System and method for recovering waste heat of condensate water of tobacco shred production line

Abstract

The invention belongs to the technical field of condensate water recovery systems, and provides a silk thread production line condensate water waste heat recovery system and a recovery method thereof.The system comprises a steam treatment unit, an air treatment unit, a heat exchange unit, a condensate water recovery unit and a mixing unit; the air processing unit comprises a first-stage hot air heat exchanger and a second-stage hot air heat exchanger which are connected through a pipeline. The mixing unit is used for recycling high-temperature condensate water and first low-temperature condensate water discharged by the steam treatment unit, the air treatment unit and the heat exchange unit and conveying the high-temperature condensate water into the first-stage hot air heat exchanger so as to preheat air in the high-temperature condensate water, and hot air and second low-temperature condensate water are obtained; the first-stage hot air heat exchanger discharges the second low-temperature condensed water into the condensed water recovery unit through a pipeline, and the mixing unit discharges the first low-temperature condensed water into the condensed water recovery unit through a pipeline. On the basis that secondary steam is eliminated, waste heat contained in the high-temperature condensate water can be recycled for the second time.

Description

Technical Field

[0001] The present application relates to the technical field of condensate recovery systems, and in particular to a silk thread condensate waste heat recovery system and a recovery method thereof. Background Art

[0002] In the existing tobacco production lines in cigarette factories, both the loosening and moistening machine and the thin plate drying machine for tobacco use saturated steam as the heat source required by the equipment. Among them, the loosening and moistening machine usually uses two hot air heat exchangers to provide hot air for the equipment, while the thin plate drying machine uses one hot air heat exchanger to heat the required hot air, and directly heats the thin plate in its drum through saturated steam.

[0003] However, in the existing process and condensate recovery system of the silk-making line (see Appendix Figure 1 After saturated steam completes a primary heat exchange in a hot air heat exchanger or thin plate heat exchanger, the resulting condensate is directly discharged through a steam trap into the condensate recovery network and recycled back to the power plant. Due to the relatively high temperature requirements of hot air heat exchangers and thin plate heat exchangers (typically 110°C to 150°C), the discharged condensate remains at temperatures as high as 100°C to 110°C, containing a significant amount of waste heat that is not recovered. In this case, the high-temperature condensate is prone to generating secondary steam during the recovery and transportation process, resulting in excessive back pressure in the condensate recovery network and low condensate recovery stability, affecting the operating efficiency of the entire recovery system. This situation can also hinder the recovery of some of the lower-temperature condensate from the silk-making line, leading to energy waste.

[0004] To reduce energy waste, those skilled in the art have continuously improved condensate recovery systems. For example, patent application publication number CN116147373A discloses a steam condensate recovery system for a silk-making workshop, comprising a thin-plate silk-making machine, a main equipment group, a condensate tank, a third water pump, and a power workshop boiler room. Condensate generated by the thin-plate silk-making machine and the main equipment group is transported to the condensate tank via a first pipeline and a second pipeline, respectively. The condensate tank supplies condensate to the main equipment via a water supply pipeline. The condensate tank is connected to the power workshop boiler room via a third pipeline, and a third water pump is disposed on the third pipeline, pumping water from the condensate tank into the power workshop boiler room. The power workshop boiler room can produce soft water, which is transported to the condensate tank via a fourth pipeline. However, the main purpose of this system is to solve the problems of poor condensate discharge and condensate backflow, and it still cannot solve the problem of waste heat recovery from high-temperature condensate.

[0005] For example, patent publication number CN217686699U discloses a closed condensate recovery system, comprising first and second condensate recovery tanks connected at the bottom. The first tank's inlet is connected to the condensate pipe of a thin-sheet tofu drying machine, while the second tank is connected to a low-temperature cooling water pipe equipped with an electric regulating valve. The top steam outlet pipe of the first tank is connected to the throat inlet of a first hydraulic jet pump, the nozzle inlet of the first hydraulic jet pump is connected to the side outlet pipe of the second tank equipped with the first water pump, and the diffuser outlet of the first hydraulic jet pump is connected to the top water inlet pipe of the second tank. The bottom outlet pipe of the second tank is connected to the throat inlet of a second hydraulic jet pump, the diffuser outlet of the second hydraulic jet pump is connected to the inlet pipe of the second water pump, and a self-operated pressure regulating valve is installed on the outlet pipe of the second water pump. A return pipe connected to the nozzle inlet of the second hydraulic jet pump is provided between the self-operated pressure regulating valve and the second water pump, and a throttle valve is installed on the return pipe. This system can achieve energy conservation and emission reduction and eliminate secondary steam, but it does not recycle the waste heat of the high-temperature condensate. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a silk thread condensate waste heat recovery system and a recovery method thereof, which can recycle the waste heat contained in the high-temperature condensate on the basis of eliminating secondary steam.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A first aspect of the present invention provides a silk thread condensate waste heat recovery system, comprising a steam treatment unit, an air treatment unit, a heat exchange unit, a condensate recovery unit, and a mixing unit. The air treatment unit comprises a primary hot air heat exchanger and a secondary hot air heat exchanger connected in sequence by pipes along the air flow direction. The heating temperature of the primary hot air heat exchanger is lower than the heating temperature of the secondary hot air heat exchanger.

[0009] The steam treatment unit, the air treatment unit, and the heat exchange unit are respectively connected to the mixing unit pipeline. The mixing unit is used to recover the high-temperature condensed water and the first low-temperature condensed water discharged from the steam treatment unit, the air treatment unit, and the heat exchange unit, and transport the high-temperature condensed water to the first-level hot air heat exchanger to preheat the air therein to obtain hot air and the second low-temperature condensed water;

[0010] The condensed water recovery unit is connected to the first-level hot air heat exchanger and the mixing unit pipeline respectively. The first-level hot air heat exchanger discharges the second low-temperature condensed water into the condensed water recovery unit through the pipeline, and the mixing unit discharges the first low-temperature condensed water into the condensed water recovery unit through the pipeline.

[0011] According to the above technical means, the present application recycles the high-temperature condensed water and the first low-temperature condensed water discharged from the steam treatment unit, the air treatment unit and the heat exchange unit into the mixing unit, and then transports the high-temperature condensed water to the first-level hot air heat exchanger through the mixing unit for energy supply, so as to preheat the room-temperature air absorbed by the front stage of the air treatment unit, and then conducts secondary heating through the second-level hot air heat exchanger so that the heat source temperature generated by it reaches the saturated steam temperature required by the silk thread making equipment. At the same time, the present application discharges the first low-temperature condensed water and the second low-temperature condensed water discharged from the first-level hot air heat exchange into the condensed water recovery unit. At this time, the condensed water temperature is low and no secondary steam is generated, thereby reducing the back pressure of the condensed water recovery unit, so that the low-temperature condensed water can be stably recovered.

[0012] In addition, the system of the present application adopts a series heat exchange structure, combining the mixing unit with an air handling unit with a two-stage heat exchanger to achieve double energy saving while ensuring the system temperature, that is, recovering the waste heat of high-temperature condensed water and using the waste heat to preheat the room temperature air. This solution can improve the utilization rate of thermal energy in the silk thread making process and reduce energy consumption.

[0013] Furthermore, the steam processing unit is connected to the secondary hot air heat exchanger and the heat exchange unit pipeline respectively.

[0014] Furthermore, it also includes a signal-connected flow control unit and a monitoring and feedback unit. The monitoring and feedback unit is used to collect the temperature signal of the air treatment unit, collect the pressure signal in the connecting pipe between the steam treatment unit and the heat exchange unit, and feed back the temperature signal and pressure signal to the flow control unit.

[0015] Furthermore, the flow control unit includes multiple pneumatic diaphragm valves for regulating the flow of condensed water and / or steam in the pipeline, and the multiple pneumatic diaphragm valves are respectively installed on the connecting pipeline between the steam treatment unit and the heat exchange unit, on the connecting pipeline between the steam treatment unit and the secondary hot air heat exchanger, and on the connecting pipeline between the mixing unit and the secondary hot air heat exchanger.

[0016] Furthermore, the monitoring and feedback unit includes a first-level temperature sensor and a second-level temperature sensor. The first-level temperature sensor is electrically connected to the air outlet of the first-level hot air heat exchanger for adjusting the hot air temperature at the air outlet of the first-level hot air heat exchanger; the second-level temperature sensor is electrically connected to the air outlet of the second-level hot air heat exchanger for feedback of the heat source temperature at the air outlet of the second-level hot air heat exchanger.

[0017] Furthermore, the steam processing unit includes a steam pipe network, a manual stop valve, a first filter, and a steam-water separator which are sequentially connected by pipes along the steam flow direction.

[0018] Further, the mixing unit includes a condensed water tank.

[0019] A second aspect of the present invention provides a method for recovering waste heat from condensed water of a silk thread, comprising the following steps:

[0020] Recycling the high-temperature condensed water and the first low-temperature condensed water discharged from the steam processing unit, the air processing unit and the heat exchange unit to the mixing unit;

[0021] The mixing unit transports the high-temperature condensed water to the first-stage hot air heat exchanger of the air handling unit to preheat the air therein to obtain hot air and second-stage low-temperature condensed water;

[0022] The hot air is transported to the secondary hot air heat exchanger of the air handling unit for secondary heating to obtain a heat source;

[0023] The first low-temperature condensed water and the second low-temperature condensed water are transported to a condensed water recovery unit.

[0024] Furthermore, the method also includes: real-time monitoring of the current temperature of the hot air, and if the current temperature is not within the target temperature range, adjusting the flow rate of high-temperature condensed water delivered by the mixing unit to the first-stage hot air heat exchanger to correct the current temperature.

[0025] Furthermore, the method also includes: monitoring the real-time temperature of the heat source, and if the real-time temperature is not within a preset temperature range, adjusting the steam flow rate delivered by the steam processing unit to the secondary hot air heat exchanger to correct the real-time temperature.

[0026] The beneficial technical effects of the present invention are:

[0027] The present invention adopts a series heat exchange structure, combining a mixing unit with an air handling unit having a two-stage heat exchanger. This achieves dual energy conservation while ensuring the system temperature. That is, the waste heat of high-temperature condensed water is recovered and used to preheat room-temperature air. This solution can improve the utilization rate of thermal energy in the silk thread making process and reduce energy consumption.

[0028] The present invention adds a mixing unit to recover and reuse high-temperature condensed water, which can solve the problem of secondary steam generated by direct discharge of high-temperature condensed water into the condensed water recovery network in existing silk thread condensed water recovery equipment, ensure the stability of the system for condensed water recovery, and improve the recovery operation efficiency;

[0029] The present invention is based on a composite control strategy of dual temperature monitoring points, which monitors the hot air temperature of the first-stage hot air heat exchanger and the heat source temperature of the second-stage hot air heat exchanger in real time, and adjusts the real-time steam flow and / or high-temperature condensate flow based on the dual temperatures to adapt to the silk-making line working conditions.

[0030] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present application and, together with the specification, serving to explain the principles of the present application. It is obvious that the drawings described below are merely some embodiments of the present application, and it is possible for a person of ordinary skill in the art to derive other drawings based on these drawings without inventive effort. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the structure of the conventional silk thread condensate recovery system;

[0033] Figure 2 This is a schematic diagram of the structure of the silk thread condensate waste heat recovery system for this application.

[0034] Reference numerals

[0035] 101: Steam pipe network; 102: Manual stop valve; 103: First filter; 104: Steam-water separator; 201: Air pipe network; 202: Second filter; 203: First-stage hot air heat exchanger; 204: Second-stage hot air heat exchanger; 301: Condensate tank; 401: Condensate recovery pipe network; 402: Power plant; 501: Heat exchanger; 601: First-stage temperature sensor; 602: Second-stage temperature sensor; 603: Pressure transmitter; 701: First pneumatic diaphragm valve; 702: Second pneumatic diaphragm valve; 703: Third pneumatic diaphragm valve. DETAILED DESCRIPTION

[0036] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. It should be understood that certain features of the invention (described in the context of separate embodiments for clarity) may also be provided in combination in a single embodiment. Conversely, multiple features of the invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or, where appropriate, in any other described embodiment of the invention. Certain features described in the context of various embodiments will not be considered essential features of those embodiments unless the embodiment is inoperable without those elements. The invention is further described below through specific examples, but it should be noted that the specific process conditions and results described in the examples of the invention are only for illustration of the invention and are not intended to limit the scope of protection of the invention. Any equivalent changes or modifications made in accordance with the spirit and substance of the invention should be included within the scope of protection of the invention.

[0037] The present invention provides a silk thread condensate waste heat recovery system, comprising a steam processing unit, an air processing unit, a heat exchange unit, a condensate recovery unit, and a mixing unit. The air processing unit comprises a primary hot air heat exchanger 203 and a secondary hot air heat exchanger 204 connected in sequence by pipes along the air flow direction. The heating temperature of the primary hot air heat exchanger 203 is lower than the heating temperature of the secondary hot air heat exchanger 204.

[0038] The steam processing unit, the air processing unit, and the heat exchange unit are respectively connected to the mixing unit pipeline. The mixing unit is used to recover the high-temperature condensed water and the first low-temperature condensed water discharged from the steam processing unit, the air processing unit, and the heat exchange unit, and transport the high-temperature condensed water to the first-level hot air heat exchanger 203 to preheat the air therein to obtain hot air and the second low-temperature condensed water;

[0039] The condensed water recovery unit is connected to the first-level hot air heat exchanger 203 and the mixing unit pipeline respectively. The first-level hot air heat exchanger 203 discharges the second low-temperature condensed water into the condensed water recovery unit through the pipeline, and the mixing unit discharges the first low-temperature condensed water into the condensed water recovery unit through the pipeline.

[0040] Further, if Figure 2 As shown, the steam processing unit of the present application includes a steam pipe network 101, a manual stop valve 102, a first filter 103, and a steam-water separator 104, which are connected in sequence along the steam flow direction. The steam pipe network 101 is used to provide high-temperature steam as the initial heat source; the manual stop valve 102 is used to control the on / off of the high-temperature steam flow pipeline and ensure maintenance safety; the first filter 103 is used to remove impurities in the high-temperature steam and protect subsequent equipment; and the steam-water separator 104 is used to separate liquid water (i.e., high-temperature condensate) from the high-temperature steam, ensuring that dry high-temperature steam enters subsequent equipment.

[0041] Further, if Figure 2As shown, the air handling unit of the present application includes an air duct network 201, a second filter 202, a first-stage hot air heat exchanger 203, and a second-stage hot air heat exchanger 204, which are sequentially connected along the air flow direction. The air duct network 201 is used to provide indoor air at a temperature of 25°C to 26°C. The second filter 202 is used to purify the air, remove impurities in the air, and prevent dust and other impurities contained in the air from entering the first-stage hot air heat exchanger 203. The first-stage hot air heat exchanger 203 is used to preheat the air to increase its temperature before entering the second-stage hot air heat exchanger 204. In the present application, the preheating temperature of the first-stage hot air heat exchanger 203 is approximately 50°C. The second-stage hot air heat exchanger 204 is used to secondary heat the hot air generated by the first-stage hot air heat exchanger 203 to a temperature of 110°C to 130°C, thereby generating a heat source for entering silk thread making equipment, such as a loosening and rehydrating machine or a thin plate drying machine, to provide saturated steam for heat exchange with tobacco sheets or shredded tobacco in the equipment.

[0042] Further, if Figure 2 As shown, the mixing unit of the present application includes a condensate tank 301, which recovers high-temperature condensate and first-low-temperature condensate. Since condensate of different temperatures naturally forms temperature stratification, high-temperature condensate (over 100°C) due to its lower density accumulates in the upper portion of the condensate tank 301, while first-low-temperature condensate (below 100°C) due to its higher density settles in the lower portion of the condensate tank 301. Therefore, the outlet of the delivery pipe for high-temperature condensate is connected to the upper portion of the condensate tank 301 to lead to the primary hot air heat exchanger 203, and the outlet of the delivery pipe for first-low-temperature condensate is connected to the lower portion of the condensate tank 301 to lead to the condensate recovery unit.

[0043] Further, if Figure 2 As shown, the heat exchange unit of the present application includes a heat exchanger 501, which can be a circulating air heat exchanger or a thin plate heat exchanger.

[0044] Further, if Figure 2 As shown, the condensate recovery unit of the present application includes a condensate recovery network 401 and a power plant 402, which are connected by pipes in sequence along the condensate recovery direction. Among them, the condensate recovery network 401 is used to collect the second low-temperature condensate and the first low-temperature condensate after heat exchange and return them to the power plant 402 for recycling, thereby reducing energy waste.

[0045] Furthermore, the present application recycles the high-temperature condensate and the first low-temperature condensate discharged from the steam-water separator 104, the secondary hot air heat exchanger 204 and the circulating air heat exchanger or the thin-plate heat exchanger into the condensate tank 301, and then transports the high-temperature condensate to the first-level hot air heat exchanger 203 via the condensate tank 301 for energy supply (a hot water pump is installed in the connecting pipe between the condensate tank 301 and the first-level hot air heat exchanger 203, not shown in the figure), so as to preheat the indoor air filtered by the second filter 202 to about 50°C, and then perform secondary heating to 110°C~130°C through the secondary hot air heat exchanger 204, so that the heat source temperature generated by it reaches the saturated steam temperature required by the silk thread making equipment. At the same time, the present application discharges the first low-temperature condensed water and the second low-temperature condensed water discharged from the first-level hot air heat exchange into the condensed water recovery pipe network 401. At this time, the first low-temperature condensed water and the second low-temperature condensed water (both with a temperature less than 100°C) are at a low temperature and will not generate secondary steam, thereby reducing the back pressure of the condensed water recovery pipe network 401 and allowing the low-temperature condensed water to be stably recovered. Furthermore, the system of the present application adopts a series heat exchange structure, combining the condensed water tank 301 with the first-level hot air heat exchanger 203 and the second-level hot air heat exchanger 204. While ensuring the system temperature, dual energy conservation is achieved, namely, the waste heat of the high-temperature condensed water is recovered and the waste heat is used to preheat the room temperature air. This solution can improve the utilization rate of thermal energy in the silk thread making process and reduce energy consumption.

[0046] Furthermore, if Figure 2 As shown, the steam processing unit is connected to the secondary hot air heat exchanger 204 and the heat exchange unit pipeline. Specifically, the steam-water separator 104 of the present application is connected to the secondary hot air heat exchanger 204 pipeline, the steam-water separator 104 is connected to the condensed water tank 301 pipeline, and the steam-water separator 104 is connected to the circulating air heat exchanger or thin plate heat exchanger pipeline.

[0047] Furthermore, if Figure 2 As shown, the system of the present application also includes a monitoring and feedback unit, which includes a primary temperature sensor 601, a secondary temperature sensor 602 and a pressure transmitter 603, wherein the primary temperature sensor 601 is electrically connected to the air outlet of the primary hot air heat exchanger 203, and is used to adjust the hot air temperature at the air outlet of the primary hot air heat exchanger 203; the secondary temperature sensor 602 is electrically connected to the air outlet of the secondary hot air heat exchanger 204, and is used to feedback the heat source temperature at the air outlet of the secondary hot air heat exchanger 204; the pressure transmitter 603 is used to monitor the pressure in the connecting pipe between the steam-water separator 104 and the circulating air heat exchanger or the thin plate heat exchanger.

[0048] Furthermore, if Figure 2As shown, the system of the present application also includes a flow control unit, which is connected to the monitoring and feedback unit signal. The monitoring and feedback unit is used to collect the temperature signal of the air handling unit and the pressure signal in the pipe connecting the steam handling unit and the heat exchange unit, and feed back the temperature signal and pressure signal to the flow control unit. Furthermore, the flow control unit includes multiple pneumatic diaphragm valves for regulating the flow of condensed water and / or steam in the pipe. Specifically, a first pneumatic diaphragm valve 701 is installed on the connecting pipe between the steam-water separator 104 and the secondary hot air heat exchanger 204, a second pneumatic diaphragm valve 702 is installed on the connecting pipe between the steam-water separator 104 and the circulating air heat exchanger or the thin plate heat exchanger, and a third pneumatic diaphragm valve 703 is installed on the connecting pipe between the condensed water tank 301 and the primary hot air heat exchanger 203. Preferably, the multiple pneumatic diaphragm valves of the present application are all pneumatic diaphragm valves with positioners.

[0049] Further, if Figure 2 As shown, the pressure transmitter 603 of the present application monitors the output pressure of the high-temperature condensate in the pipeline in real time and transmits the pressure signal to the PID controller. After calculation, the PID controller feeds back the pressure signal to the second pneumatic diaphragm valve 702 to adjust its valve opening to control the flow of high-temperature condensate entering the pipeline. The present application utilizes the pressure transmitter 603, PID controller, and second pneumatic diaphragm valve 702 in conjunction to prevent excessive back pressure in the pipeline from causing a decrease in heat exchange efficiency.

[0050] Further, if Figure 2 As shown, the secondary temperature sensor 602 of the present application utilizes a post-feedback function and is linked to a PID controller and the first pneumatic diaphragm valve 701. The secondary temperature sensor 602 monitors the temperature of the heat source at the outlet of the secondary hot air heat exchanger 204 in real time and transmits the temperature signal to the PID controller. The PID controller performs calculations upon receiving the signal and, based on the results, controls the valve opening of the first pneumatic diaphragm valve 701 to control the flow of drying steam entering the pipeline. For example, when the secondary temperature sensor 602 detects that the heat source temperature is higher than the preset temperature required by the equipment, the valve opening value B1 (e.g., 8%) is subtracted from the valve opening value B of the first pneumatic diaphragm valve 701 (e.g., 50%). When the secondary temperature sensor 602 detects that the heat source temperature is lower than the preset temperature required by the equipment, the valve opening value B2 (e.g., 10%) is added to the valve opening value B (e.g., 50%) of the first pneumatic diaphragm valve 701 to ensure that the final heat source temperature is maintained between 110°C and 130°C. Furthermore, the functional relationship between the heat source temperature and the valve opening value of the first pneumatic diaphragm valve 701 of the present application can be verified through multiple experiments.

[0051] Further, if Figure 2As shown, the present application's primary temperature sensor 601 is linked to a PID controller and a third pneumatic diaphragm valve 703. The primary temperature sensor 601 monitors the temperature of the hot air at the outlet of the primary hot air heat exchanger 203 in real time and transmits the temperature signal to the PID controller. The PID controller performs calculations while receiving the signal and controls the opening and closing or valve opening of the third pneumatic diaphragm valve 703 based on the calculation results to control the flow of high-temperature condensate entering the pipeline. For example, when the primary temperature sensor 601 detects that the hot air temperature is higher than the feedforward temperature required by the secondary hot air heat exchanger 204, the third pneumatic diaphragm valve 703 is controlled to close; when the primary temperature sensor 601 detects that the hot air temperature is lower than the feedforward temperature required by the secondary hot air heat exchanger 204, the third pneumatic diaphragm valve 703 is controlled to open and its valve opening is adjusted based on the calculation results of the PID controller. Furthermore, the functional relationship between the hot air temperature and the valve opening value of the third pneumatic diaphragm valve 703 in the present application can be verified through multiple experiments.

[0052] Further, if Figure 2 As shown, the low-temperature condensed water in the condensed water recovery network 401 of the present application can also be directly discharged to the outdoors through channels such as on-site trenches.

[0053] The present invention also provides a method for recovering waste heat from condensed water of a silk thread, comprising the following steps:

[0054] Recovering the high-temperature condensed water and the first low-temperature condensed water discharged from the steam processing unit, the air processing unit and the heat exchange unit to the mixing unit;

[0055] The mixing unit transports the high-temperature condensed water to the primary hot air heat exchanger 203 of the air handling unit to preheat the air therein to obtain hot air and the second low-temperature condensed water;

[0056] The hot air is transported to the secondary hot air heat exchanger 204 of the air handling unit for secondary heating to obtain a heat source;

[0057] The first low-temperature condensed water and the second low-temperature condensed water are transported to a condensed water recovery unit.

[0058] Furthermore, the method of the present application can be used to control the above-mentioned silk thread condensate waste heat recovery system.

[0059] Furthermore, the method of the present application also includes real-time monitoring of the current temperature of the hot air. If the current temperature is not within the target temperature range, adjusting the flow rate of high-temperature condensate delivered by the mixing unit to the first-stage hot air heat exchanger 203 to correct the current temperature. Furthermore, the present application adds a first-stage hot air heat exchanger 203 at the air inlet of the second-stage hot air heat exchanger 204 as a preheating device, and achieves precise control of the preheating hot air temperature through a first-stage temperature sensor 601 and a third pneumatic diaphragm valve 703. For example, the first-stage temperature sensor 601 monitors the current temperature of the hot air in real time. If the current temperature is not within the target temperature range (the preheating temperature needs to reach approximately 50°C), the temperature signal is transmitted to a PID controller. The PID controller receives the signal and performs calculations based on the calculation results, controlling the opening and closing or valve opening of the third pneumatic diaphragm valve 703 to control the flow rate of high-temperature condensate entering the pipeline, thereby correcting the current temperature to meet the required preheating hot air temperature.

[0060] Furthermore, the method of the present application also includes monitoring the real-time temperature of the heat source. If the real-time temperature is not within a preset temperature range, adjusting the steam flow rate delivered by the steam processing unit to the secondary hot air heat exchanger 204 to correct the real-time temperature. Furthermore, the heat source of the present application is used to provide saturated steam to equipment such as loose rehumidifiers and thin-plate drying machines for silk thread production to achieve heat exchange for cut tobacco or tobacco sheets. Exemplarily, a secondary temperature sensor 602 monitors the real-time temperature of the heat source and transmits the temperature signal to a PID controller. The PID controller receives the signal and performs calculations based on the calculation results, controlling the valve opening of the first pneumatic diaphragm valve 701 to control the flow rate of drying steam entering the pipeline, thereby correcting the real-time temperature to maintain a preset temperature range (110°C to 130°C).

[0061] Furthermore, the present application used the above method to conduct several experimental tests on the silk-making line condensate waste heat recovery system, and found that the system and method of the present application can increase the utilization rate of the silk-making line condensate waste heat to more than 25%, reduce steam consumption by 10%~20%, and increase the overall system thermal efficiency by more than 25%.

[0062] Furthermore, the present application adds a mixing unit to recycle and reuse high-temperature condensate, which can solve the problem of secondary steam generated by direct discharge of high-temperature condensate into the condensate recovery network 401 in the existing silk thread condensate recovery equipment; and the present application uses the preheating of the first-level hot air heat exchanger 203 to reduce the steam usage of the second-level hot air heat exchanger 204, thereby reducing the amount of steam consumed by the system; the temperature of the second low-temperature condensate after heat exchange in the present application can be reduced to below 80°C, thereby ensuring the stability of the system's condensate recovery and improving the recovery operation efficiency.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A silk thread condensate waste heat recovery system, characterized in that: It comprises a steam processing unit, an air processing unit, a heat exchange unit, a condensed water recovery unit and a mixing unit, wherein the air processing unit comprises a primary hot air heat exchanger (203) and a secondary hot air heat exchanger (204) which are sequentially connected by pipes along the air flow direction, and the heating temperature of the primary hot air heat exchanger (203) is lower than the heating temperature of the secondary hot air heat exchanger (204); The steam processing unit, the air processing unit, and the heat exchange unit are respectively connected to the mixing unit pipeline, and the mixing unit is used to recover the high-temperature condensed water and the first low-temperature condensed water discharged from the steam processing unit, the air processing unit, and the heat exchange unit, and transport the high-temperature condensed water to the first-level hot air heat exchanger (203) to preheat the air therein to obtain hot air and the second low-temperature condensed water; The condensed water recovery unit is respectively connected to the first-stage hot air heat exchanger (203) and the mixing unit pipeline, the first-stage hot air heat exchanger (203) discharges the second low-temperature condensed water into the condensed water recovery unit through the pipeline, and the mixing unit discharges the first low-temperature condensed water into the condensed water recovery unit through the pipeline.

2. The system according to claim 1, wherein: The steam processing unit is respectively connected to the secondary hot air heat exchanger (204) and the heat exchange unit pipeline.

3. The system according to claim 2, characterized in that It also includes a signal-connected flow control unit and a monitoring and feedback unit, wherein the monitoring and feedback unit is used to collect the temperature signal of the air treatment unit, collect the pressure signal in the pipe connecting the steam treatment unit and the heat exchange unit, and feed back the temperature signal and the pressure signal to the flow control unit.

4. The system according to claim 3, characterized in that The flow control unit includes a plurality of pneumatic diaphragm valves for regulating the flow of condensed water and / or steam in the pipeline, and the plurality of pneumatic diaphragm valves are respectively installed on the connecting pipeline between the steam processing unit and the heat exchange unit, on the connecting pipeline between the steam processing unit and the secondary hot air heat exchanger (204), and on the connecting pipeline between the mixing unit and the secondary hot air heat exchanger (204).

5. The system according to claim 3 or 4, characterized in that The monitoring and feedback unit comprises a primary temperature sensor (601) and a secondary temperature sensor (602), wherein the primary temperature sensor (601) is electrically connected to the air outlet of the primary hot air heat exchanger (203) and is used to adjust the hot air temperature at the air outlet of the primary hot air heat exchanger (203); and the secondary temperature sensor (602) is electrically connected to the air outlet of the secondary hot air heat exchanger (204) and is used to feed back the heat source temperature at the air outlet of the secondary hot air heat exchanger (204).

6. The system according to claim 1, 2, 3 or 4, characterized in that The steam processing unit comprises a steam pipe network (101), a manual stop valve (102), a first filter (103), and a steam-water separator (104) which are sequentially connected along the steam flow direction.

7. The system according to claim 1, 2, 3 or 4, characterized in that The mixing unit includes a condensed water tank (301).

8. A method for recovering waste heat from condensed water of a silk thread, characterized in that: The following steps are involved: Recovering the high-temperature condensed water and the first low-temperature condensed water discharged from the steam processing unit, the air processing unit and the heat exchange unit to the mixing unit; The mixing unit transports the high-temperature condensed water to the first-stage hot air heat exchanger (203) of the air processing unit to preheat the air therein to obtain hot air and second-stage low-temperature condensed water; The hot air is transported to the secondary hot air heat exchanger (204) of the air handling unit for secondary heating to obtain a heat source; The first low-temperature condensed water and the second low-temperature condensed water are transported to a condensed water recovery unit.

9. The method according to claim 8, characterized in that The method further includes: monitoring the current temperature of the hot air in real time, and if the current temperature is not within the target temperature range, adjusting the flow rate of the high-temperature condensed water delivered by the mixing unit to the first-level hot air heat exchanger (203) to correct the current temperature.

10. The method according to claim 8 or 9, characterized in that The method further comprises: monitoring the real-time temperature of the heat source, and if the real-time temperature is not within a preset temperature range, adjusting the steam flow rate delivered by the steam processing unit to the secondary hot air heat exchanger (204) to correct the real-time temperature.

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