Maximum hydraulic capacity

Strigle [82] identifies a regime 20% above point F on Figure 9-22 as the maximum hydraulic capacity and is termed the flooding point for atmospheric operations. 

The recommended design procedure for an approximate evaluation utilizes a final design vapour-rate, Cs, which is a percentage of the reduced maximum operational capacity factor (usually between 80% and 87%). Note that in high-pressure operations, the usable hydraulic capacity of the tower packing may be reached because of excessive liquid hold-up before the... 

Tubular filters (Fig. 10) offer low cost construction and high hydraulic capacities. They are made with both rigid and flexible tubes. Celite is used on the rigid tube filters in the usual combination of precoat and body feed. With flexible tube filters, instead of body feed, an extra heavy precoat [25-30 lb (11.4-13.6 kg) filter aid per 100 ft (9.29 m ) filter area] is used. After filter pressure has reached a maximum, the precoat is bumped from the tubes, re-slurried, then re-deposited. This sequence is repeated until pressure is no longer reduced significantly, at which time the precoat is discarded and a new one applied. 

Above this gas rate, the column will approach the maximum hydraulic capacity, or flooding limit. The definition of flooding limit is not precise, but has varied with the observer. Some of the definitions of flooding limit which appear in the literature are as follows ... 

The use of maximum operational capacity produces a design that provides the desired efficiency, and the packed bed does not operate in an unstable region near its hydraulic capacity limit. 

The standard maximum Cs value (Co) from Figure 7-6 for 50 IMTP packing at this flow parameter is 0.266 ft/s. Adjustment for physical properties gives a maximum operational of 0.238 ft/s. Because the vapor density is 6.5% of the clear liquid density, the hydraulic capacity limit will be checked using Equation 1-5 (from Chapter 1). 

Flooding correlations for packed liquid extractors have been developed in a manner similar to those used for gas/liquid systems. Just like the air/water system used to evaluate the maximum hydraulic capacity for a gas absorption operation, the capacities in liquid-liquid systems are based on hydraulic flow rates for immiscible solvents in the absence of any mass transfer. As has been stated, the transfer of a solute can change the properties of the extract and raffinate phases in a significant manner. For this reason, it may be that flooding has been experienced in commercial operations at flow rates well below those predicted by the flooding correlation. Clearly, more research is needed to explain the effect of mass transfer on the capacity of a liquid extractor. Nevertheless, the application of a widely used flooding correlation will be reviewed. However, the designer should consider the limitations of this correlation and apply appropriate safety factors in the specification of equipment. 

Most investigations of the flooding rates in packed columns have been carried out using binary pairs of solvents without solute transfer. Thus, such correlations represent the maximum possible flow rates, because solute transfer usually affects the properties of the two phases so as to reduce hydraulic capacity. 

The column can operate actually up to the flooding point F. But it is easy to see, that die maximal efficient capacity (MEC or C ) is reached in point G. That is why the detenninadon of this point is very important. The rate in it provides perfectly stable operation because it has been determined from the sepmation efficiency. This appro h to packed column capacity has been verified the investigation of Kunesh et al. [49]. The maximum hydraulic capacity of the packing is about 20% higher than dus in point G [3, p. 145]. 

Flow through each control valve usually has three difierent capacities maximum, normal, and miniinuin. Hydraulic study is usually either based on maximum flow or normal How. From hydraulic study (without pump or compressor available pressure drop of the control valve at cither condition (case 0) is calculated. The available control valve pressure drop at other two flow conditions (case 1 or 2) can be estimated by following equation ... 

Fatigue tests were performed under load control mode on a Schenck horizontal fatigue testing machine with hydraulic grips and a maximum load capacity of 25 kN. Tension-tension constant amplitude fatigue tests were carried out at three stress levels 60% a , 70% Cu and 80% a at two different stress ratios R = 0.1 and R = 0.5. The test frequency was kept constant (f = 3 Hz) for all the tests. 

The theoretical maximum cooling capacity of a heat exchanger for a hydraulic system will never have to be greater than the input horsepower to the system. Usually its capacity can be considerably less, based on the calculated input horsepower. A mle of thumb is to provide a heat exchanger removal capacity of about 25 per cent of the input horsepower. Rarely, even on inefficient systems, would a capacity of more than 50 per cent be required. 

As seen from Fig. 14 the maximum reservoir pore-pressure at the apex of hydraulic compartments II and III lie in the order of 100 bar below the minimum fracture gradient. This pressure difference (i.e., effective horizontal stress or retention capacity, R ) decreases with depth and goes below 70 bar at approximately 3500 m. 

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