1. Overview of Dust Collection Technology Development
The application and development of dust collection technology are closely related to my country's industrialization process. Dust collection technologies generally include mechanical dust collection, wet dust collection, electrostatic precipitators, and bag filters.
Mechanical dust collection utilizes gravity settling, inertia, or centrifugal force to separate dust particles. Its dust collection efficiency is generally below 90%, characterized by low efficiency, low resistance, and energy saving.
Wet dust collection utilizes the principle of gas-liquid contact washing to separate dust from the dust-laden gas into a liquid, thus removing dust from the gas. Its dust collection efficiency is slightly higher than mechanical dust collection, but it is prone to causing secondary pollution of the washing liquid.
Electrostatic precipitators pass dust-laden gas through a strong electric field, causing the dust particles to become charged. When the dust passes through the dust collection electrodes, positively/negatively charged particles are adsorbed by the negative/positive electrode plates, respectively, thereby removing dust from the gas. Electrostatic precipitators have high dust collection efficiency, but their efficiency is greatly affected by the resistivity of the dust, easily leading to unstable dust collection efficiency. Since the 1990s, electrostatic precipitators have been widely used in the treatment of flue gas pollution in thermal power plants, cement kilns, and other complex operating conditions characterized by high temperatures and large flue gas volumes. Baghouse dust collectors utilize fiber filter media to capture solid particles in dust-laden gas, forming a filter cake. This filter cake further filters out finer dust particles, achieving highly efficient dust removal. Baghouse dust collection technology can consistently achieve very high dust removal efficiency, with dust emissions below 5 mg/m³, and the efficiency is unaffected by dust characteristics such as resistivity. Generally, dust particles smaller than 10 micrometers (i.e., inhalable particles) have a greater impact on human health, and baghouse dust collectors have a high separation efficiency for inhalable particles. The application of baghouse dust collectors in treating ambient temperature flue gas (<120℃) pollution is gradually expanding. With the further development of high-temperature resistant filter media and pulse-jet cleaning technologies, baghouse dust collectors, due to their excellent dust removal performance, are increasingly widely used in the treatment of high-temperature, high-concentration flue gas.
With the acceleration of industrialization and urbanization, air pollution in my country has become increasingly serious, and emission standards for air pollutants have become increasingly stringent. High-efficiency electrostatic precipitators and bag filters have been widely used. Currently, electrostatic precipitators and bag filters are the mainstream dust removal technologies in my country.
Bag filters have greater advantages in energy conservation and emission reduction than electrostatic precipitators. Given the increasingly stringent national emission standards, the use of bag filters will become the main choice for controlling dust pollution.
2. Overview of the Dust Removal Equipment Industry Dust removal equipment is mainly used in industries with severe dust pollution, such as cement, steel, non-ferrous metals, power, machinery, chemicals, and waste incineration. The total output value of the dust removal equipment industry is closely related to the domestic and international economic development environment and the development status of downstream industries. In recent years, the total output value (sales revenue) of my country's dust removal equipment industry has fluctuated, increasing from 13.998 billion yuan in 2005 to 29.007 billion yuan in 2008, with an average annual compound growth rate of 27.49%. In 2009, affected by the international financial crisis, the growth rate of my country's cement, steel, non-ferrous metals, and machinery industries declined sharply, and the output value of some industries even experienced negative growth, resulting in a temporary slight decrease in the total output value of my country's dust removal equipment industry.