- 1) Silencers
- 2) Enclosures
- 3) Engineering Analysis
Silencers
1. Exhaust Silencer for Coal-fired Power Plant
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The client approached V.H.I.D to help silence the noise generated by their Induced Draft Fans. These fans are responsible for discharging flue gas through the ducts and out the exhaust stack.
- Design Challenges:
- High temperature flue gas
- Large duct size
- Pipe Bridge located directly above the duct blocked baffle access to inside the duct
- Fly ash particulate in the stream
- Low pressure drop requirement
- Stringent installation timeline
Through V.H.I.D’s reliable system assessment, definition, modelling, and
design, all noise and pressure drop specifications were met. The difficulty
in transporting and installing full-size silencer baffles was overcome by
designing each baffle in three sections. Also, a special hinge connection
design for the support structure was implemented to handle thermal expansions
in the silencer casing. Not only did V.H.I.D’s management skills allow the
stringent installation timeline to be met, but site supervision and trouble-shooting
was provided as well.
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2. Intake Silencer System for Gas Turbine Testing Facility
The client requested a universal intake silencer system for their jet engine test cell, which housed the testing of different engines. V.H.I.D’s scope for the intake silencer system included: Filter house, Silencer, Conical transition, Support Structure.
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- Design Challenges:
- Tight near-field noise criteria
- Limited space on test cell roof top for installation
- Request for special filter house electrical features
- Weight limitation
V.H.I.D’s commitment and capability to meet strict noise reduction specifications
is illustrated in this project. Many design iterations were made in order
to optimize the usage of space and silencer performance. The combined efforts
of the final silencer shape, tightly spaced baffles, and lagging around the
casing allowed for the noise criteria to be met. Other special features of
this intake system include filter house louvers for weather protection, ease
of installation, and height adjustment flexibility to overcome discrepancies
in drawing and actual site dimensions.
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3. Retrofit of Exhaust Silencer for Jet Engine Test Cell
The client’s jet engine test cell had an existing exhaust silencer in place, but needed to be retrofitted to suit an engine of higher thrust.
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- Design Challenges:
- Limitation on silencer size
- High velocity
- Short transition from elbow to silencer inlet
In minimizing costs for this project, V.H.I.D reused as much of the existing
silencer as possible. However, all reused components were inspected to ensure
they were free from defects. For the silencer design, acoustic, aerodynamic,
thermodynamic, and structural analyses were performed. Special acoustic fill
was deemed necessary for withstanding high airflow velocity, and an inlet
diffuser was redesigned to ensure uniform airflow distribution.
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4. Reactive Exhaust Silencer
The client is a foundry for industrial components such as conditioning/refrigeration, automotive, and heavy truck parts. They approached V.H.I.D to design and fabricate a silencer for their wet scrubber system.
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- Design Challenges:
- Corrosive environment – chlorides in water
- Steam and dust in gas stream
- Required baffles to be accessed easily for cleaning
Due to the corrosive nature of this system, conventional absorptive silencers
were not adequate to meet its specifications. Instead, V.H.I.D decided to
use reactive baffles so that acoustic fill could be eliminated. Furthermore,
the silencer was constructed with a ferritic stainless steel, which is cost
effective and offers reliable corrosion resistance. This silencer delivers
good noise reduction, has minimal affect on pressure drop, and includes a
baffle pull-out mechanism for easy baffle cleaning access.
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Enclosures
5. High Transmission Loss Noise Control Enclosure
The client had an extremely noisy mechanical shaker at one of their testing facilities, used for fatigue testing on aircraft components. They came to V.H.I.D for a solution to attenuate this noise.
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- Design Challenges:
- High sound pressure level mainly at low frequencies
- Reverberation within steel building in which the mechanical shaker is housed
An industrial acoustic enclosure was designed and fabricated to attenuate
the noise generated by the mechanical shaker. The enclosure panels had a high
transmission loss with the use of a high mass septum, and its thickness was
specially designed for this application. A high transmission loss was also
designed for the door and window, which had special seals to prevent noise
leakage. Ventilation within the enclosure was achieved with an intake and
exhaust silencer. This unit was fully assembled prior to delivery, making
the installation extremely convenient.
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Engineering Analysis
6. Vibration Measurement & Analysis
The client first recognized a vibration problem with their black liquor reformer when cracks were observed on all diagonal bracing of the silo support structure. To aid the client in finding a solution to this problem, V.H.I.D was invited to analyze the nature of the vibration. V.H.I.D gathered acceleration and displacement data on different points of the structure, as well as on different dates. Our analyses included: general vibration magnitude at significant points on the structure, relationship of vibration magnitudes in different directions, and types of vibration involved. Finally, software was used for a modal analysis of the silo support structure in order to further understand the nature of the vibration involved.
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