Process Flowsheet: Mixer → Heater → CSTR
A simple process combining multiple unit operations into a flowsheet:
- Mixer — blends a fresh feed stream with a recycle-like second stream
- Heater — brings the mixed stream to reactor inlet temperature
- CSTR — exothermic first-order reaction A → products with cooling jacket
This demonstrates how PathSim-Chem blocks compose into multi-unit simulations, inspired by the reactor front-end of MiniSim's Cumene Process.
System Setup
Fresh feed: 0.05 m³/s at 300 K with 2.0 mol/m³ reactant A
Second stream: 0.05 m³/s at 310 K (simulating a warm recycle)
Heater: 200 kW duty to preheat the mixed stream
CSTR: 1 m³ reactor, first-order Arrhenius kinetics, cooled by a 290 K jacket
Wiring the Flowsheet
Feed 1 (F₁, T₁) ─┐
├─ Mixer ─── Heater ─── CSTR ─── Products
Feed 2 (F₂, T₂) ─┘ ↑ ↑ ↑
│ Q T_coolant
Note: The CSTR's internal flow rate F is set at construction. Here the mixer's output flow
is used for monitoring, while the CSTR uses its own F=0.1 parameter for residence time.
18:18:23 - INFO - LOGGING (log: True) 18:18:23 - INFO - BLOCKS (total: 13, dynamic: 1, static: 12, eventful: 0) 18:18:23 - INFO - GRAPH (nodes: 13, edges: 16, alg. depth: 3, loop depth: 0, runtime: 0.264ms) 18:18:23 - INFO - STARTING -> TRANSIENT (Duration: 100.00s) 18:18:23 - INFO - -------------------- 1% | 0.0s<0.3s | 3647.6 it/s 18:18:23 - INFO - ####---------------- 20% | 0.1s<0.2s | 4489.2 it/s 18:18:23 - INFO - ########------------ 40% | 0.1s<0.1s | 4629.9 it/s 18:18:23 - INFO - ############-------- 60% | 0.2s<0.1s | 4859.9 it/s 18:18:23 - INFO - ################---- 80% | 0.2s<0.0s | 4233.5 it/s 18:18:23 - INFO - #################### 100% | 0.3s<--:-- | 3668.9 it/s 18:18:23 - INFO - FINISHED -> TRANSIENT (total steps: 1001, successful: 1001, runtime: 276.07 ms)
Results: Temperature Profile Through the Plant
Track the temperature at each stage: after mixing, after heating, and inside the reactor.
Steady-State Summary
Process Steady State ============================================= Unit Flow [m³/s] T [K] --------------------------------------------- Fresh feed 0.05 300.0 Second stream 0.05 310.0 Mixer outlet 0.1000 305.00 Heater outlet 0.1000 305.48 CSTR outlet — 305.46 Reactor C_A = 1.9452 mol/m³ (feed = 2.0 mol/m³) Conversion = 2.7%
The mixer blends both feeds to an intermediate temperature (~305 K). The heater raises it further. The CSTR then reaches a steady state where the exothermic reaction heat is balanced by cooling jacket removal, and the conversion depends on the residence time and Arrhenius rate.