CN104122193B - A synchronous online monitoring device for low-temperature corrosion process and state of flue gas cooler - Google Patents
A synchronous online monitoring device for low-temperature corrosion process and state of flue gas cooler Download PDFInfo
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Abstract
本发明公开了一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置，包括至少一个恒壁温换热管，恒壁温换热管从上至下依次由冷凝段、绝热段及蒸发段组成，监测时，恒壁温换热管的蒸发段置于尾部烟道内，且蒸发段的外壁通过导线连接有热电偶，恒壁温换热管的冷凝段外连接有强制对流散热的套管，强制对流散热的套管底部为开口，顶部开孔并与鼓风机通过空气管路连接，每个强制对流散热的套管支路上的空气管路上均设有调节阀以调控空气流量；恒壁温换热管内有用于换热的介质；本发明装置结构简单，无复杂连接，实施方便，可实现离线检测，金属壁温稳定，可真实反映同级换热器的低温腐蚀过程及状态。
The invention discloses a synchronous online monitoring device for the low-temperature corrosion process and state of a flue gas cooler, which comprises at least one constant wall temperature heat exchange tube. The constant wall temperature heat exchange tube consists of a condensation section, an adiabatic section and an evaporation When monitoring, the evaporation section of the constant wall temperature heat exchange tube is placed in the tail flue, and the outer wall of the evaporation section is connected with a thermocouple through a wire, and the outside of the condensation section of the constant wall temperature heat exchange tube is connected with a sleeve for forced convection heat dissipation. The bottom of the casing for forced convection heat dissipation is open, and the top is open and connected to the blower through an air pipeline. A regulating valve is installed on the air pipeline on each branch of the casing for forced convection heat dissipation to regulate the air flow; constant wall There is a medium for heat exchange in the warm heat exchange tube; the device of the present invention has a simple structure, no complicated connection, easy implementation, offline detection, stable metal wall temperature, and can truly reflect the low-temperature corrosion process and state of the heat exchanger at the same level.
Description
技术领域technical field
本发明属于烟气冷却器低温腐蚀过程及状态的监测技术领域，涉及一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置。The invention belongs to the technical field of monitoring the low-temperature corrosion process and state of a flue gas cooler, and relates to a synchronous on-line monitoring device for the low-temperature corrosion process and state of a flue gas cooler.
背景技术Background technique
对于火力发电厂来说，排烟热损失是锅炉各项热损失中最大的一项，一般在5％～8％，占锅炉总热损失的80％甚至更高。影响排烟热损失的主要因素是锅炉排烟温度，我国许多电站锅炉的排烟温度实际运行值达到130℃～150℃，高于设计值约20℃～50℃；大幅度降低排烟温度将极大地提高电站锅炉的经济性。经过实际计算发现：排烟温度能降低35℃左右，系统发电循环效率提高0.5％以上，每度电节约1.5克以上标准煤，具有明显的节能减排潜力。For thermal power plants, the exhaust heat loss is the largest among all the heat losses of the boiler, generally 5% to 8%, accounting for 80% or even higher of the total heat loss of the boiler. The main factor affecting the heat loss of the exhaust gas is the exhaust gas temperature of the boiler. The actual operating value of the exhaust gas temperature of many power plant boilers in my country reaches 130 ° C ~ 150 ° C, which is about 20 ° C ~ 50 ° C higher than the design value; a large reduction in the exhaust gas temperature will Greatly improve the economy of power plant boilers. After actual calculation, it is found that the exhaust gas temperature can be reduced by about 35°C, the power generation cycle efficiency of the system can be increased by more than 0.5%, and more than 1.5 grams of standard coal can be saved per kilowatt-hour of electricity, which has obvious potential for energy saving and emission reduction.
要降低排烟温度，需要在锅炉的尾部烟道设置可以实现烟气深度冷却的热交换装置，即烟气深度冷却器，要进行有效的烟气深度冷却回收余热必须解决烟气中腐蚀性气体凝结引起的低温腐蚀问题。电站锅炉的低温腐蚀是指热交换器受热面、烟道、风机壁面金属温度(以下称壁温)低于烟气酸露点时，烟气中的酸性氧化物和水蒸气结合成酸蒸汽并在金属壁面上凝结，并对热交换管受热面或金属壁面产生低温腐蚀。对于锅炉来说低温腐蚀多发生在空预器冷端、静电除尘器、烟气深度冷却器、脱硫塔、尾部烟道及烟囱等。锅炉中的低温腐蚀通常是指由烟气中的SO3引起的硫酸腐蚀，这主要是因为SO3和水蒸气结合形成的酸露点比较高。低温腐蚀严重时，会导致运行中经常会因烟气深度冷却器和空气预热器的严重堵灰而被迫降低锅炉负荷、或因低温腐蚀穿透护板而造成大量漏风。低温腐蚀会加重积灰，积灰使烟气通道堵塞，引风阻力增加，降低锅炉出力，甚至引起被迫停炉。低温腐蚀严重将导致大量热交换器受热面的更换和烟道更换，造成经济上的巨大损失。准确判断低温腐蚀发生的温度，对锅炉在安全运行条件下尽可能降低烟温具有重要意义。To reduce the exhaust gas temperature, it is necessary to install a heat exchange device in the tail flue of the boiler that can realize the deep cooling of the flue gas, that is, the deep flue gas cooler. To perform effective deep cooling of the flue gas and recover waste heat, it is necessary to solve the corrosive gas in the flue gas Low temperature corrosion problems caused by condensation. The low-temperature corrosion of power plant boilers means that when the metal temperature of the heating surface of the heat exchanger, the flue, and the wall surface of the fan (hereinafter referred to as the wall temperature) is lower than the acid dew point of the flue gas, the acidic oxides and water vapor in the flue gas combine to form acid vapor and Condensation on the metal wall and low-temperature corrosion on the heating surface of the heat exchange tube or the metal wall. For boilers, low-temperature corrosion mostly occurs at the cold end of the air preheater, electrostatic precipitator, flue gas deep cooler, desulfurization tower, tail flue and chimney, etc. Low-temperature corrosion in boilers usually refers to sulfuric acid corrosion caused by SO 3 in flue gas, mainly because the acid dew point formed by the combination of SO 3 and water vapor is relatively high. When the low-temperature corrosion is serious, it will often cause the boiler load to be reduced due to the severe blockage of the flue gas deep cooler and air preheater during operation, or cause a large amount of air leakage due to low-temperature corrosion penetrating the guard plate. Low-temperature corrosion will aggravate ash accumulation, which will block the flue gas channel, increase the resistance of induced wind, reduce the output of the boiler, and even cause the forced shutdown of the boiler. Severe low-temperature corrosion will lead to the replacement of a large number of heat exchanger heating surfaces and flue replacement, resulting in huge economic losses. Accurately judging the temperature at which low-temperature corrosion occurs is of great significance for reducing the flue gas temperature of the boiler as much as possible under safe operating conditions.
国外20世纪40年代中期就发现了低温腐蚀并做了大量低温腐蚀性能研究工作。20世纪70年代的能源危机迫使各国开始降低排烟温度，提高锅炉热效率，节约能源，之后，低温腐蚀的研究重点转移到了低温腐蚀机理和低温腐蚀速率的性能研究上，主要是通过试验来确定受热面所能承受的最低排烟温度，实验方法主要有：酸浸泡试验、实验室模拟试验及运行现场腐蚀试验。由于硫酸浸泡试验、实验室模拟试验比现场试验简单，因此，人们将大量的精力放在了硫酸浸泡试验中，并得出了大量的研究成果；但酸浸泡试验的腐蚀机理和实际烟气冷却器现场的腐蚀机理存在很大不同，其研究结果难以指导实际运行的烟气冷却器；而实验室模拟试验主要是搭建模拟烟气气氛的低温腐蚀试验台，通过控制烟气温度、烟气中SO3含量、不同金属材料种类及金属壁面温度来研究低温腐蚀性能，实验室模拟试验能较精确的调节各种因素，但腐蚀时间短且无法有效模拟灰分存在对酸露点和硫酸结露腐蚀机理的影响，这导致了实验结果与实际结果差异较大。最后，研究人员不得不到锅炉实际运行现场进行低温腐蚀试验，现场工业试验得出的结果接近于生产实际，具有重要的参考价值，为锅炉设计者提供了有价值的锅炉设计经验。In the mid-1940s abroad, low-temperature corrosion was discovered and a lot of research work on low-temperature corrosion performance was done. The energy crisis in the 1970s forced countries to reduce exhaust gas temperature, improve boiler thermal efficiency, and save energy. After that, the research focus of low-temperature corrosion shifted to the performance research of low-temperature corrosion mechanism and low-temperature corrosion rate, mainly through experiments. The minimum exhaust gas temperature that the surface can withstand, the experimental methods mainly include: acid immersion test, laboratory simulation test and operational field corrosion test. Because the sulfuric acid immersion test and laboratory simulation test are simpler than the field test, people put a lot of energy into the sulfuric acid immersion test and obtained a lot of research results; but the corrosion mechanism of the acid immersion test and the actual flue gas cooling The corrosion mechanism on site is very different, and the research results are difficult to guide the actual operation of the flue gas cooler; while the laboratory simulation test is mainly to build a low-temperature corrosion test bench to simulate the flue gas atmosphere, by controlling the flue gas temperature, flue gas SO 3 content, different types of metal materials and metal wall temperature are used to study the low-temperature corrosion performance. The laboratory simulation test can adjust various factors more accurately, but the corrosion time is short and cannot effectively simulate the corrosion mechanism of acid dew point and sulfuric acid condensation caused by the presence of ash. This leads to a large difference between the experimental results and the actual results. In the end, the researchers had to go to the actual operation site of the boiler to conduct low-temperature corrosion tests. The results obtained from the field industrial tests were close to the actual production, which had important reference value and provided valuable boiler design experience for boiler designers.
过去苏联锅炉教科书中提供的电站锅炉酸露点的计算公式之所以被广大的锅炉设计人员所接受，就是因为该酸露点公式来自现场试验的生产实际，但是，过去的现场工业腐蚀试验实验装置普遍采用欧洲人设计的U型管式双管或多管结构，结构复杂，该结构需要破坏烟道才能在烟道上安装测试，试验之后，需要破坏烟道才能取出试验管段，造成现场的辅助准备工作量很大、试验周期长，有时还要在机组停修期间才能安装、拆卸，给锅炉换热器低温腐蚀研究工作带来了很大的困难。本专利申请人基于以上背景技术发明了一种用于烟气低温腐蚀性能研究的实验装置(CN 202041446 U),该装置可不停炉随插随用,解决了换热器管低温腐蚀实验的难题；利用该装置首次在我国600MW和1000MW机组上完成了6种钢材、表面渗层和表面涂层的现场低温腐蚀实验，提出有限腐蚀速率设计及腐蚀防控技术，解决了积灰和低温腐蚀耦合引致堵塞、爆管停炉的重大技术难题，实现了烟气深度冷却器实时长周期安全高效运行。但是以上实验装置只是解决了材料低温腐蚀速率的短期实验难题，而长期低温腐蚀速率是根据短期实验的腐蚀速率平均或外推的数值，实际运行的烟气冷却器的长期的真实腐蚀速率仍然无法得知，机组正常运行时，又不能定期割取烟气冷却器的实际运行管段进行离线检测以获取实际运行管段的低温腐蚀速率；更为困难的是，由于硫酸露点腐蚀和积灰的协同作用，没有一种检测方法能够在线监测实际换热器管束的低温腐蚀状况，因此，必须发明一种能够同步监测烟气冷却器低温腐蚀过程及状态的装置，该装置可以同步处于和烟气冷却器相同的工作状态(包括煤质、负荷等)，而在机组定期检修时又能截取该装置的腐蚀管段进行离线检测，从而获得换热管的低温腐蚀速率，以上就是本发明的背景。In the past, the formula for calculating the acid dew point of power plant boilers provided in the Soviet boiler textbooks was accepted by the majority of boiler designers because the acid dew point formula came from the actual production of field tests. However, the past field industrial corrosion test equipment generally used The U-shaped double-pipe or multi-pipe structure designed by Europeans has a complex structure. This structure needs to destroy the flue to install and test on the flue. After the test, the flue needs to be destroyed to take out the test pipe section, resulting in auxiliary preparation work on site. It is very large, the test period is long, and sometimes it can only be installed and disassembled during the shutdown of the unit, which brings great difficulties to the low-temperature corrosion research of boiler heat exchangers. Based on the above background technology, the applicant of this patent invented an experimental device (CN 202041446 U) for the research on the low-temperature corrosion performance of flue gas. ;Using this device for the first time in my country's 600MW and 1000MW units to complete the on-site low-temperature corrosion experiments of 6 kinds of steel, surface penetration layer and surface coating, proposed limited corrosion rate design and corrosion prevention and control technology, solved the coupling of dust accumulation and low-temperature corrosion The major technical problems caused by blockage and tube explosion shutdown have realized the safe and efficient operation of the flue gas deep cooler in real time and for a long period. However, the above experimental devices only solve the short-term experimental problem of the low-temperature corrosion rate of materials, and the long-term low-temperature corrosion rate is based on the average or extrapolated value of the corrosion rate of the short-term experiment. It is known that when the unit is in normal operation, the actual operating pipe section of the flue gas cooler cannot be regularly cut for off-line testing to obtain the low-temperature corrosion rate of the actual operating pipe section; what is more difficult is that due to the synergistic effect of sulfuric acid dew point corrosion , there is no detection method that can monitor the low-temperature corrosion status of the actual heat exchanger tube bundle online. Therefore, it is necessary to invent a device that can simultaneously monitor the low-temperature corrosion process and state of the flue gas cooler. The same working conditions (including coal quality, load, etc.), but during the regular maintenance of the unit, the corroded pipe section of the device can be intercepted for off-line detection, thereby obtaining the low-temperature corrosion rate of the heat exchange tube. The above is the background of the present invention.
发明内容Contents of the invention
本发明的目的在于提供一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置，可随时插入锅炉尾部烟道以实现烟气冷却器换热管的低温腐蚀过程及状态的同步在线监测，机组定期检修时又能截取该装置的腐蚀管段进行离线检测，从而获得换热管束的低温腐蚀速率。The purpose of the present invention is to provide a synchronous online monitoring device for the low-temperature corrosion process and state of the flue gas cooler, which can be inserted into the tail flue of the boiler at any time to realize the synchronous online monitoring of the low-temperature corrosion process and state of the heat exchange tubes of the flue gas cooler. During the regular maintenance of the unit, the corroded pipe section of the device can be intercepted for off-line detection, so as to obtain the low-temperature corrosion rate of the heat exchange tube bundle.
为了达到上述目的，本发明所采用的技术方案如下：In order to achieve the above object, the technical scheme adopted in the present invention is as follows:
一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置，包括至少一个恒壁温换热管3，所述恒壁温换热管3从上至下依次由冷凝段、绝热段及蒸发段组成，监测时，所述恒壁温换热管3的蒸发段置于尾部烟道1内，且蒸发段的外壁通过导线连接有热电偶2，所述恒壁温换热管3的冷凝段外连接有强制对流散热的套管4，所述强制对流散热的套管4底部为开口，顶部开孔并与鼓风机7通过空气管路6连接，所述每个强制对流散热的套管4支路上的空气管路6上均设有调节阀5以调控空气流量以确保恒壁温换热器得到适度冷却；所述恒壁温换热管3内有用于换热的介质。A synchronous online monitoring device for the low-temperature corrosion process and state of a flue gas cooler, including at least one constant wall temperature heat exchange tube 3, the constant wall temperature heat exchange tube 3 consists of a condensation section, an adiabatic section, and an evaporation section from top to bottom. When monitoring, the evaporation section of the constant wall temperature heat exchange tube 3 is placed in the tail flue 1, and the outer wall of the evaporation section is connected with a thermocouple 2 through a wire, and the condensation of the constant wall temperature heat exchange tube 3 The outside of the segment is connected with a casing 4 for forced convection heat dissipation. The bottom of the casing 4 for forced convection heat dissipation is open, and the top is perforated and connected to the blower 7 through an air pipeline 6. Each of the casing pipes 4 for forced convection heat dissipation The air pipelines 6 on the branch roads are provided with regulating valves 5 to regulate the air flow to ensure proper cooling of the constant wall temperature heat exchanger; the constant wall temperature heat exchange tubes 3 contain a medium for heat exchange.
参考实际工作的烟气冷却器的最低金属壁温，根据负荷变动范围设置一组上、中、下3种金属壁温变化的恒壁温换热管3作为一组，然后根据机组实际运行需要检修的次数n，设置n组需要离线检测的恒壁温换热管3管组数。Referring to the minimum metal wall temperature of the actual working flue gas cooler, set a group of constant wall temperature heat exchange tubes 3 with upper, middle and lower metal wall temperature changes as a group according to the load fluctuation range, and then according to the actual operation needs of the unit For the number of inspections n, set the number of n groups of constant wall temperature heat exchange tubes that need to be detected offline.
所述恒壁温换热管3的冷凝段外与强制对流散热的套管4之间采用焊接于强制对流散热的套管4内沿圆周360°均布的3个固定的纵向肋片11进行定位。Between the outside of the condensation section of the constant wall temperature heat exchange tube 3 and the casing 4 for forced convection heat dissipation, three fixed longitudinal fins 11 welded in the casing 4 for forced convection heat dissipation and uniformly distributed along the circumference of 360° position.
所述恒壁温换热管3内用于换热的介质为水或沸点处于换热器工作温度范围内的工质；恒壁温换热管3内充填的工质沸点温度由其管内压力惟一确定，而该沸点温度能够设置与换热器金属外壁面工作温度相同。The medium used for heat exchange in the constant wall temperature heat exchange tube 3 is water or a working medium whose boiling point is within the working temperature range of the heat exchanger; the boiling point temperature of the working medium filled in the constant wall temperature heat exchange tube 3 is determined by the pressure The only one is determined, and the boiling point temperature can be set to be the same as the working temperature of the metal outer wall of the heat exchanger.
监测时，所述恒壁温换热管3的蒸发段置于尾部烟道1内，恒壁温换热管3通过法兰12与烟道外壁13连接。During monitoring, the evaporation section of the constant wall temperature heat exchange tube 3 is placed in the tail flue 1 , and the constant wall temperature heat exchange tube 3 is connected to the outer wall 13 of the flue through a flange 12 .
所述恒壁温换热管3能够在锅炉运行特定时间后，且在不停炉的状态下进行拆卸、安装，而不破坏锅炉本体及换热器本体结构。The constant wall temperature heat exchange tube 3 can be disassembled and installed in the state of non-stop boiler after the boiler has been running for a certain period of time without damaging the structure of the boiler body and the heat exchanger body.
本发明的有益效果在于：The beneficial effects of the present invention are:
(1)本发明的一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置结构简单，无复杂连接，实施起来也比较方便且结果可靠。(1) A synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention has a simple structure, no complicated connections, and is relatively convenient to implement and the result is reliable.
(2)本发明的用于烟气冷却器低温腐蚀过程及状态的同步在线监测装置具有金属壁温稳定的优势，能真实反映出尾部烟道烟气冷却器的低温腐蚀过程和状态，同时可离线检测得到烟气换热器的低温腐蚀速率。(2) The synchronous online monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention has the advantage of stable metal wall temperature, can truly reflect the low-temperature corrosion process and state of the flue gas cooler at the tail flue, and can simultaneously The low-temperature corrosion rate of the flue gas heat exchanger was obtained by off-line detection.
(3)本发明的用于烟气冷却器低温腐蚀过程及状态的同步在线监测装置可在锅炉运行中，即不停炉状态下进行安装和拆卸。(3) The synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention can be installed and disassembled when the boiler is running, that is, in a non-stop state.
(4)本发明的用于烟气冷却器低温腐蚀过程及状态的同步在线监测装置，可在烟道内设置一系列不同温度、不同腐蚀时间的换热管，更加全面地了解烟气冷却器管路的低温腐蚀状况。(4) The synchronous online monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention can set a series of heat exchange tubes with different temperatures and different corrosion times in the flue, so as to understand the flue gas cooler tube more comprehensively The low temperature corrosion condition of the road.
(5)本发明的用于烟气冷却器低温腐蚀过程及状态的同步在线监测装置，能够提供精确可靠的低温腐蚀发生的温度，为电厂加装烟气冷却器确定最低的安全运行温度，最大程度地进行余热利用，节约燃煤。(5) The synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention can provide accurate and reliable low-temperature corrosion occurrence temperature, and determine the lowest safe operating temperature for the installation of the flue gas cooler in the power plant, the maximum Utilize waste heat to the greatest extent and save coal.
附图说明Description of drawings
图1是本发明一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置的结构示意图。Fig. 1 is a structural schematic diagram of a synchronous on-line monitoring device for the low-temperature corrosion process and state of a flue gas cooler according to the present invention.
图2是本发明的一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置的强制散热的套管内部的定位结构。Fig. 2 is a positioning structure inside the casing for forced heat dissipation of a synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention.
图3为本发明的一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置的恒壁温换热管和尾部烟道的连接方式。Fig. 3 is a connection mode of the constant wall temperature heat exchange tube and the tail flue of a synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention.
图4是本发明的一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置的恒壁温换热管工作原理示意图。Fig. 4 is a schematic diagram of the working principle of the constant wall temperature heat exchange tube of a synchronous on-line monitoring device for the low-temperature corrosion process and state of the flue gas cooler of the present invention.
图中，1.尾部烟道，2.热电偶，3.恒壁温换热管，4.强制散热的套管，5.调节阀，6.空气管路，7.鼓风机，8.蒸气，9.冷凝液，11.肋片，12.法兰，13.烟道外壁。In the figure, 1. Tail flue, 2. Thermocouple, 3. Constant wall temperature heat exchange tube, 4. Forced cooling sleeve, 5. Regulating valve, 6. Air pipeline, 7. Blower, 8. Steam, 9. Condensate, 11. Fin, 12. Flange, 13. Outer wall of the flue.
具体实施方式detailed description
下面结合附图和具体实施方式对本发明进行详细说明。The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.
如图1所示，本发明一种烟气冷却器低温腐蚀过程及状态的同步在线监测装置，包括至少一个恒壁温换热管3，所述恒壁温换热管3从上至下依次由冷凝段、绝热段及蒸发段组成，监测时，所述恒壁温换热管3的蒸发段置于尾部烟道1内，且蒸发段的外壁通过导线连接有热电偶2，所述恒壁温换热管3的冷凝段外连接有强制对流散热的套管4，所述强制对流散热的套管4底部为开口，顶部开孔并与鼓风机7通过空气管路6连接，所述每个强制对流散热的套管4支路上的空气管路6上均设有调节阀5以调控空气流量；所述恒壁温换热管3内有用于换热的介质。As shown in Figure 1, a synchronous online monitoring device for the low-temperature corrosion process and state of a flue gas cooler in the present invention includes at least one constant wall temperature heat exchange tube 3, and the constant wall temperature heat exchange tube 3 is sequentially arranged from top to bottom It consists of a condensation section, an adiabatic section and an evaporation section. During monitoring, the evaporation section of the constant wall temperature heat exchange tube 3 is placed in the tail flue 1, and the outer wall of the evaporation section is connected with a thermocouple 2 through a wire. The condensing section of the wall temperature heat exchange tube 3 is connected with a casing 4 for forced convection heat dissipation. The bottom of the casing 4 for forced convection heat dissipation is an opening, and the top is opened and connected to the blower 7 through an air pipeline 6. Each of the A regulating valve 5 is provided on the air pipeline 6 on the branch road of the casing 4 for forced convection heat dissipation to regulate the air flow; the constant wall temperature heat exchange tube 3 has a medium for heat exchange.
作为本发明的优选实施方式，参考实际工作的烟气冷却器的最低金属壁温，根据负荷变动范围设置一组上、中、下3种金属壁温变化的恒壁温换热管3作为一组，然后根据机组实际运行需要检修的次数n，设置n组需要离线检测的恒壁温换热管3管组数。As a preferred embodiment of the present invention, with reference to the minimum metal wall temperature of the actual working flue gas cooler, a group of constant wall temperature heat exchange tubes 3 with upper, middle and lower metal wall temperature changes are set as a set according to the load fluctuation range. group, and then according to the number n of overhauls required for the actual operation of the unit, set the number of n groups of constant wall temperature heat exchange tubes that need to be detected offline.
单根恒壁温换热管3的内壁通过管内工作介质温度确定金属壁温；正常工作状态下，恒壁温换热管3工作温度由管内压力唯一确定。The inner wall of a single constant wall temperature heat exchange tube 3 determines the metal wall temperature by the temperature of the working medium in the tube; under normal working conditions, the working temperature of the constant wall temperature heat exchange tube 3 is uniquely determined by the pressure inside the tube.
作为本发明的优选实施方式，所述恒壁温换热管3内用于换热的介质为水或沸点处于换热器工作温度范围内的工质。As a preferred embodiment of the present invention, the medium used for heat exchange in the constant wall temperature heat exchange tube 3 is water or a working fluid whose boiling point is within the working temperature range of the heat exchanger.
如图2所示，作为本发明的优选实施方式，所述恒壁温换热管3的冷凝段外与强制对流散热的套管4之间采用焊接于强制对流散热的套管4内沿圆周360°均布的3个固定的纵向肋片11进行定位。As shown in Figure 2, as a preferred embodiment of the present invention, between the outside of the condensing section of the constant wall temperature heat exchange tube 3 and the sleeve 4 for forced convection heat dissipation, a tube welded to the inside of the sleeve 4 for forced convection heat dissipation is adopted. 3 fixed longitudinal ribs 11 uniformly distributed in 360° are positioned.
如图3所示，作为本发明的优选实施方式，监测时，所述恒壁温换热管3的蒸发段置于尾部烟道1内，恒壁温换热管3通过法兰12与烟道外壁13连接。As shown in Figure 3, as a preferred embodiment of the present invention, during monitoring, the evaporation section of the constant wall temperature heat exchange tube 3 is placed in the tail flue 1, and the constant wall temperature heat exchange tube 3 is connected to the flue gas through the flange 12. The outer wall 13 of the road is connected.
实施例Example
恒壁温换热管3内填充有用于换热的工作介质水，或采用介质沸点处于换热器工作温度范围内的其他工质，恒壁温换热管3的管内压力确定时，其内部的工作介质的饱和温度也唯一确定，从而保证了恒壁温换热管3管壁温度的稳定；鼓风机7的将高速气流通过空气管路6送入强制散热的套管4内，通过调节阀5调控空气流量；恒壁温换热管3冷凝段与通入套管4的空气进行换热。The constant wall temperature heat exchange tube 3 is filled with water as the working medium for heat exchange, or other working fluid whose boiling point is within the working temperature range of the heat exchanger. When the internal pressure of the constant wall temperature heat exchange tube 3 is determined, its internal The saturation temperature of the working medium is also uniquely determined, thereby ensuring the stability of the wall temperature of the constant wall temperature heat exchange tube 3; the blower 7 sends the high-speed airflow through the air pipeline 6 into the casing 4 for forced heat dissipation, and through the regulating valve 5 Regulating the air flow rate; the constant wall temperature heat exchange tube 3 condensing section exchanges heat with the air passing through the casing 4 .
如图1和图4所示，本发明的工作原理为：在烟气流动方向上，将恒壁温换热管3的蒸发段设置于尾部烟道1中，恒壁温换热管3的蒸发段直接在烟气气氛中进行腐蚀，恒壁温换热管3内的液态工作介质受热蒸发形成蒸气8，蒸气8上行经过绝热段到达冷凝段，在冷凝段冷凝形成冷凝液9，冷凝液9沿壁面回到蒸发段。如此循环往复实现恒壁温换热管3的壁温恒定。利用鼓风机7实现空气与恒壁温换热管3冷凝段的强制对流换热，并通过调节阀5实现不同换热量，使不同温度的恒壁温换热管3内工作介质在冷凝段内冷凝。As shown in Figure 1 and Figure 4, the working principle of the present invention is: in the flue gas flow direction, the evaporation section of the constant wall temperature heat exchange tube 3 is arranged in the tail flue 1, and the constant wall temperature heat exchange tube 3 The evaporating section is corroded directly in the flue gas atmosphere, the liquid working medium in the constant wall temperature heat exchange tube 3 is heated and evaporated to form steam 8, the steam 8 goes up through the adiabatic section to the condensing section, and condenses in the condensing section to form condensate 9, the condensate 9 Return to the evaporation section along the wall. The wall temperature of the constant wall temperature heat exchange tube 3 is kept constant by reciprocating in this way. Use the blower 7 to realize the forced convection heat exchange between the air and the condensing section of the constant wall temperature heat exchange tube 3, and realize different heat transfer through the regulating valve 5, so that the working medium in the constant wall temperature heat exchange tube 3 of different temperatures is in the condensing section condensation.
本发明属用于烟气冷却器低温腐蚀过程及状态的同步在线监测的装置，可真实反映不同温度及烟气环境下烟气冷却器的低温腐蚀状况，可以同步模拟换热器管束真实的低温腐蚀过程和状态，运行特定时间后不需要停炉，就可以在线拆卸一组实验管段，并对该实验管段进行离线检测，从而得到该管段的低温腐蚀速率，该腐蚀速率能够代表换热器腐蚀的真实情况，是一种简单、高效、结果真实可靠的、不需要破坏换热器本体就能获知换热器低温腐蚀真实过程及状态的同步在线监测装置。The invention belongs to a device for synchronous on-line monitoring of the low-temperature corrosion process and state of the flue gas cooler, which can truly reflect the low-temperature corrosion status of the flue gas cooler under different temperatures and flue gas environments, and can simultaneously simulate the real low temperature of the heat exchanger tube bundle Corrosion process and state, after running for a certain period of time without stopping the furnace, a group of experimental pipe sections can be disassembled online, and the experimental pipe section can be detected offline to obtain the low-temperature corrosion rate of the pipe section, which can represent the corrosion rate of the heat exchanger It is a simple, efficient, real and reliable synchronous online monitoring device that can know the real process and status of low-temperature corrosion of the heat exchanger without destroying the heat exchanger body.
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