Efficient Plant Jan./Feb. 2024 - 17

feature | compressed air
Left. The excess heat that results from compressing air can save signifi cant
money if captured and repurposed.
used to heat the facility in the winter months. In summer months or for
operations in warmer climates, the excess heat can be sent outside to
help keep the facility cool. In this application, the air is typically heated
to a higher temperature than in a pre-heated makeup-air application.
More ductwork may be required to distribute the heated air and a higher-fl
ow compressor package fan or added downstream booster fans
may be necessary, depending on the size of the facility and the number
of compressors contributing heat.
With either application, supplementary or pre-heating, use of a
thermostatically controlled heat-recovery system drawing in outside
air can increase savings by reducing infi ltrations while providing usable
heat. A system without this level of control may not be able to heat the
outside air enough to provide adequate environment heating.
Depending on the production facility, the heated air may be used for
product drying and similar applications. Th e sky's the limit as to what
function the recovered hot air can provide.
WATER-BASED APPLICATIONS
While heat recovery from the cooling airfl ow can be eff ective, there are
other methods to recover and use the heat generated when compressing
air. On a water-cooled compressor, the machine is fed water either
from a municipal supply or a closed-loop system. Th is water is used to
cool the fl uid and compressed-air streams and transfer the heat of compression
to the cooling water. Th is heated water can then be used for
various applications such as pre-heated boiler water or process water.
Since a compressor can use signifi cant amounts of water to meet
the cooling needs and varying loads can lead to temperature fl uctuations,
there can be challenges in using the primary cooling water. In
this instance, the compressor can be outfi tted with an additional heat
exchanger to transfer the heat of compression to a supplementary water
fl ow. Th e fl ow and temperature of the water can then be more tightly
controlled and tailored to the application.
If the compressor's cooling needs are not being met by this stream of
water, its primary cooling system can take up the slack. Additionally,
this type of system can be outfi tted to an air-cooled machine, allowing
heat recovery to a specifi c water use without the need for a full
water-cooled machine. Using water for heat recovery allows year-round
use and can recover as much as 85% of the energy required to compress
air. Th is type of system may also off er reduced investment by avoiding
the need for extensive ductwork.
Calculating potential savings and payback of a compressor heatrecovery
system can vary, depending on the compressor size, operating
conditions, local energy rates, use and location of the recovered heat,
and the initial investment. For example, a 300-hp compressor can generate
12,378 BTU/min. Th is represents 7.42 therms/hr. of useable heat,
worth as much as $4,000/1,000 hr. of compressor operation at roughly
$0.50/therm. Annual heating-cost savings can reach $15,000 without
negatively impacting the compressor cooling effi ciency.
Whatever your needs for reclaimed heat, the possibilities are many
and the energy savings are signifi cant. Using byproducts to maximize
effi ciency is worth the time and investment. EP
Jeremy Sickmiller is Director of New Product Development Engineering
at Hitachi Global Air Power, Michigan City, IN (hitachiglobalairpower.com).
+
SCAN
FOR MORE
Scan the code to learn more
about Sullair products and
services.
america.sullair.com/en
MULTI-PURPOSE
COMPACT
Fits through
doorways &
inside elevators
MULTI-PURPOSE
RIGGING
(No operator license required)
EXTENDED
(No operator license required)
EXTENDED
20ft. up
www.micr ocrane s.com
140ft. down
www.micr ocrane s.com
JAN/FEB 2024
EFFICIENTPLANTMAG.COM | 17
http://www.power.com http://america.sullair.com/en http://www.microcranes.com http://www.EFFICIENTPLANTMAG.COM
Efficient Plant Jan./Feb. 2024

Table of Contents for the Digital Edition of Efficient Plant Jan./Feb. 2024
