No abstract

The changes to the solid phase which occur within fluidized-bed gas-solid reactors may have a significant impact on the performance of this class of reactors, particularly in coal conversion applications. In this paper a particle balance model is developed which accommodates particle distributions dependent on both size and density as well as populations consisting of multiple solids. The fast double collocation method used for solving the associated PDE permits this calculation to be performed within the framework of a Davidson-Harrison bubbling-bed model. A modification of the iteration procedure for the emulsion-phase state variables of the D-H model is reported which allows the composite reactor model to be executed reliably and efficiently. A general purpose program has been implemented, whose application is presented in a companion paper. W. OVERTURF West Lafayette, IN 47951 CONCEPTUAL REACTOR MODELcomposed only of solids-free gas, and a dense or emulsion phase, consisting of the solid particles and of a volume of gas corresponding to the bed-void fraction at minimum fluidization. The solids transfer heat and mass with the emulsion (or interstitial) gas but not directly with the dilute phase. Although as reviewed inThe conceptual model of a fluidized-bed reactor employed in this work is shown in Figure 1. Following Davidson and Harrison (1963), we assume that the bed consists of a dilute or bubble phase,

The GASP IV combined discrete-continuous stimulation language provides a powerful modelling tool for simulating batch/semicontinuous plants. This paper discusses the salient features of GASP IV and shows its application to a single train process consisting of a batch unit, two semicontinuous units, storage tanks, and stochastic variables. The model of the process is based on the work of Davis and Kermode. The GASP IV model allows the simulation of multiple batch runs to be carried out and shows that the operating policy derived previously is unsatisfactory in the long run.

proposal was resubmitted in November 1975 and the project was initiated on. March 12, 1976 under the aegis of the newly formed ERDA Fossil Demonstration Plants Division. As part of the initial contract task schedule the BIGAS/SRC based 11 Clean Boiler Fuels froin Coal 11 conceptual process was selected as project base case flowsheet. Purdue University proceeded with data gathering activities for this process including meetings with representatives of the Pittsburgh & Midway Coal Company, the ERDA SRC contractor; the Bituminous Coal Research Laboratory, the BIGAS gasifier developer; PERC; IGT; Oak Ridge; the Bureau of Mines, Morgantown, and other relevant data sources. On J~ly 20, 1976 by letter from the contract technical representative, ERDA requested that the CBFC process be abandoned in favor of the conceptual process proposed by the Illinois Coal Gasification Group. This process had been presented to ERDA in response to an RFP for Pipeline Gas Demonstration Plants, and incorporated concepts tested during project COED, involved a proprietary COGAS gasification/combustion section, the proprietary Hail hydrotreating unit, as well as the RMP bulk methanation system. By letter dated August 2, 1976, Purdue University informed ERDA that the change was acceptable but that it would result in a four month delay in project time tables, assuming process data were released to Purdue by the end of August, 1976.-By ~-1ay of the following year such data were still not forthcoming because of complications in the negotiations between (now) DOE and ICGG. At that time, (Contract Amendment Dated 7/7/77 DOE requested, and Purdue agreed, to•~ndertake an additional task under the existing contract. This task involved the formulation of and literature

The GASP IV combined discrete-continuous simulation language is used to model an existing multiproduct, multiple parallel train plant including the ancillary inventory and distribution functions. A heuristic short term production scheduling technique and a mixed integer linear programming based longer term scheduling model are formulated and tested within the framework of the simulation model. The simulation model is further used to carry out debottlenecking studies, to evaluate changes in plant operating policies, and to perform parameter sensitivity studies. This work thus demonstrates the utility of GASP IV combined with MIP scheduling models as tools for the analysis of processes involving batch/semicontinuous operations.