Example - 05 PHREEQC Evaporation Projects

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Navigation: User Guide ➔ Example Projects ➔ 05 PHREEQC

LiOH Evaporation Examples

PHREEQC LiOHEvap1.pngPHREEQC LiOHEvap2.png

Available from Build 139.37077.

Project Location

..\SysCADXXX\Examples\05 PHREEQC\PHREEQCFull\LiOH_Evap_Calc_HX_Area.spf

Features Demonstrated

  1. The use of PHREEQCModelCfg
  2. The use of PHREEQCEvaporator
  3. The use of Compressor
  4. The use of Desuperheater

Brief Project Description

  1. Demonstrates two methods for precipitation of LiOH.H2O: multistage evaporation and mechanical vapour recompression (MVR).
  2. Supports system design by allowing users to specify target operating conditions and equipment specifications; the model then calculates key design parameters such as heat exchanger area, recirculation rates, steam requirements, and cooling water demand.
  3. Enables direct comparison between MVR and multistage evaporation configurations.

Project Configuration

Species Database

  1. The species database used for these projects contains additional information compared with standard PHREEQC projects. Several aqueous species have been defined with heat of dilution data.

PHREEQCModelCfg

  1. A modified Pitzer database is used by these projects - SysCAD Pitzer Lithium.dat. See database file for full data references for added species.

Flowsheet configuration

  1. Evaporator pressure is specified by the user.
  2. The target solids fraction in the final evaporator (precipitation of LiOH·H₂O) is achieved through steam addition.
  3. The evaporator is configured to use an embedded heater. Heater area and recirculation flow rate are calculated to satisfy the required heater temperature rise.
  4. Boiling point elevation for each of the evaporators is calculated using PHREEQC water activity prediction, i.e.:
    • [math]\displaystyle{ BPE = Tsat(\frac{P}{a_w}) - Tsat(P) }[/math]
    • Note: this is only valid if water is the ONLY volatile species in the brine
    • BPE is crucial for HX design, as it determines the correct LMTD across the HX
  5. Desuperheaters are used to remove superheat.
  6. User‑specified utility usage ratios are applied to accommodate flow‑rate variation within the project, adjusting the PID controller output maximum based on feed rate.


NaCl Evaporation Examples

PHREEQC NaClEvap1.png PHREEQC NaClEvap2.png.

Available from Build 139.37077.

Project Location

..\SysCADXXX\Examples\05 PHREEQC\PHREEQCFull_Evap\NaCl_Evap_Calc_HX_Area.spf

Features Demonstrated

  1. The use of PHREEQCModelCfg
  2. The use of PHREEQCEvaporator
  3. The use of Compressor
  4. The use of Desuperheater

Brief Project Description

  1. Demonstrates two methods for selective NaCl removal from lithium‑bearing potash brine: multistage evaporation and mechanical vapour recompression (MVR).
  2. Supports system design by allowing users to specify target operating conditions and equipment specifications; the model then calculates key design parameters such as heat exchanger area, recirculation rates, steam requirements, and cooling water demand.
  3. Enables direct comparison between MVR and multistage evaporation configurations.

Project Configuration

The configuration of this project is very similar to that used in the LiOH Evaporation Examples, with the main difference being the selected control variable. The objective of this project is to maximize the removal of NaCl and increase the concentration of lithium in the liquor. NaCl is the primary contaminant in common lithium brines.

The control target selected for this project is the KCl(s) saturation factor, set such that the removal of NaCl is maximized without precipitating KCl.

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