Minimizing Scale

Some chemical product manufacturers claim a need for higher dose rates (say, up to 10 ppm) to minimize scaling and fouling tendencies, but this is usually prohibitively expensive and may well prove to be an overdose. 

Sludge conditioners are required. Originally these were based on starches and lignins, but modem carbonate cycle treatments use carbonate-polymer programs, where the polymer (such as a phos-phinocarboxylic acid) provides a combination of threshold effect, crystal distortion, and sludge dispersion to minimize scaling and prevent sludge deposition. 

Capital Equipment Costs The initial investment made by a utility to control pollutant emissions is in the equipment comprising the flue gas treatment system. The amount of the investment in this equipment purchase is directly related to the size and complexity of the equipment itself. The vessels required in this application must be large because of the volume of flue gas that must be treated. Some equipment, such as spray dryers or absorbers, can be 20 to 50 feet in diameter, and spray towers can be over 100 feet in height. Considerable preparation must go into sizing these vessels properly in order to maximize gas-sorbent contact time and minimize scaling and other operational problems. Much of this equipment, especially in wet systems, must be constructed of costly corrosion-resistant materials. Elaborate valving systems must be set up to control flows to the system. 

The Claisen rearrangement, Cope rearrangement, and associated variants are powerful tools that can be used to create a number of new chiral centers in an expeditious manner, but the use of heavy metals, such as mercury, should be avoided. Of these reactions, the Ireland-Claisen ester enolate reaction provides the most versatile synthetic pathway with minimal scale up problems. 

It is well-known that in a poor solvent there exists some critical chain length, g, depending on temperature and energy of volume interactions, so that chains longer than g collapse. With regard to sufficiently long chains, we shall define these g -link parts as crumples of minimal scale. 

The system of densely packed globulized crumples corresponds to the chain with the fractal dimension df = 3(df = 3 is realized from the minimal scale, g, up to the full globule size). The value g is in the order of... 

Scaling of RO membranes is a result of precipitation of saturated salts onto the surface of the membrane. Table 3.5 lists generally-accepted water guidelines for minimizing scaling of RO membranes.3 The table includes the following species ... 

Projections indicate that about 3 ppm of antisealant is required to minimize scaling due to hardness. At a local cost of 4.50 per pound, the monthly cost for antisealant is 46. 

A, where the minimal scale X and the maximal scale A are determined by the measurement technique. 

Formulation and/or development of advanced drug-delivery systems such as microencapsulated molecules, transdermal patches, or liposomes are frequently accomplished in the laboratory. However, large-scale production of these dosage forms may be problematic because the same conditions of manufacture may not be attainable or desirable in the plant setting. Consultation with process development personnel during the finalization of the prototype development phase is one way of minimizing scale-up difficulties. 

The objective of minimizing scale formation was met because no significant build-up of sand or other materials could be detected in the combustor, external boiler, piping, and cyclones after shutdown and inspection. The problem of agglomeration and build-up was apparently minimized by the addition of clay. 

Minimizing Scale Formation in Saline Water Evaporators... 

Pilot Plant Testing (Scale-up Verification) The primary goal of pilot plant testing [Figure 9] is to minimize scale-up uncertainty. An SCFCO2 pilot plant is typically 50-200 liters in extraction capacity. Pilot plant tests are designed to verify ... 

The data on corrosion is voluminous. A few other particularly pertinent references are Lindqvist and Magnusson (17) indicate that there is an optimum NaOH to SiO ratio for minimizing scale formation while still retaining good corrosion protection for dairy cans and pipelines Wildbrett et al. (18) discuss corrosion of aluminum by alkaline sprays Savchenko... 

Membrane treatment plants have recently become more common, with a wide variety of membrane types and configurations being used (Fig. 3). Each membrane system will generally utilize pretreatment to remove large particles, to adjust pH, disinfect, and/or minimize scaling. 

Fig. 6.24. Three-zone reheat furnace temperature control for best productivity, least fuel rate. This control system minimizes scale formation by preventing overheating. Scale accumulation forces bottom zone gases to top zone, reducing bottom side heating. PV = process variable SP = setpoint T/s = temperature sensor.

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