JPH08159413A - Desulfurizer supply method and apparatus for fluidized boiler - Google Patents

Abstract

PURPOSE: To deal with a trouble immediately when there is produced the condition temporarily requiring a large quantity of a desulfurizer on a process side by injecting and dispersing a fuel together with fuel dispersed air, and mixing the desulfurizer in the fuel dispersed air to supply it into a boiler body together with the fuel dispersed air. CONSTITUTION: A mixture for mixing aqueous calcium being a desulfurizer is connected with an air pipe 19 for fuel dispersed air, and the aqueous calcium increased by a predetermined amount in its pressure from a calcium tank 21 through a calcium pump 23 is mixed with the fuel dispersed air. The mixed aqueous calcium is carried in the air pipe 19 and is supplied into the fluidized bed 6 together with the fuel dispersed air from the nozzle. Hereby, in-bed desulfurization is achieved. Aqueous calcium is mixed with the fuel dispersed air that disperses a fuel in such a manner. Since the aqueous calcium is hereby injected with the fuel, there is improve a contact efficiency of the aqueous calcium and SOx.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply method and apparatus for a fluidized bed boiler for supplying a desulfurizing agent into a boiler body.

[0002]

2. Description of the Related Art A fluidized bed boiler is known as a boiler for efficiently burning solid fuel.
In recent years, a pressurized fluidized bed boiler is being researched and developed, which can burn fuel with high combustion efficiency and can achieve compactness, high desulfurization rate, and improvement of plant thermal efficiency.

A pressurized fluidized bed boiler, as shown in FIG.
High-pressure air is supplied to the pressure vessel 2 in which the boiler body 1 is housed, and combustion air in the pressure vessel 2 is supplied to the boiler body 1
The fuel (e.g., coal) from the fuel tank 30 and the fuel nozzle 31 is fluidized together with the bed material and burned under high temperature and high pressure, and a part of the combustion heat in the fluidized bed 6 is transferred to the heat transfer tube. Heat is collected via 9 and steam generated thereby is supplied to a steam turbine or the like, and combustion exhaust gas from the boiler body 1 is supplied to a gas turbine or the like.

[0004]

In the fluidized bed boiler described above, SOx is generated when fuel (coal) is burned. Therefore, limestone, which is a desulfurizing agent, is charged into the fluidized bed boiler to desulfurize the layer. It is carried out. As a desulfurizing agent supply means,
It may be injected into the boiler body together with coal, or may be injected using a system separate from the fuel (exclusive nozzle or pump). The former method utilizes crushed coal as water slurry and blows it into the main body. This slurry (CW is made by mixing crushed coal with limestone).
Desulfurization is performed by supplying M) into the boiler body.
However, conditions that require a large amount of desulfurizing agent on the process side, such as when the load changes (transitionally increases SOx generation)
If a spill occurs, even if the amount of limestone supplied to the slurry manufacturing equipment is increased, the amount of desulfurizing agent supplied to the boiler body (input amount)
There is a time delay with respect to. If there is a time delay with respect to the increase / decrease in the supply amount of the desulfurizing agent, the desulfurization rate may deteriorate. In the latter case, since limestone is made into a slurry and supplied to the boiler body by a nozzle of another system,
It is possible to cope with a transient increase in SOx. However, SOx is a sulfur content of coal, and if the coal and the desulfurization agent (limestone) are separately ejected, the contact efficiency between the desulfurization agent and SOx is deteriorated and the desulfurization effect is small.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to provide a fuel supply method for a fluidized bed boiler and a device therefor capable of achieving high desulfurization efficiency.

[0006]

In order to achieve the above object, a fuel supply method for a fluidized bed boiler of the present invention is a fluidized bed boiler in which a fuel is combusted while fluidizing the fuel in a boiler body. It is jetted together with dispersed air to be dispersed, and the desulfurizing agent is mixed into the fuel dispersed air and supplied into the boiler main body together with the fuel dispersed air.

The fuel supply system for a fluidized bed boiler of the present invention is
In a fluidized bed boiler in which a bed material is fluidized by combustion air in a boiler body to form a fluidized bed, and fuel is jetted from the fuel nozzle to the fluidized bed, fuel dispersed air is jetted and jetted to the fuel nozzle. A fuel dispersion air nozzle for diffusing the fuel is provided, and a mixer for mixing a desulfurization agent with the fuel dispersion air and supplying the desulfurization agent together with the fuel dispersion air into the boiler main body is provided.

[0008]

The fuel is dispersed and burned in the fluidized bed by the fuel-dispersed air. Since the desulfurizing agent is mixed with the fuel-dispersed air, the desulfurizing agent is supplied into the fluidized bed, so that the in-layer desulfurization is performed. Since the desulfurizing agent is mixed with the fuel-dispersed air for dispersing the fuel in this way, the desulfurizing agent is ejected together with the fuel, so that the SOx and the desulfurizing agent are in sufficient contact. Also,
Since the desulfurization agent is mixed with the fuel-dispersed air and supplied to the boiler main body, there is no time delay with respect to the change in the supply amount of the desulfurization agent. It is possible to take immediate action, and it is possible to suppress a transient increase in SOx. Therefore, the desulfurization efficiency is increased.

[0009]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In this embodiment, a case of a pressurized fluidized bed boiler will be described as the fluidized bed boiler.

In FIG. 1, reference numeral 1 denotes a boiler body housed in a pressure vessel 2, and a plurality of fuel nozzles 3 for ejecting fuel (coal water slurry (CWM)) are provided below the boiler body 1. For the sake of clarity, only one is provided in the illustrated example).

An air supply pipe 4 is connected to the pressure vessel 2,
High-pressure air is supplied from the air supply pipe 4 to the pressure container 2 to increase the pressure in the container 2 and then is injected into the boiler main body 1 through the air conduit 5, and the ash is generated by this air. The bed material such as fluidized to form the fluidized bed 6,
The fuel is configured to burn under high temperature and high pressure (for example, about 15 to 16 kg / cm ² ).

An exhaust gas pipe 8 having a cyclone 7 in the pressure vessel 2 is connected to the upper portion of the boiler body 1, and the exhaust gas flowing into the exhaust gas pipe 8 is guided to the gas turbine or the like via the cyclone 7. A heat transfer tube 9 that collects a part of combustion heat in the fluidized bed 6 to generate steam is provided in the boiler body 1, and the steam from the heat transfer tube 9 is guided to a steam turbine or the like.

A fuel pipe 10 is connected to the fuel nozzle 3,
A fuel pump 11 and a three-way valve 12 are provided in the fuel pipe 10. The fuel pipe 10 is connected to a fuel tank 13, and the fuel tank 13 is connected to a fuel supply pipe 14 to which a fuel such as coal water slurry (CWM) is supplied.
The CWM manufactured by the WM manufacturing device is the fuel tank 13
It is designed to be supplied and stored in.

The three-way valve 12 is provided in the fuel tank 13.
The three-way valve 12 connects the CWM from the fuel pump 11 to the fuel tank through the circulation pipe 15 so that the CWM does not clog the fuel pipe 10 at the time of start-up or boiler operation interruption. Return to 13 and C during boiler operation
The opening / closing is adjusted so that the WM is supplied to the fuel nozzle 3.

As shown in FIGS. 1 and 2, the fuel nozzle 3 is formed in a vertical cylindrical shape with its upper part closed.
The jet port 16 is opened at the upper side portion thereof, and the jet port 16
Fuel is jetted from the inside into the boiler body 1 (fluidized bed 6). Behind the ejection port 16 inside the nozzle 3, a fuel-dispersed air nozzle 17 for ejecting the fuel-dispersed air to disperse the fuel from the ejection port 16 is provided. An air pipe 19 which is connected to the pressure vessel 2 and has an air pump 18 is connected to the fuel dispersion air nozzle 17, and a part of the air in the pressure vessel 2 is connected to the air pump 18.
The pressure is increased by and is ejected from the fuel dispersion air nozzle 17 as fuel dispersion air. A mixer 20 for mixing a desulfurizing agent (water-soluble calcium) is provided outside the pressure vessel 2 on the downstream side of the air pump 18 in the air pipe 19. Water-soluble calcium is one in which calcium exists in an ionic state, and calcium ions react with SOx to effect desulfurization. A calcium pipe 22 connected to a calcium tank 21 that stores water-soluble calcium is connected to the mixer 20. The calcium pipe 22 is provided with a calcium pump 23 for increasing the pressure of water-soluble calcium to a predetermined pressure and a flow rate control valve 24. The flow rate control valve 24 controls the amount of water-soluble calcium mixed with the fuel-dispersed air. It has become so. The supply amount of the water-soluble calcium is adjusted according to the amount of SOx in the combustion exhaust gas from the boiler body 1, for example.

Next, the operation of this embodiment will be described.

When high-pressure combustion air is supplied from the air supply pipe 4 into the pressure vessel 2, the pressure inside the vessel 2 becomes high (for example, about 10.5).
kg / cm ² ), and due to the pressure difference between the inside of the boiler main body 1 and the inside of the container 2, the air inside the container 2 flows into the boiler main body 1 through the air conduit 5. The inflowing air fluidizes the bed material under high temperature and high pressure (for example, at about 860 ° C. and 10 kg / cm ² ) to form a fluidized bed 6, and the fluidized bed 6 is provided with fuel ( CWM) is ejected and coal burns.

Since the fuel nozzle 3 is provided with the fuel dispersion air nozzle 17, the CWM ejected from the fuel nozzle 3 is dispersed in the fluidized bed 6 by the air from the fuel dispersion air nozzle 17. When only the CWM is ejected, the fuel does not spread and the dispersibility of the fuel in the fluidized bed 6 deteriorates and heat spots are created. However, by dispersing the CWM with the fuel dispersion air at a speed, Dispersibility is improved and no heat spot occurs.

A mixer 20 for mixing water-soluble calcium, which is a desulfurizing agent, is connected to the air pipe 19 of the fuel-dispersed air, and the water-soluble calcium is pressurized from a calcium tank 21 to a predetermined pressure via a calcium pump 23. Are mixed with fuel dispersed air. The mixed water-soluble calcium is conveyed in the air pipe 19 and supplied from the nozzle 17 into the fluidized bed 6 together with the fuel-dispersed air. As a result, in-layer desulfurization is performed. Thus, by mixing the water-soluble calcium with the fuel-dispersed air for dispersing the fuel, the water-soluble calcium is ejected together with the fuel, so that the contact efficiency between the water-soluble calcium and SOx is high. Also, since water-soluble calcium is supplied with air, although it is for fuel dispersion,
Since the sulfur content in the fuel becomes SOx, the water-soluble calcium and SOx sufficiently come into contact with each other. Further, since the water-soluble calcium is mixed with the fuel-dispersed air and supplied to the boiler main body 1, there is no time delay with respect to the increase / decrease in the supply amount (input amount) of the desulfurizing agent (water-soluble calcium). If a condition that requires a large amount of time temporarily occurs, it can be immediately dealt with, and a transient increase in SOx can be suppressed. Therefore, the desulfurizing agent is ejected together with the fuel, and the supply amount thereof can be arbitrarily adjusted, so that the desulfurizing efficiency is increased.

When the desulfurizing agent is a solid such as limestone, it is supplied in the form of a slurry, so a special pump or the like dedicated to the slurry is required. However, by using water-soluble calcium as the desulfurizing agent, the desulfurizing agent can be removed. Since it can be sent by an ordinary pump 23 and water-soluble calcium is mixed outside the pressure vessel 2, the supply device can be a simple device. Therefore, high desulfurization efficiency can be achieved with a simple system.

Furthermore, the water-soluble calcium has an operating molar ratio of about 1 / 2.5 of that of limestone conventionally used as a desulfurizing agent.
Since the supply amount is small, the ash emission amount is small.

[0023]

In summary, according to the present invention, the desulfurizing agent is ejected together with the fuel, and the supply amount thereof can be adjusted arbitrarily, so that the desulfurizing efficiency can be enhanced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an outline of a main part of the present invention.

FIG. 3 is a configuration diagram showing an example of a pressurized fluidized bed boiler.

[Explanation of symbols]

 1 Boiler body 3 Fuel nozzle 17 Fuel dispersion air nozzle 20 Mixer

Claims (2)

[Claims] 1. A fluidized-bed boiler that combusts fuel while fluidizing it in a boiler body, jets and disperses the fuel together with fuel-dispersed air, and mixes a desulfurizing agent in the fuel-dispersed air to disperse the fuel. A method for supplying a desulfurizing agent to a fluidized bed boiler, which is characterized in that the gas is supplied into the boiler main body together with it. 2. A fluidized bed boiler in which a bed material is fluidized by combustion air in a boiler body to form a fluidized bed, and fuel is jetted from the fuel nozzle to the fluidized bed. And a mixer for supplying a desulfurizing agent into the boiler main body together with the fuel dispersing air by mixing the fuel dispersing air with a desulfurizing agent. Desulfurizing agent supply device for fluidized bed boiler.