JP2009174745A - Draft system in steam power generation facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat efficiency in draft by changing a facility location in a draft system, and to improve efficiency in removing a sulfur oxide, a nitrogen oxide (SOx, NOx), ash particles and the like in an exhaust gas. <P>SOLUTION: This ventilation system composed of an air system A and an exhaust gas system E comprises a forced draft fan 3 taking outside air (a) and forcibly feeding it to a furnace 1 as combustion air, an air preheater 5 exchanging heat with the residual heat of the exhaust gas system E from the furnace 1 to heat air (a) taken by the forced draft fan 3 up to a temperature of about 200°C, and an electric dust collector 8 collecting the ash particles in the exhaust gas (e) exchanging heat by the air preheater 5 before being distributed to a chimney 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steam power generation facility, and more particularly to a ventilation system in a steam power generation facility that supplies air necessary for combustion in a furnace after heating and heating with air generated by combustion in the furnace.

Steam power generation equipment is equipment that burns fuel such as heavy oil or coal in a boiler, generates high-pressure and high-temperature steam with its heat, and rotates a steam turbine and a generator to generate electric power. Steam power generation equipment is composed of various auxiliary equipment in addition to main equipment such as boilers, turbines, and generators. When these facilities are classified by function, they are composed of fuel receiving / storage facilities, boiler facilities, steam turbine facilities, condensate / water supply system facilities, generators and electrical facilities, and measurement control devices and facilities. Here, the fuel receiving / storage facility is a trading metering device, a fuel tank such as heavy crude oil, LNG, or LPG, a fuel oil pump, an LNG pump, a vaporizer, or the like. The boiler equipment includes a boiler body, heavy crude oil pump, burner, ventilator, air preheater, dust collector, ash treatment device, and chimney. The steam turbine equipment includes a turbine body, a lubricating oil device, a speed governor, and the like. Condensate and water supply system facilities include condensers, circulating water pumps, condensate pumps, feed water heaters,
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, Water supply processing equipment. Generators and electrical equipment are generators, exciters, transformers, switchgears, cables and the like. The measurement control device includes various measurement devices, a monitoring device, a plant general control device, an automatic burner device, and a computer control device. The facilities include on-site cooling water equipment, on-site air equipment, wastewater treatment equipment, and safety and disaster prevention equipment.

  Combustion air is supplied in order to send fuel such as heavy oil or coal into the furnace for combustion. The high-pressure and high-temperature superheated steam generated in the boiler by the combustion of this furnace is sent to the turbine, and the heat energy of the steam is converted into mechanical energy by this turbine, and the generator directly connected to the turbine is operated and converted into electric energy. The exhaust gas exiting the boiler removes sulfur / nitrogen oxides (SOx, NOx, etc.), ash particles, etc., and then sends it to the chimney for release to the atmosphere.

In view of this, there has been proposed a boiler facility capable of reducing NOx, improving reheat steam temperature controllability, reducing furnace wall corrosion, and reducing clinker adhesion. For example, as shown in Japanese Patent Application Laid-Open Publication No. 2003-151780, "Exhaust gas recirculation device for boiler equipment", a recirculation gas system that recirculates a part of the exhaust gas discharged from the boiler body to the furnace bottom of the boiler body; An apparatus has been proposed in which an air system that supplies a part of combustion air is connected so as to be switchable.
JP 2002-181307 A

  However, the “exhaust gas recirculation device for boiler equipment” of Patent Document 1 can perform optimal combustion adjustment according to the coal type, reduce NOx, improve reheat steam temperature controllability, reduce furnace wall corrosion, and It was intended only to reduce clinker adhesion, and did not attempt to control the entire ventilation system safely and accurately, and to further improve thermal efficiency.

  The present invention has been developed to solve such problems. That is, the object of the present invention is to improve the thermal efficiency of ventilation by changing the equipment layout in the ventilation system, and to improve the removal efficiency of sulfur / nitrogen oxides (SOx, NOx), ash particles, etc. in the exhaust gas. It is to provide a ventilation system in a steam power generation facility capable of generating electricity.

  According to the ventilation system of the present invention, in order to supply air (a) necessary for combustion in the furnace (1) after heating and heating with the exhaust gas (e), the air system (A) and the exhaust system (E) A ventilating system in a steam power generation facility comprising an outside air (a) and a forced air blower (3) for pushing into the furnace (1) as combustion air, and the forced air ventilator In order to heat the air (a) taken in (3) to about 200 ° C., an air preheater (5) for exchanging heat with the residual heat of the exhaust gas system (E) from the furnace (1), and the air preheating Ventilation in a steam power generation facility comprising: an electric dust collector (8) that collects ash particles in the exhaust gas (e) heat-exchanged in the vessel (5) before blowing to the chimney (2) A system is provided.

While adjusting the amount of gas recirculation between the downstream of the exhaust gas system (E) of the furnace (1) and between the air preheater (5) and the air system (A) of the furnace (1), the furnace ( It is preferable to arrange a gas recirculation ventilator (6) that varies the heat absorption rate of 1).
Nitrogen oxide (NOx) in the exhaust gas (e) is downstream between the gas recirculation ventilator (6) and between the air preheater (5) and the air system (A) of the furnace (1). It is preferable to arrange a gas recirculation booster fan (7) that reduces and heats the air (a) from the air preheater (5).

Air (a) taken from the forced air blower (3) is supplied between the forced air blower (3) and the air system (A) of the air preheater (5) as auxiliary steam or turbine of the boiler. It is preferable to arrange a steam type air heater (4) that heats from room temperature to about 100 ° C. by heat exchange of steam from.
A denitration reactor (10) for removing nitrogen oxides (NOx) in the exhaust gas (e) may be disposed between the furnace (1) and the exhaust gas system (E) of the air preheater (5). preferable.
It is preferable to arrange a denitration ventilator (DNF) (11) downstream of the exhaust gas system (E) of the air preheater (5).

In the invention with the above configuration, air (a) necessary for combustion in the furnace (1) is supplied to fuel such as heavy oil to achieve complete combustion, and combustion product gas (exhaust gas (e)) is transferred to the furnace (1). The heat efficiency can be increased by allowing the heat to flow while being in contact with the hot surface and effectively releasing the residual heat from the chimney (2) to the atmosphere.
Moreover, nitrogen oxide (NOx) can be reduced by adjusting the combustion temperature in the furnace (1) by the gas recirculation ventilator (6).

  The ventilation system in the steam power generation facility of the present invention supplies the air necessary for combustion to the fuel for complete combustion, flows the combustion product gas (exhaust gas) through the flue while contacting the boiler heat transfer surface, and holds it It is a series of air and gas flow systems that use heat as effectively as possible to release it from the chimney to the atmosphere.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system diagram showing a ventilation system in the steam power generation facility of the first embodiment.
In the ventilation system in the steam power generation facility of Example 1, the air a necessary for combustion in the furnace 1 is heated and heated by the exhaust gas e and then supplied, and then the exhaust gas e is discharged from the chimney 2. It is a system composed of an air system A and an exhaust gas system E.

  Major facilities in the air system A include a forced air blower (FDF) 3, a steam air heater (SAH) 4, an air preheater (AH) 5, and the like. The main equipment in the exhaust gas system E includes a gas recirculation ventilator (GRF) 6, a gas recirculation booster fan (GRBF) 7, an air preheater 5, an electric dust collector 8, and the like.

  The forced air ventilator (FDF) 3 is an air ventilator for taking in external air a and forcing it into the furnace 1 as combustion air. The forced draft fan 3 needs to adjust the air amount necessary for combustion in a wide flow rate range and needs to be operated in a stable state. As its structure, centrifugal turbofans are often used. In addition, the axial flow type is characterized in that the efficiency in the low load region is superior to the centrifugal type. The axial flow type forced air blower 3 has, for example, 16 blades connected to a rotating shaft, rotates at about 2000 rotations per minute, and moves a moving blade that pushes air in the axial direction, and an air flow sent by the moving blade. It consists of a stationary blade that works to correct the disturbance.

  Equipment such as this push-in ventilator 3 and air preheater 5 to be described later is provided with a damper device 9 for the purpose of partitioning. These damper devices 9 are configured to block wind (smoke) by combining several dampers. For example, during normal operation, the wind pressure loss is reduced by 90 °. The damper is opened and closed by a driving device comprising a motor, a speed reducer and a link mechanism. The damper device 9 is partly disconnected from the wind flue system even during operation of the boiler, and equipment can be inspected.

  The steam type air heater (SAH) 4 is a device that heats the air a taken in from the forced air blower 3 from room temperature to about 100 ° C. by heat exchange of auxiliary steam of the boiler or steam from the turbine. The steam type air heater 4 is disposed between the forced air blower 3 and the air system A of the air preheater 5. The structure of the steam type air preheater 5 is configured such that, for example, steam passes through a tube and air passes outside. A tube with fins is used to increase the heat transfer area. The amount of steam is adjusted by a temperature control valve so that the temperature of the element of the steam air preheater 5 is maintained at or above the gas dew point. Average temperature is used as an index of element temperature. The steam type air heater 4 is a pump that exchanges heat with a drain tank steam type air preheater and stores the drained hot water, and sends the hot water stored in the drain tank. It consists of a drain pump that recovers heat, and the drain tank water level is adjusted by the drain tank water level control valve so as to keep the drain tank water level constant.

  The air preheater (AH) 5 is a device for exchanging heat with the residual heat of the exhaust gas system E from the furnace 1 in order to heat the air a taken in by the forced air blower 3 to about 200 ° C. The air preheater 5 is installed between the steam air heater 4 and the furnace 1.

  The air preheater (AH) 5 reduces the heat loss of the exhaust gas e, increases the boiler efficiency, and increases the combustion air temperature, thereby increasing the combustion efficiency and reducing the excess air amount. In addition, the ignition conditions are improved and the adaptability to the fuel used is increased. The type of the air preheater 5 is roughly classified into a heat transfer type and a regenerative type depending on the heat transfer process.

  For example, the regenerative air preheater (AH) 5 is composed of a corrugated steel plate having a thickness of about 0.6 to 1.2 mm, which is housed in a cylindrical container as a heat transfer body, and around its central axis. By rotating at 2-3 rpm, the combustion air can be efficiently preheated by accumulating the temperature of the exhaust gas e in the flue and radiating heat on the air side. The heat transfer body is divided into two or three along the gas flow, which are called the high temperature part, the medium temperature part, and the low temperature part, respectively, and a mild steel plate, a corrosion-resistant alloy steel plate, and an enamel coating plate are used as necessary. Consideration is given to low-temperature corrosion in the low-temperature part. The sector side plate separates the air side and the gas side. In addition, a seal plate is attached to the rotor in order to reduce leakage air to the gas side from the gap between the rotor and the housing or between the rotor and the sector plate.

  The furnace 1 is supplied with a mixture of fuel (not shown) and air a having a high temperature in the air system A. High-pressure and high-temperature superheated steam generated in the boiler by combustion in the furnace 1 is sent to a turbine, and the heat energy of the steam is converted into mechanical energy by the turbine. A generator directly connected to the turbine is operated and converted into electric energy.

  On the other hand, in the furnace 1, the exhaust gas e having a high temperature of about 1500 ° C. is circulated through the exhaust gas system E. At this time, the remaining heat is effectively utilized, and sulfur / nitrogen oxides (SOx, NOx, etc.) and ash particles in the exhaust gas e are removed and then sent to the chimney 2.

  An air preheater 5 is disposed downstream of the exhaust gas system E of the furnace 1. In the air preheater 5, heat is exchanged by the residual heat of the exhaust gas e to raise the temperature of the air a.

  An electric dust collector 8 is disposed downstream of the air preheater 5. The electric dust collector 8 collects the ash particles in the exhaust gas e heat-exchanged by the air preheater 5 before blowing them to the chimney 2.

Further, a gas recirculation ventilator (GRF) 6 and a gas recirculation booster fan (GRBF) 7 are arranged downstream of the exhaust gas system E of the furnace 1.
The gas recirculation ventilator (GRF) 6 adjusts the amount of gas recirculation between the downstream of the exhaust gas system E of the furnace 1 and the air system A of the air preheater 5 and the furnace 1, and heats the furnace 1. A ventilator that changes the absorption rate. This gas recirculation ventilator 6 is a ventilator that sucks the exhaust gas e at the boiler outlet and supplies it again from the bottom of the furnace 1, adjusts the amount of gas recirculation, and changes the heat absorption rate of the furnace 1. It has the function of adjusting the reheater outlet steam temperature by changing the amount and temperature of gas passing through the superheater and reheater. The exhaust gas temperature is as high as 350 to 450 ° C., and a centrifugal turbofan is used.

  The gas recirculation booster fan 7 is a ventilator disposed downstream of the gas recirculation ventilator 6 and between the air system A of the air preheater 5 and the furnace 1. The gas recirculation booster fan 7 reduces nitrogen oxide (NOx) and heats it.

  In the present invention, air a necessary for combustion in the furnace 1 is supplied to fuel such as heavy oil to achieve complete combustion, and the combustion generated gas is circulated while contacting the heat transfer surface of the furnace 1 to effectively use the remaining heat. Then, the thermal efficiency can be enhanced by discharging the chimney 2 to the atmosphere.

FIG. 2 is a system diagram showing a ventilation system in the steam power generation facility of the second embodiment.
In the ventilation system of Example 2, a denitration reactor 10 and a denitration ventilator (DNF) 11 are arranged particularly downstream of the exhaust gas system E of the furnace 1.
The denitration reactor 10 is a reactor disposed between the furnace 1 and the air preheater 5. The denitration reactor 10 is a reactor that removes nitrogen oxides (NOx) in the exhaust gas system E.

  Further, the exhaust gas e of the exhaust gas system E between the denitration reactor 10 and the furnace 1 can be denitrated with ammonia.

  A denitration ventilator (DNF) 11 is disposed downstream of the air preheater 5. This denitration ventilator (DNF) 11 compensates for the windage loss in the exhaust gas system E.

  Further, in the exhaust gas system E, it is preferable to arrange a desulfurization reactor (not shown) and a desulfurization ventilator (not shown) downstream thereof in order to remove sulfur oxides (SOx).

  Note that the present invention can improve the thermal efficiency of ventilation by changing the equipment arrangement in the ventilation system, and can improve the removal efficiency of sulfur / nitrogen oxides (SOx, NOx), ash particles, etc. in the exhaust gas. Of course, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  The ventilation system in the steam power generation facility of the present invention can be used for a combined cycle power generation facility in addition to the steam power generation facility.

It is a systematic diagram which shows the ventilation system in the steam power generation equipment of Example 1. FIG. It is a systematic diagram which shows the ventilation system in the steam power generation equipment of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 2 Chimney 3 Push-in ventilator 4 Steam-type air heater 5 Air preheater 6 Gas recirculation ventilator 7 Gas recirculation booster fan 8 Electric dust collector 9 Damper device 10 Denitration reactor 11 Denitration ventilator a Air e Exhaust gas A Air System E Exhaust gas system

Claims (6)

Steam power generation facility comprising an air system (A) and an exhaust gas system (E) for supplying air (a) necessary for combustion in the furnace (1) after being heated and heated by the exhaust gas (e) The ventilation system in
A forced draft fan (3) for taking outside air (a) and pushing it into the furnace (1) as combustion air;
An air preheater (5) for exchanging heat with residual heat of the exhaust gas system (E) from the furnace (1) in order to heat the air (a) taken in by the forced air ventilator (3) to about 200 ° C. ,
An electrostatic precipitator (8) for collecting ash particles in the exhaust gas (e) heat-exchanged by the air preheater (5) before blowing them to the chimney (2). Ventilation system in the facility. Between the exhaust gas system (E) downstream of the furnace (1) and between the air preheater (5) and the air system (A) of the furnace (1),
The ventilation system in the steam power generation facility according to claim 1, wherein a gas recirculation ventilator (6) for adjusting a gas recirculation amount and varying a heat absorption rate of the furnace (1) is disposed. Downstream of the gas recirculation ventilator (6) and between the air preheater (5) and the air system (A) of the furnace (1),
A gas recirculation booster fan (7) for reducing the nitrogen oxide (NOx) in the exhaust gas (e) and heating the air (a) from the air preheater (5) is disposed. The ventilation system in the steam power generation facility of Claim 2. Between the push ventilator (3) and the air system (A) of the air preheater (5),
A steam type air heater (4) that heats the air (a) taken from the forced draft fan (3) from room temperature to about 100 ° C by heat exchange of auxiliary steam from the boiler or steam from the turbine is arranged The ventilation system in the steam power generation facility according to claim 1. Between the furnace (1) and the exhaust gas system (E) of the air preheater (5),
The ventilation system in the steam power generation facility according to claim 1, wherein a denitration reactor (10) for removing nitrogen oxides (NOx) in the exhaust gas (e) is disposed.   The ventilation system in the steam power generation facility according to claim 1, wherein a denitration ventilator (DNF) (11) is disposed downstream of the exhaust gas system (E) of the air preheater (5).

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