Optimum efficiency

Control Devices. Control devices have advanced from manual control to sophisticated computet-assisted operation. Radiation pyrometers in conjunction with thermocouples monitor furnace temperatures at several locations (see Temperature measurement). Batch tilting is usually automatically controlled. Combustion air and fuel are metered and controlled for optimum efficiency. For regeneration-type units, furnace reversal also operates on a timed program. Data acquisition and digital display of operating parameters are part of a supervisory control system. The grouping of display information at the control center is typical of modem furnaces. 

The double-inclined kiln calcines even smaller si2ed stone of 1.88—3.75 cm and at reduced capacity with stone of only 0.63 cm minimum si2e. Most of these kilns operate using gaseous or oil fuels, including propane. An exception is the double-inclined kiln, which appears to operate at optimum efficiency with a mixture of fuel, ie, 60—75% natural gas or oil and 40—25% coke, although it can operate on 100% gas or oil. 

For the preliminary estimate of the expected efficiency of expansion turbines, in most cases it is sufficient to neglect Reynolds number effects (Rg > 10 ) and use the efficiency and specific speed correlations shown in Figure 2-12 for partial admission axial impulse, reaction radial inflow and full admission impulse and reaction axial turbines. Due to the economic advantage of the radial turbine, die radial inflow turbine is die best selection when operating in die specific speed range 20 < Nj < 140, whereby die optimum efficiency will be achieved at N, = 80. 

Figure 4-70 shows a four-body TPG train (string). As before, the expander supplies power to the generator. The steam turbine supplies power to the generator, provides startup power, and provides control for synchronization. The generator provides electricity, and the gear is used to allow the expander and steam turbine to operate at near optimum efficiency with the generator at its desired speed. 

Figure 4-110 depicts an efficiency curve versus velocity ratio for a reaction-type expander. The optimum efficiency will occur at a velocity ratio of. 63. For a velocity ratio considerable greater or less than. 63 a significant efficiency penalty can be expected. Considering the effects on the parameters mentioned above, it is easy to see the importance the velocity ratio has on the performance of the expander. 

Any effect of Mach number is experienced by rotor and stator equally and thus neither (or both) are limiting, and this Mach number will be lower than for other degrees of reaction under the conditions stated. If equal lift and drag are assumed in both rotor and stator, then optimum efficiency is obtained with R = 0.5 and VJu = 0.5. Although the latter is not always true, it does provide a useful criterion. Furthermore, the blade angles are similar in rotor and stator, which may be an advantage in the... 

The principle significance of specific speed for the process engineer is to evaluate the expected performance of a second pump in a particular manufacturer s series while basing it on the known performance (or curve) at the point of optimum efficiency of a first and different size pump. In effect the performance of any impeller of a manufacturer s homologous series can be estimated from the known performance of any other impeller in the series, at the point of optimum efficiency. Figures 3-48 and 3-49 represent the standardized conditions of essentially all pump manufacturers. 

Combustion equipment can be set to give optimum efficiency at the time of commissioning but this condition will not be maintained. Wear and tear on control valves, partial blockage of filters, sooting of surfaces, etc. will all cause a fall in efficiency. To counter this, regular maintenance is desirable, and must include routine flue analysis and burner adjustment. 

Most combustion equipment is not controlled by means of a feedback from flue gas analysis but is preset at the time of commissioning and preferably checked and reset at intervals as part of a planned maintenance schedule. It is difficult to set the burner for optimum efficiency at all firing rates and some compromise is necessary, depending on the control valves used and the control mode (e.g. on/off, fully modulating, etc.). 

Combustion equipment, when first commissioned, can be set to operate at its optimum efficiency. With time, however, there will be a deterioration due to blockage of air filters and breather holes, wear in valve linkages, etc. Such changes may have safety implications if gas-rich firing is a consequence. 

For optimum efficiency of usage, steam should be employed at its highest energy level, consistent with each particular application need. And, as noted above, additional fuel costs to supply steam at higher rather than lower pressures are small compared with the delivered energy benefits. Ultimately, therefore, higher pressures produce overall financial savings and maximize efficiencies. 

Electrode boilers produce hot water or steam (generally saturated steam) by conducting current through the BW. The water provides resistance, which causes heat to be generated when electrical current flows from one electrode to another. As a consequence, the electrical conductivity of the water is a primary factor in the satisfactory operation of these boilers. Other aspects of water treatment control (such as alkalinity levels, oxygen content, and foam control) and maintenance also must be considered if optimum efficiency is to be obtained. 

Aceves-Saborio, S., Nakamura, H., and Reistad, G.M., 1994, Optimum efficiencies and phase change temperatures in latent heat storage systems, ASME J. Energy Res. Technol. 116 ... 

In-house process control. This comprises the achievement of optimum efficiency in relation to production and processing methods including the introduction, where feasible, of cleaner processes (alternative technology) or processing methods (substitute materials and/or reformulations, process modifications, and equipment redesign). 

Water conservation/reuse/recycle. In this, the aim is to achieve optimum efficiency in relation to water use, looking at the possible elimination of use, the regulation of use to only specific requirements, sequential use, or reuse and in-process recycling. 

GaAs, CuInS2, CuInSe2- Semiconductor electrodes have received increasing attention as a consequence of their potential application in photoelectrochemical energy conversion devices. In order to achieve optimum efficiency, the knowledge of the surface composition plays a crucial role. Surface modifications may occur during operation of the photo electrode, or may be the result of a chemical or electrochemical treatment process prior to operation. 

In this energy chain, coal is gasified to generate synthesis gas. The H2 CO ratio required for an optimum efficiency is adjusted via the CO shift reaction of a part of the carbon monoxide (CO) contained in the synthesis gas. The remaining synthesis gas is converted to liquid hydrocarbons via Fischer-Tropsch synthesis or via methanol synthesis with a downstream MtSynfuels (trademark by Lurgi) process (see beginning of Section 7.3.4). The liquid hydrocarbon yield amounts to about 0.40 MJ per MJ of hard coal, which is of the same order of magnitude as in the case of BTL ( 0.40 MJ/MJ) to calculate the thermal process efficiency, the electricity export must also be taken into account (see Table 7.12). 

Because enzymes are insoluble in organic solvent, mass-transfer limitations apply as with any heterogeneous catalyst. Water-soluble enzymes (which represent the majority of enzymes currently used in biocatalysis) have hydrophilic surfaces and so tend to form aggregates or stick to reaction vessel walls rather than form the fine dispersions that are required for optimum efficiency. This can be overcome by enzyme immobilization, as discussed in Section 1.5. 

For optimum efficiency, humidity levels, temperature, and pressure should be monitored and controlled during the adsorption. The adsorption process of VOCs removal is exothermic in the most cases, which should be considered as a significant design parameter, since there is a risk of fire in the removal of high loads of organic compounds that exhibit high heats of adsorption. 

---