A heat exchange flue, having a top flue gas chamber (1), a bottom flue gas chamber (10) and a heat exchange section (H) located therebetween. The heat exchange section (H) comprises a heat exchange tube bundle (4) located in the middle, and a left side flue (5) and a right side flue (12) which are located at two sides of the heat exchange tube bundle (4). The axis of the heat exchange tube bundle (4) is positioned in a vertical plane extending substantially forward and backward, allowing the flue gas to laterally flush against the surfaces of heat exchange tubes. The left and right side flues (5, 12) are in a vertical box shape, the flues are each provided with a plurality of flue gas dampers (3) which are vertically arranged at intervals in a substantially horizontal alignment. Each of the flue gas dampers (3) is provided with a flue gas damper frame (13) for defining a flue gas port (2) and a flue gas port opening/closing device capable of selectively opening and closing the flue gas port (2). The flue gas damper frames (13) are hollow out and horizontally arranged, and have an outer contour consistent with the sectional shape of the left and right side flues (5, 12), the peripheral edges thereof are respectively connected to a peripheral flue gas wall in an airtight manner, and the parts thereof corresponding to the heat exchange tube bundle (4) are connected to a substantially horizontal flue gas shield plate (6) in an airtight manner. The flue structure can adjust the working load to the greatest extent to ensure the flue gas temperature and prevent condensation.

A circulating fluidized bed boiler includes a rectangular furnace, which is horizontally enclosed by sidewalls, for combusting fuel and combustion gas and generating a stream of flue gas and particles. The sidewalls include first and second short sidewalls and first and second long sidewalls. Multiple particle separators are arranged on the side of each of the first and second long sidewalls for separating particles from the stream of flue gas and particles discharged from the furnace. Each of the particle separators includes a vertical gas outlet tube for discharging cleaned flue gas from the particle separator. A back pass arranged on the side of the second short sidewall of the furnace is horizontally enclosed by back pass walls. A horizontally extending cross over duct system is directly connected to the vertical gas outlet tubes of the particle separators for conducting the cleaned flue gas to the back pass.

An air pollution control system includes a denitration device that removes nitrogen oxide in flue gas from a boiler; a heat transfer tube for recovering part of heat of the flue gas after denitration; a precipitator that removes soot and dust in the flue gas after heat recovery; a desulfurization device that removes sulfur oxide in the flue gas discharged from the precipitator; a heat transfer tube for heating the flue gas discharged from the desulfurization device; a circulation pump that circulates a heat medium between the heat transfer tubes; a heat medium heater provided to the circulation pipe to heat the heat medium; and a control device that controls the heat medium heater based on an ammonia concentration at an outlet of the denitration device. The control device causes the heat medium heater to heat the heat medium when the ammonia concentration is higher than a certain value.

An air pollution control system includes adenitration device that removes nitrogen oxide in flue gas from a boiler; a heat transfer tube for recovering part of heat of the flue gas after denitration; a precipitator that removes soot and dust in the flue gas after heat recovery; a desulfurization device that removes sulfur oxide in the flue gas discharged from the precipitator; a heat transfer tube for heating the flue gas discharged from the desulfurization device; a circulation pump that circulates a heat medium between the heat transfer tubes; a heat medium heater provided to the circulation pipe to heat the heat medium; and a control device that controls the heat medium heater based on an ammonia concentration at an outlet of the denitration device. The control device causes the heat medium heater to heat the heat medium when the ammonia concentration is higher than a certain value.

A circulating fluidized bed boiler includes a rectangular furnace, which is horizontally enclosed by sidewalls, for combusting fuel and combustion gas and generating a stream of flue gas and particles. The sidewalls include first and second short sidewalls and first and second long sidewalls. Multiple particle separators are arranged on the side of each of the first and second long sidewalls for separating particles from the stream of flue gas and particles discharged from the furnace. Each of the particle separators includes a vertical gas outlet tube for discharging cleaned flue gas from the particle separator. A back pass arranged on the side of the second short sidewall of the furnace is horizontally enclosed by back pass walls. A horizontally extending cross over duct system is directly connected to the vertical gas outlet tubes of the particle separators for conducting the cleaned flue gas to the back pass.

A combustion system includes a perforated flame holder positioned within a combustion volume, a nozzle configured to emit a fuel stream toward the perforated flame holder, an oxidant source configured to introduce an oxidizer fluid into the combustion volume, and a flue gas recirculation (FGR) channel having a first end in fluid communication with the combustion volume downstream of the perforated flame holder and a second end in fluid communication with the oxidant source. A controller is configured to hold a combustion parameter within a selected range of values by regulating a quantity of flue gas flowing in the FGR channel.

A heat exchange flue has a top flue gas chamber, a bottom flue gas chamber, and a heat exchange section located therebetween that includes a heat exchange tube bundle located in the middle and a left side flue and a right side flue located at two sides of the heat exchange tube bundle. The axis of the heat exchange tube bundle is positioned in a vertical plane extending substantially forward and backward, allowing the flue gas to laterally flush against the surfaces of heat exchange tubes. The left and right side flues are in a vertical box shape, and the flues are each provided with a plurality of flue gas dampers (3). Each of the flue gas dampers is provided with a flue gas damper frame for defining a flue gas port and a flue gas port opening/closing device capable of selectively opening and closing the flue gas port.