JPH0361481B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for controlling the opening and closing of spray nozzles in a spray drying tower. Generally, in spray drying of powder or granular materials such as detergents, a raw material slurry is sprayed into a drying tower using a large number of nozzles, and the slurry is brought into contact with hot air to obtain dry particles. In such contact between gas and liquid in spray drying, it is preferable to uniformly disperse the slurry from the viewpoint of drying efficiency and uneven drying of the product.Actually, in a spray drying tower, a large amount of slurry is dispersed in a uniform spray pattern. In order to spray the drying material, a large number of nozzles are arranged at equal intervals along the inner circumference of the drying tower. However, in such a spray drying tower, although excellent uniformity can be obtained when all nozzles are opened, in actual equipment operation, it is difficult to use all the spray nozzles installed. In order to maintain the quality of dry particles such as moisture and bulk density, slurry feeding speed, hot air temperature for drying,
It is common to control the number of open spray nozzles as well as the spray pressure. Furthermore, depending on the properties of the slurry, the spray nozzle may become clogged during operation, and once such nozzle blockage occurs,
The spray pattern is greatly disrupted, causing variations in the moisture content and bulk density of the powder, making it difficult to obtain a product of stable quality, so it is necessary to open and close the nozzle to deal with this. Conventionally, as a method for uniformly spraying from a large number of spray nozzles arranged at equal intervals as described above, it has been said that it is preferable to open the nozzles symmetrically. On the other hand, when nozzle numbers 1, 2, ..., T are assigned sequentially in the circumferential direction and N of those spray nozzles are opened, the nozzle with nozzle number X calculated by the following formula is opened. I try to do that. X=INT(A・T/N) However, INT is a function that gives an integer value by rounding down the decimal places, and A is the nozzle opening order.
~N integers are assigned sequentially. According to this method, for example, when opening five nozzles using a drying tower in which eight nozzles are arranged at equal intervals, the open state shown in FIG. 1A (white circles indicate open nozzles) , black circles are closed nozzles), and although a completely symmetrical shape cannot be expected, Fig. 1 B and C
The symmetry is much better than other open configurations such as those shown in . However, for drying purposes, when increasing the number of open nozzles from the five open nozzles in FIG. 1A to six,
It will be necessary to open the nozzles 2 and 5 from the state shown in Figure 1A, and open the nozzles 3 and 3 that are currently in use.
The number nozzle will be closed. That is, in the above conventional method, as the number of open nozzles is increased or decreased, the number of nozzles that must be opened and closed is large in order to maintain approximate symmetry, the operation time becomes long, and the influence on quality cannot be ignored. The present invention is capable of opening and closing the spray nozzles in a spray drying tower equipped with a large number of spray nozzles in a short period of time without impairing the thermal efficiency or the uniformity of the spray. In addition, the spray pattern can be changed to a substantially uniform state in a short period of time, not only under normal conditions, but also when the nozzle becomes clogged, thereby producing products of stable quality. The purpose is to To achieve the above object, the nozzle opening/closing control method of the present invention arranges a large number of spray nozzles on a required number of spray stages at substantially equal intervals, and dries the slurry sprayed from the spray nozzles with hot air. In the drying tower, the large number of spray nozzles in the above-mentioned spray stage is divided into several blocks composed of the same number of spray nozzles, and the spray nozzles in each block are always in an open state when they are sequentially opened. The number of spray nozzles to be opened is specified by setting an opening priority such that the spray nozzles are discretely distributed, and by setting a priority order for extracting them discretely between the blocks. At this time, the specified number of spray nozzles determined according to the opening priority of the block are opened from the blocks sequentially extracted by repeating the priority among the blocks. . Further, the nozzle opening/closing control device of the present invention is provided in a spray drying tower in which a large number of spray nozzles are arranged at substantially equal intervals in a required number of spray stages, and slurry sprayed from the spray nozzles is dried with hot air. , a clogging detector is attached to the spray nozzle, and a control device is provided for opening an alternative spray nozzle when the clogging detector detects clogging of the spray nozzle, and the control device is connected to the spray nozzle. The opening priority within each block of the spray nozzle is divided into several blocks in the stage is set in advance, and based on the output signal from the clogged spray nozzle, the next highest opening order within the block to which the clogged spray nozzle belongs is determined in advance. The present invention is characterized in that the priority spray nozzle is opened. Hereinafter, the present invention will be explained in more detail with reference to the drawings. The spray drying tower apparatus to which the method of the present invention is applied is:
The spray drying tower is equipped with one or several spray stages, and in each spray stage, a large number of spray nozzles are arranged at substantially equal intervals around the inner periphery of the drying tower, and the slurry spouted from the spray nozzles is blown by hot air from below. It was made to dry. When controlling the opening and closing of the spray nozzles in the spray drying tower, first, a large number of spray nozzles at the same spray stage are divided into several blocks each composed of the same number of spray nozzles. When considering symmetry etc.,
An even number is better than an odd number, and in consideration of the number of spray nozzles in a spray drying tower in practical use, about 4 is suitable. FIG. 3A shows a case in which 16 spray nozzles are divided into 4 blocks. Additionally, the spray nozzles in each block include
Opening priorities are set such that when the spray nozzles are opened one after another, spray nozzles that are always open are discretely distributed. In this case, if the opening priority is set considering only the symmetry of the open spray nozzles, the open spray nozzles may be densely packed in relation to the adjacent blocks. Priorities need to be established. FIG. 3A and FIGS. 4A to 4C show examples of opening priorities within each block when the number of spray nozzles is different.
It is appropriate to set the release priority in the order of the codes a, b, c, . . . . Note that FIG. 4C shows a case where the spray nozzles are arranged in a double ring shape in one spray stage. When the diameter of the drying tower is large, it is better to double the nozzle arrangement to spray in the center, which improves the uniformity of the spray in the horizontal cross section of the drying tower. For this purpose, it is generally reasonable to give the nozzles in the inner annular array a higher opening priority than the nozzles in the outer annular array. In addition, a priority order for discrete extraction is set between the blocks, and when the spray nozzle is divided into four blocks as illustrated in FIG. It is effective to set a ranking. Furthermore, if there are two spray stages, for example, taking into consideration the vertical overlap within the spray drying tower, the priorities for the first and second stages are set as shown in Figure 3B. is valid. When the number of spray nozzles to be opened is specified, the number of spray nozzles to be opened is determined according to the priority order of opening of the spray nozzles in that block, which is determined by repeating the priority order of blocks ~, that is, from the blocks sequentially extracted in the order of blocks →→→. The spray nozzles that have been opened will be opened one by one until the number specified above is reached, but the spray nozzles that will be opened should be clarified by forming a matrix as shown in Table 1. I can do it. Table 1 is a matrix of nozzle numbers when the number of spray nozzles at the same spray stage is 20 and the number of blocks is 4, with the block name in the row direction and the opening priority within the block in the column direction. With such a matrix, for example, if you want to open 12 spray nozzles,
First, 1, 3, which are displayed in the row direction in the first column.
4. Open the spray nozzle No. 2, move to the next line, and 5.
Number 13,..., and then number 7, 15,... in the next row, totaling 12
By opening the spray nozzles, the

[Table] A pattern like the one shown in Figure 5 can be easily obtained. Of course, the number of open spray nozzles can be increased or decreased by opening and closing them in accordance with the order described above, and if any spray nozzle is blocked due to clogging, the number of open spray nozzles can be increased or decreased until cleaning of that spray nozzle is completed. During this time, it is sufficient to open the spray nozzle with the next highest opening priority in the block to which the spray nozzle belongs. For example, in FIG. 5, if nozzle No. 7 is blocked due to clogging, spray nozzle No. 6, which has the next highest opening priority in the block, is opened as an alternative spray nozzle. and,
Even with alternative spraying using this nozzle, the slurry spray pattern is kept substantially uniform and does not collapse significantly. If you increase or decrease the number of open nozzles or open an alternative spray nozzle by opening and closing such spray nozzles,
By using the above method, it is possible to obtain a spray pattern that is as uniform as possible, and by opening and closing the number of nozzles at that time, it is possible to control the opening and closing of the nozzles in a manner that is optimal for practical use in terms of drying efficiency. can. An apparatus for carrying out the above-mentioned spray nozzle opening/closing control method can be configured as illustrated in FIGS. 6 and 7. In the figure, 1 is a drying tower;
2, 2, ... are a large number of slurry spray nozzles arranged at substantially equal intervals on the spray stage in the drying tower 1, 3 is a hot air outlet provided at the lower part of the drying tower, and the spray nozzles Dry by bringing the raw material slurry ejected from 2 into countercurrent contact with hot air,
The structure is such that the generated granular material is taken out from the bottom 4 of the tower onto a conveyor 5, and hot air is discharged from the top 6 of the tower. The nozzles 2 are arranged annularly at regular intervals, and each nozzle 2 is connected to a pump 9 for pumping slurry through a supply valve 8 through a raw material supply pipe 7, and is connected to a pump 9 for pumping slurry through a water supply pipe 10 through a water supply valve 11. The supply pipe 7 is further equipped with a clogging detector 13 for detecting clogging of the spray nozzle 2, and these valves 8, 11
and a clogging detector 13 are connected to a control device 14 consisting of a computer or the like. As the clogging detector 13, for example, one that detects the sonic waves or ultrasonic waves emitted when the raw material slurry flows through the supply pipe 7 can be used. The control device 14 has a built-in program for obtaining a uniform slurry spray pattern according to the method described above, and by opening and closing the supply valve 8 according to this program, a plurality of sprays in a specific positional relationship can be sprayed. It operates to selectively open the nozzles, thereby uniformly spraying the slurry from these nozzles, and furthermore, if any nozzle becomes clogged during spraying, the clogging A range in which the supply valve 8 is closed and the water supply valve 11 is opened based on the output signal from the detector 13, thereby cleaning the blocked spray nozzle, and at the same time maintaining the uniform slurry spray pattern. In this system, a dormant nozzle is opened as an alternative spray nozzle in place of a blocked spray nozzle. That is, in the above control device, the opening priority within each block of the spray nozzle divided into several blocks in the spray stage and the priority for discrete extraction between blocks are set, for example, in accordance with the matrix in Table 1 above. When the number of nozzles to be used is specified by input from the input device attached to the control device, the number of nozzles to be used is specified by the input from the input device attached to the control device. The supply valve 8 in each spray nozzle is controlled so that the specified number of spray nozzles are opened, and the slurry is sprayed from these nozzles. Furthermore, if any nozzle during spraying is blocked due to clogging, this is detected by the clogging detector 13 and its output signal is input to the control device 14.
The supply valve 8 corresponding to the blocked nozzle is closed, and the opening of the supply valve 8 at the spray nozzle with the next highest opening priority causes it to operate as an alternative spray nozzle, and alternative spraying of the slurry is performed. . At the same time, the water supply valve 11 corresponding to the closed valve is opened, hot water for cleaning is supplied to the nozzle, and cleaning is performed. When the above-mentioned cleaning is completed, the water supply valve 11 is closed and at the same time the water supply valve 8 at that nozzle is closed.
is opened, and furthermore, the supply valve 8 of the alternative nozzle that is being sprayed is closed, and the spray state returns to the state before the nozzle was blocked. The substitute nozzle used for spraying is then cleaned and held inactive again. The number of nozzles to be used is determined by the control device 14.
It can be increased/decreased as appropriate by inputting the value into the , but it can also be automatically increased/decreased over time by setting in advance. As described above, according to the present invention, by selectively opening and closing a large number of nozzles arranged in a spray drying tower using a control device, an open nozzle pattern that can form a uniform slurry spray pattern is selected. This allows spray drying to be carried out under the best thermal conditions and at the same time to obtain the best conditions in terms of product quality. In addition, even when changing the number of nozzles used or using alternative spray nozzles due to clogging, it is possible to always obtain a substantially uniform spray pattern, and the number of nozzle openings and closings is minimized, making it possible to quickly control operating conditions. can.

[Brief explanation of drawings]

1A-C and 2 are explanatory diagrams regarding the conventional opening/closing control of a spray nozzle, and FIGS. 3A, B, 4A-C, and 5 are explanatory diagrams regarding the opening/closing control of the spray nozzle in the present invention. FIG. 6 is a configuration diagram showing an embodiment of the spray nozzle opening/closing control device of the present invention, and FIG.
The figure is an enlarged view of the main parts. 1... Spray drying tower, 2... Spray nozzle, 13...
...Clogging detector, 14...Control device.

Claims (1)

[Scope of Claims] 1. A spray drying tower in which a large number of spray nozzles are arranged at substantially equal intervals in a required number of spray stages, and the slurry spouted from the spray nozzles is dried with hot air, the above-mentioned spray stage A large number of spray nozzles in the spray nozzle are divided into several blocks each consisting of the same number of spray nozzles, and the spray nozzles in each block are discretely arranged so that the spray nozzles are always open when they are sequentially opened. At the same time, the priority order for extracting them discretely between the blocks is set, and when the number of spray nozzles to be opened is specified, the priority order between the blocks is set. A method for controlling the opening and closing of spray nozzles in a spray drying tower, characterized in that the specified number of spray nozzles are opened according to the opening priority order of the blocks sequentially extracted through repetition. 2. When any spray nozzle is blocked due to clogging, the spray nozzle with the next highest opening priority in the block to which the spray nozzle belongs is opened until cleaning of that spray nozzle is completed. A method for controlling the opening and closing of a spray nozzle in a spray drying tower according to claim 1. 3. In a spray drying tower in which a large number of spray nozzles are arranged at a required number of spray stages at substantially equal intervals, and the slurry spouted from the spray nozzles is dried with hot air, a clogging detector is installed in the spray nozzles. At the same time, a control device is provided that opens an alternative spray nozzle when the clogging detector detects clogging of the spray nozzle, and the control device is connected to the spray nozzle divided into several blocks in the spray stage. The opening priority within each block is set in advance, and the spray nozzle with the next highest opening priority within the block to which the clogged spray nozzle belongs is opened based on the output signal from the clogging detector. An opening/closing control device for a spray nozzle in a spray drying tower, characterized in that: