What matters should be paid attention to by cement producers and processors when purchasing fans?

Cement production is a complex process with high dust, high temperature and multiple working conditions. As the core power equipment (used for raw material transportation, pulverized coal preparation, kiln tail ventilation, cooling and heat dissipation, etc.), the selection and adaptability of fans directly affect production efficiency, energy consumption cost and equipment life. When purchasing fans, cement manufacturers should focus on four core dimensions: matching process conditions, temperature and dust resistance, energy consumption and regulation, and safety and maintenance. The specific precautions are as follows:

First, give priority to matching the core requirements of "process links": the requirements of fans in different links vary greatly.

The fan function, medium characteristics (temperature, dust concentration) and air volume and pressure requirements of each link in cement production (such as raw material crushing, raw meal grinding, rotary kiln and cement grinding) are completely different. The first step must be to clarify the specific application scenarios of fans to avoid poor adaptability caused by "universal" selection.

Core requirements of process links, fan types, suggestions, key parameters and concerns

The high-temperature fan at the end of kiln is used to extract the high-temperature dusty flue gas at the end of rotary kiln (the temperature is 250~450℃, and the dust concentration is 100 ~ 300 g/nm). The high-temperature centrifugal fan (volute/impeller is made of heat-resistant steel) should be temperature-resistant and ≥450℃, and the impeller should be coated with wear-resistant coating, and the wind pressure should be stable (avoiding positive pressure in the kiln).

Raw material conveying fan pneumatically conveys raw meal/cement powder (at normal temperature, dust concentration is 500 ~ 1000 g/nm), and it is necessary to prevent dust accumulation and wear. The wind pressure of high-pressure centrifugal fan/roots blower is sufficient (to overcome the resistance of conveying pipeline) and the impeller is smooth (to prevent powder adhesion).

The pulverized coal preparation fan transports the mixture of hot air and pulverized coal (the temperature is 100~200℃, which is flammable and explosive). The explosion-proof and low-leakage explosion-proof centrifugal fan needs explosion-proof grade (Ex d IIB T4 and above) and sealing performance (to avoid leakage of pulverized coal).

The cooling fan is used to cool cement clinker/equipment (normal temperature, no dust or low dust), which requires large flow and low noise. The low-pressure centrifugal fan has sufficient air volume, low energy consumption and noise ≤85dB.

The dust-collecting fan is equipped with bag-type/electrostatic precipitator to extract dusty gas (temperature ≤200℃, high dust concentration). The impeller of the wear-resistant centrifugal fan, which needs anti-wear and anti-clogging, adopts wear-resistant materials (such as Mn13 steel) and the volute is easy to clean.

Second, focus on the three core properties of "temperature resistance, dust resistance and wear resistance": adapting to the harsh working conditions in the cement industry.

The high dust, high temperature and strong wear in the cement production environment are the main reasons for the failure of the fan, so it is necessary to check the material and structural design of the equipment when purchasing:

1. Temperature resistance: Select materials according to the temperature of the medium to avoid high-temperature deformation.

If the temperature of the medium is less than 150℃ (such as raw material conveying and cooling), ordinary Q235 steel plate can be used for the impeller/volute, with lower cost;

If the medium temperature is 150~350℃ (such as coal powder preparation and dust collection), heat-resistant steel (such as Q345R and 16MnR) should be selected to avoid strength reduction at high temperature;

If the medium temperature is above 350℃ (such as kiln tail fan and calciner fan), high-temperature alloy steel (such as 12Cr1MoV) must be selected, and the impeller needs to be dynamically balanced (it is easy to contract due to thermal expansion at high temperature);

Note: a temperature margin of 10%~20% should be reserved (for example, when the actual working condition is 300℃, choose a fan with a temperature tolerance above 350℃) to avoid short-term temperature fluctuation causing equipment damage.

2. Dust and abrasion resistance: optimize the structure and material for high dust working conditions.

The core failure points of fans in cement industry are impeller wear and dust accumulation and blockage of volute, so attention should be paid to when purchasing:

Material selection:

High-dust links (such as kiln tail and dust collection): Wear-resistant coatings (such as ceramic coatings and tungsten carbide coatings) are sprayed on the impeller surface, or wear-resistant castings (such as high chromium cast iron) are used to prolong the service life (the service life of ordinary steel plates is 3-6 months, and it can be extended to 1-2 years after wear-resistant treatment);

Easy-to-bond dust link (such as cement powder conveying): the impeller adopts "smooth curved surface design", and the inner wall of volute is polished to reduce powder bonding and accumulation.

Structural design:

Choose "forward-leaning impeller" (it is more resistant to blockage than backward-leaning impeller, and it is not easy to get stuck);

A "dust cleaning port" is reserved at the bottom of the volute (to facilitate regular cleaning of accumulated dust and avoid the decrease of air volume);

A "coarse filter" is installed at the inlet of the fan (to intercept large particles of impurities and prevent the impeller from being damaged by foreign objects).

Third, give consideration to "energy efficiency" and "adjustment flexibility": reduce long-term operating costs

The energy consumption of fans in cement industry accounts for 15%~25% of the total production energy consumption, so it is necessary to balance the "initial investment" and "long-term energy consumption" and adapt to the fluctuation of production load:

1. Give priority to "high-efficiency and energy-saving fans": check the energy efficiency grade.

Choose Grade 1 or Grade 2 energy efficiency fans that meet the Limits and Grades of Fan Energy Efficiency (GB 19761-2021) (Grade 1 energy efficiency is 15%~20% less than Grade 3 energy efficiency, and it can save tens of thousands of yuan in electricity bills if it runs for 8000h hours a year);

Avoid using "non-standard fans" (mostly inefficient and old models, with low initial price, but high energy consumption, short life and higher life cycle cost).

2. Select the regulation mode according to "load fluctuation characteristics": avoid energy consumption waste.

Cement production load often changes with the order quantity (such as full load in peak season and low load in off-season), and fan adjustment mode directly affects energy consumption:

Stable operation at full load (such as kiln tail fan): You can choose "inlet guide vane adjustment" (with high adjustment efficiency and energy consumption loss of only 5%~10%), which is more energy-saving than "outlet throttle adjustment" (energy consumption loss of 20%~30%);

Large load fluctuation (such as raw material conveying fan): it must be matched with "variable frequency speed regulation system" (air volume is directly proportional to rotating speed, power is directly proportional to rotating speed cubic, and energy saving is significant at low load, such as 50% load energy consumption is only 12.5% of full load);

Low flow and high pressure working conditions (such as small pneumatic conveying): Roots blower is more suitable (constant air volume characteristics, simple adjustment), but "variable frequency Roots blower" is needed (to avoid energy waste caused by bypass ventilation).

3. Accounting "actual demand parameters": avoid "big horse-drawn cars"

The air volume and pressure should be calculated according to the "process maximum demand+10% allowance" (the allowance is used to overcome the increase of pipeline resistance and the decrease of efficiency after equipment aging), but it should not be over-amplified (if the actual demand is 10,000 m/h, the fan with 15,000 m/h will be operated at low load for a long time, resulting in the decrease of efficiency and the increase of energy consumption);

If there are multiple similar working conditions (such as multiple cement mills), consider "parallel operation of fans" (more flexible than a single large fan, which can be started and stopped according to the load and reduce energy consumption).

Fourth, pay attention to "safety protection" and "maintenance convenience": reduce the risk of downtime.

Cement production has strong continuous operation, and fan failure will lead to shutdown of the whole line, so attention should be paid to safety design and maintenance costs when purchasing:

1. Safety protection: make special design for risk scenarios.

Explosion-proof requirements: the fans supporting the pulverized coal preparation and fuel system must meet the explosion-proof standards (Ex d IIB T4 or higher), and the motors, junction boxes and bearing seats should be explosion-proof to avoid dust/oil gas explosion when meeting sparks;

Overload protection: it is equipped with "temperature sensor" (monitoring bearing temperature, alarming for over-temperature), "vibration sensor" (stopping due to excessive vibration) and "current protector" (avoiding motor overload and burning);

Sealing performance: high temperature/high dust fans need to choose "mechanical seal" or "labyrinth seal" (the leakage is more than 90% lower than that of ordinary packing seal to avoid dust leakage polluting the environment or entering the bearing to cause wear).

2. Maintenance convenience: reduce maintenance time and cost.

Structural design:

Select "detachable volute" (it is convenient for the maintenance of impeller and bearing, and it is not necessary to disassemble the fan as a whole);

External bearing seat (avoiding direct heating of bearing by high temperature medium, prolonging bearing life and facilitating lubricating oil filling);

Fitting of wearing parts:

Impeller, bearing, seal and other vulnerable parts need to be standardized (universal model, which is convenient for quick purchase and replacement and reduces downtime);

Ask the manufacturer whether to provide "spare parts package" and "on-site maintenance service" (especially for manufacturers in remote areas, it is necessary to ensure timely after-sales response).

V. Other key points for attention

Qualification verification of manufacturers: select manufacturers with "special production qualification of fans in cement industry" (not general fan manufacturers), which have a better understanding of cement working conditions and the equipment design is more in line with actual needs (cases in the same industry, such as proof of supply for a large cement group, may be required);

Noise control: If the factory is located near a residential area, it is necessary to choose a "low-noise fan" (running noise ≤85dB), or require the manufacturer to provide a "sound insulation cover" and a "muffler" (to avoid being punished by environmental protection for excessive noise);

Life cycle cost accounting: not only look at the initial equipment price, but also calculate "energy consumption cost+maintenance cost+replacement cost" (for example, an efficient fan is 100,000 yuan more expensive than a common fan, but it saves 50,000 yuan annually, and the difference can be recovered in two years, which is more cost-effective in the long run).

summary

The core logic of selecting fans for cement manufacturers is "priority should be given to working conditions, and equal attention should be paid to energy saving and safety";

Firstly, the process links of fan application (such as kiln tail, transportation and dust collection) are defined, and the core parameters of temperature, dust, air volume and wind pressure are determined;

Select materials and structures with high temperature resistance and wear resistance (such as heat-resistant steel for high-temperature fans and wear-resistant coating for high-dust fans);

Give priority to high-efficiency and energy-saving models, and match with adaptive adjustment mode (frequency conversion/imported guide vanes) to reduce long-term energy consumption;

Pay attention to safety protection (explosion-proof, overload protection) and maintenance convenience to reduce the risk of downtime.

Finally, through "parameter matching+cost accounting+manufacturer screening", the fan that is most suitable for its own production needs is selected to achieve "efficient, energy-saving and stable" operation.