Sludge drying and heating kettle

Abstract

To provide a sludge drying and heating kettle that can determine the optimal time to stop the drying process.SOLUTION: The sludge drying and heating kettle for drying sludge comprises a kettle body that can store and heat sludge, and a condition sensor that can detect the drying condition of sludge.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sludge drying heating kiln for drying sludge. [Background technology]

[0002] In order to reduce the volume of industrial waste, techniques for drying sludge have been proposed. For example, Patent Document 1 describes a technique for drying sludge using a biomass burner that uses wood chips as fuel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-47971 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when drying sludge, if the drying is insufficient, the amount of sludge waste increases, and if the drying is excessive, dust becomes a problem. Therefore, it is necessary to determine the appropriate time to end the drying.

[0005] Previously, a technique for determining the time to end drying by measuring the weight of sludge has been proposed. However, weight measurement does not allow for the determination of the ratio of water to sludge material, making it impossible to determine the moisture content. Therefore, it is difficult to determine the appropriate time to end drying based on the change in weight.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sludge drying heating vessel that can determine an appropriate time to terminate drying. [Means for solving the problem]

[0007] (1) The sludge drying and heating furnace of the present invention is a furnace for drying sludge, and comprises a furnace body capable of storing and heating sludge, and a state sensor capable of detecting the drying state of the sludge.

[0008] In the sludge drying and heating oven (1), the oven body dries the sludge while a status sensor detects the sludge's drying status. When the moisture content reaches a level where dust generation is minimal and drying efficiency is good, the oven body stops the drying operation. As described above, the sludge drying and heating oven can determine the appropriate time to end drying.

[0009] (2) The sludge drying and heating vessel further includes an agitator having an agitating blade for agitating the sludge, and the status sensor detects the load acting on the agitating blade.

[0010] In the sludge drying and heating tank (2), the dryness of the sludge is detected based on the load acting on the agitator blades. Therefore, the dryness of the sludge can be detected accurately. In contrast, weight sensors sometimes cannot accurately detect the dryness of the sludge because they measure the weight of the sludge including the weight of the entire device, and infrared temperature sensors sometimes cannot accurately detect the dryness of the sludge due to sensor contamination.

[0011] The sludge drying and heating furnace (3) further includes a control unit that determines the drying state of the sludge. The control unit terminates heating by the furnace body at a transition point when the load acting on the agitator blades changes from increasing to decreasing, or at any point within a predetermined time range including before and after the transition point.

[0012] In the sludge drying and heating oven (3), the control unit determines the drying state of the sludge based on the change in the load acting on the agitator blades, and therefore the oven can determine the appropriate time to end the drying.

[0013] (4) In the sludge drying heating vessel, the control unit predicts the time until heating by the vessel body is completed based on the value of the load acting on the stirring blade.

[0014] In the sludge drying heating vessel (4), the time required to complete drying is predicted based on the value of the load acting on the agitator blades. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a sludge drying heating vessel that can determine an appropriate time to terminate drying. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing the general configuration of a sludge drying heating furnace according to a first embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a block diagram showing the control configuration of the sludge drying heating furnace. [Figure 3] 10 is a flowchart showing a sludge drying control operation. [Figure 4] 10 is a graph showing the change in moisture content and torque over time during sludge drying operation. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1. First embodiment (1) Basic structure of the drying and heating furnace A sludge drying heating oven 1 (hereinafter referred to as "heating oven 1") will be described using Figure 1. The heating oven 1 is an apparatus for drying sludge by heating the sludge while stirring it. Figure 1 is a schematic diagram showing the general configuration of a sludge drying heating oven according to a first embodiment of the present invention.

[0018] The heating kettle 1 mainly includes a kettle body 3, a steam generator 4, and an agitator 5.

[0019] (2) Detailed configuration of the sludge drying heating tank The kettle body 3 is a container for storing sludge. The kettle body 3 is a hollow container with a bottom that opens upward. In FIG. 1, the kettle body 3 is a generally horizontally oriented cylinder disposed with its axis along the left-right direction, and both left and right ends thereof are closed by end walls 3a that bulge outward in a generally arc-like shape in the left-right direction. A generally rectangular cylindrical hopper 3b is provided at the top of the peripheral side wall, excluding the left and right ends, and opens upward. The pot body 3 is rotatable about its axis and can discharge sludge downward (described later).

[0020] The steam generator 4 is a heating device and includes a jacket 11 and a steam supply device 12.

[0021] Jacket 11 is a member that heats the inside of kettle body 3 by supplying steam. Jacket 11 is provided so as to cover approximately the lower half of kettle body 3. Specifically, jacket material 11a is provided on the outside of approximately the lower half of kettle body 3, giving kettle body 3 a double-wall structure, and the space between kettle body 3 and jacket material 11a forms jacket 11.

[0022] A jacket steam supply port 7 and a jacket drain discharge port 8 are provided at the lower end of the jacket 11. More specifically, in the state shown in Fig. 1 (with the upper opening of the kettle body 3 facing upward), the jacket steam supply port 7 is provided in the center of the jacket 11 in a plan view (the center in the left-right direction and the center in the front-back direction), and the jacket drain discharge port 8 is provided spaced apart from the jacket steam supply port 7 in the left-right direction.

[0023] The steam supply device 12 is a device that supplies steam into the jacket 11. Specifically, the steam supply device 12 has a steam supply source (not shown) and a steam supply pipe 9 connected to the jacket steam supply port 7. The steam supply device 12 supplies steam from the steam supply source connection port through the steam supply pipe 9 and from the jacket steam supply port 7 into the jacket 11.

[0024] The heating oven 1 has a drain discharge device 15. The drain discharge device 15 discharges steam condensate (drain) from inside the jacket 11. Specifically, the drain discharge device 15 has a drain discharge pipe 16 leading to the outside, which is connected to the jacket drain discharge port 8. The drain discharge device 15 discharges condensate from the jacket drain discharge port 8 through the drain discharge pipe 16 to the outside of the apparatus.

[0025] The agitator 5 is a device that agitates the sludge in the pot body 3. The agitator 5 has an agitator blade 18 that agitates the sludge, an agitation mechanism 19, and a rotation drive unit 20 (Fig. 2). A plurality of agitator blades 18 (four in this embodiment) are provided. The agitation mechanism 19 has a rotation shaft 21 that spans the left and right sides of the pot body 3. The rotation shaft 21 is disposed along the axis of the pot body 3 and is rotatably supported at both the left and right ends of the pot body 3. The extension of the rotation shaft 21 to the right of the pot body 3 is connected to the rotation drive unit 20. The rotation drive unit 20 includes a motor, a reduction mechanism, etc. The agitator blade 18 has an agitator portion 18a that rotates together with the rotary shaft 21 to agitate the sludge, and a support portion 18b that has one end connected to the rotary shaft 21 and the other end connected to the agitator portion 18a.

[0026] The heating pot 1 has a torque sensor 31 (status sensor). The torque sensor 31 can detect the drying state of the sludge. Specifically, the torque sensor 31 is a sensor (for example, a strain gauge torque sensor) that detects the load acting on the agitator blade 18. The torque sensor 31 is provided on the support portion 18b of the agitator blade 18. That is, a total of four torque sensors 31 are provided. The torque sensor 31 may be provided between the support portion 18b and the rotating shaft 21, or may be provided between the support portion 18b and the agitator 18a.

[0027] The control unit 41 (described later) can determine the dryness state (moisture content) of the sludge based on the torque (load) acting on the agitation blade 18. The relationship between the dryness state (moisture content) of the sludge and the torque acting on the agitation blade 18 is stored in advance in the control unit 41.

[0028] The moisture content of the sludge decreases over time during the drying operation. As the moisture content of the sludge decreases, the viscosity of the sludge increases, and the torque acting on the agitator blade 18 also increases. Then, in the next stage, when the moisture content of the sludge increases further, the sludge becomes dry and flaky, and the torque acting on the agitator blade 18 decreases.

[0029] The heating oven 1 further includes a base 32, a side frame 33, and a drive box 34. The oven main body 3 is suspended from the base 32 and is rotatably held at both left and right ends by the side frames 33 and the drive box 34, which are provided on the left and right sides of the base 32. A tilting mechanism (not shown) within the drive box 34 enables the oven main body 3 to tilt so that the upper opening faces forward (toward the viewer in FIG. 1). The drive box 34 is provided with a control unit 41 (described below), and also houses the tilting mechanism for the oven main body 3 and the rotation drive unit 20 for the agitator 5. The tilting mechanism and the rotation drive unit 20 are controlled by the control unit 41.

[0030] (3) Control configuration of the sludge drying heating tank The control configuration of the heating pot 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control configuration of the sludge drying heating pot. The heating pot 1 has a control unit 41.

[0031] The control unit 41 is a computer system having a processor (e.g., a CPU), a storage device (e.g., a ROM, a RAM, a HDD, an SSD, etc.), and various interfaces (e.g., an A / D converter, a D / A converter, a communication interface, etc.) The control unit 41 performs various control operations by executing programs stored in the storage device (corresponding to part or all of the storage area of ​​the storage device).

[0032] The control unit 41 controls the steam generator 4 and the agitator 5. This allows the steam generator 4 to be heated and the agitator blade 18 to rotate, thereby drying the sludge. The control unit 41 can change the amount of steam generated by the steam generator 4 and the rotation speed of the agitator blade 18.

[0033] The control unit 41 can determine the dryness state of the sludge based on the detection results of the torque sensors 31. Specifically, the control unit 41 determines the dryness state of the sludge by detecting the load acting on the agitator blades 18. As a result, the control unit 41 can determine the appropriate time to end the drying. As a result, the control unit 41 performs drying control until the moisture content of the sludge reaches the set value. The load on the agitator blades 18 is obtained from the detection results of the four torque sensors 31.

[0034] (4) Control operation of the sludge drying heating tank The control operation of the sludge drying heating pot will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the sludge drying control operation.

[0035] The control flowcharts described below are merely examples, and steps can be omitted or replaced as necessary. Furthermore, multiple steps can be executed simultaneously, or some or all of the steps can be executed in an overlapping manner.

[0036] Furthermore, each block in the control flowchart is not limited to a single control operation, but can be replaced with a plurality of control operations represented by a plurality of blocks. The operation of each device is the result of commands from the control unit to each device, and these are expressed by each step of the software application.

[0037] In step S1, sludge is introduced into the vessel body 3. The moisture content of the sludge is, for example, 70 to 85%. It is preferable that the sludge has been dehydrated in advance.

[0038] In step S2, the steam generator 4 heats the sludge. Specifically, the control unit 41 controls the steam generator 4 to supply high-temperature steam to the jacket 11.

[0039] In step S3, the sludge is agitated by the agitation blade 18. Specifically, the control unit 41 causes the rotation drive unit 20 to drive the agitation blade 18. Note that step S2 and step S3 may start either first or simultaneously. The control unit 41 controls the steam generating device 4 and the agitating device 5 based on the detection signal from the torque sensor 31.

[0040] In step S4, the drying completion time is predicted. Specifically, the control unit 41 predicts the drying completion time required to reach the optimum moisture content based on the value of the torque acting on the stirring blade 18.

[0041] In step S5, it is determined whether the actual drying time has exceeded the predicted time by a predetermined time. Specifically, the control unit 41 makes this determination. If the actual drying time has exceeded the predicted time by the predetermined time, the process proceeds to step S10, where abnormality handling is performed. The abnormality handling includes, for example, stopping the operation of the steam generator 4, stopping the rotation of the agitator blades 18, and issuing an alarm. This prevents the sludge from over-drying.

[0042] In step S6, it is determined whether or not the torque satisfies a predetermined condition (that is, whether or not the moisture content of the sludge has reached an appropriate value). Specifically, the control unit 41 executes the above determination.

[0043] The changes in moisture content and torque over time during the sludge drying operation will be explained using Figure 4. Figure 4 is a graph showing the changes in moisture content and torque over time during the sludge drying operation. Note that the graph in Figure 4 has been simplified for the purpose of explanation.

[0044] As shown in FIG. 4, the moisture content W gradually decreases.

[0045] As shown in Figure 4, the torque T gradually increases, reaches a peak, and then gradually decreases. This is because the torque T increases as the viscosity of the sludge increases over time, and then as the sludge dries (the sludge breaks down into many clumps or small pieces), the torque T decreases.

[0046] A first example of the "predetermined condition" in step S6 is when the torque acting on the agitating blade 18 reaches a transition point X1 at which the torque transitions from increasing to decreasing.

[0047] A second example of the "predetermined condition" described above is when any point within a time range Y1 around the conversion point X1 (including before and after the conversion point X1) is reached. This makes it possible to prevent the sludge from being insufficiently or excessively dried.

[0048] In step S7, the steam generator 4 stops heating. Specifically, the control unit 41 stops the operation of the steam generator 4.

[0049] In step S8, the stirring operation of stirring blade 18 is stopped. Specifically, control unit 41 stops the operation of rotation drive unit 20. Note that step S7 and step S8 may start either first or simultaneously.

[0050] In step S9, sludge is discharged from inside the tank body 3. Specifically, the control unit 41 drives the tilting mechanism to tilt the tank body 3. The final moisture content of the sludge is, for example, 50 to 30%.

[0051] (5) Effects As described above, the torque sensor 31 provided on the agitator blade 18 performs feedback control based on the torque value, and the sludge is dried to an appropriate moisture content. In other words, an increase in the amount of sludge waste due to insufficient drying is suppressed, and furthermore, dust problems due to over-drying are suppressed.

[0052] 2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the gist of the invention. In particular, the multiple embodiments and modifications described in this specification can be arbitrarily combined as necessary.

[0053] The heating vessel may have a weight sensor or an infrared temperature sensor for measuring the moisture content of the sludge. In this case, the weight sensor or the infrared temperature sensor can be used to check whether the moisture content of the sludge is appropriate.

[0054] The calculation of the predicted drying end time and the determination of whether or not that time has exceeded the predetermined time may be omitted. The predicted drying completion time may be calculated based on the weight of the sludge before the drying process.

[0055] The heating device may employ other heating means other than steam, such as an electric heater. The structure, position and number of stirring arms of the stirring device are not particularly limited.

[0056] The torque sensor may be a capacitance type, a magnetostrictive type, or an optical type torque sensor in addition to a strain gauge type torque sensor.

[0057] 3. Contribution to the United Nations-led Sustainable Development Goals (SDGs) This disclosure includes matters that contribute to achieving Goal 6 of the SDGs (Sustainable Development Goals), "Clean water and sanitation," and Goal 9, "Industry, innovation and infrastructure." [Explanation of symbols]

[0058] 1: Sludge drying heating tank 3: Kettle body 4: Steam generator 5: Stirring device 11: Jacket 12: Steam supply device 18: Stirring blade 19: Stirring mechanism 20: Rotation drive unit 31: Torque sensor (status sensor) 41: Control unit

Claims

1. A sludge drying heating vessel for drying sludge, The boiler body can store and heat sludge, A sludge drying and heating kettle equipped with a status sensor that can detect the drying state of sludge.

2. Further provided is an agitation device having an agitation blade for agitating the sludge, 2. The sludge drying and heating vessel according to claim 1, wherein the condition sensor detects a load acting on the agitating blade.

3. Further, a control unit is provided to determine the dryness state of the sludge, The sludge drying heating tank described in claim 2, wherein the control unit terminates heating by the tank body at a transition point when the change in load acting on the agitator blade changes from increasing to decreasing, or at any point within a predetermined time range including before and after the transition point.

4. 4. The sludge drying and heating furnace according to claim 3, wherein the control unit predicts the time required for the furnace body to finish heating based on the value of the load acting on the agitating blade.

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