Calorimeter
|
NOTE: This feature is distributed with SysCAD but is currently in BETA. Please contact us ([email protected]) if you run into any issues using this model. This page is currently under development and details may change. Use with caution - we do not guarantee compatibility between different BETA versions. |
Navigation: Models ➔ Material Handling Models ➔ Calorimeter
General Description
This closed tank Calorimeter model is for Dynamic projects only.
The model must include both a feed stream and a vent stream. The feed stream does not need to contain any material, but it must be present and connected.
- This model simulates a closed system with a predefined volume. As the contents change, the internal pressure will vary.
- The vent stream can be used to control pressure and prevent overpressure.
- Heat can be added or removed from the unit using an EHX or via a reaction heat exchanger.
Calorimeter workflow:
The current implementation of the model disallows any feed and requires the contents to be preset. (Future implementations may allow for material addition.)
- Configure the unit with the required volume and operating conditions.
- Specify Preset compositions for vapour and solid/liquid components.
- Add reactions to define the chemistry changes over time.
- Importantly, specify the rates at which the reactions occur.
- Apply pressure control if required.
- Apply temperature control if required.
- Add further control logic, in particular a trigger for setting the actual compositions at the start of a run.
These steps are discussed further in the example below.
Model theory
Most SysCAD models are based on isobaric processes where the pressure remains fixed and energy balance is described by enthalpy which includes external work associated with changing volume. For fixed volume isochoric processes, no external work is done, so energy balance is based instead on internal energy [math]\displaystyle{ U }[/math]. For a closed system with both liquid and vapour present, the numerical values of enthalpy and internal energy are close - the difference is important primarily for pure vapour systems where the isobaric and isochoric specific heats [math]\displaystyle{ C_p }[/math] and [math]\displaystyle{ C_v }[/math] will be different, affecting the temperature change in processes for these two cases.
Diagram
Inputs and Outputs
| Label | Required Optional |
Input Output |
Number of Connections | Description | |
| Min | Max | ||||
| Feed | Required | In | 1 | 1 | Feed to the closed tank. For the current version, this is inactive and any feed will be immediately bypassed. |
| Vent | Required | Out | 1 | 1 | Vent gas from the tank when the tank volume is full. |
Model Description
This model is a fixed volume tank, which represents a bomb calorimeter used in lab testing. It may also represent a closed batch process tank where the contents are fixed (although vapour may be vented).
Data Sections
- CRB - Optional tab, only visible if the Reactions are enabled in the Content Evaluation Block.
- CEHX - Optional tab, only visible if the EnvironHX is enabled in the Content Evaluation Block.
- CVLE - Optional tab, only visible if the VLEquilibrium is enabled in the Content Evaluation Block.
- Content tab - contains data on the material in the closed tank.
- PresetV/PresetSL - Optional tabs, only visible if Slurry.UsePreset option is enabled. Allows user to define the Preset vapour and slurry compositions.
- Info tab - contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
- Links tab, contains a summary table for all the input and output streams.
- Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.
Unit Type: Calorimeter - The first tab page in the access window will have this name.
| Tag (Long/Short) | Input / Calc | Calculated Variables / Options |
|---|---|---|
| Tag | Display | This name tag may be modified with the Change Tag option. |
| Condition | Display | "OK" if no errors/warnings, otherwise lists errors/warnings. |
| ConditionCount | Display | The current number of errors/warnings. If condition is OK, returns 0. |
| GeneralDescription / GenDesc | Display | An automatically generated description for the unit. If text is entered in the 'EqpDesc' field on the Info tab (see below), this is displayed here. Otherwise, SysCAD will display the UnitType or SubClass. |
| Requirements | ||
| On | Tickbox | Toggles the Gas Tank model on / off. |
| Capacity.Volume | Input | User specified capacity volume for the closed tank. |
| Capacity.MinVapVolFrac | Input | Specify the minimum volume to be occupied by vapour. |
| Volume.Tolerance | Input | In typical operation, the pressure is adjusted so that the contents volume is equal to the specified Capacity.Volume to this tolerance. |
| PressureControl | Tickbox | Allows the user to specify a pressure control setpoint. Vapour will be released via the Vent stream if pressure is above the specified value. |
| ControlPressure / ControlP | Input | Visible when ControlPressure is on. User specified target pressure. |
| Reactions | List | Reaction Block (RB) - Enable or disable Reactions and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, RB becomes visible and may be configured. Note: The user does not have to configure a reaction file, even if this block is checked. |
| EnvironHX | List | Environmental Heat Exchanger (EHX) - Enable or disable Environmental Heat Exchange and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, EHX becomes visible and may be configured. Note: The user does not have to configure an environmental heat exchange, even if this block is checked. |
| VLEquilibrium | List | Vapour Liquid Equilibrium (VLE) - Enable or disable Vapour Liquid Equilibrium and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, VLE becomes visible and may be configured. Note: This option may automatically adjust the species make-up. |
| PresetData | ||
| Temperature / T | Calc | Preset temperature of the closed tank. |
| Pressure / P | Calc | Preset pressure of the closed tank. |
| Slurry.UsePreset | Tickbox | Adds two new tab pages: PresetV and PresetSL. These allow the user to define the initial composition for the gas phase and slurry phase, respectively. |
| SLMass | Input | The starting content slurry mass. |
| Options | ||
| ShowQVent | Tickbox | Display the vent stream data. |
| Results (Tank Contents) | ||
| Temperature / T | Calc | Temperature of the closed tank. |
| Pressure / P | Calc | Measured pressure inside the closed tank. |
| Volume / Vt | Calc | Total volume of the closed tank or occupied space, essential for capacity and fill-level calculations. During normal operation this should equal the volume of the tank. |
| VapourVol / VVt | Calc | Total vapour volume of the closed tank or occupied space. |
| SlurryVol / SLVt | Calc | Total slurry volume of the closed tank or occupied space. |
| SlurryLevel | Calc | Slurry Volume Fraction. |
| TotalMass / Mt | Calc | The total mass inside the closed tank. |
| SolidsMass / SMt | Calc | The mass of solids inside the closed tank. |
| LiquidMass / LMt | Calc | The mass of liquid inside the closed tank. |
| VapourMass / VMt | Calc | The mass of vapour inside the closed tank. |
| SlurryMass / SLMt | Calc | The mass of slurry inside the closed tank. |
| Density / Rho | Calc | Calculated density inside the closed tank. |
| VapourDensity / VRho | Calc | Calculated vapour density inside the closed tank. |
| SLDensity / SLRho | Calc | Calculated slurry density inside the closed tank. |
| Results | ||
| InitTtlMass / InitMt | Calc | Initial mass inside the closed tank, used as a baseline for change in mass over time |
| DeltaTtlMass / DeltaMt | Calc | Net change in mass over time inside the closed tank |
| MassRateOfChange / QmAcc | Calc | Rate of mass variation inside the closed tank |
| MtAcc | Calc | Accumulated mass over time, representing total throughput or usage across operational periods. |
| BypassMassFlow / BypassQm | Calc | Mass flow rate of any feed which is bypassed together with any excess slurry (when slurry volume is larger than available volume). |
| VentMassFlow / VentQm | Calc | Mass flow rate of vapours through the vent stream. |
| VapThermalMass | Calc | Thermal mass of vapour. |
| SLThermalMass | Calc | Thermal mass of solids/liquids. The relative thermal mass indicates when gas phase calculations involving [math]\displaystyle{ C_v }[/math] may be significant. |
| PressChange /dP | Calc | Pressure change for the time step. |
| CEHX.HeatFlow | Calc | Content environmental heat exchanger heat flow. |
| PV_Work / Work | Calc | Difference between enthalpy and internal energy. |
| HeatFlow | Calc | |
Adding this Model to a Project
Add to Configuration File
Sort either by DLL or Group:
| DLL: | MatHand3.dll |
→ | Units/Links | → | Material Handling: Calorimeter | |
| or | Group: | General |
→ | Units/Links | → | Material Handling: Calorimeter |
See Model Selection for more information on adding models to the configuration file.
Insert into Project Flowsheet
| Insert Unit | → | Material Handling | → | Calorimeter |
See Insert Unit for general information on inserting units.
Example: Zinc reaction with Sulphuric Acid
Zinc Zn(s) reacts with Sulphuric Acid H2SO4(aq) to form hydrogen gas and zinc sulphate.
Zn(s) + H2SO4(aq) = ZnSO4(aq) + H2(g)
Calorimeter Volume 5L Initial Contents 2kg total, with 20g solid Zn in 10% acid (90% H2O, 10% H2SO4) Remainder of calorimeter is filled with air (79% N2, 21% O2)
Specify the calorimeter volume, initial temperature/pressure, total weight of solids and liquids, and enable reactions.
Specify the initial vapour and slurry (liquid/solid) compositions in the Preset Tabs. In this example the vapour is air, the liquid is water with 10% sulphuric by weight, and the solid is Zinc metal. Some precalculation of mass/molar fractions may be needed to get the correct composition for the components.
Set up appropriate reactions and extents. This will typically be a Dynamic Rate based on laboratory testing or theoretical considerations. In practice the rate may depend on concentrations of reactants, equilibrium and other factors and would be calculated and set in a General Controller. A constant Rate here is just a first order rate equation, with the molar transfer rate proportional to the amount of reactant (Zinc) present.
Optionally, set up a General Controller for the model. The preset may be done manually, but it is better to automate this a General Controller, which will trigger the preset when the model run starts:
Sub PreStart()
["$Solver.Cmd.PresetProcess"] = 1
EndSub
The controller can also end the simulation, for example if the amount of reactant (here Zinc) falls below a user specified tolerance.
Zn_Mass_remaining = ["CAL_001.Content.M.Zn(s) (kg)"]
if Zn_Mass_remaining < Zn_FinalMass
StopSolver("All zinc solids have been dissolved.")
endif
The model can now run to completion.
