How A Production Facility Reduced Their Operating Costs With In-House Nitrogen Generation

A customer found themselves frustrated with the high cost of bulk nitrogen and the associated fees of their nitrogen contract. The company called on Diversified Air Systems (DAS), a Motion & Control Enterprises (MCE) company, to help figure out a more cost-effective solution.

After learning the extent at which the company was overpaying for higher nitrogen levels than they needed, the customer canceled the contract. The team switched to MCE and selected a nitrogen generator at their needed nitrogen levels.

Switching to an N2 generator resulted in full recovery of the project cost and big savings.

Consistent operations included five laser cutters; the manufacturing facility was using bulk liquid nitrogen for their laser machines. The flow requirement was maintained at an average of 50 SCFM @ 120 PSI.

The customer was spending $6,000/week for bulk liquid nitrogen along with the affiliated fees and taxes. Their process did not require 99.999% purity, however, that was the way it was delivered – no choice.

This customer, like many others, was required to sign an evergreen contract which meant they had a very brief window to opt-out of renewal before it automatically renewed for another term.

However, this customer was shrewd. Shrewd in respect to the contract wording as far as disruptions in manufacturing operation due to the supply of nitrogen.

In each case during, the calendar years of 2020 and 2021, the customer went days without nitrogen due to the bulk liquid supplier’s inability to provide the contracted amount. With careful documentation the customer could cancel the contract at any time.

Discontented with the continued experience, this customer had explored nitrogen generation because of the excessive cost of bulk liquid and the costly downtime it had caused.

THE SOLUTION:

MCE’S PRODUCT & PROCESS EXPERTISE

Siemens Simatic HMI

Design Specification – MNG-US-1820

Diversified Air Systems (DAS) in Pittsburgh, PA, an MCE company, had just the right answer for this customer.

At first, DAS engaged in the discovery process to determine the flow, pressure, and purity requirements.

• The pressure varied based on the thickness of the cut from 9 bar to 20 bar.

• The flow was calculated using an inline mounted flow meter to look at two weeks to one month of data.

• It was concluded that the flow ranged from 7 to 64 CFM @ a desired purity of 99.95%.

This would require a separate air compressor which produced 356 CFM at 125 PSI

A variable speed compressor was chosen with turn down capability of 80% due to the linear relationship to electrical usage and to obtain the most efficient system. A wet receiver tank was used before the refrigerated dryer, and a dry tank of the same size was used just prior to the nitrogen generator. This storage allowed for more separation of water prior to the dryer – storage of dry air after the dryer – and before the nitrogen generator. The net result was a 6:1 storage ratio before the nitrogen generator.

The generator was sized to produce up to 68 CFM of nitrogen, at a purity of 99.95%, at a discharge pressure of 116 PSI. Once the nitrogen was discharged a buffer tank was used to store the nitrogen to account for slight swings in purity due to the towers switching during the pressure swing adsorption process.

Not only was a buffer tank utilized but an additional low pressure storage tank was also included to precede the booster compressor. The booster compressor would boost the nitrogen pressure to 400 – 450 PSI.

And finally, after the booster a high-pressure storage tank was used to smooth out any fluctuations during the larger demand thicker cuts.

While the customer was continuing to utilize their existing bulk liquids as a source for nitrogen from previous deliveries, its days were numbered.

In fact, in less than 24 hours the line that fed the plant from the bulk liquid tank was shut off with a valve and the nitrogen generator connected directly to that plant feed line and fully operational at 99.995%

They maintained the flow meter installed slightly down stream and kept it in the systems for tracking of pay back and usage.

THE RESULTS:

THE COMPANY FULLY RECOVERED THEIR PROJECT COSTS, INCREASED SAVINGS, & EXPANDED THEIR OPERATIONS

ONE WEEK FOLLOW UP

As the customer continued to become acclimated to the new unit, they reported that multiple times they have forgotten that the new system has even been installed! Thanks to the customers keen eye on their evergreen contract details, the customer was able to successfully cancel any future deliveries of the bulk liquid nitrogen with their supplier.

The laser cutting operations have also reported positive feedback. The laser cuts are clean and are of exceptional quality. Previously planned, a new and larger laser cutter is now being installed at the manufacturing facility.

ONE MONTH FOLLOW UP

After the first month the customer has begun using the high-pressure booster for thicknesses of 1/8” through 3/8” stainless steel for the military. Cuts have remained exceptionally clean, and the purity level is at 99.96%.

The annual maintenance with all supplies is the cost of one week on what they were paying for bulk liquid nitrogen. And the electricity use did factor in the equation. The value-lesson learned here is that every application is different. So why must a company overpay for 99.99999% purity when it is not needed?

Keep in mind that the 99.999% purity is easily attainable with pressure swing adsorption.

Additionally, the purity level can be adjusted in a nitrogen generation system to lower levels depending on the individual needs of the plant.

SIX MONTH FOLLOW UP

The customer has continued to recognize the savings and the positive results. The entire project cost has been fully recovered from the savings derived. They have invested in an additional laser table and are expanding their operations.

The pay back was recognized in 26 weeks.

18 MONTH FOLLOW UP

As time went by and weeks became months, their anticipated company growth is on-track and they continue to reap benefits, reduce costs, and have since added another laser table.

The nitrogen generation system has been in service for approximately 18 months. Yielding a minimum monthly savings of over $20,000!

Are you ready to cancel your evergreen contracts and start saving with in-house nitrogen generation?

Don't wait, contact us today!