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 tank that performs digestion of sludge; a first pipe that supplies surplus sludge to the tank; a second pipe that circulates digested sludge between inside and outside of the tank; a first temperature adjuster that heats or cools, with a fluid, at least one of the surplus sludge in the first pipe and the digested sludge in the second pipe; and a control device that, based on a temperature related to digestion, supplies to the first temperature adjuster at least one of a first fluid and a second fluid having a temperature lower than the first fluid, as the fluid.SELECTED DRAWING: Figure 3

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 temperature regulator for heating or cooling at least one of the excess sludge in the first pipe and the digested sludge in the second pipe using a fluid, and a control device for supplying at least one of the first fluid and a second fluid having a lower temperature than the first fluid to the first 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 configuration of the temperature adjustment system 100 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. [Figure 8] FIG. 8 is a diagram illustrating the configuration of a temperature adjustment system 100 in a modified example. [Figure 9] FIG. 9 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] 2 and 3 are diagrams 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 a first temperature adjuster 110), a pump P1, and a pump P2.

[0022] As shown in FIG. 3, the temperature adjustment system 100 in this embodiment further includes, for example, a heat source device 111, a cooler 112, and a pump P3.

[0023] Pump P1 is provided, for example, in line L1, and supplies excess sludge from the thickening device 50 to the temperature regulator 110, and further supplies the excess sludge whose temperature has been adjusted by the temperature regulator 110 to the digestion tank 60. Line L1 is, for example, a pipe that sequentially connects the thickening device 50, the temperature regulator 110, and the digestion tank 60. Hereinafter, line L1 will also be referred to as the first pipe.

[0024] Pump P2 is provided, for example, on line L3, and supplies digested sludge supplied from the digester 60 via lines L3 and L1 to the temperature regulator 110, and then supplies the digested sludge, the temperature of which has been adjusted by the temperature regulator 110, to the digester 60. Line L3 is, for example, a pipe connecting the digester 60 to a position on line L1 between pump P1 and the temperature regulator 110. Hereinafter, line L3 and the portion of line L1 between the junction with line L3 and the digester 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.

[0025] The temperature regulator 110 heats, for example, excess sludge supplied from the thickener 50 via line L1 (excess sludge before being supplied to the digester 60). The temperature regulator 110 also heats or cools, for example, digested sludge supplied from the digester 60 via lines L3 and L1. 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 circulating through line L2. As shown in FIG. 3, line L2 is, for example, a circulation pipe that connects the temperature regulator 110, the heat source device 111, and the cooler 112. Hereinafter, line L2 will also be referred to as the third pipe.

[0026] As shown in FIG. 3, the pump P3 is provided, for example, in the line L2, and circulates a fluid (for example, a fluid such as hot water) between the temperature regulator 110, the heat source device 111, and the cooler 112.

[0027] The heat source device 111 heats the fluid supplied from the temperature regulator 110 via, for example, a line L2.

[0028] Specifically, the heat source device 111 is, for example, a heat exchanger 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. Alternatively, the heat source device 111 is, for example, a heat exchanger that heats a fluid with waste heat generated in conjunction with power generation using the digester gas discharged from the digester tank 60. Alternatively, the heat source device 111 is, for example, a water heater that heats a fluid by using the digester gas discharged from the digester tank 60.

[0029] The cooler 112 cools the fluid supplied from the temperature regulator 110 or the heat source device 111 via the line L2, for example.

[0030] Specifically, the cooler 112 is, for example, a heat exchanger that cools a fluid with cooling water (e.g., treatment water in the treatment system 1000) supplied from a refrigerant source (not shown) via a line L11. The line L11 is, for example, a circulation pipe that connects the cooler 112 and the refrigerant source.

[0031] Furthermore, the line L2 is provided with, for example, a line L2a that bypasses the heat source device 111. The line L2a is, for example, a pipe that connects a position on the line L2 between the temperature regulator 110 and the heat source device 111 and a position between the heat source device 111 and the cooler 112. Hereinafter, the line L2a is also referred to as a first bypass pipe.

[0032] Furthermore, the line L2 is provided with, for example, a line L2b that bypasses the cooler 112. The line L2b is, for example, a pipe that connects a position on the line L2 between the heat source device 111 and the cooler 112 to a position between the cooler 112 and the temperature regulator 110. Hereinafter, the line L2b is also referred to as a second bypass pipe.

[0033] That is, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 110 via the line L2 to the cooler 112 without supplying it to the heat source device 111, for example. In other words, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 111 via the line L2 to the cooler 112 without heating it by the heat source device 111. Furthermore, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 110 or the heat source device 111 via the line L2 to the temperature regulator 110 without supplying it to the cooler 112, for example. In other words, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 110 or the heat source device 111 via the line L2 to the temperature regulator 110 without cooling it by the cooler 112, for example.

[0034] Therefore, the treatment system 1000 in this embodiment can adjust the temperature of the fluid supplied to the temperature regulator 110 by adjusting, for example, at least one of the amount of fluid supplied to the heat source device 111 (the amount of fluid bypassing the heat source device 111) and the amount of fluid supplied to the cooler 112 (the amount of fluid bypassing the cooler 112), thereby making it possible to accurately adjust the heating temperature of the excess sludge and the heating temperature (cooling temperature) of the digested sludge in the temperature regulator 110. Therefore, the treatment system 1000 in this embodiment can accurately adjust the temperatures of the excess sludge and the digested sludge supplied to the digestion tank 60, for example.

[0035] 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, and can 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, suppress a decrease in the digestion rate in the digestion tank 60.

[0036] Furthermore, in the processing system 1000 of this embodiment, for example, by appropriately changing the temperature of the fluid supplied to the temperature regulator 110, it is not necessary to switch the type of fluid supplied to the temperature regulator 110. Therefore, in the processing system 1000 of this embodiment, it is not necessary to circulate, in the line L2, a fluid (for example, treated water in the processing system 1000) that may have an adverse effect on the heat source device 111 or the like.

[0037] That is, in the processing system 1000 of this embodiment, for example, the fluid (heat medium) supplied to the heat source device 111 does not mix with other fluids (e.g., treated water for cooling), so it is possible to prevent the fluid supplied to the heat source device 111 from being contaminated by other fluids.

[0038] The processing system 1000 in this embodiment may, for example, supply all of the fluid supplied from the temperature regulator 110 via the line L2 to the heat source device 111, and may not supply all of the fluid supplied from the heat source device 111 via the line L2 to the cooler 112. That is, the processing system 1000 in this embodiment may, for example, supply the fluid supplied from the temperature regulator 110 via the line L2 only to the heat source device 111 out of the heat source device 111 and the cooler 112.

[0039] Furthermore, the processing system 1000 in this embodiment may, for example, not supply all of the fluid supplied from the temperature regulator 110 via the line L2 to the heat source device 111, and may supply all of the fluid supplied from the temperature regulator 110 via the line L2 to the cooler 112. That is, the processing system 1000 in this embodiment may, for example, supply the fluid supplied from the temperature regulator 110 via the line L2 only to the cooler 112 out of the heat source device 111 and the cooler 112.

[0040] [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.

[0041] 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).

[0042] 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.

[0043] 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).

[0044] The CPU 201 performs temperature adjustment control by executing a program 210 loaded into the memory 202 from the storage medium 204, for example.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] [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.

[0049] 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.

[0050] 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).

[0051] 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).

[0052] 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 line L3 (the temperature of the excess sludge before it is supplied to the digestion tank 60).

[0053] 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).

[0054] 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.

[0055] [Specific example (1) of temperature control process in the first embodiment] Next, a first specific example of the temperature control process in the first embodiment (hereinafter also simply referred to as the first specific example) will be described. The first specific example is, for example, a specific example in which the temperature of excess sludge is adjusted (excess sludge is heated) in the temperature regulator 110. The first specific example will be described below with reference to FIGS. 2 and 3.

[0056] Specifically, the control device 200, for example, controls the opening of a valve V1 located downstream of the pump P1 on the line L1 and upstream of the junction with the line L3, and controls the closing of a valve V2 located downstream of the pump P2 on the line L3 and upstream of the junction with the line L1, and further controls the pump P1 to supply excess sludge supplied via the line L1 to the temperature regulator 110, and to supply excess sludge whose temperature has been adjusted in the temperature regulator 110 to the digestion tank 60.

[0057] 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 opening of valve V11, which is provided downstream of the branch point of line L2a on line L2 and upstream of the heat source device 111, control to increase the opening of valve V12, which is provided downstream of the heat source device 111 and upstream of the junction point of line L2 with line L2a on line L2, and control to decrease the opening of valve V13, which is provided on line L2a.

[0058] Furthermore, in this case, the control device 200 performs control to reduce the opening of valve V14, which is provided downstream of the branch point of line L2b on line L2 and upstream of the cooler 112, control to reduce the opening of valve V15, which is provided downstream of the cooler 112 and upstream of the junction point of line L2 with line L2b on line L2, and control to increase the opening of valve V16, which is provided on line L2b.

[0059] That is, the control device 200, for example, controls the amount of fluid supplied from the temperature regulator 110 to the heat source device 111 to increase, and controls the amount of fluid supplied from the temperature regulator 110 (heat source device 111) to the cooler 112 to decrease.

[0060] This allows the control device 200 to, for example, increase the temperature of the fluid circulating through line L2, and increase the heating temperature of the excess sludge in the temperature regulator 110. Therefore, the control device 200 can, for example, increase the temperature of the digested sludge in the digestion tank 60.

[0061] In this case, the control device 200 may, for example, perform control to fully open the valve V11, control to fully open the valve V12, and control to fully close the valve V13. In this case, the control device 200 may, for example, perform control to fully close the valve V14, control to fully close the valve V15, and control to fully open the valve V16.

[0062] Also, 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 determines that a predetermined condition is satisfied, and performs control to reduce the opening of valve V11, control to reduce the opening of valve V12, and control to increase the opening of valve V13.

[0063] Furthermore, in this case, the control device 200 performs control to increase the opening degree of the valve V14, control to increase the opening degree of the valve V15, and control to decrease the opening degree of the valve V16, for example.

[0064] That is, the control device 200, for example, controls the amount of fluid supplied from the temperature regulator 110 to the heat source device 111 to decrease, and controls the amount of fluid supplied from the temperature regulator 110 (heat source device 111) to the cooler 112 to increase.

[0065] This allows the control device 200 to, for example, lower the temperature of the fluid circulating through line L2, and to lower the heating temperature of the excess sludge in the temperature regulator 110. Therefore, the control device 200 can, for example, lower the temperature of the digested sludge in the digestion tank 60.

[0066] In this case, the control device 200 may perform, for example, control to fully close the valve V11, control to fully close the valve V12, and control to fully open the valve V13. In this case, the control device 200 may perform, for example, control to fully open the valve V14, control to fully open the valve V15, and control to fully close the valve V16.

[0067] [Specific example (2) of temperature control process in the first embodiment] Next, a second specific example of the temperature control process in the first embodiment (hereinafter simply referred to as the second specific example) will be described. The second specific example is, for example, a specific example in which the temperature of digested sludge is adjusted (heated or cooled) in the temperature regulator 110. The second specific example will be described below with reference to FIGS. 2 and 3.

[0068] Specifically, the control device 200, for example, controls the closing of valve V1 and the opening of valve V2, and further controls pump P2 to supply digested sludge supplied from the digestion tank 60 via line L3 and line L1 to the temperature regulator 110, and also supplies digested sludge whose temperature has been adjusted in the temperature regulator 110 to the digestion tank 60.

[0069] More specifically, for example, when excess sludge is not being supplied from line L1 (concentration device 50), the control device 200 controls to close valve V1 and to open valve V2, and further controls pump P2 to supply digested sludge supplied from the digestion tank 60 via lines L3 and L1 to the temperature regulator 110, and also supplies digested sludge whose temperature has been adjusted in the temperature regulator 110 to the digestion tank 60.

[0070] 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 similarly to the first specific example, performs control to increase the opening of valve V11, control to increase the opening of valve V12, and control to decrease the opening of valve V13. The second lower threshold may be, for example, a value different from or the same as the first lower threshold.

[0071] Furthermore, in this case, the control device 200 performs control to decrease the opening degree of the valve V14, control to decrease the opening degree of the valve V15, and control to increase the opening degree of the valve V16, for example, as in the first specific example.

[0072] This allows the control device 200 to, for example, increase the temperature of the fluid circulating through line L2, and increase the heating temperature of the digested sludge in the temperature regulator 110. Therefore, the control device 200 can, for example, increase the temperature of the digested sludge in the digestion tank 60.

[0073] In this case, the control device 200 may, for example, perform control to fully open the valve V11, control to fully open the valve V12, and control to fully close the valve V13. In this case, the control device 200 may, for example, perform control to fully close the valve V14, control to fully close the valve V15, and control to fully open the valve V16.

[0074] Furthermore, for example, if it is determined that the temperature acquired in step S1 is above a predetermined upper limit threshold (hereinafter also referred to as a second upper limit threshold), the control device 200 determines that a predetermined condition is satisfied, and performs control to decrease the opening of valve V11, control to decrease the opening of valve V12, and control to increase the opening of valve V13, as in the first specific example. The second upper limit threshold may be, for example, a value different from or the same as the first upper limit threshold.

[0075] Furthermore, in this case, the control device 200 performs control to increase the opening degree of the valve V14, control to increase the opening degree of the valve V15, and control to decrease the opening degree of the valve V16, for example, as in the first specific example.

[0076] This allows the control device 200 to lower the temperature of the fluid circulating through line L2, as in the first specific example, and to lower the heating temperature of the digested sludge in the temperature regulator 110. Therefore, the control device 200 can lower the temperature of the digested sludge in the digestion tank 60, for example.

[0077] In this case, the control device 200 may perform, for example, control to fully close the valve V11, control to fully close the valve V12, and control to fully open the valve V13. In this case, the control device 200 may perform, for example, control to fully open the valve V14, control to fully open the valve V15, and control to fully close the valve V16.

[0078] 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 line L3 for circulating the digested sludge in the digestion tank 60 together with line L1 between the digestion tank 60 and the outside, a temperature regulator 110 (hereinafter also referred to as a first temperature regulator) for heating or cooling at least one of the excess sludge in line L1 and the digested sludge in line L3 with a fluid, and a control device 200 for supplying at least one of a fluid (hereinafter also referred to as a first fluid) and another fluid (hereinafter also referred to as a second fluid) having a temperature lower than that of the first fluid to the temperature regulator 110 based on a temperature related to digestion. The temperature related to digestion is, for example, a temperature related to digestion, such as the temperature inside the digestion tank 60, the temperature of the digested sludge itself, or the temperature of the excess sludge itself.

[0079] Specifically, the processing system 1000 in this embodiment includes, for example, a line L2 that supplies a fluid to a temperature regulator 110, a heat source device 111 (hereinafter also referred to as a first heater) that heats the fluid, a cooler 112 (hereinafter also referred to as a first cooler 112) that cools the fluid, a line L2a (hereinafter also referred to as a first bypass pipe) that communicates with the line L2 and bypasses the heat source device 111, and a line L2b (hereinafter also referred to as a second bypass pipe) that communicates with the line L2 and bypasses the cooler 112 (hereinafter also referred to as the first cooler). The first fluid is, for example, a fluid supplied to the line L2b. The second fluid is, for example, a fluid supplied to the line L2a.

[0080] Furthermore, in the treatment system 1000 of this embodiment, the control device 200 controls the first fluid to be supplied to the temperature regulator 110, for example, when excess sludge is supplied to the digestion tank 60 via line L1 and the temperature inside the digestion tank 60 is below the first lower threshold.

[0081] Furthermore, in the treatment system 1000 of this embodiment, the control device 200 controls the first fluid to be supplied to the temperature regulator 110, for example, when digested sludge circulates between the inside and outside of the digestion tank 60 via line L3 and the temperature inside the digestion tank 60 is below the second lower threshold.

[0082] Furthermore, in the treatment system 1000 of this embodiment, the control device 200 controls the second fluid to be supplied to the temperature regulator 110, for example, when digested sludge circulates between the inside and outside of the digestion tank 60 via line L3 and the temperature inside the digestion tank 60 exceeds the second upper limit threshold.

[0083] That is, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 110 via the line L2 to the cooler 112 without supplying it to the heat source device 111. Furthermore, the processing system 1000 in this embodiment can supply at least a portion of the fluid supplied from the temperature regulator 110 or the heat source device 111 via the line L2 to the temperature regulator 110 without supplying it to the cooler 112.

[0084] Therefore, the treatment system 1000 in this embodiment can adjust the temperature of the fluid supplied to the temperature regulator 110 by adjusting, for example, at least one of the amount of fluid supplied to the heat source device 111 (the amount of fluid bypassing the heat source device 111) and the amount of fluid supplied to the cooler 112 (the amount of fluid bypassing the cooler 112), thereby making it possible to accurately adjust the heating temperature of the excess sludge and the heating temperature (cooling temperature) of the digested sludge in the temperature regulator 110. Therefore, the treatment system 1000 in this embodiment can accurately adjust the temperatures of the excess sludge and the digested sludge supplied to the digestion tank 60, for example.

[0085] 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, and can 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, suppress a decrease in the digestion rate in the digestion tank 60.

[0086] [Temperature Adjustment System 100 in Modification] Next, a temperature adjustment system 100 in a modified example will be described. Figs. 7 to 9 are diagrams illustrating the configuration of the temperature adjustment system 100 in the modified example. Below, differences from the temperature adjustment system 100 in the first embodiment will be described. In the examples shown in Figs. 7 to 9, lines corresponding to solid lines indicate that the valves provided in each line are open. In addition, in the examples shown in Figs. 7 to 9, lines corresponding to dashed lines indicate that the valves provided in each line are closed.

[0087] As shown in Figures 7 to 9, the temperature adjustment system 100 in this modified example has, for example, a temperature adjuster 120 (hereinafter also referred to as a second temperature adjuster 120) in addition to each component of the temperature adjustment system 100 in the first embodiment.

[0088] The temperature regulator 120 heats, for example, excess sludge supplied from the concentrator 50 via line L1 (excess sludge before being supplied to the digester 60). The temperature regulator 110 heats or cools, for example, digested sludge supplied from the digester 60 via lines L3 and L1. Specifically, the temperature regulator 120 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 circulating through line L6. The line L6 is, for example, a circulation pipe that connects the temperature regulator 120 with a heat source device (not shown) and a cooler (not shown). The configuration of line L6 (including the temperature regulator 120, the heat source device, and the cooler) may be the same as the configuration of line L2 described in FIG. 3 (including the temperature regulator 110, the heat source device 111, and the cooler 112).

[0089] Line L1 is also provided with, for example, lines L4 and L5 that bypass the heat source device 111. Line L4 is, for example, a pipe that communicates with line L5 and extends from a position on line L1 between pump P1 and temperature regulator 110 to a connection point with line L5. Line L5 is, for example, a pipe that communicates with line L4 and extends from the connection point with line L4 to a position on line L1 between the temperature regulator 110 and digester 60. Hereinafter, line L4 and line L5 are also collectively referred to as third bypass pipes.

[0090] In this modification, pump P2 is provided, for example, on line L3a. Line L3a is, for example, a pipe connecting digestion tank 60 with the connection point of line L4 and line L5. That is, in this modification, line L3 is made up of, for example, line L3a, line L4, and line L5.

[0091] For example, when heating the temperature of excess sludge supplied through line L1, the control device 200 performs control to open valve V1, control to close valve V2, control to open valve V3 located downstream of the branch point of line L1 to line L4 and upstream of temperature regulator 110, control to open valve V4 located on line L4, and control to open valve V5 located downstream of the connection point of line L5 with line L4 and upstream of temperature regulator 120, as shown in Figure 7.

[0092] That is, in this case, the control device 200 uses, for example, the temperature regulator 110 and the temperature regulator 120 as equipment for adjusting the temperature of the excess sludge.

[0093] Specifically, in this case, the control device 200 heats the excess sludge before it is supplied to the digestion tank 60 by heating each of the fluid supplied to the temperature regulator 110 via line L2 and the fluid supplied to the temperature regulator 120 via line L6, for example, as described in Figure 3.

[0094] In this case, the control device 200 may, for example, heat the excess sludge by using either the temperature regulator 110 or the temperature regulator 120. Specifically, the control device 200 may, for example, further control the closing of valve V4 and the closing of valve V5, thereby heating the excess sludge only in the temperature regulator 110. Furthermore, the control device 200 may, for example, further control the closing of valve V3, thereby heating the excess sludge only in the temperature regulator 120.

[0095] Furthermore, for example, when heating (cooling) the temperature of digested sludge supplied from the digestion tank 60 via line L3, the control device 200 controls to close valve V1, open valve V2, open valve V3, open valve V4, and open valve V5, as shown in Figure 8.

[0096] That is, in this case, the control device 200 uses, for example, the temperature regulator 110 and the temperature regulator 120 as equipment for adjusting the temperature of the digested sludge.

[0097] Specifically, in this case, the control device 200 adjusts the temperature of the digested sludge before it is supplied again to the digestion tank 60 by adjusting the temperature of the fluid supplied to the temperature regulator 110 via line L2 and the temperature of the fluid supplied to the temperature regulator 120 via line L6, for example, as described in Figure 3.

[0098] In this case, the control device 200 may, for example, heat (cool) the digested sludge by using either the temperature regulator 110 or the temperature regulator 120. Specifically, the control device 200 may, for example, further control the closing of the valve V4 and the valve V5, thereby heating the digested sludge only in the temperature regulator 110. Furthermore, the control device 200 may, for example, further control the closing of the valve V3 and the valve V4, thereby heating the digested sludge only in the temperature regulator 120.

[0099] Furthermore, for example, when simultaneously heating the temperature of excess sludge supplied via line L1 and heating (cooling) the temperature of digested sludge supplied from the digestion tank 60 via line L3, the control device 200 controls to open valve V1, open valve V2, open valve V3, close valve V4, and open valve V5, as shown in Figure 9.

[0100] That is, in this case, the control device 200 uses, for example, the temperature regulator 110 as equipment for adjusting the temperature of excess sludge, and the temperature regulator 120 as equipment for adjusting the temperature of digested sludge.

[0101] Specifically, in this case, the control device 200 adjusts the temperature of the excess sludge before it is supplied to the digestion tank 60 by adjusting the temperature of the fluid supplied to the temperature regulator 110 via line L2, as in the case described in Figure 3, and adjusts the temperature of the digested sludge before it is supplied again to the digestion tank 60 by adjusting the temperature of the fluid supplied to the temperature regulator 120 via line L6.

[0102] Thus, the treatment system 1000 of this modified example includes, for example, lines L4 and L5 that communicate with line L1 and bypass the temperature regulator 110, and a temperature regulator 120 that uses a fluid to heat or cool at least one of the excess sludge and digested sludge in lines L4 and L5. In the treatment system 1000 of this modified example, the control device 200 controls the supply of excess sludge to at least one of lines L4 and L5 based on, for example, a temperature related to digestion. In the treatment system 1000 of this modified example, the control device 200 controls the supply of digested sludge to at least one of lines L4 and L5 based on, for example, a temperature related to digestion.

[0103] That is, the treatment system 1000 in this modification can appropriately switch the target of temperature adjustment between excess sludge and digested sludge by each of the temperature regulators 110 and 120. Furthermore, the treatment system 1000 in this modification can appropriately change the temperature of the fluid supplied to each of the temperature regulators 110 and 120, for example.

[0104] 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.

[0105] Furthermore, in the treatment system 1000 of this modified example, for example, the temperature regulator 110 and the temperature regulator 120 are arranged in parallel, thereby ensuring redundancy. Specifically, in the treatment system 1000 of this modified example, even if one of the temperature regulator 110 and the temperature regulator 120 fails, for example, it is possible to continue regulating the temperature of at least one of the excess sludge and the digested sludge by using the other of the temperature regulator 110 and the temperature regulator 120.

[0106] 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, and V5, 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 and P2, etc.

[0107] Furthermore, in the processing system 1000 according to the first embodiment and the modified examples, for example, the amount of fluid supplied to the heat source device 111 and the cooler 112 is adjusted by controlling the opening and closing of the valves V11, V12, V13, V14, V15, and V16, but this is not limiting. Specifically, in the processing system 1000 according to the first embodiment and the modified examples, for example, the amount of fluid supplied to the heat source device 111 and the cooler 112 may be adjusted by controlling the rotation speed of the pump P3, etc. [Explanation of symbols]

[0108] 10: Primary sedimentation tank 20: Reaction tank 30: Final settling tank 40: Thickener 50: Concentrator 60: Digestion tank 100: Temperature control system 110: Temperature controller 111: Heat source device 112: Cooler 120: Temperature regulator 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 L3a: Line L4: Line L5: Line L6: Line L11: Line P1: Pump P2: Pump P3: Pump T: Thermometer V1: Valve V2: Valve V3: Valve V4: Valve V5: Valve V11: Valve V12: Valve V13: Valve V14: Valve V15: Valve V16: 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 temperature regulator that heats or cools at least one of the excess sludge in the first pipe and the digested sludge in the second pipe using a fluid; A fire extinguishing system comprising: a control device that supplies at least one of a first fluid and a second fluid having a lower temperature than the first fluid to a first temperature regulator based on the temperature related to the fire extinguishing.

2. a third pipe that supplies the fluid to the first temperature regulator; a first heater for heating the fluid; a first cooler for cooling the fluid; a first bypass pipe communicating with the third pipe and bypassing the first heater; a second bypass pipe communicating with the third pipe and bypassing the first cooler, the first fluid is the fluid supplied to the second bypass pipe, 2. The fire extinguishing system of claim 1, wherein the second fluid is the fluid supplied to the first bypass pipe.

3. The digestion system described in claim 1, wherein the control device controls the first fluid to be supplied to the first temperature regulator when the excess sludge is supplied to the tank through the first piping and the temperature in the tank is below a lower threshold.

4. The digestion system described in claim 1, wherein the control device controls the first fluid to be supplied to the first temperature regulator when the digested sludge circulates between the inside and outside of the tank via the second piping and the temperature inside the tank is below a lower threshold.

5. The digestion system described in claim 1, wherein the control device controls the second fluid to be supplied to the first temperature regulator when the digested sludge circulates between the inside and outside of the tank via the second piping and the temperature inside the tank exceeds an upper threshold.

6. The first piping has a part of the piping in common with the second piping, the first temperature regulator is provided in the partial pipe, a third bypass pipe communicating with the second pipe and bypassing the first temperature regulator; a second temperature regulator that heats or cools at least one of the excess sludge in the third bypass pipe and the digested sludge in the third bypass pipe by a fluid, The digestion system described in claim 1, wherein the control device controls at least one of the supply of excess sludge to the third bypass pipe and the supply of digested sludge to the third bypass pipe based on the temperature related to the digestion.

7. A heating control method for a digestion system including 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, and a first temperature regulator for heating or cooling at least one of the excess sludge in the first pipe and the digested sludge in the second pipe by a fluid, comprising: A heating control method comprising: a control device that supplies at least one of a first fluid and a second fluid having a lower temperature than the first fluid to the first temperature regulator based on the temperature related to the extinguishing.

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