Reverse-flow Cooling tower
Reverse-flow Cooling towerDesign, it is necessary to understand a certain known countercurrent cooling tower, that is, the ruler of the known cooling tower, the thermal resistance performance of the filler, the first case of the fan to calculate the water temperature of the tower. In another case, the design of a countercurrent cooling tower is required based on known cooling tasks, namely the amount of cooling water, the water temperature in and out of the tower, the dry, wet bulb temperature (or dry ball temperature and relative humidity) and atmospheric pressure of the inlet tower Air.
The calculation steps for the countercurrent cooling tower are as follows:
(1) According to the given amount of water, the ventilation capacity of the countercurrent cooling tower can be calculated, and the cooling number of the tower can be determined according to the thermal characteristic curve of the filler selected by the cooling tower.
(2) With the same gas-water ratio, given different tower water temperature, inlet water temperature (for the tower water temperature plus cooling in and out of the tower water temperature difference), according to the formula (3,196) to calculate the cooling number, the calculated cooling number by formula (3-74) correction to the filler thermal characteristics data when the inlet water temperature.
(3) The difference between the water temperature of the different towers and the number of cooling towers and the water temperature of the tower should be mapped into curves.
(4) The point at which the curve intersects with the cooling number of the tower, that is, the operating water temperature of the cooling tower.
The calculation steps for the second case are as follows
(1) First determine the size of the countercurrent cooling tower, the size of the determination should be based on the existing experience or design norms as the guiding principle, the initial determination of the plane size of the cooling tower, the water density of the tower should not be greater than 16t/(H ㎡)
(2) Select the form and height of the water filler. For countercurrent cooling towers, the general filler height can be slightly higher, which can reduce the size of the cooling tower, for the often used film water filler, the desirable height of 1.5m, drip filler should be higher.
3) According to the plane size of the cooling tower, determine the vertical surface size and the diameter of the fan, the determination of the fan diameter should be consistent with the fan supply model, that is, reference fan production plant fan samples.
(4) on the basis of the preliminary determination of the above conditions, it is assumed that a wind volume according to the total resistance of the tower calculation, according to the total resistance that is the fan full pressure, check the performance of the fan curve, determine the new fan air volume, and then calculate the total resistance of the tower, until the fan's full pressure and tower resistance is equal When calculating the air volume, the density of different parts of the air can be calculated according to the average density of air in and out of the tower, and the outlet air temperature is desirable to the average of the water temperature of the
(5) Given the different angle of fan blade, the relationship graph between fan blade angle and fan air volume can be calculated by repeating step (4).
(6) Given the different air volume, that is, given the different gas-water ratio, the relationship curve between the cooling number of the cooling task and the gas-water ratio can be calculated by formula (3-96), and the intersection point with the filler characteristic curve is found, that is, the working points are obtained.
(7) According to the air volume required by the work point, from which the fan blade mounting angle can be found, from the fan characteristic curve to further check the shaft power of the fan, determine the model of the supporting motor.
(8) At this point, the basic design of a countercurrent cooling tower is complete. According to the size of the wind tower body, the height of the filling and so on for local word finishing, and then repeat the steps (1) ~ (5), the synthesis of various due to the optimization, to achieve economic purposes.