CLEAN PROCESS DESIGN GUIDELINES

Physical Property Predictive Driver
Data for Waste Inventory Factors
Clean Process Advisory System (CPAS) Core Activities
The Design Option Ranking Tool
Recovery of Organics from Fluid Streams Using Adsorption and Distillation
Process Safety and Risk Evaluation Tool
Reactive Chemistry Screening Tool
Development of the Environmental Technologies Design Options Tool (ETDOT)
Environmentally Conscious Design for Construction
Chemical Properties Tool (StEPP)
Environmental Fate and Risk Assessment Tool (EFRAT)
Process Simulation and Control for Waste Minimization

T. N. Rogers, A.A. Kline, D.C. Luehrs, Michigan Technological University. ( References: Loll, 1996; Luehrs, 1995)

Goal: This project focusses on creating structure-based models of adsorption equilibrium and vapor-liquid equilibrium as key elements of an overall physical property prediction resource. It is a companion project to the project entitled: Chemical Properties Tool, described later in this report. More specifically, this project is to deliver 1) a data set of equilibrium capacities for representative organic chemicals adsorbed onto two commercial granular activated carbons, 2) a Linear Solvation Energy Relationship (LSER) model for activated carbon adsorption, and 3) a training and validation data set of vapor pressure data to be used for model development.

Rationale: Existing data sets of high quality, such as the validated AIChE/DIPPR compilations, are limited in the number of chemicals covered and properties included. Computing equipment advances and new structure-based modeling approaches are twin factors opening up an exciting alternative to raw data compilations: predictive methods that vastly extend the limited data sets in use today.

The most common structure-based property models are based on simple, intuitive factors such as trend with respect to carbon number, consistent behavior within a homologous series, or a semi-empirical relationship derived from theory. Such correlations are often suitable for data interpolation and extrapolation, but will not meet the needs of the proposed effort, in general. More sophisticated approaches, such as quantitative structure/activity relationships (QSARs) must be explored if the accuracy of the methods is to be comparable to the level of uncertainty in experimental data. There are many chemical classes for which validated QSAR models would be a major advance.

This project focusses on vapor liquid equilibrium and adsorption equilibrium; more specifically: a QSAR model for pure component vapor pressures, and an LSER based approach to sorption coefficients. The latter has broad appeal in three technology areas: carbon adsorption, separation technologies involving microporous solids such as alumina or silica, and heterogeneous reactions where adsorption onto the catalyst (e.g., a mixed metal oxide) is important.

Pure component vapor pressures are thermodynamically significant as a widely-used standard state for phase equilibrium calculations. As such, they are related to important design parameters such as Henry's law constant and vapor-liquid equilibrium "K-factors". Predicting (and minimizing) vapor emissions of volatile chemicals must be part of any clean process analysis. From theory, Henry's law constant is the product of a solute's infinite dilution activity coefficient and it's pure vapor pressure. The vapor pressure is called the Lewis-Randall standard state of the solute, and being independent of the solvent, it applies to both aqueous and chemical mixtures. As a formal standard state, vapor pressure has a great deal of thermodynamic significance and helps describe the observed hydrophobicity and volatility of many dissolved aqueous contaminants.

Approach: Past experience suggests a LFER (Linear Free Energy Relationship) or LSER approach as the first option to explore with sorption coefficient modeling. Being linear, model coefficients can come directly from multivariable linear regression without the complication of finding a nonlinear global optimum. Methods requiring nonlinear multivariable optimization will draw upon existing software and methods developed under the vapor pressure modeling effort discussed below. Special emphasis will be placed on liquid-phase processes since these are rather poorly characterized at present. This area was the first undertaken as it ties in well with several other adsorption data-containing projects currently underway by other CenCITT researchers, John Crittenden, David Hand and others.

By fitting adjustable parameters to experimental data, QSAR methods can be used to correlate and extend existing data, and can serve to guide additional research and data collection. Because of the emphasis on functional groups rather than whole molecules, data for relatively simple systems (e.g., single chemicals) can, in theory, provide enough information to predict the behavior of multiple contaminants. A QSAR approach will be sought for vapor pressures of hydrophobic organic contaminants. This will improve existing activity coefficient-based models of air-water partitioning by developing a structural model of the standard state vapor pressure. This information will combine with ongoing activity coefficient research, including our Henry's constant work to completely describe air-water partitioning. A revision of UNIFAC being developed under DIPPR sponsorship shows promise for modeling the activity coefficient as a function of chemical structure. It also extends beyond infinite dilution to predict liquid-liquid miscibility limits and distribution coefficients. An ideal application of the combined activity coefficient/vapor pressure model would be to make structure-based predictions for chemicals that are not amenable to (or are too toxic for) experimental studies.

Status: While begun as a multiyear effort based on funding from USEPA National Risk Management Research Laboratory, it has subsequently been cut to a one-year effort. Because of the reduction in overall project length, most of the work to date has been concentrating on the second and third goals listed above. A database of vapor pressure data has been assembled for approximately 650 chemicals. Ten percent of this database has been set aside to be used as a validation data test set. The remainder are being used to develop a structure based group contribution model for the prediction of pure component vapor pressures based on the UNIFAC method. The revised model that will be produced is an improvement over the original version because the number of fragment groups has been increased and the additive parameters have been regressed against a much larger set of experimental vapor pressure values. A paper presentation on this improved model has been accepted for the February 1996 AIChE meeting.

An LSER model has been completed for the adsorption of organic chemicals on activated carbon. LSER parameters for experimental adsorption coefficients were developed for a data set of 363 chemicals assembled from various references, improving on the approach used in past studies. One improvement of the LSER model is the ability to correlate the LSER parameters to physical constants associated with the chemicals, such as polarizability, availability as a hydrogen bond donor or acceptor, and solute molar volume. A journal article based on this model has been accepted for publication by Environmental Science and Technology.

The LSER model is the basis for the work that is underway on equilibrium capacities under item one of our goals. The LSER parameters already developed are being included as some of the components of the free energy relationships being investigated to develop adsorption isotherms for organic solutes in aqueous solutions. The database that has been assembled for the LSER work is being utilized as part of this effort. Currently, we are concentrating on developing an adsorption isotherm model for a single activated carbon. This will be extended at a later date to include other activated carbons as more experimental data becomes available and the adsorption isotherm model is refined.

D.R. Shonnard, A.S. Mayer, Michigan Technological University. (References: Shonnard, 1995b)

Goal: In considering what pollution preventing technology innovations are possible and how to compare them to the "standard" technologies, a means to essentially compare the environmental impact of various unit operations is needed. One method to do this is to create unit operation waste inventory factors (WIFs) which accumulate all non-product outputs, such as fugitive emissions, purge emissions, maintenance-related waste, by-products and other operating parameters for various unit operations. This one year project is intended to assemble basic data elements required to create a WIF data resource.

Rationale: A methodology is needed for choosing the most environmentally benign chemical process design from a number of alternatives. It is highly desirable that such a methodology be based on the risks imposed to both human health and to the environment stemming from the operation of a chemical process. Risk assessment to the environment should be comprehensive, including the effects of pollutant emissions on global warming potential, ozone depletion, acid rain formation, smog generation, groundwater contamination, and accumulation of pollutants in all environmental compartments, including plants and animals. Currently, such an evaluation tool is not available to the chemical process design engineer. This research proposes to provide data critical to developing such a tool for rapid environmental and human health risk assessments and for implementing it within a pollutant assessment and prevention module of a commercially available process simulator.

To facilitate the comparison of various equipment configurations and selections, it would be desirable to correlate this data by unit operation. It is expected that if correlated in this way, it would find uses in economic comparisons as well as environmental impact. For example, the generation of a greenhouse gas, such as carbon dioxide, can often be correlated to combustion efficiency. In cases where the process involves combustion of undesired reaction byproducts, carbon dioxide production also correlates to product yield. While not yet completely defined, we propose to collect pollutant release data related to the risk-based factors (global warming, ozone depletion, etc.) and correlate it to various unit operations. These collections will be called Waste Inventory Factors (WIFs), and will be required input for "quick" risk assessment and environmental comparisons of processes. By correlating to unit operations, WIFs should be easily adapted to commercially-available process simulators.

WIFs and data concerning environmental regulations could be used in conjunction with commercially available chemical process simulators to judge the most optimum pollution prevention design alternatives. This information, combined with data concerning chemical plant compatibility, energy usage, and economics of operation, are necessary inputs to the process designer to estimate the environmental consequences of any design option. WIFs and regulatory data could feed any number of a risk-based tools to evaluate risks to the environment and to human health from pollutant releases at the chemical process plant. At the very least, the design engineer would be able to determine if releases from the process will comply with current and with likely future environmental regulations. If a more detailed analysis of environmental risk is desired, the engineer would be able to simulate environmental concentrations at either a local or regional scale and ultimately assess risks to special environmental compartments, to biota, and to human health. This latter scenario will allow for the most environmental benign chemical process to be used and may provide a market advantage to the chemical producer over similar products or processes which are not manufactured in the most environmentally optimum fashion.

One key area which would address the assessment function of a pollution prevention module would be a database of environmental regulations. This database would alert the process designer of potential statute violations.

Approach: This project will assemble key elements for a general WIF data resource. The approach will be 1) to compile and evaluate emission factor databases from the scientific literature on a per-unit-operation basis, 2) to develop a WIF data acquisition plan and 3) to initiate screening of commercially-available environmental regulations databases. Subsequent to this project additional data sources related to by-product formation, operation-based wastes and other non-salable wastes will need to be identified in order to create a complete WIF parameter set. Some of these may be interfaced through results of another project entitled: Chemical Industry Planning System: Phase I Prototype.

Regarding regulatory information, it is expected that while information regarding commercially available regulatory databases is easily obtained, screening and subsequent vendor negotiations can be time consuming. Accordingly, we plan to initiate this activity with a literature search and telephone contacts with database vendors. Selected screening will occur in the latter part of our first year efforts. A next step, outside the scope of this project would be to generate an integration plan based on results of the screening.

Status: While begun as a multiyear effort based on funding from USEPA National Risk Management Research Laboratory, it has subsequently been cut to a one-year effort.

J. R. Baker, P. P. Radecki, B. A. Barna, T. N. Rogers; Michigan Technological University. (References : Baker 1995a, c, d; Barna, 1994; Hertz 1995 b, c, d; Radecki 1995 b, c, d, e, f, h, j, l, m, n)

Goal: The goal of the CPAS Core Project is to bring design tools, developed in the Clean Process Advisory System Focus Area, to industry in the most useable form.

Rationale: Maintaining a central node for distribution and coordination of design tools developed under the CPAS Focus Area is the most effective way to supply them to industry. Quick distribution in a consistent fashion will provide the greatest opportunity to realize pollution prevention benefits from the collective efforts of all CPAS investigators. The CPAS Core Activities project provides a central node of staff and resources for distribution of design tools.

Approach: Specific aspects of this work include:

- Sponsoring and attending national meetings to familiarize the industrial sector with efforts within the CPAS Focus Area.

- Constructing a single program (front end) by which all CPAS design tools (including tools developed by strategic alliance partners, National Center for Manufacturing Sciences (NCMS), Center for Waste Reduction Technologies (CWRT) and other outside parties) can be accessed once installed on a personal computer. This front end should also provide a mechanism for transfer of data between CPAS tools.

- Development of a CPAS business plan and framework for product distribution.

- Release of a demonstration version of CPAS to provide information about current and future expected activities and software products.

- Software release on a single set of media (floppy disks, or CD ROM) from a single source, as opposed to requiring users to request software from each individual investigator.

Status: Achievements toward project deliverables include:

- Completion of a preliminary version of the CPAS front end to provide integrated access and data transfer among all CPAS tools.

- Operation of CPAS information booth at four national technical conferences.

- Release of the two versions of the CPAS Demonstration Version. One version available on diskette and operable from Microsoft Windows TM and, another version operating on the World Wide Web (http://cpas.mtu.edu) operable on any computer with access to the World Wide Web.

B. A. Barna, T. N. Rogers; Michigan Technological University. (References: Rogers 1995b, c; Toth 1995a, b, c)

Goals: This project is to create the evaluation and analysis module which will serve as the engine for design comparison in the CPAS project.

Rationale: Conceptual design and pollution control have traditionally been done at different stages in the development of a process. However, if the designer was given the tools to view a process's environmental impact at the very beginning of the design process, emphasis could be placed on pollution prevention and the selection of the environmentally sound alternatives. This could help eliminate total pollution output as well as reduce the costs of the end-of-the-pipe treatment which is currently done. Not only is it important to help the designer create multiple alternatives in the design process, but we must also provide the necessary tools to facilitate the rapid and effective evaluation of the alternatives.

Approach: The projects entitled, "Optimizer for Pollution Prevention, Energy, and Economics (OPPEE)" and "Pollution Prevention Process Simulator" served as the foundation for the current focus area entitled "Clean Process Advisory System (CPAS)". The project discussed here, "The Design Option Ranking Tool (DORT)" is one of the major components within the Design Comparison Tool Group of CPAS. DORT is envisioned as the analysis and comparison engine within CPAS which will help the designer to rank the multiple design alternatives using the various performance measures generated by CPAS. The component parts of the DORT project are: 1) Economic Evaluation Aide, 2) Costing Database, 3) Graphical Interface, 4) Stochastic Model, and 5) Advanced Hierarchical Procedure (AHP) Decision Making Aid.

Status: The software which handles the Costing Database is substantially complete, and a variety of cost correlations have been entered for all categories of major process equipment and some environmental equipment and processes. The different data sources for each unit or process can be compared graphically and selected to be included in new cost correlations, which are computed by the software using a variety of regression techniques. A prototype of the Economic Evaluation Aide has also been prepared. This software uses the Costing Database information to generate estimates of economic performance. Work has been initiated on graphical comparison and incremental analysis capabilities. A stochastic model has been prepared and applied to a discounted cash flow routine (NPV, IRR, etc.). The model uses a Monte Carlo approach to define the statistical uncertainty of input variables, such as purchased equipment cost, operating expenses, and capital investment. This information can be used to predict the statistical distribution of the expected economic parameter of interest such as NPV. Confidence intervals can then be as sociated with the economic performance indicators. A Visual Basic program, known as the Stochastic Analysis Module (SAM) has been started. SAM will compute the confidence intervals associated with the scenarios evaluated by the Design Option Ranking Tool (DORT). An Advanced Hierarchical Procedure (AHP) decision making aide has been programmed in Quick-Basic. This model picks the optimum of up to five processes based on indices provided in three "level one" areas (economics, safety, and pollution were assumed). The user is required to supply the values for the "level two" indices. AHP will rank the processes based upon this information. The model is in the process of being converted into Visual Basic for incorporation into DORT. User interface screens have been created in DORT to provide a logical place for the entry of the indices by the user.

J. C. Crittenden, D. W. Hand, T. N. Rogers, A. A. Kline, and J. Yu; Michigan Technological University.

Goals: The primary goals of this project are to develop two software modules: 1) Adsorption for Recovery (AdRecover) of organics, and 2) Multi-Component Distillation (MC-Dist). These modules are being developed for implementation in the separation technologies modeling tool group of the Clean Process Advisory System (CPAS).

Rationale: There are many liquid and vapor streams that require enrichment or recovery of organic fractions in order to be reused or recycled. Adsorption and distillation are two common technologies that may be used for this purpose. AdRecover and MC-Dist software modules will broaden the base of the separation technologies modeling tool group within CPAS. Moreover, commercial process simulators generally do not contain dynamic models for adsorption, or the latest databases for adsorbents that may be used for recovery of organics and enrichment of chemical process streams. AdRecover and MC-Dist will utilize other software modules within CPAS, including Isotherm Parameter Estimation Software (IPES; a part of the Adsorption Simulation Module) and Software to Estimate Physical Properties (StEPP). Given that the regeneration of adsorbents can generate liquid streams which need further enrichment by other technologies (e.g. membrane separations or distillation), the AdRecover activity will be closely linked to other CPAS development projects. The dynamic models and the databases included in the software will also be useful in interpreting data and selecting adsorbents in the separative reactor work within the Clean Rection Technologies Focus Area.

Approach: AdRecover will focus on removal of organic compounds from air and water streams, and their recovery using synthetic polymeric adsorbents. Recovery methods under consideration are 1) steam regeneration and organic/water separation by condensation, phase separation and/or distillation, 2) hot purge gas regeneration and organic separation by condensation and/or distillation, and 3) solvent regeneration (exsorption could be considered as the combinations of solvents and adsorbents offer a great deal of flexibility in separation approaches). The initial focus will be adsorption, followed by regeneration and organic compound recovery at an elevated temperature using saturated steam or a hot purge gas. Laboratory data is being provided by the Rohm and Haas Chemical Company (Philadelphia, PA) and Purus Corporation (San Jose, CA) to calibrate and verify AdRecover for these conditions.

MC-Dist will consider the removal and recovery of organics from highly concentrated water streams, such as steam condensate from adsorbent regeneration and in-plant streams. Separation processes to be investigated include single-stage flashing, steam stripping, absorption, and conventional fractionation.

Status: Steam regeneration data on a synthetic adsorbent has been received from Rohm and Haas for testing and verification of the steam regeneration module for AdRecover. The module itself continues in prototype development. An effort is also being made to locate additional industrial partners for the development team. There are several potential industrial partners which could be added to the team including: Dow Chemical, Barneby-Sutcliffe, Calgon, and Westvaco.

A test version of MC-Dist has been created, including the multicomponent distillation module. This version is being distributed to the Michigan Technological University senior Plant Design class for testing. Currently, MC-Dist is being linked to StEPP and the Design Option Ranking Tool (DORT). MC-Dist will serve as a test case for the pollution indices and process economics included in DORT. The steam stripping module for MC-Dist is currently in development.

D. A. Crowl, Michigan Technological University.

Goal: The goal of the research is to provide the process designer with two risk tools to evaluate the hazards associated with fires, explosions and chemical releases. This will be accomplished by implementing two existing hazard indices on an interactive PC platform: the Dow Fire and Explosion Index, and the Dow Chemical Exposure Index. These tools will be integrated into the Clean Process Advisory System (CPAS) environment.

Rationale: The Dow Fire and Explosion Index and the Dow Chemical Exposure Index are two recognized procedures for identifying the hazards in a chemical plant due to the presence of flammable and toxic materials. Currently, these procedures exist only in booklet form, requiring manual entry of data to determine the results. The indices are not available in an integrated design environment, such as CPAS. The purpose of the proposed work is to implement these procedures in an interactive, Personal Computer (PC) environment, and to integrate them into the CPAS computing environment. These indices will insure that design decisions are not made at the expense of process safety.

Approach: The approach used for this project is: 1) development of a fully functional Dow Fire and Explosion Index and Dow Chemical Exposure Index as a CPAS tool (the modules will be written in Microsoft Visual Basic, and will interface to other CPAS tools), 2) development of an interactive user environment, 3) development of a database containing information relevant to both Dow indices, 4) testing of the resulting software, and 5) certification of the results.

Status: Currently, the implementation of the Dow Fire and Explosion Index as a stand alone module is essentially complete. This includes the interactive environment, the database, and help support system. Future work will include continued testing, certification by Dow (if possible), and interfacing with CPAS. Work will begin soon on the development of the Dow Chemical Exposure Index. Work is a few months ahead of schedule.

D. A. Crowl, Michigan Technological University.

Goals: The goal of the research is to provide the process designer with a tool to evaluate the hazards associated with reactive chemistry. This tool would be integrated into the Clean Process Advisory System (CPAS) environment.

Rationale: Many chemical plant accidents are the result of reactive chemistry. This can be due to unknown reactive behavior or incompatibilities between various chemicals. The rationale behind the proposed work is to develop a screening tool for CPAS to insure that decisions are not made with respect to pollution prevention that result in a hazardous reactive chemistry situation.

Approach: The approach used for this project is: 1) evaluation of existing methods and programs for screening the reactive nature of chemicals, 2) selection of the best approach for implementation in CPAS, 3) implementation of a software module for CPAS, including an interactive user interface, an interface to existing modules, output, and development of any necessary databases, and 4) testing and certification of the results.

Status: This project was initiated this summer. Preliminary work, including acquisition of existing screening methods for evaluation has begun.

D. W. Hand, J.C. Crittenden, A. S. Mayer, J. R. Mihelcic; Michigan Technological University. (References: Hand 1995c; Hokanson 1995b; Mayer 1994; Voigt 1994a, b)

Goal: The Environmental Technologies Design Options Tools (ETDOT) are a compilation of self-contained tools for use in assessing and implementing effective treatment strategies for gaseous, aqueous, organic, and solid waste by-product streams. ETDOT will assist CPAS in evaluating the technical and economic feasibility of source reduction, versus end-of-pipe treatment and waste segregation, versus treatment at a central facility. It is envisioned that eventually ETDOT or its component parts will be integrated with process simulators, or other manufacturing design tools, to provide for more effective source reduction.

Rationale: Currently, there is much interest by the industrial and regulatory communities in quantifying air, water, and solid pollutant emissions from waste treatment facilities, and in estimating the fate and treatability of specific potential pollutants produced during the manufacturing process. The goal of both communities is to effectively reduce production of difficult and costly-to-treat pollutants, and optimize destruction of easy-to-treat pollutants in a cost effective and environmentally safe manner. Before this goal can be achieved, reliable mathematical models, which describe industrial manufacturing and pollution treatment processes, must be developed and coupled into a user-friendly modular form.

This project is aimed at developing advanced pollution treatment models, and integrating them with industrial manufacturing process simulators.

Approach: Models are being developed for metal and organic chemical fate during conventional wastewater treatment, air stripping and carbon adsorption. The software is being developed for each unit process as a stand alone package with the ultimate goal of linking them into the overall framework of CPAS. Software is being validated from plant data including different industrial sources.

Status: Tools which have neared completion during the past year include: 1) software for predicting the Fate of Volitle Organic (FaVOR) compounds in wastewater treatment facilities; 2) software for predicting the Fate of Metals (FaMe) in wastewater treatment facilities; 3) gas- and liquid-phase Adsorption Simulation software; 4) Software to Estimate Physical Properties (StEPP); and 5) Aeration System Analysis Program (ASAP) software for removal of volatile organic compounds from water by surface, bubble, and counter-current packed tower aeration techniques.

FaVOR and FaMe have been coded into user friendly software tools. Current work is focused on validation of the two models to actual plant data obtained from a variety of industries. A reliable method to estimate sorption capacity to sludge is being developed, and a database of biological degradation rates for many common pollutants is being constructed. In addition, user manuals for both models and testing by academic and industrial personnel will occur in anticipation of software release next year.

Version 1.0 of Adsorption Simulation Software was completed and alpha-tested. The few logical errors found are currently being corrected. One of the Adsorption Simulation Software's numerical simulation methods, the equilibrium column model, does not appear to be providing logical results when more than two components are used. This problem is also being corrected. The equilibrium isotherm database is presently being upgraded with more gas-phase single solute isotherm information. The Adsorption Simulation Software manual is being edited, and several examples are being added to increase user-friendliness. A Beta-test version should be available in early 1996.

Version 1.0 of StEPP has been completed and alpha tested. The manual for the software will be completed in the next few months.

Version 1.0 of ASAP is about 95 percent complete and will be finished in the next few months. The manual for the software will also be completed at that time. In the next few months, the legal issues of licensing all software will also be addressed.

R. M. Patty, J. W. Sutherland, C. R. Baillod, Michigan Technological University; D. W. Hertz, D. Grandy, the M.W. Kellogg Company. (References: Hertz 1995a, Patty 1995)

Goal: The goal of this project is to develop a CD-ROM based multimedia system for designers to infuse environmental considerations into the design process for constructed facilities, while simultaneously evaluating other facility performance criteria. This system will also serve as a resource database for manufacturers desiring to better understand field problems associated with installing their products.

Rationale: Chosing environmentally preferred options can produce beneficial effects to the entire construction or remodeling project. A well-known example of this is the use of citrus or other aqueous-based solvents to strip paint to avoid volatile organic compound (VOC) releases which are associated with chlorinated solvents. When employees are not distracted by health or safety hazards, they can be attentive to production. Modular designs, to reduce the cost of field assembly, are also likely to be safer to build. Modular considerations, beyond their initial construction, could make them easier to maintain, and hence, more reliable. This extends the life of the facility and reduces waste, which is of primary environmental concern. Further, modular prefabrication and assembly can allow large assemblies to be hoisted into place, reducing worker exposure to elevated work tasks. Included in the database are specific examples, pictures and video clips on how to successfully do these things at several facilities.

Incorporating safety and environmental issues routinely into design decisions requires improved availability of usable and applicable information for the work at hand. If information is unavailable or hard to reach, one must rely on one's own experience, plus that of others to make decisions. These other sources of advice or experience are not always available, so decisions are often made in rather isolated conditions. The new software being developed in this project is intended to fill this important void, and to improve constructability within the engineering design stages, as well as during construction operations.

Advanced ergonomic and cognitive learning research in this area by the primary investigator and others has found constructability data to be diverse and interrelated, usually containing issues relating to more than one facility performance criteria. Further, use of a large constructability information base must be intuitive, matching the natural cognitive organization of other information used in the design process. By extracting and matching this natural organization, the interface becomes intuitive and easy to use. The search process actively draws existing knowledge into the engineer's working memory, preparatory to infusing it with the new environmental criteria.

Approach: The M. W. Kellogg Company and MTU are collaborating in this co-development project. The combined effort will create an interactive multimedia information database, containing constructability examples from environmental and safety perspectives, applicable to many of the tasks performed during design and construction. Advanced ergonomics are being incorporated into this tool.

The demonstration module produced by this research will contain sufficient material to plant principles of pollution prevention and sustainable development at the forefront of constructability design tools. It will be a saleable product (on CD-ROM). A team and track record will be established, which can attract new data sources and funding to expand and update the database with environmental/safety/constructability technology appropriate for use by practicing facilities designers. Promising new or existing pollution prevention technologies, requiring additional research to enable and encourage reduction to practice, will be identified, and white-papers and proposals drafted.

Status:

a. Kellogg's VAX-Based Constructability Checklist has been translated to a PC system format
b. Rapid Prototype has been developed and made ready for demonstration
c. Current system includes: (~90 MBytes)

1. 700+ Lessons Learned - mostly low density
2. 20+ Lessons Learned - high density
3. 350+ Construction Images, digitized & hyperlinked
4. 8 Construction Process Digital Video Clips
5. M.W. Kellogg Constructability Manual, modules 1, 2 & 3

d. User Interface prototype programming is underway
e. Field data collection and database content development is ongoing
f. Technical review of lessons learned generated is underway

T. N. Rogers, A. A. Kline; Michigan Technological University. (References: Hokanson 1995a, b, c; Kindt 1994; Luehrs 1995; Penke 1994; Rogers 1995a, d, e; Schams 1994)

Goals: This project continues to be the primary physical and chemical property resource for CPAS tools. The project provides supporting consultation and data resources on an as-needed basis. Results are generally available through a stand-alone tool called the Chemical Property Tool and in various modular forms. The project also facilitates data exchange between tools. Ultimately, the goal of this ongoing support project is the creation of a general Physical Property Management System (PPMS) that will serve as an expandable framework for adding estimation algorithms and third-party generated data resources.

Rationale: Physical and chemical property measurements and estimations are central to virtually all environmental assessment and process design decisions. Despite this singular importance, expertise in physical and chemical properties tends to be a specialization beyond the capabilities of most process and product designers. By being closely aligned with the Physical Property and Thermodynamics Research Group (P2TRG) in the MTU Chemical Engineering Department, this project continues to insure that this expertise is available and becomes incorporated into CPAS tools. The P2TRG also conducts two programs dealing with chemcials of environmental interest for the Design Institute for Physical Property Data (DIPPR) of the American Institute of Chemical Engineers.

Approach: The first Chemical Property Tool modules have been designed to provide data support to the Adsorption Simulation module of ETDOT. These include Software to Estimate Physical Properties (StEPP) and Isotherm Parameter Estimation Software (IPES). StEPP is in an unique position because it may ultimately link to every other tool and module within CPAS. Many of the tool development efforts now underway (or newly proposed) depend upon a working StEPP program for their development, testing, and release. Much of the recent work on StEPP has focused on modelling equilibrium adsorption isotherms to support the Adsorption Simulation Software fixed-bed software. IPES has been a collaborative effort within CPAS to make Adsorption Simulation Software a self-contained tool which does not require the user to search elsewhere for the isotherm parameter data needed to perform simulations. StEPP performs an analogous function, supplying physical properties to Adsorption Simulation Software. These two modules are being tied together to provide estimated isotherms for any of some 1500 organic chemical adsorbates at any desired temperature, based on a Polanyi isotherm. IPES will make use of StEPP data values, such as the pure component vapor pressure (reference state for gas-phase Polanyi adsorption isotherms), and activity coefficients or Henry's constants (vapor-liquid equilibria). The infinite dilution activity coefficient, being inversely related to the solubility limit for dilute solutions, similarly provides a reference state for the liquid-phase adsorption potential. A library of Polanyi isotherms will be provided for common microporous adsorbents, primarily activated carbons and resins. Special algorithms will be included in IPES to handle humidity in gas-phase adsorption and to account for the reduction in liquid-phase adsorption capacity due to fouling by natural organic matter.

To support the AdRecover and MC-Dist module development projects, StEPP will be linked to provide vapor pressures, activity coefficients, and Henry's constants for relative volatility calculations. The Environmental Fate and Risk Assessment Tool (EFRAT) will use the StEPP chemical, physical, and environmental reactivity data in building its design option comparison indices.

Status: The project team has supported data requirements of the Adsorption Simulation Software, ASAP, AdRecover, MC-Dist and EFRAT development teams during the past budget year. Data exchange has been promoted between the various CPAS tools, allowing for significant new capabilities for creating "clean" process designs. The StEPP module of the Chemical Property Tool features a stand-alone data display and serves as a property databank for the simulation modules. StEPP has also been linked to Adsorption Simulation Software and ASAP. StEPP embodies tables of discreet data, as well as data calculation and extrapolation methods, with a broad capability that includes infinite dilution thermodynamics, polarizability estimates for carbon adsorption, isotherm prediction algorithms, and phase equilibrium algorithms. A number of pure component properties are also available in the StEPP module: vapor pressure, molar volume at the normal boiling point, liquid density, activity coefficient, Henry's law constant, aqueous solubility, octanol-water partition coefficient, soil-water partition coefficient, and partitioning onto the organic carbon portion of biomass.

A releasable Version 1.0 of StEPP is nearing completion as a physical property server for Adsorption Simulation Software and ASAP. The target release date for StEPP is near the end of 1995. A more general Physical Property Management System (PPMS) is under development using StEPP as a starting point, with a planned release date of December 1996.

There has been strong interest in both Adsorption Simulation Software and the IPES isotherm prediction program based on approximately 75 unsolicited inquiries from engineers around the country who have heard about CPAS.

D. R. Shonnard, A. S. Mayer, K. G. Paterson, M. T. Auer; Michigan Technological University. (References : Shonnard 1995a, b)

Goal: CenCITT is funding a process design software tool which will estimate environmental and health impacts of chemical process design options through a combination of emission rate estimations, screening-level fate and transport calculations, risk assessment indices, and governmental regulatory guidance. EFRAT will be a menu-based advisory system, which allows the conceptual process designer a number of options in assessing environmental and health risks. At the first level of effort, the engineer can test the process design for compliance with environmental regulations. The software will require a minimum of user-supplied data input and expertise. The risk indices will be calculated relatively quickly on a personal computer.

Rationale: Within the framework of pollution prevention, a methodology is needed for choosing the most environmentally benign chemical process or product design from a number of design options. It is highly desirable that such a methodology be scientifically based on the risks imposed to both human health, and to the environment, stemming from the operation of a chemical process or the production and use of a product. Risk evaluation to the environment should be comprehensive, including the effects of pollutant emissions on global warming potential, ozone depletion, acid rain formation, smog generation, groundwater contamination, and accumulation of pollutants in all environmental compartments, including plants and animals. EFRAT will provide the process design engineer with the required environmental impact information, so that environmental and economic factors may be considered simultaneously. Inherent in the software is the ability to incorporate toxicological properties of the pollutants released from the process. Therefore, EFRAT will focus on steps to reduce not only the total amount of pollution, but also its toxicity.

Approach: The approach taken in this project is to develop a user-friendly software package that requires minimal user input. The software will be based on a tiered framework that allows the user to conduct, either simple analyses with minimal input, or more involved analyses with detailed parameter and data inputs. The software will consist of a graphical user interface (GUI), an environmental risk index calculator (ERIC), and a multi-media fate and transport model (MMFAT). ERIC will generate indices that describe the relative risk of a chemical release to the environment. The risk indices will allow comparison between several design options, by incorporating compound-specific, process emission estimates. The user will enter the compound name(s) and the rate of release of the compound. Relative risk indices will be produced from a combination of physical, chemical, and biological characteristics of the compounds, including ecological or human health toxicology characteristics, and an estimation of environmental persistence. At least one risk index will be generated for each compartment. The risk indices will be based on comparison of the risk of the compound in question to selected benchmark compounds. Examples of benchmark compounds would be CO2 for global warming impacts, CFC-11 for stratospheric ozone depletion impacts, and benzene for human health risks from ingestion of contaminated water. Fate and transport modeling will be required to supply some of the numerical values needed to calculate the risk indices, (e.g. residence times, persistence, or masses in environmental compartments). The MMFAT portion of the software will provide these quantities. MMFAT will rely on individual fate and transport calculations for each environmental compartment to determine compound masses in each phase (e.g. particulate, aqueous or biotic phases), as a function of time. The fate and transport model will incorporate chemical transport and degradation mechanisms within and between environmental compartments. The separate compartment processes will be integrated into a single model that is both accurate and efficient computationally.

Status: Developing the GUI is currently underway as graduate students become familiar with programming using Visual Basic. Sources of data required for calculating risk indices within ERIC are being identified and organized. This data includes environmental partitioning parameters (from StEPP), and toxicological data (from Concurrent Technologies Corporation). A conceptual framework for estimating environmental persistence has been identified for MMFAT based on a multimedia compartment model (MCM) approach. A number of candidate models and software were recently evaluated for use in MMFAT before choosing the MCM approach. A critical evaluation of EPA unit-specific emission factor databases and commercial emission estimation software has been completed. Plans for incorporating the most accurate emission factors are being made. Plans are also being made for locating electronic databases of environmental regulations.

K. Wilson and N. Kim, Michigan Technological University.

Goals: Pollution prevention through in-process waste minimization is being evaluated in order to determine better reactor operating schemes for the polydimethyl siloxane (PDMS) polymerization reaction pilot plant in the MTU Department of Chemical Engineering Process Simulation and Control Center. Mixing and kinetic studies to maximize the yield of the desired product (PDMS) will be carried out using an approach similar to HAZOP analysis, but focussed instead on pollution prevention. Improved reactor operating schemes will be simulated by mathematical modeling. Material and energy balances are to be attempted, in large measure, to identify and quantify losses of gas and liquid in the plant. The ultimate goal is to optimize pilot-plant operating conditions.

Rationale: This project serves as a test case which will hopefully lead to a method for evaluating many plants for in-process waste minimization. Test cases provide a rapid means to evaluate proposed schemes and avoid conducting lengthy development of theoretical approaches which are impractical for plant application. They are the basis from which powerful "generic" approaches can be built.

Approach: Our approach is to evaluate different PDMS reactor control schemes on a bench-scale system which will then be mathematically modeled, tested on the pilot scale, and eventually scaled up to an industrial size process. Mass balance determination and process control will be improved through installation and use of improved measuring devices in the pilot reactor.

Status: The pilot-scale batch reactor for PDMS production is already on-line at Michigan Tech University with some operating experience. In order to develop a better understanding of the polymerization chemistry, a bench-scale batch reactor system was designed which would test the reaction under strict control. Several tests have been performed and using these results a new approach to the pilot plant contol has been developed for early FY1996. As is typical for process control research, much of the activities over the past year have involved equipment installation and evaluation.

Temperature is a major controlling factor in the PDMS polymerization reaction. A new control scheme was developed which would provide control temperature within 1-2 degrees C. This kind of control has not been obtained on any bench-scale experiments previously performed. The new method involves a viscometer being installed in a liquid recycle loop. The piston-style apparatus measures viscosity based on the amount of time it takes a piston to complete a cycle. The chamber is surrounded by a jacket containing the process fluid to insure the viscometer is operating at a known temperature, the recycle loop temperature, and to provide a location (in the jacket) at which this temperature can be measured. Viscosity within the reactor is then correlated by knowing the recycle loop viscosity and temperature and the reactor temperature measured through a thermocouple in the reactor. Once the viscosity remains constant for 60 minutes, the polymerization is complete and the low boilers are removed. Testing with the new equipment has not detected any fluid loss during plant operation.

Another aspect in the reaction involves removal of low boilers. This is accomplished by raising the temperature to 160 degrees C and placing the system under a vacuum. The system remains closed during the removal. Since KOH is used as a catalyst in the reaction, it must be neutralized prior to removal of low boilers. By bubbling CO2 through the system for 5-7 minutes, the catalyst is neutralized and is not an issue during low boiler extraction.

The first objective was to show repeatability in the system. A target viscosity of 200 cp was selected and a batch recipe was developed which should obtain this viscosity. The system was ran at the specified recipe with all operating parameters kept constant. Nothing was varied in the system.

The target viscosity was attained in only one run. There are many possible explanations for this and future experimentation is being designed in order to explain these results.

According to material balance calculations, the system is losing approximately 15% of the reactants. This could be the cause of the lower than expected viscosities. One explanation is that the nitrogen, which is continuously purging the system, could be carrying out a volatile component with it when it exits the condenser. If this component is the monomer-containing feed fluid, that would mean that there is not enough monomer to make the desired polymer. In order to determine if this is the case a cold trap is going to be placed around the condenser in order to trap anything leaving the system except the nitrogen. The first thing that will be used is dry ice. A dewars condenser will be used which will hold the dry ice. If dry ice doesn't prove to be cold enough to trap the volatile component, the condenser can hold liquid nitrogen. If an appreciable amount of substance freezes on the walls of the condenser, the condenser will be rinsed with heptane in order to perform a gas chromatograph which will tell the make-up of the residuals.

Another reason for the lower viscosity could be poor mixing. In order to test this hypothesis, a Morton type flask and a different magnetic stirrer have been ordered. The Morton type flask has 4 baffles built in which will aid in complete mixing of the system. The stirrer will rest on the bottom of the round bottom flask reactor, with baffles on top. This combination will provide complete and thorough mixing in the system.

As the bench-scale apparatus installation and equipment evaluation nears completion, the stage is set for waste minimizing control schemes to be experimentally evaluated and mathematically modeled. This activity will form the bulk of future activities on the project.

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