1. Preface

Coal fired boilers generate a large amount of black smoke during operation, which is emitted into the atmosphere through large chimneys, seriously polluting the boiler and surrounding plant environment, and more importantly, directly endangering the natural environment and human health. In order to improve the environmental conditions of the job and solve the problem of boiler pollution to nature, our company organized dust removal technicians to conduct research and investigation on the pollution status of the boiler. The concentration and temperature of smoke and dust produced during the combustion process of coal in boilers. Our company's dust removal theory and experience in production equipment have led to effective measures being taken for the dust removal and purification system of boilers.

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Boiler parameters:

(1) Capacity:20t/n.

(2) Smoke volume:3000 m³/n.

(3) Temperature: Provincial gas outlet140^..

(4) Smoke concentration:30g/m³.

3、120T tons of coal-fired powerBoiler bag filterDesign of smoke capture hood

Connect the pipeline from the outlet of the economizer to the inlet of the dust collector, connect the outlet of the dust collector to the inlet of the fan, and send the fan outlet to the flue, which is then discharged into the atmosphere through a large chimney.

3．2Flue Gas Cleaning

The purification of flue gas can only be achieved by dust collectors. The quality of dust collector selection directly affects the collection effect, power consumption, and long-term stable and reliable operation of the entire dust removal system. There are various forms of dust collectors, each with its own advantages and disadvantages. The key lies in how to leverage strengths and avoid weaknesses, and adapt to the system process and dust composition to achieve optimal results. For boiler flue gas, bag filter is more suitable. It has a significant effect in removing black floating dust, and the emission concentration can be controlled within50mg/Nm³Below. Based on the location of the boiler, which has a lower temperature in winter and is prone to condensation, our company adopts a new type of boiler specific "anti condensation" bag filter. Many bag filters in various industries in China were initially used well and the system was functioning normally. But after a period of use, the resistance of the dust collector increases, the system air volume immediately decreases, and the capture effect deteriorates, ultimately leading to a significant difference between the actual effect of the dust removal system and the design specifications or the effect during the initial operation stage, and requiring modification. Long term boiler dust removal practice tells us that "simple, practical, reliable, and economical" dust collectors are popular among enterprises.

3．3The characteristics of the "anti condensation" dust collector used in this scheme

Large settling chamber reduces the structural resistance of the dust collector.

Choosing a reasonable filtering wind speed is one of the important parameters for determining the structure of a dust collector, and its impact is crucial. In the application of similar dust collectors in China, there is a one-sided pursuit of low investment and land saving, while blindly copying foreign process experience and choosing up to2.0~2.5m/minThe filtration wind speed does not consider the application and working point of domestic filter media, resulting in a sharp decrease in the service life of filter bags and the emergence of "high resistance". The system air volume rapidly decreases in the short term, leading to increased operating costs and failure to achieve dust removal effects.

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bag Number:240strip

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bag Long:6m

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Filter bag material: Flumes needle punched felt

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Resistance power:1200pa

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effect Rate:99.5％

（1）20T ton coal-fired boiler bag filterHZFCThe Type II rotary back blowing flat bag dust collector uses industrial polyester needle punched felt as the filter bag, which is suitable for high temperatures and has strong hydrophobicity. Practice over the years has proven that this dust collector has a purification rate of up to（99.5%）The above structure is compact, occupies a small area, fully utilizes space, operates reliably, is easy to maintain, and is durable. The filter bag has a long service life and can handle dusty hot gas temperatures up to220Advantages such as around ℃. Suitable for the process recovery and dust removal purification of fine dust, the results of environmental protection departments in several regions of our province have proven that the emission concentration can be much lower than the specified standard. Widely used in metallurgy, casting, mining, chemical industry, refractory materials, cement building materials, grain processing and other sectors.

The dusty airflow enters the upper space of the filter chamber tangentially from the air inlet. Under the action of centrifugal force and gravity, major dust particles swirl along the wall of the filter chamber and fall into the ash hopper, while minor dust particles are forcibly retained and adhered to the outer wall of the filter bag by the filter bag; Under the pressure difference between the inside and outside, purified air passes through the filter bag and enters the clean room through the trapezoidal hole of the flower plate, and is discharged into the atmosphere. As the dust accumulates on the filter bag, the amount of dust gradually increases. When the dust reaches the cleaning level, a timed cleaning device is used to control it, automatically starting the anti blowing machine and the anti blowing rotary arm rotation mechanism for cleaning. Blow off the dust adhering to the outer wall of the filter bag into the ash hopper. When the dust is completely reduced, the reverse blower and the reverse blowing rotary arm transmission mechanism automatically stop working.

Compared with the commonly used pulse bag dust collector in China, the rotary back blowing flat bag dust collector has the following characteristics:

1）The shell is designed as a cyclone dust collector volute inlet, which can play a local cyclone role and reduce the load on the filter bag. The shape of the cylindrical dome is uniformly stressed and has good anti explosion performance.

2）The high-pressure fan equipped with the equipment is used for reverse blowing and dust cleaning, which is not limited by the gas assisted conditions of the usage site. It has fewer vulnerable parts, easy maintenance, reliable operation, and overcomes the disadvantages of compressed air pulse dust cleaning. The reverse blowing distance is large, and a long filter bag can be used to fully utilize the space, occupying a small floor area.

3）The trapezoidal flat bag is arranged inside the cylinder, with a simple and compact structure. The filtering area refers to the elevation. Under the action of reverse air blowing, the amplitude of the trapezoidal flat bag is large, and only one vibration is needed to shake off the accumulated dust, which is conducive to improving the service life of the filter bag.

4）The normal service life of the filter bag should not be less than one year. The efficiency of the dust collector can reach99.5%.