In-situ rapid descaling system and method for tail gas heat exchanger

Abstract

The invention relates to an in-situ rapid descaling system for a tail gas heat exchanger. The in-situ rapid descaling system is characterized by comprising the tail gas heat exchanger, a descaling liquid adding system, a liquid level indicating system and a temperature control heating system; the descaling liquid adding system is used for adding descaling liquid into the tail gas heat exchanger; the liquid level indicating system is used for monitoring the liquid level height of descaling liquid in the tail gas heat exchanger; and the temperature control heating system is used for heating the descaling liquid in the tail gas heat exchanger. When the liquid level of the descaling liquid in the tail gas heat exchanger exceeds the height of the metal conductive rod with the corresponding height, the bottommost metal conductive rod, the direct-current power supply, the corresponding liquid level indicator lamp and the metal conductive rod with the corresponding height form a loop, the liquid level indicator lamp is turned on, and therefore the height of the descaling liquid in the tail gas heat exchanger can be accurately indicated. When the height of the descaling liquid level meets the requirement, the temperature control heating device is started to heat the jacket, so that the temperature of the descaling liquid is increased, and the descaling liquid can quickly dissolve dirt.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchangers, and in particular relates to an in-situ rapid descaling system and method for an exhaust gas heat exchanger. Background Art

[0002] Under the background of "dual carbon", the importance of industrial tail gas waste heat utilization and energy-saving technology development is more prominent. Typical industrial tail gas is characterized by low temperature, and many tail gases contain a large amount of dust particles, which makes the utilization of tail gas waste heat difficult and costly. Among them, sludge drying tail gas is the most typical example. Sludge is a solid organic waste discharged during sewage treatment, with characteristics such as high moisture, high organic matter, odor and viscosity. According to statistics, the current annual discharge of wet sludge (water content 80%) in the country exceeds 60 million tons, and continues to increase year by year. Thermal drying is an important way to achieve sludge reduction and stabilization, and ultimately realize the energy and resource utilization of sludge. Thermal drying has many advantages such as large processing capacity, fast drying speed, high integration and small footprint. It has been widely promoted and applied in the sludge treatment industry at home and abroad, and is currently the mainstream sludge drying technology. The main disadvantage of thermal drying is its high energy consumption, which is determined by the principle of thermal drying: during the thermal drying process, the sludge is heated to the boiling point of water and the water vaporizes. In this process, the sludge absorbs a large amount of heat, resulting in high energy consumption for drying.

[0003] Sludge drying tail gas contains a large amount of latent heat of evaporation, and the temperature is mainly between 90 and 100 ° C. The waste heat utilization potential is large. Typical indirect heat exchangers such as spiral plate heat exchangers or shell and tube heat exchangers can be used to extract the waste heat of sludge drying tail gas to realize waste heat utilization. However, sludge drying tail gas contains a large number of complex components such as sludge dust particles and volatiles. Under the joint action of a large amount of water vapor contained in the tail gas, the sludge dust particles become moist and have strong adhesion, making the heat exchanger very easy to scale and clog, and unable to maintain long-term stable operation. Although intermittent spraying can achieve a certain degree of cleaning of mud and dirt, after a long period of operation, stubborn dirt will still form on the surface of the heat exchanger, which cannot be removed by conventional spraying, and the heat exchanger needs to be disassembled and cleaned. However, the industrial-grade tail gas heat exchanger has a large structure, a large workload for disassembly and cleaning, and a long cycle, which affects the continuous and stable operation of the waste heat recovery system. This is one of the main reasons why waste heat from sludge drying tail gas is rarely utilized in actual projects.

[0004] Based on the scaling and descaling problems faced by exhaust gas heat exchangers during operation, the patent of this invention proposes a new method for rapid in-situ descaling of exhaust gas heat exchangers without disassembly and cleaning. Summary of the invention

[0005] The main purpose of the present invention is to propose an in-situ rapid descaling system and method for an exhaust gas heat exchanger, which can effectively solve the problems in the background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] An in-situ rapid descaling system for an exhaust gas heat exchanger, comprising:

[0008] Exhaust gas heat exchanger;

[0009] A descaling liquid adding system, used for adding descaling liquid to the exhaust gas heat exchanger;

[0010] Liquid level indication system, used to monitor the liquid level of descaling liquid in the exhaust gas heat exchanger;

[0011] Temperature controlled heating system, used to heat the descaling liquid in the exhaust gas heat exchanger.

[0012] Preferably, the descaling liquid adding system comprises

[0013] A proportional pump connected to the exhaust gas heat exchanger through a pipeline;

[0014] A descaling liquid tank connected to the proportional pump via a pipeline;

[0015] A water pump is connected to the proportional pump through a pipeline.

[0016] Preferably, the liquid level indication system comprises

[0017] A plurality of metal conductive rods are arranged at different heights through the exhaust gas heat exchanger;

[0018] A direct current power supply is connected to the plurality of metal conductive rods through circuits, and except for the circuit connected to the metal conductive rod at the bottom, indicator lights are arranged in the remaining circuits.

[0019] Preferably, the temperature control heating system comprises

[0020] A jacket, disposed outside the tail gas heat exchanger;

[0021] At least one thermometer, disposed in the exhaust gas heat exchanger;

[0022] The temperature control and heating device is electrically connected to the jacket and the thermometer through wires.

[0023] Preferably, an insulating tape is provided between the metal conductive rod and the exhaust gas heat exchanger.

[0024] Preferably, an annular spray device is provided at the top of the exhaust gas heat exchanger.

[0025] Preferably, the annular spray device has an annular channel and a spray water inlet connected to the annular channel, and a plurality of swirl atomizing nozzles are arranged at the bottom of the annular channel.

[0026] A method for rapid in-situ descaling of an exhaust gas heat exchanger, using the above-mentioned rapid in-situ descaling system for an exhaust gas heat exchanger, comprises the following steps:

[0027] S1: adding descaling liquid to the exhaust gas heat exchanger through the descaling liquid adding system;

[0028] The descaling liquid uses an alkaline liquid with a concentration of 0.5% to 5% NaOH. The descaling liquid in the descaling liquid tank and the feed water of the water pump are mixed in a certain proportion by a proportional pump and then sent to the exhaust gas heat exchanger.

[0029] S2: Monitor the liquid level of the descaling liquid in the exhaust gas heat exchanger through the liquid level indication system;

[0030] When the descaling liquid level in the exhaust gas heat exchanger exceeds the height of the metal conductive rod of the corresponding height, the bottom metal conductive rod, the DC power supply, the corresponding liquid level indicator light, and the metal conductive rod of the corresponding height form a loop to light up the liquid level indicator light.

[0031] S3: The descaling liquid in the exhaust gas heat exchanger is heated by the temperature control heating system, so that the descaling liquid can quickly dissolve the dirt;

[0032] When the descaling liquid level meets the requirements, turn on the temperature control heating device to heat the jacket, thereby increasing the temperature of the descaling liquid, which can achieve rapid dissolution of scale by the descaling liquid, and use a thermometer to monitor the descaling liquid temperature in real time. The heating temperature of the descaling liquid is 60-85°C. When the descaling liquid rises to the set temperature, the temperature of the descaling liquid is maintained for 1-4 hours through the temperature control heating system;

[0033] S4: release descaling liquid;

[0034] When the dirt is completely dissolved, open the exhaust gas heat exchanger outlet valve to release the descaling liquid, and turn on the annular spray device to clean the inside of the exhaust gas heat exchanger.

[0035] The present invention provides an in-situ rapid descaling system and method for an exhaust gas heat exchanger, which has the following beneficial effects:

[0036] 1. When the descaling liquid level in the exhaust gas heat exchanger exceeds the height of the metal conductive rod of the corresponding height, the bottom metal conductive rod, the DC power supply, the corresponding liquid level indicator light, and the metal conductive rod of the corresponding height form a loop, so that the liquid level indicator light is on, thereby accurately indicating the descaling liquid level in the exhaust gas heat exchanger.

[0037] 2. When the descaling liquid level meets the requirements, turn on the temperature control heating device to heat the jacket, thereby increasing the temperature of the descaling liquid, which can achieve rapid dissolution of scale by the descaling liquid.

[0038] 3. The exhaust gas heat exchanger in-situ rapid descaling system and method of the present invention does not require disassembly and cleaning of the exhaust gas heat exchanger. The operation is simple and convenient, and the cleaning can be performed quickly to ensure the continuous and stable operation of the waste heat recovery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the in-situ rapid descaling system for the exhaust gas heat exchanger of the present invention;

[0040] Figure 2 It is a schematic structural diagram of the annular spray device of the present invention.

[0041] In the figure: 1. exhaust gas heat exchanger; 2. metal conductive rod; 3. insulating tape; 4. outlet valve; 5. descaling liquid tank; 6. water pump; 7. proportional pump; 8. DC power supply; 9. indicator light; 10. jacket; 11. temperature control heating device; 12. thermometer; 13. annular spray device; 14. exhaust gas inlet; 15. return water inlet; 16. water supply outlet; 17. exhaust gas outlet; 18. wire; 19. line; 20. spray water inlet; 21. annular channel; 22. swirl atomizing nozzle; 23. pipeline. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0043] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Example

[0047] Reference Figure 1-2 , an in-situ rapid descaling system for an exhaust gas heat exchanger, comprising

[0048] The tail gas heat exchanger 1 is a shell and tube heat exchanger or a spiral plate heat exchanger;

[0049] A descaling liquid adding system, used for adding descaling liquid to the exhaust gas heat exchanger 1;

[0050] A liquid level indicating system, used to monitor the liquid level of the descaling liquid in the exhaust gas heat exchanger 1;

[0051] The temperature control heating system is used to heat the descaling liquid in the exhaust gas heat exchanger 1.

[0052] In a specific embodiment, the descaling liquid addition system comprises

[0053] A proportional pump 7 connected to the exhaust gas heat exchanger 1 through a pipeline 23;

[0054] The descaling liquid tank 5 is connected to the proportional pump 7 through a pipeline 23;

[0055] The water pump 6 is connected to the proportional pump 7 through a pipeline 23 .

[0056] The descaling liquid in the descaling liquid tank 5 and the feed water of the water pump 6 are mixed in a certain proportion by the proportional pump 7 and then sent to the exhaust gas heat exchanger 1 .

[0057] In-situ descaling requires that the liquid level height can be determined after the descaling liquid is sent into the exhaust gas heat exchanger 1. Since the inside of the exhaust gas heat exchanger 1 is clogged with a large amount of dirt, the conventional liquid level gauge cannot work normally and the glass sight glass cannot observe the internal liquid level. It is necessary to develop a new descaling liquid level indication method.

[0058] In a specific embodiment, the liquid level indication system comprises

[0059] A plurality of metal conductive rods 2 are arranged at different heights through the exhaust gas heat exchanger 1;

[0060] The DC power supply 8 is connected to the plurality of metal conductive rods 2 through lines 19 , respectively. Except for the line 19 connected to the metal conductive rod 2 at the bottom, the remaining lines 19 are all provided with liquid level indicator lights 9 .

[0061] When the descaling liquid level in the exhaust gas heat exchanger 1 exceeds the height of the metal conductive rod 2 of the corresponding height, the bottom metal conductive rod 2, the DC power supply 8, the corresponding liquid level indicator light 9, and the metal conductive rod 2 of the corresponding height form a loop, making the liquid level indicator light 9 light up.

[0062] Specifically, in this embodiment, the number of metal conductive rods 2 is four, namely 0#, 1#, 2# and 3# from low to high, and the number of liquid level indicator lights 9 is three, namely 1#, 2# and 3#. As the descaling liquid level gradually increases and exceeds the height of the 1#, 2# and 3# metal conductive rods 2, the 1#, 2# and 3# liquid level indicator lights 9 gradually become brighter, thereby accurately indicating the descaling liquid level in the exhaust gas heat exchanger 1.

[0063] In a specific embodiment, the temperature control heating system comprises

[0064] A jacket 10, disposed outside the exhaust gas heat exchanger 1;

[0065] At least one thermometer 12, disposed in the exhaust gas heat exchanger 1;

[0066] The temperature control and heating device 11 is electrically connected to the jacket 10 and the thermometer 12 through a wire 18 .

[0067] When the descaling liquid level meets the requirement, the temperature control heating device 11 is turned on to heat the jacket 10, thereby increasing the temperature of the descaling liquid, so that the descaling liquid can quickly dissolve the scale, and the thermometer 12 is used to monitor the descaling liquid temperature in real time.

[0068] In a specific embodiment, an insulating tape 3 is provided between the metal conductive rod 2 and the exhaust gas heat exchanger 1 .

[0069] In a specific embodiment, an annular spray device 13 is disposed at the top of the exhaust gas heat exchanger 1 .

[0070] When the dirt is completely dissolved, the outlet valve of the exhaust gas heat exchanger 1 is opened to release the descaling liquid, and the annular spray device 13 is turned on to clean the inside of the exhaust gas heat exchanger 1.

[0071] In a specific embodiment, the annular spray device 13 has an annular channel 21 and a spray water inlet 20 connected to the annular channel 21. A plurality of swirl atomizing nozzles 22 are arranged at the bottom of the annular channel 21, and the cleaning efficiency is high.

[0072] The present invention also provides an in-situ rapid descaling method for an exhaust gas heat exchanger, comprising the following steps:

[0073] S1: adding descaling liquid to the exhaust gas heat exchanger 1 through the descaling liquid adding system;

[0074] The descaling liquid is an alkaline liquid with a concentration of 0.5% to 5% NaOH. The descaling liquid in the descaling liquid tank 5 and the feed water of the water pump 6 are mixed in a certain proportion by the proportional pump 7 and then sent to the exhaust gas heat exchanger 1.

[0075] S2: monitoring the liquid level of the descaling liquid in the exhaust gas heat exchanger 1 through the liquid level indication system;

[0076] When the descaling liquid level in the exhaust gas heat exchanger 1 exceeds the height of the metal conductive rod 2 of the corresponding height, the bottom metal conductive rod 2, the DC power supply 8, the corresponding liquid level indicator light 9, and the metal conductive rod 2 of the corresponding height form a loop, making the liquid level indicator light 9 light up.

[0077] S3: heating the descaling liquid in the exhaust gas heat exchanger 1 by the temperature control heating system, so that the descaling liquid can quickly dissolve the dirt;

[0078] When the descaling liquid level meets the requirements, the temperature control heating device 11 is turned on to heat the jacket 10, thereby increasing the temperature of the descaling liquid, so that the descaling liquid can quickly dissolve the scale, and the thermometer 12 is used to monitor the descaling liquid temperature in real time. The heating temperature of the descaling liquid is 60-85°C. When the descaling liquid rises to the set temperature, the temperature of the descaling liquid is maintained for 1-4 hours by the temperature control heating system;

[0079] S4: release descaling liquid;

[0080] When the dirt is completely dissolved, the outlet valve 4 of the exhaust gas heat exchanger 1 is opened to release the descaling liquid, and the annular spray device 13 is turned on to clean the inside of the exhaust gas heat exchanger 1 .

[0081] After cleaning, the tail gas heat exchanger 1 can enter normal operation. According to the actual sludge thermal drying project, in order to recover the waste heat of the sludge drying tail gas, the tail gas is sent into the tail gas heat exchanger 1 through the tail gas inlet 14, and indirectly heat exchanged with the return water from the return water inlet 15, and the return water is heated to become high-temperature supply water and sent out from the water supply outlet 16. After heat exchange, the tail gas is discharged from the tail gas outlet 17, and the tail gas outlet 17 is controlled by the outlet valve 4.

[0082] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-situ rapid descaling system for an exhaust gas heat exchanger, characterized in that: include Exhaust gas heat exchanger; A descaling liquid adding system, used for adding descaling liquid to the exhaust gas heat exchanger; Liquid level indication system, used to monitor the liquid level of descaling liquid in the exhaust gas heat exchanger; Temperature controlled heating system, used to heat the descaling liquid in the exhaust gas heat exchanger.

2. The exhaust gas heat exchanger in-situ rapid descaling system according to claim 1, characterized in that: The descaling liquid adding system comprises A proportional pump connected to the exhaust gas heat exchanger through a pipeline; A descaling liquid tank connected to the proportional pump via a pipeline; A water pump is connected to the proportional pump through a pipeline.

3. The in-situ rapid descaling system for an exhaust gas heat exchanger according to claim 1, characterized in that: The liquid level indication system comprises A plurality of metal conductive rods are arranged at different heights through the exhaust gas heat exchanger; A direct current power supply is connected to the plurality of metal conductive rods through circuits, and except for the circuit connected to the metal conductive rod at the bottom, indicator lights are arranged in the remaining circuits.

4. The in-situ rapid descaling system for an exhaust gas heat exchanger according to claim 1, characterized in that: The temperature control heating system comprises A jacket, disposed outside the tail gas heat exchanger; At least one thermometer, disposed in the exhaust gas heat exchanger; The temperature control and heating device is electrically connected to the jacket and the thermometer through wires.

5. The in-situ rapid descaling system for an exhaust gas heat exchanger according to claim 4, characterized in that: An insulating tape is arranged between the metal conductive rod and the exhaust gas heat exchanger.

6. The in-situ rapid descaling system for an exhaust gas heat exchanger according to claim 1, characterized in that: An annular spray device is arranged on the top of the tail gas heat exchanger.

7. The in-situ rapid descaling system for an exhaust gas heat exchanger according to claim 6, characterized in that: The annular spray device comprises an annular channel and a spray water inlet connected to the annular channel, and a plurality of swirl atomizing nozzles are arranged at the bottom of the annular channel.

8. A method for rapid in-situ descaling of an exhaust gas heat exchanger, using the in-situ rapid descaling system for an exhaust gas heat exchanger according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: adding descaling liquid to the exhaust gas heat exchanger through the descaling liquid adding system; The descaling liquid uses an alkaline liquid with a concentration of 0.5% to 5% NaOH. The descaling liquid in the descaling liquid tank and the feed water of the water pump are mixed in a certain proportion by a proportional pump and then sent to the exhaust gas heat exchanger. S2: Monitor the liquid level of the descaling liquid in the exhaust gas heat exchanger through the liquid level indication system; When the descaling liquid level in the exhaust gas heat exchanger exceeds the height of the metal conductive rod of the corresponding height, the bottom metal conductive rod, the DC power supply, the corresponding liquid level indicator light, and the metal conductive rod of the corresponding height form a loop to light up the liquid level indicator light. S3: The descaling liquid in the exhaust gas heat exchanger is heated by the temperature control heating system, so that the descaling liquid can quickly dissolve the scale; when the descaling liquid level meets the requirements, the temperature control heating device is turned on to heat the jacket, thereby increasing the temperature of the descaling liquid, so that the descaling liquid can quickly dissolve the scale, and a thermometer is used to monitor the temperature of the descaling liquid in real time. The heating temperature of the descaling liquid is 60-85°C. When the descaling liquid rises to the set temperature, the temperature of the descaling liquid is maintained for 1-4 hours by the temperature control heating system; S4: release descaling liquid; When the dirt is completely dissolved, open the exhaust gas heat exchanger outlet valve to release the descaling liquid, and turn on the annular spray device to clean the inside of the exhaust gas heat exchanger.

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