Kuyen Li

New technologies for solar energy silicon - Cost analysis of dichlorosilane process

Abstract New technologies for producing polysilicon are being developed to provide lower cost material for solar cells which convert sunlight into electricity. This article presents results for the UCC Silane Process (Union Carbide Corporation Silane Process). Other processes being developed will be presented in forthcoming articles. Cost, sensitivity and profitability analysis results are presented based on a preliminary process design of a plant to produce 1000 metric tons/yr of silicon by the UCC Silane Process. The profitability results indicate a sales price of 9.88

Flare minimisation via dynamic simulation

/kg of silicon (1975 dollars) at a 20 per cent DCF return on investment after taxes. These results indicate good potential for meeting the 1975 LSA cost goal of

Cyclic scheduling for best profitability of industrial cracking furnace system

10 per kg.

Photocatalytic oxidation of butyraldehyde over titania in air: By-product identification and reaction pathways

This paper describes a project of flare minimisation during plant startup by using dynamic simulation. Dynamic simulation was developed for recovery area in an olefin plant and used to examine startup procedures: • approaching shutdown • startup with recycle ethane • starting the cracked feed and increasing the feed to normal production rate. The dynamic simulation gives an insight into the process dynamic behaviour that is not apparent through the use of steady state simulation. This information is crucial for plant startup in order to minimise the flaring. This project demonstrated a feasibility of pollution prevention through flare minimisation for an olefin plant.

PHOTOCATALYTIC OXIDATION OF ALDEHYDES/PCE USING POROUS ANATASE TITANIA AND VISIBLE-LIGHT-RESPONSIVE BROOKITE TITANIA

An ethylene plant employs multiple cracking furnaces in parallel to convert various hydrocarbon feedstocks to smaller hydrocarbon molecules, mostly ethylene and propylene. The continuous operational performance of cracking furnaces gradually decays because of coke formation in the reaction coils, which requires each furnace to be periodically shut down for decoking. Given multiple feeds and different cracking furnaces as well as various product prices and manufacturing costs, the operational scheduling for the entire furnace system should be optimized to achieve the best economic performance. In this paper, a new MINLP (mixed-integer nonlinear programming) model has been developed to obtain cyclic scheduling strategies for cracking furnace systems. Compared to previous studies, the new model has more capabilities to address operation profitability of multiple feeds cracked in multiple furnaces. Meanwhile, it inherently avoids unpractical conditions such as simultaneous shutdown of multiple furnaces. Case studies demonstrate the efficacy of the developed methodology.

Water-related matrix isolation phenomena during NO2 photolysis in argon matrix.

In this study, gas phase photocatalytic oxidation (PCO) of n-butyraldehyde was carried out in a packed-bed reactor (titania supported on an inert packing). An on-line system consisting of two collection columns (one glass bead and one activated carbon) and a GC/MS was used for by-product identification. Various temperature levels (50, 90, 115, 170, 270, 320°C) were used in the by-product desorption from the activated carbon column. The oxidation yielded carbon dioxide as the end product. The by-products revealed many reaction pathways of the photocatalytic process. The major by-products (propionaldehyde, 1-propanol, ethanol, and acetaldehyde) were believed to undergo a C-C bond cleavage followed by hydrolysis. Secondary by-products (propyl formate, di-n-propyl ether, and 3-heptene) were caused by esterification, dehydration, and reductive coupling. Aldol condensation of the vapor phase aldehydes on TiO 2 surfaces followed by cyclization may be partially responsible for the formation of some minor by-products such as ethylbenzene.

Solubility parameter and liquid volume—Inorganic compounds

We have synthesized an annealed porous aerogel titania (LUAG2), which demonstrates a very high photocatalytic activity for aldehydes and perchloroethylene (PCE) photocatalytic oxidation (PCO) in gas phase under blacklight and fluorescent light irradiation. LUAG2 has a BET surface area of 237 m2/g and a porosity of 0.31 (volume fraction). X-ray diffraction (XRD) analysis shows LUAG2 is nearly pure anatase. It has improved the destruction of PCE and aldehydes as a group by 10–34% with black light compared to Degussa P-25. The optimum water vapor to butyraldehyde molar ratio is around 1/3. LUAG2 also shows better mineralization to CO2 than Degussa P-25 TiO2 does. Under irradiation of a 4 W fluorescent lamp LUAG2 gives a consistently higher conversion than that of Degussa P-25. The highly active photocatalyst indicates potential applications in indoor and outdoor environmental pollution control. A visible-light-responsive TiO2, NTB 200, is also investigated for comparison purposes.

Fourier Transform Infrared-Probed O(3P) Microreactor: Demonstration with Ethylene Reactions in Argon Matrix

Photolysis (350–450 nm) of NO2 molecules trapped in argon matrices at 10 K has been studied using Fourier transform infrared (FT-IR) spectroscopy to examine the mobility of the photolysis products, O(3P) and NO, and their subsequent reactions. The formation of N2O5 and N2O3 from reactions of these mobile species with immobilized NO2 and N2O4 is confirmed. Water molecules from the background gases in the vacuum have been found to be isolated in the argon matrix during deposition of diluted NO2 in Ar. The entrapped water molecules along with some of their NO2 adducts have been characterized. Exposure of the matrix to photons to photolyze NO2 resulted in not only internal matrix reactions, but also an enhanced deposition of ice over the surface of the argon matrix. This is caused by photodesorption of water molecules from the walls of the matrix isolation chamber and their subsequent condensation on the matrix surface. This ice overlayer has been found to give a very significant dangling OH band and a substantial librational band in the FT-IR spectra, indicating substantial surface area and internal porosity, respectively. The potential of using photodesorbed water to establish high surface area ice interfaces with dangling OH groups for heterogeneous photoreaction studies is discussed.

ENHANCEMENT FACTOR OF GAS ABSORPTION ACCOMPANIED BY REVERSIBLE CYCLIC CHEMICAL REACTIONS

Publisher Summary This chapter presents the solubility parameter and liquid volume for organic compounds in tabular form. The tabulation is arranged by carbon number such as C, C2, and C3, to provide ease of use in quickly locating the data by using the chemical formula. The compound name and chemical abstracts registry number (CAS No) are also provided in columns. Values for solubility parameter and liquid volume are given in the adjacent columns. The next column provides the code for the tabulation. For the tabulation, the results for solubility parameter are ascertained from heat of vaporization and liquid volume. In preparing the tabulation, a literature search is conducted to identify data source publications. Both experimental values for the property under consideration and parameter values for estimation of the property are included in the source publications. The publications are screened, and copies of appropriate data are made. These data are keyed into the computer to provide a database of values for compounds for which experimental data are available. The database also serves as a basis to check the accuracy of the estimation methods. Upon completion of data collection, estimation of values for the remaining compounds is performed. The compilations of CRC, Daubert and Danner, TRC, and Yaws are used extensively. Estimates for the enthalpy of vaporization at the boiling point are primarily based on the Kistiakowsky rule and Riedel method. The Joback method is used for estimating critical temperature. Estimates of liquid density are primarily based on the Schroeder correlation, Le Bas method, and Tyn-Calus equation. Liquid volume is ascertained from molecular weight and liquid density (molecular weight/density).

CFD Simulation of Confined Non-Premixed Flames

To demonstrate the development of an oxygen atom microreactor in the form of liquid-helium-cooled solid argon matrix deposited on an infrared (IR) window, the oxidation of ethylene by mobile O atoms has been investigated. O atom diffusion through the argon matrix is confirmed and used to examine ethylene–oxygen atom reactions. In a bench-scale matrix isolation system probed with a Fourier transform infrared (FT-IR) spectrometer, matrices of solid Ar at 8–10 K doped with NO2 and ethylene have been prepared on a ZnSe window within an evacuated cryostat. The matrices have been photolyzed using 350–450 nm photons, and the reaction products resulting from the reaction of O(3P), one of the photolysis products of NO2, with ethylene have been identified using FT-IR and a Gaussian 98W simulation program. These products include oxirane, acetaldehyde, ethyl nitrite radical, and ketene. The temperature effect in the range of 10–30 K on the products formed has also been investigated. The reaction mechanisms are discussed and the viability of the solid Ar matrix being a low temperature microreactor to examine reaction mechanisms of mobile oxygen atoms is elaborated.