Simultaneous removal of CO2, SO2, and NOx from flue gas by liquid phase dehumidification at cryogenic temperatures and low pressure

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Advanced Vadose Zone Simulations Using TOUGH

The vadose zone can be characterized as a complex subsurface system in which intricate physical and biogeochemical processes occur in response to a variety of natural forcings and human activities. This makes it difficult to describe, understand, and predict the behavior of this specific subsurface system. The TOUGH nonisothermal multiphase flow simulators are well-suited to perform advanced vadose zone studies. The conceptual models underlying the TOUGH simulators are capable of representing features specific to the vadose zone, and of addressing a variety of coupled phenomena. Moreover, the simulators are integrated into software tools that enable advanced data analysis, optimization, and system-level modeling. We discuss fundamental and computational challenges in simulating vadose zone processes, review recent advances in modeling such systems, and demonstrate some capabilities of the TOUGH suite of codes using illustrative examples

Measurement of adsorption of a single component from the liquid phase : modelling investigation and sensitivity analysis

In this work, we consider an alternative approach for the measurement of adsorption from the liquid phase. Consider a mixture consisting of a non-adsorbed component (B) and an adsorbed component (A) present at some low concentration. Initially, a feed of component B only flows through a column packed with an adsorbent. Then, the feed is switched to the mixture of A and B. As soon as the mixture enters the column, there will be a reduction in the outlet flow rate as component A leaves the liquid phase and passes into the adsorbed phase. There are three stages to this work. The first is to develop overall and component balances to show how the amount adsorbed of component A can be determined from the variation in the column outlet flow rate. The second is to determine the actual variation in the column outlet flow rate for both plug flow and axial-dispersed plug flow. The final stage is to consider the suitability of a gravity-fed system to deliver the feed to the column. An analysis of the results shows that the experimental arrangement should be able to accurately monitor adsorption from the liquid phase where the mass fraction of the solute is of the order of 1%: the limiting experimental factor is how constant the volumetric flow rate of the liquid feed can be maintained

Process feasibility study in support of silicon material, Task I. Quarterly technical progress report (XVIII), December 1, 1979-February 29, 1980

Analyses of process system properties were continued for important chemical materials involved in the several processes under consideration for semiconductor and solar cell grade silicon production. Major activities were devoted to physical, thermodynamic and transport property data for silicon. Property data are reported for vapor pressure heat of vaporization, heat of sublimation, liquid heat capacity and solid heat capacity as a function of temperature to permit rapid usage in engineering. Chemical engineering analysis of the HSC process (Hemlock Semiconductor Corporation) for production of silicon was initiated. The process is based on hydrogen reduction of dichlorosilane (DCS) to produce the polysilicon. The chemical vapor deposition reaction for DCS is faster in rate than the conventional process route which utilizes trichlorosilane (TCS) as the silicon raw material. Status and progress are reported for primary activities of base case conditions (30%), reaction chemistry (25%) and process flow diagram (20%). Discussions with HSC and construction of a process flow diagram are in progress. Preliminary economic analysis of the BCL process (case B) was completed. Cost analysis results are presented based on a preliminary process design of a plant to produce 1000 metric tons/year of silicon. Fixed capital investment for the plant is $14.35 million (1980 dollars) and product cost without profit is 11.08$/kg of silicon (1980 dollars). Cost sensitivity analysis indicate that the product cost is influenced most by plant investment and least by labor. For profitability, a sales price of 14 $/kg (1980 dollars) gives a 14% DCF rate of return on investment after taxes

Process feasibility study in support of silicon material task 1. Quarterly technical progress report (XX), June 1-August 31, 1980

Analyses of process system properties were continued for chemical materials important in the production of silicon including compilation and collection activities of the property data for use in the final report. Major efforts in chemical engineering analysis centered on the DCS process - Case A which involves production of dichlorosilane (DCS) as a silicon source material for polysilicon production in the Hemlock Semiconductor Corporation program. The preliminary process design of a plant to produce DCS was completed including process flowsheet (100%), base case conditions (100%), reaction chemistry (100%), raw materials (100%), utilities (100%), major process equipment (100%) and production labor (100%). The process design package was forwarded for economic analysis. Economic analysis of the DCS process - Case A was completed during this reporting period. The results for dichlorosilane (DCS) indicated a total product cost without profit of 1.29 $/kg (1980 dollars). This product cost without profit includes direct manufacturing cost, indirect manufacturing cost, plant overhead and general expenses. The sales price of DCS at 15$/kg (1980 dollars). Additional results are reported for sales price of dichlorosilane at various profitability levels as measured by ROI (return on original investment) and DCF (discounted cash flow rate of return)

Process feasibility study in support of silicon material Task I. Quarterly technical progress report (XIX), March 1-May 31, 1980

Analyses of process system properties were continued for chemical materials important in the production of silicon. Major physical, thermodynamic and transport property data are reported for silicon including critical constants, vapor pressure, heat of vaporization, heat of sublimation, heat capacity, density, surface tension, viscosity and thermal conductivity. The property data covers both liquid and solid phases and are reported as a function of temperature for rapid engineering usage. Major efforts in chemical engineering analysis centered on the HSC process (Hemlock Semiconductor Corporation). The approach for the process involves performing initial analysis for DCS production (dichlorosilane) and then perorming analysis of polysilicon production from the DCS. For the DCS production, status and progress are reported for primary activities of base case conditions (65%), reaction chemistry (65%), process flowsheet (60%), material balance (50%) and energy balance (40%). Two key features - redistribution reactor relocation and final distillation - are introduced to increase yield of DCS by about 10 to 20%, help insure purity and reduce potential dust (fine particle nucleation) components in the polysilicon feed material. The preliminary flowsheet for DCS production was forwarded to Hemlock Semiconductor Corporation for initial screening and review. Hemlock Semiconductor is in agreement in regards to relocation of the redistribution reactor to increase yield. Additional follow-up review is in progress including boron removal options identified by Hemlock Semiconductor. 166 references