Page 76 - Industrial Plants

applied to a specific project. What is important to note
is that the various expediencies are not always “Our Companies started the
independent of each other, and related effectiveness discussions over the Preliminary
can increase significantly in case of joint application Specifications for the three Air Cooled
with other expediencies. For instance, the use of low Heat Exchangers destined
noise fans is more effective at reduced air flow rates, for a gas compression station
which must be compensated by an increased heat in Denmark in 2019
exchange surface.
Although the operating pressure of the process fluid
Case study: (i.e., natural gas) was relatively high, namely 113 bar-g
Gas compression station at 92°C, the main concerns were related to the
maximum allowable noise level only, which was
in 2019, we started the discussions over the Preliminary tremendously low. The plant was planned to be located
Specifications for the three Air Cooled Heat Exchangers in a rural area, at a distance of about 500 m from some
destined for a gas compression station in Denmark. At residential buildings and, according to the EIA permit,
that time, Renco was preparing their Bid to win the the maximum noise emission at these critical points
Project and asked Boldrocchi to co-operate and should have been limited to 35dB(A). Based on
support in order to develop a solution suitable for the preliminary estimations, the Air Cooled Heat Exchangers
specific needs. had been identified as the major noise sources of the
Plant, whereas the other machinery were not critical, as
they were considered to be installed inside insulated
buildings.

The maximum allowable Noise Power Level of each air
cooler running at full load was limited to 87 dB(A),
based on the noise spreading simulations and the
resulting expected noise level at the residential
buildings.
The cooperation between Renco and Boldrocchi
allowed the starting of the design process without
considering any footprint constraints, nor requirements
related to the type of fans, motors, and other noise
affecting parts. This degree of freedom allowed for the
identification of the optimal technical and cost-effective
solution. Then, some adjustments have been applied
to the proposed design, to better integrate the air
coolers within the overall plant.

Noise driven design of Air Cooled
Heat Exchangers

Coming back to the origins, the noise-driven design
started from the identification of a base solution,
compliant with the process needs (i.e., cooling of
the given natural gas stream), but exceeding the
noise requirement. The first two adjustments applied
to the design have been the adoption of bell-shaped
fan rings and the reduction of the fans rotational
speed, as shown in the left side of Figure 4.
However, this allowed only for a slight reduction of
noise to be obtained, which was furtherly improved
when low noise type fans were considered in place
Figure 3: Aerial view of the Gas Compressor station during assembly at site. of regular fans. The specific characteristics of the
The air coolers are shown in the right side of the figure whereas the left side selected low noise fans allowed further reduction of
shows the compressors buildings. (Renco S.p.a.) the rotational speed, to a level that was not possible

IndustrIal Plants - May 2022
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