The development of boiler is divided into two aspects: Boiler and furnace:

In the first half of the eighteenth Century, the steam engine used by British coal mines, including Watt's first steam engine, was equal to the atmospheric pressure. In the latter half of the eighteenth Century, steam was used above atmospheric pressure. In nineteenth Century, the steam pressure was increased to about 0.8 mpa. The steam boiler is the first large diameter cylindrical vertical shell and one water, then use horizontal shell, the shell bottom brick fire furnace.

As the boiler is bigger, in order to increase the heating area, installation of fire extinguishers in the shell, the fire in the fire smoke from the fire front, back through the brick row to the chimney flue and external heating of the shell, called fire tube boiler. Only one cylinder, called single drum boiler or Cornish boiler, and later added two fire extinguishers, called double drum boiler or Lancashire boiler.

Around 1830, after mastering the production of high quality steel pipe and tube expansion technology, the fire tube boiler. Some fire pipes are installed in the shell, which forms the main heating surface of the boiler. As far as possible in the shell of the water tank installed on the fire pipe as far as possible, known as horizontal external combustion boiler. Its metal consumption is low, but requires a lot of masonry.

In the middle of the nineteenth Century, there was a water tube boiler. The heating surface of the boiler shell is outside the pipe, replaced the shell itself and the shell in fire extinguishers and fire tube. The increase of heating area and steam pressure of boiler is no longer limited by the shell diameter, which is helpful to improve the boiler evaporation and steam pressure. The cylindrical shell of the boiler is changed into a boiler drum or a drum. In the early stage, only the straight pipe was used in the boiler, and the pressure and capacity of the straight pipe boiler were limited.

At the beginning of the twentieth Century, the turbine began to develop, which required a boiler with high capacity and steam parameters. Straight tube boiler has been unable to meet the requirements. With the development of manufacturing technology and water treatment technology, the bend tube boiler. The beginning is the use of multi drum. With the application of water wall, superheater and economizer, and improve the internal drum steam and water separation device, the number of drum gradually reduced, which saves the metal, and to improve the boiler pressure, temperature, capacity and efficiency.

Before the fire tube boiler, fire tube boiler and water tube boilers are natural circulation boiler, water vapor in the rising and falling in the pipeline for heating, caused by density difference caused by natural flow. In the development of natural circulation boiler, at the same time, from the beginning of 30s, the use of DC boiler, in 40s began to use auxiliary circulation boiler.

The auxiliary circulation boiler is also called the forced circulation boiler, which is developed on the basis of natural circulation boiler. A circulating pump is added in the downcomer system to strengthen the water circulation of the evaporating heating surface. In the direct current boiler, the boiler is not provided with a drum, and the feed water is fed into the coal economizer by the water supply pump, and the superheated surface of the water cooling wall, the superheater and the like is evaporated into the steam turbine.

After the Second World War, these two types of boilers have been developed rapidly, because at that time the generator sets require high temperature, high pressure and large capacity. The purpose of the development of these two kinds of boilers is to reduce or not to use a small diameter tube as heating surface. With the development of automatic control and water treatment technology. In the supercritical pressure, the DC boiler is the only one can be used in 70s, the largest single capacity is 27 MPa pressure with a 1300 MW generating units. Then, the compound circulation boiler which is composed of an auxiliary circulating boiler and a direct current boiler is developed.

In the development process of the boiler, the fuel type has a great influence on the furnace and combustion equipment. Therefore, not only to develop a variety of furnace type to adapt to different fuel combustion characteristics, but also to improve combustion efficiency in order to save energy. In addition, the furnace and combustion equipment technical improvement also requires to minimize the boiler exhaust pollutants (sulfur oxides and nitrogen oxides)

In the early years, the shell boiler was made of fixed grate, which was made of high quality coal and firewood. After the emergence of the straight pipe boiler, mechanized grate was adopted, and the chain grate was widely used. Under the grate, the air supply is not divided into subsection air, which is developed into subsection air supply.

Early furnace low combustion efficiency. Later it was recognized that the role of furnace volume and structure in the combustion, the furnace will be high, and the use of furnace arch and two winds, thereby enhancing the efficiency of combustion.

When the power of the generating set is more than 6 MW, the size of the grate is too large, the structure is complex, and it is not easy to arrange. Therefore, the chamber combustion furnace is started in 20s, and the combustion chamber. The coal is pulverized by the coal mill into the pulverized coal and then sprayed into the combustion chamber with a burner. Since the beginning of the Second World War, almost all of the power plant boiler room combustion furnace.

Early production of pulverized coal stove using a U shaped flame. The pulverized coal air flow in the combustion chamber is first decreased and then turned up. Later, there appeared a vortex burner arranged in front of the wall, and the flame formed a L torch in the furnace. With the increase of the capacity of the boiler, the number of the swirl burner is also increased, which can be arranged on both sides of the wall, and can also be arranged on the front wall and the back wall. In the year of 1930, the direct current burner is arranged in the four corners of the furnace chamber and mostly tangentially fired.

Oil prices after the Second World War