Streaming processors

Ammonium thiosulfate, stable as a solution, is produced ia the form of a 56—60% solution from ammonia and soHd sulfur or an H2S-rich gas stream or both soHd sulfur and H2S gas streams (68). As a result of avadabihty, only development of solutions for processing x-ray and color film and prints has been encouraged. The evolution of automatic processors to develop and print color reinforced the trend toward use of solutions. Most x-ray laboratories and automatic film and print processors require almost immediate results. 

The family of short curves in Fig. 29-45 shows the power efficiency of conventional refrigeration systems. The curves for the latter are taken from the Engineering Data Book, Gas Processors Suppliers Association, Tulsa, Oklahoma. The data refer to the evaporator temperature as the point at which refrigeration is removed. If the refrigeration is used to cool a stream over a temperature interval, the efficiency is obviously somewhat less. The short curves in Fig. 29-45 are for several refrigeration-temperature intervals. A comparison of these curves with the expander curve shows that the refrigeration power requirement by expansion compares favorably with mechanical refrigeration below 360° R (—100° F). The expander efficiency is favored by lower temperature at which heat is to be removed. 

Gary Jacobs and Burt Davis (University of Kentucky) review catalysts used for low-temperature water gas shift, one of the key steps in fuel processors designed to convert liquid fuels into hydrogen-rich gas streams for fuel cells. These catalysts must closely approach the favorable equilibrium associated with low temperatures, but be active enough to minimize reactor volume. The authors discuss both heterogeneous and homogeneous catalysts for this reaction, with the latter including bases and metal carbonyls. 

The GPCR system is used to treat solid and gaseous streams. Organic compounds are thermally desorbed from the solids, which are 5X treated in the associated thermal reduction batch processors (TRBPs). The GPCR reactor treats the desorbed gas-phase organic compounds via chemical reduction with hydrogen. 

The additional issue for PEM is the minimization of steam needed for the fuel processor system. Since an APU is a mobile and/or remote unit, the need for external sources of water should be minimized. The reformate stream is further diluted by additional steam, if that water is not removed prior to the fuel cell stack. 

The TC biodiesel fuel processor instead consists of a two-reactor system, in which one reactor, the cracker, is used for production, while the other one is being regenerated by gasification of the deposited sohd C with steam yielding H, COj, CO and CH (Ledjefif-Hey et al., 2000). The product gas streams of the TC and the gasification unit are combined, cooled down to the shift inlet temperature and then fed to the shift reactor and the CO-purification step. First, the cracking of biodiesel takes place for the production of H ... 

As mentioned earlier, reformate from a fuel processor often needs addition processing to reduce the carbon monoxide levels. Researchers at the Stevens Institute of Technology are developing a microscale preferential oxidation (FrOx) reactor to decrease the carbon monoxide level in the reformate stream to below 100 ppm. As part of their research, they used advanced computational fluid dynamic modeling. 

Recent fuel processor performance is summarized in Table 4. The fuel processors were operated at atmospheric pressure, and the water and methanol feed mixture was about 60 wt % methanol. The typical composition of the reformate stream was 72— 74% hydrogen, 24—26% carbon dioxide, and 0.5—1.5% carbon monoxide on a dry gas basis. The carbon monoxide levels were significantly below equilibrium (5.4% at 350 °C), but they still require additional cleanup for use in fuel cells. The fuel processor efficiency was calculated using eq 5 and was reported to be greater than 80%. It is interesting to note that increasing the power 5-fold, from 20 to 100 W, only resulted in a 50% increase in volume and a 33% increase in mass. 

Techniques for purification of acid gas streams by removal of H2S, COS and carbon dioxide are standard technology. Recovery of elemental sulfur from these acid gas streams by use of Claus or Stretford units is also conventional technology. These technologies are being practiced on a large scale by both petroleum refiners and natural gas processors. 

Trend outputs consist of a continuous electrical signal [0 to 10 volts or 4 to 20 mini (inA)] from Ihe processor. As many as 30 to 40 such outputs may be available from a single processor. Each output represents Ihe concentration of a particular component in one of the sample streams on a given analyzer sealed lo some convenient range. Component identity and scale factors for each output channel are user-assigned from the processor keyboard. 

Particle size reduction of a material suspended in a liquid medium can be affected by a Microi uidizeP processor (MicroLuidics Corp., Newton, MA, http //www.microLuidicscorp.com/ processors.html). A schematic of a MicroLuidizer processor is presented in Figure 17.6. In a Micro-Luidizer processor, a liquid stream is bifurcated and the two streams are directed upon each other under pressures as high as 40,000 psi. Particles suspended in the liquid are reduced in size by forces of shear and cavitation. Suspensions can be prepared with the MicroLuidizer processor with mean particle sizes in the micron to submicron range. 

The memory organization of DSPs are also different from ordinary processors because (1) Memory is typical static RAM and virtual memory support is totally absent (2) Several machines separate data and instruction streams (Harvard Architecture) (at the cost of extra pins). Additionally, modular arithmetic address modes have been added to most processors. This mode finds particular utility in filter coefficient pointers, ring buffer pointers and, with bit reversed addressing, FFTs. One further difference is the use of loop buffers for filtering. Although often called instruction caches by the chip manufacturers, they are typically very small (for example, the AT T DSP-16 has 16 instructions) and furthermore, the buffer is not directly interposed between memory and the processor. 

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