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Shandong Fengxin Technology Development Co., Ltd

Mobile: + 86-15965759999

Tel.: + 86-0635-2531988

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Address: Hi tech Industrial Park, Linqing City, Shandong Province (shilitun, Xinhua office)


Relationship between exhaust air volume and semi open steam hood

2020-04-20 16:55:36
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Due to its unique advantages, the semi open steam hood of the drying section is widely used in the paper-making process of Yankee hood. Because the equipment of the drying section accounts for almost 40% of the investment in paper-making machinery, and it is also one of the processes that consumes the most energy in many processes, the design of the paper drying and ventilation system is very important. Excellent process design can prevent condensation, dripping, scaling and corrosion from forming in the steam hood of the drying cylinder, and the semi open steam hood can effectively improve the operating environment of the workshop, improve the quality of the paper web and the drying rate. Therefore, the design factors such as the drying rate and the amount of steam used for the semi open hood of the paper machine must be suitable for the exhaust air volume. If the exhaust air volume is too large, there will be water dripping on the four walls of the hood, which will cause paper defects, reduce the quality of finished products, and cause paper jam in the drying cylinder, etc.

Yankee hood manufacturer

For example: a 3200 / 160 multi net multi cylinder Kraft linerboard machine in a paper mill

Quantitative: 140-340g / m2;

Capacity: 80t / D;

Press section: one precompression + two ordinary presses. The drying section has three groups, 21 cylinders, 3000 large cylinders, 1500 cold cylinders, 1500 steam cylinders, 19 in total, and one half open hood.

During the operation of the paper machine, the exhaust air volume of the hood in the drying section of Yankee hood is too large, the negative pressure in the hood in the front drying section is too high, a large amount of cold air enters the hood, which causes the temperature of the exhaust air to decrease, the temperature of the air is lower than the dew point, and it is very easy to condense in winter and spring, which seriously affects the quality of the paper. In order to solve the problem of condensation and water dripping, the semi open hood exhaust system in the drying section is adopted.


Jinan Yankee hood

The production parameters are as follows:

The drying section is equipped with 5 exhaust fans, the exhaust air volume is 341580m3 / h, and the motor capacity is 133kw.

Paper machine capacity: 110t / D;

The test results of the paper web dryness in the drying cylinder are as follows: 39%, 64%, 70% and 90% respectively;

G=1000KW/(Gρ)

G = ventilation volume of drying section, m3 / h;

W = evaporation water quantity of drying section, kg / h;

K = air volume coefficient (1.1-1.4, which is closely related to the air permeability of the dry mesh and the structure of the hood);

G = water gas ratio, 25-40 ℃ (30-6040 ℃ in hot and hot areas);

ρ = air density, 1.29kg/m3


 

Jinan Yankee hood manufacturer


After calculation, it is known that the ventilation capacity of the drying section of the whole paper machine of Yankee hood manufacturer is 261116m3 / h, the exhaust air volume required for production is smaller than the actual exhaust air volume, and the design wind energy is larger. Therefore, one of the exhaust fans is removed and the hood is partially adjusted. After the transformation, the negative pressure of the front drying section is reduced, the exhaust temperature is increased, the water dripping phenomenon on the inner wall of the steam hood is eliminated, the paper quality is greatly improved, the paper jam problem of the large cylinder is completely solved, a large amount of electric energy is saved, the number of paper breaks is reduced, the operation is more convenient and fast, the operation efficiency of the paper machine is improved, and the production efficiency is greatly improved at the same time.

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丰信科技Email: fengxin@cnfengxin.cn
密闭气罩Address: Hi tech Industrial Park, Linqing City, Shandong Province (shilitun, Xinhua office)

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