Reducing capacity

Carboxylate exchangers contain —COOH groups which have weak acidic properties and will only function as cation exchangers when the pH is sufficiently high (pH > 6) to permit complete dissociation of the —COOH site. Outside this range the ion exchanger can be used only at the cost of reduced capacity. 

Poor performance can result from fan inlet eccentric or spinning dow, and discharge ductwork that does not permit development of hiU fan pressure. Sometimes inlet restrictions starve a fan and limit performance. To obtain rated performance, the air must enter the fan uniformly over the inlet area without rotation or unusual turbulence. This allows all portions of the fan wheel to do equal work. If more air is distributed to one side of the wheel, such as with an elbow on the inlet, the work performed by the lightiy loaded portions of the wheel is reduced and capacity is decreased by 5—10%. The use of an inlet box duct on a fan can reduce capacity by as much as 25% unless there are turning vanes in the duct. Use of the vanes reduces the capacity loss to around 5%. 

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. 

Vitamin Deficiency. Vitamin deficiency is uncommon in normal adults. However, when it does occur, it can be serious, particularly in pregnant women. Some vitamin deficiency can occur because of a large reduction of fat intake, which decreases absorption. Strict vegetarians also risk reduced vitamin intake. Premature infants and elderly people who are exposed to minimal sunlight and consume Htde vitamin also have a reduced capacity to metabolize and can develop vitamin deficiency. 

FIG. 11-98 Performance of complete refrigeration system (1), when there is reduction in heat load (2), and when for the same ambient (or inlet in evaporator) evaporation temperature is maintained constant hy reducing capacity of compressor/condenser part (3). 

Moisture may create poor discharge conditions because of material sticking to the belt and to chutes, or it may even reduce capacity if it is present in enough quantity to give the material fluid properties. Even though abrasion may create problems with belt conveyors, these are easier to solve with properly designed belt systems than with most other conveyors. 

Duration of operation at reduced capacity = say, for 25% of total working hours. 

Energy consumed while operating at the reduced capacity for 25% duration = 0.25 x 720 000... 

Support plate used as a vapor distributor with restricted open area. Reduced capacity in order to make separation. Design error. 

An oversized relief valve may also chatter since the valve may quickly relieve enough contained fluid to allow the vessel pressure to momentarily fall back to below set pressure only to rapidly increase again. Rapid cycling reduces capacity and is destructive to the valve seat in addition to subjecting all the moving parts in the valve to excessive wear. E.xcessive back pressure can also cause rapid cycling as discussed above. 

Although total usage of PAEK materials was estimated as being as high as 5000 t.p.a. in 1995 the withdrawal of all suppliers except Victrex reduced capacity to about 1600 t.p.a. by the end of 1996. In 1998 however Victrex announced a capacity expansion to 2000 t.p.a. 

Air cooled heat exchangers will continue to operate (but at reduced capacity) due to radiation and natural convection air circulation should a power failure occur. 

Pony motors are additional, small motors connected to the same fan shaft. They are typically about 1/4 the size of the full size motor. Pony motors do not lend themselves to gear box applications and are, therefore, primarily applied to belt drive applications. The big motor operates when full capacity is required and the small motor simply free wheels. At reduced capacity, the small motor operates and the big motor spins freely. 

Add variable clearance to reduce capacity initially at low temperature at high temperature clearance is removed to increase actual throughput. 

Reciprocating compressors are classified as constant-volume, variable-pressure machines. They are the most efficient type of compressor and can be used for partial-load, or reduced-capacity, applications. 

Temperature is of particular importance to the performance of anodes, especially when anodes are buried. Anodes may often be used to protect pipelines containing hot products. Thus temperature effects must be considered. Figure 10.14 illustrates the effect of temperature on different anodes in hot saline mud. Al-Zn-In anodes experience greatly reduced capacity in open seawater at temperatures above 70°C (down to 1200Ah/kg at 100°C) and in seabed muds in excess of (900 Ah/kg at 80°C). At... 

The capacity of an anode is dependent on the anode current density. To some extent it will be governed by the exposure environment but, in part, is within the control of the design. Certainly wholly unsuitable current densities can usually be avoided. At lower operating current densities some anodes exhibit reduced capacity this is shown in Fig. 10.17. Long periods of low operating current density can lead to passivation. This may result in failure to activate when the current demand increases (as can occur with anodes on coated structures when the coating deteriorates). 

Aluminium anodes are less constant in their electrochemical characteristics than zinc. This presents no major problem provided the designer is aware of their properties. They suffer from reduced capacity and increased operating potential (and hence risk of passivation) with increasing temperatures above approximately 50°C (Fig. 10.14), decreasing salinity (Figs. 10.15 and 10.16) and decreasing operating current density (Fig. 10.17). 

In marine sediments, usually only the uppermost layer of the sediment exhibits oxidizing conditions while the rest is reduced. The thickness of the oxidized layer and the reducing capacity of the sediment below depend on ... 

An interesting development is the combination of HPLC and on-line measurement of reducing capacity or antioxidative activity. This approach allows both direct identification of antioxidative species in complex foods and quantification of the contribution to the overall antioxidative capacity in the absence of synergistic and antagonistic effects. Major advantages are less sample handling and the ability to rim large series of samples in an automated process. 

The on-line measurement of reducing capacity can be performed with either a single or a series of electrochemical detectors, and linear correlations have been demonstrated between total antioxidative activities determined by the electrochemical detection and those determined by DPPH- reduction or by the ORAC assay (Guo et al, 1997 Peyrat-Maillard et al, 2000). The reducing capacity must also be quantified by post-column reactions, either with DPPH- or by the reduction of phosphomolybdenum complexes followed by UV-VIS-detection (Bandoniene and Murkovic, 2002 Cardenosa et al, 2002). A combination of HPLC and semi-automatic ORAC analysis has also been described (Caldwell, 2001). 

There is evidence from a number of in vitro studies that the vitamin E peroxyl radical formed during fatty-acid degradation may be converted to vitamin E plus nonradical through the actions of vitamin C (Burton et al., 1985). RA patients have reduced serum ascorbate levels (Situnayake et al., 1991) and potentially a reduced capacity for the regeneration of vitamin E. In vitro studies suggest that vitamin E becomes a pro-oxidant when ascorbate levels are low (Bowry and Stocker, 1993). 

In the first case the mechanisms are based on an increased reducing capacity of Fe(lll)-chelates, a necessary step in the uptake process, with a concurrent increase in acidification and release of organic acids into the rhizosphere in the latter case molecules having high affinity for Fe (phytosiderophores) are synthesized and released into the rhizosphere when Fe is lacking. 

The total investment cost was approx. 3 milj. Euro. The additional cost to solve initial problems (1998-1999) was approx. 1 milj. Euro. This means a specific investment cost of approx. 250 Euro/kW calculated with the reduced capacity of 15 MW. 

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