Tail-end system

In providing for SO2 removal, the tail-end system design adapts to a variety of situations by (1) providing flexibility in the selection of the most suitable additives (2) supplementing existing electrostatic precipitators on older units. 

Results from operation of laboratory prototype units show that both particulate matter and SO2 emissions can be reduced to acceptable levels. However, long-term operation on commercial-sized units must be demonstrated. Three types of C-E tail-end systems, as given below, are being installed by utilities on coal-fired units. 

Furnace injection systems are similar to the tail-end design except the limestone additive is injected into the furnace and removed in the scrubber. Two of these units, one of 125 MW and another of 430 MW, are installed at the Lawrence Station of Kansas Power and Light Co. Two more units of this design, each of 100 MW, are installed at the Hawthorn Station of Kansas City Power and Light Co. although one is currently being operated as a tail-end system on low sulfur Wyoming coal. 

Where necessary, particularly in naphtha steam crackers, the same type of tail-end system was used to hydrogenate methyl acetylene and propadiene in the feed to the C3 splitter. 

Feedback - Feedback describes the removal of a portion of the fluid from the tail end or the middle of a system, moving it back toward the inflow. Feedback is often used in reactors that utilize bacterially mediated reactions to ensure a bacterial population. For example, activated sludge systems that are oriented in a channel-type of arrangement often need feedback to perform properly. 

Satriana (2) provides a summary of the development of flue gas treatment technology. The first commercial application of flue gas scrubbing for sulfur dioxide control was at the Battersea-A Power Station [228 MW(e)] in London, England, in 1933. The process used a packed spray tower with a tail-end alkaline wash to remove 90 percent of the sulfur dioxide and particulates. Alkaline water from the Thames River provided most of the alkali for absorption. The scrubber effluent was discharged back into the Thames River after oxidation and settling. A similar process was also operated at the Battersea-B Power Station [245 MW(e)] beginning in 1949. The Battersea-B system operated successfully until 1969, when desulfurization efforts were suspended due to adverse effects on Thames River water quality. The Battersea-A system continued until 1975, when the station was closed. 

The copolymerization with alkyllithium to produce uniformly random copolymers is more complex for the solution process than for emulsion because of the tendency for the styrene to form blocks. Because of the extremely high rate of reaction of the styryl-lithium anion with butadiene, the polymerization very heavily favors the incorporation of butadiene units as long as reasonable concentrations of butadiene are present. This observation initially was somewhat confusing because the homopolymerization rate of styrene is seven times that for butadiene. However, the cross-propagation rate is orders of magnitude faster than either, and it therefore dominates the system. For a 30 mole percent styrene charge the initial polymer will be almost pure butadiene until most of the butadiene is polymerized. Typically two-thirds of the styrene charged will be found as a block of polystyrene at the tail end of the polymer chain ... 

While inorganic membrane reactors perform more efficiemly than conventional reactors in most cases, there are situations calling for the combined usage of these two types of reactors for reasons to be discussed. The conventional reactors in these special cases serve as either the pre-processing or post-processing step for the inorganic membrane reactor system to derive a maximum overall reaction conversion. These hybrid types of reactors consist of conventional reactors at the front end or tail end or both of the membrane reactor. 

Also using IRRAS, Mendelsohn and co-workers have studied monolayers of phospholipids with deuterated acryl chains. In such systems C-H and C-D stretching vibrations can be monitored simultaneously. This permits, for example, observation of individual components in a mixed lipid monolayer or conformational analysis of different parts of the acryl chains. Measurements on mono-layers consisting of tail-end deuterated DPPC molecules showed that the chains posses more conformational order adjacent to the head group than at their tails. ... 

Two types of systems, tail-end and furnace injection, have been installed by C-E. Figure 5 is a schematic flow diagram of the tail-end APCS. During operation, a slurry of pulverized limestone or a slaked... 

Process design the report gives several examples of products that reduce environmental impact. It also identifies that electricity is the principal component of the air separation process, and that we constantly strive to improve the energy efficiency of our plants . Even so a no score has been awarded since only one example of a process improvement is given (changing a cleaning system to reduce ozone emissions), while at the same time the report includes a number of examples where tail-end treatment has been used to reduce emissions. 

When optimized polysoaps bearing the analogous surfactant structure were used, only gradual differences in solubilization capacity were found. More polar solubilizates which are assumed to reside close to the micellar surface are somewhat more efficiently solubilized by polysoaps of tail end geometry. In contrast, solubilisates of amphiphilic structure are somewhat more efficiently solubilized by polysoaps of mid tail geometry. Polysoaps of head geometry fall shorter in both cases [78, 343], Similar comparative studies for pure aromatic compounds and hydrocarbons are not available. The differences observed may be due to the respective positions of the polymer backbones, occupying space which is needed to accomodate the solubilizate. Notably, the results imply that the optimal polysoap structure does not exist, but the systems of choise will depend on the problem adressed. 

Similarly, the ethylene-based control system was used to actively control the spark timing of the NFS predetonator tube. When ethylene is detected at the tail-end, a signal is sent to actuate the ignitor ensuring full tube fills and minimizing wasted fuel. As shown in Fig. 10.9, the missing peaks in the equivalence ratio histories are due to detonation failure due to pulse-to-pulse interference. The actively controlled spark is able to reduce this performance-degrading behavior. 

Adsorption by van der Waals interaction is important, not only as an independent mechanism, but also as a supplementary mechanism in all other types of adsorption (Rosen 1989). It accounts, in part, for the pronounced ability of long-chain ionic surfactant molecules to displace similarly charged simple inorganic ions from solid substrates. A number of crystalline systems are affected by the action of surfactants, often by van der Waals adsorption of the hydrocarbon portion ( tail-end ) of surfactants onto the crystal surface. 

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