Digestion system and heating control method

Abstract

To provide a digestion system and a heating control method for accurately controlling a temperature within a tank.SOLUTION: A system comprises: a first tank that performs digestion of sludge; a first pipe that supplies surplus sludge to the first tank; a second pipe that circulates digested sludge between the inside and the outside of the first tank; a first temperature adjuster that heats, with a first fluid, at least one of the surplus sludge in the first pipe and the digested sludge in the second pipe; a second temperature adjuster that heats, with a second fluid, at least one of the surplus sludge and the digested sludge that have undergone heating in the first temperature adjuster; and a control device that, based on a temperature related to digestion, controls at least one of heating of the surplus sludge in the first pipe by the first temperature adjuster, heating of the digested sludge in the second pipe by the first temperature adjuster, heating of the surplus sludge in the first pipe by the second temperature adjuster, and heating of the digested sludge in the second pipe by the second temperature adjuster.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a fire extinguishing system and a method for controlling heat. [Background technology]

[0002] In a digestion system having a tank (hereinafter also referred to as a digestion tank) for digesting the material to be treated (for example, organic matter contained in primary sludge and excess sludge), a technology has been proposed that achieves efficient digestion of the material to be treated by maintaining the temperature inside the tank at an appropriate temperature (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special table 2011-516246 publication Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described fire extinguishing system, for example, it is desirable to precisely control the temperature inside the tank so that the temperature inside the tank is maintained at an appropriate temperature. [Means for solving the problem]

[0005] The digestion system of the present disclosure comprises a first tank for digesting sludge, a first pipe for supplying excess sludge to the first tank, a second pipe for circulating the digested sludge in the first tank between the first tank and the outside, a first temperature regulator for heating at least one of the excess sludge in the first pipe and the digested sludge in the second pipe with a first fluid, a second temperature regulator for heating at least one of the excess sludge and the digested sludge heated in the first temperature regulator with a second fluid, and a control device for controlling at least one of the heating of the excess sludge in the first pipe by the first temperature regulator, the heating of the digested sludge in the second pipe by the first temperature regulator, the heating of the excess sludge in the first pipe by the second temperature regulator, and the heating of the digested sludge in the second pipe by the second temperature regulator based on the temperature related to the digestion. [Effects of the Invention]

[0006] The extinguishing system and heating control method disclosed herein make it possible to precisely control the temperature inside the tank. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a processing system 1000 according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of the temperature adjustment system 100 according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating the hardware configuration of the control device 200 in the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the function of the control device 200 in the first embodiment. [Figure 5] FIG. 5 is a flowchart illustrating the temperature control process in the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating the configuration of a temperature adjustment system 100 in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, such descriptions should not be interpreted in a limiting sense, and do not limit the subject matter described in the claims. Furthermore, various changes, substitutions, and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, different embodiments can be combined as appropriate.

[0009] [Processing System 1000 in the First Embodiment] First, a processing system 1000 according to the first embodiment will be described. Fig. 1 is a diagram illustrating the configuration of the processing system 1000 according to the first embodiment.

[0010] The treatment system 1000 in this embodiment is, for example, a water treatment system that treats liquid such as sewage (hereinafter also referred to as water to be treated).

[0011] 1, the treatment system 1000 includes, for example, a primary sedimentation tank 10, a tank 20 (hereinafter also referred to as a reaction tank 20), a final sedimentation tank 30, a thickening device 40, a thickening device 50, a tank 60 (hereinafter also referred to as a digestion tank 60), a temperature adjustment system 100, and a control device 200. Note that, hereinafter, the treatment system 1000 will also be referred to as a digestion system 1000.

[0012] The primary sedimentation tank 10 separates, for example, organic and other contaminants (e.g., solid organic matter) contained in the water to be treated. The separated contaminants (hereinafter also referred to as primary sludge) are then discharged to a concentration device 40 by, for example, a pump (not shown). The water to be treated after the separation of contaminants by sedimentation is then discharged to a digestion tank 60 by, for example, a pump (not shown).

[0013] The reaction tank 20 is a tank that treats the water to be treated by biological treatment such as the standard activated sludge method. Specifically, the reaction tank 20 decomposes organic matter (e.g., soluble organic matter) contained in the water to be treated, for example, by microorganisms (hereinafter also referred to as activated sludge) propagated in the reaction tank 20. Then, after the organic matter has been decomposed by the activated sludge, the water to be treated is discharged from the reaction tank 20 to the final sedimentation tank 30 by, for example, overflow.

[0014] The final settling tank 30, for example, separates and discharges activated sludge contained in the water to be treated discharged from the reaction tank 20. Then, a part of the settled and separated activated sludge (hereinafter also referred to as excess sludge) is discharged to the thickening device 50, for example, by a pump (not shown). Another part of the settled and separated activated sludge (hereinafter also referred to as returned sludge) is returned to the reaction tank 20, for example, by a pump (not shown). Furthermore, the water to be treated after the activated sludge separation is discharged to a downstream sterilization treatment device (not shown) by, for example, overflow. Thereafter, the sterilization treatment device sterilizes the water to be treated discharged from the final settling tank 30, for example, and discharges the sterilized treated water into a river or the like.

[0015] The thickening device 40 thickens, for example, the primary sludge discharged from the primary sedimentation tank 10. The thickened primary sludge is then discharged into the digestion tank 60 by, for example, a pump (not shown). The liquid separated from the primary sludge by thickening is returned to the primary sedimentation tank 10 by, for example, a pump (not shown).

[0016] The thickening device 50 thickens, for example, excess sludge discharged from the final settling tank 30. The thickened excess sludge is then discharged to the digestion tank 60 by, for example, a pump (not shown). Note that the liquid separated from the excess sludge by the thickening is returned to the final settling tank 30 by, for example, a pump (not shown).

[0017] In the digestion tank 60, for example, anaerobic bacteria in the digestion tank 60 anaerobically digest (decompose) organic matter contained in the primary sludge supplied from the thickener 40 and the excess sludge supplied from the thickener 50 through a biological reaction, thereby producing digested sludge. Specifically, the anaerobic bacteria in the digestion tank 60 produce digestion gases such as methane gas (hereinafter simply referred to as digestion gas) during the digestion process. Note that the temperature of the digested sludge (digestion liquid) in the digestion tank 60 is preferably maintained between 35°C and 39°C (hereinafter, this temperature range is also referred to as the optimum temperature) in order to efficiently promote biological reactions and improve the digestion rate.

[0018] The temperature adjustment system 100 adjusts the temperature of the excess sludge before it is supplied to the digestion tank 60, for example. Specifically, the temperature adjustment system 100 heats the excess sludge before it is supplied to the digestion tank 60, for example.

[0019] Furthermore, the temperature adjustment system 100 adjusts, for example, the temperature of digested sludge (digested sludge supplied from the digestion tank 60) in the digestion tank 60. Specifically, the temperature adjustment system 100 heats, for example, the digested sludge in the digestion tank 60. The temperature adjustment system 100 will be described below.

[0020] [Temperature Adjustment System 100 in the First Embodiment] FIG. 2 is a diagram illustrating the configuration of the temperature adjustment system 100 according to the first embodiment.

[0021] As shown in FIG. 2, the temperature adjustment system 100 in this embodiment includes, for example, a temperature adjuster 110 (hereinafter also referred to as the first temperature adjuster 110), a temperature adjuster 120 (hereinafter also referred to as the second temperature adjuster 120), a storage tank 130, a pump P1, and a pump P2.

[0022] The storage tank 130 is, for example, a tank that stores excess sludge supplied from the concentrating device 50 via a line L1. The line L1 is, for example, a pipe that connects the concentrating device 50 and the storage tank 130.

[0023] Pump P1 is provided, for example, on line L2, and supplies excess sludge from storage tank 130 to temperature regulator 110, supplies excess sludge whose temperature has been adjusted by temperature regulator 110 to temperature regulator 120, and further supplies excess sludge whose temperature has been adjusted by temperature regulator 120 to digestion tank 60. Line L2 is, for example, a pipe that sequentially connects storage tank 130, temperature regulator 110, temperature regulator 120, and digestion tank 60. Hereinafter, line L2 will also be referred to as the first pipe.

[0024] Furthermore, pump P1 supplies excess sludge, the temperature of which has been adjusted by temperature regulator 110, to digestion tank 60 via line L5, for example. Line L5 is, for example, a pipe connecting line L2, which is between temperature regulator 110 and temperature regulator 120, with digestion tank 60. In other words, line L5 is, for example, a pipe that bypasses temperature regulator 120. Hereinafter, line L5 will also be referred to as a bypass pipe.

[0025] Pump P2 is provided, for example, on line L6, and supplies digested sludge from the digestion tank 60 to the temperature regulator 110, and then supplies digested sludge whose temperature has been adjusted by the temperature regulator 110 to the digestion tank 60 via lines L6 and L2. Line L6 is, for example, a pipe connecting the digestion tank 60 to a position on line L2 between pump P1 and the temperature regulator 110. Hereinafter, line L6 and the portion of line L2 between the junction with line L6 and the digestion tank 60 will be collectively referred to as the second pipe. In other words, the first pipe, for example, shares a portion of the pipe (hereinafter also referred to as partial pipe) with the second pipe.

[0026] The temperature regulator 110 heats, for example, excess sludge supplied from the concentrator 50 via line L2. The temperature regulator 110 also heats or cools, for example, digested sludge supplied from the digester 60 via lines L6 and L2. Specifically, the temperature regulator 110 is, for example, a heat exchanger that adjusts the temperature of at least one of the excess sludge and the digested sludge using a fluid (for example, a fluid such as hot water or cooling water) circulating through line L3. The line L3 is, for example, a circulation pipe that connects the temperature regulator 110 to a heat source (not shown) or a refrigerant source (not shown).

[0027] The temperature regulator 120 heats, for example, excess sludge supplied from the temperature regulator 110 via line L2. The temperature regulator 120 also heats, for example, digested sludge supplied from the temperature regulator 110 via line L2. Specifically, the temperature regulator 120 is, for example, a heat exchanger that heats at least one of the excess sludge and the digested sludge using a fluid (e.g., a fluid such as hot water) circulating through line L4. The line L4 is, for example, a circulation pipe that connects the temperature regulator 120 to a heat source (not shown).

[0028] The fluid (e.g., hot water) supplied to the temperature regulator 120 may be a fluid with a higher temperature than the fluid (e.g., hot water or cooling water) supplied to the temperature regulator 110. Specifically, the heat source for heating the fluid supplied to the temperature regulator 120 may be, for example, a heat exchanger that heats the fluid using waste heat from exhaust gas generated in an incinerator (not shown) that incinerates the digested sludge discharged from the digester tank 60. The heat source for heating the fluid supplied to the temperature regulator 120 may be, for example, a heat exchanger that heats the fluid using waste heat generated in conjunction with power generation using the digester gas discharged from the digester tank 60. The heat source for heating the fluid supplied to the temperature regulator 120 may be, for example, a water heater that heats the fluid using the digester gas discharged from the digester tank 60. Hereinafter, the fluid (e.g., hot water or cooling water) supplied to the temperature regulator 110 will also be referred to as a low-temperature fluid. The fluid (for example, hot water) supplied to the temperature regulator 120 is also called a high-temperature fluid.

[0029] That is, the treatment system 1000 of this embodiment can, for example, heat the excess sludge supplied from the storage tank 130 via the line L2 in stages in each of the temperature regulator 110 and the temperature regulator 120. Therefore, the treatment system 1000 of this embodiment can, for example, heat the excess sludge with a low-temperature fluid in the temperature regulator 110, and then heat the excess sludge with a high-temperature fluid in the temperature regulator 120. Therefore, the treatment system 1000 of this embodiment can sufficiently heat the excess sludge supplied to the digestion tank 60, even if, for example, a sufficient amount of high-temperature fluid cannot be secured. Furthermore, the treatment system 1000 of this embodiment can, for example, effectively utilize a low-temperature fluid.

[0030] As a result, the treatment system 1000 of this embodiment can, for example, accurately adjust the temperature of the digested sludge in the digestion tank 60 regardless of the amount of high-temperature fluid that can be supplied to the temperature regulator 120, and can accurately control the temperature of the digested sludge in the digestion tank 60 to maintain it at an appropriate temperature. Therefore, the treatment system 1000 of this embodiment can, for example, suppress a decrease in the digestion rate in the digestion tank 60.

[0031] [Control device 200 in the first embodiment] Next, the control device 200 in the first embodiment will be described. Fig. 3 is a diagram illustrating the hardware configuration of the control device 200 in the first embodiment. Fig. 4 is a diagram illustrating the function of the control device 200 in the first embodiment.

[0032] The control device 200 performs, for example, control of the temperature of at least one of the excess sludge and the digested sludge supplied to the digestion tank 60 (hereinafter also referred to as temperature adjustment control).

[0033] Specifically, the control device 200 is, for example, an electronic device having an electronic circuit, as shown in Fig. 3. More specifically, the control device 200 is, for example, a computer device having a CPU 201 which is a processor, a memory 202, a communication device 203, and a storage medium 204. Each unit is connected to each other, for example, via a bus 205.

[0034] The storage medium 204 has, for example, a program storage area (not shown) that stores a program 210 for performing temperature adjustment control. The storage medium 204 also has, for example, an information storage area 230 that stores information used when performing temperature adjustment control. The storage medium 204 may be, for example, a hard disk drive (HDD) or a solid state drive (SSD).

[0035] The CPU 201 performs temperature adjustment control by executing a program 210 loaded into the memory 202 from the storage medium 204, for example.

[0036] The communication device 203 accesses an operation terminal (not shown) through which an operator inputs necessary information, for example, via a network (not shown) such as the Internet.

[0037] 4, the control device 200 acquires the temperature (i.e., the temperature of the digested sludge in the digestion tank 60) measured by, for example, a thermometer T1 attached to the digestion tank 60. Thereafter, the control device 200 performs temperature adjustment control, for example, by using the acquired temperature.

[0038] The electronic circuitry of the control device 200 may be, for example, a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The temperature adjustment control may be performed by, for example, the FPGA or the ASIC.

[0039] [Temperature Control Process in the First Embodiment] Next, the temperature control process in the first embodiment will be described. Fig. 5 is a flowchart illustrating the temperature control process in the first embodiment. Note that the following description will be given assuming that the temperature adjustment control is performed automatically by the control device 200, but is not limited to this. Specifically, the temperature adjustment control may be performed manually by an operator, for example.

[0040] The control device 200 waits, for example, until it is time to execute temperature adjustment control (hereinafter also referred to as control execution time). The control execution time may be a regular time such as every minute.

[0041] Then, for example, when the control execution time arrives, the control device 200 acquires the temperature (the temperature of the digested sludge in the digestion tank 60) measured by the thermometer T1 (step S1 in FIG. 5).

[0042] Next, the control device 200 determines whether or not the temperature acquired in step S1 satisfies a predetermined condition (hereinafter also simply referred to as the predetermined condition) (step S2 in FIG. 5).

[0043] Note that, although the following description will be given assuming that the control device 200 performs control from step S2 onward by using the temperature measured by the thermometer T1, the present invention is not limited to this. Specifically, the control device 200 may perform control from step S2 onward by using, for example, a temperature measured by another thermometer. Specifically, the control device 200 may perform control from step S2 onward by using, for example, a temperature measured by a thermometer (not shown) provided on line L6 (the temperature of the excess sludge before it is supplied to the digestion tank 60).

[0044] As a result, for example, if it is determined that the temperature acquired in step S1 satisfies a predetermined condition (YES in step S2 in FIG. 5), the control device 200 adjusts the temperature of the digested sludge in the digestion tank 60 (step S3 in FIG. 5).

[0045] On the other hand, for example, if it is determined that the temperature acquired in step S1 does not satisfy the predetermined condition (NO in step S2 in FIG. 5), the control device 200 does not perform step S3.

[0046] Specifically, as shown in FIG. 2, when controlling the temperature of excess sludge supplied from storage tank 130 via line L2 (heating the excess sludge), the control device 200 controls to open valve V1 located downstream of pump P1 on line L2 and upstream of the junction with line L6, controls to open valve V2 located downstream of the branch point of line L2 to line L5 and upstream of temperature regulator 120, controls to close valve V3 located on line L5, and controls to close valve V4 located downstream of pump P2 on line L6 and upstream of the junction with line L2.

[0047] Then, for example, if it is determined that the temperature acquired in step S1 is below a predetermined lower threshold (hereinafter also referred to as the first lower threshold), the control device 200 determines that a predetermined condition is satisfied and performs control to increase the amount of fluid (high-temperature fluid) supplied to the temperature regulator 120 via line L4.

[0048] That is, for example, if the control device 200 determines that the temperature acquired in step S1 is below the first lower threshold, it increases the heating temperature of the excess sludge by the temperature regulator 120, thereby increasing the temperature of the digested sludge in the digestion tank 60.

[0049] Note that, although the following description is based on a case where a valve V1 is provided in line L2 and the control device 200 controls the opening and closing of the valve V1, the present invention is not limited to this. Specifically, for example, if a check valve (not shown) is provided in line L2 downstream of pump P1 and upstream of the junction with line L6, the valve V1 may not be provided in line L2. Also, the following description is based on a case where a valve V4 is provided in line L6 and the control device 200 controls the opening and closing of the valve V4, the present invention is not limited to this. Specifically, for example, if a check valve (not shown) is provided in line L6 downstream of pump P2 and upstream of the junction with line L2, the valve V4 may not be provided in line L6.

[0050] On the other hand, for example, if it is determined that the temperature acquired in step S1 exceeds a predetermined upper limit threshold (hereinafter also referred to as the first upper limit threshold), the control device 200 performs control to reduce the amount of fluid supplied to the temperature regulator 120 via line L4.

[0051] That is, for example, if the control device 200 determines that the temperature acquired in step S1 exceeds the first upper limit threshold, it lowers the temperature of the digested sludge in the digestion tank 60 by lowering the heating temperature of the excess sludge by the temperature regulator 120.

[0052] In addition, when the control device 200 adjusts the temperature of the digested sludge supplied from the digestion tank 60 via lines L6 and L2 (heating or cooling the digested sludge), it controls to close valve V1, open valve V2, close valve V3, and open valve V4.

[0053] Then, for example, when it is determined that the temperature acquired in step S1 is below a predetermined lower threshold (hereinafter also referred to as a second lower threshold), the control device 200 determines that a predetermined condition is satisfied and performs control to increase the amount of fluid supplied to the temperature regulator 120 via line L4. The second lower threshold may be, for example, a value different from or the same as the first lower threshold.

[0054] That is, for example, if the control device 200 determines that the temperature acquired in step S1 is below the second lower threshold, it increases the heating temperature of the digested sludge by the temperature regulator 120, thereby increasing the temperature of the digested sludge in the digestion tank 60.

[0055] On the other hand, for example, if it is determined that the temperature acquired in step S1 exceeds a predetermined upper limit threshold (hereinafter also referred to as a second upper limit threshold), the control device 200 performs control to reduce the amount of fluid supplied to the temperature regulator 120 via line L4. The second upper limit threshold may be, for example, a value different from or the same as the first upper limit threshold.

[0056] That is, for example, if the control device 200 determines that the temperature acquired in step S1 exceeds the second upper limit threshold, it lowers the temperature of the digested sludge in the digestion tank 60 by reducing the heating temperature of the digested sludge by the temperature regulator 120.

[0057] In addition, when controlling the temperature of digested sludge supplied from the digestion tank 60 via lines L6 and L2 (heating or cooling the digested sludge), the control device 200 may perform control to close valve V1, control to close valve V2, control to open valve V3, and control to open valve V4, for example.

[0058] For example, if the fluid supplied to the temperature regulator 110 via line L3 is hot water and it is determined that the temperature acquired in step S1 is below the second lower threshold, the control device 200 may determine that a predetermined condition is satisfied and perform control to increase the amount of fluid supplied to the temperature regulator 110 via line L3.

[0059] Furthermore, for example, if the fluid supplied to the temperature regulator 110 via line L3 is cooling water and it is determined that the temperature acquired in step S1 is below the second lower threshold, the control device 200 may determine that a predetermined condition is satisfied and perform control so that the fluid supplied to the temperature regulator 110 via line L3 is changed to hot water.

[0060] That is, for example, when the control device 200 determines that the temperature acquired in step S1 is below the second lower threshold, it may increase the temperature of the digested sludge in the digestion tank 60 by heating the digested sludge in the temperature regulator 110, while bypassing the temperature regulator 120 to prevent excessive heating of the digested sludge.

[0061] On the other hand, for example, if the fluid supplied to the temperature regulator 110 via line L3 is cooling water and it is determined that the temperature acquired in step S1 exceeds the second upper limit threshold, the control device 200 may determine that a predetermined condition is satisfied and perform control to increase the amount of fluid supplied to the temperature regulator 110 via line L3.

[0062] Furthermore, for example, if the fluid supplied to the temperature regulator 110 via line L3 is hot water and it is determined that the temperature acquired in step S1 exceeds the second upper limit threshold, the control device 200 may determine that a predetermined condition is satisfied and perform control so that the fluid supplied to the temperature regulator 110 via line L3 is changed to cooling water.

[0063] That is, for example, if the control device 200 determines that the temperature acquired in step S1 exceeds the second upper limit threshold, the control device 200 may lower the temperature of the digested sludge in the digestion tank 60 by cooling the digested sludge in the temperature regulator 110.

[0064] Thus, the treatment system 1000 of this embodiment includes, for example, a digestion tank 60 (hereinafter also referred to as the first tank) in which sludge is digested, a line L2 for supplying excess sludge to the digestion tank 60, a line L6 for circulating the digested sludge in the digestion tank 60 together with line L2 between the digestion tank 60 and the outside, a temperature regulator 110 (hereinafter also referred to as the first temperature regulator) for heating at least one of the excess sludge in line L2 and the digested sludge in line L6 with a fluid (hereinafter also referred to as the first fluid), and a temperature regulator 120 (hereinafter also referred to as the second temperature regulator) for heating at least one of the excess sludge and the digested sludge heated in the temperature regulator 110 with a fluid (hereinafter also referred to as the second fluid). The second fluid is, for example, a fluid with a higher temperature than the first fluid. Furthermore, the treatment system 1000 in this embodiment includes a control device 200 that controls, based on a temperature related to digestion, at least one of the heating of excess sludge in line L2 by the temperature regulator 110, the heating of digested sludge in line L2 by the temperature regulator 120, and the heating of excess sludge in line L2 by the temperature regulator 120. The temperature related to digestion is, for example, a temperature related to digestion, such as the temperature in the digestion tank 60, the temperature of the digested sludge itself, or the temperature of the excess sludge itself.

[0065] Specifically, in the treatment system 1000 of this embodiment, the control device 200 controls, for example, based on the temperature in the digestion tank 60, so that a fluid (hereinafter also referred to as a third fluid) having a lower temperature than the first fluid is supplied to the temperature regulator 110. Then, in the treatment system 1000 of this embodiment, the temperature regulator 110 cools, for example, the digested sludge in the line L2 using the third fluid.

[0066] The treatment system 1000 of this embodiment also includes, for example, a line L5 that communicates with the line L2 and bypasses the temperature regulator 120. In the treatment system 1000 of this embodiment, the control device 200 controls the supply of digested sludge to the line L5 based on, for example, the temperature in the digestion tank 60.

[0067] That is, the treatment system 1000 in this embodiment can, for example, heat the excess sludge supplied from the storage tank 130 via the line L2 in stages in each of the temperature regulator 110 and the temperature regulator 120. Therefore, the treatment system 1000 in this embodiment can, for example, heat the excess sludge with a low-temperature fluid in the temperature regulator 110, and then heat the excess sludge with a high-temperature fluid in the temperature regulator 120. Therefore, the treatment system 1000 in this embodiment can sufficiently heat the excess sludge supplied to the digestion tank 60, even if, for example, a sufficient amount of high-temperature fluid cannot be secured.

[0068] As a result, the treatment system 1000 of this embodiment can, for example, accurately adjust the temperature of the digested sludge in the digestion tank 60 regardless of the amount of high-temperature fluid that can be supplied to the temperature regulator 120, and can accurately control the temperature of the digested sludge in the digestion tank 60 to maintain it at an appropriate temperature. Therefore, the treatment system 1000 of this embodiment can, for example, suppress a decrease in the digestion rate in the digestion tank 60.

[0069] Furthermore, the treatment system 1000 in this embodiment is capable of, for example, heating or cooling the digested sludge in the digestion tank 60 (digested sludge supplied from the digestion tank 60 via line L6 and line L2) in the temperature regulator 110, or in each of the temperature regulators 110 and 120.

[0070] As a result, the treatment system 1000 of this embodiment can, for example, more accurately adjust the temperature of the digested sludge in the digestion tank 60, and can more accurately control the temperature of the digested sludge to be maintained at an appropriate temperature in the digestion tank 60. Therefore, the treatment system 1000 of this embodiment can, for example, more effectively suppress a decrease in the digestion rate in the digestion tank 60.

[0071] [Temperature Adjustment System 100 in Modification] Next, a temperature adjustment system 100 in a modified example will be described. Fig. 6 is a diagram illustrating the configuration of a temperature adjustment system 100 in a modified example. Below, differences from the temperature adjustment system 100 in the first embodiment will be described.

[0072] As shown in FIG. 6, the temperature adjustment system 100 in this modified example has, for example, a storage tank 140 and a pump P3 in addition to the components of the temperature adjustment system 100 in the first embodiment.

[0073] As shown in Figure 6, the temperature control system 100 in this modified example has, for example, instead of line L2, a line L2a that sequentially connects the storage tank 130, the temperature regulator 110, and the storage tank 140, and a line L2b that sequentially connects the storage tank 140, the temperature regulator 120, and the digestion tank 60.

[0074] The storage tank 140 is a tank that stores at least one of excess sludge and digested sludge supplied from the temperature regulator 110 via the line L2a, for example.

[0075] Pump P3 is provided, for example, on line L2b, and supplies at least one of excess sludge and digested sludge supplied from storage tank 140 to temperature regulator 120, and further supplies at least one of excess sludge and digested sludge heated by temperature regulator 120 to digestion tank 60.

[0076] Furthermore, the line L2a is provided with a line L7 that connects, for example, a position between the temperature regulator 110 and the storage tank 140 to the storage tank 130. Hereinafter, the line L7 will also be referred to as a third pipe.

[0077] Furthermore, line L2b is provided with, for example, line L8 that connects a position between temperature regulator 120 and digester tank 60 to storage tank 140. Hereinafter, line L8 will also be referred to as fourth piping.

[0078] For example, when adjusting the temperature of excess sludge supplied from the storage tank 130 via line L2a (heating the excess sludge), the control device 200 controls to open valve V1 located on line L2a downstream of pump P1 and upstream of the junction with line L6, controls to open valve V2 located on line L2a downstream of the branch point of line L5 and upstream of the temperature regulator 120, controls to open valve V7 located on line L2b downstream of the branch point of line L8 and upstream of the digestion tank 60, controls to close valve V3 located on line L5, controls to close valve V4 located on line L6 downstream of pump P2 and upstream of the junction with line L2a, controls to close valve V5 located on line L7, and controls to close valve V6 located on line L8.

[0079] Here, for example, if it is determined that the temperature measured by a thermometer T2 installed downstream of the temperature regulator 110 on the line L2a and upstream of the storage tank 140 is below a predetermined threshold value (hereinafter also referred to as the first threshold value), the control device 200 controls to close valve V2 and to open valve V5, and controls to supply (return) the excess sludge supplied from the temperature regulator 110 to the storage tank 130.

[0080] In other words, in this case, the control device 200 repeatedly circulates the excess sludge between the storage tank 130 and the temperature regulator 110 and repeatedly heats the excess sludge using the temperature regulator 110, for example, until the temperature of the excess sludge supplied from the temperature regulator 110 becomes equal to or higher than the first threshold value.

[0081] This enables the control device 200 to, for example, control the temperature of the excess sludge supplied to the storage tank 140 so that it becomes equal to a first threshold value, thereby stabilizing the temperature of the excess sludge supplied to the storage tank 140.

[0082] In addition, the control device 200 may, for example, control the supply (return) of excess sludge supplied from the temperature regulator 110 to the storage tank 130 when it determines that the liquid level (liquid level of excess sludge in the storage tank 130) measured by a liquid level meter (not shown) installed in the storage tank 130 is below a predetermined threshold value.

[0083] Furthermore, for example, if it is determined that the temperature measured by a thermometer T3 installed downstream of the temperature regulator 120 on line L2b and upstream of the digestion tank 60 is below a predetermined threshold (hereinafter also referred to as the second threshold), the control device 200 controls to close valve V7 and to open valve V6, thereby controlling to supply (return) the excess sludge supplied from the temperature regulator 120 to the storage tank 140.

[0084] In other words, in this case, the control device 200 repeatedly circulates the excess sludge between the storage tank 140 and the temperature regulator 120 and repeatedly heats the excess sludge using the temperature regulator 120, for example, until the temperature of the excess sludge supplied from the temperature regulator 120 becomes equal to or higher than the second threshold value.

[0085] This enables the control device 200 to, for example, control the temperature of the excess sludge supplied to the digestion tank 60 so that it becomes equal to the second threshold value, thereby stabilizing the temperature of the excess sludge supplied to the digestion tank 60.

[0086] In addition, the control device 200 may, for example, control the supply (return) of excess sludge supplied from the temperature regulator 120 to the storage tank 140 when it determines that the liquid level (liquid level of excess sludge in the storage tank 140) measured by a liquid level meter (not shown) installed in the storage tank 140 is below a predetermined threshold value.

[0087] Thus, the treatment system 1000 in this modified example includes, for example, a storage tank 130 (hereinafter also referred to as the second tank) that stores excess sludge supplied to the temperature regulator 110, and a line L7 that communicates with line L2a and supplies excess sludge heated in the temperature regulator 110 to the storage tank 130. In the treatment system 1000 in this modified example, the control device 200 controls the supply of excess sludge to line L7 based on, for example, at least one of the temperature of the excess sludge heated in the temperature regulator 110 and the liquid level of the excess sludge in the storage tank 130.

[0088] Furthermore, the treatment system 1000 in this modified example includes, for example, a storage tank 140 (hereinafter also referred to as a third tank) that stores at least one of excess sludge and digested sludge supplied from the temperature regulator 110. In the treatment system 1000 in this modified example, the temperature regulator 120 heats at least one of the excess sludge and digested sludge supplied from the storage tank 140 with a second fluid.

[0089] Furthermore, the treatment system 1000 in this modified example includes, for example, a line L8 that communicates with the line L2b and supplies the excess sludge that has been heated in the temperature regulator 120 to the storage tank 140. In the treatment system 1000 in this modified example, the control device 200 controls the supply of excess sludge to the line L8 based on, for example, at least one of the temperature of the excess sludge that has been heated in the temperature regulator 120 and the liquid level of the excess sludge in the storage tank 140.

[0090] That is, the treatment system 1000 in this modified example can stabilize the temperature of the excess sludge supplied to the digestion tank 60, for example.

[0091] This allows the treatment system 1000 of this modified example to, for example, more accurately adjust the temperature of the digested sludge in the digestion tank 60. Therefore, the treatment system 1000 of this modified example can, for example, more accurately control the temperature of the digested sludge in the digestion tank 60 to be maintained at an appropriate temperature. Therefore, the treatment system 1000 of this modified example can, for example, more accurately suppress a decrease in the digestion rate in the digestion tank 60.

[0092] Furthermore, the treatment system 1000 in this modification, for example, by including the storage tank 140 and the pump P3, can supply excess sludge supplied to the storage tank 140 to the digestion tank 60 while releasing the pressure in the line L2a in the storage tank 140. Therefore, the treatment system 1000 in this modification can, for example, reduce the supply pressure of excess sludge by the pump P1, and can suppress the pressure in the temperature regulator 110. Therefore, the treatment system 1000 in this modification can, for example, suppress the occurrence of a malfunction in the temperature regulator 110. Furthermore, the treatment system 1000 in this modification can, for example, achieve a reduction in the size of the pump P1 and suppress the power consumption of the pump P1.

[0093] In the treatment system 1000 in the first embodiment and the modified example, for example, the amount of excess sludge and digested sludge supplied to the temperature regulator 110 and the temperature regulator 120 is adjusted by controlling the opening and closing of valves V1, V2, V3, V4, V5, V6, and V7, but this is not limited to this. Specifically, in the treatment system 1000 in the first embodiment and the modified example, for example, the amount of excess sludge and digested sludge supplied to the temperature regulator 110 and the temperature regulator 120 may be adjusted by controlling the rotation speed of pumps P1, P2, and P3, etc. [Explanation of symbols]

[0094] 10: Primary sedimentation tank 20: Reaction tank 30: Final sedimentation tank 40: Thickener 50: Concentrator 60: Digestion tank 100: Temperature control system 110: Temperature controller 120: Temperature regulator 130: Storage tank 140: Storage tank 200: Control device 201:CPU 202:Memory 203: Communication device 204: Storage medium 205: Bus 210: Program 230: Information storage area 1000: Processing system L1: Line L2: Line L2a: Line L2b: Line L3: Line L4: Line L5: Line L6: Line L7: Line L8: Line P1: Pump P2: Pump P3: Pump T1: Thermometer T2: Thermometer T3: Thermometer V1: Valve V2: Valve V3: Valve V4: Valve V5: Valve V6: Valve V7: Valve

Claims

1. a first tank for digesting sludge; a first pipe for supplying excess sludge to the first tank; a second pipe for circulating the digested sludge in the first tank between the first tank and the outside; a first temperature regulator that heats at least one of the excess sludge in the first pipe and the digested sludge in the second pipe with a first fluid; a second temperature regulator that heats, by a second fluid, at least one of the excess sludge and the digested sludge that have been heated in the first temperature regulator; A digestion system comprising: a control device that controls, based on the temperature related to the digestion, at least one of the heating of the excess sludge in the first pipe by the first temperature regulator, the heating of the digested sludge in the second pipe by the first temperature regulator, the heating of the excess sludge in the first pipe by the second temperature regulator, and the heating of the digested sludge in the second pipe by the second temperature regulator.

2. the control device controls, based on the temperature related to the extinguishing, a third fluid having a temperature lower than that of the first fluid to be supplied to the first temperature regulator; The digestion system according to claim 1 , wherein the first temperature regulator cools the digested sludge in the second pipe by the third fluid.

3. The first piping has a part of the piping in common with the second piping, the first temperature regulator and the second temperature regulator are each provided in the partial pipe; further comprising a bypass pipe communicating with the partial pipe and bypassing the second temperature regulator, The digestion system according to claim 1 , wherein the control device controls the supply of the digested sludge to the bypass pipe based on the temperature in the first tank.

4. The first piping has a part of the piping in common with the second piping, the first temperature regulator and the second temperature regulator are each provided in the partial pipe; a second tank for storing the excess sludge supplied to the first temperature regulator; a third pipe that communicates with the partial pipe between the first temperature regulator and the second temperature regulator and supplies the excess sludge that has been heated in the first temperature regulator to the second tank; The digestion system described in claim 1, wherein the control device controls the supply of the excess sludge to the third piping based on at least one of the temperature of the excess sludge heated in the first temperature regulator and the liquid level of the excess sludge in the second tank.

5. further comprising a third tank for storing at least one of the excess sludge and the digested sludge supplied from the first temperature regulator; The digestion system according to claim 1 , wherein the second temperature regulator heats at least one of the excess sludge and the digested sludge supplied from the third tank with the second fluid.

6. The first piping has a part of the piping in common with the second piping, the first temperature regulator and the second temperature regulator are each provided in the partial pipe; a fourth pipe connected to the partial pipe between the second temperature regulator and the first tank, for supplying the excess sludge heated in the second temperature regulator to the third tank; The digestion system described in claim 5, wherein the control device controls the supply of at least one of the excess sludge and the digested sludge to the fourth piping based on at least one of the temperature of the excess sludge heated in the second temperature regulator and the liquid level of the excess sludge in the third tank.

7. A heating control method for a digestion system comprising: a first tank for digesting sludge; a first pipe for supplying excess sludge to the first tank; a second pipe for circulating the digested sludge in the first tank between the first tank and an outside thereof; a first temperature regulator for heating at least one of the excess sludge in the first pipe and the digested sludge in the second pipe with a first fluid; and a second temperature regulator for heating at least one of the excess sludge and the digested sludge heated in the first temperature regulator with a second fluid, A heating control method that controls at least one of heating of at least one of the excess sludge and the digested sludge by the first temperature regulator and heating of at least one of the excess sludge and the digested sludge by the second temperature regulator based on the temperature related to the digestion.

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