Calculation of Reaction Heat in “Daily Discussion” – [1. Reaction Engineering and Reactors] (2017.08.04)

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This post was last edited by *amingteda on 2017-8-15 at 22:35. To improve everyone’s ability to use AspenOne for analyzing and solving problems in chemical processes, the “One Discussion per Day” series has been introduced for learning and discussion. Later, questions will be raised centered around various themes for academic discussion. I hope everyone will engage in active discussions to improve together! The initial topics are set as: 1. Reaction engineering and reactors ； 2. Distillation, extraction, absorption processes and columns ； 3. Heat transfer process and heat exchanger ； 4. Process optimization, design, and control ； 5. Heat exchange network integration and optimization ； 6. Economic evaluation of engineering technology. As is well known, chemical reaction processes are at the core of the chemical industry, and the calculation of the heat effects of reactions is crucial for chemical process design. So, which reactor module in Aspen Plus should be used to calculate the reaction heat, and how should it be configured to achieve this? What is the difference between the calculated reaction heat release and the actual conditions in engineering practice? Can it be used in engineering design? Dear sea friends, please actively participate in the discussions – there will be financial rewards for that. The reference discussion will be published within a week; the answers are for reference only. ——Jack Xia －－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ Answer key: I. Calculation of reaction heat: 1. Select Rstoic ； 2. Enter the reaction equation in Blocks/Reactions ； 3. For Blocks/Heat of Reactions, select Calculate heat of reaction, enter the reaction number, as well as the reference temperature, pressure, and phase state ； 4. Run the calculation. II. Differences between the reaction heat release and engineering practice: For the reactions I have encountered so far, such as methanol synthesis (–90.2 kJ/mol CO converted, under standard conditions), Fischer-Tropsch synthesis (apparent value of –140 to –170 kJ/CO converted, under standard conditions), and methane synthesis (–206 kJ/mol CO, under standard conditions), I used the V7.1 database, and in all cases I obtained reaction heat values that were consistent with the thermodynamic data. The heat released in the reaction can be determined by multiplying the reaction heat by the amount of reactants used, or it can also be obtained directly using the heat load value calculated from A+’s Rstoic (provided that the feed temperature is set to match the reaction temperature, and that all relevant reaction feeds and conversion rates are entered accurately). Based on my current experience, the heat release amount from synthetic reactions, as calculated using the A+ value, is almost equivalent to the heat transfer value corresponding to the steam production during industrial pilot operations; this actually confirms that the A+ calculation value can be used in engineering design. The premise here is that the raw materials and products involved are commonly used, and the database is relatively complete in A+. It should be noted that when unfamiliar with the compounds involved in a reaction system, thermal data should be consulted carefully and compared with the data from simulation software to verify their reliability and accuracy.