At present time, many iron and steel plants use hot-blast stoves with an internal combustion chamber, the main feature of which is parallel placing of the checkerwork and combustion chamber in the same casing. Besides, these hot-blast stoves use a “pipe-in-pipe” burner type, into which BF gas (or a BFG + NG/ COG mix) and fan combustion air is fed.
This solutions has the followig disadvantages.:
– destruction of the lining between the combustion chamber and the checkerwork chamber that leads to mixing of cold and hot blast and, as a consequence, to a decrease of the blast temperature, as well as to an increase of the CO content in flue gas;
– the use of a “pipe-in-pipe” type burner leads to incomplete combustion of CO, uneven distribution of combustion products over the checkerwork, high-temperature creep of refractory bricks in the area of blast-furnace gas combustion under the load of the combustion chamber lining, etc.
– checkerwork blocks with channels with a diameter of 40 mm have a significantly smaller heating surface than those used in modern stoves with channel diameters of 30 and 20 mm.
The described disadvantages in the design of the BF stoves are shown below.
Nonuniform distribution of velocities in the HBS profile along the axis of the “pipe-in-pipe” type burner nozzle.
In its projects M TECHNOLOGY carries out modernization of hot-blast stoves with a minimal change in the existing position (keeping the existing casing, maintenance platforms, valves, etc.).
A ceramic burner is used as a burner arrangement. This solution has the following advantages:
– a ceramic burner improves mixing of air and gas so that combustion is more complete and calorific capacity is higher;
– the flame of the ceramic burner has a strictly vertical trajectory and spreads parallel to the walls of the combustion chamber, what excludes the possibility of local overheating caused by the nonuniform temperature of the partition, and prevents it from burning through (short circuit), which significantly increases the HBS resistance and thermal efficiency;
– the burner operates silently with low gas pressure losses. The flame is well controlled, there is no gas pulsation, and a better heating is provided if compared to “pipe-in-pipe” burners.
General view of a ceramic burner:
Distribution of velocities along the profile of the HBS chamber with a ceramic burner:
To increase the heating surface of the checkerwork chamber our company replaces the existing checkerwork blocks with a cylindrical channel diameter of 40 mm with blocks that have conical channel diameters of 30 and 20 mm. These solutions make it possible to increase the heating surface area of the checkerwork by almost two times.
Example of a checkerwork block with a conical channel diameter of 30 mm:
An Example of efficiency calculation of different types of checkerwork blocks:
All above-mentioned measures make it possible to maximize the efficiency and lifetime of the existing hot-blast stoves with minimum expenses, as well as to improve the environmental and economic performance of the units.
In addition, our company provides a full range of design services for the reconstruction and new construction of both the entire HBS block and individual stoves, which includes, for example: installation of process equipment, design of process pipelines, utility lines, power supply systems, control systems and instrumentation, civil part. Nowadays we have a number of implemented and put in operation projects.
Example of civil structures (process pipeline rack).
Example of process equipment installation.