A chemical plant produces an ammonia‑rich waste gas that cannot be released as is into the environment. One method to reduce the ammonia concentration in the waste gas is to bubble the waste gas though a liquid solvent. Components of the gas that are highly soluble, like ammonia, will dissolve into the liquid phase. Water is an appropriate liquid solvent for this process. The chemical plant produces 125.0 m3/h125.0 m3/h of waste gas (????=0.0407 mol/L)(rho=0.0407 mol/L) initially having a mole fraction of 0.200 NH30.200 NH3 and wishes to remove 90.0% of the initial amount of NH3.NH3. The maximum concentration of ammonia in water at this temperature is 0.4500 mol NH3/mol water.0.4500 mol NH3/mol water. Neglect the absorption of other waste gas components into the water and the evaporation of water into the waste gas stream. At what rate is NH3NH3 being removed from the feed gas? rate of NH3NH3 removal: mol/hmol/h What is the minimum flow rate of water (????=0.990 g/mL)(rho=0.990 g/mL) required to scrub out 90.0% of the incoming NH3?NH3? minimum flow rate of water: L/hL/h What is the mole fraction of NH3NH3 in the scrubbed waste gas stream? mole fraction: mol NH3mol waste gas

Respuesta :

Answer:

Follows are the solution to this question:

Explanation:

In first point:

Ammonia volumetric flow =   [tex]{105} \frac{m3}{h} = \frac{7}{240} \ \frac{m^3}{ s}[/tex]

Waste gas mole density, dw[tex]= 0.0407 \ \frac{mol}{L} = {40.7} \ \frac{mol}{m^3}[/tex]

Original ammonia mole proportion in receiving waste gas [tex]= 0.120[/tex]

Mole density for ammonia [tex]= 0.120 \times 40.7[/tex]

                                            [tex]= 4.884 \ \ \frac{ \ mol}{ m^3 \text {of its incoming waste}}[/tex]

Therefore, ammonia rate is extracted from its incoming stream

[tex]= NH_3 \text{molecule density} \times \text {Volume flow rate} \\\\ = 4.884\times (\frac{7}{240})\\\\ = 0.14245 \ \ NH_3 \ \ \text{moles per second}[/tex]

As 90 percent ammonia is removed, that ammonia removal rate:

[tex]= 0.9 \times 0.14245 \\\\ = 0.128 \ \ NH_3 \ \text{moles per second} \\\\ = 460.8 \ \ \frac{mol}{h}[/tex]  

In second point:

Ammonia possessing water content [tex]= 0.35\ \ \frac{NH_3}{mole}[/tex]  

Consequently, to maintain 0.128 mol ammonia:

water moles necessary [tex]= \frac{1}{0.35} \times 0.128[/tex]

                                       [tex]= 0.365 \ mol \ water[/tex]

Water atomic weight=[tex]18 g[/tex]

Therefore, mass needed of water [tex]= 18 \times 0.365[/tex]

                                                         [tex]= 6.57 \ g[/tex]  

In this required water range of competencies stream rate:

[tex]= \frac{\text{necessary weight}}{\text{water density}} = \frac{6.57}{0.99} \\\\ = 6.63 \frac{ml}{second} \\\\ = 6.63 \times 10^6 \times 3600 \\\\ = 0.023868 \frac{m^3}{h} \\\\ = 23.868 \frac{L}{h}[/tex]

In third point:

fresh ammonia mol fraction [tex]= \frac{ \text{moles of ammonia from of the outgoing stream} }{\text{maximum moles}}[/tex]

Amino ammonia moles = 10 per cent of the ammonia moles inside an incoming stream = 0.10×initial concentration of the mole:

[tex]= 0.1 \times 4.884\\\\ = 0.484 \ moles[/tex] in an outgoing stream.  

Its total outflow moles = the total ammonia moles at the original ammonia:

[tex]\text{stream moles} = 40.7- (90\% \times 4.884)[/tex]

                     [tex]= 36.3[/tex]

So new ammonina mole fraction:

[tex]= \frac{0.4884}{36.3} \\\\ = 0.01345[/tex]