A high-pressure water tube boiler (also known as water-tube or water tube) circulates water in tubes heated externally by a fire. The furnace burns fuel, creating hot gas that boils water in the steam-generating tubes. The heated water/steam mixture is then pumped into the steam drum. Saturated steam is drawn from the top of the drum. Steam passes through tubes in the hot gas path to become superheated in some services. Steam that is heated above the boiling point at a given pressure is known as superheated steam. Due to the fact that superheated steam is a dry gas, it is typically used to operate turbines, since water droplets can severely damage the blades.
Types Of Water Tube Boilers. Three types of watertube boilers exist, each with a different shape. O-Type The steam and water drums are stacked one above the other in this boiler. Water pipes are curved between the drums, forming an O shape. D-Type The water drum sends water to the generating tubes, which are part of the fire box. Water is boiled into steam and rises into the steam drum, then into the steam header. A-Type There are two water drums in this boiler. Using a shared header, the contents of the two water drums are boiled and sent up generating tubes into the steam drum, then to the steam header.
Water Tube Boiler Components – Boiler Shell: This shell is the external cylindrical part of a pressure container. – Steam drum: It is a collection vessel for steam and water. – Mud drum: This is a cylindrical formed space at the base of the water space. It will gather impurities like mud, sediment, and others. – Water walls: It is a tubing arrangement around the furnace to extract heat from fuel to generate steam. – Furnace: An enclosed space provided for the combustion of fuel. – Safety valve: It finds a use for stopping the unnecessary force from the construction of a boiler.
Working Principle of Water Tube Boiler A water tube boiler works by thermal syphoning (circulation of natural water). This type of boiler consists of two drums, namely the steam drum and the lower drum. Below is a diagram of a water tube boiler, which shows how two drums are connected via a riser and a downcomer. First, water is pumped into the steam type drum using a water pump. Whenever the fuel is burned, hot gases are generated that can be supplied into the boiler's shell. Hot gases produced by the fuel will replace heat with water; the water will be transformed into steam. The concentration will automatically increase as the water temperature rises. Water from the steam drum will be fed into the mud drum via the downcomer tube as well as used to heat the water in the mud drum.