Injection molding process cooling waste heat utilization system

Abstract

This application belongs to the field of injection molding technology, specifically relating to a waste heat recovery system for injection molding processes. The system includes: a material supply subsystem, an injection molding subsystem, a cooling subsystem, and a waste heat recovery subsystem. The waste heat recovery subsystem includes: an air compressor and a surface heat exchanger; the surface heat exchanger is connected to both the injection molding subsystem and the cooling subsystem via water pipes; the air compressor is connected to the material supply subsystem via an air pipe; the surface heat exchanger absorbs both low-grade and high-grade waste heat generated by the injection molding subsystem, using the absorbed waste heat to heat the compressed air generated by the air compressor, and then supplies the heated compressed air to the material supply subsystem via the air pipe; the material supply subsystem provides plastic raw materials to the injection molding subsystem, which then performs injection molding on the plastic raw materials; this system can be used in the Industrial Internet, realizing the tiered recovery and reuse of waste heat from the injection molding process, reducing energy and water consumption in the cooling subsystem.

Description

Technical Field

[0001] This application belongs to the field of injection molding technology, specifically relating to a system for utilizing the cooling waste heat of an injection molding process. Background Technology

[0002] Plastic injection molding technology is used to produce plastic products of various shapes and sizes. It is characterized by short molding cycles and high production efficiency, making it the most widely used plastic product molding system. As the core production equipment in the injection molding process, the energy consumption cost of the injection molding machine is a significant factor affecting the production efficiency of the injection molding industry.

[0003] To reduce energy consumption during the injection molding process, existing technologies propose recovering waste heat from injection molding machines. Specifically, this can be achieved by recovering the plasticizing waste heat from the injection molding machine's heating system through thermoelectric power generation, or by using a heat pump to transfer the heat from the mold cooling water to the plasticizing system. The waste heat after plasticizing can also be used to preheat plastic raw material granules.

[0004] However, existing waste heat recovery systems only consider mold heat recovery and raw material preheating in the hopper, failing to address other waste heat sources and heat load requirements, and thus cannot achieve cascade utilization of waste heat. Summary of the Invention

[0005] This application provides a waste heat recovery system for injection molding processes to solve the problems of existing waste heat recovery systems being complex, costly, and unable to achieve cascaded utilization of waste heat.

[0006] In a first aspect, this application provides a system for utilizing the cooling waste heat of an injection molding process, the system comprising:

[0007] The system includes a material supply subsystem, an injection molding subsystem, a cooling subsystem, and a waste heat utilization subsystem, wherein the waste heat utilization subsystem includes an air compressor and a surface heat exchanger.

[0008] The surface heat exchanger is connected to the injection molding subsystem and the cooling subsystem respectively via water injection pipes;

[0009] The air compressor is connected to the feeding subsystem via an air duct;

[0010] The surface heat exchanger is used to absorb the low-grade and high-grade waste heat generated by the injection molding subsystem, and uses the absorbed waste heat to heat the compressed air generated by the air compressor, so that the heated compressed air is supplied to the material supply subsystem through the air pipeline.

[0011] The feeding subsystem is used to supply plastic raw materials to the injection molding subsystem, and the injection molding subsystem is used to perform injection molding on the plastic raw materials.

[0012] Optionally, the waste heat utilization subsystem further includes: a first plate heat exchanger;

[0013] The first plate heat exchanger is connected to the cooling subsystem, the injection molding subsystem, and the surface heat exchanger via water injection pipes. The first plate heat exchanger is used to absorb the low-grade waste heat generated by the injection molding subsystem and the high-grade waste heat generated by the injection molding subsystem, and to transfer the high-grade waste heat and the low-grade waste heat to the surface heat exchanger via the water injection pipes.

[0014] Optionally, the waste heat utilization subsystem includes: a first plate heat exchanger and a second plate heat exchanger;

[0015] The first plate heat exchanger is connected to the injection molding subsystem, the second plate heat exchanger, and the surface heat exchanger via water injection pipes.

[0016] The second plate heat exchanger is connected to the injection molding subsystem and the cooling subsystem respectively via water injection pipes;

[0017] The second plate heat exchanger is used to absorb the low-grade waste heat generated by the injection molding subsystem and transfer the low-grade waste heat to the first plate heat exchanger through the water injection pipe.

[0018] The first plate heat exchanger is used to absorb the high-grade waste heat generated by the injection molding subsystem, and to transfer the high-grade waste heat and the low-grade waste heat transmitted by the second plate heat exchanger to the surface heat exchanger through the water injection pipe.

[0019] Optionally, the injection molding subsystem includes: a first cooling tower, an injection molding machine, and an injection mold;

[0020] The first cooling tower is connected to the first plate heat exchanger and the injection molding machine respectively through water injection pipes. The first cooling tower is used to cool the heat generated by the injection molding machine during operation.

[0021] The injection molding machine is connected to the first plate heat exchanger via a water injection pipe;

[0022] The injection mold is connected to the cooling subsystem and the second plate heat exchanger via water injection pipes.

[0023] Optionally, the feeding subsystem includes: a centralized feeding system and an injection molding machine hopper;

[0024] The centralized material supply system is connected to the air compressor and the injection molding machine hopper via air pipes. The compressed air generated by the air compressor, after being heated, is used to heat the storage tank and air delivery pipe in the centralized material supply system and to pre-dehumidify and dry the injection molding machine hopper via the air pipes.

[0025] Optionally, the cooling subsystem includes: a second cooling tower, a first chiller, and a second chiller;

[0026] The second cooling tower is connected to both the first chiller and the second chiller via the water injection pipe;

[0027] The first chiller and the second plate heat exchanger are connected via the water injection pipe;

[0028] The second chiller is connected to the second plate heat exchanger and the injection mold via the water injection pipe.

[0029] Optionally, the cooling subsystem further includes: at least one water pump;

[0030] The second cooling tower is also connected to the first plate heat exchanger through the water injection pipe. The second cooling tower is used to inject water into the first plate heat exchanger through the water injection pipe when the inlet water temperature of the second cooling tower is higher than the outlet water temperature of the first plate heat exchanger.

[0031] Optionally, the waste heat utilization subsystem further includes: hot water load;

[0032] The surface heat exchanger is connected to the hot water load via a water injection pipe, and the surface heat exchanger is also used to provide heat to the hot water load using the absorbed waste heat.

[0033] Optionally, the waste heat utilization subsystem further includes: a water replenishment tank;

[0034] The surface heat exchanger is connected to the water supply tank via a water supply pipe. The water supply tank is used to replenish the water supply pipe when the flow rate of the circulating water in the water supply pipe decreases.

[0035] Optionally, the number of the injection molding machines may be one or more.

[0036] The waste heat recovery system for injection molding provided in this application absorbs low-grade waste heat generated by the injection mold through a second plate heat exchanger and transfers it to a first plate heat exchanger. The first plate heat exchanger absorbs high-grade waste heat generated by the injection molding machine and transfers both high-grade and low-grade waste heat to a surface heat exchanger via a water injection pipe. Furthermore, when the inlet water temperature of the second cooling tower is higher than the outlet water temperature of the first plate heat exchanger, a water pump draws circulating cooling water from the inlet of the second cooling tower through the water injection pipe and mixes it with the outlet water from the cold side of the first plate heat exchanger. The waste heat is transferred to a surface heat exchanger, which recovers heat and heats the compressed air generated by the air compressor. The heated air is then supplied to the centralized feeding system and the injection molding machine hopper through air pipes, achieving the first stage of waste heat recovery. The remaining waste heat from the surface heat exchanger is supplied to the hot water load, achieving the second stage of waste heat recovery. Water is replenished to the water injection pipe through a water tank. This system realizes the step-by-step recovery and tiered utilization of waste heat in the injection molding process, improves the stability of the feeding subsystem, and reduces the energy and water consumption of the cooling subsystem. Attached Figure Description

[0037] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0038] Figure 1 This is a schematic diagram of the cooling waste heat utilization system for the injection molding process provided in this application;

[0039] Figure 2 This is a schematic diagram of the cooling waste heat utilization system for the injection molding process provided in this application. Figure 1 ;

[0040] Figure 3 This is a schematic diagram of the cooling waste heat utilization system for the injection molding process provided in this application. Figure 2 ;

[0041] Figure 4 This is a schematic diagram of the cooling waste heat utilization system for the injection molding process provided in this application. Figure 3 .

[0042] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0045] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0046] Plastic injection molding technology is used to produce plastic products of various shapes and sizes. It is characterized by short molding cycles and high production efficiency, making it the most widely used plastic product molding system. As the core production equipment in the injection molding process, the energy consumption cost of the injection molding machine is a significant factor affecting the production efficiency of the injection molding industry.

[0047] Energy consumption in injection molding machines mainly occurs in the power system, heating system, and cooling system. Power system energy saving has evolved from fixed-displacement pumps to variable-displacement pumps, frequency converters, servo motors, hybrid electric vehicles, and all-electric systems. Heating system energy saving primarily involves improving insulation and employing efficient heating methods such as electromagnetic induction and nano-infrared heating. Cooling system energy saving focuses on the hydraulic oil lines and mold cooling system, such as optimizing oil line resistance and adopting conformal cooling technology.

[0048] To reduce energy consumption during the injection molding process, existing technologies propose recovering waste heat from injection molding machines. Specifically, this can be achieved by recovering the plasticizing waste heat from the injection molding machine's heating system through thermoelectric power generation, or by using a heat pump to transfer the heat from the mold cooling water to the plasticizing system. The waste heat after plasticizing can also be used to preheat plastic raw material granules.

[0049] However, existing waste heat recovery systems only consider mold heat recovery and raw material preheating in the hopper, failing to address other waste heat sources and heat load requirements, and thus cannot achieve cascade utilization of waste heat.

[0050] To address the aforementioned problems, this application provides a waste heat recovery system for injection molding processes. A second plate heat exchanger absorbs low-grade waste heat generated by the injection mold and transfers it to a first plate heat exchanger. The first plate heat exchanger absorbs high-grade waste heat generated by the injection molding machine. Both high-grade and low-grade waste heat are transferred to a surface heat exchanger via a water injection pipe. The surface heat exchanger recovers heat and heats the compressed air generated by the air compressor before supplying the heated air to the centralized material feeding system and the injection molding machine hopper via an air pipe, achieving the first stage of waste heat recovery. The remaining waste heat from the surface heat exchanger is then supplied to the hot water load, achieving the second stage of waste heat recovery. A water replenishment tank replenishes the water injection pipes. This system achieves step-by-step recovery and tiered utilization of waste heat from the injection molding process, improving the stability of the material feeding subsystem and reducing the energy and water consumption of the cooling subsystem.

[0051] The technical solutions of this application and how they solve the aforementioned technical problems are described in detail below with specific embodiments. These specific embodiments can be implemented independently or in combination with each other. Identical or similar concepts or processes may not be repeated in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0052] Figure 1 This is a schematic diagram illustrating a scenario for the waste heat recovery system of the injection molding process provided in this application. It should be noted that... Figure 1 The examples shown are merely examples of application scenarios for the cooling waste heat utilization system of the injection molding process of this application, in order to help those skilled in the art understand the technical content of this application, but do not mean that the embodiments of this application cannot be used in other equipment, systems, environments or scenarios.

[0053] like Figure 1 As shown, the waste heat recovery system for the injection molding process includes: material feeding subsystem 1, injection molding subsystem 2, cooling subsystem 3, and waste heat recovery subsystem 4.

[0054] The feeding subsystem 1 is used to supply plastic raw materials to the injection molding subsystem 2. The injection molding subsystem 2 is used to perform injection molding on the plastic raw materials. The cooling subsystem 3 absorbs the heat generated by the injection molding subsystem 2 during the injection molding process and transfers the heat to the waste heat utilization subsystem 4. The waste heat utilization subsystem 4 recovers the heat and then supplies the heat back to the feeding subsystem 1 to achieve waste heat recovery and reuse.

[0055] The waste heat utilization subsystem 4 includes an air compressor 41 and a surface heat exchanger 42. The surface heat exchanger 42 is a heat exchange device that heats the air by having a heat transfer medium flow through the inner cavity of a metal pipe and the air to be processed flow through the outer wall of the metal pipe for heat exchange. The surface heat exchanger 42 can be, for example, one or more heat exchange modules that include coolers, coils, and other equipment.

[0056] The surface heat exchanger 42 is connected to the injection molding subsystem 2 and the cooling subsystem 3 respectively through water injection pipes for waste heat recovery. The cooling subsystem 3 and the injection molding subsystem 2 are connected through water injection pipes. The circulating cooling water in the cooling subsystem 3 absorbs the heat generated by the injection molding subsystem 2 during the injection process through the water injection pipes, and the absorbed heat is transported to the surface heat exchanger 42 in the waste heat utilization subsystem 4 through the water injection pipes for heat exchange. After the heat exchange is completed, the water is returned to the cooling subsystem 3 through the water injection pipes, forming a heat exchange cycle.

[0057] The surface heat exchanger 42 is used to absorb the low-grade and high-grade waste heat generated by the injection molding subsystem 2, and to use the absorbed waste heat to heat the compressed air generated by the air compressor 41. The air compressor 41 is connected to the material supply subsystem 1 through an air pipe so that the heated compressed air can be supplied to the material supply subsystem 1 through the air pipe.

[0058] The waste heat recovery system for the injection molding process provided in this embodiment absorbs the heat generated by the injection molding subsystem during the injection molding process through a cooling subsystem and transports the heat to the waste heat recovery subsystem through a water injection pipe. The waste heat recovery subsystem recovers the heat through a surface heat exchanger and then heats the compressed air generated by the air compressor before supplying the heated air to the material supply subsystem through an air pipe. This allows the material supply subsystem to provide plastic raw materials to the injection molding subsystem, which then performs the injection molding process on the plastic raw materials. This system realizes the recovery and reuse of waste heat from the injection molding process, improves the stability of the material supply subsystem, and reduces the energy and water consumption of the cooling subsystem.

[0059] For example, the waste heat utilization subsystem also includes: a first plate heat exchanger.

[0060] Figure 2 This embodiment provides a schematic diagram of the cooling waste heat recovery system for the injection molding process. Figure 1 ,like Figure 2 As shown, the waste heat utilization subsystem 4 includes an air compressor 41, a surface heat exchanger 42, and a first plate heat exchanger 43.

[0061] The first plate heat exchanger 43 is connected to the cooling subsystem 3, the injection molding subsystem 2 and the surface heat exchanger 42 through water injection pipes. The first plate heat exchanger 43 is used to absorb the low-grade waste heat generated by the injection molding subsystem 2 and the high-grade waste heat generated by the injection molding subsystem 2, and transfer the high-grade waste heat and the low-grade waste heat to the surface heat exchanger 42 through the water injection pipes.

[0062] Among them, the first plate heat exchanger 43 is a plate heat exchanger. The plate heat exchanger is a high-efficiency heat exchanger made up of a series of corrugated metal plates stacked together. Thin rectangular channels are formed between the various plates. The fluid working medium flows through the rectangular channel between two plates. The hot and cold fluids pass through the flow channel in sequence. There is a partition plate in the middle to separate the fluids and exchange heat through this plate. It has the characteristics of high heat exchange efficiency, low heat loss, compact and lightweight structure, small footprint, wide application and long service life.

[0063] Understandably, low-grade waste heat refers to waste heat resources that are of low grade, low in energy, and difficult to recover and reuse, i.e., waste heat resources with low temperatures. High-grade waste heat refers to waste heat resources that have high workability, i.e., waste heat resources with high temperatures. During the injection molding process, the waste heat generated by different components and equipment within the injection molding subsystem 2 has different grades. Therefore, the waste heat generated by the injection molding subsystem 2 includes both high-grade and low-grade waste heat.

[0064] Cooling subsystem 3 provides circulating cooling water to the injection molding subsystem. After absorbing the low-grade waste heat and high-grade waste heat generated by injection molding subsystem 2, the circulating cooling water in injection molding subsystem 2 rises in temperature and enters the hot side of the first plate heat exchanger 43 through the water injection pipe to release heat. Then, it flows back to cooling subsystem 3 through the water injection pipe after injection molding subsystem 2 for cooling and then enters injection molding subsystem 2 for circulating cooling. This is done to control the temperature of the injection molding subsystem to be kept within a reasonable temperature range and ensure the best injection molding effect.

[0065] The cooling subsystem 3 also provides circulating cooling water to the cold side of the first plate heat exchanger. When the circulating cooling water in the cooling subsystem 3 enters the cold side of the first plate heat exchanger 43 through the water injection pipe, it exchanges heat with the hot side of the first plate heat exchanger 43, that is, it absorbs the low-grade waste heat and high-grade waste heat generated by the injection molding subsystem 2, causing the temperature of the circulating cooling water to rise. After the waste heat recovery is completed, the high-grade waste heat and low-grade waste heat are transferred together to the surface heat exchanger 42 through the water injection pipe for reuse. Therefore, the waste heat recovery level of the first plate heat exchanger is a two-stage plate heat exchanger.

[0066] The waste heat recovery system for the injection molding process provided in this embodiment utilizes a first plate heat exchanger within the waste heat recovery subsystem. This first plate heat exchanger absorbs both low-grade and high-grade waste heat generated by the injection molding subsystem. The high-grade and low-grade waste heat are then transferred together to a surface heat exchanger via a water injection pipe. After recovering heat, the surface heat exchanger heats the compressed air generated by the air compressor and then supplies the heated air to the material supply subsystem via an air pipe. This allows the material supply subsystem to provide plastic raw materials to the injection molding subsystem, which then performs injection molding on the plastic raw materials. This system achieves waste heat recovery and reuse in the injection molding process, improves the stability of the material supply subsystem, and reduces the energy and water consumption of the cooling subsystem.

[0067] For example, the waste heat utilization subsystem includes: a first plate heat exchanger and a second plate heat exchanger.

[0068] Figure 3 This embodiment provides a schematic diagram of the cooling waste heat recovery system for the injection molding process. Figure 2 ,like Figure 3 As shown, the waste heat utilization subsystem 4 includes: an air compressor 41, a surface heat exchanger 42, a first plate heat exchanger 43, and a second plate heat exchanger 44. The first plate heat exchanger 43 is connected to the injection molding subsystem 2, the second plate heat exchanger 44, and the surface heat exchanger 42 via water injection pipes. The second plate heat exchanger 44 is connected to the injection molding subsystem 2 and the cooling subsystem 3 via water injection pipes.

[0069] The second plate heat exchanger 44 is used to absorb the low-grade waste heat generated by the injection molding subsystem 2 and transfer the low-grade waste heat to the first plate heat exchanger 43 through a water injection pipe. The cooling subsystem 3 provides circulating cooling water to the cold side of the second plate heat exchanger 44 through the water injection pipe, so that the circulating cooling water on the cold side can absorb the heat from the hot side of the second plate heat exchanger 44, i.e., the low-grade waste heat generated by the injection molding subsystem 2. Therefore, the waste heat recovery level of the second plate heat exchanger 44 is that of a first-stage plate heat exchanger.

[0070] The first plate heat exchanger 43 is used to absorb the high-grade waste heat generated by the injection molding subsystem 2, and to transfer the high-grade waste heat and the low-grade waste heat transmitted by the second plate heat exchanger 44 to the surface heat exchanger 42 through the water injection pipe.

[0071] The cooling subsystem 3 provides circulating cooling water to the injection molding subsystem 2 and the waste heat utilization subsystem 4 via water injection pipes. The circulating cooling water in the injection molding subsystem 2 absorbs the high-grade waste heat generated by the injection molding subsystem 2 and then transports this high-grade waste heat to the hot side of the first plate heat exchanger 43. The cold side of the second plate heat exchanger 44, through water injection pipes, transports the low-grade waste heat absorbed by the injection molding subsystem 2 to the cold side of the first plate heat exchanger 43 for heat exchange. The absorbed high-grade waste heat and the low-grade waste heat transferred by the second plate heat exchanger 44 are then jointly transferred through water injection pipes to the surface heat exchanger 42. This allows the surface heat exchanger 42 to use the absorbed waste heat to heat the compressed air generated by the air compressor 41, and the heated compressed air is then supplied to the material supply subsystem 1 through the air pipes.

[0072] The waste heat recovery system for the injection molding process provided in this embodiment utilizes a second plate heat exchanger and a first plate heat exchanger within the waste heat recovery subsystem. The second plate heat exchanger absorbs low-grade waste heat generated by the injection molding subsystem and transfers it to the first plate heat exchanger. The first plate heat exchanger absorbs high-grade waste heat generated by the injection molding subsystem and transfers the high-grade waste heat and the low-grade waste heat transferred from the second plate heat exchanger to a surface heat exchanger via a water injection pipe. After recovering heat, the surface heat exchanger heats the compressed air generated by the air compressor and then supplies the heated air to the material supply subsystem via an air pipe. This allows the material supply subsystem to provide plastic raw materials to the injection molding subsystem, which then performs injection molding on the plastic raw materials. This system achieves the step-by-step recovery and reuse of waste heat from the injection molding process, improves the stability of the material supply subsystem, and reduces the energy and water consumption of the cooling subsystem.

[0073] For example, the injection molding subsystem includes: a first cooling tower, an injection molding machine, and an injection mold.

[0074] Figure 4 This embodiment provides a schematic diagram of the cooling waste heat recovery system for the injection molding process. Figure 3 ,exist Figure 2 and Figure 3 Based on the embodiments shown, the cooling waste heat utilization system for the injection molding process provided in this application will be further described.

[0075] like Figure 4 As shown, the injection molding subsystem 2 includes: a first cooling tower 21, an injection molding machine 22, and an injection mold 23. The first cooling tower 21 is connected to the first plate heat exchanger 43 and the injection molding machine 22 via water injection pipes. The first cooling tower 21 is used to cool the heat generated by the injection molding machine 22 during operation.

[0076] The injection molding machine 22 is connected to the first plate heat exchanger 43 via a water injection pipe. The circulating cooling water corresponding to the injection molding machine 22 absorbs the high-grade waste heat generated by the injection molding machine 22. The circulating cooling water enters the hot side of the first plate heat exchanger 43 to release heat, so that the cold side of the first plate heat exchanger 43 absorbs the high-grade waste heat and merges with the low-grade waste heat absorbed by the cold side of the second plate heat exchanger 44 from the injection molding subsystem 2. After being cooled by the first cooling tower 21, it enters the injection molding machine 22, so that the circulating cooling water can continue to absorb the high-grade waste heat generated by the injection molding machine 22, thereby forming a circulating cooling process.

[0077] Understandably, the high-grade waste heat generated by the injection molding machine 22 is, for example, the waste heat of the hydraulic oil. The injection molding machine 22 is a molding equipment that uses plastic molds to form plastic products of various shapes from thermoplastic or thermosetting plastic raw materials. When the injection molding machine 22 is working, it needs to use the hydraulic oil circuit. When the oil is squeezed, the oil temperature will rise as the hydraulic device continues to work, resulting in a significant decrease in oil viscosity, increased leakage, and damage to the oil film in various sliding parts, which will aggravate the wear of hydraulic components. Therefore, the waste heat of the hydraulic oil is a high-grade waste heat that can be recovered. Recovering the waste heat of the hydraulic oil generated by the injection molding machine 22 can achieve the effect of cooling the hydraulic oil circuit of the injection molding machine 22.

[0078] The first cooling tower 21 utilizes the contact between circulating cooling water and air flow to exchange heat and generate steam. The steam evaporates and releases heat into the atmosphere, thereby reducing the water temperature through evaporative cooling.

[0079] The injection mold 23 is connected to the cooling subsystem 3 and the second plate heat exchanger 44 via water injection pipes. The injection mold 23 is a tool used in the injection molding process to produce products of a specific shape and size. The injection mold 23 has a great influence on the quality of the injection molded parts because it generates a lot of heat during the injection process. If it is not cooled in time, it will cause problems such as deformation, shrinkage or cracking of the injection molded parts. Therefore, the injection mold 23 can be circulated and cooled by the cooling subsystem 3 and the second plate heat exchanger 44.

[0080] For example, the cooling subsystem 3 provides circulating cooling water to the injection mold 23. The circulating cooling water enters the interior of the injection mold 23 through the water injection pipe and absorbs heat by contacting the surface of the injection mold 23 and the surface of the injection part. The low-grade residual heat generated by the injection mold 23 is then transported to the hot side of the second plate heat exchanger 44 through the water injection pipe for heat release. The circulating cooling water then flows back to the cooling subsystem 3 through the water injection pipe. After the cooling subsystem 3 cools the circulating cooling water, it provides circulating cooling water to the cold side of the second plate heat exchanger 44 through the water injection pipe. This allows the circulating cooling water to absorb low-grade residual heat, i.e., the heat generated by the injection mold 23, on the cold side of the second plate heat exchanger 44, in a continuous cycle, thereby achieving the cooling of the injection mold 23 during the injection process.

[0081] The low-grade waste heat generated by the injection mold 23 is transported to the cold side of the first plate heat exchanger 43 via circulating cooling water to absorb the high-grade waste heat corresponding to the hot side of the first plate heat exchanger 43. The low-grade waste heat and the high-grade waste heat are then combined and fed into the surface heat exchanger 42 to achieve the step-by-step recovery of waste heat.

[0082] Optionally, in injection molding subsystem 2, both injection mold 23 and injection molding machine 22 adopt closed-loop cooling water systems and are independent of each other. Injection mold 23 can be a single mold or multiple molds in production.

[0083] Optionally, the number of injection molding machines 22 can be one or more, that is, the injection molding machine 22 can be a single injection molding machine or multiple injection molding machines in the workshop.

[0084] For example, the material feeding subsystem includes a centralized material feeding system and an injection molding machine hopper.

[0085] Continue to refer to Figure 4 ,like Figure 4 As shown, the material feeding subsystem 1 includes a centralized material feeding system 11 and an injection molding machine hopper 12.

[0086] The centralized feeding system 11 is connected to the air compressor 41 and the injection molding machine hopper 12 through air pipes. The compressed air generated by the air compressor 41, after being heated, is used to heat the storage tank and air conveying pipe in the centralized feeding system 11 through the air pipes, and to pre-dehumidify and dry the injection molding machine hopper 12.

[0087] The air compressor 41 is used to generate compressed air and deliver the compressed air to the surface heat exchanger 42 through the air pipeline to absorb the high-grade waste heat and low-grade waste heat generated by the injection molding subsystem 2 in the surface heat exchanger 42. After heat exchange with the surface heat exchanger 42, the compressed air is heated and delivered to the centralized feeding system 11 through the air pipeline.

[0088] When there are multiple injection molding machines 22 in the injection molding subsystem 2, the centralized feeding system 11 includes common equipment and pipelines for distributing and conveying plastic raw materials to the multiple injection molding machines. The injection molding machine hopper 12 refers to the device used to store the granular plastic raw materials of the injection molding machines 22. Therefore, the heated compressed air can heat the storage tank and air conveying pipeline in the centralized feeding system 11 to dry the injection molding raw materials; and the dry hot air obtained after heat exchange with the surface heat exchanger is also transported to the injection molding machine hopper 12 through the air pipeline to pre-dehumidify and dry the plastic raw materials in the injection molding machine hopper 12.

[0089] The utilization of the cooling waste heat of the injection molding subsystem 2 by the material supply subsystem 1 is the first-level cascade utilization of the cooling waste heat utilization system of the injection molding process provided in this embodiment. By utilizing the cooling waste heat of the injection molding subsystem 2 in the first-level cascade utilization, the stability of the material supply subsystem 2 can be improved and the energy and water consumption of the cooling subsystem 3 can be reduced.

[0090] For example, the cooling subsystem includes: a second cooling tower, a first chiller, and a second chiller.

[0091] Continue to refer to Figure 4 ,like Figure 4 As shown, the cooling subsystem 3 includes: a second cooling tower 32, a first chiller 33, and a second chiller 31.

[0092] The second cooling tower 32 is connected to the first chiller 33 and the second chiller 31 respectively through water injection pipes. The second cooling tower 32 is used to cool the circulating cooling water in the first chiller 33 and the second chiller 31. The second cooling tower 32 generates steam by exchanging heat between the circulating cooling water and the air flow. The steam evaporates and releases the heat into the atmosphere, thereby reducing the water temperature through evaporative cooling.

[0093] The first chiller 33 and the second plate heat exchanger 44 are connected by a water injection pipe. Therefore, after the surface heat exchanger 42 releases its waste heat, the circulating cooling water flows back to the first chiller 33 through the water injection pipe. The first chiller 33 cools the circulating cooling water and then sends it to the cold side inlet of the second plate heat exchanger 44 through the water injection pipe to absorb the heat from the circulating cooling water on the hot side of the second plate heat exchanger 44.

[0094] The second chiller 31 is connected to the second plate heat exchanger 44 and the injection mold 23 via water injection pipes. The second chiller 31 is used to cool the heat generated by the injection mold 23 during the injection molding process. During injection molding, a water pump draws circulating cooling water from the second chiller 31, which enters the interior of the injection mold 23 through the water injection pipes. The circulating cooling water absorbs heat by contacting the surfaces of the injection mold 23 and the molded part, and the low-grade heat absorbed by the circulating cooling water is transferred to the hot side of the second plate heat exchanger 44. This allows the circulating cooling water from the first chiller 33 to the cold side of the second plate heat exchanger 44 to exchange heat with the low-grade waste heat on the hot side. The water then flows back to the second chiller 31 through the water injection pipes, repeating the cycle to cool the injection mold 23 during the injection molding process. The second chiller 31 is used to produce low-temperature chilled water and is connected to the second cooling tower 32 via water injection pipes. Therefore, the circulating cooling water can be further circulated and cooled through the second cooling tower 32.

[0095] Understandably, after the circulating cooling water completes heat exchange through the surface heat exchanger 42, it flows back to the first chiller 33 through the water injection pipe for cooling, and then circulates into the cold side of the second plate heat exchanger 44 to form a closed-loop cooling water circuit.

[0096] For example, the cooling subsystem also includes: at least one water pump, continuing to refer to Figure 4 ,like Figure 4 As shown, the second cooling tower 32 is also connected to the first plate heat exchanger 43 through a water injection pipe. When the inlet water temperature of the second cooling tower 32 is higher than the outlet water temperature of the first plate heat exchanger 43, at least one water pump (not shown in the figure) is used to inject water into the first plate heat exchanger 43 through the water injection pipe.

[0097] Understandably, the second cooling tower 32 is used to indirectly exchange heat with air to discharge heat into the atmosphere, thereby lowering the water temperature. Therefore, when the outdoor temperature is high, the temperature of the circulating cooling water in the second cooling tower 32 is also high. When the inlet water temperature of the second cooling tower 32 is higher than the outlet water temperature of the first plate heat exchanger 43, a water pump can be used to extract a portion of the circulating cooling water at the inlet of the second cooling tower 32 and mix it with the cold-side outlet water of the first plate heat exchanger 43. This mixture is then transported to the surface heat exchanger 42 through a water injection pipe to recover the heat from the circulating cooling water at the inlet of the second cooling tower 32 and reduce the energy and water consumption of the cooling subsystem 3. For example, when the inlet water temperature of the second cooling tower 32 is 3-5°C higher than the outlet water temperature of the first plate heat exchanger 43, the water pump can be controlled to extract the circulating cooling water at the inlet of the second cooling tower 32.

[0098] For example, the waste heat utilization subsystem also includes: hot water load.

[0099] Continue to refer to Figure 4 ,like Figure 4 As shown, the waste heat utilization subsystem 4 also includes a hot water load 45. The surface heat exchanger 42 is connected to the hot water load 45 via a water injection pipe. The surface heat exchanger 42 is also used to provide heat to the hot water load 45 using the absorbed waste heat. The surface heat exchanger 42 provides hot water to the hot water load 45 via the water injection pipe. The hot water load 45 is used to supply hot water to the surrounding factory or workshop. Besides supplying the absorbed waste heat from the injection molding subsystem to the material feeding subsystem 1, the surface heat exchanger 42 can also provide waste heat to the hot water load 45 in the waste heat utilization subsystem 4. Therefore, the utilization of cooling waste heat by the hot water load 45 is the second-stage cascade utilization of the cooling waste heat utilization system for the injection molding process provided in this embodiment.

[0100] For example, the waste heat utilization subsystem further includes a water replenishment tank.

[0101] Continue to refer to Figure 4 ,like Figure 4 As shown, the waste heat utilization subsystem includes: an air compressor 41, a surface heat exchanger 42, a second plate heat exchanger 44, a first plate heat exchanger 43, a primary hot water load 45, and a water supply tank 46.

[0102] The surface heat exchanger 42 is connected to the water supply tank 46 via a water supply pipe. The water supply tank 46 is used to replenish the water supply pipe when the flow rate of the circulating water in the water supply pipe decreases.

[0103] Understandably, the surface heat exchanger 42 absorbs waste heat from the injection molding subsystem 2 and releases it to heat the compressed air generated by the air compressor 41. The heated compressed air is then supplied to the centralized feeding system 11 and the injection molding machine hopper 12 via air ducts, representing the first stage of waste heat utilization. After the waste heat from the first stage is cooled by heat release, the surface heat exchanger 42 provides hot water to the hot water load 45, achieving the second stage of waste heat utilization. Consequently, the amount of circulating cooling water in the cooling subsystem 3 decreases, requiring replenishment through the water tank 46. After replenishment, the circulating cooling water re-enters the first chiller 33 for cooling before circulating back to the cold side of the second plate heat exchanger 44.

[0104] The waste heat recovery system for the injection molding process provided in this embodiment absorbs low-grade waste heat generated by the injection mold through a second plate heat exchanger and transfers it to a first plate heat exchanger. The first plate heat exchanger absorbs high-grade waste heat generated by the injection molding machine and transfers both high-grade and low-grade waste heat to a surface heat exchanger through a water injection pipe. Furthermore, when the inlet water temperature of the second cooling tower is higher than the outlet water temperature of the first plate heat exchanger, a water pump draws circulating cooling water from the inlet of the second cooling tower through the water injection pipe and mixes it with the outlet water from the cold side of the first plate heat exchanger. The waste heat is transferred to a surface heat exchanger, which recovers heat and heats the compressed air generated by the air compressor. The heated air is then supplied to the centralized feeding system and the injection molding machine hopper through air pipes, achieving the first stage of waste heat recovery. The remaining waste heat from the surface heat exchanger is supplied to the hot water load, achieving the second stage of waste heat recovery. Water is replenished to the water injection pipe through a water tank. This system realizes the step-by-step recovery and tiered utilization of waste heat in the injection molding process, improves the stability of the feeding subsystem, and reduces the energy and water consumption of the cooling subsystem.

[0105] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts among the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the system embodiments, so the description is relatively simple; refer to the description of the system embodiments for relevant parts. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0106] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0107] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A system for utilizing cooling waste heat in an injection molding process, characterized in that, The waste heat recovery system includes: a material feeding subsystem, an injection molding subsystem, a cooling subsystem, and a waste heat recovery subsystem, wherein the waste heat recovery subsystem includes: an air compressor and a surface heat exchanger; The surface heat exchanger is connected to the injection molding subsystem and the cooling subsystem respectively via water injection pipes; The air compressor is connected to the feeding subsystem via an air duct; The surface heat exchanger is used to absorb the low-grade and high-grade waste heat generated by the injection molding subsystem, and uses the absorbed waste heat to heat the compressed air generated by the air compressor, so that the heated compressed air is supplied to the material supply subsystem through the air pipeline. The feeding subsystem is used to supply plastic raw materials to the injection molding subsystem, and the injection molding subsystem is used to perform injection molding on the plastic raw materials; The waste heat utilization subsystem includes: a first plate heat exchanger and a second plate heat exchanger; The first plate heat exchanger is connected to the injection molding subsystem, the second plate heat exchanger, and the surface heat exchanger via water injection pipes. The second plate heat exchanger is connected to the injection molding subsystem and the cooling subsystem respectively via water injection pipes; The second plate heat exchanger is used to absorb the low-grade waste heat generated by the injection molding subsystem and transfer the low-grade waste heat to the first plate heat exchanger through the water injection pipe. The first plate heat exchanger is used to absorb the high-grade waste heat generated by the injection molding subsystem, and to transfer the high-grade waste heat and the low-grade waste heat transmitted by the second plate heat exchanger to the surface heat exchanger through the water injection pipe.

2. The system according to claim 1, characterized in that, The injection molding subsystem includes: a first cooling tower, an injection molding machine, and an injection mold; The first cooling tower is connected to the first plate heat exchanger and the injection molding machine respectively through water injection pipes. The first cooling tower is used to cool the heat generated by the injection molding machine during operation. The injection molding machine is connected to the first plate heat exchanger via a water injection pipe; The injection mold is connected to the cooling subsystem and the second plate heat exchanger via water injection pipes.

3. The system according to claim 2, characterized in that, The material supply subsystem includes: a centralized material supply system and an injection molding machine hopper; The centralized material supply system is connected to the air compressor and the injection molding machine hopper via air pipes. The compressed air generated by the air compressor, after being heated, is used to heat the storage tank and air delivery pipe in the centralized material supply system and to pre-dehumidify and dry the injection molding machine hopper via the air pipes.

4. The system according to claim 3, characterized in that, The cooling subsystem includes: a second cooling tower, a first chiller, and a second chiller; The second cooling tower is connected to both the first chiller and the second chiller via the water injection pipe; The first chiller and the second plate heat exchanger are connected via the water injection pipe; The second chiller is connected to the second plate heat exchanger and the injection mold via the water injection pipe.

5. The system according to claim 4, characterized in that, The cooling subsystem also includes: at least one water pump; The second cooling tower is also connected to the first plate heat exchanger through the water injection pipe. The second cooling tower is used to inject water into the first plate heat exchanger through the water injection pipe when the inlet water temperature of the second cooling tower is higher than the outlet water temperature of the first plate heat exchanger.

6. The system according to claim 1, characterized in that, The waste heat utilization subsystem also includes: hot water load; The surface heat exchanger is connected to the hot water load via a water injection pipe, and the surface heat exchanger is also used to provide heat to the hot water load using the absorbed waste heat.

7. The system according to claim 6, characterized in that, The waste heat utilization subsystem also includes: a water supply tank; The surface heat exchanger is connected to the water supply tank via a water supply pipe. The water supply tank is used to replenish the water supply pipe when the flow rate of the circulating water in the water supply pipe decreases.

8. The system according to claim 3, characterized in that, The number of injection molding machines is one or more.

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