A mathematical model for the crosslinking copolymerization of a vinyl and divinyl monomer was developed and applied to the case of methyl methacrylate and ethylene glycol dimethacrylate batch polymerization. Model results compare favorably to the experimental findings of Li and Hamielec23 for the system investigated. The model presented utilizes the numerical fractionation technique15 and is capable of predicting a broad range of distributional properties both for pre‐ and post‐gel operating conditions as well as polymer properties that were not experimentally determined from the experimental findings of Li and Hamielec, such as crosslink density and branching frequency. The effects of divinyl monomer fraction and chain transfer agent level on the polymer properties and the dynamics of gelation were also investigated.magnified image
Thermodynamic analysis of tri-reforming reactions to produce synthesis gas has been conducted by total Gibbs energy minimization to understand the effects of process variables, such as temperature (200−1000 °C), pressure (1−20 atm), and inlet O 2 /CH 4 (0−1.0), H 2 O/CH 4 (0−3.0), and CO 2 /CH 4 (0−3.0) mole ratios on the product distribution. The results reveal that high temperature and low pressure are favorable to achieve high H 2 production and CO 2 conversion. In addition, excessive additions of H 2 O, O 2 , and CO 2 bring about lower H 2 yield and CO 2 conversion, while low concentrations of H 2 O, O 2 , and CO 2 result in more intense carbon formation. To attain the maximum H 2 yield and high CO 2 conversion coupled with a desired synthesis gas (H 2 /CO) ratio for the downstream methanol production and effective elimination of carbon formation, the corresponding optimum feed ratio in tri-reforming process is identified to be CH 4 /CO 2 /H 2 O/O 2 = 1:0.291:0.576:0.088.
Flaring is crucial to chemical plant safety. However, excessive flaring, especially the intensive flaring during the chemical plant start-up operation, emits huge amounts of volatile organic compounds (VOCs) and highly reactive VOCs, which meanwhile results in tremendous industrial material and energy loss. Thus, the flare emission should be minimized if at all possible. This paper presents a general methodology on flare minimization for chemical plant start-up operations via plantwide dynamic simulation. The methodology starts with setup and validation of plantwide steady-state and dynamic simulation models. The validated dynamic model is then systematically transformed to the initial state of start-up and thereafter virtually run to check the plant start-up procedures. Any infeasible or risky scenarios will be fed back to plant engineers for operation improvement. The plantwide dynamic simulation provides an insight into process dynamic behaviors, which is crucial for the plant to minimize the flaring while maintaining operational feasibility and safety. The efficacy of the developed methodology has been demonstrated by a real start-up test.
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