Oxyfuel Combustion Boiler Plant and Operating Method for the Same

• US 20100212555A1
• Filed: 02/18/2010
• Published: 08/26/2010
• Est. Priority Date: 02/25/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Power Limited (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: YAMADA, Akihiro, Shibata, Tsuyoshi, Hayashi, Yoshiharu
• Granted Patent: US 8,561,555 B2
• Time in Patent Office: Days
• US Class Current: 110/186
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F23C 2202/00 Fluegas recirculation
• CPC Class Codes: F23C 2202/50 Control of recirculation rate
• CPC Class Codes: F23C 9/003 for pulverulent fuel for fluidized bed F23C10/02
• CPC Class Codes: F23C 9/08 for reducing temperature in combustion chamber, e.g. for protecting walls of combustion chamber
• CPC Class Codes: F23L 2900/07001 Injecting synthetic air, i.e. a combustion supporting mixture made of pure oxygen and an inert gas, e.g. nitrogen or recycled fumes
• CPC Class Codes: F23L 7/007 Supplying oxygen or oxygen-enriched air
• CPC Class Codes: F23N 2227/02 Starting or ignition cycles
• CPC Class Codes: F23N 2237/04 at two or more different localities
• CPC Class Codes: F23N 2241/10 Generating vapour
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 20/32 Direct CO2 mitigation
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

An oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

• • an exhaust gas supply pipe for supplying exhaust gas discharged from the first boiler to a burner of the second boiler, and a gas flow rate control apparatus for controlling a flow rate of exhaust gas flowing through the exhaust gas supply pipe.

Claims

1. An oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

an exhaust gas supply pipe for supplying exhaust gas discharged from the first boiler to a burner of the second boiler, and

a gas flow rate control apparatus for controlling a flow rate of exhaust gas flowing through the exhaust gas supply pipe.

2. An oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

an exhaust gas supply pipe for supplying exhaust gas discharged from the first boiler to a burner of the second boiler,

an exhaust gas circulation system for recirculating exhaust gas discharged from the second boiler to the burner of the second boiler,

a gas flow rate control apparatus for controlling an exhaust gas flow rate flowing into the second boiler, and

a switching unit for controlling a flow rate of exhaust gas flowing through the exhaust gas supply pipe and the exhaust gas circulation system based on a flow rate of exhaust gas calculated by the gas flow rate control apparatus.

3. An oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

an exhaust gas supply pipe for supplying exhaust gas discharged from the first boiler to a burner of the second boiler,

an exhaust gas circulation system for recirculating exhaust gas discharged from the second boiler to the burner of the second boiler,

a gas flow rate control apparatus for controlling an exhaust gas flow rate flowing into the second boiler, and

a switching unit for permitting the second boiler to use the exhaust gas of the first boiler supplied from the exhaust gas supply pipe when starting the second boiler and after arrival at a predetermined load condition of the boiler, reducing an exhaust gas quantity of the first boiler and increasing a circulation exhaust gas quantity of the second boiler.

4. An oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

an air quality control system for removing harmful components from exhaust gas discharged from the first boiler,

an exhaust gas supply pipe for supplying exhaust gas discharged from the air quality control system to a burner of the second boiler,

an exhaust gas circulation system for recirculating exhaust gas discharged from the second boiler to the burner of the second boiler,

a gas flow rate control apparatus for controlling an exhaust gas flow rate flowing into the second boiler, and

a switching unit for permitting the second boiler to use the exhaust gas of the first boiler supplied from the exhaust gas supply pipe when starting the second boiler and after arrival at a predetermined load condition of the boiler, reducing an exhaust gas quantity of the first boiler and increasing a circulation exhaust gas quantity of the second boiler.

5. The oxyfuel combustion boiler plant according to claim 4, wherein:

the gas flow rate control apparatus calculates a total exhaust gas quantity obtained by adding an exhaust gas quantity necessary for the operation condition of the second boiler to an exhaust gas quantity necessary for the load demand of the first boiler and controls an exhaust gas flow rate flowing into the second boiler on the basis of the total exhaust gas quantity.

6. The oxyfuel combustion boiler plant according to claim 4, wherein:

the gas flow rate control apparatus calculates a total exhaust gas quantity obtained by adding an exhaust gas quantity necessary for the operation condition of the second boiler to an exhaust gas quantity necessary for the load demand of the first boiler and controls an exhaust gas flow rate flowing into the second boiler on the basis of the oxygen concentration in the mixed gas of the oxygen and exhaust gas injected from the burner of the second boiler.

7. An operating method of an oxyfuel combustion boiler plant having a first boiler and a second boiler for injecting gas including oxygen in higher concentration than that in the air, gas including carbon dioxide in higher concentration than that in the air, and fuel from a burner and generating steam by combustion gas in a furnace, respectively, comprising:

an exhaust gas supply pipe for supplying exhaust gas discharged from the first boiler to a burner of the second boiler,

an exhaust gas circulation system for recirculating exhaust gas discharged from the second boiler to the burner of the second boiler, and

a gas flow rate control apparatus for controlling an exhaust gas flow rate flowing into the second boiler, wherein;

when starting the second boiler, the exhaust gas of the first boiler supplied from the exhaust gas supply pipe is used, and after arrival at a predetermined load condition of the boiler, an exhaust gas quantity of the first boiler is reduced, and a circulation exhaust gas quantity of the second boiler is increased.