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Boiler fans have numerous noise sources and high decibel levels, which are significant factors contributing to environmental complaints. Starting from the prevention and control of boiler fan noise, this article discusses the hazards of fan noise as well as comprehensive noise reduction and energy-saving treatment technologies. Currently, in many enterprises, due to industrial production and heating needs, the installation and use of boilers are very common. However, due to factors such as poor location selection and inadequate fan performance, many boilers generate noise that disrupts the peaceful working and living conditions of residents in the surrounding area, harms people’s health, and often leads to disturbances and disputes. According to statistics, in 2004, complaints related to noise in our region accounted for 30% of all environmental complaints. Therefore, noise control for boiler fans is becoming increasingly important. 1. The hazards of environmental noise pollution. The effects and harms of noise on the human body can generally be divided into two aspects: occupational health protection and environmental protection. The former refers to the harm caused to human health, leading to the occurrence of various diseases, while the latter refers to the disruption of environmental tranquility, which affects people’s normal work and life. The main hazards of noise to human health include damage to hearing, leading to noise-induced deafness ； It causes excitation of the cerebral cortex and imbalance, as well as damage to cerebral blood vessel function, leading to neurasthenia ； It damages the cardiovascular system, causes digestive disorders, and affects the endocrine system ； It disrupts people’s normal life, rest, verbal communication, and daily work and study, distracts their attention, and reduces work efficiency. 2. Basic principles of noise control. There are three main factors that contribute to noise pollution: the sound source, the medium through which sound propagates, and the receiver. Only when these three exist simultaneously can they cause interference for the listener. By focusing on these three aspects and employing methods such as reducing sound sources, limiting the propagation of noise, and preventing its reception, it is possible to control noise. As for specific noise control techniques, three approaches can be used: sound absorption, sound insulation, and noise cancellation. 2.1 Sound absorption: When sound waves strike the surface of an object, some of the sound energy is absorbed by the object and converted into other forms of energy; this phenomenon is known as sound absorption. The sound-absorbing performance of a material is expressed by the absorption coefficient; the higher this coefficient, the better the material’s sound-absorbing capabilities. The sound absorption performance of a material is related to the properties and structure of the material, as well as the angle of incidence of the sound waves and their frequency. The sound absorption mechanism of porous sound-absorbing materials is as follows: these materials contain countless tiny, interconnected pores. When sound waves strike the surface of such materials and then enter these tiny pores, it causes the air within the pores to move. The air adjacent to the pore walls and fiber surfaces, however, moves with difficulty due to frictional and viscous resistance, which results in the conversion of sound energy into heat energy, thereby dissipating it. Therefore, good acoustic absorption materials need to be porous, with the pores interconnected, and these interconnected pores must be in communication with the outside world so that sound waves can enter the interior of the material. For sound waves at 1000 Hz, the sound absorption coefficient of 10 cm thick ultra-fine glass wool is 0.87. 2.2 Sound insulation: The method used for sound insulation is to enclose the noise source, keeping the noise within a confined space; such a sound insulation structure is known as a sound insulation enclosure. When sound waves encounter a shield, due to the change in the characteristic impedance at the interface, part of the incident acoustic energy is reflected, part is absorbed, and part penetrates the shield and continues to propagate. The sound insulation performance of a material can be expressed by the sound transmission coefficient. The smaller the sound transmission coefficient, the less sound energy passes through, indicating better sound insulation performance of the material. The sound insulation performance of a material is related to the structure and properties of the sound insulator, as well as the frequency of the incident sound waves. 2.3 Noise reduction: Noise reduction is achieved by attaching porous sound-absorbing materials to the inner walls of air flow channels, or fixing them in pipes in a specific manner, in order to reduce aerodynamic noise. The level of noise reduction can generally reach 10–50 decibels. 3. Fan noise control techniques: The noise level of the blowers and exhaust fans in boiler rooms is generally around 90 decibels. Since the temperature of the boiler smoke being transported is as high as 180°C, using sound-insulating enclosures can lead to poor heat dissipation, excessive temperatures in the motors, and even motor damage. Therefore, in terms of process design, noise reduction and energy savings of the fan are combined. Through practical experience, the comprehensive energy-saving and noise-reduction solution for boiler fans is as follows: the process layout of the boiler room remains unchanged; the blower and exhaust fan are placed in sound-insulated chambers, connected to the main unit via ventilation ducts. Air inlets are provided on the ceiling or walls of these sound-insulated chambers, and silencers are installed for air intake into the machine room. In the layout, place the blower on the side closest to the boiler room, with the air inlet on the upwind side and the motor located in the middle of the airflow path. When the boiler is in operation, the blower creates a negative pressure inside the sound-insulated chamber, which allows a large amount of fresh outdoor air to enter automatically. This air first exchanges heat with the fan motor, cooling it down, thereby keeping the indoor temperature at around 50°C. In this scheme, since both the soundproof room and the inlet silencer have high noise reduction capabilities, achieving good noise reduction results is easy. The blower sends the preheated air into the boiler for combustion, thereby reusing energy and offering certain economic benefits. To ensure effective governance and the proper operation of boiler equipment, during design and construction, it is necessary to take into account factors such as noise intensity and frequency based on specific requirements, and to carry out detailed design for sound insulation, sound absorption, as well as ventilation and heat dissipation, with careful attention to detail. Calculate the size and thickness of the soundproof room, as well as the type and thickness of the sound-absorbing materials. The noise reduction level of the inlet silencer is generally set at around 25 dB(A). Minimize the area from which noise is radiated by removing unnecessary metal panels. Control the vibration of the panel by using flexible materials to connect the sound source with the sound insulation enclosure and the foundation. The connection pipes of the blower and the thin-walled steel chimney represent weak points in noise control; 5 cm thick glass fiber insulation is wrapped around the pipe walls, secured with steel wire, and then the surface is painted with 2 cm thick wire mesh cement. The glass fiber cotton is fixed to the steel plate to absorb the reverberant noise inside the sound insulation room. 4. Noise reduction and energy-saving effects 4.1 Noise reduction effect: If the noise level of the fan is 90 decibels, a sound-insulating cover made of 3mm steel plate can provide a theoretical sound insulation level of 32 decibels. The sound-insulating enclosure is lined with 10 cm thick glass wool, whose sound absorption coefficient is 0.87. A silencer is installed on the air inlet pipe, resulting in an actual sound insulation level of TL=32+10 log20.87=30 decibels. Thus, after noise reduction measures are applied to the fan, the noise level becomes T=90-30=60 decibels. Sound pressure level and sound intensity are objective physical quantities that describe sound, while the human subjective perception of noise is expressed in terms of loudness: N=2(N-40)/10 (Sone). The loudness of the fan before treatment was N1=2(90-40)/10=32 Sones, and after treatment it was N2=2(60-40)/10=4 Sones. Hence, the loudness decreased by 87.5% after the treatment. As for energy savings, the heat dissipation of equipment in the machine room occurs through three main mechanisms: ① convective heat dissipation between the exhaust fan and the pipe walls, ② radiative heat dissipation between the exhaust fan and the pipe walls, and ③ heat dissipation from the fan motor itself. Based on the principles of ventilation engineering, energy-saving and noise-reduction systems can also recover some heat. Through practical application, the noise reduction and energy-saving technology for boiler fans not only reduces noise pollution and safeguards the living environment of the public, but also recycles energy, achieving a balance between economic and environmental benefits.