The disclosure provides a collective exhaust system capable of safely detecting a closing failure of a check valve of the collective exhaust system. The collective exhaust system includes: multiple combustion devices including blowing parts and exhaust pipes; a collective exhaust duct to which the exhaust pipes of the multiple combustion devices are respectively connected; and check valves respectively provided between the exhaust pipes and the collective exhaust duct. The collective exhaust system is configured to detect a closing failure of the check valves by performing, in a state where one of the blowing parts of the multiple combustion devices is stopped and all the other blowing parts are driven with a predetermined blower capacity, a backflow determination from the collective exhaust duct to the combustion device with the stopped blowing part, and by performing the backflow determination for the multiple combustion devices.

Presented is a process for the regeneration of a deactivated nitrogen oxide decomposition catalyst of a selective catalytic reduction system that is a component of a flue gas treating system that is one of parallel flue gas treating systems. The selective catalytic reduction system is isolated to provide a closed system in which a regeneration gas is circulated to regenerate the deactivated nitrogen oxide decomposition catalyst. Denitrified flue gas from a parallel flue gas treating system is introduced and used within the closed system as regeneration gas.

Flue gas entry into the tunnel(s) of a furnace is controlled by openings through the entry ports. A furnace tunnel assembly system uses interlocking refractory blocks to form a longitudinal wall of a flue gas flow channel in a firebox. Plugs in some of the ports inhibit flue gas entry from the firebox to the flow channel, and flow passages in some of the ports allow the flue gas to enter the flow channel from the firebox. The flow passages can be provided as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

Flue gas entry into the tunnel(s) of a furnace is controlled by openings through the entry ports. A furnace tunnel assembly system uses interlocking refractory blocks to form a longitudinal wall of a flue gas flow channel in a firebox. Plugs in some of the ports inhibit flue gas entry from the firebox to the flow channel, and flow passages in some of the ports allow the flue gas to enter the flow channel from the firebox. The flow passages can be provided as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

Presented is a process for the regeneration of a deactivated nitrogen oxide decomposition catalyst of a selective catalytic reduction system that is a component of a flue gas treating system that is one of parallel flue gas treating systems. The selective catalytic reduction system is isolated to provide a closed system in which a regeneration gas is circulated to regenerate the deactivated nitrogen oxide decomposition catalyst. Denitrified flue gas from a parallel flue gas treating system is introduced and used within the closed system as regeneration gas.

A combustion device includes a combustion control section which controls combustion in the combustion device; a setting section operated to set information indicating whether or not a plurality of combustion devices are in a common vent discharge state; and a memory section which stores therein connection configurations with the other combustion control sections to which the combustion control section is communicatively connected, and the combustion control section determines whether or not the combustion control section can communicate with a linkage control section or the other combustion control sections, and inhibits combustion in the combustion device to which the combustion control section belongs, in a case where the combustion control section determines that the combustion control section cannot communicate with the linkage control section or at least one of the other combustion control sections and the common vent discharge state is set by the setting section.

A combustion device includes a combustion control section which controls combustion in the combustion device; a setting section operated to set information indicating whether or not a plurality of combustion devices are in a common vent discharge state; and a memory section which stores therein connection configurations with the other combustion control sections to which the combustion control section is communicatively connected, and the combustion control section determines whether or not the combustion control section can communicate with a linkage control section or the other combustion control sections, and inhibits combustion in the combustion device to which the combustion control section belongs, in a case where the combustion control section determines that the combustion control section cannot communicate with the linkage control section or at least one of the other combustion control sections and the common vent discharge state is set by the setting section.

Flue gas entry into the tunnel(s) of a furnace is controlled by varying the flow conductivity or size of the individual or groups of openings through the entry ports. The openings can be provided either as gaps between adjacent blocks, or through bores of varying diameter, or as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

Flue gas entry into the tunnel(s) of a furnace is controlled by varying the flow conductivity or size of the individual or groups of openings through the entry ports. The openings can be provided either as gaps between adjacent blocks, or through bores of varying diameter, or as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

Reversible draft controllers and exhaust systems incorporating reversible draft controllers are disclosed. One system for controlling draft in a chimney includes a sensor for determining condition data, an axial fan blade, an electronically commutated motor (ECM), and a controller. The ECM is configured to rotate the fan blade in a first direction to increase draft in the chimney and in a second, opposite direction to decrease draft. The controller has a processor and a program of instructions executable by the processor to perform steps for controlling draft in the chimney with the fan blade. The steps include: comparing condition data from the sensor to set point data to determine if an intervention is required; addressing insufficient draft by actuating the ECM to rotate the axial fan blade in the first direction; and addressing excessive draft by actuating the ECM to rotate the fan blade in the second direction.