File Name: product and process design .zip
The presence of at least one chemical reactor and one or more separation sections for the separation of the effluent mixture leaving the reactor s characterizes many chemical processes. In almost all cases, one or more of the streams leaving the separation section s is are recycled to the reactor. In Chapter 6, the design of reactors and reactor networks was considered without regard for the separation section s and possible recycle there from.
An interpretative chart is proposed on several levels, which on the one hand acts as a key to the actions aimed at revision of simultaneous design criteria, and on the other is a methodological indication of how to articulate simultaneous actions on the product and the process. Finally, ways of carrying out simultaneous actions on the product and the process, together with the problems involved are discussed.
Critical design decisions are commonly made throughout the product development process assuming known material and process behavior. However, stochastic variation during manufacture can inadvertently result in inferior or unacceptable product performance and reduced production yields. Stochastic simulations have been developed to estimate the end-use performance distribution prior to the commitment of hard tooling. This article proposes a definition for integrated product and process robustness, and extends existing stochastic methods to model the important role of the manufacturing flexibility in elimination of defects and product optimization.
Reader comments, questions, and suggestions are needed to help us fulfill our objective for this column. Please send your comments and suggestions to column coordinator Yihong Qiu at qiu. Virtually all materials exhibit this property under appropriate conditions.
For example, tablets are made by mixing solid ingredients e. In pharmaceutical development, material properties of these solid ingredients, particularly mechanical properties, often play an important role in the fabrication of drug products. In certain cases, thermal properties may also become important e. By definition, mechanical properties are those of a material under an applied stress, including hardness, elasticity, plasticity, brittleness, the Poisson ratio, yielding stress and elongation, etc.
They are used as measurements of how materials behave under a load. Scientific understanding of these properties and their impact on product design, performance, and manufacturing is essential to the rational development and successful production of solid dosage forms.
Powder handling is an essential part in the development and manufacture of solid dosage forms. It is involved in virtually every stage of drug product manufacture such as conveying, blending, transfer, storage, feeding, and compaction. Two basic aspects of powder handling are powder flow and powder compaction, both of which depend on physicochemical and mechanical properties of the solid materials used.
Stress And StrainStress is a measure of the average amount of force exerted per unit area of a surface within a deformable body i. However, any arbitrary external force Coordinated by Yihong Qiu. Stress has the unit of pressure. Strain is a measure of the extent of deformation.
It is defined as the relative displacement in a material. Normal stress causes normal strain i. Shear strain may also be defined by the angular distortion caused by the shear stress i. Elastic Deformation And Modulus Of ElasticityIn the absence of external force, molecules are in their equilibrium positions with lowest free energy as determined by the inter-atomic and intermolecular forces.
In response to an applied stress, molecules or their parts will change their mutual positions from their original equilibrium positions to new positions with higher free energy. Thermodynamics then compels molecules to return to the original positions with the lowest free energy, resulting in a returning elastic force that counterbalances the applied stress.
At the new equilibrium position, the internal elastic force equals to the applied external force. Within a limited extent, the deformation of a solid body is reversible. This type of deformation is referred to as the elastic deformation. Elastic deformation obeys the Hook's Law, which states that the deformation is proportional to the applied stress. It is defined as proportionality coefficient between the tensile stress and the strain, as in equation 2:[Equation 2]Elongation along the tensile direction, x, is usually accompanied by contraction along the directions perpendicular to the tensile stress i.
Plastic DeformationPlastic deformation refers to irreversible changes in the internal molecular structure or microstructure of a material subject to applied stress. Plastic deformation is a result of viscous flow, as described as follows. The characteristic of a liquid is the non-fixed positions of its constituent molecules.
As a result, liquid has no particular shape. Therefore, the deformation of a liquid itself does not produce elastic force as in elastic solids because the microenvironment of each molecule stays as the same before and after deformation. However, the process of deformation is related to the shear stress. The higher the shear stress, the more rapid the deformation.
The relationship between shear stress and strain rate in viscous flow is related to the viscosity. It is also shown the strain rate is the same as the velocity gradient along the direction perpendicular to the shear stress. ViscoelasticityViscoelasticity is a combination of viscosity and elasticity. The majority of mechanical bodies exhibit both elastic and viscous behavior. The viscoelasticity of a material may be better characterized by a combination of elastic springs and viscous damping elements.
For example, the Maxwell's model consists of an elastic spring and a viscous dashpot in series, while the Kelvin or Voigt model consists of these two elements in parallel Figure 2. For example, the Maxwell and Kelvin models satisfy the following equations, respectively: Under dynamic conditions such as those encountered using a rotary tablet press, the strain may be represented as a sinusoidal wave, and the resulted stress will also vary sinusoidally, but with a phase lag.
Viscoelasticity of many materials are more complicated than what can be described by the simple Maxwell or Kelvin model. Improved representation may be achieved using various combinations of the two elements; however, it can rarely be reproduced perfectly. The situation with nonlinear viscoelasticity is even more complicated. Nevertheless, viscoelasticity makes the compaction behavior of a material more difficult to predict from one set of conditions to another.
For brittle materials, the fracture will occur when the stress exceeds the elastic limit. Non-brittle material initially exhibits the elastic deformation. When the applied stresses increase beyond the capability of the material to balance them by elastic forces, the material will yield, and the elastic region ends when material reaches its yield strength.
Subsequently, plastic deformation or plastic flow starts, which is irreversible. This region is clearly one of nonlinear viscoelasticity. Polymeric materials may extend at constant stress in this region that is often referred to as cold drawing. A strain-hardening or work-hardening region may also occur due to the strength enhancement caused by plastic deformation.
Finally, material will eventually fracture. Fine powders often exhibit significant two-phase i. Flow of fine powders is very complex and generally more difficult to handle. Flow refers to the deformation of powder bed under shear stresses. Powder flow is a reflection of the mechanical behavior of powder under relatively low shear stresses.
On the contrary, powder compaction is a revelation of the mechanical properties of powder under much higher compressive pressures. During flow, the powders gain sufficient shear force such that they can overcome the inter-particulate interactions and frictions and move along the direction of shear. Intuitively, the flowability of bulk powder is dependent on the inter-particulate attractions.
Because of the multi-component nature of formulated powders, the attractive forces between individual particles are often called adhesive forces. However, interactions among particles of the same kind should be more correctly termed as cohesion. Van der Waals interaction is primarily responsible for these inter-particulate forces, which include dipole-dipole Keesom force , dipole-induced dipole Debye force , and induced dipole-induced dipole dispersion or London force interactions.
The number of particle contacts is another important factor in the inter-particulate interactions of bulk powder. Perfectly spherical particles have the least possible number of contacts and are usually the most readily flowable. Most pharmaceutical powders are irregularly shaped. The number of contacts is generally higher and contacting faces may even be possible.
Smaller particles have relatevely higher numbers of contacts and the total adhesive forces are greater. As a rule, fine powder generally flows more poorly than large particle size powder. Increased inter-particulate interactions may also result from particle bridging.
Particle bridging may be caused by physical locking, or by crystallization following partial dissolution, by sintering around the contact points, by plastic deformation at the particle contacts, or by various other physical, chemical, or biological processes.
Powder flowability is a consequence of the inter-particulate interactions. From a material science point of view, this interparticulate interaction depends on chemistry, crystal structure, and powder structure. Certain powder structures may be altered by mechanical forces. Application of external forces can increase the number of particle contacts, cause plastic deformation around the contacts, and increases the contact area. These in turn lead to a change in the overall adhesiveness, the powder structure, and flow characteristics.
Even without external forces, bulk powder during storage will consolidate under gravity, which is called timed consolidation. It is a revelation of the viscoelasticity of the powder. Timed consolidation causes increased particle-particle interaction and may eventually lead to caking, which significantly alters the flow behavior.
In brief, the easiness of powder flow depends strongly on the interparticulate interactions in the powder, the latter of which is determined by molecular structure, crystal structure, and powder structure. The stronger the interparticulate interaction, the less flowable is the powder, and the more shear is required to render flow.
Powder Flow PatternAdequate powder flowability is key to the success of many unit operations in the manufacture of solid products. Powder flow properties are known to influence the fluidization behavior in the granulation and drying operation and mixing during blending operation.
However, it also has a significant impact on tablet compression or encapsulation. Consistently good flowability is critical in producing quality tablets and capsules. Typical issues related to powder flow are caused by poor flow of materials in the bins, through hoppers, or into die cavities. Powder flow pattern in a hopper may be classified as mass flow or funnel flow Figure 4.
Show all documents The significance of collective role of QbD and PAT Tools in the Pharmaceutical Process Automation A planned set of controls, derived from current product and process understanding that ensures process performance and product quality. The con- trols can include parameters and attributes related to drug substance and drug product materials and components, facility and equipment operating conditions, in- process controls, finished product specifications, and the associated methods and frequency of monitoring and control ICH Q Based on the process design space, a well-executed control strategy can be defined. This enables to understand the processes in a way that ensures product quality from known variability of the pro- duction process. This disciplined approach will keep the complex production processes under con- trol. One technique to help avoid such a disparity is to conduct a Design of Experiments DOE study on the product in the development stage.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Sundin Published Engineering. Remanufacturing is an industrial process where used products are restored to useful life. This dissertation describes how products can be designed to facilitate the remanufacturing process. It also Save to Library.
Смит был прав. Между деревьев в левой части кадра что-то сверкнуло, и в то же мгновение Танкадо схватился за грудь и потерял равновесие. Камера, подрагивая, словно наехала на него, и кадр не сразу оказался в фокусе. А Смит тем временем безучастно продолжал свои комментарии: - Как вы видите, у Танкадо случился мгновенный сердечный приступ. Сьюзан стало дурно оттого, что она увидела.
Шифр не поддается взлому, - сказал он безучастно. Не поддается. Сьюзан не могла поверить, что это сказал человек, двадцать семь лет работавший с шифрами. - Не поддается, сэр? - с трудом произнесла. - А как же принцип Бергофского. О принципе Бергофского Сьюзан узнала еще в самом начале своей карьеры.
Чатрукьян знал и то, что выключить ТРАНСТЕКСТ можно двумя способами. Первый - с личного терминала коммандера, запертого в его кабинете, и он, конечно, исключался. Второй - с помощью ручного выключателя, расположенного в одном из ярусов под помещением шифровалки.
Телефон звонил не переставая. Джабба решил не обращать на него внимания. - Мидж, - беззвучно выдавил он, - черт тебя дери. В шифровалке все в порядке! - Телефон не унимался. Джабба принялся устанавливать на место новый чип.
Он сам был своим партнером. Никакой Северной Дакоты нет и в помине. Энсей Танкадо - единственный исполнитель в этом шоу. Единственный исполнитель. Сьюзан пронзила ужасная мысль.
Он жертвует всеми планами, связанными с Цифровой крепостью. Хейл не мог поверить, что Стратмор согласился упустить такую возможность: ведь черный ход был величайшим шансом в его жизни. Хейлом овладела паника: повсюду, куда бы он ни посмотрел, ему мерещился ствол беретты Стратмора. Он шарахался из стороны в сторону, не выпуская Сьюзан из рук, стараясь не дать Стратмору возможности выстрелить. Движимый страхом, он поволок Сьюзан к лестнице.
Акт безжалостного уничтожения. Бесчувственная демонстрация силы страной, уже добившейся победы. С этим Танкадо сумел примириться. Но он не смог примириться с тем, что этот взрыв лишил его возможности познакомиться с собственной матерью.
Это была шутка, Мидж. - Но он знал, что сказанного не вернешь. ГЛАВА 62 Коммандер и Сьюзан стояли у закрытого люка и обсуждали, что делать. - Итак, внизу у нас погибший Чатрукьян, - констатировал Стратмор. - Если мы вызовем помощь, шифровалка превратится в цирк.
Увы, она уже знала ответ. Так вот какова месть Танкадо.
Like workers in thermodynamics; momentum, heat, and mass transfer; and chemical reaction kinetics, product and process designers apply the principles of.Hilaire G. 18.05.2021 at 01:23
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