Environmental protection, as one of the most concerned topics at present, is an urgent matter from any point of view, whether it is large or small to the country or the citizens. In addition to strengthening their awareness of environmental protection, they should also use environmental protection equipment reasonably. In our daily life, the most common environmental protection equipment is divided into two kinds: sewage treatment equipment and waste gas treatment equipment. Although environmental protection equipment is widely used in many places, but many people ignore the development of environmental protection equipment itself and other important information, and precisely these information is very important... Classification of environmental protection equipment: In addition to the above mentioned sewage treatment equipment and waste gas treatment equipment, it also includes: 1. Solid waste treatment equipment: solid waste treatment equipment, the role of which is usually physical, chemical, biological, biochemical and biochemical methods to convert solid or waste into suitable transportation, storage, and so on. With the method of utilization or disposal, the goal of solid waste disposal is to make solid waste harmless, reduce and recycle. 2. Environmental monitoring equipment: for the purpose of environmental monitoring, according to the time and space designed in advance, collecting environmental information and data collection methods, observing, detecting and analyzing one or more environmental factors or environmental indicators intermittently or uninterruptedly. 3. air purification equipment: air purification equipment (also known as "air cleaner", "air freshener") refers to the product that can filter or purify air pollutants, is a product that purify air effectively and improve air cleanliness. Currently, indoor air purification equipment is the main and outdoor clean air dust is sprayed with environmental protection sprayer. Mainly. 4. Sewage treatment equipment: Sewage treatment equipment is an industrial equipment which can effectively treat domestic sewage and industrial wastewater produced in urban areas. It is of great significance to improve the ecological water environment and promote economic development to prevent sewage and pollutants from entering water directly by means of filtration or evaporation.

Bag dust collector has high dust removal efficiency and is inseparable from its dust removal mechanism. When the dust-containing gas enters the ash hopper through the air intake pipe at the lower part of the dust collector, due to the impact of the guide plate and the decrease of gas velocity, coarse dust will fall into the ash hopper, and the remaining fine dust will enter the filter bag chamber with the gas. Due to the inertia, diffusion, barrier, hook and static electricity of the filter material fibers and fabrics, the dust is stored in the filter bag, and the purified gas escapes from the bag and is discharged through the exhaust pipe. The dust deposited on the filter bag is removed by gas backwashing, and the dust is removed to the ash hopper through a double-deck dusting valve, and then discharged to the ash conveyor through the double-deck dusting valve. The dust deposited on the filter bag can also be removed by jet pulse airflow to achieve the purpose of dust removal, and the dust in the filter bag can be removed by the dust removal device. The high efficiency of bag filter can not be separated from the filter material. The performance and quality of filter materials are directly related to the performance and service life of bag filter. Filter material is the main material for making filter bags. Its performance and quality are the key to promote the technological progress of bag dust removal, and affect its application scope and service life.
The filter device consists of a bag filter and a granular layer filter. The former usually uses a bag made of organic or inorganic fibre fabric as the filter layer, while the latter uses particles of different sizes in the filter layer. Such as quartz sand, River sand, ceramsite, slag and other components. When the powder is repeatedly attached to the outer surface of the filter bag, the thickness of the powder layer increases and the resistance value of the bag filter increases. Pulse valve diaphragm gives instructions. When left and right pulse valves are opened, compressed air passes through high-pressure packaging. If there is no dust or small enough, mechanical cleaning will stop.
The gas purification mode of low-pressure pulse bag filter is external filter. Dusty gas enters each unit filter chamber from the guide tube. In the design, due to the sufficient vertical distance between the bottom of the filter bag and the upper part of the intake port, the reasonable air distribution can achieve uniform air distribution in the whole filter chamber through appropriate diversion and natural flow direction. The dust particles in the dusty gas are separated by natural sedimentation and fall directly into the ash hopper. The rest of the dust falls directly into the ash hopper under the guidance of the diversion system. As air flows into the middle chamber of the filter area, it is adsorbed on the outer surface of the filter bag. The filtered clean gas passes through the filter bag through the upper box, and the exhaust pipe discharges.
The filter bag is injected with compressed air, and the ash cleaning mechanism consists of an air bag, a nozzle and an electromagnetic pulse control valve. A nozzle is arranged at the top of the outlet of each row of filter bags in the filter chamber. The lower side of the nozzle is directly opposite to the center of the filter bag. Pulse valves are arranged on each nozzle to communicate with compressed air bags. When cleaning, the solenoid valve opens the pulse valve, and the compressed air is injected by the ash cleaning control device (pressure difference or timing, manual control), and the electromagnetic pulse injection is opened according to the set procedure. Compressed gas is introduced into the filter bag through the nozzle on the jet tube in a short time through the pulse valve, forming air wave, which makes the filter bag sink sharply from the bag mouth. Strong expansion and impact vibration, resulting in a strong dust removal effect, shake off the dust on the filter bag.

Due to the importance of environmental protection of the country and the people, bag filter is the first choice for collecting and controlling all kinds of dust and smoke. Bag dust collector is a kind of dust removal equipment which is widely used at present. It has been gradually upgraded from vibration and reverse blowing to pulse dust removal mode, which is the most widely used. Pulse dust removal is completed by compressed air and pulse valve. Reasonable setting of cleaning time of bag dust collector determines the dust removal effect of bag dust collector. So how long is the best time to set the time and cycle of ash removal? This cleaning time and cycle are set according to the nature of dust and dust concentration in the air inlet. There is no fixed standard, and it should be adjusted according to the effect of cleaning. For example, when the stone is broken, the cleaning time of the pulse valve is 15 - 18 seconds, and the pulse period is 5 - 10 minutes. When the coal-fired boiler is used, the pulse time is about 12 seconds, and the pulse period is 3-5 minutes. The working time of the pulse valve is 10 seconds and the pulse period is 5 minutes when it is used in woodworking factory.
Only when the time and cycle are set properly, the pulse valve can remove the dust more thoroughly on the cloth bag, and it does not waste the gas source. If not properly set up, there will be incomplete ash removal, large resistance of equipment, reduced air volume, reduced efficiency and so on. The dust removal time is short, the dust removal cycle is too long, and the dust on the filter bag can not be cleaned up, so the dust collector will be transferred to the filter state, which will make the operation resistance rise quickly. When adjusting the cleaning cycle, comprehensive consideration should be taken, such as common lime powder, in the case of high dust concentration. The interval of the pulse valve should be appropriately faster, generally about 30 seconds, and the weekly interval is about 5 minutes. The interval time of dust with larger adsorbability is slightly shorter. The adjustment of the interval time of the pulse valve should be decided according to the specific situation of the site and the characteristics of the dust. For the pulse bag filter, the time spent in the dust cleaning process (i.e. the time spent by the pulse valve injection) is the time spent in the dust cleaning process, which can be adjusted in the range of 0.05-0.5s. The interval between two cleaning cycles is usually 0-30 minutes. By adjusting the cleaning system of pulse bag filter, properly prolonging the cleaning time, increasing the amount of compressed air and induced air sprayed into the filter bag, shortening the cleaning cycle and even adopting the continuous cleaning method, the filter bag can be cleaned more thoroughly and the operation resistance can be effectively reduced.
Cleaning period and time are important factors affecting capture performance and operation status.
The cleaning period and time are related to the cleaning methods adopted and the properties of the objects to be treated. Therefore, it is necessary to understand the dust properties and dust concentration, and make necessary checks before determining them. According to the principle of determining the cleaning period and time, according to different cleaning methods, different cleaning settings should be adopted. The first consideration is to retain the next attachment layer on the filter bag to ensure less effective cleaning time and determine the cleaning period. The cleaning cycle is as long as possible and the cleaning time is as short as possible, so that it can operate under the condition of economic resistance of dust removal equipment.
Air back-blowing type: If the cleaning time is too short, the dust on the filter bag will be transferred to work before it is completely cleared, which will make the resistance recover quickly and gradually increase. On the contrary, if the cleaning time is too long, the filtering speed will increase due to excessive cleaning, and the dust can penetrate into the inside of the filter cloth, resulting in the blockage and damage of the filter bag.
Vibration soot cleaning mode: basically the same as air back-blowing soot cleaning mode, while the driving part of the failure is also one of the reasons.
Pulse cleaning type: If the cleaning time is too short, the excessive and frequent cleaning will cause the dust to penetrate into the filter cloth and cause the filter bag to be blocked and damaged. On the contrary, if the cleaning time is too long, the dust accumulation on the filter bag will make the equipment in high resistance operation.

The history of industrial furnaces development The invention and development of industrial furnaces play an important role in human progress. In the Shang Dynasty, China presented a relatively perfect copper smelting furnace, with furnace temperature reaching 1200 C and furnace inner diameter reaching 0.8 M. During the Spring and Autumn Period and the Warring States Period, on the basis of copper smelting furnace, we further grasped the skill of improving furnace temperature, and then produced cast iron.
In 1794, the world presented a cylindrical Cupola for melting cast iron. Later, in 1864, Martin, a Frenchman, used the regenerative furnace principle of Siemens, an Englishman, to create a front-end steel-making open-hearth furnace heated by gas fuel. He used regenerator to preheat air and gas at high temperature, and then ensured that the temperature needed for steelmaking was more than 1600 degrees Celsius. Around 1900, the power supply was gradually adequate, and various resistance furnaces, electric arc furnaces and cored induction furnaces were used.
In the 1950s, coreless induction furnace was developed rapidly. The electron beam furnace, which uses the electron beam to impact the solid fuel, can enhance the appearance of heating and melting high melting point data. The furnace used for casting heating was a hand forge furnace earlier. Its working space was a concave groove. Coal was filled in the groove. The air for incineration was supplied from the lower part of the groove, and the workpiece was buried in the coal for heating. This kind of furnace has low thermal efficiency and poor heating quality, and can only heat small workpieces. Later, chamber furnaces built with refractory bricks can be used for semi-enclosed or fully enclosed furnaces. Coal, gas or oil can be used as fuel or electricity can be used as heat source. Workpieces can be heated in the furnace.
In order to facilitate the heating of large workpieces, a trolley type furnace suitable for heating ingots and billets is presented, and a well type furnace is also presented for heating long rods. Since the 1920s, various mechanized and active types of furnaces have emerged, which can improve the output rate of furnaces and the working conditions.
With the development of fuel capital and the advancement of fuel conversion skills, the fuel of industrial furnaces has gradually changed from solid fuels such as lump coal, coke and pulverized coal to gaseous and liquid fuels such as producer gas, city gas, natural gas, diesel oil and fuel oil, and various incineration equipments suitable for the fuels used have been developed.
The structure of industrial furnace, heating process, temperature control and atmosphere in furnace will directly affect the quality of processed products. In the heating furnace of casting, increasing the heating temperature of metals can reduce the deformation resistance, but too high temperature can cause grain growth, oxidation or over-burning, which seriously affects the quality of the workpiece. In the heat treatment process, if the steel is heated to a point above the critical temperature and then cooled abruptly, the hardness and strength of the steel can be improved; if the steel is heated to a point below the critical temperature and cooled slowly, the hardness of the steel can be reduced and the resistance can be improved.
In order to obtain workpieces with accurate scale and smooth appearance, or to reduce metal oxidation to achieve the intention of maintaining dies and reducing processing allowance, various kinds of less oxidation-free heating furnaces can be selected. In an open flame furnace with little or no oxidation, the recovery gas is produced by incomplete incineration of fuel, in which the oxidation loss rate can be reduced to less than 0.3% by heating the workpiece.
Controllable atmosphere furnace is a kind of artificial atmosphere, which can be used for gas carburizing, carbonitriding, bright quenching, normalizing, annealing and other heat treatment in order to achieve the intention of changing metallographic arrangement and improving the mechanical properties of the workpiece. In the movable particle furnace, burning gases of fuel or other fluidizers applied externally are used to forcibly flow through graphite particles or other lazy particle layers on the furnace bed. Workpieces buried in the particle layers may be heated intensively, and all kinds of non-oxidizing heating such as carburizing and nitriding can also be carried out. In the salt bath furnace, molten salt liquid is used as heating medium to prevent oxidation and decarbonization of the workpiece. Cast iron smelting in cupola is often affected by coke quality, air supply method, burden condition and air temperature, which makes the smelting process difficult to be stable and to obtain high quality hot metal. Hot blast cupola can effectively improve hot metal temperature, reduce alloy burning loss, reduce the oxidation rate of hot metal, and then produce high-grade cast iron.
With the appearance of coreless induction furnace, cupola has gradually been replaced. The smelting operation of this induction furnace is not limited by any grade of cast iron. It can be quickly changed from smelting one grade of cast iron to smelting another grade of cast iron, which is conducive to improving the quality of molten iron. Some special alloy steels, such as ultra-low carbon stainless steel and steels for rolls and steam turbine rotors, need to melt molten steel from open hearth or arc furnace, remove impurities in refining furnace by vacuum degassing and argon agitation, and further refine high purity and large capacity of high-quality molten steel.
Flame furnaces have a wide range of fuels, low quotation, easy to adopt different structures, which is conducive to reducing production costs. However, flame furnaces are difficult to operate accurately and cause serious environmental pollution and low thermal efficiency. The characteristics of the electric furnace are that the furnace temperature is uniform and easy to complete active control, and the heating quality is good. According to the energy conversion method, the electric furnace can be divided into resistance furnace, induction furnace and arc furnace. Furnace heating capacity calculated by unit time per unit area of furnace bottom is called furnace yield. The faster the heating rate of the furnace and the larger the load of the furnace, the higher the productivity of the furnace. Normally, the higher the furnace yield, the lower the unit heat consumption per kilogram of material. Therefore, in order to reduce energy consumption, full-load production should be carried out, furnace production rate should be improved as far as possible, and active share of fuel and combustion-supporting air should be adjusted for incineration equipment to prevent emptiness.