The 30,000m3/h cross-flow dry-wet cooling tower in Ishikawa Island was introduced to China in the late 1970s with the anniversary of the Ethylene Joint Chemical Plant. Daqing area is located at 45 5 ′ ~ 47 north latitude, with an annual average temperature of 3.3℃ and a freezing period of more than 5 months. Bad weather conditions bring difficulties to the operation of cooling towers in winter. Although the design of heavy-duty cooling tower in Ishikawa Island considered the anti-icing problem, the operation practice proved that the icing problem still existed. According to the present situation of cooling tower, Cangzhou Chemical Cooling Tower Packaging Factory of China Chemical Co., Ltd., combined with the old tower reconstruction experience and anti-icing technology accumulated by the factory for many years, put forward a new anti-icing technical transformation scheme for cooling tower. After implementation, the anti-icing effect is obvious after running in winter of 2003-2005.
1, cooling tower status
The circulating water cooling tower in the water and gas plant of Niannian Petrochemical Company is a fog-limited cross-flow dry and wet cooling tower, which is divided into two types, one with five rooms and the other with ten rooms. The plane dimensions are: 64.05m×20. 13m, and the tower height 14.662m (excluding the height of the air duct at the upper edge of the sink). The tower is a wooden structure and has been treated with CCA. Water filler adopts filler mixing technology, and is equipped with high-efficiency film filler and arch-drop filler. The assembly principle is: a vertical wave frame membrane combined packing is arranged on the edge layer near the louver, the diameter depth of single membrane filler is 0.9 15m, and the other diameters are all provided with arch fillers. The water receiver adopts multi-wave dual-function water receiver, and a dense water receiver with high water collection efficiency and slightly large wind resistance is arranged at the upper part of the tower, and a sparse water receiver with small wind resistance is arranged.
2, the technical scheme of transformation
The cooling tower of the first circulating water field is a dry-wet cross-flow wooden cooling tower. In winter, the cooling tower freezes seriously, which seriously damages the tower structure, shutters and side fillers. A lot of money and manpower are needed to repair and maintain the cooling tower every year. One of the main maintenance measures is to use forced fan reversal to solve the problem of icing in winter. Although the deicing effect is good, it also pays the price of accelerated damage of fan components.
In order to completely solve the serious problem of cooling tower freezing in winter, after the research of relevant departments and the approval of the company's science and technology department, on August 24th, 2003, a plastic spray pipe of ∮60×3.5UPVC was installed on the top of the louver on the 6th floor of Tower 1-6, and the outlet water of ∮7mm was treated every 50mm on the spray pipe.
3. Reconstruction, construction and operation
The design and construction tasks are all completed by Cangzhou Chemical Cooling Tower Packaging Factory. Construction started on August 24th, 2003, and all deicing pipelines were installed on October 23rd, 2003. Due to financial problems, there is no deicing pipeline installed on the upper 8 floors. By the end of February, 2004, the total running time was 2352 hours, and the process parameters of the whole tower met the design requirements, and the following results were achieved.
After the deicing pipe is installed, the average temperature difference of circulating water level increases. The average temperature difference of water supply this year is 8.35℃, which is 4.63℃ higher than the same period last year. This shows that the efficiency of air circulation and cooling is significantly improved, and the macro-control ability of circulating water temperature is enhanced. From the outside of the cooling tower, the freezing condition of the cooling tower in winter has been fundamentally improved, and the shutters are basically not frozen, which meets the design requirements of the deicing pipe.
After the deicing pipe is installed, the louver basically does not freeze, so the East Tower fan does not reverse in winter, saving electricity and meeting the engineering requirements. Compared with the same period in 2002, the energy saving is:180 kw×10h×100 days× 5× 85% = 765,000 kw h, (Note: power saving = power of one fan× number of reversal days in the same period in 2002× power of fans.
Because the fan does not reverse in winter, the negative impact of reverse rotation on fan parts is reduced, thus reducing the damage frequency of fan blade rings, gears and other parts and prolonging the service life of fan parts. According to the statistics of the average number of failures caused by fan reversal in the past, the ice melting pipe can avoid the blade ring damage and gear failure of CT-00 1 tower fan twice a year, which is more economical than that in 2002.
When the fan rotates reversely in winter, due to the increase of steam pressure, the circulating water entrained by hot and humid steam accelerates to drift outward. After the deicing pipe is put into use, the drift is reduced, the influence of drift on the surrounding environment of the cooling tower is controlled, and the icing degree outside the tower and the corrosion to outdoor equipment are reduced. At the same time, the overall appearance of the cooling tower has also been greatly improved due to the reduction of the icing amount of the tower, which laid the foundation for the on-site environmental remediation work this year.
The use of deicing pipes basically eliminates the potential safety hazards of large ice cubes formed on the cooling tower in winter to personnel and production, improves the safety factor of cooling tower operation, and makes the operation of cooling tower and staff inspection safer and more reliable, with obvious indirect benefits.
4. Conclusion
To sum up, the effect of deicing tube is obvious. Its application has basically solved the serious problem of freezing of unique cooling tower in northern winter, improved the reliability of its own operation, improved the operating conditions of the cooling tower, reduced the loss of fan parts, prolonged the service life of the fan, and made the cooling tower run more safely and stably.
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