Production operating windows

Some pump manufacturers use a different taetie to expand the operating window of their products. This is why the dual ohite pump exists. The dual volute pump is designed to operate over a wide range of flows and heads. 

In light of the many types of behavior plastics that can manifest and the considerable effect this behavior can have on the performance of the finished product, it behooves designers to become familiar with specific behavior characteristics of each plastic considered for an application. Recognize potential problems. A major cause for problems is not of poor product design but instead that the processes operated outside of their required operating window. This subject will be reviewed latter in this Chapter under PROCESS CONTROL... 

Production of hypochlorite takes place in a two-step absorption unit in which 23% caustic solution is fed counter-currently to the chlorine feed-stream. In the first step -the liquid jet-loop reactor - about 90% of the chlorine is converted to hypochlorite. In step two - a packed column - a very efficient absorption [1-3] is carried out in which the chlorine concentration in the off-gas is reduced to <1 ppm. The operating window of this apparatus with respect to chlorine load is quite large and varies from 100 to 6000 kg h-1 of chlorine. This high capacity is necessary for the consumption of peak loads from the electrolysis plant during short time periods. During start-up or shutdown of one electrolyser the total chlorine peak load can vary from 100 to 300 kg in just a few minutes. 

The production operating ranges/windows established from the heat penetration runs must assure all products in the test mns will meet the calculated requirement for the corresponding specification. 

These simple product operators precess in the x -y plane of the rotating frame at a frequency corresponding to the chemical shift in hertz relative to the center of the spectral window (the resonance offset Av = v0 — vr). The chemical shift frequency Av can also be represented as the angular velocity 2 in units of rad/s ( 2 = 2ttAv). Using 2 allows us to skip all the 2tt terms. 

Figure A.7 shows the time evolution of product operators as a result of chemical shift only. Each wheel represents one full cycle of evolution (rotation in the /-/ plane), starting on the right side and moving to the top (90° or tt/2 rotation counterclockwise), to the left side, and to the bottom. The center of the wheel is the rotation angle in radians is the I-spin offset (distance from the center of the spectral window in radians s-1) and is the S-spin offset. I-spin SQC rotates at a rate 2i S-spin SQC rotates at rate 2s DQC...

Regardless of the type of controls available, the processor setting up a machine uses a systematic approach based on experience or that should be outlined in the machine and/or control manual. It is a defined area or volume in a processing system s PC pattern. Within this window fabricated products meet performance/cost requirements. Note that a major cause for problems with any process can be that the process operates outside of their required operating window. 

As a second example, latex, used to produce latex gloves, is a natural ingredient produced from tree sap, which varies in consistency with weather conditions and geographic location. Each batch of latex must be analyzed to determine its properties and then adjusted to get a more consistent performance. This is an example of a feed-forward control mechanism. One cannot set an operating window on the amount of solids added because it depends on the batch of latex. One cannot set an operating window on the percent solids in the latex initially because nature cannot be controlled. However, a control mechanism can still be established that ensures that the product will consistently meet requirements. Again adjustment mechanisms are required. 

Problem definition. Firstly the key components are identified. These are products, sub-products and intermediates, as well as impurities with significant effect on product quality and operation. Then the impurities are traced by means of tables containing sources, sinks, exit streams, transit units and process streams. Formation and depletion of impurities must be supported by a consistent stoichiometry. Then an operating window is defined in terms of production rate, operation parameters and technological constraints. In principle, this step may identify a number of flowsheet alternatives, but supplementary alternatives may arise during the application of the procedure. 

A further opportunity for process optimisation involves the judicious selection of reaction conditions (temperature, pressure and hydrogen / hydrocarbon ratio) so as to promote the transfer of primary middle-distillate product into the vapour phase with a view to reducing its residence time in the catalyst bed and, consequently, preventing distillate loss via secondary cracking. This approach to improved overall distillate selectivity has previously been referred to by Filers et al. [2] and provides the incentive to optimise catalyst performance within the constraints of the operating window so defined. 

About 50% of AERT s production is sold into the window and door industry. The material is called MoistureShield and is similar to Choice Dek in composition. Crane Plastics also markets its TimberTech product to window and door manufacturers. Profiles made by modified technology of Strandex Corporation with high wood content (typically 70%) composite to tolerances of +0.001 in. can go directly to vinyl cladding operations, and can be used with other precision components such as extruded aluminum profiles. The Strandex product can also be stained or painted. 

Fluidized beds give relatively higher performance, but within a narrow operating window. Another type of reactors, the slurry reactor, effectively utilizes the catalyst because of their small particle size in the micrometer range. However, catalyst separation is difficult and a filtration step is required to separate fine particles from the product. Moreover, when applied in the continuous mode, backmixing lowers the conversion and usually the selectivity [2]. Conventional continuous tubular reactors are used as falling film or wall reactor with catalyst coated on the wall however, supply/removal of heat and often broad residence time distribution because of large reactor diameters are two main drawbacks commonly encountered with such reactors. 

Formulation, in which sustainability issues are considered and the basis of design i.e. product and feedstock purities ranges, production capacity, operating window and economics life-span accounting for sustainability aspects) are defined. 

The viability of the process is based on the low solubility of calcium sulfate phases in aqueous solutions. Upon controlled mixing of the solutions calcium sulfate crystals are produced and hydrochloric acid is regenerated [8]. Research on the determination of process operating windows such as temperature and concentration levels for the production of high quality calcium sulfate dihydrate (DH) or the valuable calcium sulfate a-hemihydrate (HH) phase instead of formation of low value anhydrite (AH) [9,10] has been undertaken. 

---