JP2011247553A - Oxygen combustion boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen combustion boiler improved in efficiency by recovering and utilizing heat of the air in a building and an exhaust gas discharged from the boiler.SOLUTION: This oxygen combustion boiler is configured by disposing an air duct for exhausting, including a turbine inside thereof, at an upper section of the building, disposing an opening/closing member at an air inlet of the air duct for exhausting, further disposing a temperature detector for detecting a temperature of the air in the building, and disposing a control device performing an operation for switching the boiler from air combustion to oxygen combustion. The control device allows the air in the building to be exhausted to the air duct for exhausting on the basis of the air temperature detected by the temperature detector, and the power generation turbine disposed in the air duct for exhausting, is allowed to generate power by the exhaust of the air, thus the exhaust heat in the building can be effectively utilized.

Description

  The present invention relates to an elementary combustion boiler that efficiently recovers exhaust heat from a boiler, and more particularly to an oxyfuel boiler that can perform air combustion and oxyfuel combustion and efficiently recover the exhaust heat of a boiler.

  Thermal power generation systems currently play an important role as a stable power supply for the world's power energy. Oil, natural gas, and coal are used as fuels for thermal power generation, and especially coal has a large amount of minable reserves and is expected to grow in the future.

However, coal-fired power generation has a serious problem that the unit cost of CO ₂ emission is larger than that of oil and natural gas. Therefore, reducing the amount of CO ₂ emitted from the coal-fired power generation system into the atmosphere is an important issue in preventing global warming.

Therefore, a number of means for significantly reducing the amount of CO ₂ emitted from the coal-fired power generation system have already been proposed. Among them, the oxyfuel boiler system is being developed worldwide as one of the promising methods for separating and removing CO ₂ generated in a large amount in combustion exhaust gas with high efficiency.
Conventional coal-fired boilers use air as a combustion gas for the combustion of fuel coal, and most of the combustion exhaust gas is nitrogen gas. Therefore, the CO ₂ concentration in the combustion exhaust gas is low, and it is difficult to separate and recover CO ₂ from this exhaust gas.

  Therefore, in an oxyfuel boiler such as that described in Japanese Patent Application Laid-Open No. 2007-147162, a part of combustion exhaust gas treated with exhaust gas is mixed with high-purity oxygen generated by an oxygen production apparatus, and the oxygen concentration is adjusted. Is used as a combustion support gas for burning coal.

Therefore, the CO ₂ concentration in the exhaust gas is higher than that in air combustion, and CO ₂ can be easily separated and recovered from the exhaust gas.

  By the way, in an air combustion boiler, efficiency improvement is an important subject in order to reduce an environmental load. Therefore, a method for recovering energy from a medium having a low temperature has been proposed. For example, in order to use exhaust heat in a building in which a boiler is housed, air in the building is taken in and used as a combustion support gas for burning fuel in the boiler.

  In addition, as described in Japanese Patent Application Laid-Open No. 2004-251125, in the steam turbine equipment of a thermal power plant, steam that has worked in the steam turbine is exhausted to a condenser, and this condenser has a heat pump. Since the liquid carbon dioxide, which is a refrigerant, circulates, the steam exhausted by the condenser is heat-exchanged with the liquid carbon dioxide, and the exhaust heat of the steam is recovered and heat is expanded by the expander. There has also been proposed an exhaust heat recovery system configured to supply and cool liquid carbon dioxide having a reduced temperature to a condenser.

JP 2007-147162 A JP 2004-251125 A

  In the air-fired boiler described above, as the combustion support gas for burning the fuel in the boiler, the air in the upper part of the building containing the boiler is sucked by a fan, and the temperature is raised by exchanging heat with the exhaust gas discharged from the furnace. Is supplied into the furnace from the burner section and after-airport section provided in the furnace.

  By the way, in an oxyfuel boiler employing exhaust gas recirculation as disclosed in JP 2007-147162 A, the exhaust gas discharged from the boiler is recirculated to the boiler and mixed with oxygen produced by an oxygen production apparatus. Since the mixed gas is used as a combustion support gas during the oxygen combustion of the fuel, the air in the building in which the boiler is housed is not circulated to the boiler.

  However, in order to circulate or ventilate the air in the building, simply ventilating the air will throw away a large amount of exhaust heat from the boiler, resulting in boiler efficiency (ratio of the amount of heat used to the amount of heat input). ).

  An object of the present invention is to provide an oxyfuel boiler that improves the efficiency by recovering and using the air in the building and the heat of the exhaust gas discharged from the boiler.

  The oxyfuel boiler of the present invention is a boiler that generates steam using combustion gas generated by burning fuel as a heat source, and a furnace that constitutes the boiler is an air combustion that burns fuel and air, and a carbon dioxide that is discharged from the furnace. In an oxyfuel combustion boiler capable of both oxyfuel combustion in which fuel is combusted with combustion support gas formed by mixing exhaust gas mainly composed of carbon and oxygen, the boiler is housed in a building that houses the furnace furnace. An air duct having an air intake port for air to be supplied to the air is disposed, and heat supplied from the exhaust gas discharged from the furnace to the downstream side of the air duct is used as a heat source to raise the temperature of the air supplied to the boiler. An exchanger is provided, and a circulation gas duct for guiding a part of the exhaust gas discharged from the furnace is connected to an air duct on the upstream side of the heat exchanger so as to be separated from the air. An oxygen production device that produces oxygen is installed, and when the boiler is subjected to oxygen combustion, oxygen is produced by the oxygen production device and exhaust gas introduced by the circulation gas duct is supplied to the furnace to supply fuel. An exhaust air duct with a turbine inside is installed at the top of the building, and an open / close member is installed at the air intake of the exhaust air duct to detect the air temperature in the building. A temperature detector is installed, and a control device for switching the boiler from air combustion to oxyfuel combustion is installed, and the air in the building is exhausted based on the temperature of the air detected by the temperature detector by the control device. The flow rate of the air exhausted through the air duct is adjusted, and the flow rate of the air flowing down the air duct and supplied to the heat exchanger and the flow rate of the exhaust gas supplied through the circulation gas duct are adjusted. And adjusting, respectively.

  Further, the oxyfuel boiler of the present invention is a boiler that generates steam using combustion gas generated by burning fuel as a heat source, and the furnace constituting the boiler is air combustion for burning fuel and air, and discharged from the furnace. In an oxyfuel combustion boiler capable of both oxyfuel combustion in which fuel is combusted with combustion-supporting gas formed by mixing exhaust gas mainly composed of carbon dioxide and oxygen, in the building that houses the furnace of the boiler, An air duct having an air intake port for air to be supplied to the boiler is disposed, and the temperature of the air supplied through the air duct is raised and supplied to the boiler using the exhaust gas discharged from the furnace as a heat source downstream of the air duct. A heat exchanger is provided, and a circulation gas duct for guiding a part of the exhaust gas discharged from the furnace is connected to the air duct on the downstream side of the heat exchanger so as to be separated from the air. An oxygen production device that produces oxygen is installed and fuel is supplied by supplying a combustion-supporting gas, which is a mixture of the oxygen produced by the oxygen production device and the exhaust gas introduced by the circulation gas duct, when the boiler is oxygen-burned to the furnace. A temperature detector that detects the temperature of the air in the building by installing a heat pump that uses air guided through a branch pipe branched from an air duct on the downstream side of the heat exchanger as a heat source And installing a control device for switching the boiler from air combustion to oxyfuel combustion, and controlling the flow rate of air supplied to the heat pump through the branch pipe based on the temperature of the air detected by the temperature detector by the control device. Adjusting the flow rate of air supplied to the heat exchanger by flowing down the air duct and the flow rate of exhaust gas supplied through the circulating gas duct, respectively. And features.

  Further, the oxyfuel boiler of the present invention is a boiler that generates steam using combustion gas generated by burning fuel as a heat source, and the furnace constituting the boiler is air combustion for burning fuel and air, and discharged from the furnace. In an oxyfuel combustion boiler capable of both oxyfuel combustion in which fuel is combusted with combustion-supporting gas formed by mixing exhaust gas mainly composed of carbon dioxide and oxygen, in the building that houses the furnace of the boiler, An air duct having an air intake port for air to be supplied to the boiler is disposed, and the temperature of the air supplied through the air duct is raised and supplied to the boiler using the exhaust gas discharged from the furnace as a heat source downstream of the air duct. A heat exchanger is provided, and a circulation gas duct for guiding a part of the exhaust gas discharged from the furnace is connected to the heat exchanger, and the circulation is connected to an air duct on the downstream side of the heat exchanger. An oxygen production device is installed so that the gas duct is connected to produce oxygen separated from the air, and the oxygen produced by the oxygen production device and the exhaust gas introduced by the circulating gas duct are used when the boiler is subjected to oxygen combustion. The mixed support gas is supplied to the furnace to burn the fuel, and a heat pump is installed with the air led through the branch pipe branched from the air duct on the downstream side of the heat exchanger as the heat source, A temperature detector that detects the temperature of the air is installed in the building, a control device that performs an operation of switching the boiler from air combustion to oxygen combustion is installed, and the temperature of the air detected by the temperature detector is detected by the control device. The flow rate of air supplied to the heat pump through the branch pipe is adjusted based on the flow rate, the flow rate of air supplied to the heat exchanger through the air duct, and the circulation gas duct. And adjusting each flow rate of the exhaust gas supplied Te.

  ADVANTAGE OF THE INVENTION According to this invention, the oxyfuel boiler which collect | recovered and utilized the heat | fever of the exhaust gas discharged | emitted from the air in a building and a boiler, and the improvement of efficiency is realizable.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the oxyfuel boiler which is 1st Example of this invention. The schematic of the control system used for control of the oxyfuel boiler of 1st Example shown in FIG. The schematic block diagram of the oxyfuel boiler which is 2nd Example of this invention. The schematic of the control system used for control of the oxyfuel boiler of 2nd Example shown in FIG. The schematic block diagram of the oxyfuel boiler which is 3rd Example of this invention. The schematic of the control system used for control of the oxyfuel boiler of 3rd Example shown in FIG. FIG. 6 is a schematic view of a power plant system including a steam turbine and a heat pump installed in the oxyfuel boiler of each embodiment of the present invention shown in FIGS. 1, 3, and 5.

  An oxyfuel boiler that is an embodiment of the present invention will be described below with reference to the drawings.

An oxyfuel boiler as a first embodiment in which the present invention is applied to a coal fired boiler will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing the configuration of an oxyfuel boiler according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram of a control system for controlling the oxyfuel boiler according to the embodiment of FIG.
The oxyfuel boiler of the present embodiment shown in FIGS. 1 and 2 is a boiler that can be used by switching from air combustion to oxyfuel combustion.

  The oxyfuel boiler of the present embodiment includes a boiler building 1 that houses therein a furnace 2 that constitutes the boiler, and fuel 8 and oxygen 19 are blown into the furnace 2 on the wall surface of the furnace 2 and burned for combustion. A burner unit 102 that generates gas 16 and an after-air port unit 101 that supplies after-air for two-stage combustion are installed.

  In the furnace 2, a superheater 112, a reheater 113, and a economizer 114 that heat the steam in the water pipe by the combustion gas 16 generated in the furnace are along the flow direction of the combustion gas flowing down in the furnace 2. Are installed sequentially.

  Around the boiler building 1 are installed a coal supply device 3 for pulverizing fuel coal and supplying it to a burner unit 102 provided in the furnace, and an oxygen production device 13 for supplying combustion oxygen 19 from which oxygen is separated from air. Has been.

  An exhaust gas duct 11 is disposed at the outlet of the furnace 2 to discharge the combustion gas 16 whose temperature has been lowered by heat exchange as the exhaust gas 18, and denitration is performed upstream of the exhaust gas duct 11 to remove NOx in the exhaust gas 18. On the downstream side of the apparatus 4, heat exchangers 100 using the exhaust gas 18 flowing down as a heat source are installed.

  A part of the exhaust gas 18 discharged from the furnace 2 is introduced into the building 1 as a combustion supporting gas for burning the fuel when the boiler is switched from the air combustion system to the oxyfuel combustion system. A circulation air duct 10 is provided to supply the air.

  At the start of the boiler that is burned by the air combustion method, the air 14 in the building 1 is supplied from the air intake port 111a provided at the tip of the circulation air duct 10 disposed in the upper part of the building 1. After the temperature of the introduced air 14 is raised by the heat exchanger 100 using the exhaust gas 18 as a heat source, the burner portion 102 and the after-air port provided in the furnace 2 from the heat exchanger 10 through the circulation air duct 10a. The heated air 14 is supplied to the unit 101 as a combustion support gas when the boiler is burned by the air combustion method. The circulation air duct 10 is provided with a fan 103 for sucking combustion supporting gas.

  As a device for purifying the exhaust gas 18 discharged from the furnace 2, the exhaust gas duct 11 on the downstream side of the denitration device 4 that removes NOx in the exhaust gas 18 is supplied with the dedusting device 5 and the SOx in the exhaust gas 18. The desulfurization device 6 to be removed is sequentially installed, and the exhaust gas 18 flowing down the desulfurization device 6 is released from the chimney 7 into the atmosphere.

Some of the exhaust gas 18 flowing down the desulfurizer 6, is supplied by branching the exhaust gas duct 11 to the CO ₂ recovery facility 9, and separating and recovering CO ₂ in the flue gas 18 at the CO ₂ recovery facility 9 Yes.

  A part of the exhaust gas 18 branched from the exhaust gas duct 11 located between the dust removing device 5 and the sulfur device 6 and passed through the dust removing device 5 is used as a combustion support gas when the boiler is burned in an oxyfuel combustion system. For this purpose, a circulating gas duct 12 connected to the circulating air duct 10 and recirculated to the boiler is provided.

  The circulation air duct 10 is provided with an air adjustment damper 104a for adjusting the composition of the combustion gas at the upstream position where the circulation gas duct 12 is connected. The circulating gas duct 12 is also provided with an air conditioning damper 104b for adjusting the composition of the combustion gas.

  An exhaust air duct 107 for exhausting the air in the building 1 is installed in the upper part of the building 1, and the interior of the exhaust air duct 107 is used for power generation using the energy of the exhausted air. A turbine 106 is installed, and an opening / closing plate 108 that controls opening and closing of the exhaust air duct 107 is installed at an air intake port 111 b of the exhaust air duct 107.

A circulation air duct 10 disposed in the upper part of the building 1 is provided with a temperature sensor 110 for detecting the temperature of air in the building 1 introduced into the circulation air duct 10. A CO ₂ sensor 109 for detecting the concentration of CO ₂ in the air in the building 1 is installed at the top of the building 1.

In the oxyfuel boiler of the present embodiment, a control device 15 for operating each operation device of the oxyfuel boiler is installed, and the temperature and air of the air in the building 1 detected by the temperature sensor 110 and the CO ₂ sensor 109 are installed. The operation of the oxyfuel boiler of this embodiment is controlled by controlling the control device 15 based on the concentration of CO _{2 in} the engine to switch from the air combustion system to the oxyfuel combustion system.

  The details of the control system by the control device 15 are shown in FIG. 2, but the opening degree of the damper 104a provided in the circulation air duct 10 and the circulation gas duct 12 are provided by the operation signal from the control device 15. The opening degree of the damper 104b is controlled, and the suction force of the fan 103 provided in the circulation air duct 10 is controlled.

  The control device 15 controls the operation of the oxygen production facility 13 and also controls the opening degree of the opening / closing plate 108 provided in the air intake port 111 b of the exhaust air duct 107.

In the control system by the control device 115, as shown in FIG. 2, the control device 115 includes a controller 116 that calculates operation signals to be output to various operation devices, and switches the operation of the boiler from the air combustion method to the oxyfuel combustion method. At this time, based on the detected value of the air temperature introduced into the circulating air duct 10 detected by the temperature sensor 110 and the detected value of the CO ₂ concentration in the building 1 detected by the CO ₂ sensor 109, the controller 116, the controller 116 calculates and outputs optimum operation signals for various operation devices, and adjusts the opening degrees of the dampers 104a and 104b, which are various operation devices, adjusts the opening amounts of the opening and closing plates 108, and produces oxygen. It functions to output each operation signal for controlling the operation of the device 13 and the operation of the fan 103.

  That is, in the control system of the control device 115, the detected value of the air temperature in the building 1 detected by the temperature sensor 110 provided in the vicinity of the air intake port 111b of the exhaust air duct 107 is the air temperature during normal operation. When the temperature rises above 50 ° C. to 60 ° C. and rises to a high temperature of, for example, 70 ° C. to 80 ° C., the controller 116 of the control device 115 calculates and outputs the temperature based on the detected temperature of the temperature sensor 110. By opening the opening / closing plate 108 of the air intake port 111b of the exhaust air duct 107 provided in the building 1 according to the operation signal and discharging the air in the building 1 to the outside of the building 1 through the exhaust air duct 107, The air in 1 is ventilated and the temperature of the air in the building is lowered to 50 ° C. to 60 ° C., which is a normal air temperature.

Similarly, in the control system of the control device 115, in the air in the building 1 detected by the CO ₂ sensor 109 provided near the air intake port 111b of the exhaust air duct 107 installed in the upper part of the building 1. CO detection value of the ₂ concentrations, when higher than about 1% of the CO ₂ concentration of CO ₂ concentration set value is computed in the controller 116 of the control device 115 based on the detected concentration of CO ₂ sensor 109 The opening of the opening / closing plate 108 provided at the air intake port 111b of the exhaust air duct 107 is opened by the operation signal output in this manner, and the air in the building 1 is discharged out of the building 1 through the exhaust air duct 107, and is lowered until the CO ₂ concentration of less than about 1% by ventilating air is CO ₂ concentration without risk of CO ₂ concentration in the operator of the air in the building of the building 1.

  At the same time, the operation of the oxygen production device 13 is stopped by the operation signal output from the controller 116 of the control device 115, and the damper 104a provided in the circulation air duct 10 and the damper 104b provided in the circulation gas duct 12 are closed. The operation of the oxyfuel boiler can be stopped by stopping the supply of the combustion support gas supplied to the after-airport portion 101 and the burner portion 102 of the furnace 2.

  Further, in the control system of the control device 115, the temperature of the air in the building 1 is detected by the temperature sensor 110 provided in the circulation air duct 10 disposed in the upper part of the building 1. By switching from the combustion method to the oxyfuel combustion method, when the temperature of the air in the building 1 rises above a predetermined temperature, an operation signal that is output based on the deviation temperature that is compared with the temperature set value by the controller 116 It is possible to increase the output of the fan 103 and increase the ventilation amount of the air 14 introduced into the circulation air duct 10.

  Next, the control method of the oxyfuel boiler by the control device 15 installed in the oxyfuel boiler of the present embodiment will be described in detail below.

  In the oxyfuel boiler and control device 15 shown in FIG. 1 and FIG. 2, when the operation of the boiler that operates the boiler by the air combustion method is started, it is calculated and output by the controller 116 constituting the control system of the control device 115. The damper 104a of the circulation air duct 10 is fully opened by the operation signal, and the open / close plates 108 provided at the damper 104b of the circulation gas duct 12 and the air intake port 111b of the exhaust air duct 107 are fully closed, respectively. The coal is transported to the burner unit 102 and the after-air port unit 101 by air supplied from the air duct 10 via the air ducts 10a and 10b, and the boiler is operated by an air combustion method in which the fuel is burned with air in the furnace 2. To do.

When coal is combusted by air supplied into the furnace 2 with a boiler operating in this air combustion system, the exhaust gas 18 discharged from the outlet of the furnace 2 contains NOx, SOx, CO ₂ , water vapor, and the like. As described above, the exhaust gas 18 is subjected to exhaust gas treatment by the denitration device 4, the dust removal device 5, and the desulfurization device 6, and released from the chimney 7 into the atmosphere.

  When the heat recovery of the furnace 2 that operates the boiler by the air combustion method is stabilized, the operation of the boiler is switched from the air combustion method to the oxyfuel combustion method and switched to the oxyfuel boiler operation. Oxygen 19 produced by being separated from air by the oxygen production facility 13 based on the operation by the apparatus 115 is gradually taken into the furnace 2 to burn the coal of fuel.

  At this time, the damper 104a provided in the circulation air duct 10 for taking in air to supply the air in the building 1 to the furnace 2 was closed by the operation by the controller 106 of the control device 115, and was discharged from the furnace 2. In order to supply the exhaust gas 18 to the furnace 2, the damper 104 b provided in the circulating gas duct 12 that takes in part of the exhaust gas 18 is opened, and the operation of the suction fan 103 is increased to produce oxygen and the exhaust gas 18 that is taken into the circulating gas duct 12. Combustion gas 20 is formed by mixing with oxygen 19 produced by equipment 13, and this combustion support gas 20 is conveyed to burner portion 102 and after-airport portion 101 of furnace 2, and fuel coal is burned in furnace 2. As a result, the boiler is switched from the air combustion system to the oxyfuel combustion operation.

  The combustion support gas 20 for burning the coal of fuel supplied to the oxyfuel boiler operated by the oxyfuel combustion system is formed as follows.

  The combustion gas 16 generated by burning the fuel in the furnace 2 is used as a heat source for the heater 112, the reheater 113, and the economizer 113 and then discharged as exhaust gas 18 from the outlet of the furnace 2 through the exhaust gas duct 11. However, the circulation gas duct 12 branched from the exhaust gas duct 11 and leading to the exhaust gas 18 is connected to the circulation air duct 10 on the upstream side of the heat exchanger 100.

Therefore, the exhaust gas 18 mainly composed of CO ₂ flowing down through the circulation gas duct 12 is sucked by the fan 103 provided in the circulation air duct 10 and from the circulation gas duct 12 through the circulation air duct 10 and the circulation air duct 10a. 2 is supplied to the after-airport unit 101 and the burner unit 102 and recirculated to the furnace 2.

Then, oxygen separated from the air by the oxygen production apparatus 13 is supplied to the circulation air duct 10a, and the exhaust gas 18 mainly composed of CO ₂ flowing down the circulation air duct 10a via the oxygen and the circulation duct 12; Are mixed in the circulation air duct 10a to form the support gas 20, and the support gas 20 is supplied to the burner portion 102 and the after-airport portion 101 of the furnace 2 to burn the fuel by the oxyfuel combustion method. Used as supporting gas 20 for oxyfuel boilers.

Although not shown, the exhaust gas 18 used for forming the combustion supporting gas 20 is exhaust gas after dedusting with the dust collector 5 or exhaust gas after desulfurizing with the desulfurizer 6. May be.
The suction fan 103 provided in the circulation air duct 10 is installed on the upstream side of the heat exchanger 100, and the circulation gas duct 12 branched from the exhaust gas duct 11 is upstream of the suction fan 103 and downstream of the damper 104a. It is connected with the circulation air duct 10 at the position.

Next, the contents of the control method based on the temperature of the air in the building and the concentration of CO ₂ in the air in the oxyfuel boiler of the present embodiment that operates in the oxyfuel combustion system will be described.

  When operating the oxyfuel boiler of this embodiment in the oxyfuel combustion system, the air temperature in the building 1 rises to 50 ° C to 60 ° C, but the operation of the boiler was switched from the air combustion system to the oxyfuel combustion system. In this case, since the intake of the air supplied to the furnace 2 is not performed, the temperature of the air in the building 1 further rises to about 70 ° C. or higher.

  Therefore, when the boiler is operated by switching to the oxyfuel combustion method, the temperature of the air 14 in the building 1 detected by the temperature sensor 110 is input to the control device 15, and the temperature is set by the controller 116 provided in the control device 15. The value (about 70 ° C.) is compared with the temperature detection value of the temperature sensor 110, and when the air temperature in the building 1 rises above the temperature set value, the exhaust air duct 107 is based on the deviation temperature between the two. The opening / closing plate 108 provided in the air intake port 111b is opened to exhaust the heated air 14 in the building 1 to the outside through the exhaust air duct 107 to set the temperature of the air in the building 1 to a predetermined temperature. Control to maintain less than value (about 70 ° C.).

  The air 14 in the building 1 whose temperature has been raised is taken into the exhaust air duct 107 from the air intake port 111b by the control device 15, whereby the power generation turbine 106 installed in the exhaust air duct 107 is rotated to rotate the building 1. The energy of the air 14 inside is converted into electric energy and recovered to improve the efficiency of the boiler. According to the trial calculation, it becomes possible to improve the efficiency of the entire boiler by about 0.1%.

In the above-described oxyfuel boiler of the present embodiment, detailed description is omitted,
Not only can the oxyfuel boiler improve the efficiency by effectively recovering the heat of the exhaust air exhausted from the air and the boiler in the building, but it can also be used even if CO ₂ leaks from the piping that recirculates the exhaust gas. It can be avoided that the building housed in is filled with CO ₂ .

In other words, in the above embodiment, the heat of the air 14 in the building 1 and the exhaust gas 18 discharged from the furnace 2 that is not used during fuel combustion in oxyfuel combustion can be effectively recovered, and the boiler efficiency can be improved. Moreover, since the air in the building 1 can be ventilated, it is possible to prevent danger when CO ₂ leaks into the building 1 due to some factor.

Also, when the CO ₂ concentration in the air in the building 1 increases due to some factor, the CO in the air in the building 1 detected by the CO ₂ sensor 109 is detected as in the previous control of the air temperature in the building 1. by the controller 116 provided in the control unit 15 based on the ₂ concentration, CO ₂ concentration of the setpoint (CO ₂ concentration of 1%) is compared with the CO ₂ concentration detection value of Toko of CO ₂ sensor 109, building 1 When the CO ₂ concentration in the air rises above the CO ₂ concentration set value, the opening / closing plate 108 provided at the air intake port 111b of the exhaust air duct 107 is opened based on the deviation concentration between the two and the building 1 The heated air 14 in the inside is exhausted to the outside through the exhaust air duct 107, and the temperature of the air in the building 1 is controlled to be kept below a predetermined CO ₂ concentration set value (CO ₂ concentration 1%). .

  Next, a thermal power generation system including a steam turbine driven by steam generated by the oxyfuel boiler of this embodiment will be described with reference to FIG.

  The thermal power generation system provided with the steam turbine plant and the heat pump shown in FIG. 7 is not only the oxyfuel boiler of the first embodiment shown in FIG. 1, but also the second and third shown in FIGS. 3 and 5 to be described later. It is the thermal power generation system installed in the oxyfuel boiler of each Example.

  The steam turbine plant 120 of the thermal power generation system shown in FIG. 7 is driven by steam generated by the oxyfuel boiler 1, and the heat pump 15 uses the air exhausted from the oxyfuel boiler building 1 as a heating medium. Is shown.

  In the thermal power generation system including the steam turbine plant 120 and the heat pump 15 shown in FIG. 7, a furnace 2 is installed inside the building 1 of the oxyfuel boiler, and steam supplied to the steam turbine of the thermal power generation system in the furnace 2. Are provided with a superheater 112, a reheater 113, and a economizer 114.

  The steam turbine plant 120 of the thermal power generation system installed in the oxyfuel boiler is a high-pressure steam turbine 120a driven by steam generated in the superheater 112 of the furnace 2, and steam reheated by the reheater 113 of the furnace 2. The middle / low pressure steam turbine 120b driven by the turbine, the generators 121a and 121b that generate electric power using the rotational force of the turbine, and the condensate that cools the steam discharged from the middle / low pressure steam turbine 120b to condensate The water supply pump 123 which supplies the condensate of the condenser 122 and the condenser 122 to the economizer 114 is provided.

  Further, the thermal power generation system is provided with a heat pump 15 that heats the condensate that has been condensed by the condenser 122 of the steam turbine plant 120.

  The heat pump 15 of the thermal power generation system includes a heat exchanger 117a that heats the heat medium 21 by exchanging heat with air from a heat source exhausted from the building 1, and a compressor that compresses the heat medium heated by the heat exchanger 117a. 118, heat exchanger 117b that heat-exchanges the heat medium 21 compressed by the compressor 118 with condensate to raise the temperature of the condensate, and heat medium 21 that has been heat-exchanged by the heat exchanger 117b expands the temperature. And an expansion valve 119 for lowering the pressure.

  The air 14 exhausted from the boiler building 1 is guided to the heat exchanger 117a of the heat pump 15 as a heat source and supplies heat to the heat medium 21 of the heat pump 15.

  The heat medium 21 after the heat exchange is compressed by the compressor 118 and heated to 300 to 400 ° C. The heat of the heat medium 21 that has been heated is recovered from the feed water pump 123 through the heat exchanger 117b. Heat is exchanged with water to obtain steam having a steam temperature of 250 to 350 ° C. and supplied to the economizer 114 of the furnace 2.

  The steam temperature generated by heat exchange in the heat exchanger 117b is close to the temperature of steam (250 to 300 ° C.) after passing through the economizer 114 of a conventional boiler.

  Therefore, the heat consumed in the economizer 114 of the furnace 2 can be reduced by raising the temperature of the condensate downstream of the feed water pump 123 using the exhaust heat from the furnace 2 and the heat pump 15. That is, the thermal efficiency of the entire boiler can be increased.

As described above, in the above-described embodiment, not only can the oxyfuel boiler improve the efficiency by effectively recovering the air in the building and the heat of the exhaust gas discharged from the boiler, but also the piping for recirculating the exhaust gas Thus, even if CO ₂ leaks, it can be avoided that the building containing the boiler is filled with CO ₂ .

  According to this embodiment, it is possible to realize an oxyfuel boiler that improves the efficiency by recovering and using the air in the building and the heat of the exhaust gas discharged from the boiler.

An oxyfuel boiler as a second embodiment in which the present invention is applied to a coal fired boiler will be described with reference to FIGS. FIG. 3 is a schematic diagram showing the configuration of an oxyfuel boiler according to a second embodiment of the present invention, and FIG. 4 is a schematic diagram of a control system for controlling the oxyfuel boiler according to the embodiment of FIG.
The oxyfuel boiler of the present embodiment shown in FIGS. 3 and 4 is a boiler that can be used by switching from air combustion to oxyfuel combustion.

Since the basic configuration of the oxyfuel boiler of this embodiment is the same as that of the oxyfuel boiler of the first embodiment shown in FIGS. 1 and 2, the configuration common to both embodiments is omitted and is different. Only described below.
In the oxyfuel boiler of the present embodiment shown in FIGS. 3 and 4, the circulation gas duct 12 including the fan 103 b branched from the exhaust gas duct 11 and leading the exhaust gas 18 is used for circulation on the downstream side of the heat exchanger 100. Connected to the air duct 10.

Therefore, the exhaust gas 18 mainly composed of CO ₂ fed by the fan 13b of the circulating gas duct 12 is sent from the circulating gas duct 12 through the circulating air duct 10 and the circulating air duct 10a to the after air port portion 101 and the burner portion of the furnace 2. 102 is supplied to 102 and recirculated to the furnace 2.

Then, oxygen produced by separating from the air by the oxygen production device 13 is supplied to the circulation air duct 10a, and the exhaust gas 18 mainly composed of CO ₂ flowing down the circulation air duct 10a via the circulation duct 12. And the oxygen are mixed in the circulation air duct 10a to form a support gas 20 and supply it to the burner portion 102 and the after-airport portion 101 of the furnace 2 to burn the fuel by an oxyfuel combustion method. It is used as boiler combustion gas 20.

  In this embodiment, the exhaust air duct 107 installed at the upper part of the building 1, the power generation turbine 106, the air intake port 111 b of the power generation turbine 106 and the opening / closing plate 108 are not installed.

Furthermore, in this embodiment, the air conditioning damper 104 a installed in the circulation air duct 10 is disposed on the downstream side of the heat exchanger 100. A CO ₂ sensor 109 that detects CO ₂ in the air in the building 1 is installed in the vicinity of the air intake port 111 a at the tip of the circulation air duct 10.

  Then, the air heated by the exhaust gas 18 of the boiler in the heat exchanger 100 from the circulation air duct 10 on the downstream side of the heat exchanger 100 and the upstream side of the air conditioning damper 104a through the branch pipe 10e is used as a heat medium. The heat pump 15 supplied as is installed, and the exhaust heat of the exhaust gas from the boiler is reused by the heat pump 15.

  The details of the control system by the control device 115 installed in the oxyfuel boiler of the present embodiment are shown in FIG. 4, but when the control device 15 knows the control of the oxyfuel boiler switched to the oxyfuel combustion method, Not only is the amount of oxygen produced by controlling the operation of the oxygen production facility 13 controlled by the control device 115, but also the opening degree of the damper 104a provided in the circulation air duct 10 by the controller 16 of the control device 15. , And the amount of air supplied is controlled by controlling the opening degree of the damper 104c provided in the branch pipe 10e leading to the heat pump 15.

  Further, the controller 16 of the control device 115 controls the operation of the fan 103b provided in the circulation gas duct 12 that branches from the exhaust duct 11 and circulates a part of the exhaust gas to the boiler, and adjusts the suction force thereof. The operation of the fan 103a provided in the circulation air duct 10 is controlled to adjust the suction force.

In the control system by the controller 16 of the control device 115, as in the control by the controller 16 of the control device 115 of the first embodiment, the control device 115 includes dampers 104a and 104c, fans 103a, 103b, a controller 116 that calculates operation signals to be output to various operation devices such as the oxygen production apparatus 13, and detected by the temperature sensor 110 when the operation of the boiler is switched from the air combustion system to the oxyfuel combustion system. Based on the detected value of the air temperature introduced into the circulation air duct 10 and the detected value of the CO ₂ concentration in the air in the building 1 detected by the CO ₂ sensor 109, the controller 116 controls the various operating devices. Optimal operation signals are respectively calculated, and the dampers 104a and 104b, which are various operation devices, are provided from the controller 116. Opening, the operation of the air separation unit 13, and outputs the operation signal for controlling the operation of the fan 103b.

  When operating the oxyfuel boiler of this embodiment in the oxyfuel combustion system, the air temperature in the building 1 rises to 50 ° C to 60 ° C, but the operation of the boiler was switched from the air combustion system to the oxyfuel combustion system. In this case, since the intake of the air supplied to the furnace 2 is not performed, the temperature of the air in the building 1 further rises to about 70 ° C. or higher.

  Therefore, when the boiler is operated by switching to the oxyfuel combustion method, the temperature of the air 14 in the building 1 detected by the temperature sensor 110 is input to the control device 15, and the temperature is set by the controller 116 provided in the control device 15. The value (about 70 ° C.) is compared with the temperature detection value of the temperature sensor 110, and when the air temperature in the building 1 rises above the temperature set value, the circulating air duct 10 is based on the deviation temperature between the two. The output of the fan 103a provided in the building is increased, the damper 104a provided in the circulation air duct 10 is closed, the damper 104c provided in the branch pipe 104e is opened, and the heated air 14 in the building 1 is heated through the branch pipe 104e. 15 is supplied as a heat source, and the temperature of the air in the building 1 is controlled to be kept below a predetermined temperature set value (about 70 ° C.).

Also in the oxyfuel boiler of this embodiment, the detected value of the CO ₂ concentration detected by the CO ₂ sensor 109 by the controller 116 of the control device 115 is higher than the CO ₂ concentration of about 1% which is the set CO ₂ concentration. In this case, similar to the control by the temperature sensor 110 described above, the operation signals calculated by the controller 116 of the control device 115 are output based on the detected concentration of the CO ₂ sensor 109 to output the dampers 104a and 104c, the fan Each of 103a and 103b is operated to control the CO ₂ concentration in the air in the building 1 to be less than the CO ₂ concentration set value (about 1%).

  In the oxyfuel boiler of the present embodiment, the damper 104a provided in the circulation air duct 10 is fully opened by the control system by the control device 115 so that the boiler can be operated by an air combustion method at the start of the boiler operation, and the branch pipe. The opening of the damper 104c provided in 10e is operated to be fully closed, and coal as fuel is conveyed to the burner portion 102 and the after-airport portion 101 of the furnace 2 by air as a combustion support gas and burned.

  Next, when the heat recovery in the furnace 2 is stabilized, the oxygen production facility 13 is operated in accordance with the operation command of the control system by the controller 116 of the control device 115, and the oxygen 19 produced by the oxygen production facility 13 is gradually added to the combustion support gas. Into.

  When the operation of the boiler is shifted to the oxyfuel combustion method, the damper 104a provided in the circulation air duct 10 is closed and the fan 103b provided in the circulation gas duct 12 is opened by an operation command from the controller 116 of the control device 115. Then, a part of the exhaust gas 18 is supplied through the circulation gas duct 12 and the circulation air duct 10a and mixed with the oxygen 19 produced by the oxygen production facility 13 to form a combustion support gas for burning the fuel coal.

By transferring this combustion-supporting gas to the burner portion 102 and the after-airport portion 101 of the furnace 2 and burning them, the switching of the boiler from the air combustion method to the oxyfuel combustion method is completed.
At the time of oxyfuel combustion in which the boiler is burned by the oxyfuel combustion method, air 14 is not included in the combustion support gas, so that the ratio of CO _{2 in} the exhaust gas 16 is increased. Therefore, NO x removal apparatus 4, the whole or a part of the dedusting apparatus 5 and the exhaust gas treated exhaust gas 18 in the desulfurization device 6 was supplied to the CO ₂ recovery facility 9, the separation of CO ₂ of the exhaust gas 18 in the CO ₂ recovery facility 9 And CO ₂ is recovered.

  The circulation gas duct 12 is connected to the circulation air duct 10 on the downstream side of the heat exchanger 100. In addition, the circulating exhaust gas 17 flowing down the circulating gas duct 12 is branched into one that is directly led to the after-airport portion 101 and the burner portion 102 of the furnace 2 and one that is led to the fuel supply device 3.

  The circulating exhaust gas 17 supplied to the after-airport unit 101 and the burner unit 102 of the furnace 2 is mixed with the oxygen 19 supplied from the oxygen production device 13 before being led to the after-airport unit 101 and the burner unit 102 to burn the fuel. The supporting gas is formed.

  On the other hand, the air sucked by the fan 103a from the air intake port 111 of the circulation air duct 10 is guided to the heat pump 15 as the exhaust heat utilization device through the branch pipe 10e, and the exhaust gas 18 discharged from the furnace 2 by the heat pump 15. Use the exhaust heat of the water effectively.

Based on the detected value of the air temperature introduced into the circulating air duct 10 detected by the temperature sensor 110 and the detected value of the CO ₂ concentration in the building 1 detected by the CO ₂ sensor 109, the controller 116 Optimum operation signals for various operation devices are calculated and output, and the controller 116 adjusts the opening of the dampers 104a and 104c, which are the various operation devices, the operation of the oxygen production apparatus 13, and the operation of the fans 103a and 103b. It functions to output each operation signal that controls.

  That is, in the control system of the control device 115, the detected value of the air temperature in the building 1 detected by the temperature sensor 110 provided in the vicinity of the air intake port 111b of the exhaust air duct 107 is the air temperature during normal operation. When the temperature rises above 50 ° C. to 60 ° C. and rises to a high temperature of, for example, 70 ° C. to 80 ° C., the controller 116 of the control device 115 calculates and outputs the temperature based on the detected temperature of the temperature sensor 110. A temperature setting value (about 70 ° C.) is compared with the temperature detection value of the temperature sensor 110 by an operation signal, and when the air temperature in the building 1 rises above the temperature setting value, the temperature is set based on the deviation temperature between the two. The operation of the fan 103a provided in the circulation air duct 10 is increased, the damper 104a is fully closed, the damper 104c provided in the branch pipe 10e is opened, and the heated air 14 is heated. Introduced as a heat source to the amplifier 15, to recover the energy of the air 14.

By recovering the energy of the heated air 14 by the heat pump 15, in this embodiment, the efficiency of the entire boiler can be improved by about 0.1 to 0.3%.
In addition, although description is abbreviate | omitted in the present Example, it is that the thermal power generation system provided with the steam turbine plant and heat pump shown in FIG. 7 is installed in the boiler of a present Example, and the oxyfuel boiler of 1st Example. It is the same.

In the present embodiment described above, not only can an oxyfuel boiler that efficiently recovers the heat of exhaust gas discharged from the air and boiler in the building to improve efficiency, but also CO ₂ is temporarily supplied from a pipe for recirculating the exhaust gas. Even in the case of leakage, it is possible to avoid the CO ₂ being filled into the building in which the boiler is housed.

  According to this embodiment, it is possible to realize an oxyfuel boiler that improves the efficiency by recovering and using the air in the building and the heat of the exhaust gas discharged from the boiler.

  An oxyfuel boiler as a third embodiment in which the present invention is applied to a coal fired boiler will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic diagram showing the configuration of an oxyfuel boiler according to a third embodiment of the present invention, and FIG. 6 is a schematic diagram of a control system for controlling the oxyfuel boiler according to the embodiment of FIG.

  The oxyfuel boiler of the present embodiment shown in FIGS. 5 and 6 is a boiler that can be used by switching from air combustion to oxyfuel combustion.

  Since the basic configuration of the oxyfuel boiler of this embodiment is the same as that of the oxyfuel boiler of the first embodiment shown in FIGS. 1 and 2, the configuration common to both embodiments is omitted and is different. Only described below.

  In the oxyfuel boiler of the present embodiment shown in FIGS. 5 and 6, the circulating gas duct 12 including the fan 103 b branched from the exhaust gas duct 11 and leading the exhaust gas 18 is disposed upstream of the heat exchanger 100 for the circulation. The air duct 10 is connected independently.

Since the circulation gas duct 12 is connected to the circulation air duct 10a on the downstream side of the heat exchanger 100, the exhaust gas 18 mainly composed of CO ₂ supplied by the fan 103b of the circulation gas duct 12 is recycled to the circulation gas duct 12a. The gas duct 12 is supplied to the after-air port portion 101 and the burner portion 102 of the furnace 2 through the circulation air duct 10 a and is recirculated to the furnace 2.

Then, oxygen produced by separating from the air by the oxygen production device 13 is supplied to the circulation air duct 10a, and the exhaust gas 18 mainly composed of CO ₂ flowing down the circulation air duct 10a via the circulation duct 12. And the oxygen are mixed in the circulation air duct 10a to form a support gas 20 and supply it to the burner portion 102 and the after-airport portion 101 of the furnace 2 to burn the fuel by an oxyfuel combustion method. It is used as boiler combustion gas 20.

Furthermore, in this embodiment, the air conditioning damper 104 a installed in the circulation air duct 10 is disposed on the downstream side of the heat exchanger 100. Moreover, CO ₂ sensor 109 for detecting the temperature sensor 110 and the CO ₂ in the air to detect the air temperature in the building 1 are respectively provided in the vicinity of the air inlet 111a of the circulation air duct 10.

  Then, the air was supplied from the circulation air duct 10 downstream of the heat exchanger 100 to the upstream side of the air conditioning damper 104a through the branch pipe 10e through the boiler exhaust gas 18 and the circulation gas duct 12 through the branch pipe 10e. A heat pump 15 that is supplied with air heated by the circulating exhaust gas 17 as a heat medium is installed, and the exhaust heat of the boiler exhaust gas and the exhaust heat of the circulating exhaust gas 17 are reused by the heat pump 15.

  The details of the control system by the control device 115 installed in the oxyfuel boiler of the present embodiment are shown in FIG. 6, but the operation of the oxygen production facility 13 is controlled by the controller 116 provided in the control device 115. In addition to adjusting the amount of oxygen to be produced, the controller 116 of the control device 15 opens the damper 104a provided in the circulation air duct 10 and the damper 104c provided in the branch pipe 10e leading to the heat pump 15. The amount of air supplied is controlled by controlling the opening degree of each.

  Further, the control device 115 controls the operation of the fan 103b provided in the circulation gas duct 12 branched from the exhaust duct 11 and circulates a part of the exhaust gas to the boiler to adjust the suction force thereof, and the circulation air duct. The suction force is adjusted by controlling the operation of the fan 103 a provided in the motor 10.

As shown in FIG. 6, the control system using the control device 115 includes a controller 116 that calculates operation signals output to various operation devices such as the dampers 104 a, 104 b, 104 c, the fans 103 a, 103 b, and the oxygen production device 13. When the boiler operation is switched from the air combustion method to the oxyfuel combustion method, the detected value of the air temperature introduced into the circulation air duct 10 detected by the temperature sensor 110 and the building detected by the CO ₂ sensor 109 Based on the detected value of the CO ₂ concentration of the air in 1, the controller 116 calculates optimum operation signals for the various operation devices, and the controllers 116 provide dampers 104a, 104b, which are various operation devices. Operation signals for controlling the opening degree of the damper 104c, the operation of the oxygen production apparatus 13, and the operation of the fans 103a and 103b are output. It is intended to.

  When operating the oxyfuel boiler of this embodiment in the oxyfuel combustion system, the air temperature in the building 1 rises to 50 ° C to 60 ° C, but the operation of the boiler was switched from the air combustion system to the oxyfuel combustion system. In this case, since the intake of the air supplied to the furnace 2 is not performed, the temperature of the air in the building 1 further rises to about 70 ° C. or higher.

  Therefore, when the boiler is operated by switching to the oxyfuel combustion method, the temperature of the air 14 in the building 1 detected by the temperature sensor 110 is input to the control device 15, and the temperature is set by the controller 116 provided in the control device 15. The value (about 70 ° C.) is compared with the temperature detection value of the temperature sensor 110, and when the air temperature in the building 1 rises above the temperature set value, the circulating air duct 10 is based on the deviation temperature between the two. The output of the fan 103a provided in the circuit is increased, the damper 104a provided in the circulation air duct 10 is fully closed, the damper 104c provided in the branch pipe 104e is fully opened, and the heated air 14 in the building 1 is branched. By supplying and exhausting as a heat source to the heat pump 15 through 104e, the temperature of the air in the building 1 is controlled to be kept below a predetermined temperature set value (about 70 ° C.).

Also in the oxyfuel boiler of this embodiment, about 1% CO ₂ concentration detection value of the CO ₂ concentration in the air detected by the CO ₂ sensor 109 is a set value of CO ₂ concentration by the controller 116 of the controller 115 As in the case of the control by the temperature sensor 110 described above, the operation signal calculated by the controller 116 of the control device 115 is output based on the detected concentration of the CO ₂ sensor 109 and the damper 104a and 104c and the fans 103a and 103b are operated to control the CO ₂ concentration in the air in the building 1 to be less than the CO ₂ concentration set value (about 1%).

  In the oxyfuel boiler of the present embodiment, the damper 104a provided in the circulation air duct 10 is fully opened by the control system by the control device 115 so that the boiler can be operated by an air combustion method at the start of the boiler operation, and the branch pipe. The opening of the damper 104c provided in 10e is operated to be fully closed, and coal as fuel is conveyed to the burner portion 102 and the after-airport portion 101 of the furnace 2 by air as a combustion support gas and burned.

  Next, when the heat recovery in the furnace 2 is stabilized, the oxygen production facility 13 is operated in accordance with the operation command of the control system by the controller 116 of the control device 115, and the oxygen 19 produced by the oxygen production facility 13 is gradually added to the combustion support gas. Into.

  When the operation of the boiler is shifted to the oxyfuel combustion method, the damper 104a provided in the circulation air duct 10 is closed and the fan 103b provided in the circulation gas duct 12 is opened by an operation command from the controller 116 of the control device 115. Then, a part of the exhaust gas 18 is supplied through the circulation gas duct 12 and the circulation air duct 10a and mixed with the oxygen 19 produced by the oxygen production facility 13 to form a combustion support gas for burning the fuel coal.

By transferring this combustion-supporting gas to the burner portion 102 and the after-airport portion 101 of the furnace 2 and burning them, the switching of the boiler from the air combustion method to the oxyfuel combustion method is completed.
At the time of oxyfuel combustion in which the boiler is burned by the oxyfuel combustion method, air 14 is not included in the combustion support gas, so that the ratio of CO _{2 in} the exhaust gas 16 is increased. Therefore, NO x removal apparatus 4, the whole or a part of the dedusting apparatus 5 and the exhaust gas treated exhaust gas 18 in the desulfurization device 6 was supplied to the CO ₂ recovery facility 9, the separation of CO ₂ of the exhaust gas 18 in the CO ₂ recovery facility 9 And CO ₂ is recovered.

The circulation gas duct 12 is connected to the circulation air duct 10 on the downstream side of the heat exchanger 100.
In addition, the circulating exhaust gas 17 flowing down the circulating gas duct 12 is branched into one that is directly led to the after-airport portion 101 and the burner portion 102 of the furnace 2 and one that is led to the fuel supply device 3.

  The circulating exhaust gas 17 supplied to the after-airport unit 101 and the burner unit 102 of the furnace 2 is mixed with the oxygen 19 supplied from the oxygen production device 13 before being led to the after-airport unit 101 and the burner unit 102 to burn the fuel. The supporting gas is formed.

  On the other hand, the air sucked by the fan 103a from the air intake port 111 of the circulation air duct 10 is guided to the heat pump 15 as the exhaust heat utilization device through the branch pipe 10e, and the exhaust gas 18 discharged from the furnace 2 by the heat pump 15. Use the exhaust heat of the water effectively.

Based on the detected value of the air temperature introduced into the circulating air duct 10 detected by the temperature sensor 110 and the detected value of the CO ₂ concentration in the building 1 detected by the CO ₂ sensor 109, the controller 116 Optimum operation signals for various operation devices are calculated and output, and the controller 116 adjusts the opening of the dampers 104a and 104c, which are the various operation devices, the operation of the oxygen production apparatus 13, and the operation of the fans 103a and 103b. It functions to output each operation signal that controls.

  That is, in the control system of the control device 115, the detected value of the air temperature in the building 1 detected by the temperature sensor 110 provided in the vicinity of the air intake port 111b of the exhaust air duct 107 is the air temperature during normal operation. When the temperature rises above 50 ° C. to 60 ° C. and rises to a high temperature of, for example, 70 ° C. to 80 ° C., the controller 116 of the control device 115 calculates and outputs the temperature based on the detected temperature of the temperature sensor 110. A temperature setting value (about 70 ° C.) is compared with the temperature detection value of the temperature sensor 110 by an operation signal, and when the air temperature in the building 1 rises above the temperature setting value, the temperature is set based on the deviation temperature between the two. The suction force of the fan 103a provided in the circulation air duct 10 is increased, the damper 104a is fully closed, the damper 104c provided in the branch pipe 10e is opened forward, and the heated air 14 The heat pump 15 is introduced as a heat source, to recover the energy of the air 14 the temperature was raised.

By recovering the energy of the heated air 14 by the heat pump 15, in this embodiment, the efficiency of the entire boiler can be improved by about 0.2 to 0.6%.
In addition, although description is abbreviate | omitted in the present Example, it is that the thermal power generation system provided with the steam turbine plant and heat pump shown in FIG. 7 is installed in the boiler of a present Example, and the oxyfuel boiler of 1st Example. It is the same.

In the present embodiment described above, not only can an oxyfuel boiler that efficiently recovers the heat of exhaust gas discharged from the air and boiler in the building to improve efficiency, but also CO ₂ is temporarily supplied from a pipe for recirculating the exhaust gas. Even in the case of leakage, it is possible to avoid the CO ₂ being filled into the building in which the boiler is housed.

  In addition, although description is abbreviate | omitted in the present Example, it is that the thermal power generation system provided with the steam turbine plant and heat pump shown in FIG. 7 is installed in the boiler of a present Example, and the oxyfuel boiler of 1st Example. It is the same.

  According to this embodiment, it is possible to realize an oxyfuel boiler that improves the efficiency by recovering and using the air in the building and the heat of the exhaust gas discharged from the boiler.

  The present invention can be applied to an oxyfuel boiler, and particularly applicable to an oxyfuel boiler capable of switching from air combustion to oxyfuel combustion.

1: Building, 2: furnace 3: fuel supply device, 4: denitration apparatus 5: dust collector, 6: desulfurizer, 7: chimney, 8: Fuel, 9: CO ₂ recovery facility, 10: circulating air Duct, 10e: Branch pipe, 11: Exhaust gas duct, 12: Circulating gas duct, 13: Oxygen production facility, 14: Air, 15: Heat pump, 17: Circulating exhaust gas, 18: Exhaust gas, 19: Oxygen, 21: Heat medium, 100 : heat exchanger, 101: OFA, 102: burner, 103, 103a, 103b: fan, 104a, 104b, 104c: damper, 106: turbine, 107: exhaust air duct, 108: closing plate, 109: CO ₂ sensor , 110: temperature sensor, 111: air inlet, 112: superheater, 113: reheater, 114: economizer, 115: controller, 116: controller.

Claims (9)

A boiler that generates steam using combustion gas generated by burning fuel as a heat source, and a furnace that constitutes the boiler includes air combustion that burns fuel and air, and an exhaust gas mainly composed of carbon dioxide discharged from the furnace. In an oxyfuel boiler capable of both oxyfuel combustion in which fuel is combusted with a support gas formed by mixing oxygen,
In the building that houses the boiler furnace, an air duct having an air intake for the air supplied to the boiler is disposed.
Provided on the downstream side of this air duct is a heat exchanger that raises the temperature of the air supplied through the air duct as an exhaust gas discharged from the furnace and supplies it to the boiler,
Arranged so that a circulating gas duct for guiding a part of the exhaust gas discharged from the furnace is connected to the air duct on the upstream side of the heat exchanger,
Installed an oxygen production device that produces oxygen separated from the air, and supplied oxygen to the furnace with oxygen produced by the oxygen production device and the exhaust gas introduced by the circulating gas duct when the boiler was burned with oxygen Configured to burn the fuel,
In addition to installing an exhaust air duct with a turbine inside in the upper part of the building, installing an opening and closing member at the air intake of the exhaust air duct,
Install a temperature detector to detect the temperature of air in the building,
A control device that performs an operation of switching the boiler from air combustion to oxyfuel combustion is installed, and air in the building is exhausted through the exhaust air duct based on the temperature of the air detected by the temperature detector by the control device. An oxyfuel boiler characterized by adjusting a flow rate and adjusting a flow rate of air supplied to a heat exchanger by flowing down the air duct and a flow rate of exhaust gas supplied through the circulation gas duct. A boiler that generates steam using combustion gas generated by burning fuel as a heat source, and a furnace that constitutes the boiler includes air combustion that burns fuel and air, and an exhaust gas mainly composed of carbon dioxide discharged from the furnace. In an oxyfuel boiler capable of both oxyfuel combustion in which fuel is combusted with a support gas formed by mixing oxygen,
In the building that houses the boiler furnace, an air duct having an air intake for the air supplied to the boiler is disposed.
Provided on the downstream side of this air duct is a heat exchanger that raises the temperature of the air supplied through the air duct as an exhaust gas discharged from the furnace and supplies it to the boiler,
Arranged so that a circulating gas duct for guiding a part of the exhaust gas discharged from the furnace is connected to the air duct on the downstream side of the heat exchanger,
Installed an oxygen production device that produces oxygen separated from the air, and supplied oxygen to the furnace with oxygen produced by the oxygen production device and the exhaust gas introduced by the circulating gas duct when the boiler was burned with oxygen Configured to burn the fuel,
Installed a heat pump that uses air guided through the branch pipe branched from the air duct on the downstream side of the heat exchanger as a heat source,
Install a temperature detector to detect the temperature of air in the building,
A control device for performing an operation of switching the boiler from air combustion to oxyfuel combustion is installed, and the flow rate of air supplied to the heat pump through the branch pipe is adjusted based on the temperature of the air detected by the temperature detector by the control device, An oxyfuel boiler characterized by adjusting a flow rate of air supplied to a heat exchanger by flowing down the air duct and a flow rate of exhaust gas supplied through the circulation gas duct. A boiler that generates steam using combustion gas generated by burning fuel as a heat source, and a furnace that constitutes the boiler includes air combustion that burns fuel and air, and an exhaust gas mainly composed of carbon dioxide discharged from the furnace. In an oxyfuel boiler capable of both oxyfuel combustion in which fuel is combusted with a support gas formed by mixing oxygen,
In the building that houses the boiler furnace, an air duct having an air intake for the air supplied to the boiler is disposed.
Provided on the downstream side of this air duct is a heat exchanger that raises the temperature of the air supplied through the air duct as an exhaust gas discharged from the furnace and supplies it to the boiler,
A circulation gas duct for guiding a part of the exhaust gas discharged from the furnace to the heat exchanger is connected, and the circulation gas duct is arranged to be connected to an air duct on the downstream side of the heat exchanger,
Installed an oxygen production device that produces oxygen separated from the air, and supplied oxygen to the furnace with oxygen produced by the oxygen production device and the exhaust gas introduced by the circulating gas duct when the boiler was burned with oxygen Configured to burn the fuel,
Installed a heat pump that uses air guided through the branch pipe branched from the air duct on the downstream side of the heat exchanger as a heat source,
Install a temperature detector to detect the temperature of air in the building,
A control device for performing an operation of switching the boiler from air combustion to oxyfuel combustion is installed, and the flow rate of air supplied to the heat pump through the branch pipe is adjusted based on the temperature of the air detected by the temperature detector by the control device, An oxyfuel boiler characterized by adjusting a flow rate of air supplied to a heat exchanger by flowing down the air duct and a flow rate of exhaust gas supplied through the circulation gas duct.   The oxyfuel boiler according to claim 1, wherein a carbon dioxide detector that detects a concentration of carbon dioxide in the air is installed at an upper part of the building, and the carbon dioxide in the air detected by the carbon dioxide detector by the control device. The flow rate of the air exhausted through the exhaust air duct is adjusted based on the concentration of the air, and the flow rate of the air supplied to the heat exchanger by flowing down the air duct and the exhaust gas supplied through the circulation gas duct An oxyfuel boiler characterized by being configured to adjust the flow rate of each.   The oxyfuel boiler according to claim 2 or claim 3, wherein a carbon dioxide detector for detecting a concentration of carbon dioxide in the air is installed at the upper part of the building, and the carbon dioxide detector is detected by the control device. The flow rate of air supplied to the heat pump through the branch pipe is adjusted based on the concentration of carbon dioxide, and the flow rate of air supplied to the heat exchanger by flowing down the air duct and the flow rate of exhaust gas supplied through the circulation gas duct are adjusted. An oxyfuel boiler configured to adjust each of the boilers.   2. The oxyfuel boiler according to claim 1, wherein the flow rate of the air exhausted through the air duct for exhausting the air in the building operated by the control device is adjusted by an opening / closing member installed at an air intake port of the exhaust air duct The flow rate of the air that flows down the air duct and is supplied to the heat exchanger is adjusted by opening and closing the first damper installed in the air duct and operating the first suction fan. An oxygen combustion boiler characterized in that the flow rate of the exhaust gas supplied through the circulation gas duct is controlled by controlling the opening and closing of the second damper installed in the circulation gas duct.   The oxyfuel boiler according to claim 2 or 3, wherein the flow rate of air supplied to the heat pump through the branch pipe operated by the control device is adjusted to control the opening and closing of the first damper installed in the branch pipe. The flow rate of the air supplied to the heat exchanger after flowing down the air duct is adjusted by controlling the opening / closing of the second damper installed in the air duct and the operation of the first suction fan. The oxygen combustion boiler is characterized in that the flow rate of the exhaust gas supplied through the circulation gas duct is adjusted by controlling the operation of the second suction fan installed in the circulation gas duct. The oxyfuel boiler according to any one of claims 1 to 3, wherein a denitration device, a dedusting device, and a desulfurization device are used as an exhaust gas treatment device for exhaust gas discharged from the furnace downstream of the furnace of the oxyfuel boiler. There has been equipped sequentially, the exhaust gas denitration apparatus exiting from the furnace, dust removal, is guided in the order of the desulfurization apparatus is an exhaust gas treatment, the CO ₂ contained in the exhaust gas, which is the exhaust gas treatment downstream of the desulfurization apparatus An oxyfuel boiler characterized in that a CO ₂ recovery device for separation and recovery is installed.   The oxyfuel boiler according to any one of claims 1 to 3, wherein a steam turbine driven by steam generated from a superheater and a reheater installed in a furnace of the boiler is installed. A heat pump that heats the condensate is installed between a condenser installed in the steam turbine as a waste heat utilization device and a feed water pump that supplies the condensate to the economizer installed in the furnace. An oxyfuel boiler characterized in that the air flowing in the duct is supplied as a heating medium of the heat pump.

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