Auxiliary heating

The need for auxiliary heating is another factor that must be carefully evaluated. Due to the nature of the thermodynamic process, the gas discharging from an expander is at a much lower temperature than gas discharging from a regulator station operating within the same pressure bounds. If temperatures downstream of the expander are allowed to drop too low, potential problems may arise, such as hydrate formation and material compatibility.  [c.479]

There are several methods available to avoid problems with low discharge temperature. One solution is auxiliary heating. The gas can be heated upstream of the expander this is called pre-heating. The gas can also be heated downstream of the expander, known as post-heating.  [c.479]

Once again, whether or not to use auxiliary heating is an economic decision. The heating allows more energy to be extracted from the gas stream, but the cost of the heat source or fuel must be subtracted from the value of the energy recovered. If the facility is to qualify under U.S. governmental regulations, auxiliary heating must be included when calculating the primary energy source.  [c.480]

Conduction furnaces ate of three general types. One has a pot or cmcible with suitable exterior insulation. Sheathed resistance elements are inside the pot which contains molten lead or another low melting metal. The molten metal can be the conductive medium that transfers heat to the work immersed in it, or the molten metal may be the work. Such furnaces ate often used to supply molten-type metal, lead, zinc, etc. As the molten metal is removed, bars of the metal are added for melting. The initial charge of soHd metal does not provide good surface contact with the heating elements and, because of this, the metal around the heating elements is often melted initially with a torch or other auxiliary heat during start up.  [c.137]

Several configurations of forced circulation evaporators are shown in Figure 2. The most common arrangement is shown in Figure 2a having an external vertical single-pass heater and a tangential inlet to the body. Figure 2b shows the Oslo type of crystallizing evaporator in which the crystals ate retained in a duidized bed below the dash chamber. Because it is not always necessary to avoid boiling in the heating element, the element can project into the vapor head, as shown in Figure 2c. Auxiliaries shown in Figure 2 are not exclusive to each type of unit. Entrainment separators shown are top- and bottom-oudet centrifugal type and knit-mesh, respectively. The evaporator in Figure 2a includes a swid breaker over the circulating pump inlet to reduce vortex losses in the vapor head and an elutriation leg to size, wash, and cool a crystallized product with part or all of the feed. In all cases, the steam inlet and vent outiet on the heat exchanger are placed so as to provide a positive dow path over the heating surface between the two. Forced circulation evaporators can be built for high single-unit capacities, having bodies as large as 15 m in diameter. The circulating pump is usually the limiting factor and it is not unusual to provide a single large body with as many as four or five separate heaters and circulating systems. For extreme fouling or salting conditions, the individual heaters can be arranged to be valved from the evaporator and cleaned without internipting system operation.  [c.473]

Vacuum-shelf dryers require auxiliary stream jets or other vacuum-producing devices, intercondensers for vapor removal, and occasionally wet scrubbers or (heated) bag-type dust collectors.  [c.1190]

Association (United States) calciilates efficiencies based on the lower heating value (LHV) for gas fuels and the higher heating value for oil fuels. It is general prac tice to report gas-engine performance in terms of British thermal units per horsepower-hour (LHV) and oil-engine performance in terms of pounds of fuel consumed per horsepower-hour. For electric power plants, fuel consumption is reported in terms of kilowatts. Auxiliaries included with engine-efficiency calculations vaiy with industry practice.  [c.2494]

The purpose of this standard is to provide guidance to facilitate the preparation of gas turbine procurement specifications. It is intended for use with gas turbines for industrial, marine, and electric power applications. The standard also covers auxiliary systems such as lubrication, cooling, fuel (but not its control), atomizing, starting, heating-ventilating, fire protection, cleaning, inlet, exhaust, enclosures, couplings, gears, piping, mounting, painting, and water and steam injection.  [c.153]

RTO/RCO and Rotor/Concentrator systems are typically higher in capital costs, but the operating cost savings on high volume, low concentration streams make these technologies attractive. Subsequently the capital and operating cost of the equipment and the cost of the installation of that equipment is related to the sizing. Since oxidation equipment requires fuel and electricity, the operating costs will also depend on the hours or operation per day, per week, and per year. In addition, the costs depend on the quantity of organics that need to be processed, in pounds per hour (Ib/hr), or in parts per millions by volume (ppmv). A critical consideration is whether the organic loading is steady state or if it has peaks or spikes. Since all oxidation equipment has to operate at an elevated temperature, it is necessary to know the type of auxiliary energy of fuel available. All oxidizers can operate on electric heating, natural gas, or LPG, whereas thermal oxidizer can operate with sulfur based fuels such as number two or number six fuel oil. Electric heat is only suitable for small air flows otherwise it is too costly. No thermal oxidizer should  [c.475]

Comments on the temperature of the auxiliary air are common. Auxiliary cupboards were first introduced to save energy and unconditioned outside air has often been used for the auxiliary supply air. This is usually not acceptable because unconditioned supply air will be too cold during the heating season for a person to work at the hood. It may also be too hot during the cooling season. Today, most auxiliary air systems operate at temperatures close to room temperature.  [c.994]

Heating, ventilation, and air conditioning (HVAC) system controls are the link between varying energy demands on a building s primary and secondary systems and the approximately uniform demands for indoor environmental conditions. Without a properly functioning control system, the most expensive, most thoroughly designed HVAC system will be a failure. It simply will not control indoor conditions to provide comfort. The main controlled variable in buildings is zone temperature. The control of zone temperature involves many other types of control within the primary and secondary HVAC systems, including boiler and chiller control, pump and fan control, liquid and air flow control, humidity control, and auxiliary system control subsystems. There are two fundamentally different control approaches— pneumatic and electronic. Various kinds of sensors, controllers, and actuators are used for principal HVAC applications.  [c.302]

Alternatively, the option that a steam plant offers of the provision of process steam coupled with power generation may be the key element in the selection of generating plant. The turbo-generators and their auxiliaries for use in such applications tend therefore to be relatively unsophisticated, with no feed heating, except for probably the provision of a deaerator. Again, in the turbine itself, machine efficiency tends to be sacrificed for robustness and the ability to accommodate varying load conditions.  [c.202]

In any event, die economics for San Diego Gas Electric s expander facility were fairly straightforward. There was no need for auxiliary heating, so die most difficult and critical decision concerned die capacity of die generator being installed. This capacity was finally determined based on historical flow data and a desire to maximize die amount of time die unit was operating. Because diis was a research project, die need to gadier operating experience was weighted heavily when selecting die size unit to install.  [c.480]

Precision combustion measurements are primarily made to detennine enthalpies of fonnation. Since the combustion occurs at constant volume, the value detennined is the energy change AJJ. The enthalpy of combustion A //can be calculated from A U, provided that the change in the pressure within the calorimeter is known. This change can be calculated from the change in the number of moles in the gas phase and assuming ideal gas behaviour. Enthalpies of fonnation of compounds that do not readily bum hr oxygen can often be detennined by combusting in fluorine and the enthalpy of fonnation of volatile substances can be detennined using flame calorimetry. For compounds that only combust at an appreciable rate at high temperature, such as zhconium in chlorine, the teclmique of hot-zone calorimetry is used. In this method one heats the sample only very rapidly with a known amount of energy until it reaches a temperature where combustion will occur. Alternatively, a well characterized material such as benzoic acid can be used as an auxiliary material which, when it bums, raises the temperahire sufficiently for the material to combust. These methods have been discussed in detail [2, 3 and 4].  [c.1910]

Both the shell and the rotor carry steam as a heating medium to effect indirect transfer as the burden briefly contacts those surfaces rather than from the transport air, as is normally the case. The rotor turns slowly (1 to 10 r/min) to control, by deflectors, product distribution and prevent caking on walls. The carrier gas can be inert, as nitrogen, and also recycled through appropriate auxiliaries for solvent recovery. Apphcation is limited to burdens that (1) are fine and uniformly grained for the pneumatic transport, (2) dry very fast, and (3) have very little, if any, sticking or decomposition characteristics. Feeds can carry 5 to 100 percent moisture (dry basis) and discharge at 0.1 to 2 percent. Wall temperatures range from 100 to 170°C (212 to 340°F) for steam and lower for a hot-water-heat source. Pressure drops are in order of 500 to 1500 mmH20 (20 to 60 inH20). Steam consumption approaches that of a contractive-mechanism dryer down to a low value of 2.9 kg steam/kg water (2.9 lb steam/lb water). Available burden capacities are 91 to 5900 kg/h (200 to 13,000 Ib/h).  [c.1097]

Petjormance and Cost Data for Direct-Heat Potary Dryers Table 12-18 gives estimating-price data for direci rotary dryers employing steam-heated air. Higher-temperature operations requiring combustion chambers and fuel burners will cost more. The total installed cost of rotary dryers including instrumentation, auxiliaries, allocated building space, etc., will run from 150 to 300 percent of the purchase cost. Simple erection costs average 10 to 20 percent of the purchase cost.  [c.1204]

Figure 16-49 [Engineering Data Book, 10th ed., Gas Processors Slippers Association, Tulsa, 1988, Sec. 20, p. 22] depicts the flow scheme for a typical two-bed TSA dryer system showing the auxiliary equipment associated with regeneration. Some of the diy product gas is externally heated and used couutercurreutly to heat and desorb water from the adsorber not currently drying feed. The wet, spent regeneration gas is cooled the water is condensed out and the gas is recycled to feed for recovery. Figure 16-49 [Engineering Data Book, 10th ed., Gas Processors Slippers Association, Tulsa, 1988, Sec. 20, p. 22] depicts the flow scheme for a typical two-bed TSA dryer system showing the auxiliary equipment associated with regeneration. Some of the diy product gas is externally heated and used couutercurreutly to heat and desorb water from the adsorber not currently drying feed. The wet, spent regeneration gas is cooled the water is condensed out and the gas is recycled to feed for recovery.
Although most of the purification equipment in a large biotechnological facdoiy is the same as that used throughout the (memical process industries, there are fewer separations in which the product reaches elevated temperatures. Most biochemicals are destroyed if heated. Recoveiy of produces from the bioprocess fluid can be more difficult and expensive than all of the previous steps. The ratio of recoveiy costs to cost of creating the product can range from about one to more than ten because the investment for the recoveiy facilities may be several times that for the fermenter vessels and their auxiliary equipment. As much as 60 percent of the fixed costs of fermentation plants for organic acids or amino acids is attributable to the recovery section. The costs for recovery of proteins based on recombinant DNA techniques are particularly high.  [c.2143]

Lube oil units are typieally available in two versions the manu-faeturer s standard or in aeeordanee with API Standard 614. The major eomponents of a unit are the oil tank, auxiliary oil pump, double filter and, seleetively, one or two oil eoolers. All eomponents of the smaller units are mounted on a eommon bedplate, separated from the other eomponents. The oil ean be heated by an eleetrieal or steam-powered heating unit. The neeessary instrumentation is a standard supply item and, if requested, the switehes and motors ean be prewired. The main and auxiliary oil pumps are driven by different types of drivers (e.g., one by an eleetrie motor and the other by either a small steam turbine or by direet eonneetion to the shaft end of a major maehine easing in the turbotrain).  [c.129]

Diastereoselective conjugate additions to chital Michael acceptors in which the part initially heating the chital information is removable ii.e., a chital auxiliary) provides a means to synthesize enantiomerlcally pure conjugate adducts. Chital auxiliaries iduould ideally he readily available in both enantiomeric fornts. Tliey should  [c.202]

See pages that mention the term Auxiliary heating : [c.113]    [c.66]    [c.1096]    [c.81]   
Turboexpanders and Process Applications (0) -- [ c.479 , c.480 ]