JP6489444B2 - Screw shaft torque constant control method in screw press - Google Patents

Description

The present invention relates to an operation control method for a screw press, and in particular, adjusts the pressure of the stock solution and the dosing rate of the flocculant in order to keep the moisture content of the dewatered cake discharged from the terminal side of the outer cylinder screen constant. The present invention relates to a screw shaft torque constant control method in a screw press that controls the torque of a screw shaft within a predetermined range.

Conventionally, screw presses that concentrate and dehydrate organic sludge such as sewage, human waste, and food production processing wastewater are generally known. A screw press is a device that continuously concentrates and dewaters sludge. Since sludge changes its properties depending on the season, time, weather, etc., a control method such as screw shaft rotation speed, press-fitting pressure, and coagulant supply amount is required to maintain stable performance with a screw press. To do.
For example, Patent Document 1 discloses a screw press that controls the number of revolutions of a stock solution supply pump, the number of revolutions of a screw shaft, and a drug injection rate of a flocculant in order to control the press-fitting pressure of the stock solution supplied to the screw press to a constant level. ing.
In order to make the moisture content of the dewatered cake constant, the screw press is provided with press-in pressure detection means, screw shaft torque detection means, and screw shaft rotation speed control means. A screw press that controls the rotational speed of the screw shaft is described in Patent Document 2.

Japanese Patent No. 50246658 Japanese Patent No. 3542970

The nature of organic sludge such as sewage, human waste, and food production processed wastewater that is concentrated and dewatered by a screw press varies with the season, weather, and time. Various controls were performed on the operation of the screw press or the tempering of the sludge according to this variation.
As described in the patent literature, the control for changing the rotational speed of the screw shaft of the screw press is known, but even a slight fine adjustment of the rotational speed of the screw shaft greatly affects the performance of the screw press. It was difficult.

The screw of the present invention controls the press-fitting pressure and the coagulant injection rate so that the rotational speed of the screw shaft is always constant and the torque of the screw shaft is within a predetermined range so as to cope with fluctuations in the properties of inflowing sewage sludge. Provided is a screw shaft torque constant control method in a press.

The present invention presses and feeds agglomerated slurry obtained by agglomerating the raw liquid sludge to the starting end of the outer cylinder screen, and separates the filtrate from the outer cylinder screen while transporting it to the rear end side of the outer cylinder screen with a rotating screw shaft. In the screw shaft torque constant control method in the screw press that controls the torque of the screw shaft to be constant when the dewatered cake is taken out from the terminal portion of the outer cylinder screen, the reference torque of the screw shaft that has a width in advance and the screw press The reference pressure to be injected, the maximum reference pressure that is the maximum value of the reference pressure, the minimum reference pressure that is the minimum value of the reference pressure, the pressure range of the injection pressure that is increased or decreased step by step, the reference supply amount of the coagulant, and the reference supply A maximum supply amount that is the maximum value, a minimum supply amount that is the minimum value of the reference supply amount, a supply amount range that increases or decreases in stages,
A constant rotation speed of the screw shaft,
Measure the screw shaft torque, and when the measured torque value is within the range of the reference torque, continue the screw press operation, and press fit if the measured torque value is lower than the preset reference torque. Increase the pressure by the pressure range and repeat this operation until the screw shaft torque rises within the range of the reference torque. When the press-fit pressure reaches the maximum reference pressure, increase the supply amount of the flocculant by the supply amount range. This operation is repeated until the torque of the screw shaft rises within the range of the reference torque, and when the measured torque value is higher than the preset reference torque, the press-fit pressure is reduced by the pressure width and the torque of the screw shaft is reduced. This operation is repeated until the pressure falls within the range of the reference torque. When the press-fit pressure reaches the minimum reference pressure, the supply amount of the flocculant is reduced by the supply amount range, and the screw In which torque of repeating this operation until lowered into the range of the reference torque, and controls the torque of the screw shaft at a constant, can be discharged stable dehydrated cake against variation of properties of the sludge.
Also, the press-fitting pressure is adjusted by the supply amount of the agglomerated slurry, the maximum supply amount of the agglomerated slurry, the minimum supply amount, and the supply amount range to be increased or decreased in steps are set in advance, and the measured value of the torque is set in advance. When the torque is lower than the torque, the supply amount of the agglomerated slurry is increased by the supply amount width, and this operation is repeated until the screw shaft torque rises within the range of the reference torque. Increases the supply amount of the flocculant by the supply amount range, repeats this operation until the torque of the screw shaft rises within the range of the reference torque, and if the measured torque value is higher than the preset reference torque, Decrease the slurry supply amount by the supply amount range and repeat this operation until the screw shaft torque falls within the standard torque range. When this happens, the supply amount of the flocculant is decreased by the supply amount range, and this operation is repeated until the screw shaft torque falls within the range of the standard torque. Dewatering operation can be performed in an optimal state of the sludge properties in the filtration chamber.
In addition, by adjusting the press-fitting pressure with the presser opening of the discharge section, and setting the maximum opening of the presser, the minimum opening, and the opening width to be increased or decreased step by step, the measured torque value is the preset reference torque If lower,
Decrease the opening of the presser by the opening width and repeat this operation until the screw shaft torque rises within the range of the standard torque. This is repeated until the screw shaft torque rises within the reference torque range, and if the measured torque value is higher than the preset reference torque, the opening of the presser is This operation is repeated until the screw shaft torque falls within the range of the reference torque.When the opening of the presser reaches the maximum opening, the supply amount of the flocculant is decreased by the supply amount range, This operation is repeated until the torque of the screw shaft falls within the range of the standard torque. There is no sudden change in operation of the screw press, and the sludge properties in the filtration chamber are always in the optimum state. Dehydration can be operated.

According to the present invention, the torque of the screw shaft of the screw press is controlled to be constant, so that a dehydrated cake having a constant moisture content can be always generated with respect to fluctuations in sludge properties. Therefore, the subsequent sludge treatment such as incineration is also stable. Further, since the torque of the screw shaft is controlled by using both the press-fitting pressure and the chemical injection rate, there is no sudden operation change of the screw press, and the sludge property in the filtration chamber can always be dehydrated in an optimum state.

It is a longitudinal cross-sectional view of the screw press which concerns on this invention. Similarly, it is a dehydrator operation control system. Similarly, it is a flowchart of an operation control system.

FIG. 1 is a longitudinal sectional view of a screw press. The screw press 1 is a screw shaft in which screw blades 6 are wound around an outer cylindrical screen 5 having a filtration surface on the periphery between frames 3 and 4 before and after a gantry 2. 7 is installed. The screw shaft 7 disposed inside the outer cylinder screen 5 increases in diameter in a tapered manner from the start end side to the end end side, and the outer cylinder screen 5 and the screw shaft 7 are spaced relative to each other in the extending direction. I try to decrease. A sludge supply pipe 8 is connected to the front end portion of the screw shaft 7, and the supply pipe 8 communicates with a supply hole 9 of the screw shaft 7 opened on the start end side of the outer cylinder screen 5. A screw drive shaft 10 is connected to the rear end portion of the screw shaft 7, and a drive sprocket 11 is fitted to the screw drive shaft 10. The sprocket 11 is driven by a screw driver 12 to rotate the screw shaft 7. The sludge supplied from the supply hole 9 is transferred from the start end side to the end end side by the screw blade 6 and is concentrated and dehydrated while separating the filtrate from the outer cylinder screen 5. The outer cylinder screen 5 may be rotatable as required.
In the screw press 1, the dewatered cake discharge unit 13 that discharges sludge (dehydrated cake) immediately after performing the dewatering process to the outside has a tapered cone shape for applying back pressure to the discharged dehydrated cake. A presser (pressing plate) 14 is provided. The presser 14 is provided so as to reciprocate in the axial direction (left-right direction in FIG. 1) by a fluid pressure cylinder 15 such as an air cylinder or a hydraulic cylinder.
The screw press 1 can continuously dehydrate the agglomerated slurry, and is smaller and more compact than conventional continuous dehydrators such as belt-type dehydrators and centrifugal dehydrators. It is. Moreover, the screw press 1 can exhibit a stable filtration action by maintaining the inside of the filtration chamber at the optimum pressure, and can perform continuous dehydration at the optimum moisture content.

FIG. 2 is a schematic configuration diagram of a constant screw shaft torque control method in the screw press according to the present invention, and an operation control system thereof will be described. The processing stock solution such as sludge stored in the sludge storage tank 20 is supplied to the agglomeration mixing tank 23 through the stock solution supply pipe 22 by the stock solution supply pump 21 at the stock solution flow rate QS. In the middle of the stock solution supply pipe 22, a stock solution flow meter 24 for measuring the stock solution flow rate QS of the processing stock solution is provided between the stock solution supply pump 21 and the coagulation mixing tank 23. A densitometer may be provided as necessary.
Further, in the middle of the stock solution supply pipe 22 between the stock solution flow meter 24 and the coagulation / mixing tank 23, the solution is supplied from the polymer solution tank 25 in which the polymer flocculant is stored by the chemical solution supply pump 26 at the chemical solution flow rate QP. A chemical solution supply pipe 27 is connected. In the middle of the chemical liquid supply pipe 27, a chemical liquid flow meter 28 for measuring the chemical liquid flow rate QP is provided between the chemical liquid supply pump 26 and the stock liquid supply pipe 22.
The end of the stock solution supply pipe 22 is connected to the lower side of the closed type agglomeration mixing tank 23, and sludge to which a polymer flocculant is added is pressed from the lower side of the agglomeration mixing tank 23, mixed and stirred by the stirrer 29 to agglomerate. A slurry is produced. A slurry supply pipe 30 is connected to the upper part of the agglomeration mixing tank 23, and the other end of the slurry supply pipe 30 is connected to the screw press 1, and is agglomerated in the supply pipe 8 of the screw press 1 shown in FIG. The slurry is press-fitted and supplied at the tank pressure of the agglomeration mixing tank 23. A pressure gauge 31 is disposed in the slurry supply pipe 30 to measure the press-fitting pressure PS of the agglomerated slurry supplied to the screw press 1.
A torque meter 32 is disposed in the drive shaft system (for example, the screw drive shaft 10) of the screw press 1, and measures the torque of the screw shaft 7 that increases or decreases due to fluctuations in sludge properties. The torque T measured by the torque meter 32 and a preset reference torque T0 are compared and determined, and the load on the screw shaft 7 is adjusted so as to be the reference torque T0.
Specifically, a command is given to the stock solution supply pump 21 or the chemical solution supply pump 26, and the stock solution flow rate QS and the chemical solution flow rate QP are increased or decreased, respectively, to perform a constant torque control operation. Actually, the detection signal measured by the torque meter 32 is transmitted to the control device 33, the control device 33 makes a comparison and judgment, and the control device 33 gives a command to the stock solution supply pump 21 or the chemical solution supply pump 26.
Control of the stock solution flow rate by the stock solution supply pump 21 mainly affects the press-fit pressure to the screw press 1, and the press-fit pressure increases or decreases in proportion to the stock solution flow rate. Further, the control of the chemical flow rate by the chemical supply pump 26 mainly affects the floc strength of the agglomerated slurry supplied to the screw press 1. The floc strength increases or decreases in proportion to the chemical flow rate, and the press-fitting pressure to the screw press 1 is increased. Also increase or decrease.
When the press-fitting pressure to the screw press 1 increases, the load on the screw shaft 7 increases and the torque of the screw shaft 7 increases. On the contrary, when the press-fitting pressure to the screw press 1 decreases, the load on the screw shaft 7 decreases and the torque of the screw shaft 7 decreases.

The operation control method according to the present invention is based on controlling the torque of the screw press 1 to be constant in order to operate the screw press 1 stably. Therefore, in order to make the torque constant, the stock solution flow rate and the chemical solution flow rate supplied to the screw press 1 are controlled.
When the operation of the screw press 1 is started, the torque of the screw shaft 7 is measured by the torque meter 32 in real time and sent to the control device.

In general, when the properties of the inflow sludge change and the amount of solid matter in the treated sludge increases (decreases), the press-fitting pressure supplied to the screw press 1 increases (decreases), and the screw shaft 7 changes in accordance with the load variation. Torque increases (decreases).
Therefore, in the control device of the present invention, the measured value T of the torque meter 32 is compared with the preset reference torque T0, and when the measured value T deviates from the reference torque T0, the stock solution supply pump 21 or the chemical solution supply pump A command is given to No. 26 to control the supply amount of the coagulation slurry or the supply amount of the coagulant, thereby increasing or decreasing the solid matter amount of the aggregation slurry. By adjusting the operating load on the screw press 1, the torque of the screw press 1 can be easily maintained at the reference torque T0.

The reference torque T0 can be set with a certain range, and when the measured torque value T is within the set range, the normal operation is continued while maintaining the current state.
More specifically, when the measured torque value T is lower than the reference torque T0, the control device 33 gives a command to the stock solution supply pump 21 to increase the supply amount of the agglomerated slurry. The torque of the screw press 1 can be increased by supplying the tempered sludge having an increased solid content to the screw press 1. If the torque measurement value T does not return to the reference torque T0 even if the supply amount of the coagulated slurry is increased, a command is given from the control device 33 to the chemical solution supply pump 26 to increase the supply amount of the coagulant. The torque of the screw press 1 can be increased by supplying the tempered sludge having an increased floc floc strength to the screw press 1.

  On the other hand, when the measured value T of the torque is higher than the reference torque T0, the control device 33 gives a command to the stock solution supply pump 21 to decrease the supply amount of the agglomerated slurry. The torque of the screw press 1 can be lowered by supplying the tempered sludge having a reduced solid content to the screw press 1. If the torque measurement value T does not return to the reference torque T0 even if the supply amount of the coagulated slurry is decreased, a command is given from the control device 33 to the chemical solution supply pump 26 to reduce the supply amount of the coagulant. The torque of the screw press 1 can be lowered by supplying the tempered sludge having weakened flocs floc strength to the screw press 1.

  By adjusting the press-fitting pressure while increasing / decreasing the supply amount of the coagulation slurry and the supply amount of the coagulant, the torque of the screw press 1 can be easily controlled within the reference value, and the stable operation of the screw press can be continued. Can do.

  Once the supply amount of the stock solution supply pump 21 or the chemical solution supply pump 26 is changed, the torque is measured again after a predetermined time has elapsed, and the above operation is repeated until the measured value T returns to the reference torque T0.

A supply amount range in which the supply amount of the coagulation slurry and the supply amount of the coagulant are increased or decreased in a stepwise manner is set in advance. An upper limit and a lower limit of the supply amount of the coagulation slurry and the supply amount of the coagulant may be set, and an alarm may be issued when the upper limit or the lower limit is reached, or the operation may be automatically stopped for investigation. Moreover, you may set the upper limit and lower limit of the press-fit pressure supplied to the screw press 1 instead of the supply amount of the aggregation slurry. In that case, a pressure width for increasing or decreasing the press-fitting pressure stepwise is set in advance.
As another example, the opening degree of the presser (pressing plate) 14 of the dewatered cake discharge unit 13 is a factor that affects the press-fitting pressure to the screw press 1 as well as the supply amount of the agglomerated slurry by the stock solution supply pump 21.
When the opening degree of the presser 14 is increased, the press-fitting pressure of the screw press 1 is decreased and the torque of the screw shaft 7 is decreased. Conversely, when the opening degree of the presser 14 is reduced, the press-fitting pressure of the screw press 1 is increased and the torque of the screw shaft 7 is increased.

FIG. 3 is a flowchart of the operation control system according to this embodiment.
A. The reference torque T0 (maximum reference torque Tmax, minimum reference torque Tmin) of the initial setting screw shaft 7 is set. In this embodiment, a range between the maximum reference torque Tmax and the minimum reference torque Tmin is set as the reference torque T0.
A reference pressure P0, a maximum pressure Pmax, a minimum pressure Pmin, and a pressure width p that are increased or decreased step by step when the coagulated slurry is pressed into the screw press 1 are set.
A reference supply amount A0, a maximum supply amount Amax, a minimum supply amount Amin, and a supply amount width a that is increased or decreased step by step are set.
It should be noted that the maximum supply amount Qmax and the minimum supply amount Qmin of the coagulated slurry for adjusting the press-fitting pressure, the supply amount width q to be increased or decreased stepwise, and the maximum opening Bmax and the minimum opening Bmin of the presser 14 are increased or decreased stepwise. The opening width b is set.
B. Start of operation Each device is operated at the reference values T0, P0, A0 and the rated value N.
C. Torque comparison The torque of the screw shaft 7 of the screw press 1 is measured and compared with the reference torque T0.
When the measured value T of the torque is within the reference torque T0, the operation of each device is maintained in the current state.
When the measured value T is smaller than the reference torque T0, the process proceeds to D in the flowchart, and control is performed to increase the press-fitting pressure of the coagulating slurry supplied to the screw press 1 or the coagulant supply amount stepwise.
When the measured value T is larger than the reference torque T0, the process proceeds to E in the flowchart, and control is performed to reduce the supply amount of the coagulant or the press-fitting pressure of the coagulated slurry supplied to the screw press 1 in a stepwise manner.
D. Pressurization pressure comparison In the flowchart C, when the measured torque value T is smaller than the reference torque T0, the pressure width p that is increased stepwise is taken into account in order to increase the supply amount of the agglomerated slurry in order to increase the pressurization pressure. The pressure P is compared with the maximum pressure Pmax.
If the post-change press-fit pressure P is smaller than the maximum pressure Pmax, control proceeds to F in the flowchart and the press-fit pressure is increased stepwise.
When the post-change press-fit pressure P is equal to or higher than the maximum pressure Pmax, the process proceeds to G in the flowchart, and control is performed to increase the supply amount of the flocculant stepwise.
F. Press-fit pressure (increase)
In the flowchart D, when the measured value P of the press-fit pressure after change is smaller than the maximum pressure Pmax, control is performed to increase the press-fit pressure by a preset pressure width p.
Specifically, the stock solution supply pump 21 is adjusted to increase the supply amount of the aggregate slurry by a preset supply amount width q. In that case, the supply amount Q that takes into account the supply amount width q that is increased stepwise in the flowchart D may be compared with the maximum supply amount Qmax.
Further, as another means, the opening degree of the presser 14 of the screw press 1 may be adjusted and decreased by a preset opening degree width b. In that case, you may compare and judge the opening degree B which considered the opening degree width | variety b reduced in steps D of the flowchart, and the minimum opening degree Bmin.
G. Comparison of the maximum supply amount of the flocculant In the above flow chart D, when the measured value P of the press-fit pressure is equal to or greater than the maximum pressure Pmax, the supply amount range that is increased stepwise to increase the flocculant in order to increase the press-fit pressure. The supply amount A taking into account a and the maximum supply amount Amax are compared.
When the changed supply amount A of the flocculant is smaller than the maximum supply amount Amax, the control proceeds to H in the flowchart and the control is performed to increase the supply amount of the flocculant stepwise.
If the supply amount A of flocculant after the change is the maximum supply amount Ama x or more, the routine proceeds to the flowchart of I, or raise an alarm, or performs control to automatically stop the operation of the screw press 1.
H. Flocculant supply amount (increase)
In the flowchart G, when the changed supply amount A of the coagulant is smaller than the maximum supply amount Amax, the chemical liquid supply pump 26 is adjusted to perform control to increase the supply amount of the coagulant by a preset supply amount range a. Do.
I. Torque is measured again after a certain period of alarm / operation stop, and the above operation is repeated until the measured value returns to the reference torque. If the measured value of torque does not return to the reference value even when the coagulant reaches the maximum supply amount or the minimum supply amount, an alarm is issued or the operation of the screw press 1 is automatically stopped.
E. Comparison of press-fitting pressure In the flowchart C, when the measured torque value T is larger than the reference torque T0, the pressure width p that is reduced stepwise is taken into account in order to reduce the supply amount of the agglomerated slurry in order to lower the press-fitting pressure. The pressure P is compared with the minimum pressure Pmin.
When the press-fit pressure P after the change is larger than the minimum pressure Pmin, the process proceeds to J in the flowchart and control is performed to decrease the press-fit pressure stepwise.
When the post-change press-fit pressure P is equal to or lower than the minimum pressure Pmin, the process proceeds to K in the flowchart, and control is performed to gradually reduce the supply amount of the flocculant.
J. et al. Press-fit pressure (reduction)
In the flowchart E, when the measured value P of the press-fit pressure after the change is larger than the minimum pressure Pmin, the stock solution supply pump 21 is adjusted to perform control to reduce the press-fit pressure by a preset pressure width p.
Specifically, the stock solution supply pump 21 is adjusted to reduce the supply amount of the aggregate slurry by a preset supply amount width q. At that time, the supply amount Q that takes into account the supply amount width q that is gradually reduced in E in the flowchart may be compared with the minimum supply amount Qmin.
As another means, the opening degree of the presser 14 of the screw press 1 may be adjusted to increase the opening degree width b set in advance. In that case, the opening degree B that takes into account the opening degree width b that is increased stepwise at K in the flowchart may be compared with the maximum opening degree Bmax.
K. Comparison of the minimum supply amount of the flocculant In the above flow chart E, when the measured value P of the press-fit pressure is equal to or less than the minimum pressure Pmin, the supply amount range to be decreased stepwise in order to reduce the flocculant to lower the press-fit pressure. The supply amount A including a is compared with the minimum supply amount Amin.
When the changed supply amount A of the coagulant is larger than the minimum supply amount Amin, the control proceeds to L in the flowchart to control the supply amount of the coagulant in a stepwise manner.
When the supply amount A of the flocculant after the change is equal to or less than the minimum supply amount Amin, the process proceeds to M in the flowchart, and an alarm is issued or control for automatically stopping the operation of the screw press 1 is performed.
L. Flocculant supply (decrease)
In the flowchart K, when the changed supply amount A of the coagulant is larger than the minimum supply amount Amin, the chemical solution supply pump 26 is adjusted to perform control to decrease the supply amount of the coagulant by a preset supply amount range a. Do.
M.M. Torque is measured again after a certain period of alarm / operation stop, and the above operation is repeated until the measured value returns to the reference torque. If the measured value of torque does not return to the reference value even when the coagulant reaches the maximum supply amount or the minimum supply amount, an alarm is issued or the operation of the screw press 1 is automatically stopped.
When the press-fitting pressure or the supply amount of the flocculant is changed, the press-fitting pressure is measured again after a predetermined time has elapsed, and the above operation is repeated until the measured value T returns to the reference torque T0.

The screw shaft torque constant control method in the screw press of the present invention can maintain stable dewatering performance by adjusting the load on the screw shaft and controlling the torque to be constant. Accordingly, the present invention can be applied to various solid-liquid separators, particularly continuous screw presses, for solid-liquid separation of sewage sludge whose properties of the processing stock solution are constantly changing depending on the season and weather.

1 Screw press 5 Outer cylinder screen 7 Screw shaft T0 Reference torque Tmax Maximum reference torque Tmin Minimum reference torque P0 Reference pressure Pmax Maximum pressure Pmin Minimum pressure p Pressure range to be increased or decreased stepwise A0 Reference supply amount Amax Maximum supply amount Amin Minimum supply amount a Supply amount range Qmax to be increased or decreased stepwise Maximum supply amount Qmin Minimum supply amount q Supply amount range to be increased or decreased stepwise Bmax Maximum opening Bmin Minimum opening b Opening range to increase or decrease stepwise

Claims (3)

The agglomerated slurry obtained by agglomerating the raw liquid sludge is press-fitted and supplied to the starting end of the outer cylinder screen (5) and conveyed to the rear end side of the outer cylinder screen (5) by the rotating screw shaft (7). In the screw shaft torque constant control method in the screw press that controls the torque of the screw shaft (7) to be constant when separating the filtrate from the outer cylindrical screen (5) and taking out the dehydrated cake from the terminal portion,
Reference torque (T0) of the screw shaft (7) having a width in advance,
Reference pressure (P0) for press-fitting into the screw press, maximum reference pressure (Pmax) that is the maximum value of the reference pressure, minimum reference pressure (Pmin) that is the minimum value of the reference pressure, and the pressure width of the press-fit pressure that is increased or decreased stepwise (P) and
The reference supply amount (A0) of the flocculant, the maximum supply amount (Amax) that is the maximum value of the reference supply amount, the minimum supply amount (Amin) that is the minimum value of the reference supply amount, and the supply amount range that increases or decreases in stages ( a) and
A constant rotation speed of the screw shaft,
Set
Measure the torque (T) of the screw shaft (7),
When the measured torque value (T) is within the range of the reference torque (T0), the screw press operation is continued.
When the measured value (T) of the torque is lower than the preset reference torque (T0),
Increase the press-fitting pressure by the pressure width (p) and repeat this operation until the torque of the screw shaft (7) rises within the range of the reference torque (T0),
When the press-fit pressure reaches the maximum reference pressure (Pmax), the supply amount of the flocculant is increased by the supply amount width (a), and the torque of the screw shaft (7) rises within the range of the reference torque (T0). Repeat this operation until
When the measured value (T) of torque is higher than a preset reference torque (T0),
This operation is repeated until the press-fit pressure is reduced by the pressure width (p) and the torque of the screw shaft (7) is lowered within the range of the reference torque (T0).
When the press-fitting pressure becomes the minimum reference pressure (Pmin), the supply amount of the flocculant is decreased by the supply amount width (a), and the torque of the screw shaft (7) falls within the range of the reference torque (T0). This method is repeated until the screw shaft torque constant control method in the screw press. Adjust the press-fitting pressure with the supply amount of the agglomerated slurry,
The maximum supply amount (Qmax), minimum supply amount (Qmin), and supply amount range (q) to be increased or decreased in stages are set in advance,
When the measured value (T) of the torque is lower than the preset reference torque (T0),
Increase the supply amount of the agglomerated slurry by the supply amount range (q), and repeat this operation until the torque of the screw shaft (7) rises within the range of the reference torque (T0),
When the supply amount of the coagulated slurry reaches the maximum supply amount (Qmax), the supply amount of the coagulant is increased by the supply amount range (a), and the torque of the screw shaft (7) is within the range of the reference torque (T0). Repeat this operation until it rises to
When the measured value (T) of torque is higher than a preset reference torque (T0),
This operation is repeated until the supply amount of the agglomerated slurry is reduced by the supply amount width (q), and the torque of the screw shaft (7) falls within the range of the reference torque (T0),
When the supply amount of the coagulated slurry becomes the minimum supply amount (Qmin), the supply amount of the coagulant is decreased by the supply amount range (a), and the torque of the screw shaft (7) is within the range of the reference torque (T0). The screw shaft torque constant control method in the screw press according to claim 1, wherein the operation is repeated until the screw shaft descends. Adjust the press-fitting pressure with the opening of the presser (14) of the discharge part,
Reference torque in which the measured value (T) of the torque is set in advance by setting the maximum opening (Bmax), the minimum opening (Bmin), and the opening width (b) to be increased or decreased step by step. If lower than (T0),
The opening of the presser (14) is decreased by the opening width (b), and this operation is repeated until the torque of the screw shaft (7) rises within the range of the reference torque (T0).
When the opening degree of the presser (14) becomes the minimum opening degree (Bmin), the supply amount of the flocculant is increased by the supply amount width (a), and the torque of the screw shaft (7) becomes the reference torque (T0). Repeat this operation until it rises within range,
When the measured value (T) of torque is higher than a preset reference torque (T0),
Increase the opening of the presser (14) by the opening width (b), and repeat this operation until the torque of the screw shaft (7) falls within the range of the reference torque (T0),
When the opening of the presser (14) reaches the maximum opening (Bmax), the supply amount of the flocculant is decreased by the supply amount width (a), and the torque of the screw shaft (7) is reduced to the reference torque (T0). The screw shaft torque constant control method in the screw press according to claim 1, wherein the operation is repeated until it falls within a range.

Images