Skip to main content
Engineering LibreTexts

7.39: Untitled Page 184

  • Page ID
    18317
  • Chapter 7

    dioxide in the synthesis gas must be removed before the gas is used as feed for an ammonia converter. This process is illustrated in Figure 7.16, and the product gas in Stream #3 is required to contain hydrogen and nitrogen in a 3

    to 1 molar

    ratio. In this problem you are asked to determine the ratio of e th molar flow rate

    of the flue gas to the molar flow rate of the water gas, i.e., M

    / M , that is

    1

    2

    required in order to meet the specification that ( y

    )  3( y

    ) .

    H2 3

    N2 3

    Answer: M

    / M  0 . 467

    1

    2

    Figure 7.16. Synthesis gas reactor

    7‐17. A process yields 10,000 ft3 per day of a mixture of hydrogen chloride ( HCl ) and air. The volume fraction of hydrogen chloride ( HCl ) is 0.062, the temperature of the mixture is 550°F, and the total pressure is represented by 29.2

    inches of mercury. Calculate the mass of limestone per day required to neutralize the hydrogen chloride ( HCl ) if the mass fraction of calcium carbonate ( CaCO ) in the limestone is 0.92. Determine the cubic feet of as g liberated

    r

    pe

    3

    day at 70°

    F if the partial pressure of carbon dioxide ( CO )

    is 1.8 inches of

    2

    index-354_1.png

    index-354_2.png

    Material Balances for Complex Systems

    345

    ercury.

    m

    Assume that the reaction between HCl and CaCO to form CaCl , 3

    2

    CO , H O goes to completion.

    2

    2

    7‐18. Carbon is burned with air with all the

    carbon being oxidized to CO

    .

    2

    Calculate the flue gas composition when the

    percent of excess air is 0, 50, and

    100. The percent

    of excess air is defined as:

     molar flow 

    mol

    ar t

    ra e of

    rate of oxygen

     consump

    tion of oxygen 

    percent of

    entering

    owin

    g to reaction

     

     100

    excess air 

     molar rate of

    consumption of oxygen

     owing to reaction 

    Take the composition of air to be 79% nitrogen and 21% oxygen. Assume that no NOX is formed.

    7‐19. A waste gas from a petrochemical plant contains 5% HCN with the remainder being nitrogen. The waste gas is burned in a furnace with ess

    exc

    air

    to make sure the HCN is completely removed. The

    combustion process

    is

    illustrated

    in Figure 7.19. Assume that the percen

    t excess air is 100%

    and

    Figure 7.19. Combustion of hydr

    ogen cyanide

    index-355_1.png

    index-355_2.png

    346