1. Overview

Low pressure long bag pulse technology has developed rapidly in China's cement industry in recent years. It combines the advantages of anti blowing bag dust collectors, air box pulse dust collectors, and jet pulse dust collectors, overcomes their shortcomings, and becomes a new generation of pulse dust collector technology.

On the basis of introducing anti blowing bag dust collectors, air box pulse dust collectors, and jet pulse dust collectors, our company has developed a low-pressure long bag pulse dust collector LLPC (Low press Long bags Pulse Collector) dust collector with our own characteristics, referring to the long bag pulse dust collector technology at home and abroad. The filter bag of the dust collector is 6m long, which makes the dust collector occupy a small area. The pulse valve adopts a submerged type, which requires low pressure (0.3Mpa) for dust cleaning, consumes less energy, and has the same dust cleaning effect as the pneumatic pulse dust collector. Low pressure long bag pulse dust collectors are the best choice for dust removal equipment when dealing with high air volume dust points.

The mandatory standard recently implemented by the country, the "Emission Standards for Air Pollutants in the Cement Industry," has put forward stricter requirements for pollutants from the cement industry. According to the requirements of the new standard, the dust removal device should operate synchronously with its corresponding production process equipment, with an annual synchronous operation rate of not less than 99%, and dust removal devices that are shut down due to process fluctuations should not be used. In this way, if the main emission points of cement plants such as kiln tail and kiln head continue to use electrostatic precipitators as dust removal devices, it is difficult to meet such strict emission requirements and operating standards. With the continuous introduction of new production processes and equipment, the LLPC high-temperature and low-pressure long bag pulse bag dust collector has become the preferred dust removal equipment for cement industry production lines due to its high dust removal efficiency and low operational failures.

In recent years, due to the continuous advancement of science and technology, the variety of filter materials used in bag filters has become increasingly diverse, and their quality and performance have also improved. For low-pressure long bag pulse dust collectors, glass fiber coated filter media has emerged, which provides a good choice for processing high-temperature dusty gases in low-pressure long bag pulse dust collectors. Glass fiber membrane filter material is a new type of filter material made by coating multi porous polytetrafluoroethylene film on a glass fiber base cloth treated with a special surface treatment formula. It combines the advantages of high strength, low elongation, high temperature resistance, corrosion resistance of glass fiber with the excellent properties of smooth surface, hydrophobicity, breathability, and good chemical stability of polytetrafluoroethylene multi porous film. It can almost intercept all the dust in the dusty airflow and ensure the maximum flux of the airflow without increasing the operating resistance, making it an ideal flue gas filtration material. Due to the fact that glass fiber membrane filter material allows for a 50-70% higher net filtration air ratio than ordinary glass fiber filter material, it can be applied to LLPC dust collectors for high-temperature dust removal.

The high-temperature LLPC dust collector can operate efficiently for a long time under high dust content flue gas conditions below 260 ℃~280 ℃, with a stable dust collection efficiency of over 99.9%. It has two forms of positive and negative pressure and is equipped with an automatic control device. It can be fixed resistance or timed, and can be maintained without affecting production without stopping the whole machine.

The LLPC dust collector consists of a shell, ash hopper, filter bag, bag cage, pulse valve, spray pipe, lift valve, intake manifold, exhaust manifold, ash discharge valve, etc. Its working principle is shown in the above figure.

When the dusty gas enters the dust collector from the air inlet, it first encounters the inclined partition in the middle of the air inlet and outlet, and the airflow turns to flow into the ash hopper. At the same time, the airflow speed slows down. Due to inertia, the coarse particles of dust in the gas directly fall into the ash hopper, playing a role in pre dust collection. The airflow entering the ash hopper then turns upward and passes through the filter bag with a metal frame inside. The dust is captured on the outer surface of the filter bag, and the purified gas enters the clean air chamber at the upper part of the filter bag chamber. It is collected through the lift valve and discharged through the outlet duct. The shell is divided into several independent dust collection chambers by partitions, and each dust collection chamber is cleaned at a fixed time or with a fixed resistance. Scheduled dust cleaning refers to taking turns cleaning each dust collection room at given intervals.

Fixed resistance dust cleaning is a process in which a differential pressure gauge is installed in the system to clean a certain chamber when the system pressure difference reaches the limit value. Each room is equipped with a lift valve, which is closed during dust cleaning. When cleaning, the pulse valve is opened, and compressed air enters the filter bag through the pulse valve and spray pipe, causing the filter bag to expand, vibrate, and achieve the purpose of cleaning. When cleaning a room, the PC controls the cleaning of each group one by one. The cleaning cycle of the pulse blowing width of each dust collection room and indoor group is automatically and continuously controlled by a PC.

The characteristic of this dust collector is to use compartments and groups to clean dust alternately, which is called offline cleaning. When a certain filling is carried out for blowing and cleaning, the lifting valve of the chamber is closed, and the filtered airflow is cut off, avoiding the secondary flying of dust generated by blowing and cleaning. So this dust collector can capture gases with a dust concentration of up to 1000g/m.

3、 Main technical performance

When using glass fiber coated filter cloth, its machine performance and technical parameters are as follows: