前言： Preface：
汽轮机是火电厂的重要设备，通过汽轮机，蒸汽的热能转化为机械能，为发电机发电提供动力。凝汽器是汽轮机的附属设备，在凝汽器里汽轮机排汽转化为凝结水，体积缩小，压力降低，汽轮机进出蒸汽焓差增大，做功能力提高。凝汽器也为系统水汽循环提供了必要条件。凝汽器工作性能的好坏直接影响到系统的热经济性。衡量凝汽器工作性能的指标主要有端差和真空。
Turbine is an important equipment of thermal power plant. Through turbine，thermal energy of steam transforms into mechanical energy， to provide power for generator. Condenser is an accessory of turbine. Inside a condenser, exhaust steam of turbine transforms into condensed water, which reduces its volume and pressure. Then enthalpy difference between turbine inlet and outlet is increased, and working capacity is improved. Condenser also provides necessary condition for water & steam circulation of system. Working performance of condenser directly affects the heat economical efficiency of the system. Main indexes to measure working performance of condenser are terminal temperature difference and vacuum.
凝汽器是一个表面式换热器，在壳程里流动的是汽轮机排汽和凝结水，管程里流动的是冷却水。冷却水吸收蒸汽热量后,蒸汽凝结成水，冷却水温度升高后排出凝汽器。表面式换热器存在换热管结垢的问题，凝汽器也不例外。凝汽器铜管内壁结垢会严重影响换热效果，大大降低系统的热经济性。凝汽器结垢影响主要体现在端差升高和真空降低。在系统来说主要是发电汽耗增加，煤耗增加，经济效益下降。
Condenser is a surface type heat exchanger. What flows inside shell pass is exhaust steam and condensed water of turbine, while cooling water flows inside tube pass. After the heat is absorbed by cooling water, steam is condensed into water. Cooling water is discharged out of condenser after its temperature rise. Surface type heat exchanger has the problem of scaling on heat exchanging tube, so does condenser. Scaling on inner wall of condenser copper tube may seriously influence heat exchanging
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effect, and largely reduce heat economical efficiency of the system. The effect of scaling in condenser is mainly reflected by increase of terminal temperature difference and decrease of vacuum. To the system, major effect is increase of steam rate and coal consumption, and drop of economical efficiency. 水垢的形成： Formation of scale:
汽轮机组运行时必须有大量的冷却水通过凝汽器来冷却汽轮机排汽，循环冷却水的水温在15℃—35℃之间，适宜藻类和微生物繁殖。循环使用中，大量的水分被蒸发，而补充水中又含有杂质和盐类化合物，冷却水的盐类不断浓缩，水中的碳酸氢钙浓度越来越高，游离CO2-却不断挥发，使Ca（HCO3）2分解为CaCO3而析出形成水垢：
Ca（HCO3）2= CaCO3+CO2+H2O
During the operation of turbine unit, there must be large quantities of cooling water, to cool turbine exhaust steam through condenser. Temperature of circulating cooling water is 15℃ to 35℃, which is suitable for reproduction of algae and microorganism. During recycle, much water is evaporated, and make-up water contains impurities and salt compound. So salt in cooling water is constantly concentrated and calcium bicarbonate concentration in water becomes higher, but free CO2 volatilizes constantly, which makes Ca（HCO3）2 decompose into CaCO3. CaCO3 is finally separated out and becomes scale.
Ca（HCO3）2= CaCO3+CO2+H2O
碳酸盐水垢的产生严重影响了金属的传热效果，循环水温又适合藻类和微生物繁殖生长，脱落下的藻类易发生粘垢，致使循环冷却水水质不断恶化。
Formation of carbonate scale seriously influences the heat exchanging effect of metal. What’s more, temperature of circulating water is suitable for the reproduction and growth of algae and microorganism, and the algae falling out is likely to form viscous aggregates, so quality of circulating cooling water deteriorates constantly.
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循环水在凝汽器铜管内流动，吸收大量的热量，保证了汽轮机正常运行。根据流体力学原理，液体在管道内流动分为层流和紊流两种基本现象。层流边层是紧靠管壁的一层，流速很慢，水中的CaCO3和粘垢最易滞留在管内壁上，形成水垢。
Circulating water flows inside copper tube of condenser, absorbing lots of heat, which ensures normal operation of turbine. According the principle of fluid mechanics, flow of fluid inside tubes is divided into two basic types, namely laminar flow and turbulence flow. Boundary layer of laminar flow is close to tube wall, so the flow rate is low. Therefore, CaCO3 and viscous aggregate in water is likely to remain on inner wall of tube, and then becomes scale. 水垢的危害： Harm of scale:
1、 凝汽器铜管内壁形成水垢后，换热效果下降，导致真空下降，能耗上升，严重时要降低
发电负荷或停机清洗。据有关资料介绍，水冷设备换热器中水垢厚度为2.16mm时，传热系数平均下降51%，设备运行效率下降50%，而形成水垢的时间仅25天。如此短的积垢时间和低传热效率，导致凝汽器长期处在低效率中运行。
1. After scale forms on inner wall of condenser copper tube, heat exchanging effect will be reduced; this causes drop of vacuum and rise of energy consumption. In serious conditions, generating load should be reduced or the unit should be shut down for cleaning. According to relevant information, when thickness of scale in heat exchanger of cooling water device reaches 2.16mm, heat transfer coefficient drops 51% in average, and operation efficiency drops 50%. In that case, it needs only 25 days to form scale. Such short period and low heat transfer efficiency makes condenser operate in low efficiency for a long time.
2、增加了冷却循环水系统的水流阻力，降低了冷却水的流量，增加了循环水泵的能耗。
2. It increases flow resistance of cooling circulating water system, reduces flow of cooling water, and increases energy consumption of circulating water pump.
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3、由于水垢的热导率很低，因而急剧降低了凝汽器的传热系数，导致凝汽器真空降低，按照不同汽轮机的试验资料，真空度每降低1%，汽耗增加1～1.5%,当蒸汽流量不变，将降低汽轮机组的出力。据有关资料介绍，水冷设备换热器中水垢厚度为2.16mm时，传热系数平均下降51%，设备运行效率下降50%，而形成水垢的时间仅25天。
3. Due to low thermal conductivity of scale, there is a sharp drop in heat transfer coefficient of condenser, and a decrease in vacuum of condenser. According to testing data of different turbines, once vacuum degree drops 1%, steam rate increases by 1% ~ 1.5%. When steam flow is stable, output of turbine unit will be decreased. According to relevant information, when thickness of scale in heat exchanger of cooling water device reaches 2.16mm, heat transfer coefficient drops 51% in average, and operation efficiency drops 50%. In that case, it needs only 25 days to form scale.
凝汽器结垢对真空度的影响
Effect of scale in condenser on vacuum degree
机组容量(Mw) Unit capacity 100 50 1.2～2.0 0.8～1.2 26.7 ～ 33.3 20.0 ～ 40.0 水垢厚度(mm) Scale thickness 真空降低(kpa) Vacuum drop 真空度降低(%) Vacuum degree drop 3 ～ 5 2 ～ 4 3 ～ 7.5 2 ～ 6 汽耗增加（%） Steam rate increase 注：真空度降低1%，汽耗增加1～1.5%,当蒸汽量不够，降低汽轮机出力1～2% 。
Note: when vacuum degree drops 1%, steam rate increases by 1%~1.5%; when steam volume is in short, turbine output will be decreased by 1% ~ 2%.
4、水垢的附着，特别是粘泥的附着，会在附着物下部发生局部腐蚀甚至破裂和穿孔。水垢的附着凝汽器铜管会导致铜管堵塞，严重影响设备运行。
4. Sticking of scale, especially sticking of slime will cause local corrosion, or even crack and perforation on the lower part of the equipment.
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Scale in copper tube of condenser will cause block in the tube, and seriously influence the operation of equipment.
5、凝汽器铜管的损坏会造成凝汽器的严重泄露，情况严重或处理不当会造成锅炉锅炉水冷壁管的爆破，严重危及锅炉的安全运行。
5. Damage of copper tube of condenser will cause serious leakage of condenser. If the condition is serious or treated improperly, it will cause explosion of boiler water wall tube, and severely endanger safe operation of boiler.
凝汽器铜管更换为螺纹管后，当汽轮机组运行时，无需外加动力，水的流动成为紊流现象，螺纹管改变了管内水的流动状态，强化换热。同时，破坏水垢和粘泥的形成机理，使水垢和粘泥不能在管壁上滞留，排除了结垢的可能。
After copper tubes of condenser are changed into screwed ones, there is no need to add external force during the operation of turbine. Water flow becomes turbulent flow, for screwed tube changes the flow condition of water inside the tube and strengthens heat exchange. In the mean time, it destroys the formation mechanism of scale and slime, and prevents them from remaining on the tube wall, finally ruling out the possibility of scaling.
High temperature zone
Laminar flow layer
Medium zone
temperature
Low temperature zone
Viscous flow layer
Viscous flow
Laminar flow
Heat exchange
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汽轮机凝汽器更换螺纹管
