Heat Recovery System

Abstract

To provide a heat recovery system that efficiently recovers high-temperature drainage from multiple systems discharged from manufacturing facilities and effectively reuses the sensible heat as a heat source for boiler water supply, snow melting, and heating. [Solution] The heat recovery system comprises a drain pit (16) that collects high-temperature drainage discharged from manufacturing equipment, multiple falling film heat recovery devices (18) that perform heat exchange by causing high-temperature drainage supplied from the drain pit or each manufacturing facility to flow down onto a heat transfer surface, and a piping system that directs water heated in each heat recovery device to a boiler feedwater tank (19) or a snow melting / heating system. The multiple falling film heat recovery devices are individually connected to different high-temperature drain sources, such as an unrecovered drain system, a recovered drain system, a boiler blowout drain system, and a cleaning drain system, and are configured to perform heat exchange independently for each system. This makes it possible to effectively recover the thermal energy of various high-temperature drainage, reduce fuel consumption, and lower the drainage temperature.

Description

[Technical Field]

[0001] The present invention relates to a heat recovery system, and more particularly to a heat recovery system using a falling film heat recovery device. [Background technology]

[0002] Conventionally, as shown in Patent Document 1, for example, in factories and the like, steam supplied from a steam boiler is used to operate manufacturing machines, dryers, washers, etc., and high-temperature drain water and boiler blowdown wastewater are generated in the process. Conventionally, this has been discharged without sufficient heat recovery, resulting in energy loss and environmental load. In particular, in food manufacturing factories and the like, despite the large amount of high-temperature drain water generated by the use of kneaders, dryers, etc., it cannot be said that the heat is being used effectively enough. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-308525 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention was made in consideration of the above points, and its purpose is to provide a heat recovery system that can efficiently recover the heat from high-temperature drainage and blowdown water generated by factory facilities and use it to heat low-temperature media such as boiler feed water and water for snow melting and heating, thereby reducing fuel consumption, improving energy utilization efficiency, and reducing environmental impact. [Means for solving the problem]

[0005] In order to achieve the above object, the heat recovery system of the present invention is a heat recovery system that recovers high-temperature drainage discharged from manufacturing equipment and performs heat exchange, and is characterized by comprising: a drain pit that collects the high-temperature drainage; a plurality of falling film heat recovery devices that perform heat exchange by causing the high-temperature drainage supplied from the drain pit or each manufacturing equipment to flow down onto a heat transfer surface; and a piping system that directs the water heated by each of the falling film heat recovery devices to a boiler water tank or a snow melting / heating system, and the plurality of falling film heat recovery devices are each individually connected to a different high-temperature drain system, and each system performs heat exchange individually.

[0006] In addition, in this heat recovery system, the high-temperature drain may include unrecovered drain, recovered drain, boiler body blowout drain, and washing drain, and these different high-temperature drains may be introduced individually into the plurality of falling film heat recovery devices to perform heat exchange.

[0007] Furthermore, this heat recovery system may have a configuration in which the high-temperature drain discharged from the drain pit is introduced into at least one of the plurality of falling film heat recovery devices, and the other high-temperature drain systems are introduced directly into the falling film heat recovery devices from the manufacturing facility side.

[0008] In addition, this heat recovery system may be configured such that either or both of a snow melting facility and a heating facility are connected to a portion of the piping system, and the recovered heat obtained by the plurality of falling film type heat recovery devices is used as a heat source for snow melting or heating.

[0009] In one embodiment, the heat recovery system of the present invention includes a drain pit for collecting high-temperature drainage and can body blown water discharged from a steam boiler and manufacturing equipment that uses the steam, such as a kneader, molding machine, dryer, and washer. The system also includes a falling film heat recovery device that allows the drainage to flow down a heat transfer surface to form a thin liquid film, which then exchanges heat with a low-temperature medium flowing countercurrently or crosswise. The outlet of the heat recovery device is connected to a low-temperature piping system connected to a boiler feedwater tank or a snow melting / heating system. The flow rate and temperature of the high-temperature drainage supplied to the heat recovery device are controlled by instrumentation such as pumps, valves, and level switches. This allows for the integrated recovery of high-temperature water from various systems, such as unrecovered drainage, recovered drainage, can body blown water, and wastewater from a food container washer, and allows for efficient heating of the low-temperature water. [Effects of the Invention]

[0010] According to the heat recovery system of the present invention, high-temperature drains generated in a manufacturing facility from multiple systems can be treated individually by falling film heat recovery devices installed independently for each system.

[0011] This allows optimal heat exchange to be performed under each condition, even if the temperature, flow rate, and properties of the drain differ from system to system, achieving high overall heat recovery efficiency.

[0012] Furthermore, since the individual units can process not only the drain collected in the drain pit, but also other high-temperature water such as boiler blow and cleaning wastewater, it is possible to utilize multiple waste heat sources in an integrated manner that were previously not used.

[0013] Furthermore, because each unit is installed independently, it can be easily retrofitted to an existing piping system, making it easy to achieve energy savings in existing factory facilities.

[0014] These configurations increase the boiler feedwater temperature, improving combustion efficiency and reducing fuel consumption, while lowering the drainage temperature to reduce the thermal load on drainage equipment and building structural materials. Furthermore, waste heat from multiple high-temperature drains can be efficiently collected and reused as a heat source for building heating and snow melting equipment, in addition to preheating boiler feedwater. This reduces boiler load in winter, suppressing fuel consumption and improving energy utilization efficiency. Furthermore, by supplying hot water from the heat recovery unit to the snow melting and heating systems even during boiler startup or low-load operation, a stable heat supply can be maintained, promoting the effective use of thermal energy.

[0015] This system can efficiently recover sensible heat from high-temperature drainage, which has previously been unused or underutilized, significantly reducing fuel consumption. Lowering the wastewater temperature also reduces the wastewater treatment load. Furthermore, the recovered heat can be used for secondary purposes such as snow melting and heating, ensuring stable and effective heat utilization even during seasonal fluctuations. Furthermore, the system can be retrofitted into existing factories, contributing to energy conservation in food factories and other industrial fields in general. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing the overall configuration of a heat recovery system according to the present invention. [Figure 2] 1 is a schematic diagram showing an example of the use of recovered heat in a heat recovery system according to the present invention. [Figure 3] 1 is a diagram showing an example of the configuration of instrumentation and piping in a heat recovery system of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Figure 1 is a system diagram showing the overall configuration of the heat recovery system of the present invention. The heat recovery system 1 of the present invention recovers high-temperature drainage generated by condensation of steam used in manufacturing facilities and reuses the sensible heat as boiler feedwater or a heat source for snow melting and heating.

[0018] The heat recovery system 1 is composed of a steam boiler 11, multiple manufacturing facilities that use steam, such as a kneading machine 12, a molding machine 13, a dryer 14, a box washer 15, a drain pit 16 that collects high-temperature drain, multiple falling film heat recovery devices 18 (18-1 to 18-4), piping lines connecting these, and a boiler water tank 19.

[0019] In manufacturing equipment such as the kneading machine 12, molding machine 13, dryer (product dryer) 14, and box washer 15, the steam used in the steam heating process condenses and is discharged as high-temperature drain. Because the temperature, flow rate, and contaminant components of this drain vary depending on the equipment, it is introduced separately from each system into the drain pit 16. The drain pit 16 is a tank for temporarily storing high-temperature drain, and is equipped with a liquid level sensor 32 (see Figure 3) and pumps 17 (first pump 17-1, second pump 17-2) inside, which automatically controls discharge according to the amount of drainage stored.

[0020] The first to fourth heat recovery units 18-1 to 18-4 are each independently provided, and each unit is configured to recover heat (heat exchange) at a different location. As shown in Fig. 1, the first heat recovery unit 18-1 is configured to perform heat exchange between high-temperature water discharged from the drain pit 16 and city water introduced into the drain pit 16 via a water softener 20. The second heat recovery unit 18-2 is configured to perform heat exchange between boiler body blowdown wastewater from the steam boiler 11 and city water introduced into a boiler feed water tank 19 via the water softener 20. The third heat recovery unit 18-3 is configured to perform heat exchange between tap water introduced into the box container washer 15 and wastewater discharged from the box container washer 15. The fourth heat recovery unit 18-4 is configured to perform heat exchange between wastewater discharged from the kneader 12 and introduced into the drain pit 16 and city water introduced into the boiler feed water tank 19 via the water softener 20.

[0021] The first to fourth heat recovery units 18-1 to 18-4 have a falling film structure in which high-temperature drainage introduced from above flows down onto a heat transfer surface to form a liquid film, which then exchanges heat with a low-temperature medium (such as water) flowing inside. By forming a liquid film, the heat transfer area is large, resulting in stable heat transfer. For example, a heat recovery unit (heat exchange unit) having the configuration disclosed in Japanese Patent No. 6902582 can be used as this type of falling film type heat recovery unit.

[0022] The four first to fourth heat recovery units 18-1 to 18-4 function as independent systems, treating different high-temperature drain sources individually, thereby achieving comprehensive heat recovery throughout the factory. The heated water obtained by heat exchange in the first to fourth heat recovery units 18-1 to 18-4 is returned to the boiler feedwater tank 19 through a piping line, thereby improving the overall energy circulation efficiency.

[0023] Next, Figure 2 is a schematic diagram showing an example of how the recovered heat from the heat recovery system of the present invention can be used. In this embodiment, the recovered heat can be divided and used for two purposes: the first is to preheat boiler feedwater, and the second is to melt snow and serve as a heat source for heating and cooling.

[0024] First, as shown in FIG. 1, in the case of boiler feedwater preheating, hot water heated in the first to fourth heat recovery devices 18-1 to 18-4 is returned to the boiler feedwater tank 19. This preheating improves the combustion efficiency of the steam boiler 11 and reduces fuel consumption. Furthermore, the increase in feedwater temperature reduces the thermal load during steam generation in the steam boiler 11, contributing to extending the life of the equipment.

[0025] Next, as shown in Figure 2, for snow melting and heating / cooling applications, the recovered hot water is circulated as a heat transfer medium to snow melting piping 22 outside the building and heating coils 21 inside the building. Figure 2(a) shows an example of a structure in which recovered hot water is circulated as a heat transfer medium to heating coils 21 inside the building, while Figure 2(b) shows an example of a structure in which recovered hot water is circulated as a heat transfer medium to snow melting piping 22 outside the building. For example, snow melting piping 22 can be installed under plastic parking lot 24 laid in a parking lot 25 covered with gravel 23. As shown in Figure 2(a), for example, if drain water at 95°C is cooled to 35°C and recovered water at 15°C is heated to 67°C, the amount of heat obtained corresponds to a heat recovery efficiency of approximately 65%. This eliminates the need to supply additional heat from the steam boiler 11 during winter heating or snow melting operation, significantly reducing fuel consumption.

[0026] In this way, the heat recovery system 1 of the present invention can flexibly allocate the obtained heat to multiple uses, and can achieve efficient energy use depending on the season and operating load.

[0027] Figure 3 is a diagram showing the detailed configuration of the instrumentation and piping in the heat recovery system of the present invention. This figure shows a schematic representation of a portion of the heat recovery system 1 shown in Figure 1, with the locations of various measuring instruments and the like added. Circled numbers 1 to 11 in Figure 3 are temperature measurement points where thermometers are installed, circled numbers 12 to 15 are flow rate measurement points where flowmeters are installed, and circled numbers 16 to 21 are pressure measurement points where pressure gauges are installed. In this way, thermometers and pressure gauges are installed at the inlet and outlet of the heat recovery device 18, making it easy to monitor the operating status and evaluate performance.

[0028] 3, the drain pit 16 is provided with a level switch (LS) 32 that detects the water level, and the pump 33 is controlled so that it automatically starts when a predetermined high water level signal (LS_H) is received and stops when a low water level signal (LS_L) is received. A check valve 34 and a shutoff valve 35 are provided on the discharge side of the pump 33 to prevent backflow and enable system isolation during maintenance.

[0029] These instrumentation and piping configurations allow the entire heat recovery system 1 to be operated automatically and safely, while also making maintenance and inspection more efficient.

[0030] As described above, the heat recovery system 1 of the present invention recovers multiple high-temperature drains and blown-down wastewater in one go and efficiently recovers heat using a falling film type heat recovery device 18. The recovered heat can then be reused for multiple purposes, such as boiler feedwater, heating and cooling, and snow melting, reducing fuel consumption and lowering the wastewater temperature, thereby mitigating the environmental impact. Furthermore, it has the excellent effect of preventing damage to buildings and equipment caused by steam discharge points and blown-down wastewater, and extending maintenance cycles.

[0031] As described above, the heat recovery system 1 of the present invention introduces high-temperature drainage discharged from manufacturing facilities into a falling film type heat recovery device 18 and uses it as boiler water supply or a heat source for heating, cooling, and snow melting. However, the following configurations are also included.

[0032] As shown in FIG. 1 , high-temperature wastewater from manufacturing equipment such as a kneading machine 12, a molding machine 13, a dryer 14, and a box washer 15 is collected in a drain pit 16. The drain water drawn from the drain pit 16 by a first pump 17-1 is sent to a falling film type heat recovery device 18 (first heat exchanger 18-1), where it flows down as a liquid film on the heat transfer surface and efficiently exchanges heat with a low-temperature medium. Furthermore, the drain water drawn from the drain pit 16 by a second pump 17-2 is introduced into a boiler feedwater tank via a drain collection tank 23 and a membrane treatment device 24. By treating drain water from multiple systems in this way, it is possible to achieve highly efficient heat recovery while simplifying the piping system without requiring individual heat exchange equipment.

[0033] The low-temperature side of the heat recovery unit 18 (fourth heat recovery unit 18-4) shown in FIG. 1 is connected to a boiler feedwater tank 19, and low-temperature water heated in the unit is returned to the boiler feedwater tank 19. High-temperature drain from the drain pit 16 is introduced to the high-temperature side, and heat exchange takes place in a countercurrent or crosscurrent manner. As a result, for example, the low-temperature water (e.g., 15°C) is heated to approximately 67°C in the heat recovery unit and returned to the steam boiler 11, while the high-temperature drain (e.g., 95°C) is cooled to approximately 35°C. With this configuration, the temperature of the water supplied to the steam boiler 11 is increased, reducing the temperature rise load during combustion.

[0034] As shown in Figure 3, thermometers (temperature sensors) are installed at the inlet and outlet of the heat recovery device 18, and the temperatures on the drain and low-temperature sides are constantly monitored. Based on these detected values, the pump rotation speed or the valve opening of the piping system is controlled, optimizing the heat exchange residence time and flow rate according to the actual operating conditions. For example, if the temperature of the high-temperature drain drops, the flow rate is reduced to ensure heat transfer time, and conversely, if a large amount of high-temperature drain flows in at a high temperature, the flow rate is increased to avoid overheating. This makes it possible to maintain stable heat recovery efficiency regardless of the season or load fluctuations.

[0035] 1, the high-temperature drain is cooled to a predetermined temperature while passing through the heat recovery device 18 before being discharged, which reduces the thermal load on surrounding piping and equipment compared to conventional systems where the drain is discharged at a high temperature. This is expected to reduce the thermal impact of steam, improve the maintainability of piping and equipment, and extend maintenance intervals.

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the claims of the utility model registration and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0037] 1. Heat recovery system 11 Steam boiler 12 Kneading machine 13 Molding machine 14 Product dryer No. 15 heavy washing machine 16 Drain pit 17(17-1, 17-2) Pump 18(18-1~18-4) Heat recovery device 19 Boiler feed tank 20 water softener 21 Heating coil 22 Snow melting pipes 23 Gravel 24 Parking vinyl 25 Parking 32 Liquid level sensor 33 Pump 34 Check valve 35 Shut-off valve

Claims

1. A heat recovery system that recovers high-temperature drainage discharged from a manufacturing facility and performs heat exchange, a drain pit for collecting high-temperature drain; a plurality of falling film heat recovery devices that perform heat exchange by causing high-temperature drainage supplied from the drain pit or each manufacturing facility to flow down onto a heat transfer surface; a piping system that guides the water heated by each of the falling film heat recovery devices to a boiler water tank or a snow melting / heating system, The plurality of falling film heat recovery devices are individually connected to different high-temperature drain systems, A heat recovery system characterized by having a configuration in which heat exchange is performed individually in each system.

2. The high-temperature drain includes drainage water from can body blowing and washing in addition to drainage water supplied from each of the manufacturing facilities, 2. The heat recovery system according to claim 1, wherein the different high-temperature drains are introduced individually into the plurality of falling film heat recovery devices to perform heat exchange.

3. 2. The heat recovery system according to claim 1, wherein the high-temperature drain discharged from the drain pit is introduced into at least one of the plurality of falling film type heat recovery devices, and the high-temperature drain for other systems is introduced directly into the falling film type heat recovery device from the manufacturing facility side.

4. The heat recovery system according to any one of claims 1 to 4, characterized in that either or both of a snow melting system and a heating system are connected to a part of the piping system, and the recovered heat obtained by the plurality of falling film type heat recovery devices is used as a heat source for snow melting or heating.

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