Use of process gases in combined heat and power plants
The chart illustrates the use of process gases to make electricity and heat in the combined heat and power plants.
Energy efficiency in practice
Energy efficiency applies to the whole production chain and the need for purchased fuels is reduced by optimizing which process gases can be utilized for which processes. Additionally, the production of electricity and heat is maximized in terms of heat value and volume by optimizing the supply of process gases to the power plant. The most fundamental part of improving energy efficiency is to constantly question if energy usage is optimized, as well as analyzing the actual need in different processes (shutdowns, different production levels, etc.). Below are some examples of activities to improve efficiency, based on experiences from SSAB’s operations and split into optimization, productivity, use and maintenance.
Reduced output pressure in media system (compressed air, etc.)
Cooling water, adjust output pressure according to need due to inlet temperature
Optimize pump groups (3 running instead of 4, etc.) to run on optimum operation point (cooling water, hydraulic system, etc.)
Furnaces, short stops (10 min to 8 h) manual ramp-down and control
Furnaces, long stops (>8 h), manual set-point for lower temperature
Furnaces, analyze oxygen level in flue gasses, optimize burners
Routines to stop equipment not needed when production is shut down
Hot charging of reheating furnaces
Routines to shut down equipment during maintenance, disruption, etc。
Switch to optimized lighting source
Customize lighting after need, presence-controlled, etc.
Leakage control in media system (compressed air, water, air, gases, etc。)
Analyze efficiency on pumps, fans, compressors, etc. Change equipment if efficiency is poor due to high wear or wrong sizing
Analyze efficiency on control valves, change if performance is poor due to high wear or wrong sizing