Built-in Direct-Fired Hot Air Furnace Series

Application: Used for supplementary combustion heating in flue gas desulfurization and denitrification, waste heat boilers, etc.

Working Principle:

The flue gas heating system utilizes a built-in burner to directly heat the flue gas within the duct. The high-temperature flue gas generated by combustion directly exchanges heat with the flue gas to be heated through convection, with no associated heat loss. It employs high-energy ignition or plasma ignition (no need for a high-calorific-value gas ignition system), using high-temperature flue gas as combustion air (flue gas temperature 100-150°C, oxygen content about 16%). The flue gas directly passes through the high-temperature outer flame zone of the flame for mixing.

Main Performance and Features:

★ A heat storage device is installed at the outlet of the low-calorific-value gas burner to ensure stable combustion and prevent flameout;

★ The built-in direct-fired burner operates directly within the flue duct, eliminating system heat dissipation, requiring no air blending, achieving high combustion efficiency, and saving fuel;

★ Direct heating ensures rapid and uniform mixing of flue gas, with no need for castable refractories in the duct;

★ Capable of burning part of the CO contained in the original flue gas, saving gas and reducing the oxygen content of the flue gas;

★ A side-mounted heating method can be adopted to mix high-temperature flue gas with the flue gas to be heated via swirling, rapidly reducing the outlet temperature of the hot air and effectively decreasing system mixing resistance;

★ Fuel quantity can be automatically or manually adjusted based on flue gas volume and temperature;

★ Occupies minimal space, requires no furnace drying before use, offers convenient operation and maintenance, and reduces overall investment;

Composition:

Burner, valve system, fan, heat storage and flame stabilization device, high-temperature flue gas distribution device, PLC control, etc.;

Combustion Air System:

Uses high-temperature flue gas (high oxygen) after GGH heat exchange for combustion assistance, minimizing flue gas increment and absorbing tail exhaust heat; equipped with an emergency combustion air valve that can draw external air for combustion assistance when flue gas composition is unstable.

Control System:

This PLC thermal automation control system is a general-purpose thermal measurement and control system specifically designed for desulfurization and denitrification direct-fired furnaces. The normal operation status of the direct-fired furnace is marked by a reasonable ratio of gas volume to air blast volume, ensuring that the furnace temperature and outlet flue gas temperature are controlled within a certain range to achieve the purpose of heating the catalyst. For different process scenarios, the selection of measurement and control parameters may vary.

This control system has manual and automatic control functions. The automatic functions include:

⑴. Automatic purging (pre-purge, post-purge), programmed ignition, and automatic flameout protection;

⑵. Gas valve leakage alarm and protection;

⑶. High and low gas pressure alarm and protection;

⑷. Overtemperature alarm and protection;

⑸. External fault alarm and protection;

⑹. Automatic adjustment of gas volume and combustion air volume;

⑺. Centralized display of process parameters such as temperature, pressure, valve position, and flow rate on the touch screen, as well as control functions for starting/stopping and switching process equipment, monitoring the operating status of each process equipment;

⑻. Manual/automatic switching function.

According to the needs of the central control DCS system, this PLC system can communicate with the central control DCS system;

Communication methods include Ethernet, Profibus DP, Profinet, Modbus RTU, Modbus TCP, and point-to-point, meaning this thermal PLC control system for the gas furnace can exchange data with the central control DCS system through the above communication methods, thereby enabling the central control DCS system to remotely operate the onsite hot air furnace equipment.

Site Photos:

Flue Gas Mixing Flow Field Simulation Analysis and Customer Evaluation: