JPH11315999A - Transfer system for sedimenting slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sedimentating slurry transfer system having a novel structure, which needs no displacement type pumps. SOLUTION: A sedimenting slurry transfer system 10 transfers sedimenting slurry such as sewage from a transfer origin tank 2 to a transfer destination tank 14 through a transfer pipe 16. In this case, the system is provided with a centrifugal pump 18 provided as a pump for boosting the sedimenting slurry, an electric motor 20 for rotary-driving the centrifugal pump 18, an inverter 22 as a pulsation generating mechanism for variably controlling speed of the electric motor 20, thus the centrifugal pump, and a variable speed control condition input device 24 for entering a variable speed control condition to the inverter 22. The variable speed control condition input device is composed of a flowmeter 26 provided in the transfer pipe 16 and a timer 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a settling slurry transfer system, and more particularly to a transfer system for transferring a settled slurry at a high flow rate and economically using a vortex pump. .

[0002]

2. Description of the Related Art Sewage sludge is a sludge generated when sewage is treated by an activated sludge method or the like, and is a typical settling slurry having a property that suspended solids in the slurry settle. Sewage sludge is pipe-pumped from the sewage treatment plant in the form of concentrated sludge with a high moisture content, and is intensively incinerated at large sludge incineration plants, or sent to the dehydrator in the form of concentrated sludge and dewatered. It is often incinerated after being made into a dehydrated cake. In the conventional settling slurry transfer system 50, as shown in FIG. 5, when transferring the sewage sludge from the transfer source tank 12 to the transfer destination tank 14 by pipe pressure transfer via the transfer pipe 16, as a pressurizing pump,
Conventionally, sewage sludge is pressurized using a positive displacement pump 52 such as a stroke pump or a snake pump, and is pumped through the transfer pipe 16.

A stroke pump is also referred to as a reciprocating pump, and is a pump that reciprocates a piston or plunger in a cylinder provided with a suction valve and a discharge valve to pressurize a fluid such as a sedimentable slurry. Snake pump
A helically twisted metal rotor rotates in a stator made of synthetic rubber, Teflon, etc., and as the rotor rotates, a displacement chamber formed between the rotor and the stator moves from the suction side to the discharge side. It is a pump that pumps a fluid such as a settling slurry by moving.

[0004]

Most displacement pumps such as a stroke pump have a small flow rate, and are necessary for transferring a large amount of fluid in a short time, such as the transfer of sewage sludge. Large flow positive displacement pumps are very expensive and often are not economically viable. Further, the positive displacement pump has a complicated structure, and when used for pumping a liquid containing suspended solids such as a sedimentable slurry, there is a problem that the pump is liable to break down and the maintenance cost is increased. Accordingly, an object of the present invention is to provide a settling slurry transfer system having a novel configuration that does not require a positive displacement pump.

[0005]

SUMMARY OF THE INVENTION The present inventor has considered using a spiral pump capable of transferring a fluid at a large flow rate instead of a positive displacement pump. Researched the behavior of and found the following. (1) When pumping fluid by a stroke pump,
From the principle of pressure increase of the stroke pump, the flow rate of the fluid to be pumped shows a pulsation that changes in a regular pulse shape along the time axis as shown in FIG. When the fluid pumped in the pipe pulsates, the fluid is a settling slurry, and even if suspended solids settle from the settling slurry to the bottom of the pipe, the fluid of the slurry in which the settled solids pulsate is used. Stirred by the mechanical energy and returned into the slurry again. Thereby, even if the fluid is a sedimentable slurry, it can be transferred. (2) On the other hand, according to the flow rate characteristics of the centrifugal pump, the flow rate is constant with respect to the time axis as shown in FIG. Therefore, if the vortex pump is used as it is as a pump for transferring the sedimentable slurry, suspended solids in the slurry will deposit on the transfer pipe, block the pipe, and become unable to be transferred in a short time.

The inventor of the present invention has proposed a pulsation generating mechanism by operating a centrifugal pump on and off in a regular cycle or by providing a valve in a transfer pipe and opening and closing the valve regularly. With the idea that the flow characteristics of the centrifugal pump are approximated to the flow characteristics of the positive displacement pump, the present inventors have completed experiments through repeated experiments.

In order to achieve the above object, a settling slurry transfer system according to the present invention (hereinafter referred to as a first invention) is a system for transferring a settling slurry by a pipe pumping method. A spiral pump for increasing the pressure of the slurry, an electric motor for rotating the spiral pump,
The first period is a first rotation speed set value, and the second period is a second rotation speed set value different from the first rotation speed set value, and the first period and the second rotation speed set value are different from each other. And an inverter that controls the rotation speed of the electric motor at a variable speed so that the centrifugal pump rotates by alternately repeating the period and the first and second periods, and the first and second periods as variable speed control conditions. And a variable speed control condition input device for inputting the rotation speed set value to the inverter.

In the first aspect, the rotational speed of the centrifugal pump and the rotational speed of the electric motor have a fixed relationship. For example, when the rotating shaft of the spiral pump is directly connected to the rotating shaft of the electric motor, the rotating speed of the spiral pump and the rotating speed of the electric motor are the same, and a transmission is provided between the spiral pump and the electric motor. In some cases, the speed of the centrifugal pump and the speed of the electric motor follow the speed ratio. The pulsation generating mechanism includes an inverter and a variable speed control condition input device, and the variable speed control conditions, that is, the first and second periods and the first and second rotation speed set values flow through the transfer pipe. This is a set condition for pulsating the settling slurry. The variable speed control conditions vary depending on the pipe diameter and pipe route of the transfer pipe, the flow rate and properties of the settling slurry, and are determined in advance by experiments and the like. As used herein, the sedimentable slurry refers to a slurry having a property that suspended solids in the slurry settle. For example, in the first invention, the settling slurry is discharged at a low flow rate during the first period in which the centrifugal pump rotates at the first rotational speed set value, and the second rotational speed is higher than the first rotational speed set value. The settling slurry is discharged at a high flow rate during the second period in which the centrifugal pump rotates at the rotation speed set value. Thereby, the settling slurry flowing through the transfer pipe is in a pulsating state. Conversely, the first rotational speed setting is high, so that the settling slurry is discharged at a high flow rate and the second
Therefore, the settling slurry may be discharged at a low flow rate.

As the variable speed control condition input device used in the first invention, for example, a device such as a sequencer that stores a preset variable speed control condition and outputs it to an inverter is used. In addition, a flow meter is provided for measuring the flow rate of the settling slurry flowing in the transfer pipe connected to the discharge side of the centrifugal pump. Each time the measured value of the flow meter reaches the upper limit set value or the lower limit set value, the inverter controls the variable speed. A device that outputs control conditions may be used.

A settling slurry transfer system according to the present invention (hereinafter, referred to as a second invention) is a system for transferring a settling slurry by a pipe pumping method, comprising: a spiral pump for increasing the pressure of the settling slurry; Two automatic on-off valves having valve diameters different from each other and provided in parallel with a transfer pipe connected to the discharge side of the centrifugal pump;
One of the two automatic opening / closing valves is opened and the other is closed, and then, during a second period, one is closed and the other is opened, and the first period and the second period are alternately repeated to obtain a second period. And a sequencer for controlling the opening and closing of the automatic on-off valves.

In the second invention, the valve diameters of the two automatic on-off valves and the first and second periods are set conditions capable of pulsating the settling slurry flowing through the transfer pipe, It depends on the flow rate and properties of the settling slurry, the diameter of the transfer pipe, and the pipe route, and is determined in advance by experiments and the like. The sequencer outputs a command to the automatic opening / closing valve according to a preset opening / closing schedule of the two automatic opening / closing valves, and opens and closes one of the two automatic opening / closing valves for a first predetermined period. During a second predetermined period, a valve opening / closing operation of closing one and opening the other is performed alternately and regularly.

A settling slurry transfer system (hereinafter referred to as a third invention) according to the present invention is a system for transferring a settling slurry by a pipe pumping method, comprising: a spiral pump for increasing the pressure of the settling slurry; A flow control valve provided on a transfer pipe connected to the discharge side of the volute pump,
A flow control device for controlling the flow rate of the settling slurry by adjusting the flow control valve;
, A first flow rate set value, and then a second time period, a second flow rate set value different from the first flow rate set value, and setting of the first and second time periods. And a sequencer that alternately repeats

In the third aspect of the present invention, the valve diameter of the flow rate control valve, the large flow rate set value and the small flow rate set value as the flow rate set value of the flow control device, and the first and second periods are the same as the transfer pipe. Is a set condition that can pulsate the settling slurry flowing through the settling slurry, which varies depending on the flow rate and properties of the settling slurry, the pipe diameter of the transfer pipe, and the pipe route, and is determined in advance by experiments or the like.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 This embodiment is an example of the first embodiment of the present invention, and FIG. 1 is a flow sheet showing the configuration of a settling slurry transfer system of this embodiment. As shown in FIG. 1, a settling slurry transfer system 10 of the present embodiment is a system for transferring a settling slurry, for example, sewage sludge, from a transfer source tank 12 to a transfer destination tank 14 via a transfer pipe 16. A vortex pump 18 provided as a pressurizing pump for the settling slurry, an electric motor 20 for rotating the vortex pump 18, and a pulsation generating mechanism,
An inverter 22 for controlling the electric motor 20 at a variable speed and a variable speed control condition input device 24 for inputting a variable speed control condition to the inverter 22 are provided.

The centrifugal pump 18 is a centrifugal pump of a known configuration suitable for the transfer flow rate of the settling slurry, and is rotationally driven by an electric motor 20 having a rotary shaft directly connected to the rotary shaft of the rotary pump 18. Therefore, the rotation speed of the volute pump 18 and the rotation speed of the electric motor are the same. The inverter 22 alternately repeats the first period and the second period, and sets the first period to the first rotation speed set value, and then sets the second period to the first rotation speed set value. Controls the variable speed of the electric motor 20 so that the electric motor 20, and thus the centrifugal pump 18, rotates at a different second rotational speed setting. In the present embodiment, the settling slurry is discharged at a low flow rate during the first period in which the electric motor 20 rotates at the first rotational speed set value, and the second rotational speed is higher than the first rotational speed set value. During the second period in which the electric motor 20 rotates at the rotation speed set value, the settling slurry is discharged at a high flow rate. Thereby, the settling slurry flowing through the transfer pipe is in a pulsating state. Conversely, the first rotational speed setting is high, and thus the settling slurry is discharged at a high flow rate during the first period, and the second second rotational speed setting is low, and thus during the second period. Alternatively, the settling slurry may be discharged at a low flow rate.

The rotation speed set value input device 24 is connected to the transfer pipe 1.
6 includes a flow meter 26 and a timer 28. When the measured value of the flow meter 26 reaches the upper limit set value, the flow meter 26 outputs a signal to that effect to the inverter 22, and the inverter 22 outputs the signal at the second rotation speed set value during the second period. The variable speed control of the motor 20 is performed. When the second period elapses, a signal to that effect is input from the timer 28 to the inverter 22, and the inverter 22 operates the electric motor 20 at a first rotation speed set value lower than the second rotation speed set value.
Variable speed control. Thereby, the flow rate of the settling slurry is reduced. When the measured value of the flow meter 26 reaches the lower limit set value, the flow meter 26 outputs a signal to that effect to the inverter 22, and the inverter 22 operates at the first rotation speed set value for the first period. The variable speed control of the motor 20 is performed. When the first period elapses, the timer 28 informs the inverter 2 to that effect.
2, the inverter 22 performs variable speed control of the electric motor 20 at the second rotation speed set value. As a result, the flow rate of the settling slurry increases, and the value measured by the flow meter 26 again reaches the upper limit set value. Hereinafter, this is repeated.

As a result, the settling slurry flowing through the transfer pipe 16 pulsates, as shown in FIG. 2, so that the settled slurry does not settle the settled suspension in the settled slurry. The transfer from the transfer source tank 12 to the transfer destination tank 14 is performed stably via the transfer tank 16. Incidentally, as the variable speed control condition input device 24, a device such as a sequencer which stores preset variable speed control conditions and outputs it to the inverter may be used.

Embodiment 2 This embodiment is an example of the second embodiment of the present invention, and FIG. 3 is a flow sheet showing the configuration of a settling slurry transfer system of this embodiment. As shown in FIG. 3, the settling slurry transfer system 30 of the present embodiment transfers the settling slurry from the transfer source tank 12 to the transfer destination tank 14 via the transfer pipe 16 as in the first embodiment. This system has the same configuration as the configuration of the first embodiment except that the configuration of the pulsation generating mechanism 32 is different.

The pulsation generating mechanism 32 is provided in parallel on the discharge side of the centrifugal pump 18 of the transfer pipe 16 and has two automatic opening / closing valves 34 and 36 having different valve diameters and two automatic opening / closing valves 34. , 36 for controlling the opening and closing of the power supply. The sequencer 38 outputs a command to the automatic open / close valves 34, 36 according to a preset open / close schedule of the automatic open / close valves 34, 36, and opens one of the two automatic open / close valves 34, 36 for the first period. At the same time, the other 36 is closed, and then, during the second period, the valve opening / closing operation of closing the one 34 and opening the other 36 is performed regularly.

As a result, the settling slurry flowing through the transfer pipe 16 pulsates as shown in FIG. 2, so that the settled slurry can be transferred without causing the settled suspension in the settled slurry to settle. The transfer from the transfer source tank 12 to the transfer destination tank 14 is performed stably via the transfer tank 16.

Embodiment 3 This embodiment is an example of the third embodiment of the present invention, and FIG. 4 is a flow sheet showing the structure of a settling slurry transfer system of this embodiment. As shown in FIG. 4, the settling slurry transfer system 40 of the present embodiment transfers the settling slurry from the transfer source tank 12 to the transfer destination tank 14 via the transfer pipe 16 as in the first embodiment. This system has the same configuration as that of the first embodiment except that the configuration of the pulsation generating mechanism 42 is different.

The pulsation generating mechanism 42 includes a flow control valve 44 provided on the discharge side of the spiral pump 18 of the transfer pipe 16,
A flow control device 46 that controls the flow by adjusting the flow control valve 44 and a sequencer 48 are provided. The sequencer 48 sets the flow set value of the flow control device 46 to a first flow set value for a first period, and then sets the flow set value for a second period.
The second flow rate is set to a smaller value than the first flow rate, and the setting of the first period and the second period is alternately repeated. The flow control device 46 sets the first flow rate set value during the first period according to a command from the sequencer 48, and then sets the second flow rate set value smaller than the first flow set value during the second period. Set.

As a result, the settling slurry flowing through the transfer pipe 16 pulsates as shown in FIG. 2, so that the settled slurry can be transferred without settling the settled suspension in the settled slurry. The transfer from the transfer source tank 12 to the transfer destination tank 14 is performed stably via the transfer tank 16.

[0024]

According to the present invention, by providing the pulsation generating mechanism, the settling slurry can be transferred by using a vortex pump, which is technically difficult in the conventional settling slurry transfer system. This makes it possible to use a centrifugal pump instead of a positive displacement pump, which has a low flow rate, many failures, is expensive, and has a high maintenance cost. Can be transported.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a configuration of a settling slurry transfer system of a first embodiment.

FIG. 2 is a diagram showing a state of pulsation.

FIG. 3 is a flow sheet showing a configuration of a settling slurry transfer system of a second embodiment.

FIG. 4 is a flow sheet showing a configuration of a settling slurry transfer system of a third embodiment.

FIG. 5 is a flow sheet showing a configuration of a conventional settling slurry transfer system.

FIG. 6 is a diagram showing flow characteristics of a positive displacement pump.

FIG. 7 is a view showing flow characteristics of a centrifugal pump.

[Explanation of symbols]

 Reference Signs List 10 transfer system of settling slurry of embodiment 1 12 transfer source tank 14 transfer destination tank 16 transfer pipe 18 centrifugal pump 20 electric motor 22 inverter 24 variable speed control condition input device 26 flow meter 28 timer 30 settling of second embodiment Slurry transfer system 32 Pulsation generation mechanism 34, 36 Automatic opening / closing valve 38 Sequencer 40 Settling slurry transfer system of Embodiment 3 42 Pulsation generation mechanism 44 Flow control valve 46 Flow control device 48 Sequencer 50 Conventional settling slurry Transfer system 52 positive displacement pump

Claims (4)

[Claims] 1. A system for transferring sedimentable slurry by a pipe pumping method, comprising: a spiral pump for increasing the pressure of the sedimentary slurry; an electric motor for rotating and driving the spiral pump; Then, the second period is set to a second rotation speed set value different from the first rotation speed set value, and the first period and the second period are alternately repeated. An inverter that controls the rotation speed of the electric motor at a variable speed so that the motor rotates; and a variable speed control condition in which the first and second periods and the first and second rotation speed set values are input to the inverter. A settling slurry transfer system, comprising: a shift control condition input device. 2. A variable speed control condition input device, which stores a preset variable speed control condition and outputs the variable speed control condition to an inverter, or a sedimentation flow device that flows through a transfer pipe connected to the discharge side of a centrifugal pump. 2. The apparatus according to claim 1, further comprising a flowmeter for measuring a flow rate of the slurry, wherein the apparatus outputs a variable speed control condition to the inverter every time a measured value of the flowmeter reaches an upper limit set value or a lower limit set value. Settling slurry transfer system. 3. A system for transferring a sedimentable slurry by a pipe pumping method, comprising: a spiral pump for increasing the pressure of the sedimentary slurry; and a transfer pipe having a valve diameter different from each other and connected to a discharge side of the spiral pump. , Two automatic on-off valves provided in parallel with each other, a first period, one of the two automatic on-off valves is opened and the other is closed, and then, during a second period, one is closed and the other is closed. A sedimentary slurry transfer system, comprising: a sequencer that is opened and controls opening and closing of two automatic on-off valves by alternately repeating a first period and a second period. 4. A system for transferring sedimentable slurry by a pipe pumping method, comprising: a spiral pump for increasing the pressure of the sedimentary slurry; a flow control valve provided on a transfer pipe connected to a discharge side of the spiral pump; A flow control device for controlling the flow rate of the settling slurry by adjusting the flow control valve; setting a flow rate set value of the flow control device to a first flow rate set value for a first period; A sequencer for setting a period and a second flow rate set value different from the first flow rate set value, and a sequencer which alternately repeats the setting of the first time period and the second time period. Transport system.