boiler flue dilution fan

boiler flue dilution fan

The boiler flue dilution fan is suitable for 0.5~35t/h industrial boiler equipped with coal-saving unit(preheater)and smoke prevention and dust control unit. It can be selected by similar inlet condition and performance, but the maximum inlet temperature should not exceed 250℃.
Product description

Product features:
1.Boiler flue dilution fan can operate at high efficiency area when industry boiler operate in changing operation condition. The purpose of energy-saving is reached. The fan is joint designed by the fan energy-saving group of Mechanical Building Industry Department and the famous factory of state fan trade. It is highly effective products which mainly recommended by State Economic and Trade Commission and Department of Mechanical Building Industry. It has advantages of highly efficiency, low noise and wide range highly effective area of performance curves.

2.The boiler flue dilution fan is suitable for 0.5~35t/h industrial boiler equipped with coal-saving unit(preheater)and smoke prevention and dust control unit. It can be selected by similar inlet condition and performance, but the maximum inlet temperature should not exceed 250℃. Dust removal equipment that not less than 85% dust removing efficiency must be installed in the front of induced draught fan, in order to reduce the fume content into the fan and minimize dust abrading on fan, and improving the service life of fan.

3.There are many series of industrial boiler at present. The burning coal in high and low grade is vast difference. The resistance of dust removing unit and coal saving unit is not uniform. There are great different between the flow rate and pressure of induced draught fan. Take into account the economics and suitability of the fan, provide Type Y8−39 and Y9−38 two series of fan for users to select. Connection and installation dimension of two series fan with the same model is the same.

Performance and selection:
Performance parameter in performance table of the boiler flue dilution fan is converted with non-dimensional performance table"table 1" "table 2".
The converting result is correct when Re≥5×106, and when Re≤5×106, the relative correction is performed on each fan №. according to test results. Its value takes performance table as a standard.

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The dimensional performance curve is converted with non-dimensional performance curve. The converting formula is as follows:

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1.Designer and user select induced drought fan №. in performance table according to the required flow rate and total pressure. The specific performance and the complete motor must be found out from table, but power and speed should be matched and note it when purchasing.  

2.The performance of each speed in performance table is that the performance in the range of 90% maximum efficiency is divided into 7 performance points according to flow rate. Take performance table as a standard when purchasing. 

3.The performance of fan ex-works is that the value of total pressure under the given flow rate shall not exceed ±5%.

4.№4~№6.3 in Performance table is calculated with fume gas atmospheric temperature t=220℃、200℃, atmospheric pressure P=101325Pa, air density ρ=0.713, 0.745kg/m3, above №7.1 is calculated with fume gas atmospheric temperature t=200℃、175℃, atmospheric pressure P=101325Pa, air density ρ=0.745, 0.784kg/m3. The selecting curve and performance table of fan with damper indicate the parameter when the damper is full open(0℃).

5.When the operation condition is non-standard, the performance is calculated with following formula:

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6.The required power in the table of performance and optional part:

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7.There are the following relation ship among Q(flow rate), P(total pressure), N(power ) and n(speed)when the inlet condition is not changed.

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From the formula of item 5 total pressure and item 6 required power formula N,warn us that when motor capacity is not changed,prohibit the fan in cold and full speed running or arbitrarily increasing speed,otherwise there are danger of burn-out on motor due to overload. 

8. Treatment of excessive or insufficient flow rate: 
The phenomenon of flow excess or insufficient often occurs when use, there are many reasons of occurring such phenomenon. If the phenomenon of flow some times large and sometimes small occurs during operation, or suddenly reduced within short time, the main reason is that the pipe net is plugged. The phenomenon of flow excess or insufficient will occur during normal running, the main reasons are as follows:
(1) The actual and calculated values of pipe net resistance is widely different. The normal pipe net characteristic equation: P=kQ2, Where: k―the coefficient of resistance, if the actual value k is less than the calculated value k ,the flow rate increases; vice versa, flow rate decreases, see fig.2 right.
(2) The effect of fan total pressure deviation △P have not been considered during selecting, when the actual total pressure of fan is positive deviation, the flow rate increases, and when it is negative deviation, the flow rate decreases, see fig.2 left.

The flow rate excess or insufficient occurred during fan operating can be adjusted by damper or gate. When the damper is full open, the flow rate is still insufficient, one of the following methods can be used to eliminate:
1. Change pipe net to reduce the coefficient K of resistance.
2. Increase fan speed,but it should not be more than that max. speed of the type given in the performance table.

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