Energy Saving Needs And Waste Heat Value in The Steel Industry
Technical principle: Energy saving mechanism of multidimensional capture and cascade conversion
The waste heat recovery of steel plant boilers is based on the principle of thermodynamic heat transfer, and adopts differentiated technical paths to achieve efficient energy conversion for waste heat resources of different temperature levels
Graded recycling system: According to the temperature of waste heat, it is divided into three levels of recycling: high temperature (above 600 ℃), medium temperature (200-600 ℃), and low temperature (below 200 ℃). High temperature waste heat (such as sintering flue gas and blast furnace slag) is used to generate high-pressure steam through a waste heat boiler to drive power generation; Medium temperature waste heat (such as coke oven gas and steel rolling waste gas) is used for heating or supplying heat in production processes; Low temperature waste heat (such as flue gas and condensed water after desulfurization) is recovered through a fluoroplastic steel heat exchanger to achieve deep energy saving.
Core heat transfer technology: Advanced technologies such as H-shaped finned tube heat transfer, porous medium combustion, and vortex tube plate heat transfer are adopted to enhance heat transfer efficiency. For example, the H-shaped finned tube adopts a multi stroke heat transfer design, which enables deoxygenated water to absorb heat from flue gas and convert it into high-temperature hot water, which is then generated into saturated steam through the evaporator. The heat transfer efficiency is improved by 15% -20% compared to traditional equipment; Porous media combustion technology utilizes the material's heat storage capacity to recover high-temperature flue gas waste heat, preheat combustion gases to reduce energy consumption.
Diversified conversion path: forming a multi-dimensional utilization model of "power generation+heating+process reuse". High temperature waste heat is converted into electrical energy through a steam turbine generator unit, while medium and low temperature waste heat is used for urban heating or reused in production processes (such as blast furnace dehumidification and sintering preheating) through a heat exchange system, achieving maximum energy cascade utilization.
Core technology and equipment: specialized design adapted to steel working conditions
The efficient operation of the waste heat recovery system for steel plant boilers relies on targeted technological equipment innovation:
High temperature waste heat power generation equipment: a super large high-efficiency energy-saving blast furnace gas residual pressure recovery turbine power generation device (TRT), which captures the pressure energy of the blast furnace top gas and drives the turbine expander to do work and generate electricity, with a system efficiency of up to 92%; The clean coke oven waste heat power generation system adopts high temperature and ultra-high pressure intermediate reheating technology to convert coke oven flue gas waste heat into high parameter steam, promote steam turbine power generation, and lead the industry in comprehensive energy efficiency.
Low temperature waste heat recovery equipment: Fluoroplastic steel new material low-temperature economizer and condenser, respectively arranged before and after the desulfurization tower, to recover the sensible and latent heat of flue gas, and can reduce the exhaust gas temperature to below 150 ℃; Intelligent integrated heat exchangers, vortex tube plate heat exchangers, and other equipment have solved the working conditions of steel waste heat containing dust, sulfur, and intermittent fluctuations, and improved the utilization rate of low-temperature waste heat.
Intelligent control system: Through the energy management center, full process monitoring and scheduling are achieved, real-time collection of parameters such as boiler flue gas temperature, pressure, flow rate, etc., and intelligent matching of recovery equipment operating load. For example, the energy control platform built by Puyang Iron and Steel controls the gas release rate within 0.5% and saves 94000 tons of standard coal annually.
Industry Trend: Technological Upgrade Leads Deep Energy Conservation
Driven by the dual goals of "dual carbon" and high-quality industry development, the waste heat recovery technology of steel plant boilers is upgrading in three major directions:
Full process integration: Breaking down process barriers, integrating waste heat resources from sintering, coking, ironmaking, steel rolling and other processes, and building a cross process cascade utilization system. For example, in the waste heat recovery project of Baosteel's circular furnace in Shanghai, the sensible and latent heat of exhaust gas are recovered through a dual-purpose condensing boiler, achieving full chain energy recovery.
Deep utilization of low-temperature waste heat: Focusing on low-temperature waste heat resources below 200 ℃, promoting technologies such as fluoroplastic steel condensation recovery and phase change heat storage, further reducing exhaust gas temperature, and improving waste heat utilization efficiency. For example, the Zhejiang Materials and Environmental Energy Project has saved 8388 tons of standard coal annually by recovering waste heat before and after desulfurization towers.
Intelligence and Greenization: Integrating IoT and big data technologies to achieve dynamic control and fault warning of waste heat recovery systems; At the same time, promote green materials such as fluorine free heat exchange media and high-efficiency environmentally friendly coatings, reduce the carbon footprint of equipment, and promote the steel industry to move towards "near zero emissions".
As a core technology for energy conservation and carbon reduction in the steel industry, boiler waste heat recovery is shifting from single process recovery to full process collaboration, from high-temperature waste heat utilization to deep mining at low temperatures, and from traditional equipment to intelligent green upgrading, providing sustained power for the steel industry to achieve energy efficiency benchmark creation and low-carbon transformation.
