Ideal Inline Duct Boiler Chimney forced Draft Fan Assembly G4-68 Y4-68 Series

GY4-68 Forced and induced drought fan for boiler is a series product design jointly by fan industry in 1982, typically used for ventilation and drought system of boiler with evaporation capacity of 230t/h and less in thermal power plant.
Product description

PURPOSE
GY4-68 Forced and induced drought fan for boiler is a series product design jointly by fan industry in 1982, typically used for ventilation and drought system of boiler with evaporation capacity of 230t/h and less in thermal power plant. In the case of performance that is close to and without special requirements, G4-68 can be also used for mine ventilation and general ventilation, two types of fans have such advantages as high efficiency, low noise and high strength.
The medium which is handled by fan is air,the maximum temperature shall normally not exceed 80℃;the medium handled by induced draft fan is flue gas,the maximum temperature shall normally not exceed 250℃.The dust control unit must be added  in the front of induced draft fan in order to reduce the dust content of flue gas entered the fan,the efficiency of the added dust remover is not less than 85%.


TYPE
The fan is made as a single suction .There are 7 types of fan numbers which are №8、 №9、 №10、 №11.2、 №12.5、 №14 and 16.
The fan can be made of 2 types of rotation i.e, right and left. Viewing from one end of the motor,it is called as clock-wise fan if the impeller rotates clock-wise,symbolized with"right", On the contrary, it is called as counter-clock-wise fan if the impeller rotates counter-clockwise, symbolized with "left".
The outlet position of the fan can be expressed from the outlet angle of the casing. It can be made 6 kinds of angles which are 0°,45°,90°, 135°,180°,225°,from both"Right"and"left".
The driving mode of the fan takes mode D,the connection of flexible coupling is used.


STRUCTURE
The fan mainly consists of impeller,casing,inlet,damper and driving unit.
Impeller — It is made of twelve back tilt wing vanes welded between arcing conical wheel cover and flat wheel disc. Generally, impeller of the fan is 16Mn, connection where the vane to wheel cover is lined with antiwear backplate, vane head is a solid body and build-up welding is increased at the place where is easily worn as a result the service life of the vane is improved, and the fan is different from it, impeller is calibrated by static and dynamic balance and over-speed operation experiment, therefore the operation is smooth and reliable.

Casing — Volute is welded by general steel sheet. The enclosure of single suction fan is made to two different types: enclosure of №8~№12.5 is made to integral structure. A quarter of №14、№16 enclosure

Is removable. For drought fan, scroll plate on which an ash discharge gate is opened and thickened as appropriate to prevent smoke ash abrasion.
Inlet — To be integrated into a convergent streamlined structure and bolted on the suction side of the casing. 

Damper — Used to regulate flow of the fan. №8、№12.5 is composed of eleven petal vanes and №14、№16 is composed of thirteen petal vanes, which are installed axially in front of air inlet, because of externla drive structure to be used, so the running is agile and expedient. Regulating range is from 900 (full closing) to 00(full opening). Handle position of the regulating gate is at right side looking from air inlet. For right-hand fan, the handle is from full closing to full opening by pushing from lower to upper. For left-hand fan. Handle is from full closing to full opening by pulling from upper to lower. To make all parts of regulating gate mnormal operation, attention to lubrication must be paid. For the regulating gate of the fan, calcium-sodium-base grease is used for lubrication; for drought fan, because of high ait temperature, molybdenum disulfide high temperature (260℃) grease must be used for lubrication.

Driving unit — consists of main shaft, bearing box. Main shaft is made from high quality steel, with rolling bearing and water cooling integral bearing box, therefore, water supply pipe must be additionally installed, water consumption is varies with ambient temperature, generally consider by 0.5~1m3/h. bearing box is provided with thermometer and oil level indicator, luboil is 30# machine oil, oil filling capacity is carried out acc. to oil level mark.


PERFORMANCE AND SELECTION
Optional performance of this fan should be calculated in accordance with non-dimensional characteristic curve chart and non-dimensional performance table.


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

11.jpg


Where

U—  Line speed of outside end of impeller blade   (m/s);

D—  Diameter of outside end of impeller blade   (m)
ρ —  Suction density   (kg/m3)


22(001).jpg

G4−68(left fig.) and Y4−68 (right fig.) centrifugal fan for boiler nondimensional characteristic curve chart.


G4-68 centrifugal fan for boiler nondimensional performance table

Operating condition point/
Code

1

2

3

4

5

6

7

Flow coefficient 111.jpg

Full pressure coefficient 222.jpg

Full pressure efficiency 22.33.jpg 
Internal power coefficient 333.jpg

0.155
0.493
0.858
0.0891

0.175
0.483
0.887
0.0953

0.195
0.467
0.909
0.100

0.215
0.445
0.915
0.105

0.235
0.415
0.904
0.108

0.255
0.377
0.880
0.109

0.275
0.335
0.843
0.109


Y4-68 induced drought centrifugal fan for boiler non dimensional performance table

Operating condition point/
Code

1

2

3

4

5

6

7

Flow coefficient 111.jpg

Full pressure coefficient 222.jpg

Full pressure efficiency 22.33.jpg

Internal power coefficient 333.jpg

0.145
0.492
0.836
0.0853

0.165
0.483
0.870
0.0916

0.185
0.465
0.892
0.0964

0.205
0.443
0.900
0.101

0.225
0.415
0.893
0.105

0.245
0.380
0.865
0.108

0.265
0.338
0.822
0.109

When fig. and table above are only applicable for Re≥5×106, at Re<5×106, corresponding modification is carried out acc. to experiment result

33.jpg

Where:
Re  —  Reynolds number
D2  —  Diameter of outside end of impeller blade   (m)
u2  —  Line speed of outside end of impeller blade   (m/s)
γ  —  Coefficient of kinematic viscosity(0.15×10-4)  (m2/s)


Notices in selection of this type of fan:
1. Fan No. is selected by engineering design and user based on the flow and full pressure. Specific performance and motor used should be found in "performance and  optional parts table", other model of motor may be selected also, but power and speed should be appropriate and indicate on ordering.

 
2. Each rev performance of "performance and optional part table" is to divide the performance within range of the max efficiency 90% equally to seven calculated performance points acc. to flow, it will take performance table as prevailing on ordering.


3. The qualified product performance of fan as delivery is that full pressure is not more than ±8% at rated flow.


4. In performance characteristic curve chart and optional table:
Performance of the ventilation fan is calculated acc. to air media of t=20℃, atmospheric pressure Pa=101325Pa and air density γ= 1.2 kg/m3.The standard state of induced draft fan indicates atmospheric pressure Pa=101325Pa,atmospheric temperature t=140℃,air density ρ=0.85kg/m3.Performance curve and table means the parameters as regulating gate is fully opening (0°).


5. If the operation condition of fan shall not meet that of item 4,the performance is calculated with the formula below:

44.jpg


Where:
P、Q、N — Manes the full pressure, flow and shaft power within performance table.
P1、Q1、N1 — Full pressure, flow and shaft power of the fan at service condition.
B — Atmospheric pressure (Pa) at service place.
t1 — Temperature of delivery air(℃).
t — Rated temperature in the performance table, ventilation fan t=20℃ and drought fan t=140℃.

 
6. In performance table:

55.jpg


Where: Q(m3/h), P(pa) and η are the flow, full pressure and full pressure efficiency of the fan respectively.
η1 —  Mechanical efficiency of the fan, coupling drive η1= 0.98.
K  —  Capacity reserve coefficient of motor, draught fan K=1.3 and ventilation fan K=1.15.
g  —  Gravity acceleration.
Motor power to be selected is generally not less than the power value required.


7. When air inlet condition is not changed, Q(flow), P(full pressure, N(power) and n (rev) have the following relation:

66.jpg


When capacity of motor does noty change, the draught fan can not be operated at full opening under cold state or rev is incresed at will, otherwise the motor takes the risk of overloading and being burnt out.

77(001).jpg

Relation of pipe grid performance and full pressure windage to flow


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:H=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 right.
(2) The effect of fan total pressure deviation H 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 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.
3. Select new fan with higher pressure.

 

PURCHASE INFORMATION
Fan No., rev, air quantity, air pressure, angle of air outlet, rotating direction, model of motor and power should be indicated in written on ordering
Note: Some manufacture has ever produced 13D and 22D fans, twelve fan Nos. of each.


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