In this video, we will learn about the operation and construction of a typical power plant boiler.

在本視頻中，我們將瞭解典型發電廠鍋爐的運行和構造。

We will also clarify a popular misconception associated with boiler operation near the end of the video.

我們還將在視頻結尾處澄清一個與鍋爐運行有關的流行誤解。

The function of the boiler is to convert energy contained in the coal into high temperature steam.

鍋爐的功能是將煤炭中蘊含的能量轉化為高溫蒸汽。

Large power plants typically use a type of boiler called a water tube boiler, where water flows through the tubes and fire surrounds it.

大型發電廠通常使用一種名為水管鍋爐的鍋爐，在這種鍋爐中，水流通過水管，而火則環繞在水管周圍。

Water tube boilers are ideal for high pressure applications.

水管鍋爐是高壓應用的理想選擇。

There are also fire tube boilers, but they are used for small scale applications.

也有火管鍋爐，但都用於小規模應用。

Burners in the boiler convert chemical energy in the pulverized coal into thermal energy.

鍋爐中的燃燒器將煤粉中的化學能轉化為熱能。

The hot gas that is produced travels all over the boiler.

產生的熱氣在鍋爐內四處流動。

The first heat absorption unit of the boiler is an economizer.

鍋爐的第一個吸熱裝置是省煤器。

Highly pressurized water supplied by the feed water pump enters here.

由給水泵提供的高壓水從這裡進入。

The economizer absorbs energy from the flue gas, which raises the temperature of the liquid.

省煤器從煙氣中吸收能量，從而提高液體的溫度。

From there, the water flows into a steam drum to the downcomer.

水從這裡流入蒸汽鼓，再流向導流筒。

It then passes through a narrow tube section called a water wall.

然後，水流通過一個稱為水牆的狹窄管段。

The phase change of the water happens in the water wall.

水的相變發生在水壁中。

The steam that is produced, in addition to some water droplets, enters the steam drum again.

產生的蒸汽和一些水滴再次進入蒸汽鼓。

The real function of the steam drum is to separate the water droplets from the steam.

蒸汽鼓的真正功能是將水滴從蒸汽中分離出來。

As a result, the steam leaving the steam drum is saturated and pure.

是以，離開蒸汽鼓的蒸汽是飽和純淨的。

Now, here are some thermodynamics facts.

下面是一些熱力學知識。

According to the second law of thermodynamics, the greater the temperature of the heat source, the more efficient the cycle.

根據熱力學第二定律，熱源溫度越高，循環效率越高。

Therefore, making the steam temperature very high will result in a highly efficient power plant.

是以，將蒸汽溫度調得很高，就能產生高效發電廠。

But this temperature increase has certain limitations.

但這種溫度上升有一定的侷限性。

The steam turbine blade material cannot withstand temperatures greater than 600 degrees Celsius.

蒸汽輪機葉片材料無法承受 600 攝氏度以上的高溫。

So, one more heat exchanger is added after the steam drum to superheat the steam, and it is heated to the maximum allowable limit.

是以，在蒸汽鼓之後又增加了一個熱交換器來過熱蒸汽，並將其加熱到最大允許極限。

Superheating also reduces the moisture content in the steam.

過熱還能降低蒸汽中的水分含量。

The steam is then supplied to the turbine inlet.

蒸汽隨後被輸送到渦輪機入口。

After the first turbine stage, the temperature drops.

第一級渦輪之後，溫度下降。

A clever idea to increase the power plant efficiency is to bypass the steam completely after the first stage and add more heat.

要提高發電廠的效率，一個聰明的辦法是在第一階段之後完全繞過蒸汽，增加熱量。

This process is known as reheating.

這一過程被稱為再加熱。

A heat exchanger known as a reheater is used for this purpose.

為此，需要使用一種被稱為再熱器的熱交換器。

Reheating and superheating also increase the power plant capacity along with the efficiency.

再加熱和過熱還能提高發電廠的發電量和效率。

Now, let's discuss an important misconception about boilers.

現在，讓我們來討論一下關於鍋爐的一個重要誤解。

We know that the temperature rises across the boiler, but what about pressure?

我們知道整個鍋爐的溫度會升高，但壓力呢？

Consider this droplet of water.

請看這滴水珠。

Assume it is surrounded by a cover.

假設它周圍有一個蓋子。

If it gets converted to steam, obviously the pressure will rise.

如果轉化為蒸汽，壓力顯然會升高。

Now consider the same droplet with no cover.

現在考慮一下沒有覆蓋物的相同液滴。

Here, if the liquid gets converted to steam, the pressure will remain the same.

在這裡，如果液體轉化為蒸汽，壓力將保持不變。

Because the fluid does not have a fixed volume here, it is free to expand.

由於流體在這裡沒有固定的體積，是以可以自由膨脹。

Water inside the boiler is also like the water droplet, without a cover.

鍋爐內的水也像水滴一樣，沒有蓋子。

It's an open-flowing system.

這是一個開放式流動系統。

The water is free to expand when the liquid is converted into steam, which means that the pressure should remain the same throughout an ideal boiler.

當液體轉化為蒸汽時，水可以自由膨脹，這意味著整個理想鍋爐的壓力應保持不變。

In actual practice, due to friction and other irregularities, a small drop in pressure occurs across the boiler.

在實際操作中，由於摩擦和其他不規則因素，整個鍋爐的壓力會略有下降。

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拯救學習工程學，使其免於滅絕。

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請查看我們的 Patreon 頁面，讓我們的教育服務能夠持續下去。

Thank you!

謝謝！