A vent proving system is described for use with a gas fired appliance. The gas fired appliance includes a gas burner, a vent damper for selectively opening or closing an exhaust vent from the gas fired appliance and a relay control for operatively controlling the vent damper and the gas burner to open the damper if the gas burner is on. The vent proving system comprises a sensor for sensing a variable in the vent representing air flow direction in the vent. An electrical switch is connected in series between the relay control and the vent damper. A controller is operatively connected to the sensor, the electrical switch and to the relay control. The controller determines if a back draft condition is present in the vent when the gas burner is on and selectively operates the electrical switch to open the connection between the relay control and the vent damper if a back draft condition is present in the vent when the gas burner is on.

A thermal power plant has an exhaust gas system, a feed-water system, a high-pressure feed-water heater provided to the feed-water system, a main economizer, a catalytic NOx removal equipment, and a sub economizer. The main economizer is provided to the secondary side of the high-pressure feed-water heater of the feed-water system and increases the temperature of the feed-water by using the residual heat of the combustion gas from the boiler. The catalytic NOx removal equipment is provided to the secondary side of the main economizer of the exhaust gas system. The exhaust gas is supplied to the catalytic NOx removal equipment at a required temperature or higher. The sub economizer is provided between the high-pressure feed-water heater and the main economizer and increases the temperature of water by using the exhaust gas on the secondary side of the NOx removal equipment.

A thermal power plant has an exhaust gas system, a feed-water system, a high-pressure feed-water heater provided to the feed-water system, a main economizer, a catalytic NOx removal equipment, and a sub economizer. The main economizer is provided to the secondary side of the high-pressure feed-water heater of the feed-water system and increases the temperature of the feed-water by using the residual heat of the combustion gas from the boiler. The catalytic NOx removal equipment is provided to the secondary side of the main economizer of the exhaust gas system. The exhaust gas is supplied to the catalytic NOx removal equipment at a required temperature or higher. The sub economizer is provided between the high-pressure feed-water heater and the main economizer and increases the temperature of water by using the exhaust gas on the secondary side of the NOx removal equipment.

Provided is an air pollution control system including: a denitration apparatus; an air heater; a precipitator; a desulfurization apparatus; a dehydrator; a spray drying apparatus provided with a spray unit that is configured to spray dehydrated filtrate as desulfurization wastewater supplied from the dehydrator; a flue gas introduction line through which a branch gas branched from the flue gas is introduced to the spray drying apparatus; a flue gas supply line through which flue gas returns to a main flue gas duct, the flue gas being obtained after the dehydrated filtrate is dried by the spray drying apparatus; and a powder supply apparatus that is configured to supply a powder to the flue gas introduction line.

Provided is an air pollution control system including: a denitration apparatus; an air heater; a precipitator; a desulfurization apparatus; a dehydrator; a spray drying apparatus provided with a spray unit that is configured to spray dehydrated filtrate as desulfurization wastewater supplied from the dehydrator; a flue gas introduction line through which a branch gas branched from the flue gas is introduced to the spray drying apparatus; a flue gas supply line through which flue gas returns to a main flue gas duct, the flue gas being obtained after the dehydrated filtrate is dried by the spray drying apparatus; and a powder supply apparatus that is configured to supply a powder to the flue gas introduction line.

A system to reduce standby losses in a hot water heater is presented. The system utilizes a dual safety relay valve between the combination gas controller and the burner. The dual safety relay valve bypasses gas to a rotary damper actuator valve to position a damper flapper valve located over/inside the flue pipe. Once the flapper valve has opened to ensure combustion, the gas is allowed to flow back to the dual safety relay valve. Some of the bypass gas may be diverted to boost the pilot or to supply a booster. The dual safety relay valve is then opened to allow the gas supply to the burner. Once the burner is turned off, bypass gas bleeds out of the rotary damper actuator valve to close the damper flapper valve to reduce standby losses through the flue pipe, and to allow the dual safety relay valve to close tightly.

There is provided an exhaust gas treatment apparatus. The exhaust gas treatment apparatus includes: a main discharge passage through which exhaust gas of combustion equipment is discharged; an heat exchanger between the combustion equipment and the main discharge passage; a nitrogen oxide decreasing device connected to the main discharge passage to decrease nitrogen oxides of exhaust gas; a bypass connected from the combustion equipment to the main discharge passage as a passage bypassing the heat exchanger to supply high temperature exhaust gas from the combustion equipment to the nitrogen oxide decreasing device; and a variable exhaust regulator disposed between the bypass and the main discharge passage to vary the amount of relatively high temperature exhaust gas flowing in the bypass and the amount of exhaust gas flowing in the main discharge passage in a correlated manner.

There is provided an exhaust gas treatment apparatus. The exhaust gas treatment apparatus includes: a main discharge passage through which exhaust gas of combustion equipment is discharged; an heat exchanger between the combustion equipment and the main discharge passage; a nitrogen oxide decreasing device connected to the main discharge passage to decrease nitrogen oxides of exhaust gas; a bypass connected from the combustion equipment to the main discharge passage as a passage bypassing the heat exchanger to supply high temperature exhaust gas from the combustion equipment to the nitrogen oxide decreasing device; and a variable exhaust regulator disposed between the bypass and the main discharge passage to vary the amount of relatively high temperature exhaust gas flowing in the bypass and the amount of exhaust gas flowing in the main discharge passage in a correlated manner.

A system for operating a damper comprises a flue pipe assembly, and a damper movable between an open position and a closed position within the flue pipe assembly. At least one thermoelectric generator is coupled to a surface of the flue pipe assembly. Operation of the damper is achieved by the thermoelectric generator harvesting thermal energy from the flue pipe assembly and converting it into usable electrical energy for actuation of the damper.

A system for operating a damper comprises a flue pipe assembly, and a damper movable between an open position and a closed position within the flue pipe assembly. At least one thermoelectric generator is coupled to a surface of the flue pipe assembly. Operation of the damper is achieved by the thermoelectric generator harvesting thermal energy from the flue pipe assembly and converting it into usable electrical energy for actuation of the damper.