How much air is needed for the secondary reformer

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Reference no: EM131297143

Chemical Process Project Descriptions - Plant for Production of Ammonia: Haber - Bosch process

Material Balance Questions: Let G = 100 mol/s unless stated otherwise

1. (a) What is the conversion of the CH₄ in the primary reformer? (b) What fraction of the hydrocarbon feed remains after the primary reformer (in stream F)?

2. (a) How much air is needed for the secondary reformer? (b) What is the conversion of the CH₄ in the secondary reformer?

3. (a) What is the conversion of CO to CO₂ in the shift reactor? (b) What is the composition of stream L (before the stream is separated)?

4. What % of the original water fed (stream W) is removed from Condenser 1 in stream C?

5. After the PSA step, what is the composition and flow-rate of: (a) the carbon-rich stream (T); (b) the ammonia synthesis feed stream (B)?

6. (a) Are there inerts in the ammonia section (bottom half) of the plant? (b) If so, what are they? (c) How much (molar flow rate and mole %) are in streams B, R, and RF?

7. (a) What is the single-pass conversion of N₂ (or H₂) in the ammonia reactor? (b) What is the overall conversion of N₂ (or H₂) in the ammonia reactor?

8. (a) For 100 mol/s of natural gas feed, how much ammonia is produced? (b) If the plant must produce 106 metric tons per year of ammonia, how much natural gas feed is necessary in metric tons per day and SCMH? Neglect the gas needed for the furnace. A year at the company consists of 350 days, 24 hours each day. SCMH = standard cubic meters/hr.

9. What % of the original hydrocarbon feed is lost in the purge stream?

10. FEED: If the natural gas feed and liquid water feed start at 25ºC and 1 atm, (a) How much heat (total) is needed to pre-heat all the feed to 600ºC isobarically? (b.) How much work (total) is needed to compress this feed mixture to 35 atm isothermally?

11. PRIMARY REFORMER: How much heat is needed for the primary reformer to have an exit temperature of 760ºC?

12. FURNACE FOR PRIMARY REFORMER: Additional natural gas is combusted with 25% excess air (both initially at 25ºC and 1 atm) to provide heat for the reformer. If half of this heat is perfectly transferred into the reformer: (a) For G = 100 mol/s, what flow rates of natural gas and air are needed? Assume the temperature of the combustion exhaust gases is 900ºC (b) If no heat was transferred to the reformer, what is the adiabatic flame temperature of the combustion reaction?

13. SECONDARY REFORMER: For the secondary reformer, air is pre-heated from 25ºC to 600ºC isobarically at 1 atm. (a) How much heat is required? (b) If the exhaust gases at 900ºC from (#12) are used to heat this air (with perfect efficiency), what is the final temperature of exhaust gases? (c) How much heat is necessary for the secondary reformer to have an exit temperature of 1000ºC?

14. SHIFT REACTOR: To avoid destroying the shift reactor catalyst, stream S must be cooled to 400ºC. (a) How much heat must be removed for this cooling? (b) How much heat must be removed for the shift reactor to have an exit temperature of 300ºC? (c.) If 500 mol/s of liquid water at 25ºC is used to remove this heat in a heat exchanger, what is the final temperature/phase of the water that leaves?

15. AMMONIA TURBINE: After the ammonia reactor, the stream passes through a turbine to expand the mixture and reduce the pressure. (a) How much work is obtained from expanding stream E (initially at 1000ºF) from 175 atm to 7 atm adiabatically? (b) What is the final temperature of this stream after the turbine? Recall design feature #17.

16. CONDENSER 2: (a) At 7 atm, ammonia condenses at what temperature? (b) How much heat must be removed to cool the streams to 0ºC? Assume (c.) Can room temperature water be used to accomplish this cooling? Why or why not? THINK CAREFULLY! Note: heat of condensation of ammonia at this T and P is ?Hcond = -21.875 kJ/mol. The heat capacity of liquid ammonia is 0.0808 kJ/molºC.

17. RECYCLE COMPRESSION: The recycle stream must be pumped back up to 175 atm before being mixed with stream B and sent into the reactor. (a) How much work is required to adiabatically compress stream R back to 175 atm? (b) What is the final temperature after compression?

18. MIXING POINT: (a) What is the final temperature of RF after stream R and B are mixed? (b) How much heat must be added to get this reactor feed mixture up to the reactor temperature of 1000ºF?

19. AMMONIA REACTOR: The ammonia reactor must operate at 1000ºF and 175 bar. How much heat is required to keep the NH3 reactor isothermal?

20. FINAL: In order for the ammonia plant to be profitable, the amount of ammonia produced MUST be greater than the total amount of natural gas used. It MUST also be at least 10% of the total amount of air used. What are these ratios? Is the plant profitable?

Attachment:- Chemical Project Assignment.rar

Reference no: EM131297143

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