Constant flow square cooling tower

Constant flow square cooling tower, cross flow induced draft cooling tower

Cooling water enters from the top and flows through the packing layer; Air enters from one or both sides, inducing the fan to make the air flow laterally through the packing layer.

Due to the natural flow distribution system of hot water in this type of cooling tower:

Advantages of constant flow square cooling tower:

Low water pump pressure head

Lower initial investment for water pumps,Lower annual operating energy consumption and costs,When the flow rate changes significantly, it will not have adverse effects on the water distribution system.

inferiority:

Low pressure head can cause the nozzle to easily clog and the cooling water to not disperse well into fine water mist when sprayed,Direct exposure of a hot water tank to the air can lead to the growth of algae

The area occupied is relatively large because the pressurized water distribution spray device in this type of cooling tower:

Advantages:

By increasing the height of the tower, a longer heat transfer process and smaller cooling amplitude can be achieved. Due to the fact that the pressurized spray device can spray smaller water droplets, the heat transfer efficiency is higher.

inferiority:

The pressure head of the system water pump has increased

Increased energy demand leads to increased operating costs

The cooling water nozzle is difficult to maintain and clean

We need a water distribution system and related pipelines, so the initial investment has increased.

Operating parameters and selection design of cooling tower

1.Cooling water temperature difference: inlet temperature - outlet temperature

large temperature difference=high-performance

2.Cooling amplitude: The difference between the outlet water temperature of the cooling tower and the inlet air wet bulb temperature:

Small cold amplitude=high-performance

3. Efficiency:

4. Cooling tower capacity

The capacity unit of the cooling tower isKilocalories per hour "or" cold tons ";

Cooling tower capacity=Cooling water mass flow rate x specific heat capacity of water x temperature difference;

high-capacity=high-performance

5.Calculation of supply water volume

Evaporation loss of water（E）

E = Q/600 =（T1-T2）*L /600

ERepresenting the amount of evaporated water(kg/h)；

QRepresenting heat load(Kcal/h)；

600Representing the latent heat of evaporation of water(Kcal/h)；

T1Representing the inlet water temperature(℃)；

T2Representing the outlet water temperature(℃)；

LRepresenting the circulating water volume(kg/h).

Calculation of supply water volume

Splashing loss of water volume（C）

The splash loss of a cooling tower is determined by factors such as the design type of the cooling tower and wind speed. Under normal circumstances, its value is approximately equal to the circulating water volume0.1~0.2%about.

Regular discharge water loss（D）

The loss of regularly discharged water quantity depends on factors such as water quality or solid concentration in the water. Generally, it is about the amount of circulating water0.3%about.

M=E+C+D

Evaporation loss of water（E）； Splashing loss of water volume（C）； Regular discharge water loss（D）.

When a cooling tower is used for air conditioning, the temperature difference is designed to5At this temperature, the required supply water for the cooling tower is approximately equal to the circulating water volume2%about.

6.Cooling water flow rate

K·Q=C·M·ΔT

K:Estimation coefficient

Q:unitZHigh cooling capacity

C:specific heat capacity of water

ΔT:temperature difference between supply and return water

M:Cooling water quality flow rate

compression type refrigerating unitZHigh cooling capacity1.3Double;

The cooling capacity of absorption refrigeration units (lithium bromide)2.5Twice.

Example of Selection

Example: Use one machine for each task640RTThe engineering cooling tower water flow rate and makeup water volume of the unit.

Q=640RT=2251KW

K=1.3

C=4.2KJ/(kg·℃)

ΔT=5℃

Water replenishment amountm=M·2％=140kg/s·2％=2.8kg/s