WO2011020334A1 - System for recovering waste heat from flue gas - Google Patents

System for recovering waste heat from flue gas Download PDF

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Publication number
WO2011020334A1
WO2011020334A1 PCT/CN2010/071854 CN2010071854W WO2011020334A1 WO 2011020334 A1 WO2011020334 A1 WO 2011020334A1 CN 2010071854 W CN2010071854 W CN 2010071854W WO 2011020334 A1 WO2011020334 A1 WO 2011020334A1
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WIPO (PCT)
Prior art keywords
phase change
flue gas
low
heat exchanger
regenerative heating
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PCT/CN2010/071854
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French (fr)
Chinese (zh)
Inventor
费广盛
王晓鹏
冯友福
李曙照
Original Assignee
深圳中兴科杨节能环保股份有限公司
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Priority to CN200910109461.1 priority Critical
Priority to CN2009101094611A priority patent/CN101629713B/en
Application filed by 深圳中兴科杨节能环保股份有限公司 filed Critical 深圳中兴科杨节能环保股份有限公司
Publication of WO2011020334A1 publication Critical patent/WO2011020334A1/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/06Arrangements of devices for treating smoke or fumes of coolers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22DPREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/04Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways the tubes having plain outer surfaces, e.g. in vertical arrangement
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22DPREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/12Control devices, e.g. for regulating steam temperature
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0266Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D21/0001Recuperative heat exchangers
    • F28D21/0012Recuperative heat exchangers the heat being recuperated from waste water or from condensates
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/56Heat recovery units
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/30Technologies for a more efficient combustion or heat usage

Abstract

A system for recovering waste heat from flue gas includes a phase change heat exchanger (100), which includes a phase change upper section (1) and a phase change lower section (9) communicated with the phase change upper section (1), and an autocontrol device (200) mounted on the phase change heat exchanger (100). The phase change upper section (1) is connected to a main condensate pipeline (2) in a low pressure regenerative heating system. The phase change lower section (9) is provided in a flue gas passageway. The flow of the condensate in the low pressure regenerative heating system to enter the phase change upper section (1) is controlled by the autocontrol device (200) according to a signal received from a wall temperature tester (6) which is installed on the phase change lower section (9). The condensate is heated after entering into the phase change upper section (1), and the heated condensate enters into the main condensate pipeline (2) once more. The system can save energy and efficiently heat condensate by utilizing waste heat from flue gas.

Description

烟气余热回收系统 技术领域  Flue gas waste heat recovery system
本发明涉及一种烟气余热回收系统,特别是指一种利用锅炉尾部烟气余热 加热凝结水的烟气余热回收系统。 背景技术  The invention relates to a flue gas waste heat recovery system, in particular to a flue gas waste heat recovery system which utilizes waste heat of boiler tail flue gas to heat condensed water. Background technique
众所周知,锅炉尾部烟道排出的高温烟气如果直接排向大气, 不仅污染环 境, 而且不能满足目前对锅炉节能方面的要求。 于是, 如何有效利用锅炉尾部 烟道排出的高温烟气,提供一种节能环保型锅炉已经成为本领域业界人士关心 的问题。  It is well known that high-temperature flue gas discharged from the flue of the boiler tail is directly discharged into the atmosphere, which not only pollutes the environment, but also fails to meet the current requirements for boiler energy conservation. Therefore, how to effectively utilize the high-temperature flue gas discharged from the flue of the boiler tail to provide an energy-saving and environment-friendly boiler has become a concern of people in the field.
目前,锅炉尾部烟气余热广泛被用于对空气及水的加热,如对进入锅炉空 气预热器的冷空气加热, 或是对其他设备或装置中的冷凝水加热等。对于锅炉 回热加热系统中的凝结水, 通常是采用低压加热器对其加热。 然而, 使用低压 加热器需要利用汽轮机抽汽或排汽才能对回热加热系统中的凝结水加热,而抽 汽或排汽需要大量蒸汽, 会造成能源浪费。  At present, the waste heat of the boiler tail is widely used for heating air and water, such as heating cold air entering the boiler air preheater, or heating the condensate in other equipment or equipment. For condensate in a boiler regenerative heating system, it is usually heated by a low pressure heater. However, the use of low-pressure heaters requires the use of steam turbine extraction or exhaust to heat the condensate in the regenerative heating system, while extraction or exhaust requires a large amount of steam, which can result in wasted energy.
此外,在对高温烟气降温对其热量有效利用的同时,还要考虑锅炉设备中 的低温腐蚀问题。  In addition, while the high-temperature flue gas is cooled and its heat is effectively utilized, the low-temperature corrosion problem in the boiler equipment must also be considered.
设置在锅炉尾部的空气预热器等低温受热面的结露问题是造成锅炉设备 低温腐蚀的主要因素, 因此, 要解决这部分尾部受热面的结露问题, 就必须提 高受热面的壁面温度。通常通过采用提高排烟温度或者进风温度的办法减轻锅 炉设备中受热面低温腐蚀问题, 但是这样会造成一定的能源浪费。  The dew condensation problem of the low temperature heating surface such as the air preheater at the rear of the boiler is the main factor causing the low temperature corrosion of the boiler equipment. Therefore, in order to solve the condensation problem of the tail heating surface, the wall surface temperature of the heating surface must be raised. The problem of low temperature corrosion of the heated surface in the boiler equipment is usually reduced by increasing the exhaust gas temperature or the inlet air temperature, but this will result in a certain energy waste.
由此可见, 需要提供一种新型的利用锅炉烟气余热回收节能系统, 不仅可 以对锅炉尾部烟道的烟气余热进行有效利用,而且能有效改善低压加热器因抽 汽做功造成能源浪费的问题。 发明内容  It can be seen that it is necessary to provide a new type of energy-saving system for utilizing boiler flue gas waste heat recovery, which can not only effectively utilize the flue gas waste heat of the boiler tail flue, but also effectively improve the energy waste caused by the steam pump work. . Summary of the invention
本发明所要解决的技术问题是如何有效利用锅炉尾部烟气余热以部分替 代传统低压加热器因需要汽轮机抽汽做功造成能源浪费的问题。  The technical problem to be solved by the present invention is how to effectively utilize the waste heat of the flue gas at the tail of the boiler to partially replace the problem that the conventional low-pressure heater wastes energy due to the need for steam turbine steam extraction work.
本发明所要解决的另一技术问题是在有效利用锅炉尾部高温烟气的同时, 避免锅炉设备被低温腐蚀。 Another technical problem to be solved by the present invention is that while effectively utilizing the high temperature flue gas at the tail of the boiler, Avoid boiler equipment being corroded at low temperatures.
为了解决上述技术问题, 本发明提供一种烟气余热回收系统, 包括一相变 换热器, 所述相变换热器包括一相变上段及一相变下段,还包括一安装于相变 换热器相变上段的自控装置,所述相变换热器的相变上段与一低压回热加热系 统中的主凝结水管路连通, 所述相变换热器的相变下段设置于一烟气通道内, 所述相变下段安装有一壁温测试仪,所述壁温测试仪的信号通过自控装置对进 入相变换热器的相变上段的低压回热加热系统中的凝结水流量进行控制,所述 低压回热加热系统中的凝结水进入相变换热器的相变上段之后被加热,被加热 的凝结水再次进入低压回热加热系统中的主凝结水管路。  In order to solve the above technical problem, the present invention provides a flue gas waste heat recovery system, comprising a phase change heat exchanger, the phase change heat exchanger comprising a phase change upper section and a phase change lower section, and further comprising a phase change transformer The upper part of the heat exchanger phase change upper stage, the phase change upper section of the phase change heat exchanger is connected with the main condensate water pipeline in a low pressure regenerative heating system, and the phase change lower section of the phase change heat exchanger is set in one In the flue gas passage, a wall temperature tester is installed in the lower phase of the phase change, and the signal of the wall temperature tester passes through the self-control device to the condensed water flow in the low-pressure regenerative heating system of the upper phase of the phase change entering the phase change heat exchanger. Control is performed, the condensed water in the low-pressure regenerative heating system is heated after entering the upper phase of the phase change of the phase change heat, and the heated condensed water again enters the main condensate line in the low-pressure regenerative heating system.
本发明烟气余热回收系统中,一方面, 由于相变换热器的相变上段与低压 回热加热系统中的主凝结水管路连通, 其相变下段与烟气通道连通,故可实现 利用烟气余热加热进入相变换热器相变上段的低压回热加热系统中的凝结水, 即相变换热器无需额外抽取蒸汽作功来加热低压回热加热系统中的凝结水,不 仅节省热源, 且有效利用烟气余热。  In the flue gas waste heat recovery system of the present invention, on the one hand, since the phase change upper section of the phase change heat exchanger is in communication with the main condensate water pipeline in the low pressure regenerative heating system, the lower phase of the phase change is in communication with the flue gas passage, so that utilization can be realized The residual heat of the flue gas is heated into the condensed water in the low-pressure regenerative heating system of the upper phase of the phase change heat phase change phase, that is, the phase change heat device does not need to extract steam as work to heat the condensed water in the low-pressure regenerative heating system, thereby saving not only Heat source, and effectively use the residual heat of flue gas.
另一方面,由于自控装置能够对进入相变换热器的相变上段的凝结水流量 进行控制,保证相变换热器的相变下段受热面温度始终高于烟气酸露点,避免 相变换热器发生低温腐蚀。 附图说明  On the other hand, since the automatic control device can control the flow rate of the condensed water in the upper stage of the phase change of the phase change heat exchanger, it is ensured that the phase change of the phase change heat of the phase change heater is always higher than the smoke acid dew point, and the phase change is avoided. The heat exchanger is subject to low temperature corrosion. DRAWINGS
图 1是本发明利用烟气余热回收系统的一较佳实施例的平面结构示意图。 具体实施方式  BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic plan view showing a preferred embodiment of a flue gas waste heat recovery system of the present invention. detailed description
下面结合附图对本发明的烟气余热回收系统的结构进行说明。  The structure of the flue gas waste heat recovery system of the present invention will be described below with reference to the accompanying drawings.
请参阅图 1 , 本发明的烟气余热回收系统主要是利用锅炉尾部烟气余热加 热部分低压回热加热系统中的凝结水,避免传统低压加热器因抽汽做功造成的 能源浪费。  Referring to FIG. 1 , the flue gas waste heat recovery system of the present invention mainly utilizes the condensed water in the low-pressure regenerative heating system of the flue gas waste heat of the boiler tail to avoid the waste of energy caused by the traditional low-pressure heater due to steam extraction work.
所述烟气余热回收系统包括一相变换热器 100及安装于相变换热器 100 的自控装置 200。  The flue gas waste heat recovery system includes a phase change heat exchanger 100 and an automatic control device 200 installed in the phase change heat exchanger 100.
所述相变换热器 100采用分体式结构,其包括一相变上段 1与一相变下段 9。 所述相变下段 9通过蒸汽上升管 30及液体下降管 40与相变上段 1连通。 所述相变下段 9安装于锅炉空气预热器出口的尾部烟气通道上。所述相变上段 1与氐压回热加热系统中的主凝结水管路 2连通, 以便氐压回热加热系统中的 凝结水可以进入相变上段 1与其进行热交换。 The phase change heater 100 employs a split structure including a phase change upper segment 1 and a phase change lower segment 9. The phase change lower section 9 communicates with the phase change upper section 1 through the vapor riser 30 and the liquid downcomer 40. The phase change lower section 9 is mounted on the tail flue gas passage of the boiler air preheater outlet. Upper phase change 1 is in communication with the main condensate line 2 in the regenerative heat heating system so that the condensed water in the regenerative heating system can enter the phase change upper section 1 for heat exchange therewith.
所述相变下段 9包括一相变段下联箱 8、 相变段上联箱 5及位于相变段下 联箱 8与相变段上联箱 5内的若干换热管 7, 每一换热管 7内充有相变工作介 质, 如水等。 在本实施例中, 换热管 7采用螺旋翅片管结构。 但是, 换热管 7 的结构不受此限制, 其还可采用其他结构形式, 只要能实现换热管 7内的相变 工作介质与换热管 7外的烟气进行有效换热即可。  The phase change lower section 9 includes a phase change section lower header box 8, a phase change section upper header box 5, and a plurality of heat exchange tubes 7 located in the phase change section lower header box 8 and the phase change section upper header box 5, each heat exchange tube The tube 7 is filled with a phase change working medium such as water. In the present embodiment, the heat exchange tube 7 employs a spiral finned tube structure. However, the structure of the heat exchange tube 7 is not limited thereto, and other structural forms may be employed as long as the phase change working medium in the heat exchange tube 7 and the flue gas outside the heat exchange tube 7 can be effectively exchanged.
所述相变换热器 100的相变下段 9的最外侧换热管 7的壁面上安装一壁温 测感仪 6, 所述壁温测感仪 6将其温度信号传至自控装置 200的信号输入端。 所述壁温测感仪 6的信号可以通过自控装置 200对进入相变上段 1的低压回热 加热系统中的凝结水流量进行调节,从而通过流入相变上段 1的凝结水的流量 来调节相变下段 9的壁温, 达到控制相变下段 9壁温的目的。  A wall temperature sensor 6 is mounted on the wall surface of the outermost heat exchange tube 7 of the phase change lower section 9 of the phase change heat exchanger 100, and the wall temperature sensor 6 transmits its temperature signal to the automatic control device 200. Signal input. The signal of the wall temperature sensor 6 can be adjusted by the automatic control device 200 to the flow rate of the condensed water entering the low-pressure regenerative heating system of the phase change upper stage 1, thereby adjusting the phase by flowing the flow of the condensed water flowing into the upper stage 1 of the phase change. The wall temperature of the lower section 9 is changed to achieve the purpose of controlling the wall temperature of the lower stage 9 of the phase change.
所述相变换热器 100的相变上段 1采用列管式换热器结构, 然, 其具体结 构不受本实施例的限制。  The phase change upper section 1 of the phase change heat exchanger 100 employs a tubular heat exchanger structure, and the specific structure thereof is not limited by this embodiment.
本发明实施例中在相变换热器 100的相变上段 1与低压回热加热系统中主 凝结水管路 2之间设置一进水管路 50与一出水管路 52。 所述进水管路 50与 出水管路 52分别与主凝结水管路 2连通。 所述主凝结水管路 2分级安装若干 加热器 4, 所述进水管路 50设置于加热器主凝结水管路 2的某一级加热器 4 之后的主凝结水管路 2上。 所述出水管路 52安装于位于某一级温度较高的加 热器 4之后的主凝结水管路 2上。 可以理解的, 进水管路 50可以部分接入凝 结水实现辅助加热器 4加热凝结水,也可以全部接入主凝结水, 即完全通过烟 气余热对低压回热加热系统中的凝结水加热, 而无需加热器 4。 同时进水管路 50的接入口可以为第一级加热器 4的出口, 也可以为第二或第三级加热器 4 的出口, 即可以根据电厂系统需要选择, 而出水管路 52同样根据需要接入到 某一级加热器 4的出口, 在原排烟温度较高时, 可以尽可能将相变换热器 100 的相变上段 1出口的凝结水加热到较高温度, 这样产生的热效率将更高。本发 明实施例中, 加热之后的凝结水经出水管路 52的出口水温可通过分级加热达 到 140摄氏度以上。  In the embodiment of the present invention, a water inlet line 50 and a water outlet line 52 are disposed between the phase change upper section 1 of the phase change heat exchanger 100 and the main condensate water line 2 of the low pressure heat recovery heating system. The water inlet line 50 and the water outlet line 52 are in communication with the main condensate line 2, respectively. The main condensate line 2 is hierarchically installed with a plurality of heaters 4 disposed on the main condensate line 2 after a certain stage heater 4 of the main condensate line 2 of the heater. The water outlet line 52 is installed on the main condensate line 2 after the heater 4 having a higher temperature in a certain stage. It can be understood that the water inlet pipe 50 can be partially connected to the condensed water to realize the auxiliary heater 4 to heat the condensed water, or all of the main condensed water, that is, the condensed water in the low-pressure regenerative heating system can be completely heated by the residual heat of the flue gas. There is no need for heater 4. At the same time, the inlet of the water inlet pipe 50 may be the outlet of the first stage heater 4, or the outlet of the second or third stage heater 4, that is, may be selected according to the needs of the power plant system, and the outlet pipe 52 is also required according to needs. Connected to the outlet of a certain level of heater 4, when the original exhaust temperature is high, the condensate of the phase change upper section 1 of the phase change heat exchanger 100 can be heated to a higher temperature as much as possible, so that the thermal efficiency will be higher. In the embodiment of the present invention, the condensed water after heating may be heated to a temperature of 140 degrees Celsius or more through the outlet water passing through the outlet pipe 52.
所述相变换热器 100的相变上段 1的进水管路 50上安装一凝结水流量调 节阀 3 , 即进入相变上段 1的凝结水流量可通过凝结水流量调节阀 3控制。 所 述凝结水流量调节阀 3的控制信号来自自控装置 200的信号输出端。 本发明烟气余热回收系统的工作过程如下所述: 首先,锅炉尾部烟道的烟 气余热进入相变换热器的 100相变下段 9, 与相变下段 9内的换热管 7进行充 分的热交换,相变下段 9的换热管 7由于吸收烟气余热而使换热管 7内的相变 工作介质由液态变为汽态, 此时, 烟气余热因与换热管 7热交换而降温。 温度 明显被降低的烟气余热经相变下段 9接入除尘器;接着,相变下段 9内的蒸汽 顺着蒸汽上升管 30进入相变换热器 100的相变上段 1 ; 与此同时, 低压回热 加热系统中的凝结水经进水管路 50进入相变上段 1的列管内并与管外蒸汽热 交换, 凝结水即被加热, 同时蒸汽因放热而变为冷凝水并沿着液体下降管 40 回流到相变下段 9, 加热后的凝结水经出水管路 52之后进入主凝结水管路 2 上, 至此便完成利用锅炉烟气余热对低压回热加热系统中的凝结水加热目的。 A condensed water flow regulating valve 3 is installed in the water inlet pipe 50 of the phase change upper section 1 of the phase change heat exchanger 100, that is, the condensed water flow rate entering the phase change upper section 1 can be controlled by the condensed water flow regulating valve 3. The control signal of the condensate flow regulating valve 3 is from the signal output end of the automatic control device 200. The working process of the flue gas waste heat recovery system of the present invention is as follows: First, the flue gas waste heat of the boiler tail flue enters the 100 phase transition lower section 9 of the phase change heat exchanger, and is fully performed with the heat exchange tube 7 in the phase change lower section 9. The heat exchange, phase change of the heat exchange tube 7 of the lower section 9 causes the phase change working medium in the heat exchange tube 7 to change from a liquid state to a vapor state due to absorption of waste heat of the flue gas. At this time, the residual heat of the flue gas is heated by the heat exchange tube 7 Exchange and cool down. The waste heat of the flue gas, which is obviously lowered in temperature, is connected to the precipitator via the phase change lower section 9; then, the vapor in the lower stage of the phase change enters the phase change upper section 1 of the phase change heat exchanger 100 along the vapor riser pipe 30; The condensed water in the low-pressure regenerative heating system enters the column of the phase change upper section 1 through the water inlet line 50 and exchanges heat with the steam outside the tube, and the condensed water is heated, and the steam becomes condensed water and acts along the liquid due to the heat release. The downcomer 40 is returned to the lower stage of the phase change, and the heated condensed water enters the main condensate line 2 through the water outlet line 52, thereby completing the purpose of heating the condensed water in the low pressure heat recovery heating system by utilizing the residual heat of the boiler flue gas.
上述相变换热器 100的相变下段 9与相变上段 1的整个换热过程,就是相 变工作介质发生蒸发与冷凝的相变过程,而相变工作介质在一定压力下相变状 况的温度是恒定的。此时,相变换热器 100的相变下段 9与相变上段 1在相变 状况下, 换热管 7受热面温度近似等于相变温度。 故, 相变换热器 100的相变 下段 9的壁温处于整体可调节的状态。  The whole heat exchange process of the phase change lower section 9 and the phase change upper section 1 of the phase change heat exchanger 100 is a phase change process in which the phase change working medium undergoes evaporation and condensation, and the phase change work medium undergoes a phase change state under a certain pressure. The temperature is constant. At this time, in the phase change state of the phase change lower section 9 and the phase change upper section 1 of the phase change heat exchanger 100, the heat transfer surface temperature of the heat exchange tube 7 is approximately equal to the phase transition temperature. Therefore, the phase change of the phase change lower section 9 of the phase change heat exchanger 100 is in an overall adjustable state.
由于相变换热器 100的相变下段 9安装有壁温测感仪 6, 其能通过自控装 置 200对相变下段 9的壁温调节,保证相变下段 9的壁温始终高于烟气的酸露 点。 即是说, 当相变下段 9的壁温低于烟气的酸露点时, 可以通过凝结水流量 调节阀 3调节进入相变上段 1的凝结水流量,实现对相变下段 9的壁温进行控 制, 保证其始终高于烟气的酸露点, 避免相变换热器 100受低温腐蚀。  Since the phase change lower section 9 of the phase change heat exchanger 100 is equipped with the wall temperature sensor 6 , the wall temperature of the phase change lower section 9 can be adjusted by the automatic control device 200 to ensure that the wall temperature of the phase change lower section 9 is always higher than the flue gas. The acid dew point. That is to say, when the wall temperature of the phase change lower section 9 is lower than the acid dew point of the flue gas, the condensed water flow rate entering the phase change upper section 1 can be adjusted by the condensed water flow regulating valve 3 to realize the wall temperature of the lower phase change phase 9 Control, to ensure that it is always higher than the acid dew point of the flue gas, to avoid the phase change heat exchanger 100 from low temperature corrosion.
相比于现有技术, 本发明实施例中, 由于相变换热器 100取代传统的低压 加热器,通过利用锅炉尾部的烟气余热加热低压回热加热系统中的凝结水, 即 相变换热器 100无需像传统的低压加热器通过汽轮机抽汽或排气获得热源,不 仅节省能源, 且对锅炉尾部的烟气余热有效利用, 一举两得。  Compared with the prior art, in the embodiment of the present invention, since the phase change heat exchanger 100 replaces the traditional low-pressure heater, the condensed water in the low-pressure regenerative heating system is heated by utilizing the residual heat of the flue gas at the tail of the boiler, that is, the phase change The heat exchanger 100 does not need to obtain a heat source by steam extraction or exhausting from a conventional low-pressure heater, which not only saves energy, but also effectively utilizes the residual heat of the flue gas at the tail of the boiler.
可以理解的,本发明实施例中的相变换热器 100的具体结构不受本实施例 的限制,即只要能满足利用锅炉烟气余热对低压回热加热系统中的凝结水进行 加热的其他热交换设备或装置均可。  It can be understood that the specific structure of the phase change heat exchanger 100 in the embodiment of the present invention is not limited by the embodiment, that is, as long as the condensed water in the low-pressure regenerative heating system is heated by utilizing the waste heat of the boiler flue gas. Hot swap devices or devices are available.
以上仅为本发明的优选实施案例而已,并不用于限制本发明,对于本领域 的技术人员来说, 本发明可以有各种更改和变化。凡在本发明的精神和原则之 内,所作的任何修改、等同替换、改进等, 均应包含在本发明的保护范围之内。  The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

权 利 要 求 Rights request
1、 一种烟气余热回收系统, 包括一相变换热器, 所述相变换热器包括一 相变上段及一相变下段,其特征在于:还包括一安装于相变换热器的自控装置, 所述相变换热器的相变上段与一低压回热加热系统中的主凝结水管路连通,所 述相变换热器的相变下段设置于一烟气通道内,所述相变换热器的相变下段安 装有一壁温测试仪,所述壁温测试仪的信号通过自控装置对进入相变换热器的 相变上段的低压回热加热系统中的凝结水流量进行控制,所述低压回热加热系 统中的凝结水进入相变换热器的相变上段之后被加热,被加热的凝结水再次进 入低压回热加热系统中的主凝结水管路。 A flue gas waste heat recovery system comprising a phase change heat exchanger, the phase change heat exchanger comprising a phase change upper section and a phase change lower section, characterized in that: further comprising a phase change heat exchanger The automatic control device, the phase change upper section of the phase change heat exchanger is connected with the main condensate water pipeline in a low-pressure regenerative heating system, and the phase change lower section of the phase change heat exchanger is disposed in a flue gas passage. The phase change lower section of the phase change heat exchanger is equipped with a wall temperature tester, and the signal of the wall temperature tester passes through the self-control device to the condensed water flow in the low-pressure regenerative heating system of the upper phase change phase of the phase change heat exchanger. Control is performed, the condensed water in the low-pressure regenerative heating system is heated after entering the upper phase of the phase change of the phase change heat, and the heated condensed water again enters the main condensate line in the low-pressure regenerative heating system.
2、 根据权利要求 1所述的烟气余热回收系统, 其特征在于: 所述相变换 热器的相变上段与低压回热加热系统中的主凝结水管路之间连通一进水管路, 所述进水管路上安装一凝结水流量调节阀,所述凝结水流量调节阀与自控装置 连通,进入相变换热器的相变上段内的凝结水流量通过自控装置及凝结水流量 调节阀调节。  2. The flue gas waste heat recovery system according to claim 1, wherein: a phase change upper section of the phase change heat exchanger and a main condensate water pipeline in the low pressure regenerative heating system are connected to a water inlet pipeline, a condensed water flow regulating valve is installed on the inlet pipe, and the condensed water flow regulating valve is connected with the automatic control device, and the condensed water flow in the upper phase of the phase change entering the phase change heat is regulated by the automatic control device and the condensed water flow regulating valve .
3、 根据权利要求 2所述的烟气余热回收系统, 其特征在于: 所述相变换 热器的相变上段与低压回热加热系统中的主凝结水管路之间还连通一出水管 路, 所述低压回热加热系统中的凝结水由相变换热器的相变上段加热后, 经出 水管路回流至低压回热加热系统中的主凝结水管路上。  3. The flue gas waste heat recovery system according to claim 2, wherein: a phase change upper section of the phase change heat exchanger and a main condensate water line in the low pressure regenerative heating system are further connected to a water outlet pipeline. The condensed water in the low-pressure regenerative heating system is heated by the phase change upper section of the phase change heater, and is returned to the main condensate water pipe in the low-pressure regenerative heating system through the water outlet pipe.
4、 根据权利要求 3所述的烟气余热回收系统, 其特征在于: 所述低压回 热加热系统中的主凝结水管路上分级设有若干加热器,所述进水管路安装在不 同分级的加热器之后。  4. The flue gas waste heat recovery system according to claim 3, wherein: the main condensate water pipe in the low-pressure regenerative heating system is hierarchically provided with a plurality of heaters, and the water inlet pipes are installed in different stages of heating. After the device.
5、 根据权利要求 4所述的烟气余热回收系统, 其特征在于: 所述出水管 路安装于低压回热加热系统中的主凝结水管路某一级加热器之后。  The flue gas waste heat recovery system according to claim 4, wherein the outlet pipe is installed after a certain stage heater of the main condensate line in the low-pressure regenerative heating system.
6、 根据权利要求 1所述的烟气余热回收系统, 其特征在于: 所述相变换 热器的相变下段包括一相变段下联箱、一相变段上联箱及位于相变段下联箱与 相变段上联箱的若干换热管, 所述壁温测试仪安装于换热管上。  6. The flue gas waste heat recovery system according to claim 1, wherein: the phase change lower section of the phase change heatr comprises a phase change section lower header, a phase change section upper header, and a phase change section. The lower header and the plurality of heat exchange tubes of the junction box of the phase change section, the wall temperature tester is installed on the heat exchange tube.
7、 根据权利要求 6所述的烟气余热回收系统, 其特征在于: 所述壁温测 试仪与自控装置连通,所述壁温测试仪的信号通过自控装置对进入相变换热器 的相变上段的低压回热加热系统中的主凝结水流量进行调节。  7. The flue gas waste heat recovery system according to claim 6, wherein: the wall temperature tester is in communication with the automatic control device, and the signal of the wall temperature tester passes through the phase of the phase change heat device through the automatic control device. The main condensate flow rate in the upper low pressure regenerative heating system is adjusted.
PCT/CN2010/071854 2009-08-19 2010-04-16 System for recovering waste heat from flue gas WO2011020334A1 (en)

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