Coal fired boiler plant and coal drying method for coal fired boiler plant

Patent metadata

Field	Value
Publication number	US-9360211-B2
Application number	US-201213613635-A
Country	US
Kind code	B2
Filing date	Sep 13, 2012
Priority date	Sep 13, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

Coal is properly dried and the efficiency of a boiler is increased while suppressing any reduction in efficiency of the boiler and the generation of hydrocarbon gas components. Employed are a coal dryer that dries coal, a boiler in which the coal that is dried in the coal dryer is mixed with air for combustion and burned, an air heater that heats the air for combustion that is supplied to the boiler using combustion exhaust gas discharged from the boiler, a precipitator that collects dust included in the combustion exhaust gas, a desulfurization plant that performs a desulfurization process on the combustion exhaust gas, and heat recovery equipment that heats a heating medium using the combustion exhaust gas. The coal dryer dries the coal using the heat energy of the heating medium that has been heated in the heat recovery equipment.

First claim

The invention claimed is:

1. A coal fired boiler plant, comprising:
a coal dryer that dries coal;
a boiler in which the coal that was dried in the coal dryer is mixed with air for combustion and burned;
an air heater that heats the air for combustion supplied to the boiler using combustion exhaust gas discharged from the boiler;
a precipitator that collects dust included in the combustion exhaust gas;
a desulfurization plant that performs a desulfurization process on the combustion exhaust gas;
heat recovery equipment that is provided on the downstream side of the air heater in the direction of flow of the combustion exhaust gas, and that heats a heating medium with the combustion exhaust gas,
a sensor that is provided on the downstream side of the heat recovery equipment in the direction of flow of the combustion exhaust gas, and that measures a temperature of the combustion exhaust gas on the outlet side of the heat recovery equipment,
a second air heater that heats carrier air supplied from the outside into the coal dryer using the heating medium that was heated in the heat recovery equipment, and
a third air heater that extracts a portion of steam which is generated by heating water with a heat energy obtained by burning the coal in the boiler and that further heats the carrier air using the portion of steam,
wherein the heat recovery equipment is connected to a first line through which the heating medium is fed into and a second line through which the heating medium is sent out,
wherein a bypass line is provided between the first line and the second line,
wherein control valves are provided on the bypass line and the first line, respectively,
wherein the sensor and the control valves are connected via a temperature controller,
wherein the coal dryer dries the coal using the heat energy of the heating medium that was heated in the heat recovery equipment,
wherein the carrier air heated by the second air heater and the third air heater dries the coal within the coal dryer,
wherein the temperature controller adjusts opening and closing and a degree of opening of the control valves, controls a quantity of the heating medium, and controls the temperature of the combustion exhaust gas from the heat recovery equipment, on the basis of the measurement results of the sensor; and
wherein the heating medium is water.

2. The coal fired boiler plant according to claim 1 , wherein the coal dryer dries the coal within the coal dryer by passing the heating medium that has been heated in the heat recovery equipment through a tubes provided within the coal dryer.

3. The coal fired boiler plant according to claim 1 , further comprising a heating medium heater that further heats the heating medium that has been heated in the heat recovery equipment using steam that has been extracted by extracting a portion of the steam generated by burning the coal in the boiler.

4. The coal fired boiler plant according to claim 1 , wherein the air heater heats air for drying supplied to the coal dryer using combustion exhaust gas discharged from the boiler, and
the coal dryer dries the coal within the coal dryer using the air for drying that is fed into the coal dryer.

5. The coal fired boiler plant according to claim 4 , wherein a portion of the air for combustion heated in the air heater is branched off and mixed with the carrier air that is supplied from the outside into the coal dryer, and supplied into the coal dryer.

6. The coal fired boiler plant according to claim 1 , wherein the desulfurization plant performs a desulfurization process by bringing the combustion exhaust gas into contact with process water, and
the coal fired boiler plant further comprises a spray dryer that evaporates wastewater obtained by separating a gypsum component from the process water after the desulfurization process, by bringing the wastewater into contact with the combustion exhaust gas on the upstream side of the desulfurization plant.

7. The coal fired boiler plant according to claim 1 , wherein the coal dryer feeds the exhaust gas from the coal dryer to the precipitator.

8. The coal fired boiler plant according to claim 1 , further comprising a fine coal recovery plant that recovers fine coal smaller than a predetermined particle size from the coal that is included in the exhaust gas from the coal dryer, and
the fine coal recovery plant supplies the recovered fine coal to the boiler together with the coal that has been dried in the coal dryer.

9. The coal fired boiler plant according to claim 8 , wherein the exhaust gas from which the fine coal has been removed by recovering the fine coal in the fine coal recovery plant is fed to the precipitator.

10. The coal fired boiler plant according to claim 1 , wherein the heat recovery equipment is disposed on the upstream side of the precipitator.

11. The coal fired boiler plant according to claim 1 , wherein the heat recovery equipment is disposed on the downstream side of the precipitator.

12. A method of drying coal that is supplied to a boiler in the coal fired boiler plant according to claim 1 , comprising:
heating a heating medium recovered in heat recovery equipment that is provided on the downstream side of an air heater in the direction of flow of combustion exhaust gas using the heat energy of combustion exhaust gas that is discharged from a boiler as a result of combustion of the coal in the boiler; and
drying the coal supplied to the boiler using the heat energy of the heating medium.

Assignees

• Sugita Satoru
• Honjo Shintaro
• Okamoto Takuya
• Mitsubishi Heavy Ind Ltd

Inventors

• Sugita Satoru
• Honjo Shintaro
• Okamoto Takuya

Classifications

• F23J15/022

  for removing solid particulate material from the gasflow · CPC title

• F23K1/04

  Heating fuel prior to delivery to combustion apparatus · CPC title

• F23L15/04 Primary

  Arrangements of recuperators · CPC title

• F23J15/04

  using washing fluids {(scrubbers for removing solids only F23J15/022)} · CPC title

• F23K2201/10

  Pulverizing · CPC title