JPS6349614A - Premixing atomizer - Google Patents

Abstract

PURPOSE:To improve making of fine particles and provide a stable flame having reinforced flame stabilization characteristic by a method wherein medium for making fine particles is arranged adjacent to a mixing chamber and a fuel separation nozzle is provided in order to connect at least one second mixing chamber formed with injection holes at a side facing to a furnace, a second mixing chamber and an inner diameter modified part of a fuel supplying portion. CONSTITUTION:Fuel 2 is pressurized by a fuel supplying nozzle 21 and a fuel separation chamber 25, a dehydration occurs at a fuel separation nozzle 30 having a small diameter and CWM having a more decreased condensation than that of initial CWM is supplied to a gas-liquid mixing chamber 28. In turn, CWM having more condensed condensation than that of the initial CWM is supplied from a fuel nozzle 26 to the gas-liquid mixing chamber 27. CWM having low condensation is made such that its rheology characteristic is varied from it dilatant to Newtonian and is facilitated to be fine particled. In turn, a highly condensed CWM shows a variation from its dilatant to pseudo-plastic condition, resulting in that a remarkable superior fine particle formation can be made. Therefore, ignition is made stable and a flame stabilization characteristic is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a premix atomizer, and in particular, a premix atomizer suitable for achieving high efficiency and low pollution combustion of slurry fuel containing fine powder solids. Regarding.

[Conventional technology]

CWM (Highly Concentrated Coal/Water Slurry) is a fluidized fuel that can be sprayed and burned using an atomizer in the same way as conventional oil. The cause of the poor ignition performance is that heat is consumed in evaporating water, and the ignition distance is considerably longer than that of pulverized coal. In addition, although there are many unknown reasons for the increase in unburned coal, it is likely that the tiny coal particles are agglomerated within the droplets and are not burnt out as individual particles like pulverized coal. This is because moisture reduces combustion. Furthermore, a characteristic of coal combustion is that it has poor flame stability and is difficult to form a stable reduction zone when the flame is lifted.
It is difficult to suppress NOx (it may not reach high temperatures)
This fact also applies to pulverized coal combustion.

Therefore, in order to increase the combustion efficiency of CWM to the level of pulverized coal, it is necessary to develop an atomizer that has excellent spray performance and is suitable for CWM combustion.

FIGS. 6 and 7 are cross-sectional views showing two examples of the structure of a typical conventional two-fluid atomizer.

FIG. 6 shows an example of an internal mixing type. At the bottom of the atomizer chip main body l, which ejects CWM from the ejection hole 8, there is a fuel nozzle 4 for introducing the fuel 2, and a fine flow medium supply hole for introducing the atomization medium 3. 5 and gas-liquid collision holes 6 for mixing the fuel 2 and the atomizing medium 3, and an intermezzoate plate 10 for supplying the mixture to the mixing chamber 7 of the main body 1. On the other hand, main body 1 is cap naft 9
are integrally connected by.

In the configuration shown in FIG. 6, the fuel 2 and the atomization medium 3 are mixed together in the gas-liquid collision hole 6 opened at the center of the intermezzoate plate 10 to perform primary atomization, and then the mixture chamber 7
After being allowed to stay in the water, it is injected from the ejection hole 8 and atomized.

FIG. 7 shows an intermediate mixing type atomizer called a Y-jet type, which has a fuel supply hole 11, an atomizing medium hole 12 in the artificial part, and a mixing jet hole 1 connected to the fuel supply hole 11 in the middle part.
3, a burner gun inner cylinder 15 for supplying the introduced atomization medium 3 to the atomization medium hole 12, and a burner gun inner cylinder 15 that is arranged concentrically with respect to the inner cylinder 15 and introduced fuel. A burner gun outer cylinder 16 that supplies fuel 2 to the fuel supply hole 11, and gaskets 17a and 17b disposed on the contact surface between the upper end of the outer cylinder 16 and the main body 14, and the contact surface between the inner cylinder 15 and the main body 14, respectively. It is comprised of a cap nut 18 that integrally connects the main body 14 and the burner gun outer cylinder 16.

In the configuration shown in FIG. 7, each of the fuel 2 and the atomization medium 3 is individually supplied to the atomizer chip body 14 via a burner gun, and the two are collided and merged within the mixing ejection hole 13 in this body 14, and the mixture is The liquid is directly injected from the mixing jet hole 13.

Both of the atomizers shown in Figures 6 and 7 have been used extensively in oil-fired boilers for commercial and industrial use.However, when the fuel is CWM, a large amount of relatively large droplets are generated. It is insufficient in terms of atomization, and it is extremely difficult to apply it as is.

On the other hand, in CWM, even if the apparent viscosity, concentration, or coal particle size distribution is the same, if the rheological properties differ, the atomization properties will vary greatly. This feature is observed in any type of atomizer mentioned above. Compared to pseudoplastic or Newtonian CWM, CWM exhibiting giratant properties has an increased viscosity with respect to an increase in shear force, resulting in poor atomization. Depending on the type of coal, manufactured CWM often exhibits giratant properties.

Even if the CWM used exhibits gilactonity, it would be extremely advantageous if, by selecting the structure of the atomizer, at least the same level of atomization properties as other CWMs with rheological properties could be obtained.

Regarding this type of device, see Proceedings of the Japan Society of Mechanical Engineers No. 865-1 (August 1986), p. 109, Mitsubishi Heavy Industries Branch Axis Vol. 1.22. No. 5 (1985-9>66
Page 4, Ishikawajima Harima Heavy Industries Branch Axis Vol. 25. No,
5 (1985-9) 308.

[Problem that the invention seeks to solve]

However, when conventional atomizers are applied to CWM, sufficient atomization cannot be achieved, resulting in extremely unstable ignition and flame stability, resulting in increased emissions of not only unburned matter but also NOx. Additionally, there is a lot of unburned remains at the furnace outlet, which poses a problem in ash disposal.

On the other hand, if the type of coal changes, not only the apparent viscosity but also the rheological properties of the manufactured CWM will change significantly. Although rheological properties have many effects on atomization properties, conventional techniques have not taken measures to deal with such wide changes in physical properties of CWM.

The purpose of the present invention is to solve the problems of the prior art described above,
An object of the present invention is to provide a premixed atomizer capable of producing a stable flame with improved atomization and enhanced flame holding.

Means for Solving Problem C] In order to achieve the above object, the present invention provides a fuel supply section having a shape with different inner diameters on the upstream side of the mixing chamber, and adjacent to the mixing chamber, at least One second mixing chamber is provided, and the atomizing medium and fuel from the fuel supply section are supplied to this mixing chamber so that two types of CWM concentrations can be obtained.

[Effect]

The mixing chamber located in the center contains highly concentrated pseudoplastic CW.
The mixing chamber provided at the periphery generates neutron CWM with a reduced concentration, and atomization is promoted in both cases. The atomized stream sprayed from each mixing chamber has a small atomized particle size as a whole, improving ignition flame stability and reducing unburned matter.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 and FIG. 7142 are a sectional view and a plan view showing an embodiment of the present invention. Note that the same reference numbers are used for parts that are the same as in Figure 6.

The atomizer according to the present invention consists of an intermezzoate plate 19 into which the fuel 2 and atomization medium 3 are introduced, and an atomizer chip body 20 that is coupled to this plate 19 and injects CWM, both of which are connected to a cap nand 9. Fixed by

The intermezoate plate 19 is connected to a fuel supply nozzle 21, a fuel separation chamber 22 connected to the nozzle 21, and a surrounding area of the fuel separation chamber 22, into which the fuel 2 is introduced and is made of a wear-resistant material such as ceramics. A first atomization medium supply hole 23 is provided and into which the atomization medium 3 is introduced.
and a second atomizing medium supply hole 24.

The atomizer chip body 20 also includes a fuel separation chamber 25 communicating with the fuel separation chamber 22, a fuel nozzle 26 communicating with the fuel separation chamber 25, a first gas-liquid mixing chamber 27 communicating with the fuel nozzle 26, and a second gas-liquid mixing chamber 27 communicating with the fuel nozzle 26. Collision plate (target plate) 2 made of wear-resistant material provided on the inner periphery of the second gas-liquid mixing chamber 28 and the first gas-liquid mixing chamber 27 communicating with the atomization medium supply hole 24 of
9. A fuel separation nozzle 30 that communicates the fuel separation chamber 25 and the gas-liquid mixing chamber 28, an ejection hole 31 formed on the gas-liquid ejection surface of the gas-liquid mixing chamber 27, and an ejection hole 31 formed on the gas-liquid ejection surface of the gas-liquid mixing chamber 28. The ejection hole 32, the atomization medium supply hole 23, and the gas-liquid mixing chamber 27
each of the atomizing media nozzles 33 communicating with the bottom of the atomizing medium nozzle 33 .

The fuel separation chamber 22 is set to have a larger diameter than the fuel supply nozzle 21. Further, the atomizing medium supply holes 23 and 24 are formed alternately in the circumferential direction.

The central part of the downstream side of the fuel separation chamber 25 is
The hole diameter is reduced (fuel nozzle 26) in order to pressurize the fuel within. Furthermore, the total cross-sectional area of the fuel separation nozzles 30 is set to be smaller than the cross-sectional area of the fuel nozzles 26.

Next, the effects of the premixing atomizer configured as described above will be explained.

The fuel 2 flows through the inner cylinder of the burner gun and enters a fuel supply nozzle 21 that opens at the center of the intermezoate plate 19.
is supplied under pressure. Further, steam or compressed air, which is the atomizing medium 3, flows through the annular gap between the inner cylinder and the outer cylinder, and is supplied to the atomizing medium supply holes 23 and 24, each of which has a plurality of openings in the ink mezzoate plate 19.

The atomizing medium 3 supplied via the atomizing medium supply 23 and the fuel 2 supplied via the fuel nozzle 26 collide with the collision plate 29 and mix (primary atomization), and the mixture enters the mixing chamber. It is injected on 27th. The gas and liquid in the mixing chamber 27 is emitted as a spray stream through the plurality of ejection holes 31 .

On the other hand, the fuel branched from the fuel separation chamber 25 is mixed with the atomization medium 3 (steam) supplied from the atomization medium supply hole 24 in the gas-liquid mixing chamber 28 . The mixture generated in the gas-liquid mixing chamber 28 is ejected from each of the ejection holes 32, but its properties are different from those from the ejection holes 31.

Here, it is assumed that cwM exhibiting giratant properties is supplied to the atomizer as fuel.

The fuel fuel 12 is pressurized by the fuel supply nozzle 21 and the fuel separation chamber 25, and dehydration occurs in the fuel separation nozzle 30 with a small hole diameter, so that the fuel gas 12 is supplied to the gas-liquid mixing chamber 28 at a lower concentration than when it was initially supplied. At the same time, the apparent viscosity also decreases.'') CWM is supplied. On the other hand, from the fuel nozzle 26, CWM with a higher concentration than the original one is supplied to the gas-liquid mixing chamber 27. However, the apparent viscosity does not necessarily increase.

The rheological properties of CWM that has been reduced in concentration change from giratant (the property that the shear force increases as the shear rate increases) to Newtonian (the property that the shear rate and shear core force are in a proportional relationship), making it easier to atomize. Become. on the other hand,
Highly concentrated CWM changes from giratant to pseudoplastic (a property in which the core shear force decreases as the shear rate increases), resulting in significantly better atomization. This action is a feature of the present invention, and will be explained in detail below.

FIG. 3 shows a comparison of particle size distribution curves of atomized droplets from a conventional atomizer and an atomizer according to the present invention.The atomizer according to the present invention has more minute droplets and relatively fewer large droplets, i.e. , it can be seen that the atomization is good. In the atomizer according to the present invention, when comparing the particle size distribution at the center of the spray flow and at the outer periphery, it is found that C exhibits pseudoplasticity at high concentrations.
In the center of the spray flow where the WM is atomized, the amount of minute droplets is larger, but the number of large droplets is also relatively larger. These property changes are considered to be due to differences in CWM concentration and rheological properties.

FIG. 4 shows a schematic diagram of the flame structure under conditions using the atomizer of the present invention. In FIG. 4, 20 is the atomizer chip body, 32 is the burner throat, 33 is the combustion air, and 34 is the high temperature reduction. Flame 35 is an oxidizing flame.

As is clear from Figure 4, the flame center becomes a high-temperature reduction zone where the atomized spray of highly concentrated CWM burns, and low NOx combustion is achieved through downstream re-burning (Rs-burning). . In the past, there was concern that combustion would be delayed due to the lack of oxygen and temperature at the flame center, resulting in an increase in unburned matter, but in the case of the present invention, this handicap is overcome by improving atomization. is supplementing.

FIG. 5 shows experimental data organized in terms of the relationship between NOx and unburned matter, and demonstrates the effectiveness of the atomizer according to the present invention. When compared at the same unburned content level, the atomizer according to the present invention shows a 100 to 200 ppm reduction in NOx. Furthermore, when compared at the same -NOx level, the amount of unburned matter is significantly reduced, which shows that the effect of the atomizer according to the present invention is extremely large.

In addition, in the above configuration, the number of ejection holes 31, 32,
Although the hole diameters were made the same and the opening positions were set on the same burner radial axis, these conditions are not particularly specified in the present invention. By appropriately combining changes in the number, hole diameter, or opening position, it is possible to produce various effects accompanying the effects of the present invention.

Furthermore, the two-fluid atomizer according to the present invention is applicable not only to CWM, which is specifically taken as an example in this text, but also to other slurry fuels in which finely divided solids are suspended in the liquid.

The applicable fuels are listed below.

(1) COM (coal/oil slurry) (2) Methanol (coal/methanol slurry) (3) P
WM (Petroleum Coke/Water Slurry) (4) Pitch/Water Slurry (5) Solid Residue Carbon Inferior Residue with Many Bones According to the embodiments of the present invention described above, the effects as specifically listed below can be obtained.

(1) Atomization characteristics are improved for CWM of any nature, ignition is stabilized, and flame stability is improved.

(2) In connection with the above-mentioned improvement in flame stability, the combustion effect is improved because the unburned content in the fly ash is reduced.

(3) Related to effects (2) and (3) above, not only does the overall amount of sinter ash (cinders, unburned ash) supplemented by A/H and clinker ash that falls to the bottom of the furnace decrease, The unburned content in the ash is reduced. This greatly facilitates ash disposal and expands the scope of ash usage.

(4) Boiler furnace can be made smaller due to shorter flame. Therefore, it is advantageous from an economic point of view.

(5) The above-mentioned effects (1) to (3) are also advantageous for slurry fuels using high fuel ratio coal (fuel ratio - fixed carbon/volatile content), which has poor combustibility.

(6) Due to the effect of (1), a stable high-temperature reduction region is formed near the burner, and NOx can be reduced.

(7) Enables larger capacity (scale amplifier).

(8) The amount of atomization medium (steam) can be reduced. Therefore, boiler efficiency increases and auxiliary equipment power costs can be reduced.

(9) Low excess air combustion becomes possible. Therefore, low-temperature corrosion can be prevented even if a type of coal containing a large amount of S (sulfur) is used (although coal imported into Japan generally has less than 3 sulfur).

〔Effect of the invention〕

As described above, according to the present invention, since the atomization characteristics are improved, ignition is stabilized, flame stability is improved, and combustibility is significantly improved, thereby facilitating energy saving and environmental protection measures.

[Brief explanation of drawings]

Figures 1 and 2 are a cross-sectional view and a plan view showing an embodiment of the present invention, Figure 3 is an atomization characteristic diagram showing the particle size distribution of the spray,
Fig. 4 is a characteristic diagram showing the spray flow pattern in the present invention, Fig. 5 is a characteristic diagram of unburned content in ash showing the fuel vF and test results of the present invention and the conventional one, and Figs. 6 and 7 are the characteristic diagrams of the conventional It is sectional drawing which shows two examples of an atomizer. 19...Intermezoite plate, 20.
... Atomizer chip body, 21 ... Fuel supply nozzle, 22.25 ... Fuel separation chamber, 2
3.24... Atomization medium supply hole, 26...
...Fuel nozzle, 27°28... Gas-liquid mixing chamber,
29...Collision plate, 30...Fuel separation nozzle, 31.32...Ejection hole. Agent Patent Attorney Masaru Nishimoto - Figure 1 Figure 2 Figure 5 Otoo 200 300 40O NOx (026%tQ, ppm) Cumulative 11t8m (%) Toohe1 -

Claims (2)

[Claims] (1) In an atomizer equipped with a mixing chamber that mixes separately supplied fuel and atomization medium, and a jetting section that jets the mixed fluid in the mixing chamber to the outside, the atomizer has a shape that has a different inner diameter. a fuel supply section disposed on the upstream side of the mixing chamber; and at least one fuel supply section disposed adjacent to the mixing chamber, supplied with an atomizing medium, and having an ejection hole formed at an end on the furnace side. 1. A premixing type atomizer comprising: two mixing chambers; and a fuel separation nozzle connecting the second mixing chamber and the inner diameter changing section of the fuel supply section. (2) the mixing chamber is arranged on the central axis of the atomizer;
The premixing atomizer according to claim 1, wherein the second mixing chamber is arranged annularly at predetermined intervals around the mixing chamber.