Suggested Response - Q3

*** Your brewery requires nitrogen for a particular process. Compare the options available for supplying nitrogen to the plant, and make recommendations. What criteria would influence your choice?

The plant manager has confirmed that only gas is required, but they are expecting to use large volumes as it will be used for vessel top pressure and purging gas.

Response:

Nitrogen can be supplied in gas cylinders, liquid cylinders, or bulk liquid. It can also be generated on-site.

Gas cylinders will not be feasible given the large volumes required. Liquid cylinders would also require frequent deliveries. Thus, the two options left to compare would be bulk liquid nitrogen and on-site nitrogen gas generation.

Bulk liquid would require the installation of a liquid storage tank, vaporiser, and pressure control to the brewery.

On-site nitrogen gas generation would require a nitrogen generator, a nitrogen receiver, and pressure control to the brewery.

Bulk liquid has the following advantages and disadvantages:

Advantages

  • High purities

  • Flexible supply as high volumes of gas can be quickly generated with an adequately sized vaporiser

  • Potential for low capital costs if the installation is supplied by the supplier

  • Low on-site electricity requirements

  • Low maintenance requirements

Disadvantages

  • High transport costs

  • Deliveries have to be managed

  • More expensive than on-site generation

  • Losses due to system vaporisation can be as high as 20%

 

On-site nitrogen gas generation has the following advantages and disadvantages:

Advantages

  • Lower overall cost to produce versus purchasing

  • No transport required

  • No losses

Disadvantages

  • Capital investment required

  • Difficulty in dealing with huge fluctuations in demand unless equipment is sized for largest possible demand

  • Maintenance required for the gas generation equipment

  • Redundancy required for breakdowns or contingency measures to ensure uninterrupted supply

  • Uses electrical power, which adds to energy footprint and maximum demand

 

Based on the above, it would seem that on-site generation is the best choice in most circumstances. However, the following criteria are important to consider:

  • Is capital available to purchase the equipment?

  • Can the maintenance be done in-house or easily outsourced?

  • Is there enough electrical capacity to run the nitrogen generator?

  • What is the cost difference between the bulk liquid nitrogen and the on-site generated nitrogen, based on a total cost of generation including capital costs?

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