JP3812904B2 - Drying equipment and method for drying powder to be dried - Google Patents

Description

【００２９】
表１より、本実施例は、水冷式ジャケットにより各供給管のジャケットにより被覆されている部分の管内壁が３０〜４０℃に保持され、トナー樹脂の溶融付着は起こらなかったが、比較例では、各供給管の内壁が８０℃に達し、トナー樹脂の溶融付着が確認された。
【００３０】
【発明の効果】
以上詳述のとおり、本発明によれば、被乾燥粉体の管路内の溶融付着を防止され、これにより生ずる管路の詰まりも防止される。
【図面の簡単な説明】
【図１】本発明に係る乾燥設備の概略図である。
【図２】その温度保持手段が設けられている部位の概略図である。
【符号の説明】
１０…乾燥ガス供給装置（ブロア）、１５…フィルタ、２０…加熱手段（非接触型熱交換機）、３０Ａ…第１開閉弁、３０Ｂ…第２開閉弁、４０…定量ホッパー、４５…供給量測定手段、５０…篩装置、５６…排出ガス温度測定手段、６０…分離装置、８０…、ＷＰ…被乾燥粉体、Ｐ…乾燥粉体、Ｇ…乾燥用ガス、Ｇ_H…加熱乾燥用ガス、Ｇ_L…非加熱乾燥用ガス、Ｇ_E…排出ガス、Ｌ１，Ｌ１１，Ｌ１２…主ガス供給管路（経路）、Ｌ１１…加熱経路、Ｌ２…バイパス管路、Ｌ３…被乾燥粉体供給管路（シュート）、Ｌ４…排出管路、Ｃ…冷却媒体、Ｔ…温度計。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drying facility provided with an airflow dryer that disperses a powder to be dried by a drying gas and evaporates a liquid attached to the powder to be dried by the amount of heat of the gas to be dried.
[0002]
[Prior art]
Drying equipment equipped with an airflow dryer is widely used in fields such as the chemical industry and the food industry, and is used for drying powders of synthetic resins, inorganic salts, corn starch, fibers, and the like.
[0003]
In this type of drying equipment, a dry powder supply pipe such as a chute is connected in the middle of the drying gas pipe. A configuration is adopted in which the dry powder is supplied into the airflow dryer while being dispersed, and the liquid adhering to the powder to be dried is evaporated in a short time.
[Patent Literature]
Japanese Patent Publication 8-27132
[0004]
[Problems to be solved by the invention]
However, in this type of drying equipment, the heat of the drying gas is transmitted to the supply pipe and the supply pipe itself is heated. Therefore, when the powder to be dried is supplied to the drying gas, the powder to be dried contacts the supply pipe at a high temperature and melts, and may adhere to and clog the supply pipe. This problem is that the powder to be dried immediately after injection is insufficiently accelerated by the drying gas, and the flow of the drying gas is disturbed at the time of charging, and the dispersion becomes incomplete. It is thought that it occurs. According to the researches of the present inventors, such a melting phenomenon occurs due to contact with the supply pipe in the vicinity of the input portion of the powder to be dried, but the powder to be dried reaches a predetermined speed along the flow of the drying gas. It has been found that almost no melt adhesion occurs when it is fully dispersed. This is presumably because, in the state where the powder to be dried is accelerated, even if the powder to be dried contacts the supply pipe, the contact time is short.
[0005]
Therefore, the main problem of the present invention is to prevent the adhesion of the powder to be dried in the supply pipe, which is considered to be caused by the incomplete dispersion state of the powder to be dried at the time of charging the powder to be dried. It is to prevent clogging of the supply pipe that occurs.
[0006]
[Means for Solving the Problems]
The present invention that has solved the above-described problems and the effects thereof are as follows.
<Invention of Claim 1>
An airflow dryer for drying the powder to be dried by contact between the powder to be dried and a drying gas; a gas supply pipe for sending a drying gas to the airflow dryer; and A heating means for heating the drying gas provided in the middle, and connected to the gas supply pipe at a subsequent stage of the heating means, for feeding the powder to be dried to the drying gas flow flowing through the gas supply pipe A drying facility comprising a dry powder supply pipe and a discharge pipe for discharging the dry powder together with a drying gas from the airflow dryer,
The drying powder supply pipe is connected to the drying gas supply pipe at an acute angle from the upstream side, and the drying gas supply pipe and the drying powder supply pipe include the drying gas supply pipe A drying facility comprising: a connecting portion with a powder supply pipe to be dried and a temperature holding means for holding a predetermined range from the connecting portion at a predetermined temperature.
[0007]
<Invention of Claim 2>
The drying facility according to claim 1, wherein the predetermined range is held below the melting temperature of the powder to be dried by the temperature holding means.
[0008]
<Invention of Claim 3>
A liquid cooling jacket is provided in the gas supply pipe and the dry powder supply pipe over a predetermined range from the connection portion, and a temperature maintaining fluid is circulated through the liquid cooling jacket so that the predetermined range of each supply pipe is provided. The drying equipment according to claim 1, wherein the drying equipment is configured to be maintained at a predetermined temperature.
[0009]
<Invention of Claim 4>
An airflow dryer for drying the powder to be dried by contact between the powder to be dried and a drying gas; a gas supply pipe for sending a drying gas to the airflow dryer; and A heating means for heating the drying gas provided in the middle, and connected to the gas supply pipe at a subsequent stage of the heating means, for feeding the powder to be dried to the drying gas flow flowing through the gas supply pipe A method for drying powder to be dried in a drying facility comprising: a powder supply pipe to be dried; and a discharge pipe for discharging the dry powder together with a drying gas from the airflow dryer,
The dried powder supply pipe in a state where the temperature of the gas supply pipe and the dried powder supply pipe is kept at a predetermined temperature from a connecting portion between the drying gas supply pipe and the dried powder supply pipe. To dry the powder to be dried from an upstream side with respect to the drying gas flowing through the gas supply pipe.
[0010]
<Invention of Claim 5>
The method for drying a powder to be dried according to claim 4, wherein the powder to be dried is charged in a state where the temperature in the predetermined range is kept below the melting temperature of the powder to be dried.
[0011]
<Invention of Claim 6>
A liquid cooling jacket is provided in the gas supply pipe and the dry powder supply pipe over a predetermined range from the connection portion, and a temperature maintaining fluid is circulated through the liquid cooling jacket, thereby reducing the predetermined range of each supply pipe. The method for drying a powder to be dried according to claim 4 or 5, wherein the method is maintained at a predetermined temperature.
[0012]
(Function and effect)
In the present invention, temperature holding means for holding the temperature of the gas supply pipe and the dry powder supply pipe at a predetermined temperature from the connection portion over a predetermined range is provided, and the predetermined range of each supply pipe is held at the predetermined temperature. . Therefore, when the powder to be dried is supplied, the range can be maintained at a temperature at which the powder to be dried does not melt even if it contacts each supply pipe. Further, since the temperature is maintained for a predetermined range, the temperature can be maintained for a range where the powder to be dried is sufficiently accelerated by the drying gas, and reliable melting prevention can be achieved. Here, it is desirable that the predetermined temperature is equal to or lower than the melting temperature of the powder to be dried. By setting such a temperature, melting is reliably prevented. Further, the predetermined range is a range in which at least the powder to be dried is sufficiently accelerated and there is no risk of melting adhesion, and the gas supply pipe has a certain range from the connecting portion toward the dryer side, It is a certain range toward the gas supply source side, and the dried powder supply pipe has a certain range toward the dried powder supply source side rather than the connecting portion. Further, the predetermined range includes a connecting portion. The reason why the temperature is maintained in the range closer to the supply source than the connecting portion is that heat is transmitted through the pipe. The specific numerical values in the predetermined range are appropriately selected depending on the target powder to be dried and the flow velocity and temperature of the drying gas. As such a temperature holding means, a predetermined range of each supply pipe is covered with a liquid cooling jacket, and the predetermined range can be easily determined by circulating a temperature holding fluid in the liquid cooling jacket. Held at temperature.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail below with reference to the drawings.
FIG. 1 is a flowchart showing an outline of the drying equipment according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of a portion to which the temperature holding means is directed.
[0014]
Reference numeral 10 in FIG. 1 denotes a drying gas generator. As for the drying gas G to be generated, dry air, dry inert gas, or the like may be appropriately selected depending on the type of the powder to be dried WP. In the case of using dry air, the drying gas generator 10 can be a blower such as a blower.
[0015]
The drying gas G generated by the drying gas generator 10 is filtered through a filter 15 to remove mixed dust and the like, and then the main gas supply pipe (the pipes passing through the guns L1, L11, and L12 in the figure) and It goes to the airflow dryer 50 through the bypass pipe L2. In the middle of the main gas supply line L11, a non-contact type heat exchanger 20 is installed to heat the drying gas G, and the drying gas is exchanged with the high-temperature steam S by the heat exchanger 20. G is heated to a predetermined temperature (usually about 70 to 180 ° C.). The heating means is not particularly limited to heating by heat exchange with high-temperature steam, and conventionally known heating means for heating the flowing gas can be used. The heating and drying gas _GH heated to a predetermined temperature by heat exchange is further sent to the airflow dryer through the main gas supply lines L11 and L12.
[0016]
The main gas supply line L12 has a chute L3 (hereinafter also referred to as a dry powder supply pipe) for supplying the dry powder WP on the way from the heat exchanger 20 to the airflow dryer 50. .) Is connected, and the powder WP to be dried is supplied from the chute L3 to the drying gas Gi flowing through the main gas supply line L12. On the other hand, a supply hopper 40 that supplies the powder WP to be dried to the chute is installed upstream of the chute L3. A supply amount measuring means 60 for measuring the supply amount of the powder to be dried WP is installed in the middle of the chute L3, and the amount of the powder to be dried WP passing through the chute L3 per unit time is measured. Is done.
[0017]
The to-be-dried powder WP charged into the main gas supply line L12 is sent into the airflow dryer 50 while being diffused by the drying gas Gi flowing through the main gas supply line L12. In the airflow dryer 50, the moisture on the surface of the powder to be dried is evaporated by diffusion of the powder WP to be dried by the airflow and heat exchange by guaranteeing the contact time between the powder WP to be dried and the drying gas Gi. The powder to be dried is dried in a short time. Here, as the airflow dryer 50, a conventionally known airflow dryer that dries the wet substance by contact between the wet substance and the drying gas can be used without any problem. Specific examples include a fluid dryer, a flash dryer, a rotary hot air dryer (worm air dryer), a swirl flow dryer, and the like. In particular, as disclosed in Japanese Patent Publication No. 8-27332, a swirl flow in which a wet substance is supplied into a cylinder in a tangential direction on a drying gas and a swirl flow is generated to dry the wet substance. The type dryer is desirable because the equipment can be downsized.
[0018]
The dry powder, which is dried in a stream dryer within 50 (dry matter) P is discharged to the discharge line L4 along with the drying gas (exhaust gas) G _E. The discharge line L4 is connected to the separation device 60 for separating the gas and the powder such as a cyclone, a dry matter P is separated from the exhaust gas G _E in the separation device.
[0019]
Here, the drying facility of the present embodiment branches at the front stage of the heat exchanger 20 in the main gas supply line, bypasses the heat exchanger 20, and connects the main gas supply line L12 and the chute L3. (Drying powder inlet port) In the previous stage of Z, a bypass line L2 that joins the main gas supply line is provided again. The main gas supply pipe is provided with a first on-off valve 30A between the branch section X and the junction Y with the bypass pipe (hereinafter also referred to as a heating passage L11). By adjusting the opening / closing degree of the on-off valve 30A, the flow rate of the drying gas _GH passing through the heat exchanger 20 is adjusted. A second on-off valve 30B is also provided in the middle of the bypass line L2. By adjusting the degree of opening and closing of the second on-off valve 30B, the airflow dryer 50 passes through the bypass line L2. The flow rate of the drying gas _GL to be directed is adjusted. For this reason, when the first on-off valve 30A is closed and the second on-off valve 30B is opened, the unheated low-temperature drying gas _GL flows after the junction Y, and conversely, the first on-off valve 30A is opened. When the second on-off valve 30B is closed, the heated high-temperature drying gas _GH flows through the connecting portion Z. Further, when both the first on-off valve 30A and the second on-off valve 30B are opened, the drying gas passing through the heating path L11 and the drying gas passing through the bypass pipe L2 merge at the junction Y, and the airflow drying is performed. Head to machine 50. Thus, when opening both the on-off valves 30A and 30B, the gas temperature and the gas flow rate of the drying gas Gi flowing after the junction Y can be adjusted by appropriately operating the on-off degree of the on-off valves 30A and 30B.
[0020]
As the first on-off valve 30A and the second on-off valve 30B, conventionally known means for adjusting the flow rate of the gas flowing in the pipe line, such as a valve, can be used without any problem. The opening degree of the first on-off valve 30A and the second on-off valve 30B, the temperature measuring means for measuring the temperature (usually 35 to 80 ° C.) of the exhaust gas G _E comprises a dry matter P in the middle of the exhaust pipe L4 56 or is adjusted according to the measured value of the supply amount of the wet dry matter WP passing through the chute L3. Here, the operation of each on-off valve 30A, 30B may be performed manually by a facility manager or the like at the site or in a management room, or, for example, the on-off valve is automatically opened and closed according to a known temperature. A known computer control system or the like that operates to a degree may be used.
[0021]
By the way, in this drying equipment, the temperature of each supply pipe L12, L3 which comprises the main gas supply pipe line L12 and the to-be-dried powder supply pipe line L3 over the predetermined range from the said connection part Z is predetermined temperature characteristically. A temperature holding means LJ is provided for holding. The temperature holding means LJ is not particularly limited, and various means used for temperature adjustment and temperature holding of a conventionally known pipe line can be used. In the illustrated example, a liquid cooling jacket LJ is provided over a predetermined range on the outer surface side of each of the supply pipes, and a cooling fluid is circulated through the liquid cooling jacket LJ so that the heat of the supply pipes L12 and L3 and the cooling fluid. By replacement, a predetermined range of each supply pipe is maintained at a predetermined temperature. As described above, if the liquid cooling jacket LJ that keeps the temperature at a predetermined temperature by contact with the cooling fluid is used, the cooling fluid C to be circulated in the liquid cooling jacket LJ is a conventionally known cooling fluid. Among these, it can select suitably according to desired temperature. For example, industrial secondary water can be used. In addition, the operation method of the liquid cooling jacket LJ may be in accordance with a conventionally known technique.
[0022]
The predetermined temperature is a temperature at which melt adhesion does not occur, but this varies depending on the temperature and flow rate of the gas to be dried Gi, the physical properties of the powder to be dried WP, and the like, and is appropriately determined according to these factors. Here, the predetermined temperature is preferably lower than the melting temperature of the powder WP to be dried. This is because if the temperature is equal to or lower than the melting temperature, the powder WP to be dried does not melt even if it adheres to the inner wall of the supply pipe. However, care should be taken not to excessively lower the temperature of the drying gas because excessive drying will result in incomplete drying. Here, the temperature of each of the supply pipes L12 and L3 in the predetermined range can be measured by a conventionally known method by installing a temperature sensor or a thermometer. When measuring the temperature, it is preferable to measure the temperature of the inner wall surface of the tube or a portion close thereto. This is because the material to be dried actually comes into contact with the inner wall surfaces of the supply pipes L12 and L3. Further, when it is difficult to measure the temperature of the inner wall surface, the temperature of the inner wall surface of the supply pipe can be obtained by calculation or the like from the temperature of the outer wall surface and the material of the supply pipe. If the temperature of the temperature holding fluid to be circulated in the water-cooled jacket LJ is determined according to this temperature, the predetermined range of each of the supply pipes L12 and L3 can be held at a predetermined temperature (a temperature at which the melt does not adhere). it can.
[0023]
On the other hand, the predetermined range is a certain range from the connecting portion Z of the dry powder supply pipe L3 and the main gas supply pipe L12 to the fixed hopper 40 for the dry powder supply pipe L3. In L12, it is a certain range from the said connection part Z toward the dryer side and the gas supply source 10 for drying. In determining this range, the range is appropriately determined according to the drying gas Gi and its temperature, the type and physical properties of the powder WP to be dried, and the like. Depending on the temperature of the drying gas Gi, the temperature and physical properties of the powder WP to be dried, there is a possibility that melt adhesion may occur depending on the flow velocity of the drying gas Gi, the inner diameters of the supply pipes L12 and L3, and the materials of the supply pipes L12 and L3. This is because a certain range changes. The predetermined range can be determined in consideration of the melting temperature of the powder WP to be dried. This is because melt adhesion does not occur in the portion where the temperature of the inner walls of the main gas supply pipe L12 and the dry powder supply pipe L3 is lower than the melting point temperature of the dry powder. In addition, since the main gas supply pipe L12 uses heat for drying the powder WP to be dried on the dryer 50 side from the connection portion Z, the temperature decreases from the connection portion Z toward the dryer 50 side. The range in which melt adhesion does not occur can be determined in consideration of this temperature drop.
[0024]
If a liquid-cooled jacket is used as the temperature holding means LJ, it may be provided in a range where the temperature of the inner wall of the tube is the melting temperature of the powder to be dried. It is sufficient to provide a range where the powder to be dried WP may flow backward. Further, the dried powder supply pipe line may be provided in a range where the temperature is equal to or higher than the melting temperature of the dried powder due to heat transfer from the connection portion toward the dried powder supply source.
[0025]
On the other hand, due to the shape of the connecting portion between the powder to be dried supply pipe L3 and the main gas supply pipe L12 and the introduction of the powder to be dried WP, for drying that flows in the main gas supply pipe L12 in the vicinity of the connecting portion Z One of the causes is considered to be disturbance in the flow of the gas Gi. Therefore, in order not to disturb the flow of the drying gas in the vicinity of the connection portion Z due to these causes, the dry powder supply pipe L3 is not connected so as to be orthogonal to the main gas supply pipe L12. As in the illustrated example, the connection part Z is connected to form an acute angle, and the connection is made so as to reduce the turbulence of the flow of the drying gas Gi when the powder to be dried is charged. By configuring the pipe in this way, it is difficult for the flow of the drying gas Gi to be disturbed, which contributes to prevention of melt adhesion.
[0026]
<Example>
When the drying equipment provided with the water-cooled jacket according to the present embodiment of the illustrated example is used and the cooling fluid is circulated and operated while maintaining the temperature of the pipe (Example), the cooling fluid is not circulated. In the case of operation (comparative example), an experiment was conducted as to whether or not melt adhesion in the tube occurred. The operation time (experiment time) of the equipment was about 60 minutes. After the operation time, the inside of the tube was visually confirmed to determine whether there was melt adhesion. The jacketed range is 500 mm from the connecting part to the dryer side for the main gas supply pipe, and 300 mm to the drying gas supply source side for the main gas supply pipe, and the dried powder supply source side from the connection part for the dry powder supply pipe To 100 mm.
[0027]
The experimental conditions were as follows. The type of drying gas was air, and this was used after being heated indirectly to 90 ° C. with steam in a heat exchanger. The flow rate of the drying gas was 25 m / sec. As the powder to be dried, a toner resin having a melting temperature of 45 ° C., an average particle diameter of 5 to 10 μm, and a wetting ratio of 30% was used. The toner resin was charged from the chute to the gas supply pipe at a supply temperature of 20 ° C. and an input amount of 10 to 12 kg / H. The cooling medium used for cooling in the examples was 30 ° C. water, and this was circulated in the jacket at a flow rate of 0.5 to 1.0 m / sec. Table 1 shows the experimental conditions and results.
[0028]
[Table 1]

[0029]
According to Table 1, in this example, the inner wall of the portion covered with the jacket of each supply pipe by the water-cooled jacket was maintained at 30 to 40 ° C., and no melt adhesion of the toner resin occurred. The inner wall of each supply pipe reached 80 ° C., and it was confirmed that the toner resin melted and adhered.
[0030]
【The invention's effect】
As described above in detail, according to the present invention, melt adhesion of the powder to be dried in the pipeline is prevented, and the pipeline clogging caused thereby is also prevented.
[Brief description of the drawings]
FIG. 1 is a schematic view of a drying facility according to the present invention.
FIG. 2 is a schematic view of a portion where the temperature holding means is provided.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Dry gas supply apparatus (blower), 15 ... Filter, 20 ... Heating means (non-contact type heat exchanger), 30A ... 1st on-off valve, 30B ... 2nd on-off valve, 40 ... Metering hopper, 45 ... Supply amount measurement Means 50 ... sieve device 56 ... exhaust gas temperature measuring means 60 ... separation device 80 ... WP ... powder to be dried, P ... dry powder, G ... gas for drying, _GH ... gas for heating and drying, G _L ... non-heat drying gas, G _E ... exhaust gas, L1, L11, L12 ... main gas supply line (path), L11 ... heating path, L2 ... bypass line, L3 ... dry powder supply line (Chute), L4 ... discharge pipe, C ... cooling medium, T ... thermometer.

Claims (6)

An airflow dryer for drying the powder to be dried by contact between the powder to be dried and a drying gas; a gas supply pipe for sending a drying gas to the airflow dryer; and A heating means for heating a drying gas provided in the middle, and connected to the gas supply pipe at a subsequent stage of the heating means, for supplying the powder to be dried to the drying gas flow flowing through the gas supply pipe A drying facility comprising a dry powder supply pipe and a discharge pipe for discharging the dry powder together with a drying gas from the airflow dryer,
The drying powder supply pipe is connected to the drying gas supply pipe at an acute angle from the upstream side, and the drying gas supply pipe and the drying powder supply pipe include the drying gas supply pipe A drying facility comprising: a connecting portion with a powder supply pipe to be dried and a temperature holding means for holding a predetermined range from the connecting portion at a predetermined temperature. The drying facility according to claim 1, wherein the predetermined range is held below the melting temperature of the powder to be dried by the temperature holding means. A liquid cooling jacket is provided in the gas supply pipe and the dry powder supply pipe over a predetermined range from the connection portion, and a temperature maintaining fluid is circulated through the liquid cooling jacket, whereby the predetermined range of each supply pipe is set. The drying equipment according to claim 1, wherein the drying equipment is configured to be maintained at a predetermined temperature. An airflow dryer for drying the powder to be dried by contact between the powder to be dried and a drying gas; a gas supply pipe for sending a drying gas to the airflow dryer; and A heating means for heating a drying gas provided in the middle, and connected to the gas supply pipe at a subsequent stage of the heating means, for supplying the powder to be dried to the drying gas flow flowing through the gas supply pipe A method for drying powder to be dried in a drying facility comprising:
In the state where the temperature of the gas supply pipe and the dry powder supply pipe is maintained at a predetermined temperature from a connecting portion between the drying gas supply pipe and the dry powder supply pipe, the dry powder supply pipe To dry the powder to be dried from an upstream side with respect to the drying gas flowing through the gas supply pipe. The method for drying a powder to be dried according to claim 4, wherein the powder to be dried is charged in a state where the temperature in the predetermined range is kept below the melting temperature of the powder to be dried. A liquid cooling jacket is provided in the gas supply pipe and the dry powder supply pipe over a predetermined range from the connecting portion, and a temperature maintaining fluid is circulated through the liquid cooling jacket, thereby reducing the predetermined range of each supply pipe. The method for drying a powder to be dried according to claim 4 or 5, wherein the method is maintained at a predetermined temperature.

Images