Products quality

Product quality may require low holdup and low temperatures. Low-holdup-time requirements may eliminate application of some evaporator types. Product quality may also dictate special materials of construction. 

In many food products, the desired crystalline structure provides a characteristic texture to the product. The crystals influence the texture by disrupting the continuous phase in which they are embedded. Ice cream or frozen desserts are good examples of this, where the ice crystal structure provides a certain characteristic smoothness and mouthfeel desired in the product. In these products, many small crystals of uniform shape and size are desired. If the crystals are too large, they can be detected in the mouth and the product is regarded as coarse. Crystal shape may also be important in some cases, although the effect of different shapes on product texture has not been studied in any quantified manner. 

Probably the most important phenomenon for controlling the crystal size distribution is nucleation. By controlling nucleation, the desired crystalline structure can be attained. In many food products, the nucleation rate curve increases initially as driving force increases, passes through a maximum and then decreases as viscosity limitations inhibit the rate of nuclei formation. An example of this nucleation behavior was observed for citric acid by Mullin and Led (1969). At very low temperatures, fewer crystals were formed and this correlated with the strong increase in viscosity at these conditions. This behavior has been described (Mullin 1993 Walton 1969 Van Hook and Bruno 1949) by  

If nucleation occurs at or near the peak of the nucleation rate curve, then the maximum number of crystals will be formed. To obtain many small crystals in a product, nucleation must occur at process conditions (temperature and concentrations) that correlate with this maximum rate. If nucleation takes place at some condition off the peak in the nucleation rate curve 0-e., temperature too high or too low), fewer crystals are formed, and these can grow to a 

Another important condition for producing many small crystals of uniform size is that nudeation takes place at one time. That is, process conditions must be set such that the entire mass of product attains the desired temperature and concentration at the same time. If the duration of nudeation lasts for any extended period of time, then a wide range of crystal sizes will be produced. The crystals that nucleate first have the opportunity to grow to 

In general, the quality of a blend is composed of multiple components and is given by the following blending rule (Favennec et al., 2001)  

Constraints (3.6) and (3.7), respectively, expressthelower and upper bound on quality constraints for all products that blend either by mass q e or by volume q e Q,. 

The term technological quality embraces all attributes relevant to the processing of fresh pork, including general meat processing and specific processing, such as for catering. 

Food safety. From the perspective of technological quality, safety is the major issue, as control of safety during processing and distribution of meat products according to legislation calls for high safety demands. Additionally, safety refers to the shelf life of meat products. 

Water-holding capacity (WHC). WHC includes the ability of fresh pork to retain water and bind extra water. The higher the WHC, the more valuable the pork will be for use in highly processed products. Drip loss is an ongoing 

Lipid characteristics. If the lipid becomes too unsaturated, the meat is not suitable for, for example, sausage production. Furthermore, products become oxidative unstable, accelerating rancidity problems, especially in many preheated catering products with an increased incidence of the development in warmed-over-flavour. Therefore, the anti-oxidative status of pork, for example content of vitamin, is an important technological quality criterion. 

The image of fresh pork is to a high degree determined by its sensory quality (palatability, tenderness, juiciness) and its appearance (especially colour, visible fat content and WHC) at purchase in the shop (Schifferstein and Ophius, 1988 Becker et al., 2000). 

The production of material of a consistent quality is one of the major goals of development work. Quality problems in a product are identified by the constant monitoring and analysis of the output from the plant, using statistical process control techniques [D-4]. Some of these methods have already been mentioned in Section B, 3.4.2. The avoidance of product quality problems results in direct cost benefits and also brings about a reduction in the environmental impact of its manufacture. This is because material does not need to be reworked, recycled or sent for disposal. A reduction in the number of inferior quality batches of material leads to an increase in output from the plant. More material is produced for the same effort, with the added benefit that it can be consistently supplied to the sales warehouse or be used in consuming processes. 

The resolution of problems associated with the production of inferior quality products are of such importance that they must take priority over all other, non-emergency projects. Once a quality problem arises it must be dealt with at the earliest opportunity otherwise sales and customer confidence will be jeopardised. This is a special kind of development work, which is often described as manufacturing support. On major manufacturing plants, a local plant development team, devoted to resolving quality and production problems on that plant will carry out this support work. In smaller companies, other R D projects will need to be delayed whilst effort is redirected to resolve an urgent quality problem. 

The scope has specified the quality of the product. To obtain this quality certain items must be accurately controlled. The process engineer must look at the process and determine what steps control what qualities. 

In the production of polyvinyl chloride by the emulsion process, the percentages of catalyst, wetting agent, initiator, and solvent all affect the properties of the resultant polymer. They must be carefully metered into the reaction vessel. The vinyl chloride used must also be very pure. Either the scope must specify that the purchased raw material shall meet certain specifications, or some purification equipment must be installed so that the required quality can be obtained. 

For many reactions the temperature and pressure determine the mix of the products. Under these circumstances it is very necessary to control these variables accurately. 

The stream leaving a reactor not only contains the product but may also include a series of by-products, unreacted raw material, solvents and various catalysts, surfactants, initiators, and so on. The unwanted material is removed from the product in a series of separations. Since each separation step is intended to remove certain compounds, the composition of the leaving stream must be monitored and controlled if the product quality is to be maintained constant. In the production of ethylene, c3 compounds, c4 compounds, and Cs compounds are all removed separately and are sold as by-products. Each of these by-product streams must also meet certain specifications and therefore must also be monitored and controlled (see Table 4-1). 

Obviously the quality and size of particles depend on the flotation and purification methods. Crystallization is the dominant method in Germany because of the quality of the raw material. Recent crystallization technology allows production of rounded grains of about 1-mm size, which is suitable for compaction. 

Most potash is sold without detailed quality specifications as to either purity or particle size. Potassium chloride is guaranteed to have at least 60% K2O (and potassium sulfate 50% K2O), but this is only a 95% 96% purity. The impurity is primarily assumed to be NaCI, but there are no specifications for it. With the technical (industrial) grades, however, the specifications for various uses can be very demanding for example, limits on heavy metals in KCl that is sold to KOH producers, KCl in bw-sodium food use, etc. 

Area betiwaen rarraw lines in giaph showrs the range of typical particle sizes of mslor U.S. concentrated phosphates 

There are two types of feeders gravity and force-type feeders. 

The force feeders are equipped with single or multiple screws. These screws may be positioned vertically, at an angle, or horizontally. Tapered screws deaerate and 

The caustic soda solution has a concentration of up to 32 1 wt% NaOH. If a NaOH concentration of 50 wt% is required, evaporation can be used. The typical NaCl content is 20 ppm in a 32 wt% caustic solution. 

The hydrogen has almost synthesis quality with a concentration of about 99.9 vol % H2 (dry basis). The chlorine has an oxygen content of about 1.5 vol % (dry basis). Chlorine with an oxygen content below 0.6 vol % (dry basis) can be obtained by acidifying the brine with hydrochloric acid. 

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As a consequence, other than its use in the ndM method, the refractive index is very often used in process operations because it can indicate smaii differences in product quality that would be missed by other measurements. The only restriction is that the color of the sample should be less than 5 on the ASTM D 1500 scale. 

The variation in concentration of different chemical families readily illustrates the benefit to a refiner that such an analysis can provide as much for product quality as for the chemical reactions taking place in the process. 

In France there are four categories of heavy fuels whose specifications are given in Table 5.19 the different product qualities are distinguished essentially by the viscosity, equal to or less than 110 mm /s at SOT for No. 1 fuel oil, equal to or greater than 110 mm /s for No. 2 fuel oil, and by the sulfur content varying from 4 wt. % (No. 2 fuel oil) to 1 wt. % (No. 2 TBTS - very low sulfur content fuel oil). 

The trend in d and has also been accompanied by improvements in product quality illustratisd by the increases in gasoline octane numbers and diesel oil cetane numbers. 

Furthermore, deeper hydrotreating is increasingly necessary to reduce SO emissions and to improve product quality ... 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

Maintenance and operating costs represent the major expenditure late in field life. These costs will be closely related to the number of staff required to run a facility and the amount of hardware they operate to keep production going. The specifications for product quality and plant up-time can also have a significant impact on running costs. 

The non-hydrocarbon components of crude oil may be small in volume percent, typically less than 1 %, but their influence on the product quality and the processing requirements can be considerable. It is therefore important to identify the presence of these components as early as possible, and certainly before the field development planning stage, to enable the appropriate choice of processing facilities and materials of construction to be made. 

Measured in MJ/m or Btu/ft, the Wobbe Index has an advantage over the calorific value of a gas (the heating value per unit volume or weight), which varies with the density of the gas. The Wobbe Index Is commonly specified in gas contracts as a guarantee of product quality. A customer usually requires a product whose Wobbe Index lies within a narrow range, since a burner will need adjustment to a different fuel air ratio if the fuel quality varies significantly. A sudden increase in heating value of the feed can cause a flame-out. 

When a customer agrees to purchase gas, product quality is specified in terms of the calorific value of the gas, measured by the Wobbe index (calorific value divided by density), the hydrocarbon dew point and the water dew point, and the fraction of other gases such as Nj, COj, HjS. The Wobbe index specification ensures that the gas the customer receives has a predictable calorific value and hence predictable burning characteristics. If the gas becomes lean, less energy is released, and if the gas becomes too rich there is a risk that the gas burners flame out . Water and hydrocarbon dew points (the pressure and temperature at which liquids start to drop out of the gas) are specified to ensure that over the range of temperature and pressure at which the gas is handled by the customer, no liquids will drop out (these could cause possible corrosion and/or hydrate formation). 

The operations group will develop general operating and maintenance objectives for the facilities which will address product quality, costs, safety and environmental issues. At a more detailed level, the mode of operations and maintenance tor a particular project will be specified in the field development plan. Both specifications will be discussed in this section, which will focus on the input of the production operations and maintenance departments to a field development plan. The management of the field during the producing period is discussed in Section 14.0. 

Product quality specification Contractual agreements Capacity and availability Concurrent operations Monitoring and control Testing metering Standardisation Flaring and venting Waste disposal Utilities systems... 

One of the primary objectives of production operations is to deliver product at the required rate and quality. Therefore the product quality specification and any agreed contract terms will drive the activities of the production operations department, and will be a starting point for determining the preferred mode of operation. The specifications, such as delivery of stabilised crude with a BS W of less than 0.5%, and a salinity of 70 g/m, ... 

Product quality is not limited to oil and gas quality certain effluent streams will also have to meet a legal specification. For example, in disposal of oil in water, the legislation in many offshore areas demands less than 40 ppm (parts per million) of oil in water for disposal into the sea. In the UK, oil production platforms are allowed to flare gas up to a legal limit. 

BE- Intelligent equipment process monitoring for consistent finished product quality fIMPROQ) D. Farrington Bribsh Steel PLC... 

The combined result of two such determinations yielded a leak size figure of 8.8% of the feed flow (with a relative standard deviation of less than 5%). This figure could sufficiently explain the product quality problems experienced, whose alternative explanation in turn was catalyst poisoning. 

Specifications, Standards, Quality Control, and Health and Safety Factors. The hardboard industry is represented by the American Hardboard Association (AHA). Specifications and standards are contained in several ANSI standards (8—11). These standards define the various hardboard product categories as well as specific product qualities required for each group. 

LPC Product Quality. Table 10 gives approximate analyses of several LPC products. Amino acid analyses of LPC products have been pubhshed including those from alfalfa, wheat leaf, barley, and lupin (101) soybean, sugar beet, and tobacco (102) Pro-Xan LPC products (100,103) and for a variety of other crop plants (104,105). The composition of LPCs varies widely depending on the raw materials and processes used. Amino acid profiles are generally satisfactory except for low sulfur amino acid contents, ie, cystine and methionine. 

Product Quality and Specifications. Most of the elemental phosphoms produced is converted to derivatives by the manufacturer. Some white phosphoms is sold on the open market. Typical manufacturers phosphoms analyses for a straw yellow product foUow ... 

The most common parameters used to measure product quality are moisture, color, granulation, sediment, and ash. 

Product Quality. Under ideal plant operating conditions, the quahty of products derived from continuous SO film sulfonator units is unlikely to be significantly different (1). Typical LAB sulfonic acid composition is ca 96.6% active sulfonic acid, 1.2% free oil, 1.2% H2SO4, and 1.0% water, the last added for stabilization purposes to break sulfonic acid anhydrides and pyro-acids (279). Klett color for a 5% active solution is typically 15—25. 

In some liquid-phase processes, catalyst components are slowly leached from the catalyst bed and eventually the catalyst must be replaced. The feasibility of this type of process involves economics, ie, the costs of catalyst maintenance and keeping a unit out of service for catalyst replacement, and product quality and safety, ie, the effects of having catalyst components in the product and their ease of removal. 

Statistical quality control is used to first measure and then continuously improve product quality. For example, The Dow Chemical Company s average 1989 performance compared to the typical sales specification were purity, = 99.65 wt % color, APHA = 4 acid (as HCl) = 7.3 ppm and water = 26 ppm. Averages of properties were based on rail car and tank tmck shipment samples during 1989. 

In recent years, production of liquid resins of higher purity, ie, higher monomer content and fewer side-reactions, has been accompHshed. This is in response to more stringent product quality requirements. 

In continuous processes where automatic feedback control has been implemented, the feedback mechanism theoretically ensures that product quality is at or near the set point regardless of process disturbances. This, of course, requires that an appropriate manipulated variable has been identified for adjusting tne product quality. However, even under feedback control, there may be daily variations of product quahty because of disturbances or equipment or instrument malfunctions. These occurrences can be analyzed using the concepts of statistical quahty control. 

A cocurrent evaporator train with its controls is illustrated in Fig. 8-54. The control system applies equally well to countercurrent or mixed-feed evaporators, the princip difference being the tuning of the dynamic compensator/(t), which must be done in the field to minimize the short-term effects of changes in feed flow on product quality. Solid concentration in the product is usually measured as density feedback trim is applied by the AC adjusting slope m of the density function, which is the only term related to x. This recahbrates the system whenever x must move to a new set point. 

Payroh overhead includes the cost of pensions, holidays, sick pay, etc., and is normally between 15 and 20 percent of the operating-l or cost. Laboratoiy work is required for product quality control, and its cost is approximately 10 to 20 percent of the operating-labor cost. 

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