KR20020041966A - Apparatus And Method For Maintaining Constant Velocity Of Cyclone Inlet Gas In A Circulating Fluidized Bed Combustor And Incinerators - Google Patents

Abstract

PURPOSE: An apparatus and a method for constantly maintaining the flux of cyclone gas are provided to improve the collecting efficiency of a cyclone and to stabilize the operating condition of a combustor or an incinerator by constantly maintaining an inlet of the cyclone. CONSTITUTION: Combustion gas is generated from a combustor. A cyclone(20) is provided to separate and collect fine particles from combustion gas generated from the combustor. The fine particles collected by the cyclone are recirculated to the combustor by a recirculation device. A flow rate control damper(70) is installed between the combustor and the cyclone(20). The flow rate control damper(70) is operated by receiving a control signal from an operational control section(100). The operational control section(100) has a predetermined optimum pressure value therein. The operational control section(100) is connected to a monitoring section(110).

Description

Apparatus And Method For Maintaining Constant Velocity Of Cyclone Inlet Gas In A Circulating Fluidized Bed Combustor And Incinerators}

The present invention relates to an apparatus and a method for maintaining a constant cyclone inlet gas flow rate of a circulating fluidized bed combustion furnace and an industrial incinerator, and more particularly, to a gas at a cyclone inlet forming a particle collector in an industrial combustion furnace or a reburn apparatus of a combustion furnace. An apparatus for maintaining a constant cyclone inlet gas flow rate in a circulating fluidized bed combustor and an industrial incinerator, by controlling the pressure and flow rate to be kept constant at all times, thereby improving the efficiency of collecting particulates and maintaining the stability of combustion furnace operation. It is about a method.

In general, industrial incinerators and power plant combustion furnaces are equipped with a circulating fluidized bed recirculation system for improving thermal efficiency and saving fuel consumption.

The circulating fluidized bed recirculation system largely separates them by collecting a combustion furnace (1), a combustion gas generated in the combustion furnace, and unburned fuel, which burns powdered fuel such as pulverized coal and the like, as shown in FIG. It is divided into the cyclone (2), the recirculation device (3) for re-feeding the unburned dust collected from the cyclone (2) to the combustion furnace, and the after-heat transfer unit (4) for generating steam by the heat of the combustion gas ) And a baghouse 5 for collecting residual dust of the combustion gas and a chimney 6 for discharging the cooled combustion gas into the atmosphere.

The circulating fluidized bed recirculation system configured as described above enters the cyclone (2) which forms the particle collector by raising the combustion gas and unburned dust combusted in the combustion furnace (1), and in the cyclone (2) In the combustion furnace (1) to collect and separate the unburned fine powder that has not been burned, the unburned dust is transferred back to the combustion furnace (1), the combustion gas is transferred to the after-heat transfer section (4) and the post-heat transfer section (4) that generates substantial power ) Generates a large amount of steam by the hot gas heat introduced.

As such, the combustion gas and the dust with heat generating steam are cooled during the transfer process, and the dust is collected in the bag house 5, and the remaining combustion gas finally removes the chimney 6. It is equipped with a series of recirculation system which discharges to the atmosphere.

In particular, the cyclone's ability to capture unburned particles and separate them from the combustion gases has a significant impact in terms of thermal efficiency and stabilization of the combustion furnace and incinerator using a circulating moving bed system. It is desirable that the minute and combustion gases always have a constant flow rate and pressure.

That is, if the combustion gas introduced into the cyclone 2 having the spiral passage therein does not have a constant flow rate, the pressure of the combustion gas vortexing inside becomes uneven and the dust collection performance is deteriorated.

Here, the principle of the cyclone (2) that performs the function of the particle collector is that the particles (fine dust) discharged from the combustion furnace tangentially flows into the vortex-shaped passageway in the cyclone and moves along the vortex formed inside the wall surface. Particles that have mass under centrifugal force and drag force in tangential direction are separated.

At this time, if the diameter of the particle is dp, the density is Pp, and the radius in the cyclone is r, the centrifugal force (Fc) falling on the particle flowing at the tangential velocity Vi is as follows.

The relationship of (1) is formed, and if the particles If you move at a speed of, the drag on the particle (Fd) The relationship of (2) is formed. here Represents the viscosity of the exhaust gas.

In normal condition Therefore, the following equation can be obtained from equations (1) and (2).

(3)

In the ideal case, all particles moved to the wall are collected, so the cyclone collection efficiency is determined by Is directly proportional to Can be used as an indicator of cyclone collection efficiency.

That is, as can be inferred from Equation (3), the collection efficiency of the cyclone is the injection speed. As increases the particle size The larger the particle density It can be seen that the larger, the smaller the diameter of the cyclone, the higher the viscosity is increased.

On the other hand, energy losses in the cyclone are mostly pressure drops and are directly related to the operating costs of the reburn system.

The cause of the pressure drop can be divided into kinetic energy loss of the vortices formed in the cyclone, friction, and loss due to expansion and contraction of the gas at the inlet, and there are many factors that directly affect the pressure drop. And the area difference of the outlet, the inflow velocity, the length of the body, the depth of the inlet duct, the temperature of the fluid and the like.

The relation of the pressure drop can be represented by the following equation, where Denotes the velocity of gas entering the cyclone and C denotes a constant value .

(4) (caplan, 1968)

As shown in Eq. (4), as the inflow rate increases, the pressure also increases, so that the finer particles can be collected, thereby increasing the collection efficiency.

Therefore, according to the given design requirements, an optimum design is required to satisfy both pressure drop and collection efficiency.

Figure 2 is an example showing a conventional general cyclone, inlet flow rate of 15 to 25m / sec , the pressure drop is selected to a suitable value within the range of 150 ~ 200mmAq to the inlet width (b) diameter of the cyclone to satisfy the conditions (Dc) and so on, each standard is determined, and once manufactured and installed, the cyclone (2) cannot change the standard in that state in any way.

However, the operation of a furnace using a circulating fluidized bed system is not always operated under constant conditions and is often operated while varying the load factor in relation to the thermal efficiency of the required industrial incinerator or the furnace.

In other words, when the load rate is increased, the fuel and air supply amount is increased to increase the flow rate and pressure of the cyclone inlet, whereas when the load rate is reduced, the amount of fuel supplied is reduced and the air amount is reduced to decrease the cyclone inlet flow rate and pressure. In addition, the size of the fuel particles to be supplied is continuously worn down and reduced in the course of combustion through the closed circulation system.

Although the shape of the cyclone 2 inlet is constant, the inlet gas and particle conditions vary according to the operating conditions of the furnace, so the collection efficiency of the cyclone is out of the fixed cyclone conditions and recycled. This will have a direct negative impact on the efficiency of the system.

The present invention has been devised in view of the above problems, and an object of the present invention is to ensure that the load ratio of the combustion furnace in the industrial circulating fluidized bed recirculation system of the incinerator or combustion furnace does not depart from the range applying the cyclone inlet condition. An apparatus and method for maintaining a constant cyclone inlet gas flow rate of a circulating fluidized bed combustor and an industrial incinerator which not only improves the collection efficiency of the cyclone by maintaining it constant but can also provide stable operating conditions to an industrial incinerator or a combustion furnace It is to offer.

1 is a block diagram showing a conventional circulating fluidized bed combustion furnace and industrial incinerator apparatus,

2 is a view showing the form of a cyclone forming a part of a conventional circulating fluidized bed combustion furnace and industrial incinerator,

Figure 3 is a schematic view showing a circulating fluidized bed combustion furnace and industrial incinerator apparatus to which the present invention is applied,

FIG. 4 is a schematic view of a cyclone inlet duct forming the main components of the present invention in FIG.

5 is a view showing an embodiment of a flow control damper for load control that can be represented by the cross-section 'A-A' of FIG.

Figure 6 is a flow chart that can implement the cyclone inlet gas constant pressure maintaining method of the circulating fluidized bed combustion furnace and industrial incinerator apparatus according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: combustion furnace 20: cyclone

30: recirculation device 40: rear heat transfer unit

50: Bag house 60: Stack

70: flow control damper 71: actuator

72: rotating shaft 72a: hollow passage

73: flow control plate 74: cavity (cavity)

80: pressure measuring instrument 90: differential pressure signal conversion transmitter

100: operation control unit 110: monitoring unit

D: Duct

In order to achieve the above object, the present invention is an industrial incinerator or combustion furnace for burning a fuel to produce a hot gas; A cyclone connected to the combustion furnace to separate the unburnt and the combustion gas that have not been combusted in the combustion furnace; In the circulation system consisting of a recirculation device for supplying the separated fine dust to the combustion furnace,

A flow control damper installed between the combustion furnace and the cyclone particle collector to maintain a constant flow rate and flow rate in response to a change in flow rate and flow rate according to the operating conditions at the inlet of the cyclone; Two or more pressure measuring spheres connected between the flow control damper and the cyclone to measure inlet and outlet pressure of the cyclone;

A differential pressure signal conversion transmitter for converting an analog signal measured by the two or more pressure measuring instruments into a digital signal and outputting the same to an operation control unit; An arithmetic and control unit which compares and analyzes the digital value of the differential pressure applied by the differential pressure signal conversion transmitter with a predetermined set value and transmits a control signal for driving the flow control damper if it is out of the range; It characterized in that it comprises a monitoring unit for storing data while monitoring the value input and output from the operation control unit.

Another feature of the present invention is an industrial incinerator or combustion furnace that burns fuel to produce hot gases; A cyclone connected to the combustion furnace to separate the unburnt and the combustion gas that have not been combusted in the combustion furnace; In the circulation system consisting of a recirculation device for supplying the separated fine dust to the combustion furnace,

Measuring the pressure of the cyclone inlet-side combustion gas and measuring the pressure of the cyclone-outlet side combustion gas; And calculating the difference value calculated by the differential pressure signal conversion transmitter and comparing the preset pressure value to the inside of the operation control unit, and adjusting the flow rate when the pressure value is outside the predetermined pressure value in the operation control unit. Transmitting a control signal to the damper; and controlling the opening and closing operation of the cyclone inlet by the control signal sent from the operation control unit. And measuring again to determine whether it is within a range of allowable pressure values in the calculation control unit: again measuring the inlet and outlet pressures of the cyclone. If the measurement result is included in the allowable pressure value was made to include the step of maintaining the opening and closing rate of the flow control damper.

Hereinafter, with reference to the accompanying drawings an embodiment that can meet the above objects and features in the best form is described in detail as follows.

3 and 4 is a configuration diagram showing a circulating fluidized bed combustion furnace and an industrial incinerator apparatus to which the present invention is applied, which may represent the general configuration and features of the present invention.

Apparatus to which the present invention is applied is a combustion furnace (10) that burns large fuel to generate combustion gas, a cyclone (20) which separates and collects fine dust from the combustion gas generated in the combustion furnace, and the unburnt collected from the cyclone. It is roughly divided into a recirculation apparatus 30 for feeding the powder back to the combustion furnace, and the part to which the present invention is applied is made between the combustion furnace 10 and the cyclone 20.

That is, the flow control damper 70 is installed between the combustion furnace 10 and the cyclone 20, the driving of the flow control damper 70 is operated by the control signal sent from the operation control unit 100, The optimum pressure value is set in the control unit 100 itself in a predetermined range and the operation control unit 100 is connected to the monitoring unit 110 made of a personal computer (PC) so that the operator can observe again.

The mechanical configuration of the flow control damper 70 may be shown as a specific example as shown in FIGS.

A flow regulating damper 70 of combustion gas is installed between the duct D and the inlet of the cyclone 20, and the structure of the flow regulating damper 70 is an actuator 71 for generating a driving force by an electrical signal. And a rotation shaft 72 structurally connected to the actuator 71, and a flow control plate 73 integrally structured with the rotation shaft 72.

Here, the flow control plate 73 is formed in a plate shape on both sides of the rotation shaft 72 and the inside of the rotation shaft 72 of the flow control damper 70 so that the flow control plate 73 is not deformed by heating due to high temperature combustion gas. The hollow passage 72a of the cooling water is formed and the flow control plate 73 forms a cavity 74, which is divided into a plurality of spaces, and the hollow passage 72a of the rotation shaft 72 into the plurality of spaces. Branched cooling water passages are connected.

The flow control plate 73 is also rotatably supported in the inner space of the duct (D), where the shape of the inner cross section of the duct (D) has a rectangular or square shape.

Meanwhile, the flow rate of the combustion gas and the exit of the cyclone 20 into which the combustion gas is introduced

A pressure measuring device 80 for measuring the pressure by the flow rate is installed, and another pressure measuring device 80 is installed in the duct D space between the flow control damper 70 and the cyclone 20. .

The pressure measuring device 80 installed in the duct D space between the flow control damper 70 and the cyclone 20 is called the first pressure measuring device 81 and the pressure measuring device 80 installed at the cyclone outlet. If the second pressure measuring sphere (82) is the pressure difference by the combustion gas is formed by the variable operation of the combustion furnace 10 between the space in which they are installed, the pressure difference is measured by the first pressure measuring sphere (81) The differential pressure signal conversion transmitter 90 connected between the two pressure measuring instruments 82 measures them and converts them into digital values.

The flow control damper 70 and the differential pressure signal conversion transmitter 90 having the above-described mechanical configuration are electrically connected to the operation control unit 100 forming the digital control unit and set to an optimum pressure allowance set inside the operation control unit 100. In contrast, the control signal is transmitted to the actuator 71 of the flow control damper 70 so that the pressure applied from the differential pressure signal conversion transmitter 90 is maintained within the tolerance.

The actuator 71 provides a driving force for operating the flow control plate 73 of the flow control damper 70 and tilts the flow control plate 73 at a predetermined angle inside the duct D of the cyclone 20 inlet. It also has a function of tilting.

The tilting angle is set at various times depending on the flow rate of the combustion gas flowing into the cyclone 20 inlet and is actively changed according to the load ratio of the combustion furnace.

As can be seen from the structure according to the above embodiment, the control of the actual flue gas flow rate and pressure introduced into the cyclone inlet 20 from the inside of the duct D is controlled by the opening and closing rate of the duct D inside the cyclone inlet. The present invention can be achieved by the above apparatus can achieve the object.

However, the present invention is not limited to the opening and closing rate of the passage by the flow control plate 73, and any type of mechanical structure can be implemented by another embodiment as long as it can adjust the opening and closing rate of the passage by the actuator 71. Could be.

On the other hand, the operation control unit 100 is connected to the monitor unit 110 that allows the operator to monitor the flow rate adjustment state, the form of such a monitoring unit 110 in the present invention forms the display unit 110 by a personal computer It stores the digital numerical data of the pressure at the cyclone inlet and the differential pressure, which is confirmed by the differential pressure signal conversion transmitter.

A method that can be implemented by the apparatus of the present invention having the above configuration will be described below with reference to FIG. 6.

First, measuring the pressure of the cyclone inlet combustion gas (S10) and: measuring the pressure of the cyclone outlet combustion gas (S20) and: receiving the values of the cyclone inlet and outlet pressures Computing the difference value in the differential pressure signal conversion transmitter (S30) and: The difference value calculated by the differential pressure signal conversion transmitter is received and contrasted with a predetermined set pressure value into the operation control unit (S40): (S50) and transmitting the control signal to the flow control damper when the pressure value is out of the predetermined pressure value in the control unit: the flow control damper performs the opening and closing operation of the cyclone inlet by the control signal sent from the operation control unit ( S60) and: after the opening and closing operation of the flow control damper again measuring the inlet and outlet side pressure of the cyclone to determine whether it is in the range of the allowable pressure value in the calculation control unit (S70) and: the cycle When the inlet and the outlet includes a back pressure to the measurement results allow the pressure value comprises a step (S80) for holding the opening and closing rate of the flow rate adjustment damper

According to the method of the present invention as described above, the flow regulating damper actively maintains a constant pressure state in response to the pressure change at the cyclone inlet by the variable operation of the combustion furnace or the industrial incinerator.

In the above case, the step of comparing with the preset pressure value set inside the operation control unit (S30). And transmitting a control signal to the flow control damper when the pressure value is out of the predetermined pressure value at the calculation control unit (S40) and: controlling the opening and closing operation of the cyclone inlet by the control signal sent from the calculation control unit. In step S50, they exchange information with each other and have a form of a closed loop that maintains a constant value with each other, and maintains a constant flow rate and pressure of the cyclone inlet.

As described above, the present invention provides a measuring apparatus capable of measuring the pressure by the flow rate and the amount of the combustion gas at the cyclone inlet for collecting and re-feeding the fine dust generated in the industrial incinerator or the combustion furnace and this It is connected to the internally set optimal setting value and the flow control damper is installed to control the flow rate and flow rate of the combustion gas, so even if the operating load rate varies in an industrial incinerator or combustion furnace using a circulating fluidized bed It is kept constant so that it does not deviate from the application of the cyclone inlet condition.

Therefore, according to the present invention, by forming a constant combustion gas inlet condition of the cyclone inlet, it is possible to not only improve the collection efficiency of fine dust but also to provide more stable operating conditions in the combustion furnace and incinerator using the circulating fluidized bed.

Claims (4)

A combustion furnace that burns fuel to produce hot gases; A cyclone connected to the combustion furnace to separate the unburnt and the combustion gas that have not been combusted in the combustion furnace; In the circulation system consisting of a recirculation device for supplying the separated fine dust to the combustion furnace, A flow control damper installed between the combustion furnace and the cyclone particle collector to maintain a constant flow rate and flow rate in response to a change in flow rate and flow rate according to the operating conditions at the inlet of the cyclone; Two or more pressure measuring spheres connected between the flow control damper and the cyclone to measure inlet and outlet pressure of the cyclone; A differential pressure signal conversion transmitter for converting an analog signal measured by the two or more pressure measuring instruments into a digital signal and outputting the same to an operation control unit; An arithmetic and control unit which compares and analyzes the digital value of the differential pressure applied by the differential pressure signal conversion transmitter with a predetermined set value and transmits a control signal for driving the flow control damper if it is out of the range; Apparatus for maintaining the cyclone inlet gas flow rate of the circulating fluidized bed combustion furnace and industrial incinerator characterized in that it comprises a monitoring unit for storing data while monitoring the value input and output from the operation control unit. The actuator of claim 1, further comprising: an actuator configured to set a rotation angle while imparting a driving force by an electric control signal; A circulating fluidized bed comprising a flow control plate integrated in a plate shape on a rotating shaft structurally connected to an actuator, the flow control plate rotating inside the duct of the cyclone inlet to set the opening and closing rate of the incoming gas by a set rotation angle. Apparatus for maintaining a constant cyclone inlet gas flow rate in combustion furnaces and industrial incinerators. According to claim 2, wherein the rotating shaft of the flow control damper to form a hollow passage of the cooling water and the flow control plate to form a cavity (cavity) is divided into a plurality of spaces again, branched from the hollow passage of the rotating shaft into the plurality of spaces A device for maintaining a constant cyclone inlet gas flow rate in a circulating fluidized bed combustor and an industrial incinerator, characterized in that a cooling water passage is connected. A combustion furnace that burns fuel to produce hot gases; A cyclone connected to the combustion furnace to separate the unburnt and the combustion gas that have not been combusted in the combustion furnace; In the circulation system consisting of a recirculation device for supplying the separated fine dust to the combustion furnace, Measuring the pressure of the cyclone inlet-side combustion gas and measuring the pressure of the cyclone-outlet side combustion gas; And calculating the difference value calculated by the differential pressure signal conversion transmitter and comparing the preset pressure value to the inside of the operation control unit, and adjusting the flow rate when the pressure value is outside the predetermined pressure value in the operation control unit. Transmitting a control signal to the damper; and controlling the opening and closing operation of the cyclone inlet by the control signal sent from the operation control unit. And measuring again to determine whether it is within a range of allowable pressure values in the calculation control unit: again measuring the inlet and outlet pressures of the cyclone. Method of maintaining the cyclone inlet gas flow rate of the circulating fluidized bed combustor and industrial incinerator characterized in that it comprises the step of maintaining the opening and closing rate of the flow control damper if the measurement result is included in the allowable pressure value.