales specifications by removal of lights and heavies via distillation.  [c.136]

Effluent W stew ter Treatment. The volume of water effluent is about 40 times the volume of propylene oxide produced in the chlorohydrin process, representing a significant concern for proper disposal or reuse (112). The options for treatment of the water effluent from the epoxidation process depend on the alkaH used. Use of lime in epoxidation results in a calcium chloride brine (4—6 wt %) that has Htde commercial value and is, therefore, discharged. Use of caustic soda in epoxidation results in a sodium chloride brine that can either be discharged or recycled to a chloralkali electrolysis unit to generate chlorine and caustic (111). The effluent is treated biologically to reduce organic content prior to discharge or recycle (125,126).  [c.137]

Pipes and Pipelines. Samples may be withdrawn both from closed pipe cross sections and from the outfall of open pipes. The simplest system for the former consists of an in-pipe sampling probe as shown in Figure 11 (18). In the chemical industry, many pipe samples are taken from organic Hquids, which may be toxic, highly reactive, and flammable. The amount of sample taken should be minimised in order to reduce worker exposure and sample disposal problems. Adequate ventilation must be provided because the vapors from many Hquids are more dangerous than the Hquids. Splash guards are necessary when sampling corrosive and toxic Hquids. For these appHcations in-line samplers are preferred. These trap and isolate a predeterrnined, precise volume of Hquid from the line and deHver it to a closed container. Samplers can be installed on either side of the suction or discharge side of pumps. Typical devices include sampling plugs, multiport valves, and pneumatic samplers (19). The sampling plug is usually inserted in a bypass line as shown in Figure 12. The plug has both sample and vent connections. When open, the Hquid pumped through the bypass line passes through the plug and can be returned to the line. When closed, a small constant volume of Hquid is trapped in the plug and, on rotation of the tap, is drained into the sample bottle while the tap is simultaneously vented (19). If exposure to air can cause a problem in the process, the valve can be vented with nitrogen and then closed before the Hquid in the bypass line is returned to the process. Mainstream sampling is usually performed with a sharp-edged probe facing directly into the flow at some preset point. In pressurized systems, sampling sites can rarely be statistically designed with regard to location and once installed are difficult to relocate. Care has to be taken when discharging plug samplers using pressurized systems in order to prevent the Hquid venting through the valve connections (19). Sometimes a safety valve is inserted in the bypass to prevent blockage of the pump discharge.  [c.303]

Larger sample sizes can be obtained using multiport valves (19). During normal operation, the Hquid flows through the valves in a bypass line. Often two values are employed. A sample is extracted by turning both valves simultaneously, first to isolate the sample and then to let it discharge into the sample botde. This is best achieved by gear-and-linkage devices, which mechanically link the two valves. Failure to do this simultaneously can result in the full line pressure being vented through the sample line (19). Thus this type of sampler presents potential hazards when used for high pressure systems.  [c.303]

Sampling from pneumatic conveyors parallels gas sampling. The exception is that soflds loadings can be as high as 50 kg of soHds per kg of gas. Commercially available samplers extract particles directly from a transport line. Fixed position samplers are mounted directly on the pneumatic conveyor pipe. Devices are available which extract samples from the product stream by the projection of a sample tube iato the flow. Particles impact on the tube and fill the open cavity. The tube is then withdrawn, and an internal screw discharges the collected material (20). In another model, the RX Sampler (manufactured by Gustafson) (29), samples are withdrawn usiag compressed air.  [c.306]

Fig. 4. Drainage of salt crystals in a cylindrical screen pusher-discharge centrifuge (8), where the cake thickness is 3.3 cm, the centrifugal field = 320 U, and the crystals 14 wt % <250 p.m. ( ) Represents moisture in the discharge cake, and (° ) moisture in the cake by material balance with drainage flows line A Fig. 4. Drainage of salt crystals in a cylindrical screen pusher-discharge centrifuge (8), where the cake thickness is 3.3 cm, the centrifugal field = 320 U, and the crystals 14 wt % <250 p.m. ( ) Represents moisture in the discharge cake, and (° ) moisture in the cake by material balance with drainage flows line A
Other successful actuators have been developed for various domestic safety devices. One such device is a shape-memory-actuated valve that fits in line with a bathroom sink, tub, or shower, and in the event that through some system imbalance or malfunction the water discharge approaches the temperature that would cause scalding, the valve automatically shuts off the flow and does not allow water flow to resume until the temperature is safe. A similar thermally triggered valve has been developed for shutting off the flow in industrial gas or fluid lines in the event of an excessive temperature or a fire. Shape-memory actuators are also candidate actuators to replace the glass bulb or fusible link in overhead fire extinguisher systems. Regulations stress the protection of human life, requiring that the sprinkler actuation speed be decreased to 14 s, weU within the capabiHty of an inexpensive SMA device but more difficult to achieve in the conventional trip devices.  [c.464]

The chlorine emerges through the nickel dome, H, and is removed through the chlorine line, I, to a header (see Alkali and chlorine products). Sodium, J, is channeled to a riser pipe, K, which leads to a discharge point above the cell wall. The difference in level between the overflowing sodium and the cell bath is due to the roughly 2 1 density ratio of the fused bath and Hquid sodium. The upper end of the riser pipe is fitted with fins that cool the sodium and thereby precipitate dissolved calcium. The sodium, still containing some calcium, electrolyte, and oxide, overflows into a receiver, L. The calcium precipitated in the riser pipe tends to adhere to the wall from which location it is dislodged by the scraper, M, and returned to the base of the riser. The cell is fitted with a smoke-collection cover to collect particulate emissions and to protect the operators. A small area is left uncovered for visual observation, bath-level regulation, and salt-bath agitation and salt feed. Fine, dry crystalline salt is fed to the bath through a feed chute from a salt system conveyor (not shown).  [c.166]

For quantitative analysis, the resolution of the spectral analyzer must be significantly narrower than the absorption lines, which are - 0.002 nm at 400 nm for Af = 50 amu at 2500°C (eq. 4). This is unachievable with most spectrophotometers. Instead, narrow-line sources specific for each element are employed. These are usually hoUow-cathode lamps, in which a cylindrical cathode composed of (or lined with) the element of interest is bombarded with inert gas cations produced in a discharge. Atoms sputtered from the cathode are excited by coUisions in the lamp atmosphere and then decay, emitting very narrow characteristic lines. More recendy semiconductor diode arrays have been used for AAS (168) (see Semiconductors).  [c.317]

Many techniques exist for volatilizing and exciting samples. Flame emission spectroscopy uses much the same source apparatus as AAS, but records the emission lines that in the latter method must be minimized. Line interference is more serious than for absorption, and chemiluminescence in the flame may be a problem. AES is most appropriate for alkaU metals, for which it offers the best detectabiUty, alkaline earths, rare earths, and trace metals. Electrical discharge methods include high temperature (4000—6000°C) a-c or d-c arc and a-c spark discharges in air between high purity graphite electrodes, one of which holds the sample. These were long the principal AES techniques, but suffer from problems with reproducibiUty and interferences. The most notable interference is the cyanogen molecular emission spectmm (360—420 nm). Arc and spark emission were stiU used for rapid semiquantitative analysis of ferrous metals and other industrial samples as of this writing.  [c.317]

Slag-forming fluxes, chiefly burnt lime, fluorspar, and mill scale (iron oxides), are added in controlled amounts from an overhead storage system shortly before or after the oxygen jet is started. These materials, which produce a slag of the proper basicity and fluidity, are added through a chute built into the side of a water-cooled hood positioned over the mouth of the furnace. This hood collects the gases and the dense reddish brown fume emitted by the furnace during blowing, and conducts them to a cleaning system where the soflds are removed from the effluent gas before it is discharged to the atmosphere. Without access to sintering machines, which are largely closed by environmental constraints but used to be valuable faciUties to recycle dusts of various types, easy disposal is a problem (12).  [c.377]

Grounding. Use of a grounded bar, rod, or roU to discharge static charge buildup is effective for conductive materials which contain a charge. Grounding is ineffective for insulators since the electrons on an insulator are not sufftciendy mobile to travel to ground. For partially conductive materials, grounding can be somewhat effective for the area of the object in contact with the ground. Grounding of a partially conductive material is best attempted by contacting the entire surface of the object, eg, using a string of copper tinsel stretched across a roU of paper on a computer printer. loni tion. If a charge is located on an insulator, there is in principle no way by which the charge may be removed. If, however, the charged insulator is completely surrounded by a conducting duid in contact with all points of the surface, the charge or the field from the charge may be neutralized by oppositely charged ions being attracted to the insulator. Although this scenario in principle could be estabUshed by using a conducting Hquid, the only practical solution is to surround the charged body with ionized air (53).  [c.289]

Furnace Operation. A crew of five is typically needed to operate a large carbide furnace installation one person for raw material control, two for furnace operation, and two for tapping. The lime and coke are weighed separately by automatic weigh scales that discharge onto conveyors feeding the furnace area. The charge is deflvered to the furnace continuously by feed conveyors that automatically maintain the charge levels in the feed pipes. As the  [c.460]

Line Line discharge Surge Virniul Appro.x.  [c.613]

These are the line discharge lest values to icsi an arrester, as recommended by lEC and have been considered here lor the purpose of selection of an arrester. Refer to E.xample I8..S.  [c.613]

A gas discharge in GDC is initiated by pulse X-ray or high-energy bremsstrahlung radiation Being applied to electrodes the pulses of high voltage from the areas of primary gas ionization are developing into electron avalanches, transforming under certain conditions into streamers, which lead to image amplification. Along with ionization by an electron impact the process of resonant atom excitation also proceeds in pure inert gases During numerical simulation of the process of a gas discharge development in GDC it was established, that account for atom photo-ionization by resonant photons, propagating on line wings, allows to explain the mechanism of a cathode-directed streamer in pure Xe, and as a whole it increases a gas amplification factor. A maximum factor of gas amplification in our GDC reaches lO -lO. The presence of molecular additives stabilises a gas discharge at the expense of energy exchange between excited atom states of an inert gas and oscillating levels of an additive molecules.  [c.539]

Figure C3.1.4. Schematic measurement traces depicting different probe strategies for transient spectroscopy and tlieir typical time scales. Each panel represents the intensity of a probe beam against time. The small Gaussian at tire bottom left of each panel represents tire excitation (pump) pulse, defining tire zero of time, (a) Strategy using a constant, cw light source as probe. The top line represents tire probe light in tire absence of laser pump excitation and tire curved line represents a changing intensity after excitation of tire sample. Time scales milliseconds to seconds, (b) A cw arc lamp as in panel (a) augmented by a capacitive discharge across tire arc to enlrance intensity by a factor of 10-100. Time scales microseconds to milliseconds, (c) A pulsed flashlamp is an alternative to tire pulsed cw lamp in panel (b) tliat produces high power but low total energy from tire probe light source, allowing for measurements on a faster time scale nanoseconds to microseconds, (d) Pulsed lasers used for botli pump and probe sources. Note tliat tire pump pulse (left) is shown enlarged to emphasize tire fact tliat tire pump pulse must be much larger tlian tire probe pulse. The probe pulse decreases in magnitude when tire pump pulse excites tire sample, creating a transient absorjrtion. The probe pulse in tire presence of tire pump pulse is drawn wider only to make it easier to see in tire figure. Time scales nanoseconds to seconds, (e) Witli gated multichannel detection, tire flashlamp probe in panel (c) is observed at a particular time delay after pump excitation, ratlier tlian monitored as a function of time as in single-wavelengtli detection. The probe pulse is diminished by tire presence of transient absorjrtion created by pump excitation, as measured by tire spectra of tire probe witlr and without pump sampled over a small range of delay times indicated by tire gate pulse . The probe pulse and detector gate are kept overlapped as tlieir joint time delay is varied to yield spectra as a function of time on time scales from nanoseconds to seconds. Figure C3.1.4. Schematic measurement traces depicting different probe strategies for transient spectroscopy and tlieir typical time scales. Each panel represents the intensity of a probe beam against time. The small Gaussian at tire bottom left of each panel represents tire excitation (pump) pulse, defining tire zero of time, (a) Strategy using a constant, cw light source as probe. The top line represents tire probe light in tire absence of laser pump excitation and tire curved line represents a changing intensity after excitation of tire sample. Time scales milliseconds to seconds, (b) A cw arc lamp as in panel (a) augmented by a capacitive discharge across tire arc to enlrance intensity by a factor of 10-100. Time scales microseconds to milliseconds, (c) A pulsed flashlamp is an alternative to tire pulsed cw lamp in panel (b) tliat produces high power but low total energy from tire probe light source, allowing for measurements on a faster time scale nanoseconds to microseconds, (d) Pulsed lasers used for botli pump and probe sources. Note tliat tire pump pulse (left) is shown enlarged to emphasize tire fact tliat tire pump pulse must be much larger tlian tire probe pulse. The probe pulse decreases in magnitude when tire pump pulse excites tire sample, creating a transient absorjrtion. The probe pulse in tire presence of tire pump pulse is drawn wider only to make it easier to see in tire figure. Time scales nanoseconds to seconds, (e) Witli gated multichannel detection, tire flashlamp probe in panel (c) is observed at a particular time delay after pump excitation, ratlier tlian monitored as a function of time as in single-wavelengtli detection. The probe pulse is diminished by tire presence of transient absorjrtion created by pump excitation, as measured by tire spectra of tire probe witlr and without pump sampled over a small range of delay times indicated by tire gate pulse . The probe pulse and detector gate are kept overlapped as tlieir joint time delay is varied to yield spectra as a function of time on time scales from nanoseconds to seconds.
A more constrained opportunity for nitrate bioremediation arose at the US-DoE Weldon Spring Site near St. Louis, Missouri. This site had been a uranium and thorium processing faciUty, and treatment of the metal had involved nitric acid. The wastestream, known as raffinate, was discharged to surface inpoundments and neutralized with lime to precipitate the metals. Two pits had nitrate levels that requited treatment before discharge, but heavy rains in 1993 threatened to cause the pits to overflow. Bioremediation by the addition of calcium acetate as a carbon source successfully treated more than 19 million liters of water at a reasonable cost (75).  [c.36]

As the difference between the suction and discharge pressure increased, it became necessary to remove the pressure fluctuations from the area of the cross-bores and several ways of doing this have been described (168). In the arrangement shown in Figure 36b, the suction and discharge valves are arranged in line and the entire valve body is subjected to suction pressure on the outside only the gas passage leading to the discharge valve is subject to cychc pressure. Separation of suction and deflvery pressure is assured by the sealing ring and the entire valve is pressed on the end of the cylinder liner by the difference of pressure and the precompressed belviUe washers. The components of this valve assembly can be autofrettaged to increase their fatigue resistance. Other manufacturers subject the outside of their axial valves to discharge pressure, which gives added strength, and may use multipoppet valves or plate valves instead of single poppet valves. Figure 36b, shows an axial plate valve in which the discharge pressure acts on the outside surface of the components such a valve might be used in the pressure wrapped cylinder shown in Figure 34.  [c.103]

Therma.1 Requirements. To produce a ton of lime theoretically requires 1.79 and 1.90 t of high calcium and dolomitic stone, respectively. Practically, at least 2 t of stone is needed to produce 1 t of lime, because some stone is lost as dust during the process. To heat the stone to the dissociation point, ca 1.70 GJ/t (1.46 x 10 Btu/short ton) for high calcium and 1.45 GJ/t (1.25 x 10 Btu/short ton) are required for dolomitic quicklimes. However, temperature, usually a higher than the theoretical one, must be maintained until dissociation is terminated. This additional thermal requirement is estimated at 3.22 and 3.02 GJ/t (2.77 and 2.60 x 10 Btu/short ton) for high calcium and dolomitic stones, respectively. In addition, some heatloss is inevitable in lime manufacture, such as heat of evaporation of moist limestone and/or coal, radiation and convection through the kiln stmcture, retention in the discharged lime, exhaust gases, and incombustible dusts. The thermal efficiency is given as  [c.171]

The use of rare-earth phosphors in fluorescent lamps has also resulted in improved maintenance as compared to the halophosphate phosphor throughout the life of a lamp. Phosphor lumen maintenance is determined by the resistance of the material to higher energy 185-nm radiation from the mercury discharge and resistance to mercury ion bombardment. The compact fluorescent lamps which have gained popularity in the 1990s owe their existence to the abiUty of these phosphors to resist degradation even under high loading over the life of the lamp.  [c.289]

Another big advance in the appHcation of ms in biotechnology was the development of atmospheric pressure ionization (API) techniques. There are three variants of API sources, a heated nebulizer plus a corona discharge for ionization (APCl) (51), electrospray (ESI) (52), and ion spray (53). In the APCl interface, the Ic eluent is converted into droplets by pneumatic nebulization, and then a sheath gas sweeps the droplets through a heated tube that vaporizes the solvent and analyte. The corona discharge ionizes solvent molecules, which protonate the analyte. Ions transfer into the mass spectrometer through a transfer line which is cryopumped, to keep a reasonable source pressure.  [c.547]

In clarifying operations, the conveyor discharge centrifuge recovers many types of crystals, meal from fish press hquor, and polymers, such as poly(vinyl chloride) and polyolefins. It is also used to dewater coal (24) and to concentrate sohds from flue gas desulfurization sludges. Vertical designs, vapor-tight or under pressure, are apphed to terephthahe acid, polypropylene, and catalyst recovery. Classification iacludes separation of particles over 2 p.m from kaolin coating clay, and of particles over about 5 pm ia the mill discharge of grouad Ti02 selective recovery of calcium carboaate from lime-treated waste sludges permits calcining and recycling of the lime without an overwhelming recycle load of iaert material. The conveyor centrifuge is frequently used to rough out medium and coarse sohds before a second separation stage such as a disk centrifuge handling refinery sludges.  [c.412]

The gravity-displacement-type autoclave rehes on the relative nonmiscibility of steam and air to allow the steam that enters to rise to the top of the chamber and fill it. The air is pushed out through the steam-discharge line located at the bottom of the chamber. Gravity-displacement autoclaves are utilized for the sterilization of Hquids and for unwrapped nonhoUow medical instmments at 134°C.  [c.408]


See pages that mention the term Lyman discharge : [c.614]    [c.3001]    [c.172]    [c.245]   
Modern spectroscopy (2004) -- [ c.63 ]