Device for utilizing step waste heat in degreasing section

Abstract

The utility model relates to a device for utilizing step waste heat in a degreasing section, and belongs to the technical field of cold-rolled strip coating. According to the system, a heat exchange water circulation system is arranged at the front end of a degreasing section process, and the system sequentially comprises a flue gas heat exchanger, a heat exchanger, a heat exchanger and a heat exchanger in the water circulation direction, the heat exchange water tank is adjacent to the degreasing section on-line tank, and the bottom of the heat exchange water tank is not communicated with the degreasing section on-line tank; the spraying device is used for spraying the heated heat exchange water to the surface of the running strip steel; the collecting device is used for collecting the cooling heat exchange water contacted with the strip steel; and the pump is used for conveying the collected heat exchange water to the flue gas heat exchanger. According to the scheme, gradient utilization of waste heat of the degreasing section can be achieved, energy efficiency is improved, energy consumption is reduced, and meanwhile production stability and product quality are guaranteed. Compared with the prior art, according to the scheme, waste heat resources can be more effectively utilized, the operation cost is reduced, and environmental protection and sustainable development are promoted.

Description

TECHNICAL FIELD

[0001] The utility model belongs to cold-rolled plate strip coating technology field relates to a device that degreasing section utilizes cascade waste heat. BACKGROUND

[0002] In the field of cold-rolled plate strip coating, the degreasing section is a key link in the production line, and its main function is to clean the grease and other contaminants on the surface of the strip steel. With the continuous improvement of environmental protection and energy saving requirements, how to efficiently utilize the waste heat resources of the degreasing section has become an important research topic.

[0003] Traditional degreasing section heating mainly uses steam pipeline to indirectly heat alkaline degreasing liquid and cleaning liquid. With the development of technology, attention has been paid to the utilization of annealing furnace flue gas waste heat. The flue gas of the annealing furnace is used to heat the degreasing liquid through a heat exchanger to reduce steam consumption. However, due to the large temperature fluctuation of the flue gas waste heat and the fast speed of the strip steel passing through, the specification is various, and the feedback time window is limited, so the comprehensive effect of waste heat utilization is not ideal. For example, some production lines directly pump the alkaline solution of the degreasing section into the heat exchanger to exchange heat with the annealing furnace flue gas in the heat exchanger. Due to the high content of contaminants such as grease and impurities in the alkaline solution during use, this method recovers part of the waste heat, but has problems such as easy boiling, pipe blockage and pipe explosion, resulting in frequent maintenance shutdown and accidents.

[0004] In recent years, in order to solve the above problems, some production lines have begun to try to use relatively clean water, such as soft water / desalinated water, as an intermediate heat exchange medium, and then return to the degreasing section circulating tank / process tank for indirect heating. Although this method solves the problem of frequent pipe blockage and pipe explosion, the temperature difference is too small, resulting in unreasonable heat transfer driving force, so the heat transfer and utilization effect is very limited. The use of superheated water system can improve the temperature difference gradient within a limited range, and a separate closed-loop pressure system needs to be added, which requires higher safety and maintenance requirements.

[0005] Therefore, the existing degreasing section waste heat recovery and utilization technology still has room for optimization and improvement in terms of conversion rate, stability, and safety and reliability. UTILITY MODEL CONTENTS

[0006] Therefore, the purpose of the utility model is to provide a degreasing section utilizing cascade waste heat method and device to improve waste heat utilization efficiency, reduce energy consumption, reduce production cost, and at the same time ensure the stability of production and product quality.

[0007] To achieve the above purpose, the utility model provides the following technical scheme:

[0008] A degreasing section utilizing cascade waste heat device is provided with a heat exchange water circulation system at the front end of the degreasing section process, which includes in sequence along the water circulation direction:

[0009] A flue gas heat exchanger is used to exchange heat between the heat exchange water and the flue gas to be discharged in the furnace area.

[0010] A heat exchange water tank is arranged adjacent to the online tank in the degreasing section and the bottoms are not communicated.

[0011] A spraying device is used to spray the heated heat exchange water to the surface of the running strip steel.

[0012] A collecting device is used to collect the cooled heat exchange water after contacting with the strip steel.

[0013] A pump is used to deliver the collected heat exchange water to the flue gas heat exchanger.

[0014] Optionally, a water supplement pipeline is arranged at the heat exchange water tank for supplementing soft water or desalted water during circulation start-up.

[0015] Optionally, a negative pressure collecting pipeline is arranged above the heat exchange water tank for collecting hot gas and alkali mist during the process.

[0016] Optionally, a partition groove plate with a baffle is arranged inside the heat exchange water tank to form a communication structure with the online tank in the degreasing section and the bottoms are not communicated.

[0017] Optionally, two oppositely arranged partition groove plates are arranged between the heat exchange water tank and the online tank in the degreasing section, one end of each of the two partition groove plates is provided with an angle-adjustable baffle, and a passage for the strip steel to pass through is formed between the two baffles.

[0018] Optionally, temperature monitoring instruments, flow meters, pressure switches, liquid level meters, and pH detection devices are arranged in the heat exchange water circulation system.

[0019] Optionally, the spraying device adopts a spray / waterfall type heat exchange to reduce the heat demand of the next process.

[0020] Optionally, a heat exchange water outlet is arranged below the heat exchange water circulation system.

[0021] Optionally, the heat exchange water circulation system is arranged in the heat exchange water spraying and circulating area; the heat exchange tank can be arranged in the area of the alkali spraying tank device group, or can be arranged separately and adjacent to the alkali spraying tank.

[0022] Optionally, the defatting section includes an alkali spraying section, an alkali brushing section, an electrolytic defatting section, a water brushing section, and a fresh water spraying section along the process route; the alkali spraying section and the alkali brushing section are connected to an alkali liquor circulation system; the electrolytic defatting section is connected to an alkaline electrolyte circulation system; the water brushing section and the fresh water spraying section are connected to a water circulation system; the alkali spraying section, the alkali brushing section, the electrolytic defatting section, the water brushing section, and the fresh water spraying section are connected to an alkali mist collection and purification system; the alkali liquor circulation system, the alkaline electrolyte circulation system, and the water circulation system are each connected to a steam heating system, and steam condensate water is recovered and supplemented to the last stage of the fresh water spraying section.

[0023] The beneficial effects of the present utility model are as follows:

[0024] Improving the utilization efficiency of waste heat: through the method of cascade waste heat utilization, the present scheme can more effectively utilize the waste heat generated in the defatting section, thereby improving the overall energy utilization efficiency.

[0025] Reducing energy consumption: optimizing the waste heat utilization of the defatting section, reducing the dependence on traditional steam heating, thereby reducing energy consumption and achieving the goal of energy saving and emission reduction.

[0026] Stabilizing the production process: through the intelligent control system, real-time monitoring and adjustment of process parameters are realized to cope with the challenges of smoke temperature fluctuations and high strip steel passing speed, thereby stabilizing the production process and reducing production interruptions and accidents.

[0027] Improving product quality: optimizing the heat exchange process ensures the cleaning effect of the defatting section, thereby improving the quality of the final product.

[0028] Reducing operating costs: reducing energy consumption and improving production efficiency, reducing the operating costs of the defatting section, and improving the economic benefits of enterprises.

[0029] Environmental protection and sustainable development: meeting the current environmental protection and energy saving and carbon reduction requirements, contributing to the sustainable development of the steel industry.

[0030] Reducing equipment maintenance and failures: by using cleaner water as the intermediate heat exchange medium, the risk of pipe blockage and pipe explosion caused by alkali liquor as the heat exchange liquid is reduced, and the maintenance requirements and failure rate of the equipment are reduced. Compared with the superheated water system which also uses clean water, the closed circuit requirement is also reduced, and the temperature and pressure range of the system operation is safer and more easily obtained.

[0031] Improving heat exchange efficiency: adopting direct contact heat exchange method, the strip steel and water are both good heat conductive materials, which can complete heat exchange in a short time, improve heat exchange efficiency, and reduce heat loss.

[0032] Enhancing system adaptability: the present scheme is applicable to new lines and transformed lines, improving the adaptability and flexibility of the scheme application system.

[0033] The other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description, and it is in terms of this description that there is to be understood the objects and advantages of the present application. The objects and other advantages of the present application can be realized and attained by means of the instrumentalities and combinations particularly pointed out in the following description. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the drawings, in which:

[0035] Fig. 1 is a schematic diagram of the present application;

[0036] Fig. 2 is a schematic diagram of part of the details of the present application.

[0037] The drawings show: 1 flue gas heat exchanger, 2 pump, 3 filter device, 4 instrument, 5 partition groove plate, 6 water supply pipeline, 7 alkali spraying section, 8 alkali liquor circulation system, 9 alkali scrubbing section, 10 electrolytic degreasing section, 11 alkaline electrolyte circulation system, 12 water scrubbing section, 13 water circulation system, 14 fresh water spraying section, 15 alkali mist collection and purification system, 16 steam heating system, 17 heat exchange water spraying and circulation area, 18 wringing device, 19 heat exchange water outlet, 20 spraying device, 21 negative pressure collection pipeline, 22 baffle, 23 alkali spraying groove device group. DETAILED DESCRIPTION

[0038] The embodiments of the present application will be described below through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present specification. The present application can also be implemented or applied through other different concrete embodiments, and each detail in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner, and the features in the following embodiments and examples can be combined with each other without conflict.

[0039] The drawings are only used for illustrative description, and the representation is only a schematic diagram, not a physical drawing, and should not be understood as a limitation of the present application; in order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0040] The same or similar reference signs in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that, if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back" and the like are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and thus the terms describing the positional relationships in the drawings do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation and be operated, and thus the terms describing the positional relationships in the drawings are only used for exemplary illustration and cannot be understood as a limitation on the present application, and for those skilled in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0041] Please refer to Figs. 1-2 The various components of the present scheme are carefully designed and integrated to form an efficient and stable residual heat utilization system for the degreasing section. The following is a detailed description of the connection relationship and function of each component:

[0042] The flue gas heat exchanger 1 is located at the flue gas discharge port of the annealing furnace, and its function is to capture the heat in the flue gas and transfer the heat to the circulating water through heat exchange. The flue gas heat exchanger 1 is connected to the pump 2 to ensure that the circulating water can flow smoothly through the heat exchanger 1 and absorb heat. The pump 2 is responsible for transporting the heated circulating water from the flue gas heat exchanger to the spraying device 20. The design of the pump 2 should take into account the flow and pressure requirements to meet the heat exchange requirements under different working conditions. The filter device 3 is installed in the circulating water circuit to remove suspended solids and impurities in the water, prevent the heat exchanger and water pump from being blocked, and ensure long-term stable operation of the system. The instrument 4 includes a thermometer, a flowmeter and a pressure switch, etc., which are installed at key positions to monitor the temperature, flow and pressure of the circulating water in real time, and provide data support for the intelligent control system. The groove plate 5 is arranged between the heat exchange tank and the alkali tank, which plays a role in isolating the two liquids and guiding the running of the strip. The design of the groove plate should take into account the need to prevent water from splashing out and ensure smooth passage of hot gas. The water supply pipeline 6 is connected to the heat exchange tank to supplement the water loss of the circulating water during operation and maintain the stability of the circulating water level.

[0043] The alkali spraying tank device group 23 is located in the alkali spraying section 7. The alkali spraying section 7, the alkali liquid circulation system 8, the alkali brushing section 9, the electrolytic degreasing section 10, the alkaline electrolyte circulation system 11, the water brushing section 12, the water circulation system 13, and the new water spraying section 14 constitute different stage groups of the degreasing section, each of which has a specific cleaning and rinsing function. These parts are connected to each other through pipes and valves to form a complete circulation system.

[0044] The alkali mist collection and purification system 15 is connected with the upper space of each tank of the degreasing section, used for collecting and purifying the alkali mist generated in the degreasing process, and protecting the environment. The steam heating system 16 is used for supplementing the heat source and heating various process liquids. The condensed water is collected and reused by being supplemented to the fresh water spraying section 14. The heat exchange water spraying and circulating area 17 is used for installing the heat exchange water circulating system A, which directly contacts with the strip to exchange heat. The squeezing device 18 is used for squeezing the liquid on the surface of the strip, and is arranged at the front and rear ends of the tank body, so as to prepare for entering the process section and the subsequent process.

[0045] The heat exchange water outlet 19 is connected with the heat exchange water tank, used for discharging the used heat exchange water from the system, and filtering or treating. The spraying device 20 is used for spraying the heat exchange water to the surface of the strip to realize direct contact heat exchange. The design of the spraying device should consider the requirements of spraying uniformity and heat exchange efficiency. The negative pressure collection pipeline 21 is connected with the alkali mist collection and purification system 15, used for collecting the hot gas and alkali mist above the tank body, and guiding to the purification system. The baffle 22 is arranged at the end of the partition tank plate 5, used for guiding the strip to run and preventing water from splashing out. The design of the baffle 22 should consider the requirements of preventing water from splashing out and ensuring the smooth passing of the strip.

[0046] The heat exchange water exchanges heat with the flue gas to be discharged in the furnace area through the flue gas heat exchanger 1, so that the water temperature is raised to 80-85 degrees. The heat exchanged hot water returns to the inlet of the heat exchange tank by using high difference, and the temperature monitoring instrument 4 is arranged at the inlet, so as to monitor the water temperature in real time. The heat exchange water enters the spraying device 20 or the flow guide groove through the inlet, and is directly sprayed to the surface of the running strip. Since the water and the strip both have good thermal conductivity, the heat exchange process fully optimizes the temperature difference gradient, improves the heat transfer efficiency, and reduces the heat demand of the subsequent process.

[0047] The heat exchange water temperature decreases after contacting with the strip, and is collected in the lower section area of the heat exchange tank. The heat exchange water outlet 19 is arranged at the bottom of the tank, connected to the filtering device 3 outside the tank. The temperature transmitter instrument 4 and the flow instrument 4 are arranged in the pipeline section from the outlet to the filtering device 3, and a pressure switch can be optionally matched, so as to prevent the phenomenon of suction. A discharge branch pipe is arranged in front of the inlet of the filtering device 3 in the pipeline section, which is connected to the alkali liquor circulating system 8 nearby, and the discharge into the alkali liquor circulating system 8 is controlled by a valve. The tank body can also be provided with a liquid level instrument, used for monitoring the liquid level, and ensuring the stable operation of the system. The above instruments are used for monitoring the process parameters, and participating in the intelligent control of production, so as to optimize the production process.

[0048] The heat exchange water after cooling is transported to the aforementioned flue gas heat exchanger 1 by the pump 2, exchanges heat with the flue gas, and returns to the inlet of the heat exchange tank after being heated, so as to complete the circulation process. The heat exchange water tank is provided with a water supplement pipeline 6 above the side, used for supplementing soft water or desalted water during circulation start. The heat exchange water tank is communicated with the adjacent degreasing section tank above, the hot gas in the process is collected together with the alkali mist in the degreasing section by the negative pressure collection pipeline 21, and enters the alkali mist collection and purification system 15, and the related purification process is carried out by the subsequent purification tower.

[0049] The middle part of the slot plate 5 is provided with a long window for the passage of the strip steel, and the upper and lower sides are provided with adjustable baffles 22. The plate end near the position of the strip steel is provided with a flexible rubber eave to help reduce the heat exchange water carried by the strip steel into the other side of the slot plate 5, i.e. the degreasing section line groove, and to avoid scratching the strip steel. The inner slot separated by the slot plate 5 is an inner part, or can be made into two different groove bodies, mainly considering the adaptability of this method to the existing line modification project. The liquid in the inner slot is relatively clean heat exchange water, which is not connected to the bottom of the degreasing liquid, and the top space is connected to the degreasing liquid groove for exhaust.

[0050] The degreasing section is divided into an alkali spraying section 7, an alkali brushing section 9, an electrolytic degreasing section 10, a water brushing section 12, and a new water spraying section 14 according to the running direction of the strip steel. Through the above design and the sequential cooperation of the process flow, the present scheme can realize efficient utilization of the waste heat of the degreasing section, improve energy efficiency, reduce energy consumption, and at the same time ensure the stability of production and product quality.

[0051] The present scheme adopts an innovative design in the first-stage alkali spraying section, which fully utilizes the temperature gradient of the subsequent annealing furnace flue gas heat exchange water, especially at the strip steel inlet position, where the strip steel temperature is the lowest, especially in winter. Through the spraying type or waterfall type spraying mode, the circulating liquid directly exchanges heat with the steel belt, utilizes a more optimal heat transfer temperature difference gradient, and partially replaces the heat required to be supplemented in the original alkali liquid tank, thereby reducing the heat demand of the subsequent stage. The inner slot and the heat exchange water circulation system A are designed to be open, and the heat exchange water directly exchanges heat with the strip steel, which significantly improves the waste heat utilization efficiency compared with the non-contact indirect heat exchange through the pipe in the tank.

[0052] The preferred heat exchange water circulation amount is about 20-30 cubic meters / hour. Due to the limited volume of the separation tank itself, the heat exchange water circulation needs to be supported by the water supply system when it starts, so the water supply diameter needs to be appropriately enlarged. For example, the temperature difference between the heat exchange water and the inlet steel belt is 50 degrees, plus the efficiency improvement of direct heat exchange compared with indirect heat exchange, which can replace about 0.8-1 tons of steam usage under ideal conditions.

[0053] Compared with the existing line scheme, the supplementary heat source to the water spraying section, the reference temperature of the water spraying section process circulating water is above 50 degrees, and the temperature difference with the heat exchange water is usually not more than 35 degrees. Therefore, the temperature gradient matching of the present scheme is significantly increased, and the direct contact heat exchange effect is better than the indirect contact. The comprehensive energy saving level of the whole degreasing section waste heat cascade utilization is expected to be 15-18%, of which more than 5% is used for strip steel heating, and the rest is used for liquid system heating to process temperature and heat loss supplement.

[0054] By monitoring the changes of these data in the production process, and using the first time "window" of the strip steel contacting with the position and heat exchange, the scheme helps to judge whether the subsequent steam usage needs to be adjusted in time. Generally, the feedback time period required for steam heating tank liquid is long, and the method can make the pre-judgment and intervention time of the temperature control system of the degreasing section advance. The influencing factors of the changes include the changes of the strip specifications batch, the environment temperature or the flue gas temperature, and the effective heat obtained by the heat exchange water absorbed to obtain the temperature rise.

[0055] By responding and intervening the steam usage of the next stage early, and combining with the production line automatic control system, the scheme provides deep and fine support for further energy saving and carbon reduction.

[0056] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A device for utilizing waste heat in a degreasing stage, characterized in that, A hot water circulation system is installed at the front end of the degreasing section, comprising the following components along the water circulation direction: Flue gas heat exchangers are used to exchange heat between hot water and flue gas to be discharged from the furnace area. A hot water exchange tank is provided, which is adjacent to the degreasing section's upper channel but not interconnected at the bottom. The spraying device is used to spray the heated hot water onto the surface of the strip steel in operation; A collection device is used to collect the cooled hot water that comes into contact with the steel strip. Pumps are used to transport the collected hot water to the flue gas heat exchanger.

2. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, A water supply pipe is installed at the hot water tank to replenish soft water or desalinated water during circulation startup.

3. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, A negative pressure collection pipeline is installed above the hot water tank to collect the hot air and alkaline mist from the degreasing section during the process.

4. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, The interior of the hot water tank is equipped with a baffle plate, which forms a non-interconnected connection with the degreasing section's upper channel.

5. The device for utilizing waste heat in the degreasing section according to claim 4, characterized in that, Two opposing partition plates are installed between the hot water exchange tank and the degreasing section trough. Each of the two partition plates has an adjustable baffle at one end, and a channel for the strip steel to pass through is formed between the two baffles.

6. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, The hot water circulation system is equipped with temperature monitoring instruments, flow meters, pressure switches, level gauges, and pH detection devices.

7. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, The spray device adopts a spray / waterfall flow heat exchange to reduce the heat demand of the subsequent process.

8. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, A hot water outlet is installed below the hot water circulation system.

9. The device for utilizing waste heat in the degreasing section according to claim 1, characterized in that, The hot water exchange circulation system is located within the hot water exchange spray and circulation area; it is located before the alkaline spraying process in the degreasing section.

10. The apparatus for utilizing waste heat in the degreasing section according to any one of claims 1 to 9, characterized in that, The degreasing section, along the process route, includes an alkaline spray section, an alkaline scrubbing section, an electrolytic degreasing section, a water scrubbing section, and a fresh water spray section. Both the alkaline spray section and the alkaline scrubbing section are connected to the alkaline solution circulation system. The electrolytic degreasing section is connected to the alkaline electrolyte circulation system. The water scrubbing section and the fresh water spray section are connected to the water circulation system. All three sections—alkaline spray section, alkaline scrubbing section, electrolytic degreasing section, water scrubbing section, and fresh water spray section—are connected to the alkaline mist collection and purification system. The alkaline solution circulation system, the alkaline electrolyte circulation system, and the water circulation system all have steam heating systems, and the collected steam condensate is returned to the fresh water spray section.

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