Cochran Boiler: 18 flashcards

It is a **vertical, multi-tubular, fire-tube, internally fired, natural circulation** boiler. It is also a **portable** boiler.

The main shell is a **cylindrical shell** with a **dome-shaped top** (hemispherical crown). It is made of steel plates and is designed to withstand high pressure.

The firebox is the **combustion chamber** where fuel is burned. It is located at the bottom of the shell and is surrounded by water on all sides to absorb maximum heat.

The grate is a **platform** made of cast iron bars, located at the bottom of the firebox. It supports the solid fuel and allows **primary air** to pass through from below for combustion.

The ashpit is a **chamber below the grate** that collects the **ash** and clinker produced during combustion. It also allows air to enter through the grate.

The hot flue gases pass from the firebox into the **flue pipe** (also called the **furnace tube**), which is a large central tube that runs through the water space. From there, gases enter the **smoke box** and then pass through the **fire tubes**.

The fire tubes are **multiple small tubes** that carry hot flue gases through the water. They increase the **heat transfer surface area**, allowing more heat to be absorbed by the water.

The smoke box is a **chamber** located at the top of the boiler that collects the flue gases after they leave the flue pipe. It then distributes them into the fire tubes.

The chimney is a **vertical duct** that expels the exhaust gases to the atmosphere. It creates a **natural draft** that helps draw air into the furnace.

The manhole is an **opening** on the top of the shell that allows **inspection, cleaning, and maintenance** of the boiler's internal parts.

The fusible plug is a **safety device** located at the **top of the firebox**. It contains a low-melting-point alloy that melts if the water level drops too low, releasing steam into the firebox to extinguish the fire and prevent explosion.

The safety valve is a **pressure-relief device** that automatically opens to release steam when the boiler pressure exceeds the safe limit, preventing over-pressurization.

The water level indicator is a **gauge** that shows the current water level inside the boiler. It is essential for ensuring that the water level remains above the firebox and tubes.

The steam stop valve is used to **control the flow of steam** from the boiler to the steam pipe or engine. It can be fully opened or closed to isolate the boiler.

The blow-off cock is a **valve** located at the bottom of the boiler that is used to **discharge sediment, sludge, and impurities** that settle at the bottom. It is also used to drain the boiler for maintenance.

The pressure gauge is an **instrument** that measures the **steam pressure** inside the boiler. It is usually a Bourdon tube gauge and is mounted on the front of the shell.

Fuel is burned on the grate, producing hot flue gases. These gases pass through the flue pipe, smoke box, and fire tubes, transferring heat to the surrounding water. The heated water rises, and cooler water descends, creating **natural circulation**. Steam is collected in the dome and then drawn off through the steam s…

It is compact, has a **vertical design**, and is **self-contained** with all its parts mounted on a single frame. This makes it easy to transport and install at different sites.