HYSYS Simulation

The major units of the Aspen-HYSYS simulation for natural gas steam reforming based fuel cell system are presented in Figure 3. 

In the HYSYS simulation, the flooded condenser is simulated as a cooler with a temperature control loop manipulating cooling water rate. The reactor inlet pressure is set by the exit of the liquid recycle pump on the purge column distillate stream. 

Developed a model using a Hysis Simulation package. 

As shown in Figure 4.C.2, Aspen HYSYS simulation file is opened first. In VBA, Dim statement is used for declaration of variables, whereas Set statement is used for creating new objects. Then, values of feed flow rate, length and diameter of each reactor, and temperatures of inlet streams of both separators are transferred from cells C3 to Cll in Excel worksheet named DV to Aspen HYSYS , to Aspen HYSYS. To reduce computational time, remember to deactivate HYSYS solver before this transfer, and then activate it after transferring values of all decision variables to proceed with the calculations... 

The Excel file with the created macro and HYSYS simulation file should be placed in the same directory/folder. In Excel, the control button can be used to run the simulation for this, create a control button by going through Excel - Developer- Insert- Eorm Control, and then assign the new macro (that is, Ammonia Synthesis) to the control button by a right click on it... 

Figure 4.C3 Convergence check for recycle loop (RCY-1) and distillation column (COL-I) present in an Aspen HYSYS simulation file.

For oil, gas and petrochemical applications, the Peng-Robinson EOS (PR) is generally the recommended property package. For more details, please refer Aspen HYSYS Simulation Basis Manual. 

If desired, you can save the Fluid Package with the attached reaction sets. This will allow you to reopen this FP in any number of HYSYS simulations. 

Keywords Ammonia Process, HYSYS Simulation, CO2 emissions, Carbon Footprint... 

Footprint of such an important process in Carbon equivalent quantities is of high interest these days as immediate mitigation measures should take place in order to optimize current technologies used aiming to assure environmental sustainability of the process. Direct emissions of Carbon Dioxide from the process and its major utility sections (furnace, turbines, steam heaters and boilers) are targeted in this case study. In order to provide a good estimate of Carbon Footprint of Ammonia process HYSYS simulation software and MS Excel can be integrated to calculate process Carbon emissions. 

HYSYS simulation software was used as a tool to complete the simulation of the process (sample is shown in Fig.l). Fluid packages used in the simulation were Amines package which was used for Acid Gas Sweetening and CO2 Removal units, and Peng Robinson which was used for the rest of the units. When simulation was finalized, the following were collected ... 

Fig.l Sample HYSYS Simulation - Acid Gas Sweetening Unit/Regenerator... 

Although Ammonia production process is claimed to be clean compared to other processes, the estimated Carbon Footprint of Ammonia process considering process emissions and major utility emissions range between 785 and 999 kg C02/ton Ammonia depending on production rate, type of feedstock, and steam utilization. The use of HYSYS simulation tool with MS Excel was very useful to estimate these values. Further improvements on the simulation especially for CO2 Removal unit are required to get more accurate results consistent with desired CO2 recovery. These improvements can help in proposing new modifications on the process to reduce energy consumption and hence CO2 emissions. 

Oi, L. Aspen HYSYS Simulation of CO2 Removal by Amine Absorption from a Gas Based Power Plant, Proceedings of SIMS2007 Conference, The 48 Scandinavian Conference on Simulation and Modeling, pp. 73 - 81, Goteborg, October 2007. 

HYSYS offers another advantage for us for simulating the reactor system. It skips the steps of arranging the system of equations and reducing the work of collecting physicochemical data required to simulate a reaction system. In a HYSYS simulation, we can just pick the reactor module we want to simulate, either kinetic, conversion, or equilibrium... 

Selected screen captures from the Aspen HYSYS simulation of the Selexol-based process, (a) Selecting the DBR amines package (b) Temporary specifications for the loaded solvent stream (c) Working around problems with convergence issues with flash drum specifications (d) The final converged flowsheet. 

The work presents a simulation study of a reactive distillation (RD) unit for tert-amyl-methy 1-ether synthesis using HYSYS simulation environment. 

In this paper, we focused on the relevance of the commercial software HYSYS for the simulation of catalytic distillation columns. As in the current version of HYSYS the built-in RD module is not directly suitable for the simulation of the heterogeneous catalytic distillation process, this study is concentrated to develop a model for heterogeneous RD and to implement it in the HYSYS simulation environment. The objectives of this work are to develop a suitable simulation module for heterogeneous reactive distillation compatible with HYSYS and to apply it to an intermediary scale pilot plant unit. 

In Hysys, the pipe segment in the object palette offers three calculation modes pressure drop, flow rate, and pipe length. The appropriate mode will automatically be selected depending on the information supplied. The Hysys simulation of fluid flowing in a pipe is simulated as follows ... 

Expected catalyst weight obtained from HYSYS simulation V= 163 m )... 

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