跟读练习: How does a Thermal power plant work? - 通过视频学习英语口语
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Thermal power plants help meet almost half of the world's power demand.
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They use water as the working fluid.
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Today's thermal power plants are capable to run under great efficiency by conforming to stringent environmental standards.
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In this video, we will see how a coal -based thermal power plant achieves this in a detailed step -by -step manner.
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By turning the shaft of this generator, we will be able to generate electricity.
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The generator derives motion from a steam turbine, the heart of the power plant.
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In order to turn the steam turbine, you have to supply a high -pressure and high -temperature steam at the inlet of the turbine.
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As the turbine absorbs energy from the high -energy fluid, its pressure and temperature drop toward the outlet.
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You can take a closer look at the uniquely shaped steam turbine rotor blades.
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High -capacity power plants often use different stages of steam turbines, such as high -pressure turbine,
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intermediate -pressure turbine, and low -pressure turbines.
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So, now we have met our objective.
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We have produced electricity from the generator.
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If we can bring the low pressure and low temperature steam back to their original states, which were of a much higher pressure and temperature, we can repeat the process.
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The first step is to raise the pressure.
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You can use a compressor for this purpose.
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But compressing steam is a highly energy intensive process, and such a power plant will not be efficient at all.
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The easy way is to convert the steam into liquid and boost the pressure.
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For this purpose, we'll introduce condenser heat exchangers which sit beneath the low pressure turbine.
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In the condenser, a stream of cold water flows through the tubes.
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The steam rejects heat to this liquid stream and becomes condensed.
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Now we can use a pump to increase the pressure of this feed water.
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Typically, multistage centrifugal pumping is used for this purpose.
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That way, the pressure will revert to its original state.
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The next task is to bring the temperature back to its original value.
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For this purpose, heat is added to the exit of the pump with the help of a boiler.
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High -capacity power plants generally use a type of boiler called a water tube boiler.
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Pulverized coal is then burned inside the boiler.
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The incoming water initially passes through an economizer session.
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Here, the water will capture energy from the flue gas.
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The water flows through a downcomer, and then through water walls, where it transforms into steam.
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The pure steam is separated at a steam drum.
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Now, the working fluid is back to its original state, high pressure and high temperature.
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This steam can be fed back into the steam turbine,
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and the cycle can be repeated over and over again for continuous power production.
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But a power plant working on this basic Rankin cycle will have a very low efficiency and a low capacity.
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We can increase the performance of the power plant considerably with the help of a few simple techniques.
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In case of superheating, even after the liquid has been converted into steam, even more heat is added.
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And with that, the steam becomes superheated.
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The higher the temperature of the steam, the more efficient the cycle.
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Just remember the Carnot's theorem of maximal thermal efficiency possible.
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But the steam turbine material will not withstand temperatures of more than 600 degrees Celsius, so superheating is limited to that threshold.
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The temperature of the steam decreases as it flows along the rows of the blade.
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Consequently, a great way to increase the efficiency of the power plant is to add more heat after the first turbine stage.
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This is known as reheating and it will increase the temperature of the steam again, leading to a high power output and greater efficiency.
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The low pressure sides of the power plant are prone to suck the atmospheric air even with sophisticated sealing arrangements.
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The dissolved gases in the feed water will spoil the boiler material over time.
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To remove these dissolved gases an open feed water heater is introduced
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Hot steam from the turbine is mixed into the feed water steam bubbles so generated will absorb the dissolved gases
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The mixing also preheats the feed water which helps improve the efficiency of the power plant to an even greater extent
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All these techniques make the modern power plant work under an efficiency range of 40 to 45 percent
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Now we'll take a look at how heat addition and heat rejection are executed in an actual power plant.
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The cold liquid is supplied at the condenser with the help of a cooling tower.
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The heated up water from the condenser outlet is sprayed in the cooling tower, which induces a natural air draft and the sprayed water loses heat.
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This is how a colder liquid is always provided at the condenser inlet.
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At the heat addition side, the burning coal produces many pollutants.
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We cannot release these pollutants directly into the atmosphere, so before transferring them to a stack, the exhaust gas is cleaned in an electrostatic precipitator.
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The ESP uses plates with high voltage static electricity to absorb the pollutant particles.
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We hope that we've given you new insights into the inner workings of thermal power plants.
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本课的词汇与口语要点
这节 C1 级别的口语课以视频“How does a Thermal power plant work?”为素材。 视频中反复出现的词有：steam, plant, turbine, pressure, temperature。 这段视频共有 59 个句子、876 个单词可供跟读。 讲话部分时长为 6:58。 说话人语速平稳，每分钟约 126 个词，很适合跟读。 只有 77% 的单词属于英语最常用的 3,000 词，词汇难度较高。
视频中的重点词汇
视频中最难的 15 个单词，附发音和释义：
| 单词 | 发音 | 释义 |
|---|---|---|
| turbine 名词 | /ˈtɜː.baɪn/ | 渦輪機 /涡轮机, 輪機 /轮机 |
| condenser 名词 | /ˈkʰəndɛnsɚ/ | 冷凝器, 凝結器 /凝结器 |
| boiler 名词 | /ˈbɔɪlɚ/ | 鍋爐 /锅炉 |
| dissolve 动词 | /dɪˈzɑlv/ | 解散 |
| pollutant 名词 | /pəˈl(j)uːtənt/ | 污染物 |
| absorb 动词 | /æbˈsɔɹb/ | 吸收 |
| generator 名词 | /ˈdʒɛnəɹeɪtə(ɹ)/ | 發電機 /发电机 |
| outlet 名词 | /ˈaʊtlɛt/ | 出口 |
| compress 动词 | /ˈkɑmpɹɛs/ | 壓縮 /压缩 |
| preheat 动词 | /pɹiːˈhiːt/ | 預熱 /预热 |
| reheat 动词 | /ɹiːˈhiːt/ | 熱 /热, 加熱 /加热 |
| conform 动词 | /kənˈfɔɹm/ | 遵从 |
| heater 名词 | /ˈhitɚ/ | 加熱器 /加热器, 暖氣 /暖气 |
| withstand 动词 | /wɪðˈstænd/ | 抵抗, 反抗 |
| theorem 名词 | /ˈθiərəm/ | 定理 |
视频中出现的短语动词
| 单词 | 释义 |
|---|---|
| heat up 动词 | 加熱 /加热 |
视频中的语法
说话人最常用的结构，并附上视频中的原话：
| 结构 | 视频中的用法 |
|---|---|
| 被动语态 be + 过去分词 — 强调发生了什么，而不是谁做的 | is added · is separated · can be fed |
| 现在完成时 have/has + 过去分词 — 过去发生但与现在仍有关联的事 | have met · have produced · has been converted |
需要注意的发音
说话人用了 3 次缩略和弱读形式，例如 we'll, we've。请按听到的简短形式来说。
- “th” 音: thermal /ˈθɜːməl/, withstand /wɪðˈstænd/, theorem /ˈθiərəm/, threshold /ˈθɹɛʃ(h)oʊld/
- “sh” 和 “zh” 音: shaft /ˈʃɑːft/, rejection /ɹɪˈd͡ʒɛkʃən/, threshold /ˈθɹɛʃ(h)oʊld/
- 长单词——注意重音位置: generator /ˈdʒɛnəɹeɪtə(ɹ)/, precipitator /pɹɪˈsɪpɪˌteɪtə(ɹ)/, atmospheric /ˌætməsˈfɛɹɪk/, consequently /ˈkɑnsɪˌkwɛntli/, considerably /kənˈsɪdəɹəbli/
中文母语者容易读错的音：
- /v/ — 不要读成 /w/，上齿轻触下唇: dissolve /dɪˈzɑlv/, revert /ɹɪˈvɝt/, derive /dɪˈɹaɪv/, voltage /ˈvəʊltɪd͡ʒ/, intensive /ɪnˈtɛnsɪv/
- 词尾辅音 — 要读清楚，后面不要加元音: dissolve /dɪˈzɑlv/, pollutant /pəˈl(j)uːtənt/, absorb /æbˈsɔɹb/, inlet /ˈɪnlət/, outlet /ˈaʊtlɛt/
- /r/ 和 /l/ 的区别: centrifugal /sɛnˈtɹɪf.(j)ə.ɡl̩/, particle /ˈpɑɹtək(ə)l/, considerably /kənˈsɪdəɹəbli/, threshold /ˈθɹɛʃ(h)oʊld/
如何用这段视频练习
- 先完整听一遍视频，不要开口，记下不认识的单词。
- 用正常速度逐句跟读，每句重复到你的节奏与说话人一致为止。
- 录下自己的声音并与原声对比，特别注意 turbine, condenser, boiler 这类单词。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。