Waste reduction valves

For Steam Header Subsystem Steam enters a header (/) via boiler steam, steam from PRV (pressure reduction valve), turbine extraction, process waste heat boiler steam, and recovered steam from a flash dmm. Process steam generation and use depend on feed rate and process conditions. Steam leaves a header to go to steam turbines, processes, PRV as well as steam losses due to leaks, and trap losses. For the balance closure, steam input to a header must be equal to the output ... 

As with the electrical load profile, it is also necessary to analyze the heat load over the daily and annual cycles. Ideally, the heat load will match the available heat from the electrical generator (however, this is rarely the case). There will be periods when supplementary output will be necessary which can be achieved by, say, supplementary firing the waste heat gases of a gas turbine, or heat output reduction is necessary by the introduction of bypass stacks. For a steam turbine installation bypass pressure-reducing valves will be necessary to supplement steam output, while a dump condenser may be needed at low-process steam demands. The nature of the electrical and heat load will obviously have significant influence in the development of the scheme and scope of equipment. 

This represents a significant flow rate. Assuming a 15-min emergency response period to stop the release, a total of26,000 kg of hazardous waste will be spilled. In addition to the material released by the flow, the liquid contained within the pipe between the valve and the rupture will also spill. An alternative system must be designed to limit the release. This could include a reduction in the emergency response period, replacement of the pipe by one with a smaller diameter, or modification of the piping system to include additional control valves to stop the flow. 

Figure 5.13 — Irreversible-reusable flow-through sensor for the kinetic multidetermination of phosphate and silicate based on integrated sorption of a reaction product, reaction (/ situ reduction) and photometric detection. (A) Microsensor block (1) and components (2). (B) Continuous-flow configuration coupled on-line to the sensor. P peristaltic pumps SV switching valve W waste. For details, see text. (Reproduced from [39] with permission of the American Chemical Society).

Fig. 5.6. (A) Flow-injection manifold for the wet digestion of shellfish slurry samples C carrier solution, P peristaltic pump, 1C injector commutator, W waste, r restrictor. (B) Dynamic manifold for the analysis of sludge slurries in an on-line digestion-reduction system by Fl-HG-AFS IV injection valve, AFS atomic fluorescence spectrometer, P peristaltic pump. (Reproduced with permission of the Royal Society of Chemistry.)...

Pilot-operated valves, and to a lesser extent spring-loaded valves offer opportunities for waste minimization. Advances in sealing technology and reductions in friction/stiction may continue to be made to reduce accumulation and blowdown. The potential advantages of fluidic design to this goal are as yet unclear. 

Fig.4.9 Schematic diagram of a dual column FI on-line preconcentration manifold for vapour generation AAS with parallel column loading and sequential elution, a, elution sequence for column CA b. loading sequence. V, 8-channel multifunctional valve (missing channels in figure are blocked) Vjj, 2-way valve for controlling column elution sequence. SA. SB, samples B, buffer, E, eluent R, reductant SP, gas-liquid seperator. A, quaitz tube atomizer. Ar, argon flow W, waste [26].

Fig. 6. Schematic set up of the SI-ASV flow system CS, carrier solution Rl, holding coil R2, reaction coil SV, selection valve R, reductant S, sample MC, mixer chamber D, detector W, waste. Components of the electrochemical cell a, reference electrode b, tubular gold electrode c, glassy carbon counter electrode d, connector, e, O-ring.

FIA systems are better for specific cases, while SIA systems are more modular. The adjustment of a SIA system to an experimental scenario can take some time, but once the system is optimized it can run autonomously. This advantage and the substantial reduction in the volume of reagents consumed and waste produced, as well as the ability to utilize several chemicals (which is limited only by the number of valves in the valve selector) make SIA an attracting platform for remote environmental sensing. 

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