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 digestion system comprises: a tank that performs digestion of sludge; a first pipe that supplies excess sludge to the tank; a second pipe that circulates digested sludge between inside and outside of the tank; a first heater that heats the excess sludge in the first pipe with a first fluid; a second heater that heats the digested sludge in the second pipe with a second fluid; a heat-source system including a plurality of heat-source devices capable of heating each of the first fluid and the second fluid; and a control device that, based on a temperature related to digestion, controls at least one of heating of the excess sludge in the first pipe by the first heater and heating of the digested sludge in the second pipe by the second heater by controlling the heat-source system.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 tank for digesting sludge, a first pipe for supplying excess sludge to the tank, a second pipe for circulating the digested sludge in the tank between the tank and the outside, a first heater for heating the excess sludge in the first pipe with a first fluid, a second heater for heating the digested sludge in the second pipe with a second fluid, a heat source system including a plurality of heat source devices capable of heating each of the first fluid and the second fluid, and a control device for controlling the heat source system based on the temperature related to the digestion, thereby controlling at least one of the heating of the excess sludge in the first pipe by the first heater and the heating of the digested sludge in the second pipe by the second heater. [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 configuration of the heat source system 120 according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the hardware configuration of the control device 200 in the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating the function of the control device 200 in the first embodiment. [Figure 6] FIG. 6 is a flowchart illustrating the temperature control process in the first embodiment. [Figure 7] FIG. 7 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 according to 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 releases 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 excess sludge discharged from, for example, 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 heater 110 (hereinafter also referred to as the first heater 110), a heat source system 120, a heater 130 (hereinafter also referred to as the second heater 130), a pump P1, a pump P2, a pump P3, a pump P4, and a pump P5.

[0022] Pump P1 is provided, for example, in line L1, and supplies excess sludge from the thickener 50 to the heater 110, and further supplies the excess sludge heated by the heater 110 to the digester 60. Line L1 is, for example, a pipe that sequentially connects the thickener 50, the heater 110, and the digester 60. Hereinafter, line L1 will also be referred to as the first pipe.

[0023] The pump P2 is provided, for example, in the line L2, and circulates a fluid (for example, a fluid such as hot water) between the heater 110 and the heat source system 120. The line L2 is, for example, a circulation pipe that connects the heater 110 and the heat source system 120.

[0024] The heater 110 heats excess sludge (excess sludge before being supplied to the digestion tank 60) supplied from the thickener 50 via, for example, line L1. Specifically, the heater 110 is, for example, a heat exchanger that heats the excess sludge using a fluid circulating through line L2. The excess sludge heated by the heater 110 is then supplied to the digestion tank 60 via, for example, line L1.

[0025] The heat source system 120 includes, for example, a plurality of heat source devices 121 each capable of heating a fluid supplied from the heater 110 via a line L1.

[0026] That is, one of the causes of the decrease in digestion rate in the digestion tank 60 is, for example, the large amount of bacteria (hereinafter simply referred to as bacteria) living in the excess sludge. If the excess sludge containing bacteria is supplied as is to the digestion tank 60, the anaerobic bacteria (digestion bacteria) in the digestion tank 60 may not be able to sufficiently decompose (digest) the bacteria, for example.

[0027] Therefore, the temperature adjustment system 100 in this embodiment sufficiently kills the viable bacteria contained in the excess sludge by, for example, intensively heating the excess sludge using the heater 110 before the excess sludge is supplied to the digestion tank 60. Then, the temperature adjustment system 100 maintains the temperature of the digested sludge in the digestion tank 60 at an appropriate temperature by, for example, using the heated excess sludge as a heat medium.

[0028] As a result, the treatment system 1000 in this embodiment can suppress a decrease in the digestion rate in the digestion tank 60, for example.

[0029] Returning to Figure 2, pump P3 is provided, for example, in line L3, and supplies primary sludge supplied from the thickener 40 to line L1. Line L3 is, for example, a pipe connecting the thickener 40 and line L1 (a position on line L1 between the heater 110 and the digester 60). Hereinafter, line L3 will also be referred to as the third pipe.

[0030] That is, pump P3 cools the excess sludge (excess sludge after being heated by heater 110) before it is supplied to digestion tank 60, for example, by appropriately supplying primary settling sludge to the excess sludge in line L1.

[0031] As a result, the treatment system 1000 of this embodiment can, for example, bring the temperature of the excess sludge heated by the heater 110 closer to the temperature of the digested sludge in the digestion tank 60. Therefore, the treatment system 1000 of this embodiment can, for example, suppress a decrease in the activity of anaerobic bacteria (digestion bacteria) in the digestion tank 60 due to the supply of excess sludge to the digestion tank 60 (i.e., the supply of high-temperature excess sludge). Therefore, the treatment system 1000 of this embodiment can further suppress a decrease in the digestion rate in the digestion tank 60, for example.

[0032] Line L3 may be, for example, a pipe that communicates with digestion tank 60. The primary sludge supplied from thickener 40 may be supplied directly to digestion tank 60, for example.

[0033] Returning to Figure 2, pump P4 is provided, for example, in line L5, and circulates a fluid (e.g., a fluid such as hot water) between the heater 130 and the digestion tank 60. Line L5 is, for example, a circulation pipe that connects the heater 130 and the digestion tank 60. Hereinafter, line L5 will also be referred to as a second pipe.

[0034] The pump P5 is provided, for example, in the line L6, and circulates a fluid (for example, a fluid such as hot water) between the heater 130 and the heat source system 120. The line L6 is, for example, a circulation pipe that communicates between the heater 130 and the heat source system 120.

[0035] The heater 130 heats the digested sludge supplied from the digestion tank 60 via, for example, line L5. Specifically, the heater 130 is, for example, a heat exchanger that heats the digested sludge using a fluid circulating through line L6. The excess sludge heated by the heater 130 is then supplied back to the digestion tank 60 via, for example, line L5.

[0036] The heat source system 120 (plurality of heat source devices 121) heats the fluid supplied from the heater 130 via, for example, a line L6.

[0037] That is, the heat source system 120 (multiple heat source devices 121) not only heats the fluid (fluid that heats excess sludge) supplied from the heater 110 via line L1, but also heats the fluid (fluid that heats digested sludge) supplied from the heater 130 via line L6.

[0038] As a result, the treatment system 1000 of this embodiment can maintain the temperature of the digested sludge in the digestion tank 60 at an appropriate temperature by heating the digested sludge supplied from the digestion tank 60, even if the temperature in the digestion tank 60 cannot be adequately adjusted by heating the excess sludge supplied to the digestion tank 60. Therefore, the treatment system 1000 of this embodiment can suppress a decrease in the digestion rate in the digestion tank 60, even if the temperature in the digestion tank 60 cannot be adequately adjusted by heating the excess sludge supplied to the digestion tank 60.

[0039] Furthermore, in the treatment system 1000 of this embodiment, for example, the heating of the fluid that heats the excess sludge and the heating of the fluid that heats the digested sludge are performed in the same system (heat source system 120), thereby making it possible to reduce the number of devices required to maintain the temperature of the digested sludge at an appropriate temperature in the digestion tank 60. Therefore, in the treatment system 1000 of this embodiment, it is possible to reduce the costs required for installing and maintaining each device, for example.

[0040] [Heat Source System 120 in the First Embodiment] Next, the heat source system 120 according to the first embodiment will be described. Fig. 3 is a diagram illustrating the configuration of the heat source system 120 according to the first embodiment.

[0041] 3, the multiple heat source devices 121 include, for example, a heat exchanger 121a that heats a fluid with waste heat from exhaust gas generated in an incinerator (not shown) that incinerates the digested sludge discharged from the digester tank 60. The multiple heat source devices 121 also include, for example, a heat exchanger 121b that heats a fluid with waste heat generated in conjunction with power generation (power generation in a generator) using the digester gas discharged from the digester tank 60. The multiple heat source devices 121 also include, for example, a water heater 121c that heats a fluid with the digester gas discharged from the digester tank 60. Note that the multiple heat sources described above are merely examples, and various heat sources can be used.

[0042] 3, the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c are connected to each other via, for example, a line L11. The line L11 is, for example, a pipe that connects the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c to each other.

[0043] The fluid supplied from the heater 110 via the line L2 (the fluid circulating through the line L2) is heated by being supplied to, for example, at least one of the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c. Specifically, the fluid supplied from the heater 110 via the line L2 is heated by being supplied to, for example, the heat source device 121 that is not heating the fluid supplied from the heater 130, among the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c.

[0044] Furthermore, the fluid supplied from the heater 130 via the line L6 (the fluid circulating through the line L6) is heated by being supplied to, for example, at least one of the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c. Specifically, the fluid supplied from the heater 130 via the line L6 is heated by being supplied to, for example, the heat source device 121 that is not heating the fluid supplied from the heater 110, among the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c.

[0045] Note that, although the following description will be given of a case where the heat source system 120 has three heat source devices 121 (heat exchanger 121a, heat exchanger 121b, and water heater 121c), the present invention is not limited to this. Specifically, the heat source system 120 may have, for example, two or four or more heat source devices 121.

[0046] [Control device 200 in the first embodiment] Next, the control device 200 in the first embodiment will be described. Fig. 4 is a diagram illustrating the hardware configuration of the control device 200 in the first embodiment. Fig. 5 is a diagram illustrating the function of the control device 200 in the first embodiment.

[0047] The control device 200 performs control (hereinafter also referred to as temperature adjustment control) of at least one of, for example, adjusting the temperature of excess sludge supplied to the digestion tank 60 and adjusting the temperature of digested sludge in the digestion tank 60.

[0048] Specifically, the control device 200 is, for example, an electronic device having an electronic circuit, as shown in Fig. 4. 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.

[0049] 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).

[0050] The CPU 201 performs temperature adjustment control by executing a program 210 loaded into the memory 202 from the storage medium 204, for example.

[0051] 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.

[0052] Then, 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 T attached to the digestion tank 60, as shown in Figure 5. Thereafter, the control device 200 performs temperature adjustment control, for example, by using the acquired temperature.

[0053] 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.

[0054] [Temperature Control Process in the First Embodiment] Next, the temperature control process in the first embodiment will be described. Fig. 6 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.

[0055] 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.

[0056] Then, for example, when the control execution time arrives, the control device 200 acquires the temperature measured by the thermometer T (the temperature of the digested sludge in the digestion tank 60) (step S1 in FIG. 6).

[0057] 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. 6).

[0058] Note that, although the following description will be given assuming that the control device 200 performs control from step S2 onwards by using the temperature measured by the thermometer T, the present invention is not limited to this. Specifically, the control device 200 may perform control from step S2 onwards by using, for example, a temperature measured by another thermometer. Specifically, the control device 200 may perform control from step S2 onwards by using, for example, a temperature measured by a thermometer (not shown) provided on the line L1 (the temperature of the excess sludge before it is supplied to the digestion tank 60).

[0059] 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. 6), the control device 200 adjusts the temperature of the digested sludge in the digestion tank 60 (step S3 in FIG. 6).

[0060] 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. 6), the control device 200 does not perform step S3.

[0061] Specifically, for example, if it is determined that the temperature acquired in step S1 is below a predetermined lower threshold value (hereinafter simply referred to as the lower threshold value), the control device 200 determines that the specified conditions are met and heats the digested sludge using the heater 130.

[0062] More specifically, in this case, the control device 200 starts the supply of digested sludge to the heater 130 (circulation of digested sludge in line L5) by controlling pump P4 so that digested sludge is supplied from the digestion tank 60 to the heater 130, and starts heating the digested sludge in the digestion tank 60.

[0063] In this case, the control device 200 controls the heat source system 120, for example, to control the temperature of the fluid supplied from the heater 130 via the line L6 (the heating temperature of the excess sludge in the heater 130).

[0064] [Specific example of control in heat source system 120] Next, a specific example of control in the heat source system 120 will be described with reference to FIG.

[0065] For example, when heating the fluid supplied from the heater 130 via the line L6 by using the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c, the control device 200 controls the valves V41, V42, V43, V44, V45, and V46 provided on the line L11 to open, and controls the valves V51, V52, and V53 to close, thereby controlling the fluid supplied from the heater 130 via the line L6 to be supplied to the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c, respectively.

[0066] In this case, the control device 200 controls, for example, to close valves V11, V12, V13, V14, V15, V16, V21, V22, V23, V24, V31, V32, and V33 provided on line L11, thereby preventing the fluid supplied from the heater 110 via line L2 from being supplied to the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c.

[0067] Furthermore, when the control device 200 heats the fluid supplied from the heater 130 via the line L6 by using the heat exchanger 121a and the water heater 121c, respectively, it controls the valves V41, V42, V52, V45, and V46 provided on the line L11 to open, and controls the valves V43, V44, V51, and V53 to close, thereby controlling the fluid supplied from the heater 130 via the line L6 to be supplied to the heat exchanger 121a and the water heater 121c, respectively.

[0068] In this case, the control device 200 controls, for example, to open valves V21, V31, V22, V13, V14, V23, V33, and V24 provided on line L11, and controls to close valves V11, V12, V32, V15, and V16 provided on line L11, thereby controlling the fluid supplied from the heater 110 via line L2 to be supplied to the heat exchanger 121b.

[0069] Furthermore, when the control device 200 heats the fluid supplied from the heater 130 via the line L6 by using the heat exchanger 121a, for example, the control device 200 controls the valves V41, V42, V52, and V53 provided on the line L11 to open, and controls the valves V43, V44, V45, V46, and V51 to close, thereby controlling the fluid supplied from the heater 130 via the line L6 to be supplied to the heat exchanger 121a.

[0070] In this case, the control device 200 controls, for example, to open valves V21, V31, V22, V13, V14, V15, and V16 provided on line L11, and controls to close valves V11, V12, V23, V24, V32, and V33 provided on line L11, thereby controlling the fluid supplied from the heater 110 via line L2 to be supplied to each of the heat exchanger 121b and the hot water heater 121c.

[0071] Furthermore, when the control device 200 does not heat the fluid supplied from the heater 130 via the line L6, for example, it controls the valves V51, V52, and V53 provided on the line L11 to open, and controls the valves V41, V42, V43, V44, V45, and V46 to close, thereby preventing the fluid supplied from the heater 130 via the line L6 from being supplied to the heat exchanger 121a, the heat exchanger 121b, and the water heater 121c.

[0072] In this case, the control device 200 controls, for example, to open valves V11, V12, V13, V14, V15, and V16 provided on line L11, and to close valves V21, V22, V23, V24, V31, V32, and V33 provided on line L11, thereby controlling the fluid supplied from the heater 110 via line L2 to be supplied to each of the heat exchangers 121a, 121b, and the water heater 121c.

[0073] That is, the control device 200, for example, appropriately assigns each of the multiple heat source devices 121 to a heat source device 121 that heats the fluid supplied from the heater 110 via line L2 and a heat source device 121 that heats the fluid supplied from the heater 130 via line L6. Specifically, the control device 200, for example, identifies, from the multiple heat source devices 121, a heat source device 121 that is not being used to heat the fluid supplied from the heater 110. Then, the control device 200 uses, for example, at least one of the identified heat source devices 121 as the heat source device 121 that heats the fluid supplied from the heater 130. Furthermore, the control device 200, for example, identifies, from the multiple heat source devices 121, a heat source device 121 that is not being used to heat the fluid supplied from the heater 130. Then, the control device 200 uses, for example, at least one of the identified heat source devices 121 as the heat source device 121 that heats the fluid supplied from the heater 110.

[0074] As a result, the treatment system 1000 of this embodiment can, for example, accurately adjust the temperature of the excess sludge supplied to the digestion tank 60 and the temperature of the digested sludge in the digestion tank 60. Therefore, the treatment system 1000 of this embodiment can, for example, suppress a decrease in the digestion rate in the digestion tank 60.

[0075] Thus, the treatment system 1000 of this embodiment includes, for example, a digestion tank 60 for digesting sludge, a line L1 for supplying excess sludge to the digestion tank 60, a heater 110 for heating the excess sludge in line L1 with a fluid (hereinafter also referred to as a first fluid), a heater 130 for heating the excess sludge in line L5 with a fluid (hereinafter also referred to as a second fluid), and a heat source system 120 including a plurality of heat source devices 121 capable of heating each of the first fluid and the second fluid. The treatment system 1000 of this embodiment also includes a control device 200 that controls the heat source system 120 based on, for example, a temperature related to digestion, thereby controlling at least one of the heating of the excess sludge in line L1 by the heater 110 and the heating of the digested sludge in line L5 by the heater 130. 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.

[0076] Specifically, in the treatment system 1000 of this embodiment, for example, when the temperature in the digestion tank 60 is below a lower threshold, the control device 200 controls the heat source system 120 so that the second fluid is heated by at least one of the multiple heat source devices 121, thereby heating the digested sludge in line L5 by the heater 130.

[0077] Furthermore, in the treatment system 1000 of this embodiment, for example, when the temperature in the digestion tank 60 is below a lower limit threshold, the control device 200 identifies a heat source device 121 (hereinafter also referred to as a specific heat source device 121) that is not heating the first fluid among the multiple heat source devices 21. Then, the control device 200 controls the heat source system 120 so that the second fluid is heated by at least one of the specific heat source devices 121, thereby heating the digested sludge in the line L5 by the heater 130.

[0078] The treatment system 1000 in this embodiment also includes a line L3 that communicates with the heater 110 on the line L1 and the digestion tank 60, for example, and supplies primary sludge to the line L1.

[0079] As a result, the treatment system 1000 of this embodiment can, for example, maintain the temperature of the digested sludge at an appropriate temperature in the digestion tank 60. Therefore, the treatment system 1000 of this embodiment can, for example, suppress a decrease in the digestion rate in the digestion tank 60.

[0080] [Temperature Adjustment System 100 in Modification] Next, a temperature adjustment system 100 in a modified example will be described. Fig. 7 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.

[0081] The temperature adjustment system 100 in this modified example further includes a cooler 141, for example, as shown in FIG.

[0082] The cooler 141 is provided, for example, on the line L7 and cools the fluid supplied from the heat source system 120. The line L7 is, for example, a bypass pipe that bypasses the valve V1 provided on the line L6. Specifically, the cooler 141 is, for example, a cooling tower that cools the fluid supplied from the heat source system 120. The cooler 141 is also, for example, a heat exchanger that cools the fluid supplied from the heat source system 120 by exchanging heat between the fluid supplied from the heat source system 120 and another fluid (for example, treated water in the treatment system 1000) supplied from a refrigerant source device (not shown).

[0083] Then, for example, when the temperature measured by the thermometer T exceeds a predetermined upper threshold (hereinafter simply referred to as the upper threshold), the control device 200 controls to close the valve V1 provided on the line L6 and controls to open the valves V2 and V3 provided on the line L7, thereby supplying the fluid supplied from the heat source system 120 to the cooler 141 and cooling the fluid supplied to the heater 130. The upper threshold is, for example, a threshold greater than or equal to the lower threshold. Note that in this case, the control device 200 may, for example, control the fluid supplied to the heat source system 120 so that it is not supplied to each heat source device 121 in the heat source system 120. Hereinafter, the cooler 141, the line L7, the valve V2, and the valve V3 are collectively referred to as the cooling system 140.

[0084] That is, in this case, the control device 200 cools the digested sludge supplied from the digestion tank 60 in the heater 130, for example, by cooling the fluid supplied to the heater 130.

[0085] On the other hand, for example, when the temperature measured by the thermometer T does not exceed the upper threshold, the control device 200 controls the valve V1 to open and controls the valves V2 and V3 to close, thereby not supplying the fluid supplied from the heat source system 120 to the cooler 141.

[0086] In this way, the treatment system 1000 in this modification further includes, for example, a cooling system 140 capable of cooling the second fluid. Then, for example, when the temperature in the digestion tank 60 exceeds the upper threshold, the control device 200 controls the cooling system 140 to cool the second fluid, thereby cooling the digested sludge in the line L5 by the heater 130.

[0087] As a result, the treatment system 1000 in this modified example can, for example, not only heat the digested sludge in the digestion tank 60, but also cool the digested sludge in the digestion tank 60. Therefore, the treatment system 1000 in this modified example can, for example, more accurately adjust the temperature of the digested sludge in the digestion tank 60, and can maintain the temperature of the digested sludge in the digestion tank 60 at an appropriate temperature.

[0088] In addition, the treatment system 1000 in this modified example achieves temperature control in the digestion tank 60 by two systems (hereinafter simply referred to as two systems): a heating system (hereinafter simply referred to as the heating system) that heats sludge such as primary settling sludge and excess sludge that is fed into the digestion tank 60, and a temperature control system (hereinafter simply referred to as the temperature control system) that heats and cools the digested sludge circulating between inside and outside the digestion tank 60.

[0089] As a result, the treatment system 1000 in this modified example can perform temperature control of the digester 60 using two systems, for example, by adding equipment that handles a heating system to existing equipment that handles a temperature control system. Therefore, the treatment system 1000 in this modified example can easily perform temperature control of the digester 60 using two systems, and can reduce the costs required for performing temperature control of the digester 60 using two systems.

[0090] In the processing system 1000 according to the first embodiment and the modified example, for example, the amount of fluid supplied to each heat source device 121 can be adjusted by controlling the opening and closing of the valve V11, but this is not limiting. Specifically, in the processing system 1000 according to the first embodiment and the modified example, for example, the amount of fluid supplied to each heat source device 121 may be adjusted by controlling the rotation speed of the pump P2, etc.

[0091] In addition, in the processing system 1000 of the modified example, for example, the case where the amount of fluid supplied to the cooler 141 can be adjusted by controlling the opening and closing of the valve V1 or the like has been described, but this is not limiting. Specifically, in the processing system 1000 of the modified example, for example, the amount of fluid supplied to the cooler 141 may be adjusted by controlling the rotation speed of the pump P5 or the like. [Explanation of symbols]

[0092] 10: Primary sedimentation tank 20: Reaction tank 30: Final settling tank 40: Thickener 50: Concentrator 60: Digestion tank 100: Temperature control system 110: Heater 120: Heat source system 121: Heat source device 121a: Heat exchanger 121b: Heat exchanger 121c: Water heater 130: Heater 140: Cooling system 141: Cooler 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 L3: Line L5: Line L6: Line L7: Line L11: Line P1: Pump P2: Pump P3: Pump P4: Pump P5: Pump T: Thermometer V1: Valve V2: Valve V3: Valve V4: Valve V11: Valve V12: Valve V13: Valve V14: Valve V15: Valve V16: Valve V21: Valve V22: Valve V23: Valve V24: Valve V31: Valve V32: Valve V33: Valve V41: Valve V42: Valve V43: Valve V44: Valve V45: Valve V46: Valve V51: Valve V52: Valve V53: Valve

Claims

1. a tank for digesting sludge; a first pipe for supplying excess sludge to the tank; a second pipe for circulating the digested sludge in the tank between the tank and the outside; a first heater that heats the excess sludge in the first pipe with a first fluid; a second heater that heats the digested sludge in the second pipe with a second fluid; a heat source system including a plurality of heat source devices capable of heating the first fluid and the second fluid, respectively; A digestion system comprising: a control device that controls the heat source system based on the temperature related to the digestion, thereby controlling at least one of the heating of the excess sludge in the first pipe by the first heater and the heating of the digested sludge in the second pipe by the second heater.

2. The digestion system described in claim 1, wherein the control device controls the heat source system so that the second fluid is heated by at least one of the plurality of heat source devices when the temperature in the tank is below a lower threshold, thereby heating the digested sludge in the second piping by the second heater.

3. The control device If the temperature in the tank is below a lower limit threshold, identifying a specific heat source device among the plurality of heat source devices that is not heating the first fluid; The digestion system described in claim 1, wherein the digested sludge in the second piping is heated by the second heater by controlling the heat source system so that the second fluid is heated by at least one of the specific heat source devices.

4. The digestion system according to claim 1 , further comprising a third pipe connected between the first heater and the tank in the first pipe and supplying primary sludge to the first pipe.

5. Further, a cooling system capable of cooling the second fluid is provided, The digestion system described in claim 1, wherein the control device controls the cooling system so that the second fluid is cooled when the temperature in the tank exceeds an upper threshold, thereby cooling the digested sludge in the second piping by the second heater.

6. A heating control method for a digestion system comprising: a tank for digesting sludge; a first pipe for supplying excess sludge to the tank; a second pipe for circulating the digested sludge in the tank between the tank and the outside; a first heater for heating the excess sludge in the first pipe with a first fluid; a second heater for heating the digested sludge in the second pipe with a second fluid; and a heat source system including a plurality of heat source devices capable of heating each of the first fluid and the second fluid, A heating control method that controls at least one of the heating of the excess sludge in the first pipe by the first heater and the heating of the digested sludge in the second pipe by the second heater by controlling the heat source system based on the temperature related to the digestion.

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