18-12-2012, 01:57 PM
Compressed Air Project Improves Efficiency and Production at Harland Publishing Facility
Compressed Air Project Improves Efficiency.pdf (Size: 171.25 KB / Downloads: 33)
Project Overview
The new printing machines’ greater demand for compressed air led the Atlanta facility to commission
an independent review of these new machines to best determine how much additional compressor
capacity was needed. This review was conducted by Air System Management, an OIT BestPractices
Allied Partner.The operators felt that the review was particularly necessary because they planned to
reconfigure the new printing machines to print at a higher rate, which would cause them to demand
even more air.
The review began by base-lining the new printing machines’ compressed air needs. The examination
revealed that the machines had three components that consumed compressed air at differing volumes
and pressure levels: batching modules (20 scfm at 130 psig), collators (1.1 scfm at 100 psig), and
print engines (also 1.1 scfm at 100 psig). The machines came with one-hp onboard compressors that
were intended to supply the collators and print engines. The batching modules’ air demand required
that they be supplied by the main compressed air system. Once installed, the new printing machines
more than doubled the facility’s compressed air demand to over 600 scfm, forcing an increase in the
header pressure to 130 psig. In addition, the site planned to configure the printing machines to operate
at 138 pages per minute, which would increase each batching module’s consumption from 20 to 27 scfm.
Further examination of the batching modules revealed that within their pneumatic systems, a series
of open-blowing air bars caused the greatest demand for compressed air. The evaluation also found
that two of the other components in the batching modules, the joggers and lift cylinders, were unable to
work properly at the manufacturer’s recommended pressure levels. The manufacturer’s recommended
pressures for the joggers and lift cylinders were 65 psig and 80 psig, respectively. However, the
Atlanta facility had to supply them at no less than 118 psig and 125 psig because the air feeding those
bars was taken upstream of the lubricator and regulators for use by the joggers and lift cylinders. To
the main compressed air system, this situation was similar to a leak and meant that the header
pressure had to be increased to satisfy the pressure and volume requirements downstream. In addition,
the hoses supplying the batching modules from the airdrops were too small for the volume of air they
had to accommodate, and there was a leakage rate of 2 scfm within the batching modules.
Project Implementation
To optimize the new printing machines, the Atlanta site personnel decided to have the machines
redesigned to reduce their compressed air consumption. Working with the Original Equipment
Manufacturer (OEM), Harland was able to configure the batching module so that the air bars would
not require compressed air. Instead, each module was fitted with an onboard, two-stage, 2-hp blower.
The air coming from the blowers would be pulsed through a series of solenoid-operated air
valves for the air bars to use.
The Atlanta plant personnel also replaced the distribution hoses between the batching modules
and the main header, and the hoses between the control valves and components within the
modules. The replacement hoses were shorter and wider, allowing for better airflow. In addition,
lubricators were reinstalled downstream of the air regulators to prevent the regulators from getting
dirty and operating poorly. Finally, each module was provided with a dedicated storage tank.
The storage tanks were added because the different pressure requirements of the joggers and
lift cylinders would cause compressed air to be diverted from one application when another one
actuated. When the new printing machines had first been installed, the site overcame this problem
by increasing pressure to the entire machine. Now, the pressure to this machine could be
lowered to 80 psig or less.
Results
The printing machine redesign, and the measures to lower end-use pressure
requirements, allowed Harland to reduce the new printing machines’
compressed air needs and increase their efficiency. Once the OEM
reconfigured the printing machines at the Atlanta site so that the air bars no
longer required compressed air, each machine’s air demand declined from
27 scfm to only 4.5 scfm. In addition, the need for high-pressure air was
eliminated. The storage for the joggers and lift cylinders, along with
appropriately sized distribution hoses, further helped stabilize the pressure
within the batching modules. This reduced the site’s total air demand to
approximately 300 scfm at 81 psig, allowing the facility to take 70 hp of
compressor capacity offline.
The redesigned printing machines, with onboard compressors taken offline,
have an annual compressed air energy cost of $310 per machine, or
$21,700 for the company’s 70 machines. Had the printing machines not
been redesigned, and the onboard compressors left online, the annual
compressed air energy costs would have been $3,103 per machine, and
$217,210 company-wide. As a result, Harland avoided having to purchase
between 500 and 600 hp of compressor capacity, which would have cost
$500,000. The avoided costs more than offset the $300,000 spent to redesign
the 70 printing machines. Because fewer compressors were needed, Harland
was able to spend less on maintenance. The company gained backup
compressor capacity and reduced the possibility of production downtime.
Harland also benefited from increased product quality and decreased
production cycle time.