1. Industry introduction:
Steel smelting uses industrial gas as fuel. Because it involves blast furnace gas, converter gas, and coke oven gas with high carbon content, it may be due to lack of gas
Explosion accident caused by leakage detection of flammable gas. Safety protection inspection in steel enterprises to use LEL to monitor the total concentration of combustible gas
For the lord. Monitoring the concentration of combustible gases can track the changes in gas concentrations in the environment. If the gas reaches a certain concentration, the instrument can be released
Send out an alarm signal to warn the surrounding people that there is a gas leak nearby, and they should evacuate immediately and take emergency measures to avoid further development and occurrence of the situation
explosions and other accidents.
2. Process introduction:
The main difference between steel and pig iron in terms of chemical composition is the carbon content, with a carbon content of more than 2.11% being pig iron, while the carbon content of commonly used steel is average
Below 1%. Steelmaking is actually a refining process to reduce the carbon content in pig iron. At present, oxygen top-blowing converter steelmaking is the smelting of ordinary steel
The main means, electric arc furnace steelmaking has developed rapidly, mainly used for smelting high-quality alloy steel.
Converter steelmaking process: blast furnace molten iron→ molten iron pretreatment→ reblowing converter steelmaking→ outer refining→ continuous casting→ hot rolling
3. Environmental characteristics and requirements for gas detectors:
※ High working intensity and high ambient temperature. Some detection ambient temperatures up to +120°C.
※ Equipment is dense and difficult to maintain.
※ The equipment and system are fast and have a high level of safety.
※ The equipment works stably, has a long service life and low maintenance.
※ The on-site gas detectors are all made of 316 stainless steel, which is resistant to high temperature and corrosion.
4. Gases to be detected:
During the steelmaking process, the following gases need to be detected:
※ Flammable gases: hydrocarbon flammable and explosive gases such as methane and propane
※ carbon monoxide
※ hydrogen
※ oxygen
5. Layout of detector:
The steelmaking process involves a large amount of blast furnace gas, converter gas, and coke oven gas with high carbon content, so the flammable gas detection system is required
Cover all areas where gas leakage may occur, and the specific point selection and layout should consider the following points:
In converters, electric arc furnaces, and refining furnaces that are prone to leakage, detector will be detected in the possible ways of potential flammable gas release, and
By moving the detector closer to the potential flammable gas release source, the sensitivity of the detector is improved to a certain extent.
When determining the specific location of detectors at the infeed, outfeed, and degassing pipe openings, it should be noted that some detectors are sensitive to location and airflow.
According to whether the density of the leaking gas is greater than that of air, combined with the air flow trend, the detector arrangement is comprehensively completed.
6. Introduction to gas detection system:
A typical gas detection system in the steelmaking process looks like this:
As shown in the figure above, gas detectors that detect flammable gas, carbon monoxide, hydrogen, and oxygen can be installed according to the actual situation in each steelmaking process. In some converters or combustion processes, a detector that can detect flammable gases at high temperatures is required.
Honeywell's patented Sensepoint-HT high-temperature combustible gas detector is a very advanced combustible gas detector produced specifically for this special application.
The Sensepoint-HT type is made of 316 stainless steel as a whole, and has a special high-temperature resistance inside, which can accurately and stably detect the leakage of combustible gases in the ultra-wide temperature range of -40°C ~ +150°C. This is the most advanced in the entire industry.
The signal from the on-site gas detector is transmitted to the System57 gas alarm controller. The System57 gas alarm controller adopts an independent board structure, and each channel works completely independently. Depending on the user's needs, the System57 gas alarm controller can be used for every detector on site
It outputs three relay signals: high alarm (A1), high alarm (A2) and fault. The System57 is also capable of outputting 4-20mA analog signals and RS-485Modbus signals according to user requirements.
In practical applications, the System57's relay signals are often transmitted to the production control PLC as a linkage signal for alarms and emergency stops.
The 4-20mA analog signal and RS-485Modbus signal are often transmitted to the upper monitoring system for real-time control and data acquisition of the production control system.
