This course of 15 lectures provides an introduction to open channel hydraulics, the generic name for the study of flows in rivers, canals, and sewers, where the distinguishing characteristic is that the surface is unconfined. This means that the location of the surface is also part of the problem, and allows for the existence of waves-generally making things more interesting! At the conclusion of this subject students will understand the nature of flows and waves in open channels and be capable of solving a wide range of commonly encountered problems.
The injection of exhaust-heat-generated steam into gas turbines for power augmentation has been proven to provide exceptional flexibility of operation in cogeneration applications. The chronology of development of this technology is presented, including a list of available turbines. A description is then given of the design process for converting existing gas turbines to steam injection. Finally, the water purification issue, which is perceived by some as a barrier to cost-effective implementation of such installations, is addressed. It is shown that water purification cost is of the order of 5 percent of the fuel cost and is therefore not a decisive factor.
From order-of-magnitude calculations, the erosion mechanism in slurry pumps for mining applications was found to be a scouring type. Impact erosion was found to be unlikely to occur. The erosion model assumes a “sliding bed” type of flow pattern and neglects the effect of turbulent diffusion of slurry particles. This choice was based on flow regime data from slurry pipeline flow and was not verified experimentally in pumps. A new centrifugal-erosion laboratory testing fixture was designed and fabricated at Allis-Chalmers which reproduces this type of erosion. Since flow conditions were closely controlled, an absolute rate of erosion could be determined. For mild steel (Rockwell C = 10) and aluminum oxide particles, a specific erosion energy of 1.5 × 108 in-lb/in3 (1000 joules/mm3) was measured. Flow pattern and slurry concentrations were calculated in a pump impeller using a quasi-three-dimensional streamline curvature method. These were combined with the above erosion model and the local erosion rate was estimated. Actual operating data had to be estimated for a quarry application of the pump because field test data was not available. The uncertainties of the field test data did not allow an exact numerical verification of the wear rate calculation, but order of magnitude agreement was obtained. The wear rate distribution agreed very well with the wear pattern observed on the impeller used in the quarry and the locations of excessive wear could be identified.
The Potential for reducing emissions from gas turbines by injecting steam for Nox control and hydrogen for Co control is evaluated through laboratory-scale combustion experiments. Results showed that hydrogen addition into a steam-injected diffusion combustor at hydrogen/fuel molar ratios of approximately 20 percent was associated with somewhat increased NOx production and reduced CO emissions. Both effects are attributed to an increase in the local stoichiometric flame temperature. However, the decrease in CO was greater than the increase in NOx, resulting in a net emissions benefit, or a shifting of the NOx–CO curve toward the origin. Consequently, a greater range of NOx/CO emissions targets could be achieved when hydrogen was available. Additional experiments on premixed systems with hydrogen injection showed a significant increase in operability. Cost estimates for producing hydrogen with a conventional fired steam reformer suggested high capital costs unless ample steam, is already available. Hence, the technology is particularly well suited for turbines that use steam for power augmentation. Alternate reforming technology, such as catalytic partial oxidation, offers the potential for reduced capital costs.
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