Technical measures and safe application of CG meth

Technical measures and safe application of pure dry dedusting process (CG method)

as a new dedusting process, the pure dry dedusting process of converter flue gas (CG method) not only ensures the energy saving, emission reduction, comprehensive utilization of resources and economic benefits of the dedusting process, but also greatly improves its safety. This paper briefly introduces the characteristics, safety theory and related technical measures of CG method

the new process of converter flue gas waste heat recovery and comprehensive utilization of pure dry dedusting is composed of 3 + 1 subsystems, namely, the main process 3 subsystems: high temperature flue gas cooling synchronous waste heat recovery subsystem, pure dry dedusting and ash conveying subsystem, pure dry gas cooling recovery and waste gas emission subsystem; A furnace dust resource subsystem is set outside the main process

the new dust removal process is different from the current dust removal process:

1) converter ℃ flue gas waste heat is converted into steam recovery

2) the converter flue gas is cooled without water spray, and the flue gas is pure dry flue gas

3) the gas is cooled without water spray, and the gas is pure dry gas

4) flue gas dedusting is pure dry method, coarse dedusting + fine dedusting

5) the furnace dust is made into functional charge by batching and returned to the converter for smelting - resource and efficient utilization

process characteristics of CG method

1) the CG method process adapts to and uses the laws and characteristics of converter flue gas. The flue gas moves rapidly through the suction of induced draft fan. During the operation, the flue gas passes through the process equipment of various functions to realize the automatic cooling of flue gas, automatic heat exchange and steam production, automatic separation of flue gas, and automatic cooling of gas, so as to form a dry and brand-new dust removal process

2) maximize the efficiency of the three resources (℃ heat energy, 70% Co, FeO, Cao and MgO furnace dust) of converter flue gas dedusted by this process

3) water and electricity saving during dust removal

4) the dust removal process is not only the process of reaching the emission standard, but also the process of creating economic benefits, which is simplified into a mathematical formula, namely: CG method = converter flue gas waste heat recovery and comprehensive utilization + pure dry dust removal = emission standard + economic benefits

main indicators of the operation of the new NCG dust removal process

1) high temperature flue gas cooling

inlet flue gas temperature: ℃; Outlet temperature: ℃

2) gas cooling temperature

inlet gas temperature: ℃; Outlet temperature: ℃

3) dust concentration of flue gas

dust concentration before dust removal and purification: g/m3; Dust concentration after purification: <10mg/m3 (purification standard can be improved according to user needs)

4) steam recovery per ton of steel

kg (the steam pressure is the same as that of the vaporization flue)

5) fan operation

temperature: about 150 ℃; Wind pressure: about 15kpa; Air volume: 1/3 lower than the flue gas volume of water spraying process

three NCG new process safety theory and related technical measures

1. Converter flue gas waste heat recovery system safety theory and related technical measures

converter high temperature flue gas cooling synchronous waste heat recovery subsystem main process equipment is vertical flue type waste heat boiler, its heat exchange principle is: convection conduction convection mode, converter flue gas passes through the waste heat boiler flue, the flue gas is automatically cooled, and the heat energy is automatically converted into steam. In order to ensure the safety of the vertical flue type waste heat boiler and follow the safety theory, the "five fold" protection measures are taken:

1) high temperature combustion protection - the waste heat boiler used in the process research and development follows the combustion temperature theory in CO air

is an explosion-proof vertical flue type waste heat boiler, which adopts a special vertical flue type furnace body structure. One of the structural features of this structure is that the high temperature section is on the top, and the high-temperature flue gas of the converter enters from the top of the furnace body, After being cooled by the furnace body, it is led out from the bottom. In the cooling process, the flue gas inlet temperature and outlet temperature are about 200 ℃, and in the middle and upper part of the furnace body, it must pass through the 600 ℃ ignition zone of CO combustible flue gas; The second feature is that the boiler heat exchange tubes are arranged horizontally, forming a vertical impact with the flue gas flow, so that the flue gas instantly becomes turbulent. Once the co combustible flue gas meets air, it will be instantly mixed; Above the ignition point of 600 ℃, as long as the co combustible flue gas accidentally encounters air (O2) and is quickly mixed, it will burn immediately without explosion. After combustion, a new inert flue gas section is generated and enters the low-temperature area of the waste heat boiler. This inert flue gas section plays an isolation role. As long as the low-temperature area of the waste heat boiler is well sealed, there is no possibility of explosion of the waste heat boiler

this special structure of vertical flue type waste heat boiler is developed based on the principle of CO ignition temperature. It becomes a safety barrier for converter high-temperature flue gas cooling and synchronous waste heat recovery, and the flue gas does not explode

2) protection of inert flue gas section - follow the combustible flue gas and air isolation theory

the inert flue gas section is from the beginning and end of oxygen blowing, vaporization flue inlet combustion; The second is from the combustion in the high temperature zone of the vertical flue waste heat boiler

inert flue gas section, this inert flue gas is neither combustion supporting flue gas nor combustible flue gas, and it does not burn and explode in contact with combustible flue gas; It does not burn or explode in contact with combustion supporting flue gas. The inert flue gas section effectively protects the waste heat boiler plastic film, wires and cables, waterproof coiled materials, metal wires, cartons and other materials, especially the low-temperature area of the waste heat boiler and the subsequent dust removal system

3) the waste heat boiler is protected by the sealing structure of the furnace body to recover to the required flow in real time - following the theory of isolation between combustible flue gas and external air

the combustible converter flue gas below the combustion point temperature can no longer contact the air. In order to adapt to this characteristic of converter flue gas, the waste heat boiler is developed into a sealing structure, and all furnace walls are welded by boiler steel plates, and after pressure detection, there can be no leakage; The bin valves of the ash cleaning system of the waste heat boiler are designed as air locking mechanisms to ensure that no air enters during the ash cleaning process. The sealing structure of the waste heat boiler ensures that there is no air outside, and the combustible flue gas of the converter will not explode

4) protection of anti explosion structure and pressure relief mechanism of waste heat boiler - follow the principle of safety accident

in line with the principle that anti explosion and pressure relief must be set when there is co flue gas, high-temperature flue gas cooling is synchronized with waste heat recovery process equipment, and an anti explosion waste heat boiler is developed. The furnace body is a cylindrical or square boiler with reinforced structure; In addition, pressure relief valves with automatic reset function are installed at many parts of the furnace body to protect the boiler body from damage, personal injury, equipment and converter smelting in case of accidental explosion

5) install a "flue gas preprocessor" in front of the inlet of the waste heat boiler - follow the principle of prevention first

the flue gas preprocessor is equivalent to a "firewall" to prevent some adverse factors in the converter smelting process from affecting the safe operation of the waste heat boiler and the micro nano scale 3D printing technology furnace developed by its team

the above "five protection" can ensure the safe operation of flue gas cooling and waste heat recovery process equipment. Even if the converter operation is abnormal, "five protection" can still play a role

2. Safety theory and relevant technical measures of pure dry dust removal subsystem

the pure dry dust removal subsystem is composed of coarse dust collector + fine dust collector. According to the different configuration of fine dust collector, two kinds of pure dry dust removal processes are formed: bag pure dry dust removal process -cg (b); Pure dry electrostatic precipitation process -cg (d)

the bag pure dry dust removal subsystem is composed of coarse dust collector - circulating cyclone dust collector + fine dust collector - bag + pneumatic ash conveying system

after the converter flue gas passes through the vertical flue type waste heat boiler, the flue gas temperature drops to about 200 ℃, the coarse dust collector removes more than 80% of the dust, and the flue gas passes through the bag dedusting to meet the standard. Once the bag explodes, it will lose its dust removal function. Therefore, safety and non explosion become the key to the application of cloth bags in converter flue gas dust removal

in order to ensure the safety of bag dust removal system, the following safety theory should be followed:

1) flue gas diversion - follow the theory of combustible flue gas and air isolation

the flue gas is divided into combustible flue gas and combustion supporting flue gas, and each has its own way. If combustible flue gas and combustion supporting flue gas do not contact and mix, the possibility of explosion will be lost

analysis on the principle of tensile test of laces breaking force

2) double bag dust removal system -- follow the limit theory of CO combustible flue gas and air mixing ratio

different types of flue gas enter their respective dust removal systems, and each system becomes a safe dust removal system

3) the combustible flue gas dust removal system is made into a sealed structure - following the theory of combustible flue gas and air isolation

4) the combustible flue gas dust removal system is made into an explosion-proof and pressure relief structure - following the theory of combustible flue gas and air isolation

5) detect co% and O2%, and automatically control the operation - follow the theory of CO combustible flue gas and air mixing ratio limit

the above five aspects constitute the safety system of bag dust removal system, which becomes an explosion-proof and explosion-proof bag dust removal system

3. Adaptability of converter flue gas cooling synchronous waste heat recovery subsystem and pure dry dust removal subsystem to the safety of converter smelting under special working conditions

converter smelting is an extremely special process, which has the characteristics of intense reaction, short cycle and variable working conditions. Some accidents in the smelting process are inevitable. If the silicon in molten iron is too high, splashing will occur; The silicon in molten iron is too low, and the amount of flue gas increases during charging; Scrap steel contains a lot of oil, and the amount of flue gas increases greatly; The oxygen pressure drops instantly, and the gun position is not controlled in place, resulting in splashing; Water leakage of vaporization flue; Sudden power failure; Excessive large particles in flue gas, etc

these special conditions have little impact on the operation of flue gas cooling synchronous waste heat recovery subsystem and pure dry dust removal subsystem. The explosion-proof and explosion-proof vertical flue type waste heat boiler used in the non spray cooling high-temperature flue gas synchronous waste heat recovery subsystem and the circulating cyclone coarse dust collector + bag fine dust collector used in the pure dry dust removal subsystem can meet the safety requirements of converter smelting conditions