Process Description
The SPM-2100 Continuous Stirred Tank Reactor (CSTR) Process Simulation can be configured to react any two gases. The reaction can be exothermic or endothermic. The default configuration reacts ethylene (reactant A) with benzene (reactant B), an exothermic reaction, to produce ethylbenzene (product C), an intermediate chemical used in the manufacture of styrene monomer. There are no side or competing reactions simulated.
Reactants A and B are fed to the Continuous Stirred Tank Reactor (CSTR) where they are completely mixed with a motorized agitator.
Reactant A feedstock is assumed to come from a typical refinery FCC. Consequently, there is a substantial concentration of inerts in the feed. Since the reaction is highly exothermic, the inerts serve to dilute the feed and aid in preventing a reactor run-away.
Reactant B feedstock is assumed to be of the highest available industrial grade and is therefore effectively 100% pure for the purposes of this simulation.
The reactor is sized to convert most of reactant A to product. The feed molar ratio of reactant B to reactant A is maintained at 3.25 to 1.
The product
stream is purified downstream of the reactor through a series of distillation
columns. The inerts are vented, recompressed, and used as a fuel gas elsewhere
in the plant. Reactant B is recovered, purified, and recycled back to
the reactor. The purification of the product stream is outside the scope
of this simulation.
It is desired to manufacture approximately 86.59 KPPH of product C. 124.83 KPPH of 23.92 WT% reactant A is reacted with 270.21 KPPH of 100.00 WT% reactant B. 395.05 KPPH of 21.92 WT% product C leaves the reactor at 800.0 Deg F and 280.0 PSIG.
Reactant A feed is supplied at 350 Deg F and reactant B feed is supplied at 950 Deg F. The reactor is heated by the reactor jacket until the reaction strikes and is self-sustaining. Once this occurs the reactor jacket cools the reactor to maintain a temperature of 800 Deg F. The reactants are supplied from storage to the reactor at 500 PSIG and the product is discharged from the reactor to storage at 0 PSIG.
The reactor is a cylindrical vessel with a total volume of approximately
15904 cubic feet.
Under design conditions, the reactor is operating at close to 100% of its capacity to convert reactants to product.
Both reactant feed valves and the reactor outlet product valve are designed with twice the capacity of the design flow rate for the reactor.
The reactor jacket has been designed with sufficient capacity to heat or cool twice the design reactor feed flow rate.
The reactant A feed flow loop is outfitted with a composition analyzer
(AI-201) that measures weight percent A, the balance being inerts. The
supply temperature and pressure are indicated by TI-201 and PI-201 respectively.
The feed block valve can be opened and closed with switch HV-201. Reactant
A flow to the reactor is modulated by flow controller FIC-211.
The reactant B feed flow loop is outfitted with a composition analyzer (AI-202) that measures weight percent B, the balance being inerts. The supply temperature and pressure are indicated by TI-202 and PI-202 respectively. The feed block valve can be opened and closed with switch HV-202. Reactant B flow to the reactor is modulated by flow controller FIC-212.
The reactor contents are mixed by a motorized agitator which can be turned on and off with switch HS-223 and whose speed can be controlled with SIC-223.
Reactor temperature is indicated by TIC-223 which controls the reactor temperature by modulating the cooling and heating flows to the reactor jacket, indicated by FI-204 and FI-205 respectively. Total flow through the reactor jacket is indicated by FI-206. Cooling flow inlet temperature is indicated by TI-204, heating flow inlet temperature is indicated by TI-205, and reactor jacket outlet flow temperature is indicated by TI-206. The cooling flow block valve can be opened close with switch HV-204, the heating flow block valve can be opened and closed with switch HV-205, and the reactor jacket effluent block valve can be opened and closed with switch HV-206.
Reactor pressure is controlled by PIC-223 which modulates the reactor effluent flow, indicated by FI-223. The reactor effluent block valve can be opened and closed with switch HV-203. Product discharge pressure is indicated by PI-203.
Reactor compositions are indicated by AI-221 (WT% A), AI-222 (WT% B), and AI-223 (WT% C). Inerts compositions can be determined by difference.
The reactor temperature controller is a "split-range" controller.
At 0% controller output, the cooling flow control valve is fully opened
and the heating flow control valve is completely closed. At 50% controller
output, both cooling and heating flow control valves are completely closed.
At 100% controller output, the heating flow control valve is fully opened
and the cooling flow control valve is completely closed.
All faults
can be failed high or low to any degree with any of 8 fault function generators
(step change, square wave, staircase, stairs, ramp, sawtooth, slope, or
sine wave). Faults can be programmed to start and/or stop at various times
during a simulation exercise.
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You may create a virtually unlimited number of scenarios and training
exercises by programming the faults described in the previous section.
You can then establish performance standards for each one of those exercises.
Simtronics provides a number of exercises with established performance
standards for each process simulation. The objective, time to complete
the exercise, cause, effect, solution, and procedure for each exercise
is documented. You may modify these procedures to more closely reflect
your particular process plant operating procedures.
- Exercise 1: Design
- Exercise 2: Cold Start
- Exercise 3: Reactant A WT% Increases to 50 WT% A
- Exercise 4: Reactant Feed Temperatures Drop