JPS5855292Y2 - Combustible waste gas combustion furnace - Google Patents

Description

[Detailed description of the invention] The present invention belongs to the field of combustion equipment, and more specifically, to meet the requirements of the surrounding area, it is possible to use a vertical combustion system for burning combustible waste gas in a soundproof and non-flashing manner. Concerning a burning furnace.

It further relates to the field of combustion devices which are open and exposed to flowing wind streams.

In this field of equipment, it is necessary to provide protection against the effects of wind so that the combustion is not significantly affected by the pressurization and depressurization caused by the wind flow over the furnace.

In known vertically oriented furnaces with burners on the sides of the furnace, a windshield must be provided to prevent wind forces from reaching the burners directly.

Although such windshields do not exert direct wind power on the burner, they have the disadvantage that they can be significant depending on the amount of gas being combusted.

This disadvantage arises because the wind impact increases the pressure of the energy equivalent to V2/2 g of the wind on the upstream surface of the windshield, but essentially causes a pressure drop of the same amount on the downstream surface. .

The upstream pressure increase plus the downstream pressure decrease creates a turbulent flow of air inside the curtain or baffle, which disrupts the pressure on the various burners receiving combustion air from the space inside the windshield.

At low gas combustion rates, this effect causes the flame to be drawn from the burner into the interior space of the draft shield, where it causes significant heat loss to the furnace structure.

Therefore, it is important to design the windshield so that a uniform air pressure substantially equal to atmospheric pressure is available at the air inlet to uniformly supply air to the combustion flame.

The invention is a vertical combustion device for burning waste gases in a soundproof manner having a vertically oriented cylindrical furnace with a bottom hebburner located above the reference plane by a predetermined distance.

The inlet air opening at the bottom of the furnace has a cross-sectional area that is less than a selected fraction of the cross-sectional area of the combustion zone.

A cylindrical windshield surrounding the bottom of the furnace restricts air access to the space below the inlet air opening at the bottom of the furnace, thereby appropriately interrupting the flow of air from the inlet air opening. .

Because of this restricted neighborhood, the cross-sectional area for air flow is at least equal to the selected fractional area of the furnace.

This is the inlet air opening. Proper decoupling of airflow energy from the inlet air opening requires that the restricted proximity area be no greater than 2.5 times the air inlet area.

The inlet air opening is desirably no more than 85% of the furnace area.

One or more burners are provided in a suitable manifold so that the flame resulting from combustion of the waste gas is preferably blown into the furnace at an inlet air opening.

This inlet air opening area is preferably 0.2 to 0.2 to the cross-sectional area of the furnace.
It is in the range of 0.85 times.

The main object of the invention is to provide a furnace structure with suitable draft shield means, thereby providing a uniform pressure condition at the entrance to the furnace within the shielding of the draft shield.

By using a vertically oriented cylindrical furnace of cross-sectional area A, this and other objects are achieved and the limitations of the prior art are overcome in the present invention.

The cross-sectional shape can be circular or polygonal. The height of the furnace is at least equal to, and preferably greater than, the diameter of the furnace.

The furnace walls can be made of metal plates and are preferably lined with a refractory material to protect the metal plates.

The lower end of the furnace is partially closed with an annular plate.

The inner diameter of the annular plate has a burner in the opening of the annular plate, and where B is the cross-sectional area for air movement into the combustion zone in the furnace, B is 0.2 to 0.2 of the area A. It is in the range of 85 times.

Furnaces are supported on columns and the bottom of such furnaces is a predetermined distance above the reference plane.

To prevent the lower end of the furnace from being in direct contact with the wind, a cylindrical wall, baffle, or windshield is provided, which is substantially coaxial with and integral with the furnace, and whose diameter is less than the furnace diameter. so that the cross-sectional area of the annular space between the baffle and the outer surface of the furnace is at least equal to 0.9 A and not greater than 2 A.

The baffle is preferably somewhat higher than the distance to the bottom of the furnace above the reference plane.

These and other objects and advantages of the present invention, as well as a better understanding of its principles and details, will become apparent from the following description taken in conjunction with the accompanying drawings.

Examples will be described below.

Referring to FIG. 1, a furnace is designated by the number 10.

Furnace 10 has a cylindrical structure 12 with a vertical axis, the inner diameter of which is designated by the number 26 and the cross-sectional area of which is designated by A.

The lower end of the cylindrical furnace structure is provided with a partial lid in the form of an annular plate 16 with a solid axial opening 18 of diameter 20, excluding the obstruction provided by the burner 28. The area of the opening 18 is indicated by B.

There is a desirable range for the ratio of areas A and B.

Furnace 10 has a predetermined length that is greater than inner diameter 26;
0 is a reference surface (grade 5 surface) as is well known.
) 40 by a predetermined distance 22 and supported by a plurality of legs 24 .

One or more manifolds 30, 32 having respective conduit inlets 34, 36 are provided for supplying combustible waste gas to the burners, indicated schematically by the number 28.

Burner 28 is supplied with combustible waste gas by upright member 54 such that burner 28 is substantially in the plane of pole 16 .

Thus, the inlet air rising through opening 18 according to arrow 52 and the combustible gas exiting the burner are in good agitated contact.

A cylindrical windshield or shield 42 is provided around the furnace, the bottom end of which is in close contact with a reference surface 40.

The height of the windshield curtain 42 is such that its upper end 44 has a certain length 4, for example.
6 protrudes from the bottom 16 of the furnace.

Combustion air is guided downwardly into the space 58 below the furnace via the annular section 56 between the outside of the furnace wall and the inside of the draft shield and then guided upwards through the opening 18 into the furnace.

At this time, the air mixes with the gas exiting the burner 28 to form a stirred mixture.

This mixture is not shown but is known to those skilled in the art.
ignited and maintained ignited by one or more pilot lights.

This agitated mixing of combustion gases and introduced air provides rapid and complete combustion.

Therefore, by the time the heated gases reach the top 14 of the furnace, almost complete combustion has occurred and the amount of toxic substances affecting the immediate surroundings of the furnace is minimized.

This combustion is preferably complete within the cylindrical walls of the furnace so that the gases exiting the top of the furnace do not emit flashes or lights.

Air movement from the space 58 below the furnace floor is due in principle to draft within the furnace due to the presence of heated gases inside the furnace relative to the cold atmosphere outside the furnace.

The inlet air rising upwardly in the space 58 encounters the gas ejected from the burner in the opening 18 at the bottom of the furnace, and the combustion thus produced advances into the interior of the furnace.

However, when a small amount of gas is combusted, no heat is generated inside the furnace that would create a draft or stack effect.

Therefore, the draft at that time is very small and is normally 0.
0.03" WC or approximately 0.76:2 mm water column.

If the bottom of the furnace is not protected by a draft screen, the wind blowing under the furnace will create a suction effect on the opening 18.

This action causes the gas inside the furnace to flow backwards, drawing the flame from inside the furnace into the space 58, even if the wind speed is low, and as a result, the flame can damage the burner or the metal parts of the furnace structure.

If the draft of the furnace is 0.03'WC or approximately 0.762m
m water column and an unobstructed wind flow of 10 miles per hour or approximately 16.1 km per hour (14,66 ft/s or approximately 4.47 m/s) in the space between the furnace and the reference surface. , the low pressure exerted by the moving wind is -0,049'WC or about -1,24 mm water column, and the combustion gases are sucked downward into the space below the opening 18 and out of the furnace. There will be.

20 miles per hour or approximately 32.2 km per hour (29,
33 ft/sec or about 8.92 m/sec) wind is -0,19
This produces a low pressure of 8" WC or approximately -5,Q2 mm water column.

This value is greater than the draft effect caused by burning a significantly increased amount of gas, causing the flame to move toward the space below the furnace and cause significant thermal damage in that vicinity.

This explains why, in the operation of vertically firing furnaces, it is extremely important to completely isolate the area near the upper inlet to the burner opening from any lateral air movement.

Air must be introduced into the space below the bottom of the furnace in order for the gas to burn satisfactorily when released from the burner.

That is, the movement of air from the space below the floor must in any case take place towards the interior of the furnace.

Furthermore, it is extremely important that the air moves at as high a velocity as possible in order to obtain satisfactory combustion.

The rate of air movement through the burner opening is proportional to the square root of the pressure drop.

Draft energy occurs in the direction of the furnace where a sudden movement of air is required, and since the pressure drop is the pressure difference between the space below the furnace and the inside of the furnace, it is clear that the low pressure caused by the wind creating an air flow in the space below the furnace. should be avoided.

In the present invention, air enters the space below the furnace through the annular portion 56 according to the flow direction arrow 50.

The air inflow direction is downward and at a point farthest from the burner opening 18.

The inlet velocity is adjusted in a downward direction to establish a stable pressure condition of upward air flow in the vicinity of the upstream inlet to the burner opening 18 in which one or more burners 28 are located. be done.

Of course, a predetermined number of burners can be used depending on the amount of combustible gas to be burned.

The shape of the burners, their spacing, etc. are outside the scope of the present invention, and burners and manifolds of known shapes are sufficient.

Importantly, the burner is positioned within the opening 18 so that the air and gases have a large area of space below the burner and a large area of air velocity relative to the large area of space inside the furnace above the burner. The point of maximum is to be encountered within the reduced area B of the inlet opening.

As an optimum condition, the area B of the air opening 18, ie the free air space between the burners within the opening 18 defined as the so-called area B, should not be more than 0.85 times the area A of the furnace.

A ratio of B/A of the order of 0.2 provides the lowest area B to be provided.

A desirable value is in the range of 0.5 to 0.75 times the area A.

One reason for making area B smaller than area A is to obtain a higher airflow velocity within the gas ejection area from the burner in order to obtain maximum agitation.

Another reason is that the radial distance 6 of the opening 18 in the bottom annular plate 16 is
0 so that the position of the combustion gases in the opening 18 is displaced as much as possible from the annular space 56 in which the movement of the inlet air resides.

This specification was created for several reasons.

One reason is to ensure that distance 60 sufficiently separates the outer edge of inlet air opening 18 from the rate of air inflow into space 58.

Another reason is that in order to obtain proper operation when the gas flow for combustion is small or large, since the air flows through the burner openings 18 at a velocity according to the square root of the difference between the furnace down pressure and the inside furnace pressure. The reason is that a pressure difference is required.

If area B is equal to area A, the pressure difference will be very small, for example 0.10" WC or about 2.54 mm of water column,
If area B is 0.85 times area A, the pressure difference is 0.
, 10” WC or approximately 2.54mm water column to 0,138
``It rises to WC, which is about 3.5 mm of water column.

This increase in pressure drop increases the airflow velocity by as much as 17.6%, resulting in better combustion of the gas.

However, this speed increase is the least acceptable.

If area B is 50% of area A, the speed increase is 100%
Let's become.

Previously, it has been stated that maximum airflow velocity has important significance in satisfactory combustion.

This is important because air flow velocity is the source of agitation.

The completeness of combustion and the rate of combustion are directly proportional to the agitation, and this agitation is proportional to the air velocity.

The area of the annular space 56 is at least equal to the area B as described above.

The area of this portion 56 is defined by the space from the outside of the furnace to the windshield.

The downward flow of air, indicated by arrow 50, is important because of the uniform pressure in the space below the furnace, and if the area of section 56 is more than 2.5 times area B, this downward flow cannot be maintained.

In other words, the area of portion 56 is at least equal to area B or less than 2.5 times it.

Area B or the total cross-sectional area provided by one or more burner openings.

In all cases, however, distance 60 lies at the burner opening plane closest to the airflow, such as arrow 50.

Generally, the minimum value of the distance 60 is approximately 0.04 times the inner diameter 26 plus the thickness of the refractory material of the furnace wall above the annular plate 16.

Since the furnace is described as cylindrical with a vertical axis, the cross section can be circular or of any desired polygonal shape.

Similarly, the windshield or baffle may be correspondingly circular or polygonal.

In this way, the present invention uses screen 4 to prevent illuminance pollution.
2 completely shields the combustion area from the outside, so that no flash of light from this area leaks to the outside.

Also, in the present invention, the screen or windshield 42 completely surrounds the entire lower portion of the furnace.

Therefore, the air flow outside the windshield of the lower part (legs) of the furnace does not directly affect the direction of combustion air and combustion flame within the furnace.

That is, the air temporarily stagnates inside the windshield, regardless of the air velocity outside the windshield, and is then constantly supplied only from the bottom to the top of the furnace.

Therefore, backflow of gas inside the furnace is completely prevented.

The engineering design has dimensions to generate higher airflow velocities within the gas ejection area and to displace the combustion gases with as much air as possible.

Although the invention has been described with some particularity, it will be obvious that many changes may be made in construction details and arrangement of elements.

The present invention is not limited to the specific embodiments illustrated herein by way of illustration, but only by the claims appended hereto and their equivalents.

The embodiment will be described below.

(1) A vertically fired furnace for burning combustible waste gas, which (a) has an internal cross-sectional area of A, the axis is vertically supported, and the bottom supports the furnace; (b) a plate having at least one opening for the introduction of air and fuel and partially sealing off the bottom of the furnace; , (C) a burner positioned within said at least one opening having a net cross-sectional area B in the plane of the iron plate for the passage of air, and (d) coaxial with the bottom of the furnace. partially enclosing the space between the bottom of the furnace and the reference surface on which it is supported, the area of the remaining opening for supplying combustion air to the burners is C and at least a predetermined distance from the burners. A combustible waste gas combustion furnace comprising: a cylindrical windshield curtain positioned a distance apart; and (e) a member for supplying flammable gas to a burner.

(2) In (1) above, the windshield curtain has a cylindrical shape with a diameter larger than the diameter of the furnace, and the metal wall is cut from a polygonal metal wall, and the metal wall is on the reference plane and extends above the bottom of the furnace. , a combustion furnace providing an annular air opening of area C.

(3) In (1) above, area B is 0.85 of area A
Combustion furnace that is less than double.

(4) In (1) above, area B is 0.2 to area A
Combustion furnace in the range of 0185 times.

(5) In (1) above, area B is 0.5 to area A
Combustion furnace in the range of 0°75 times.

(6) In (1) above, area C is 1,0 to 1,0 of area B.
Combustion furnace in the range of 2°5 times.

(7) The combustion furnace according to (1) above, which has a heat-resistant lining material on the inner surface of the furnace and the inner surface of the plate.

(8) In (1) above, the minimum dimension from the outer surface of the furnace to the edge closest to area B is D is the inner diameter of the furnace, T is area B
A combustion furnace where the thickness of the heat-resistant coating inside the upper furnace is equal to (0,04D+T).

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the furnace and windshield, and FIG. 2 is a lateral sectional view taken along line 2--2 in FIG. Explanation of symbols 10: Furnace, 12: Cylindrical structure, 16: Annular plate, 18: Opening, 26: Inner diameter, 28: Burner, 40:
Reference plane, 42: Windshield curtain, 44: Upper end, 56: Annular part,
58: Space, 60: Radial distance.

Claims (1)

[Claims for Utility Model Registration] A vertically fired furnace for burning combustible waste gas, which (a) has an internal cross-sectional area of A, the axis is vertically supported, and the bottom part (b) a horizontal plate having a central opening and partially sealing off the bottom of the furnace; , the net cross-sectional area B of the air passage openings is 0.25 to 0.85 times the area A, and the smallest dimension from the outer surface of the furnace to the nearest edge of the area B is such that D is the area of the furnace. (C) the horizontal plate has an inner diameter equal to (0,04XD+T), where T is the thickness of the refractory material coating on the inside of the furnace above area B; (d) a burner installed at a position that does not protrude above or below the surface, and (d) having a diameter larger than the diameter of the furnace and extending from the reference surface to above the bottom of the furnace, and 1.0 to 2 of the area B. .5 times the area of the annular air opening, C, so that, due to the position of the burner relative to said opening and its dimensions, the combustion action is silent and cannot be seen by persons on the ground; A combustible waste gas combustion furnace comprising: a cylindrical windshield; and (e) means for supplying flammable gas to a burner.