Question

1 kmol/h of a feed stream containing 15, 45 and 40 mol% of nitrogen, n-butane and n-pentane at 500 ºC and an unknown pressure, is cooled isobarically to a temperature of 105 ºC and fed into a flash drum operating at the same temperature (105 ºC) and pressure. If the vapor fraction V/F in the drum is equal to 0.5, determine the pressure at which the flash drum operates, and the flow rates and composition of both streams leaving the drum. Suggestion: to find the range of possible pressures, first determine the bubble and dew pressures of the mixture at 105 ºC. Here you would need to submit (1) an Aspen Plus Document file (i.e., GroupXX_Problem2.apw) with your final solution, and (2) a short file/write-up explaining how you solved this problem.

Answer 1

STEP 1 : DETERMINING THE COMPONENTS

SELECT METHOD OF SOLVATION

GO TO SIMULATION ENVIRONMENT SELECT HEATER AND FLASH COLUMN AND CONNECT THE STREAMS

SPECIFY INPUT STREAM FLOW RATE, TEMPERATURE AND PRESSURE

SPEICIFY HEATER INPUT TEMPERATURE AND PRESSURE

SPECIFY FALSH COLUMN INPUT PRESSURE AND TEMPERATURE

RUN THE PROGRAM

NOW SET UP A DESIGNSPECS TO CLACULATE THE PRESSURE TO OBTAIN VF=0.5

DEFINE THE VARIABLE TO BE ACHIEVED THAT IS THE VAPOR FLOW RATE TO BE SET TO TARGET OF 0.5 KMOL/HR

NEXT IS TO SPECIFY THE VARIABLE TO BE VARIED IN ORDER TO ACHIEVE THE RESULT THAT IS THE FLASH COLUMN PRESSURE

CHECK THE RESULT OF THE DESIGN SPECS FOR THE REQUIRED PRESSURE OF THE FLASH COLUMN TO BE OPERATED AT 105 C IS OBTAINED AS 32 BAR