KR20100020084A - Gas-air mixing apparatus for boiler - Google Patents

Abstract

PURPOSE: A gas-air mixing device for a boiler is provided to make a high turndown ratio by consecutively changing the amount of gas fuel mixture. CONSTITUTION: A gas-air mixing device for a boiler comprises a gas pipe(142), and an up and down movement member(150) and a side to side movement member(160). The gas pipe is installed on the upper side of an impeller(110). The gas is emitted from the gas pipe. The up and down movement member controls the gas eruption amount of the gas pipe outlet as the relative distance with the gas pipe outlet is varied due to the rotation of the impeller. The side to side movement member is getting apart and closer from and to a rotary shaft by centrifugal force. A guide hole is formed on the side to side movement member.

Description

Gas-air mixing apparatus for boiler

The present invention relates to a gas-air mixing apparatus of a boiler, and more particularly, to a gas-air mixing apparatus capable of improving the turndown ratio of a burner in a boiler in which gas and air are mixed and supplied to a burner for combustion. .

In general, a turn-down ratio (TDR) is set for a gas boiler. The turndown ratio (TDR) refers to the ratio of maximum gas consumption to minimum gas consumption in a gas combustion device in which the amount of gas is variably controlled. The turndown ratio (TDR) is limited by how low the minimum gas consumption can be adjusted to maintain a stable flame.

In the case of gas boilers, the greater the turndown ratio (TDR), the greater the convenience of using heating and hot water. In other words, when the burner is operated in an area where the turndown ratio (TDR) is small (that is, when the minimum gas consumption is high) and the load of heating and hot water is small, frequent boiler on / off occurs. The deviation at the time of control becomes large and durability of an apparatus falls. Therefore, a method of improving the turndown ratio (TDR) of the burner applied to the gas boiler has been proposed.

The output of the boiler is represented by the equation

In order to operate the boiler in the low power range by increasing the turndown ratio, the gas pressure must be lowered, but the gas pressure must be maintained above a certain pressure in consideration of the error of the gas supply pressure and the characteristics of the gas supply valve. There is a limit to improving.

An international application (PCT / EP2007 / 009516) has been published to address these issues. 1 is a block diagram showing a gas-air mixing device disclosed in the above international application, Figure 2 is a graph showing the output implemented by the structure shown in FIG.

Referring to FIG. 1, the gas-air mixing device 1 includes a burner 2, an air pipe 3 through which air is introduced, an air orifice 3a for adjusting the flow rate of the air introduced therein, and a gas. Gas pipe 4 into which gas is introduced, gas orifice 4a for adjusting the flow rate of the gas being introduced, gas valve 7 for adjusting the flow rate of gas by measuring the pressure of the air pipe 3, and gas and A blower 6 for supplying a mixture of air to the burner 2.

The air orifice 3a and the gas orifice 4a have a structure in which the degree of opening varies according to the output required by the boiler.

According to the gas-air mixing apparatus 1 of FIG. 1, as shown in the graph of FIG. 2, the gas-air mixing apparatus 1 is divided into a high power region (turndown ratio C ′ = 1: 5) and a low power region (turndown ratio C ″ = 1: 5). A down ratio of 1:10 (C '+ C ") is achieved.

That is, FIG. 2 shows the relationship between the rotation speed N of the blower 6 and the output P of the boiler. Here, Sa 'and Sa "represent the cross-sectional area of the air orifice 3a at high power and low power, and Sg' and Sg" represent the cross-sectional area of the gas orifice 3b at high power and low power, respectively.

In the high power region, the air orifice 3a and the gas orifice 3b are set to Sa 'and Sg' to adjust the rotation speed of the blower 6 to realize a turndown ratio C '= 1: 5, and in the low power region, the air orifice The cross-sectional area of 3a and gas orifice 3b is reduced to achieve a turndown ratio of C " = 1: 5 in the state of Sa " and Sg ".

However, the gas-air mixing device is composed of two stages, a low output region and a high output region. In order to change the output, not only the rotational speed of the blower 6 but also the cross-sectional area of the orifice must be changed. There is a disadvantage in that the movement to and from the high output area to the low output area is not smooth.

In addition, since the gas valve 7 shown in FIG. 1 needs to use a special valve for controlling the pressure at the front end of the gas orifice 3b by receiving the feedback of the pressure at the front end of the air orifice 3a, the gas valve 7 is generally used for supplying gas. There is a problem that an on-off valve or an electric proportional control valve cannot be used.

In addition, there is a problem in that the structure of the device is complicated because a separate driving device is required to change the areas of the orifices 3a and 3b of gas and air.

The present invention has been made to solve the above-mentioned problems, the gas-air mixing apparatus of the boiler that can realize a high turndown ratio by continuously changing the amount of the gas-fuel mixture supplied at high power and low power while having a simple structure The purpose is to provide.

In the present invention for achieving the above object, in the gas-air mixing device for supplying a mixture of gas and air to the burner by the blower, the gas blowing area is adjusted by the centrifugal force change according to the change of the impeller rotation angular velocity of the blower It is characterized by.

In this case, the gas pipe is installed on the upper side of the impeller to eject the gas; And a moving member for adjusting the gas ejection amount of the gas pipe outlet by changing the relative distance from the gas pipe outlet by the rotation of the impeller.

According to the present invention, it is possible to continuously change the amount of the gas-fuel mixture supplied under a constant gas pressure to achieve a high turndown ratio.

In addition, since the gas-fuel mixture is formed in proportion to the angular velocity of the impeller, accurate control can be made smoothly when the output is to be changed in the high power and low power areas.

In addition, the supply of gas can be controlled by using a general on-off valve or a proportional control valve without using a special valve to supply the gas.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a cross-sectional schematic view showing a gas-air mixing device according to an embodiment of the present invention, Figure 4 (a), (b), (c), (d), (e) is a front cross-sectional view showing an impeller AA, BB, CC partial cross-sectional view, Figure 5 (a), (b) is a plan view showing a shankdong member and AA partial cross-sectional view, Figure 6 (a), (b), (c) is a plan view showing a left and right moving member And front view and AA cross-sectional view, Figure 7 is a plan view and a cross-sectional view showing a gas pipe fixing member, Figure 8 is a schematic view showing the guide groove shape of the left and right moving member.

The gas-air mixing device 100 of the present invention has a structure for mixing gas and air in a blower for supplying a gas-air mixture to the burner side.

That is, the present invention, the impeller 110 for supplying the gas-air mixture to the burner side by the drive of the motor 120, the blower upper housing 131 and the lower housing surrounding the outside of the impeller 110 ( 132, a gas pipe 142 installed at an upper side of the impeller 110, a gas pipe fixing member 141 fixing the gas pipe 142, and a gas pipe outlet 142a by rotating the impeller 110. Relative distance from the variable is generated when the impeller 110 to move up and down the shankdong member 150, the shankdong member 150 for adjusting the amount of gas ejected through the gas pipe outlet (142a) It is composed of a left and right moving member 160 is moved away from or close to the rotation axis 121 by the centrifugal force.

The impeller 110 is connected to the motor 120 by the rotation shaft 121, the motor 120 is coupled to the lower surface of the blower lower housing 132. The mixture of air and gas is supplied to the burner side by the rotation of the impeller 110.

In the inner space surrounded by the upper housing 131 and the lower housing 132, an impeller 110, a shank moving member 150, and a left and right moving member 160 are installed. A mixture discharge port 133 is formed between one end of the upper housing 131 and one end of the lower housing 132 so that the mixture of air and gas is discharged to the burner side. The motor 120 is installed on the lower surface of the lower housing 132.

The left and right moving members 160 are elastically supported by the spring 170.

The gas supplied through the gas pipe 142 is controlled by a conventional on-off valve or an electric proportional control valve.

The impeller 110 will be described with reference to FIG. 4.

The impeller 110 is provided with a wing 111 to induce air blowing during rotation, and the upper surface of the central portion is formed with a cylindrical insertion shaft 112 protruding to a predetermined length. The movable member 150 is inserted into the insertion shaft 112.

The guide parts 113 and 114 having a 90 degree upper end of the cross section with the insertion axis 112 in the center are protruded from the upper surface.

First guide portions 113a and 113b are formed above and below the insertion shaft 112. The flange portions 162b and 163b of the left and right moving members 160 are inserted into the inner grooves 113c and 113d of the first guide portions 113a and 113b (see FIG. 6). The left and right moving members 160 are moved while being guided along the longitudinal direction of the grooves 113c and 113d.

In addition, a second guide portion 114 having a '⊃' shape is formed at a right side of the insertion shaft 112. The weight portion 161 (see FIG. 6) of the left and right moving members 160 is inserted into the inner groove 114a of the second guide portion 114.

Referring to Figure 5 will be described with respect to the movable member 150.

Shanghai copper member 150 is to adjust the amount of gas ejected through the ejection port 142a of the gas pipe 142 as the position is changed in the vertical direction when the impeller 110 is rotated.

The shankdong member 150 is composed of a cylindrical body 151 having an empty space 153 therein and guide shafts 152a and 152b protruding from both sides of the body 151.

The insertion shaft 112 of the impeller 110 is inserted into the space 153 inside the body 151 to guide the vertical movement of the shank moving member 150.

The guide shafts 152a and 152b are inserted into the guide grooves 162a and 163a of the left and right moving members 160 to determine the vertical position of the shank moving member 150 according to the positions of the left and right moving members 160.

The left and right moving members 160 will be described with reference to FIG. 6.

The left and right moving members 160 are raised or lowered by moving the moving member 150 by moving away from or near the rotating shaft 121 of the motor 120 by the centrifugal force during the rotation of the impeller 110.

The left and right moving members 160 have a weight part 161 for generating centrifugal force that can vary the position of the shank moving member 150 when the impeller 110 is rotated, and the impeller (when moving in the left and right directions). It consists of a guide body (162, 163) guided by the first guide portion 113 of (110).

The guide bodies 162 and 163 are formed with arc-shaped guide grooves 162a and 163a into which the guide shafts 152a and 152b of the shandong copper member 150 are inserted. The lower ends of the guide bodies 162 and 163 protrude in the lateral direction. Flange portions 162b and 163b are formed.

The guide grooves 162a and 163a are formed to have different heights at one end and the other end, thereby regulating the vertical positions of the guide shafts 152a and 152b of the shankdong member 150.

The gas pipe fixing member 141 will be described with reference to FIG. 7.

The gas pipe fixing member 141 has a gas pipe insertion hole 141a into which the gas pipe 142 jet port 142a is inserted and fixed to fix the gas pipe 142 into which the gas is introduced, and the gas pipe insertion hole 141a is formed. Is supported by the support 141b. Air mixed with gas flows in through the space 141c between the support 141b.

The shape of the guide grooves 162a and 163a of the left and right moving members 160 will be described with reference to FIG. 8.

The guide grooves 162a and 163a are configured to move the shank moving member 150 in proportion to the rotational angular velocity of the impeller 110.

When the impeller 110 is stopped, the distance from the rotating shaft 121 to the center of gravity of the left and right moving member 160 is a, and the impeller 110 rotates the moving distance of the left and right moving member 160 when rotating at an angular velocity of w, If the mass of the left-right moving member 160 is m and the constant of the spring 170 is k, the following equation is established.

가 된다.In other words,

Becomes

When the moving distance of the left and right moving members 160 is ｘ ₁ , ｘ ₂ , the moving distances L ₁ and L ₂ of the Shanghai moving members 150 are as follows.

(α: proportionality constant)

Therefore, the moving distances (ｘ ₁ , ｘ ₂ ) of the left and right moving members 160 are proportional to the square of the angular velocity, and form the shape of the guide grooves 162a and 163a of the left and right moving members 160 as shown in FIG. 8. If so, the vertical movement distance of the shankdong member 150 is proportional to the angular velocity.

Hereinafter, the operation of the gas-air mixing device of the present invention having the above configuration will be described.

9 is an operating state showing the position of the shank and the left and right moving members at low power, Figure 10 is a state diagram showing the position of the shank and left and right moving members at high power.

In the low power region of FIG. 9 and the high power region of FIG. 10, the pressure of the gas supplied through the gas pipe 142 is kept constant.

When the impeller 110 rotates at a low speed by the operation of the motor 120, the left and right moving members 160 slightly move in the circumferential direction while winning the elastic force of the spring 170. In this case, the shank moving member 150 is slightly lowered along the guide grooves 162a and 163a of the left and right moving members 160, so _that the distance (L _low ) between the gas pipe outlet 142a and the upper end of the shandong moving member 150 is lower. _Rotation ) is in a small state.

At this time, the gas supply amount is proportional to the gas passing area formed between the gas pipe outlet 142a and the upper end of the shandong copper member 150, and the relation is as follows.

Gas passage area = D · π · L _{low rotation} (D: inner diameter of gas pipe outlet 142a)

In addition, when the impeller 110 rotates at a high speed by the operation of the motor 120, the left and right moving members 160 largely move in the circumferential direction while winning the elastic force of the spring 170. In this case, the shank moving member 150 descends a lot along the guide grooves 162a and 163a of the left and right moving members 160, so that the distance between the gas pipe outlet 142a and the upper end of the shandong moving member 150 is _high (L _rotation). ) Is in a large state.

At this time, the gas supply amount is proportional to the gas passing area formed between the gas pipe outlet 142a and the upper end of the shandong copper member 150, and the relation is as follows.

Gas passage area = D · π · L _{high rotation} (D: inner diameter of gas pipe outlet 142a)

11 is a graph showing the relationship between the impeller angular velocity, the distance between the shank moving member and the gas pipe outlet, FIG. 12 is a graph showing the relationship between the impeller angular velocity and the gas supply amount, and FIG. 13 is a graph showing the relationship between the impeller angular velocity and the air supply amount. 14 is a graph showing the relationship between the impeller angular velocity and the gas / air mixing ratio, and FIG. 15 is a graph showing the relationship between the impeller angular velocity and the burner output.

As described with reference to FIG. 8, when the shape of the guide grooves 162a and 163a of the left and right moving members 160 is formed so that the vertical movement distance of the shank moving member 150 is proportional to the angular velocity, as shown in FIG. The distance between the 150 and the gas pipe outlet 142a is proportional to the angular velocity of the impeller 110.

In this case, as shown in FIGS. 12 and 13, as the angular velocity of the impeller 110 increases, the gas supply amount and the air supply amount increase in proportion.

On the contrary, as shown in FIG. 14, the gas / air mixture ratio is constantly maintained despite the change in the angular velocity of the impeller 110, so that an appropriate gas-air ratio may be realized at all times.

In addition, since the vertical movement distance of the shankdong member 150 is proportional to the angular velocity, the output of the burner is also proportional to the angular velocity of the impeller 110 as shown in FIG. Therefore, there is an advantage that can accurately control the desired output only by the change in the angular velocity of the impeller 110.

In addition, since the gas pressure is kept constant in the low power area as in the high power area, only a change in the number of revolutions of the impeller 110 enables stable combustion in a wide load area from low power to high power, thereby achieving a high turndown ratio. have.

In addition, when the load is changed from the high output region to the low output region, the change of the orifice cross-sectional area is not necessary as in the prior art, so that the load change can be made smoothly.

In addition, as in the prior art, it is not necessary to use a special valve that adjusts the gas pressure by receiving the pressure of the front end of the air orifice.

In the above description, the embodiment in which one left and right moving member 160 and the spring 170 are provided has been described. In this case, the left and right moving member 160 and the shank moving member 150 are supported during rotation of the impeller 110. Since it depends on one spring 170, vibration may occur.

Accordingly, as shown in FIG. 16, at least one other left and right moving member 180 in a position (for example, 180 degree symmetrical position) that can cancel the force of the spring 170 supporting the left and right moving member 160. ) And a spring 190 for elastically supporting the same, wherein the left and right moving members 150 are symmetrically supported by both the left and right moving members 160 and 180 and the springs 170 and 190. It is preferable. Reference numeral 183a denotes a guide groove formed in the left and right moving members 180.

As described above, the present invention has been described using embodiments, but these embodiments are merely exemplary, and those skilled in the art may make various modifications and changes without departing from the spirit of the present invention. I can understand that.

1 is a block diagram showing a gas-air mixing device disclosed in the international application (PCT / EP2007 / 009516),

FIG. 2 is a graph showing output implemented by the structure shown in FIG. 1;

Figure 3 is a schematic cross-sectional view showing a gas-air mixing device according to an embodiment of the present invention,

4 (a), (b), (c), (d), (e) is a front cross-sectional view and a plan view showing the impeller and A-A, B-B, C-C partial cross-sectional view,

Figure 5 (a), (b) is a plan view showing the shandong copper member and A-A partial cross-sectional view,

Figure 6 (a), (b), (c) is a plan view and a front view showing a left and right moving member and A-A cross-sectional view,

7 is a plan view and a cross-sectional view showing a gas pipe fixing member;

8 is a schematic view showing a guide groove shape of the left and right moving members;

9 is an operation state showing the position of the shank and the left and right moving members in the case of low power,

10 is an operation state showing the position of the shank and the left and right moving members at high power,

11 is a graph showing the relationship between the impeller angular velocity and the distance between the shank copper member and the gas pipe outlet;

12 is a graph showing a relationship between an impeller angular velocity and a gas supply amount,

13 is a graph showing a relationship between impeller angular velocity and air supply amount,

14 is a graph showing the relationship between impeller angular velocity and gas / air mixing ratio,

15 is a graph showing the relationship between impeller angular velocity and burner output;

16 is a partially enlarged view showing another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100 gas-air mixing device 110 impeller

112: insertion shaft 113: first guide portion

114: second guide portion 120: motor

121: rotating shaft 131: blower upper housing

132: blower lower housing 141: gas pipe fixing member

142 gas pipe 150 Shanghai East member

151: trunk 152: guide shaft

160: left and right moving member 161: parts by weight

162, 163: guide body 162a, 163a: guide groove

170: spring

Claims (9)

In the gas-air mixing device for supplying a mixture of gas and air to the burner by a blower, Gas-air mixing device of the boiler, characterized in that the gas blowing area is adjusted by the centrifugal force change according to the change of the impeller rotation angular velocity of the blower. The method of claim 1, A gas pipe installed above the impeller to eject gas; Shanghai copper member for controlling the gas blowing amount of the gas pipe outlet by changing the relative distance to the gas pipe outlet by the rotation of the impeller; Gas-air mixing device of the boiler comprising a. The method of claim 2, Left and right moving members which are moved away from or close to the rotation axis by the centrifugal force when the impeller is rotated, and the guide groove is formed in a vertically inclined direction; A protruding guide shaft which is inserted into the guide groove is formed on the side, and the vertical moving member is moved up and down along the guide groove by the movement of the left and right moving members to adjust the gas ejection amount of the gas pipe outlet; Gas-air mixing device of the boiler comprising. The method of claim 3, The left-right moving member is a gas-air mixing device of the boiler, characterized in that the elastic support by the spring. The method of claim 4, wherein Gas-air mixing device of the boiler characterized in that it is further provided with one or more other left and right moving member and a spring for supporting it elastically in a position that can cancel the force of the spring for supporting the left and right moving member. The method of claim 3, The guide groove of the left and right moving member is a gas-air mixing device of the boiler, characterized in that for moving the movable member in proportion to the angular velocity of the impeller. The method of claim 3, A flange portion protruding laterally is formed at a lower end of the left and right moving members, and a guide part is formed at an upper surface of the impeller so that an upper end of the cross section is bent by 90 degrees to form a groove at a lower side thereof. Gas-air mixing device of the boiler, characterized in that the guide is inserted into the groove of the guide portion when moved left and right. The method of claim 2, The shank moving member is inserted into a cylindrical insertion shaft protruding on the upper surface of the impeller is a gas-air mixing device of the boiler, characterized in that the vertical position is changed along the insertion axis when the left and right moving member moves. The method according to any one of claims 3 to 8, A gas pipe fixing member in which the outlet of the gas pipe is inserted and fixed and covers the upper portion of the blower; A blower upper housing coupled to the lower end of the gas pipe fixing member such that the impeller, the shank moving member, and the left and right moving members are installed therein; And a blower lower housing coupled to a lower end of the upper housing to form a mixture discharge port between the upper housing and a lower surface of the blower having a motor installed therein for rotating the impeller.

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