JPS5889939A - Production of fused phosphate fertilizer - Google Patents

Abstract

PURPOSE:To produce fused phosphate fertilizer in large amts. with good thermal efficiency with installations of a small floor area by constructing two combustion furnaces at the top and bottom in a perpendicular cylinder, and using optionally fuels such as fuel oil and coal. CONSTITUTION:The effective volume ratio of a primary combustion furnace 1 of a perpendicular cylindrical shape and a secondary combustion furnace 9 connected to the lower part thereof by means of a throat 8, and set the effective volium ratio of the furnaces in a 1:0.7-1:7 range. In order to keep the heat radiation from the furnace 1 at <=10% the quantity of supplied heat, the product of fire furnace load and the cylindrical bore of the primary combustion furnace is set at >=1.32X10<6>. In operation, the temp. in the furnace is risen, then fuel is fed in the furnace together with primary air flow. When the temp. higher than the operation temp. is attained, raw material compsns. are mixed with secondary air flow and are fed into the furnace. The raw material compsn. and the fuel form vigorous swirling flow according to the prescribed air flow. The melt and combustion gases descend into the furnace 9 in parallel flow. After a short time of stagnation, the melt is removed, is cooled quickly and is crushed with water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fused phosphorus fertilizer using a cyclone combustion furnace. ! In other words, the purpose is to use gas, fuel oil, or Ishigankyo fuel as appropriate to produce smelted phosphorous fertilizer with high thermal efficiency, in large quantities, and with compact equipment with a small installation area.

Melted phosphorous fertilizers include phosphoric acid, magnesia, lime, silicic acid, and Kodo l! It is a fertilizer with a glass structure that contains elements, and its behavior in the soil is unique, and it exhibits excellent phosphoric acid O fertilizer effects not only on general soil fish, but also on volcanic ash souvenirs that have a high phosphoric acid absorption coefficient. It is well known that it is highly effective as a vehicle-improving agent and has contributed to food production not only in Japan but in many parts of the world.
It is common.

Molten phosphorus is produced in an electric furnace, open hearth, or blast furnace.For example, in the case of electric furnaces, the amount of impurities such as bound water and carbonates in the IIA material varies, but it is generally ,900k
Wh ~1000kWh@gc) I folded the electricity and got my l for $! At present, we rely on importing a considerable portion of our energy resources from overseas, and the costs have increased significantly.Nowadays, electric furnace electricity and open hearth fuel oil are indispensable! We will develop a melting furnace that can freely switch to various fuels, including coal and natural gas, and has good comprehensive thermal efficiency. Numerous devices have been devised outside of hearths and open hearths.

However, the melt of fused phosphorus fertilizer exhibits severe corrosivity to all commercially available refractories other than carbon, although there are some differences in degree.
No. 4, special public Akida! --? ? fj issue, Japanese Patent Application Publication No. 1973-11zt
In order to protect the fire resistance of the open hearth, No. tt adopts methods to avoid direct contact between the melt and refractories by self-coating with a raw material layer or preventing raw material dust from flying up inside the furnace. There is. Although various efforts were made to develop other ideas, they were not put to practical use in Japan other than the above-mentioned open hearth furnace and Carbon Lyung electric furnace. It is surmised that the main reason for this was the difficulty of refractories. In addition to electric furnaces, open hearth furnaces are commonly used to produce smelted phosphorous fertilizer. When pulverized coal is used as a fuel, although the pulverized coal and air are sufficiently mixed inside the burner, this is simply air transport, and most of the oxygen for combustion comes from the coal gas or air that evaporates from the particle surface. - Reliance on diffusion through a layer of carbon oxide takes time to burn, and requires a large-capacity furnace commensurate with the considerable residence time, which has the disadvantage of increasing both capital investment and area.

The invention of a rotating melting furnace is described in No. 1147 of the National Institute of Technology, and it was devised to cover the furnace wall with semi-molten material to protect the refractories. Maintaining the furnace wall below the critical corrosion temperature of the refractory is the ninth most effective JatLM means for maintaining the refractory, but there is no specific disclosure regarding heat baths, delicate temperature control, etc.

Japanese Patent Publication No. 118J Kokukuko No. 6 describes a melting method using swirling flow, and also describes the production of melted phosphorus using a cyclone combustion furnace of the Japan Society of Mechanical Engineers #6. The purpose of the former is to utilize low-grade rock, while the latter uses a part of the heat in the boiler's wet combustion furnace to produce smelted phosphorus fertilizer, and the heat of the furnace body and combustion exhaust gas are all consumed by the boiler. It is explained using the idea that leads to the evaporation system. In the former case, according to the example, -the ratio of phosphoric acid dissolved in citric acid to the total amount of phosphoric acid (
<return rate) is t O. 4%, and the latter has a solubility rate of up to 60%. The dissolution rate of melted phosphorus fertilizers currently manufactured and sold in Japan is almost 100% regardless of the type of fertilization.The reason for the low dissolution rate of the two mentioned above is that It is presumed that this was because the residence time in the furnace was extremely short, and sufficient melting reaction time was not secured.

Despite the early proposals for cyclone combustion furnaces, the problems of feeding a large amount of melted raw materials and fuel into a narrow combustion chamber, and the problems associated with production, were difficult to put into practical use. In order to achieve good performance, several uniform issues such as melting conditions to obtain a good melting rate, retention of W! melting state, and a good furnace structure to achieve these are necessary. , these issues have never been fully elucidated or solved.

The present inventor, Seihiro, has conducted extensive research to solve the above-mentioned problems regarding the method for producing molten phosphorous fertilizer using a four-cylinder combustion furnace, and has discovered equipment and operating methods that make it possible to produce molten phosphorous fertilizer. This completes the present invention.

That is, the present invention uses a vertical cylindrical primary combustion furnace and a secondary combustion furnace connected to the lower part thereof by a throat to melt a molten phosphorus fertilizer raw material composition to produce molten phosphorus fertilizer. The raw material composition and fuel are fed into a cyclone combustion furnace with an effective volume ratio in the range of 1:0.1 to lnia, and the scissors composition is heated and melted so that the product of the furnace load and the cylinder inner diameter is tJ2X10" or more, This is a method for producing melted phosphorus fertilizer, which is characterized in that a flow of melt and combustion gas 1f is guided to a lower primary combustion furnace.

The raw material composition of the molten phosphorus fertilizer is composed of peridotite, silica, and ferronickel, depending on the amount of mineral ore and serpentine, or silica, or ferronickel, according to the requirements. mold ji
Substances containing manganese, boronic, etc. are used as elemental components, and the fuel source can be appropriately selected depending on the necessary resources, such as heavy oil, 00M1 coal, and natural gas.

This is a method of producing molten phosphorus by melting it in a cyclone combustion furnace, but in order to take out the multi-liter molten liquid without trouble, according to the research of the present inventors, a horizontal cyclone combustion furnace is used. The melt flowing down from the primary combustion furnace is held for a short time in the melt retention layer at the bottom of the primary combustion furnace, which is connected to the bottom of the furnace by a throat. In order to maintain the retention layer at a temperature higher than the operating temperature at all times, it is necessary to eject the combustion gas from the primary combustion furnace downward in parallel flow with the melt to heat the primary combustion furnace. The raw material composition and fuel are fed through the primary combustion furnace inlet by a twin air stream so as to be placed in the same swirling flow, but the raw material composition and coal particles are struck against the furnace wall by centrifugal force. and captured in the melt layer. Heavy oil and coal powder have a small amount of primary air, and the raw material composition has a small amount of primary air, each converted to at least 10℃, 10 yen.
It is desirable to blow into the primary combustion furnace at a wind speed of ec or higher. If this wind speed is maintained, proper combustion will be maintained and no blockage of the inlet will occur.

The present invention will be described below with reference to the drawings.

FIG. 7 shows a manufacturing process diagram centered on a schematic cross-sectional view of a cyclone combustion furnace. Side wall iron skin/
Penetrate from a to the inside to connect the fuel inlet J and the fuel inlet J.
Nine, nine and 17I! It has a horse-tube structure, and the refractory lining/1) has a cooling water inlet and
And exit! To be water-cooled with a jacket (b) + V
It's C. Especially when using the air cooling method, a jacket! This diagram shows an example of a water-cooled system. In the soot, the raw material inlet λ and the fuel inlet J are
On the side wall iron skin/IL, one each is provided so as to face the tangential direction to the inner circumference of the horizontal cross section at the same position, but each
Alternatively, one or more raw material inlets and one or more fuel inlets may be provided at the 11C@wall position. The raw material inlet is also in phase with the fuel inlet J with respect to the swirling flow direction.

It is particularly preferable to delay the time by more than 10 minutes. This is very important, as the relationship between the ffi firing time of the fuel after being sent into the furnace and the timing of feeding the raw material is established, so that an effective swirling flow of the raw material, fuel and combustion gas is formed, and the combustion is good. Heat exchange is carried out with the film heat transfer resistance being sufficiently small, and effects such as being able to heat the raw material to temperature can be obtained.

The lower part of the primary combustion furnace l is connected to the primary combustion furnace D via a slow pipe. The secondary combustion furnace is the furnace wall/J'''
The furnace wall 0FP3 side is made of refractory bricks including some carbon bricks, and the outside is laminated with insulation bricks. The structure is such that a melting tank/I is formed at the bottom of the tap hole 10, and the inside of the furnace is equipped with an auxiliary burner 6b and a tertiary combustion air inlet, depending on the amount of heat and gas required. This is done so that the inside of the furnace is heated. The melt of dissolved phosphorus fertilizer is subjected to aMR from the I tube hole 10 and pulverized to form a product. On the other hand, the combustion exhaust gas is heat exchanged with the combustion air by the air preheater/J, passes through the raw material preheater/74, and the gas scrubber/74.
released from. Note that any heat exchanger can be used to recover heat from exhaust gas depending on the situation.

Next, to explain the structure and features of the cyclone combustion furnace used in the present invention, in relation to the trenched combustion furnaces, it is a vertical internal cylindrical primary combustion furnace! and throw at the bottom) f
Primary combustion furnace connected by! The effective volume ratio of i:
o, t~/: It is necessary to be in the range of ri. The reason for this is that within this range, the melt is mixed in the primary combustion gst melt for a limited period of time, and during this time it is heated by the combustion gas and can be tapped. , if l:0. If the irrigating time of the molten liquid is less than 100%, the product will vary widely), and in some cases, it will not be possible to obtain molten phosphorus fertilizer with a high releasability, and combustion will be poor or insufficient. On the other hand, if the temperature exceeds 1, the amount of heat dissipated by the primary combustion tsF becomes large9, and it becomes difficult to maintain the temperature above the operating temperature, making the tap cold, and heat recovery from the exhaust gas becomes inefficient. This is because the heat can be reduced by effectively producing melted phosphorous fertilizer.

The volume of the cylindrical part excluding the volumes of the throat-shaped part and the throat t is the volume of the secondary combustion furnace from the exit horizontal line of the throat t to the slag line of the tap hole IO.

In addition, in the seventh combustion furnace l, it is preferable that the ratio of the drawing diameter to the cylinder inner diameter and the length of the cylindrical part is within the range of Pa/~/:Da in order to ensure smooth combustion and melting and retention of raw materials in the furnace. .

Further, let fH be the ratio of the height from the vertical cylinder full length to the lowest fuel inlet port to the vertical cylinder full length, and let R be the ratio of the throat opening diameter to the cylinder inner diameter. It is also related to the position of the fuel inlet J. When the aperture ratio R is close to l, stable combustion and proper melting cannot be achieved when fuel is fed into the lower part of the dimple υ, while on the other hand, when R becomes smaller than 0.3p, there is a tendency for blockage. All of these pose a hindrance to stable operations. Because of this, the slow) tldB is set to be variable depending on the operating conditions, but this
When an empirical formula was obtained, it became clear that the following formula holds true.

H≧arich+O0thing3・R (In the formula, M and R represent the above meanings and /≧R≧0.3.) Therefore, the cyclone combustion furnace is designed so that the above relationship is S9. It is configured.

Next, from a thermal point of view, the primary combustion furnace is a self-coating system that maintains the operating temperature at g (/JIO ℃ 9), which allows the molten phosphorus to flow, and is air-cooled or water-cooled because it is subject to severe erosion by the melt. Layering〉High resistance-〇Erosion must be prevented.

Therefore, during operation, a slag solidified layer and a semi-molten layer and a molten liquid layer are formed on the furnace wall, and this slag layer has a self-side chain property of temperature, and when the temperature inside the furnace decreases, a slag solidified layer forms. As the thickness increases, the internal temperature rises by 11 degrees, and conversely, if the internal negative temperature rises too much, ai! The solid layer is eroded and becomes thinner, and the amount of heat transferred from the furnace wall to the outside increases and becomes thinner. Therefore, for example, if a sludge phosphorus fertilizer manufacturing plant coexists with other production equipment that uses steam, the KitFii can be cooled with water, and at the same time the combustion furnace waste can be put into a waste heat boiler to produce steam and sludge phosphorus. can be advantageously co-produced. In addition, in the case of a dedicated smelting phosphorus fertilizer factory that does not require steam, it is advantageous to cool the furnace walls with air and recover it as hot air for use in drying raw materials and products, preheating combustion air, etc. be. At this time, it is necessary to use a refractory for the furnace wall that has good heat conduction), especially 3.
Average heat conduction direct kcal/from 00℃ to 1900℃
A refractory having a temperature of m-h·°C or higher, for example, a material made of carbon or silicon carbide is desirable. In this case, if the primary combustion furnace is operated at an air ratio of less than 60, burnout of the carbonaceous refractory can be avoided and a self-coating layer can be formed despite the fact that it is a combustion melting furnace. On the other hand, the heat load on the primary combustion furnace during operation is simply the amount of heat required to melt the melted phosphorus fertilizer raw material,
The supply of temperature is not only important, but also important in terms of heat balance and reducing heat dissipation from the primary combustion furnace. Inner diameter 0.
In the example of the test furnace of も#m, in order to reduce the heat radiation from the air-cooled seventh combustion furnace to about 10 or less of the supplied heat amount, JX10'
A furnace load of kcal/h or more is essential (To), and as the heat load decreases, the heat radiation rate from the seventh combustion furnace increases relatively. This is due to an increase in the heat load, which increases the feed rate of raw materials, increases the amount of melt flowing down the furnace wall per unit time, and the thickness of the melt layer increases, resulting in the amount of heat transferred toward the furnace wall. One of the major reasons is to reduce the If the diameter of the primary combustion furnace increases, the surface area of the volumetric furnace 9 will relatively decrease, and the furnace load limit will also change. In general, the relationship between the furnace load and [vk is limited, and within nine ranges, the relationship is expressed by the following equation.

qD In the proverb, q Furnace load (kaaj/Otori 1・h) D/Diameter of the secondary combustion furnace (K) Constant diameter 0.
If /11'·h is used as a reference, qD■83 becomes X10·. Using this indigo, find the limit qO value for each diameter, that is, the product of the furnace load and the inner diameter of the primary combustion furnace cylinder.
If the value is 0" or more, the heat radiation from the primary combustion furnace wall will be approximately 10".
% or less.

The method for producing melted phosphorous fertilizer according to the present invention has been explained above according to Fig. 1. However, unlike the water-cooled cyclone combustion furnace shown in Fig. 1, Fig. In the figure, No. JvA represents a horizontal cross-sectional view thereof. This cyclone combustion furnace has a rounded throat t that adjusts the flow of gas and particles in the primary combustion furnace, and an upwardly bent part l&, which allows the combustion gas and melt to flow respectively through the throat f and its bypass port lb. As shown in FIG. 3, the fuel inlet J is 90 degrees out of phase with respect to the fuel inlet J so that the fuel can flow down into the secondary combustion furnace. Historically l541L
The figure shows an example in which in the above-mentioned cyclone combustion furnace, one inlet is provided at multiple positions on the side walls of raw material inlets Co1, Cob and fuel inlets J&, 3b with a phase difference of 000, JIIJ It shows a cross-sectional view similar to the figure.

As described above, it will be understood that in the present invention, those having various dead-type structures that satisfy the above conditions can be appropriately selected. When operating a cyclone combustion furnace such as the one shown in Fig. 9 and #i No. 41E above, additional teeth may not be necessary in a small-capacity furnace where the bypass port zb is likely to be clogged with dust.

Thus, in the present invention, when operating, the start-up gas or oil burner and optionally the auxiliary burner are fired to raise the temperature inside the furnace, and then the fuel is introduced together with the primary air flow. Once above the operating temperature, the feed composition is mixed with the primary air stream and blown into the furnace.

In steady state, the raw material composition and fuel form a violent swirling flow according to the air flow with a predetermined air ratio, and the melt and combustion gases descend in parallel flow into the primary combustion furnace. The melt is confined to the secondary combustion furnace, where it remains for an fc assembly period, and then taken out through a tap hole, where it is quenched and pulverized at a water pressure of approximately Skg/cys. This is dried by a conventional method and then pulverized as necessary. The products are made by crushing and classifying the melodies.On the other hand, the combustion exhaust gas is finally released after being cleaned as explained above.Unlike in the case of siphon combustion furnaces for boilers, Nox is also kept below regulatory standards in this process. In addition, heat recovery from exhaust gas can be applied in combination with conventional mining techniques, and high thermal efficiency is expected.

Example 1 In the apparatus shown in FIG. 1, H-0,14, RmOJO.

The effective volume ratio of the primary combustion furnace and the primary combustion furnace is 6,
Cooling water was passed through the jacket of the primary combustion furnace, the preheating gas burner 6a was ignited, and the temperature inside the furnace was gradually raised. After about 3 hours, the temperature inside the primary combustion furnace was measured with a radiant high temperature needle and reached 71
At this point when the temperature reaches 00℃, gradually start feeding powder (4JOIka*1 kg) from the fuel supply port J on the primary air flow, and open the KJI fuel supply port so that the air ratio becomes 804. Start sending only air from C to C. 7 state - 1 inside the furnace
At 4110℃ and Natsutomo, stop the gas burner,
A powder mixture of serpentine rock and phosphate rock is gradually introduced from the raw material supply port using secondary air tltWc. The feeding lid was increased and finally powdered coal IIi wet weight was 1111b, Florida phosphate rock powder Koku 7h, and Ja-Ilwa powder 14 san to 47
(These two raw materials were crushed and mixed in advance and then supplied to the preheating device.) On the inner surface of the seventh combustion furnace, a solid layer is formed in which the refractory lining and melted phosphorous fertilize are combined, and the melt remains in one state at the bottom of the tsF, and the lower part solidifies. Let the molten liquid flow out through the tap hole 10, and quench it by a water stream from a nozzle with a water pressure of 1 kg/ad in the usual manner, and crush it with water. The production rate of dissolved phosphorus fertilizer in the product was reached at DiOX Pass/h. The composition of the nine molten phosphorous fertilizers obtained is as follows.

Total amount of phosphoric acid (as PmOs) -〇, 16㎅〈Soluble phosphoric acid (as 'tOs) -〇, tO* solubility rate
tt, ri/S With the above operations, the preheating temperature of the raw material is 200°0. The preheating temperature of the secondary air is 4Ioo'
0. Furnace load of i-state kiln j X / 0” kcal
/ml -h furnace load and! State #k(θ, #
The product of (darn) is ^λ x 701. Temperature of molten phosphorus molten liquid coming out of the primary combustion furnace/J! Heat dissipation from the 0"Ol state furnace was 3% of the heat supply.

The air ratio was adjusted to 804 based on the oxygen concentration of the exhaust gas. The overall thermal efficiency was 81%.

Example Using the same equipment as in Example 1, the throat t.

The operation was carried out under the same operating conditions as in Example 1, except that the 7th flange of the section was removed, a water-cooled, refractory 2-inning insulator was inserted, and the opening ratio tm of the speed was varied, and the situation was observed. did. The result is as follows.

Example J The flange of the throat part of the same device as in Example 1 was removed, a 9-ton water cooling plate was inserted, and the throat opening ratio Rt was varied within the range of the present invention, and at the same time, Height of fuel inlet II f: 0. The Qiao Zhiba cylinder part was replaced at points 9 to 0 and tt, and the operation was carried out under the same operating conditions as in Example 1 except for point 9. The results are as follows.

(Note) Lower limit value of H obtained by substituting R into the following formula
HO, Koku 10, Da JR

[Brief explanation of drawings]

Fig. 1 is a manufacturing process diagram centered on a schematic cross-sectional view of a cyclone combustion furnace showing an embodiment of the present invention, the striped lambda diagram and the reference figure are cross-sectional views showing an example of a cyclone combustion furnace, and Fig. 3 is Figure 3 represents their horizontal cross-section. Moreover, FIG. 5 is a graph showing the relationship between the lower limit of the furnace load of the seventh combustion furnace and the same inner diameter in order to keep the heat radiation from the primary combustion furnace below 1016. l...Primary combustion furnace, /&...@Wall shell, /b...Refractory 2 innings, Ja%Co, Cob...Raw material inlet, J
IL, J, Jb...fuel inlet, da...jacket, ja...cooling water inlet, rb...cooling water outlet, 6&...
・Gas or oil burner for start I knob, 4b... Auxiliary burner, ri... Tertiary air inlet, ta... Bent part of throat, 111. Throat, jtl... Bypass port of throat, de...・Co-order combustion furnace, 1o--tap hole, ll... melt retention layer, lj... co-order combustion furnace furnace wall,
is...air preheater, llI...raw material preheating record, lj...
Raw material hopper, 14... dust collector, l... exhaust gas cleaning machine, l... fuel storage tank. 231- 3 groups II 圀Manufacturing method 3, relationship with the case of the person making the amendment Name of patent applicant (Ishiita Makoto-4, Director of the Agency of Industrial Science and Technology, Agent)
(of Nippon Chemical Industry Co., Ltd.) b, Renewed representative (of the Director of the Agency of Industrial Science and Technology) 7. Subject of amendment (1) Application (11) Ill details (8) Power of attorney 8. Contents of amendment (1) Engraving of application Submit as attached. (No change in content) (11) Submit an engraving of the specification as attached. (No change in content) (8) Submit the letter of appointment as attached.

Claims (1)

[Claims] (1) A cyclone combustion furnace is used to heat the molten phosphorus fertilizer raw material composition to produce molten phosphorus fertilizer.The cyclone combustion furnace is connected to the primary combustion furnace and its lower part by a soot. The effective internal volume ratio with the ninth combustion furnace is 1:0. γ~l: Rinohan 1
By feeding the cyclone combustion furnace KOJI family composition and fuel into lIl, the product of the furnace load and the cylinder inner diameter is
A method for producing smelted phosphorus fertilizer, which comprises heating the iron composition as described above, and guiding the molten material and combustion gas in parallel flow to the primary combustion furnace at the lower part. (jal / For the secondary combustion furnace, the height ratio from the bottom of the vertical cylinder to the lowest fuel inlet with respect to the straight cylindrical metal height and the ratio ratio of the throat opening diameter to the cylinder inner diameter are expressed by the following formula % formula %) A method for producing melted phosphorous fertilizer according to item 1 of the claims. (3+ / The secondary combustion furnace has 1 - or multiple positions on its side wall, each facing in the tangential direction to the inner circumference of the horizontal section.
or several inlets for the fuel and melted phosphorus fertilizer raw material composition, and the raw material inlet and the fuel inlet are delayed in phase by about -00 degrees or more with respect to the swirling flow direction on the horizontal cross section. If you are there! A method for producing a melted phosphorous fertilizer according to claim 1 or 7, wherein the amount of i. ζ41 / JOO℃ of secondary combustion furnace turning wall constituent material ~ /44
It is characterized in that the average thermal conductivity at 00°C is greater than or equal to kcal/m-h·°C, and the furnace is operated at an air ratio of less than 0. The method for producing melted phosphorous fertilizer according to any one of items 1 to 3, where l:t* is the desired range.