Upstream operations

In a chemical production process at least one of the unit operations (the chemical reactor) is the place in which chemical conversion takes place. However, the chemical upstream reactor is proceeded by a series of unit operations in which the new materials are downstream prepared (the upstream operations). After conversion has taken place, the products are operations subjected to a further series of unit operations (the downstream operations). These downstream operations include product recovery and purification steps. A typical example of a production process is illustrated in Figure 1.1. 

Such infrequent measurements make the control of the product quality difficult. At best, the operators have learned a set of heuristics that, if adhered to, usually produces a good product. However, unforeseen disturbances and undetected equipment degradations not accounted for by the heuristics still occur and affect the product. In addition, there are periods of operation when the final process step produces a degraded product in spite of near-perfect upstream operations. 

Another vital part of such projects is contaminant removal. Notwithstanding the hydrogenation of the DCC VGO feedstock, the light hydrocarbon products from such units will contain a range of contaminants at various concentrations depending upon upstream operating conditions ... 

The dispatching procedure regulates information flow between stakeholders such as the production field operators, upstream operators and upstream shippers, Gassco, and downstream operators. The dispatching includes information on available production capacities, forecasts, nominations, instructions, reporting and much more. 

Although this discussion provides insight to the types of solubility behavior that can be exhibited by various systems, it is by no means a complete survey of the topic. Extensive solubility data and descriptions of more complex equilibrium behavior can be found in the literature. Published data usually consist of the influence of temperature on the solubility of a pure solute in a pure solvent seldom are effects of other solutes, co-solvents, or pH considered. As a consequence, solubility data on a system of interest should be measured experimentally, and the solutions used in the experiments should be as similar as possible to those expected in the process. Even if a crystallizer has been designed and the process is operational, obtaining solubility data using mother liquor drawn from the crystallizer or a product stream would be wise. Moreover, the solubility should be checked periodically to see if it has changed due to changes in the upstream operations or raw materials. 

All of the acid dilution rates are large and the resulting fresh acid costs are adequate to support efficient feed fractionation and treating facilities, frequent maintenance and close operator observation and control of upstream operations. Assuming this is done, the major remaining concern Is the operation of the alkylation unit proper, particularly the reactor section. 

The selection of dryers for polymer drying depends to a large extent on the upstream operations, e.g., polymerization, since the behavior of a polymerization reaction and the properties of the resulting polymer can vary greatly according to the nature of the physical system in which the polymerization reaction is carried out. Several processes are used commercially to prepare polymers. Each process has its advantages, usually depending on the type and final use of the polymer. 

PP is produced by a variety of processes, most of them by a diluent phase propylene polymerization utihzing a Ziegler-Natta-activated titanium trichloride catalyst in the presence of low- to high-boiling hydrocarbons. Residual catalyst removal followed by hydrocarbon slurry centrifugation is the immediate upstream operation prior to thermal drying. Hexane is the solvent used in the major PP processes in operation today. As a result these polymers are solvent wet. 

Material carry over and impact on downstream and upstream operations fouling, foaming, corrosion, cyding, leaks, recycle, and stable emulsion formation. 

This system creates links between operations, notifying upstream operations when to move and make production nits. 

Kanban systems to pull product through the factory and supply chain. These systems create links between operations, notifying upstream operations when to move and make production units. The tool supports the demand-driven supply chain. 

Managing consumption begins by defining the Time between Purchases, or TBP. These purchases do not have to be from outside vendors. They include pulls from upstream operations such as packaging or fabrication inside the company. 

In many cases, surfactant is applied to the fiber for rewetting, lubricity, antistatic, or other purposes, while in other cases the surfactant affects the processing solution in some way, such as stabilization of an emulsion or dispersion. Surfactant residues are present in fiber, yam, or fabric from applications in upstream operations. Oils and waxes on natmal fibers, fiber finishes on synthetic fibers, winding emulsion on yam, coning oil, yam finish, knitting oil, and warp size are examples of surfactant-containing residues found on textile substrates [10]. In addition to uses in which the surfactant is applied to the substrate, many textile processes use water-insoluble textile processing assistants that are applied from aqueous emulsions. Essentially all chemical specialties contain surfactants to improve solubility and dispersability and to suspend water-insoluble materials... 

Operators at the downstream receiving unit often blame all of their problems on poor feed. The upstream operators are labeled as careless the downstream operators are complainers. The operating engineer is the one in the middle who has to solve the puzzle. 

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