Reduce your carbon footprint
Published: 08 July, 2011
PWE looks at how proper alignment can reduce your carbon footprint as well as your electricity bill. This case study was done at Lake Erie Steel, a large steel mill in Nanticoke Ontario, USA. Measurements were made by Cliff Dosser, Industrial Mechanic and his team of apprentices and Coop Students.
The problem
Alignment of the long jack-shafts on the water-cooling towers. This was previously done using a single beam system that could not span the required distance of fifteen feet from the motor to gearbox. The procedure for this type of system had been to
measure at each coupling on either end of the jack shaft and then use both sets of alignment results to calculate the necessary correction in order to align the machine units.
The steel mill purchased an Easy-Laser, dual beam, shaft alignment system. Spanning the fifteen feet coupling to coupling is not a problem for the Easy-Laser that is capable of shaft alignment over a distance of sixty feet.
Rough alignment
A rough alignment is made to ensure that the laser beam hit the detector surface in all three measurement positions. One laser/detector was mounted on the motor shaft. The second laser/detector was mounted on the gearbox shaft. There-by doing true shaft to shaft alignment that was not possible previously.
The laser beams were centred in the closed target at the 9 o’clock position. The shaft was then rotated to the 3 o’clock position. In this case it showed that the alignment was grossly out so corrective action began.
Measurement procedure
Now with the laser target doors open, measurements were recorded in as little as forty degrees of shaft rotation. The display showed real time readings in both the horizontal and vertical planes for the moveable machine.
The moveable machine is usually the motor however it is possible to change the configuration of the machine in the laser display if the driven (gearbox) unit is to be moved or even a combination of different machine feet.
Adjusting the machine
The trick is in choosing the correction that requires the least amount of movement. Now all that was needed was to re-position the machine but the real skill was in controlling the movement. At a distance of fifteen feet you don’t bump anything; it’s a gradual move, which is best done with jacking bolts. The work was completed and the unit was put back in service.
Savings
Cliff took an initial amperage reading on the unit before the realignment and it was found to be 174 amps. After the work was completed another reading was taken showing 155 amps. That’s a whopping 19 amp drop.
Although Lake Erie Steel is running almost 24/7 it was estimated that the cooling tower ran half the year as it is not required in the winter months. That equates to 4380 running hours so a 19 amp drop works out to a little over 10% in energy reduction which would be 78,735 Kilowatt hours saved. Using the average of 0.07 cents per kW, a savings of $5511.44 (£3445) per year is achieved.
Summary
Traditionally, maintenance departments do not sing their own praises. In many companies the maintenance departments are still considered to be a necessary expense instead of a profit centre. This perception is starting to change as improved maintenance procedures demonstrate cost savings that go directly to the company’s bottom line by reducing the energy costs and improving reliability.
The end result is that the team has not only reduced the plant’s overall carbon footprint by reducing energy that relates to 54 metric tons of CO2, or the
equivalent of 8.2 cars off the road, but they have also done a good job of re-aligning the motor and gearbox which means that, barring unforeseen circumstances, the plant will get the optimum life out of the cooling tower drive.
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