Cooling Tower - The Generation and Hazards of Freezing in Co

Generation and harm of freezing of cooling tower-cooling equipment

 

When the cooling tower runs in winter in cold and severe cold areas, the temperature of circulating water is much lower than that in summer. Due to the influence of low temperature air, the equipment and foundation of Lingleng system may be frozen during operation and stop operation. The common parts are as follows

 

1. Watering filler

 

When the drenching density of the outermost packing is generally low, cold air will invade people first, which is the most likely to cause freezing damage. When the drenching packing is in other areas with low drenching density, such as blocked and damaged water tanks, blocked nozzles, falling off or misalignment of splash plates, it is also easy to cause local freezing damage.

 

2. Pillars and supports of watering device

 

When the cooling tower is shut down in winter, the columns of the water spraying device are located in the water level fluctuation area and the infiltration area, which are prone to freeze-thaw damage with the change of air temperature and water temperature. The outer ring column and support are the easiest to hang ice.

 

3. Rigid ring of inclined pillar and column top

 

When the water-retaining eave (or wall chute) on the inner wall of the ventilation tube is damaged, the condensed water and splashing water on the inner wall of the cooling tower can flow downstream, thus freezing on the ring bottom and inclined pillars.

 

4. No-flow circulating water protection structure

 

When the cooling tower is shut down in winter, the water-filled circulating ditch, penstock, sluice gate, sluice well, etc. freeze because the water does not flow and cannot supplement heat, and the lateral frost heaving force generated by the freezing can reach 0.2-0.3 MPa, which damages the structure. The bottom plate, side wall and bottom plate of the water-collecting basin without water filling protection are also easily damaged by soil frost heave when the soil moisture content is high.

 

The hazards caused by freezing of cooling water system are:

 

1. The watering device is greatly overloaded, and the watering filler and its supporting beam collapse, even leading to partial or whole collapse,

 

2. Freeze-thaw cycles are repeated on the coagulation of the water spraying device, inclined pillar and ventilation tube, which accelerates the destruction of the durability of the material and reduces the service life of the structure.

 

3. The freezing and expansion of water can produce frost heaving force, which can directly burst pipelines, ditches, gates and other equipment, and the frost heaving of soil can directly burst the bottom plate of the water collection tank, the side wall and bottom plate of the circulating ditch, etc.

 

Insufficient attention and measures to prevent freezing damage of cooling equipment, especially in winter, can seriously affect the operation efficiency, service life and maintenance cost of equipment. There are many practical experiences and lessons in this respect. A hyperbolic cooling tower in a power plant in Heilongjiang Province has a water spraying area of 750 square meters and is filled with cement grid.

 

In the year when it was put into operation, the lower the cooling water temperature was, the better the efficiency of the steam conveyor was. In the severe winter season, the cooling tower was frequently started and stopped, resulting in the freezing of the tower core and forced to stop. After thawing in spring, it was found that the drenching packing was crashed by 30%. Since then, we have learned a lesson and paid attention to the winter operation mode. After the repair, there has been no freezing and crash of the shower plate for many years. A hyperbolic cooling tower in a power plant in Heilongjiang province has a water spraying area of 2000 square meters, and its inlet pipeline valve is an electric valve in the cooling tower group of the plant, which is convenient to start and stop.

 

Because the tower was mistakenly started or stopped frequently in winter, it was used as "peak shaving". The reinforced concrete components such as beams, columns and water distribution tanks of the watering device were quickly and gradually destroyed due to freeze-thaw cycles. After two years of use, the concrete became brittle and peeled off. After many repairs, it had to be demolished and rebuilt a few years later, costing hundreds of thousands of yuan. Due to improper operation measures in winter, the tower's overhaul period is short, the overhaul cost is high, the operating efficiency is low with illness, and the shutdown during the maintenance period also has a great impact on production.