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Distillation is undoubtedly the most important unit operation in chemical engineering. During design a significant effort is normally put into steady-state optimization of the column with respect to its size, feed location and reflux ratio. However, operating the column close to this optimal point requires reasonably tight control of the product compositions. This is usually not achieved in industrial practice due to stability problems. Improved strategies for distillation control offer a viable means for significant economic savings as compared to the existing ad hoc techniques. This thesis addresses robust control of distillation columns in the face of model-plant mismatch caused by model uncertainty, nonlinearity and changes in operating conditions. The robust control paradigm, introduced by Doyle and coworkers, is used as the basis for controller design and analysis. An important tool is the Structured Singular Value (SSV) which enables the evaluation of a plant's achievable control performance. This provides a consistent basis for comparing controllers and design alternatives. Achievable performance is also related to other commonly used measures such as the RGA and the condition number.

Distillation is undoubtedly the most important unit operation in chemical engineering. During design a significant effort is normally put into steady-state optimization of the column with respect to its size, feed location and reflux ratio. However, operating the column close to this optimal point requires reasonably tight control of the product compositions. This is usually not achieved in industrial practice due to stability problems. Improved strategies for distillation control offer a viable means for significant economic savings as compared to the existing ad hoc techniques. This thesis addresses robust control of distillation columns in the face of model-plant mismatch caused by model uncertainty, nonlinearity and changes in operating conditions. The robust control paradigm, introduced by Doyle and coworkers, is used as the basis for controller design and analysis. An important tool is the Structured Singular Value (SSV) which enables the evaluation of a plant's achievable control performance. This provides a consistent basis for comparing controllers and design alternatives. Achievable performance is also related to other commonly used measures such as the RGA and the condition number.

The object of this research was to study quantitatively possibilities of a continuous process of production of perchloric acid from nitrogen peroxide and ammonium perchlorate. Perchloric acid has many properties which make it an important acid in industrial and analytical work and its use would be much greater if its cost of production could be lowered. It is a strong monobasic acid, stable in solutions (up to 60%), has a high boiling point. There are relatively few insoluble salts (potassium, rubidium, caesium, and thallium perchlorates are only highly soluble) and the difference in solubilities of potassium and sodium perchlorates give an easy method of separation of these two metals in analytical work.

The object of this research was to study quantitatively possibilities of a continuous process of production of perchloric acid from nitrogen peroxide and ammonium perchlorate. Perchloric acid has many properties which make it an important acid in industrial and analytical work and its use would be much greater if its cost of production could be lowered. It is a strong monobasic acid, stable in solutions (up to 60%), has a high boiling point. There are relatively few insoluble salts (potassium, rubidium, caesium, and thallium perchlorates are only highly soluble) and the difference in solubilities of potassium and sodium perchlorates give an easy method of separation of these two metals in analytical work.

Zeolite and molecular sieve materials are broadly used as ion-exchangers, adsorbents and catalysts in the chemical industry. Zeolites are typically synthesized by using organic molecules as structure-directing agents (SDA). The SDA should be removed from the pore cavity of the zeolite framework to create microporous void space before the zeolite can be used for further purposes. Porous zeolites have been prepared by calcination, or extraction in very limited cases.

Zeolite and molecular sieve materials are broadly used as ion-exchangers, adsorbents and catalysts in the chemical industry. Zeolites are typically synthesized by using organic molecules as structure-directing agents (SDA). The SDA should be removed from the pore cavity of the zeolite framework to create microporous void space before the zeolite can be used for further purposes. Porous zeolites have been prepared by calcination, or extraction in very limited cases.

Pickling liquor is nothing more than dilute sulfuric acid used in the iron and steel industry for removing scales on the surface of iron work which is to be further treated. The reaction for pickling may be represented by the equation FeO + H2SO4 = FeSO4 + H2O. Thus we see from this equation that H2SO4 is gradually used up and FeSO4 formed during the process. It is evident, then, after a certain length of time, H2SO4 will be too valuable to be cast away. This FeSO4 may be converted into an oxide which is a pigment, or taken out in the form of FeSO4.7H2O crystals. The latter is the purpose of this work. FeSO4 has the following uses: photography; writing ink; Prussian blue; preparation of iron oxide for illuminating gas purification; water purification; medicine; disinfectant; textile and leather industries; analytical reagent; making other iron salts.

Pickling liquor is nothing more than dilute sulfuric acid used in the iron and steel industry for removing scales on the surface of iron work which is to be further treated. The reaction for pickling may be represented by the equation FeO + H2SO4 = FeSO4 + H2O. Thus we see from this equation that H2SO4 is gradually used up and FeSO4 formed during the process. It is evident, then, after a certain length of time, H2SO4 will be too valuable to be cast away. This FeSO4 may be converted into an oxide which is a pigment, or taken out in the form of FeSO4.7H2O crystals. The latter is the purpose of this work. FeSO4 has the following uses: photography; writing ink; Prussian blue; preparation of iron oxide for illuminating gas purification; water purification; medicine; disinfectant; textile and leather industries; analytical reagent; making other iron salts.

The object of this investigation has been to determine a method to extract lithium from its ores in order to produce Li2CO3 which is used in medicine. Lithium salts command very good prices (averaging about $1.50 per pound) and a simple method of production would form a successful commercial enterprise. Lithium occurs in lepidolite (a lithium mica) and in amblygonite and other moderately rare minerals. In Southern California there are deposits of lepidolite with which this work has been conducted.

The object of this investigation has been to determine a method to extract lithium from its ores in order to produce Li2CO3 which is used in medicine. Lithium salts command very good prices (averaging about $1.50 per pound) and a simple method of production would form a successful commercial enterprise. Lithium occurs in lepidolite (a lithium mica) and in amblygonite and other moderately rare minerals. In Southern California there are deposits of lepidolite with which this work has been conducted.

This investigation was undertaken to find the best method of preparing oxalic acid from sawdust, either by one of the methods described in the literature or a modification of it. The first work consisted in following the procedure recommended by a previous experimenter in order to become acquainted with the methods which are now used and to discover their weak points. The procedures used commercially, and the experimental work of Thorn, described in "Utilization of Wood Waste" by E. Hubbard form the basis of the work. No recent literature could be found on the subject, the work of Thorn having been done nearly forty years before. Various commercial processes use slightly different methods; one uses KOH alone in the fusion and precipitates MgC2O4 by adding MgCl2 to the K2C2O4 solution; in another a preliminary fusion is carried on in a vacuum at 180°, followed by the regular fusion yielding a nearly colorless product. A process similar to that outlined by Thorn is also used.

The heating of sawdust with KOH results in the production of oxalic acid. Since NaOH is much cheaper, it is desirable to substitute it for KOH as far as possible. Thorn found that a mixture containing 40% KOH and 60% NaOH by weight gave almost as good a yield, when heated in thin layers, as pure KOH. The yield dropped off rapidly with a decreasing KOH percentage below 40%. He also found that the most satisfactory melt was made by using one part of sawdust to two parts of lye, striking a balance between large percentage yield from lye with more sawdust, and more organic impurities which are hard to remove if more sawdust is used. Soft wood gives a better yield than hardwood, and pure sawdust gives a better one than lignose left after treating cellulose with HC1

This investigation was undertaken to find the best method of preparing oxalic acid from sawdust, either by one of the methods described in the literature or a modification of it. The first work consisted in following the procedure recommended by a previous experimenter in order to become acquainted with the methods which are now used and to discover their weak points. The procedures used commercially, and the experimental work of Thorn, described in "Utilization of Wood Waste" by E. Hubbard form the basis of the work. No recent literature could be found on the subject, the work of Thorn having been done nearly forty years before. Various commercial processes use slightly different methods; one uses KOH alone in the fusion and precipitates MgC2O4 by adding MgCl2 to the K2C2O4 solution; in another a preliminary fusion is carried on in a vacuum at 180°, followed by the regular fusion yielding a nearly colorless product. A process similar to that outlined by Thorn is also used.

The heating of sawdust with KOH results in the production of oxalic acid. Since NaOH is much cheaper, it is desirable to substitute it for KOH as far as possible. Thorn found that a mixture containing 40% KOH and 60% NaOH by weight gave almost as good a yield, when heated in thin layers, as pure KOH. The yield dropped off rapidly with a decreasing KOH percentage below 40%. He also found that the most satisfactory melt was made by using one part of sawdust to two parts of lye, striking a balance between large percentage yield from lye with more sawdust, and more organic impurities which are hard to remove if more sawdust is used. Soft wood gives a better yield than hardwood, and pure sawdust gives a better one than lignose left after treating cellulose with HC1

Due to the fact that perchloric acid resembles sulfuric acid in many respects without having many of the disadvantages of use possessed by the latter, the devising of a cheaper means of producing it would be well warranted by its increased use in both analytical and industrial work. The present work was undertaken with the above idea in view and consisted in studying quantitatively the reaction taking place between nitric oxide (NO), nitric acid, and ammonium perchlorate.

Anhydrous perchloric acid is an unstable compound, decomposing spontaneously after a few weeks even when kept in the dark. It is a violently reacting oxidizing agent for many organic substances but aqueous solutions of the acid are not affected by light and are not active oxidizing agents.

Perchloric acid solutions (60% strength being the standard commercial form of the acid) are strong, mono-basic solutions which are stable up to the 60% strength and have high boiling points. The salts which the acid forms are nearly all soluble, the potassium, rubidium, caesium and thallium perchlorates being the only ones which are only slightly soluble. This would recommend it over sulfuric acid in many cases where insoluble salts of the latter prevent its use or cause it to seriously interfere on this account in analytical determinations. Also the difference in the solubilities of the potassium and sodium salts permits an easy separation of the perchlorates of these two metals. The maximum boiling point of aqueous solutions at atmospheric pressure is 203° C., which corresponds to a constant boiling mixture having a perchloric acid content of 72.3%. Below 160°C. the distillate contains less than 1% of perchloric acid. Most perchlorates are deliquescent except ammonium, potassium, lead and mercury salts.

There have been a number of processes devised for the production of perchloric acid, some of which are only of theoretical importance, but the following methods are the ones which have been used to some extent commercially:

Due to the fact that perchloric acid resembles sulfuric acid in many respects without having many of the disadvantages of use possessed by the latter, the devising of a cheaper means of producing it would be well warranted by its increased use in both analytical and industrial work. The present work was undertaken with the above idea in view and consisted in studying quantitatively the reaction taking place between nitric oxide (NO), nitric acid, and ammonium perchlorate.

Anhydrous perchloric acid is an unstable compound, decomposing spontaneously after a few weeks even when kept in the dark. It is a violently reacting oxidizing agent for many organic substances but aqueous solutions of the acid are not affected by light and are not active oxidizing agents.

Perchloric acid solutions (60% strength being the standard commercial form of the acid) are strong, mono-basic solutions which are stable up to the 60% strength and have high boiling points. The salts which the acid forms are nearly all soluble, the potassium, rubidium, caesium and thallium perchlorates being the only ones which are only slightly soluble. This would recommend it over sulfuric acid in many cases where insoluble salts of the latter prevent its use or cause it to seriously interfere on this account in analytical determinations. Also the difference in the solubilities of the potassium and sodium salts permits an easy separation of the perchlorates of these two metals. The maximum boiling point of aqueous solutions at atmospheric pressure is 203° C., which corresponds to a constant boiling mixture having a perchloric acid content of 72.3%. Below 160°C. the distillate contains less than 1% of perchloric acid. Most perchlorates are deliquescent except ammonium, potassium, lead and mercury salts.

There have been a number of processes devised for the production of perchloric acid, some of which are only of theoretical importance, but the following methods are the ones which have been used to some extent commercially:

Future ultrahigh efficiency multijunction solar cells will employ designs that feature three or four or more subcells utilizing lattice-mismatched structures to achieve an optimal band gap sequence for solar energy conversion. While lattice-mismatched multijunction cells have been fabricated recently using metamorphic growth approaches, use of direct wafer bonding techniques to enable lattice mismatch accommodation at the subcell interfaces allows considerably more design freedom and inherently higher-quality, defect-free active regions.

Future ultrahigh efficiency multijunction solar cells will employ designs that feature three or four or more subcells utilizing lattice-mismatched structures to achieve an optimal band gap sequence for solar energy conversion. While lattice-mismatched multijunction cells have been fabricated recently using metamorphic growth approaches, use of direct wafer bonding techniques to enable lattice mismatch accommodation at the subcell interfaces allows considerably more design freedom and inherently higher-quality, defect-free active regions.

This chemical engineering ebook discusses findings gained through work with the NOx abatement system at Radford Facility and Army Ammunition Plant (RFAAP). Removal of harmful substances from flue-gas emissions has garnered increased priority in the chemical industry in preceding decades, as governmental restrictions on these substances become more stringent and as national awareness concerning environmental quality and resource utilization continues to grow. These reasons make the study of NOx abatement an important and challenging endeavor. This work concerns itself specifically with reduction of NOx in flue-gas emissions from stationary sources. First we present an overview of current technology and approaches to controlling NOx for stationary sources. Next, we focus in on one particular approach to control of NOx within the context of a case study of the technology used at the Radford Facility and Army Ammunition Plant. RFAAP employs a scrubber/absorber tower followed in series by a selective catalytic reduction (SCR) reaction vessel in their NOx abatement system. We use as the method of study computer simulations within ASPEN Plus, a process simulation software package for chemical plants. We develop three different models with which to characterize NOx abatement at RFAAP, a conversion model, an equilibrium model and a kinetic model. The conversion-reaction model approximates the absorption and SCR reactions with constant percentage extent-of-reaction values. Though useful for initial investigation and mass balance information, we find the conversion model's insensitivity to process changes to be unacceptable for in-depth study of the case of NOx absorption and SCR. The equilibrium-reaction model works on the assumption that all the reactions reach chemical equilibrium. For the conditions studied here, we find the equilibrium model accurately simulates NOx absorption but fails in the case of SCR. Therefore, we introduce a kinetic-reaction model to handle the SCR. The SCR reactions prove to be highly rate-dependant and the kinetic approach performs well. The final evolution of the ASPEN Plus simulation uses an equilibrium model for the absorption operation and a kinetic model for the SCR. We explore retrofit options using this combined model and propose process improvements. We end this work with observations of the entire project in the form of conclusions and recommendations for improving the operation of the NOx abatement system through process-parameter optimization and equipment-retrofit schemes.

This chemical engineering ebook discusses findings gained through work with the NOx abatement system at Radford Facility and Army Ammunition Plant (RFAAP). Removal of harmful substances from flue-gas emissions has garnered increased priority in the chemical industry in preceding decades, as governmental restrictions on these substances become more stringent and as national awareness concerning environmental quality and resource utilization continues to grow. These reasons make the study of NOx abatement an important and challenging endeavor. This work concerns itself specifically with reduction of NOx in flue-gas emissions from stationary sources. First we present an overview of current technology and approaches to controlling NOx for stationary sources. Next, we focus in on one particular approach to control of NOx within the context of a case study of the technology used at the Radford Facility and Army Ammunition Plant. RFAAP employs a scrubber/absorber tower followed in series by a selective catalytic reduction (SCR) reaction vessel in their NOx abatement system. We use as the method of study computer simulations within ASPEN Plus, a process simulation software package for chemical plants. We develop three different models with which to characterize NOx abatement at RFAAP, a conversion model, an equilibrium model and a kinetic model. The conversion-reaction model approximates the absorption and SCR reactions with constant percentage extent-of-reaction values. Though useful for initial investigation and mass balance information, we find the conversion model's insensitivity to process changes to be unacceptable for in-depth study of the case of NOx absorption and SCR. The equilibrium-reaction model works on the assumption that all the reactions reach chemical equilibrium. For the conditions studied here, we find the equilibrium model accurately simulates NOx absorption but fails in the case of SCR. Therefore, we introduce a kinetic-reaction model to handle the SCR. The SCR reactions prove to be highly rate-dependant and the kinetic approach performs well. The final evolution of the ASPEN Plus simulation uses an equilibrium model for the absorption operation and a kinetic model for the SCR. We explore retrofit options using this combined model and propose process improvements. We end this work with observations of the entire project in the form of conclusions and recommendations for improving the operation of the NOx abatement system through process-parameter optimization and equipment-retrofit schemes.

Over the last century, energy consumption has increased tremendously due to the growth of world population and industrialization. Interest in the utilization of renewable carbohydrate sources to produce fuel ethanol as an alternative to petroleum is rising around the world to save petroleum and natural gas. The ideal raw materials for ethanol production should be cheap and rich in nutrient. Some renewable feedstock such as sago starch, cellulose materials have been investigated. Few researches are carried out on the utilization of kitchen garbage.

Being a kind of municipal waste with high volume, kitchen garbage is difficult to be handled owning to its high organic content and moisture. On the other hand, it could also be regarded as a valuable resource
due to its content of nutrients. It is reported that hydrogen, lactic acid and other substances could be produced from it. The research taken on by Li12 adopted the organic solid based on European
standard to produce ethanol. The raw materials were a mixture of waste from kitchen garbage and yard waste. Little information showed the utilization of Chinese kitchen garbage, since Chinese have a unique eating habit, the investigation on Chinese kitchen garbage to ethanol could provide valuable information for the recycling technology.

Over the last century, energy consumption has increased tremendously due to the growth of world population and industrialization. Interest in the utilization of renewable carbohydrate sources to produce fuel ethanol as an alternative to petroleum is rising around the world to save petroleum and natural gas. The ideal raw materials for ethanol production should be cheap and rich in nutrient. Some renewable feedstock such as sago starch, cellulose materials have been investigated. Few researches are carried out on the utilization of kitchen garbage.

Being a kind of municipal waste with high volume, kitchen garbage is difficult to be handled owning to its high organic content and moisture. On the other hand, it could also be regarded as a valuable resource
due to its content of nutrients. It is reported that hydrogen, lactic acid and other substances could be produced from it. The research taken on by Li12 adopted the organic solid based on European
standard to produce ethanol. The raw materials were a mixture of waste from kitchen garbage and yard waste. Little information showed the utilization of Chinese kitchen garbage, since Chinese have a unique eating habit, the investigation on Chinese kitchen garbage to ethanol could provide valuable information for the recycling technology.