Boiler Types

Steam Boiler

In the first half of the 18th century, steam engines used in British coal mines, including Watt's early steam engines, operated at steam pressures equal to atmospheric pressure. By the latter half of the 18th century, steam pressures above atmospheric pressure were employed. In the 19th century, the common steam pressure reached approximately 0.8 MPa. Correspondingly, the earliest steam boiler was a large-diameter vertical cylindrical shell used for containing water, later replaced by horizontal shells, with fires burning in the brick-lined furnace beneath.

Double Fire Tube Boiler

As boilers grew larger, to increase the heating surface, fire tubes were added to the boiler shell. Fire is burned at the front of the tubes, and the flue gas exits from the back, passing through brick-lined flues to the chimney, thereby heating the outer surface of the boiler shell. This type of boiler is called a fire-tube boiler. Initially, only one fire tube was installed, known as a single fire-tube boiler or Cornish boiler. Later, two fire tubes were added, referred to as a double fire-tube boiler or Lancashire boiler.

Horizontal External Combustion Reheat Tube Boiler

Around 1830, after mastering the production of high-quality steel pipes and expansion technology, fire-tube boilers emerged. Some fire tubes were installed in the boiler shell, forming the main heating surface of the boiler, with the flame (flue gas) flowing through the tubes. A large number of fire tubes were installed below the water line in the boiler shell, known as horizontal external fire-tube boilers. They have a lower metal consumption but require substantial masonry.

Pot drum

In the mid-19th century, the water-tube boiler emerged. The heating surface of the boiler was the water pipes outside the boiler shell, replacing the boiler shell itself and the fire tubes inside. The increased heating surface area and steam pressure of the boiler were no longer limited by the diameter of the boiler shell, which was beneficial for enhancing the boiler's evaporation capacity and steam pressure. The cylindrical boiler shell in such boilers was then renamed to a drum, or commonly referred to as a steam drum. Early water-tube boilers only used straight pipes, which limited both the pressure and capacity of the boilers.

In the early 20th century, the development of steam turbines necessitated larger capacity and higher steam parameter boilers. The straight tube boilers were no longer sufficient. With advancements in manufacturing processes and water treatment technology,弯水管式锅炉 emerged. Initially, multi-drum boilers were used. As water-cooled walls, superheaters, and economizers were adopted, and with improvements to the steam-water separation elements inside the drums, the number of drums gradually decreased, saving metal and also benefiting the boiler's pressure, temperature, capacity, and efficiency.

Safety

Gas boilers differ from other gas appliances in that they have a specific installation location, high gas consumption, and are safety-critical products. Therefore, in North America, all gas fireplace products must pass rigorous safety and environmental standards before being launched into the market. These standards are continuously updated as the products evolve. Different types of fireplace products have specific safety testing standards. For example, the testing standards for balanced flue gas fireplaces and chimney gas fireplaces are different, as are the standards for decorative gas fireplaces and heating gas fireplaces. Consequently, North American balanced flue gas fireplace products should have certifications such as Ansi Z21.88 or CSA2.33, indicating that the product's safety and environmental protection meet the standards, and users can use them with confidence.

Auxiliary Boiler

Historically, fire-tube boilers, water-tube boilers, and firebox boilers were all types of natural circulation boilers. The difference in density is created due to varying heating conditions in the ascending and descending pipes, which causes natural flow. While developing natural circulation boilers, the use of once-through boilers began in the 1930s, and auxiliary circulation boilers were introduced in the 1940s.

Forced circulation boiler

The auxiliary circulating boiler, also known as a forced circulation boiler, is an advancement based on the natural circulation boiler. A circulating pump is added to the downcomer system to enhance the water circulation of the heating surface for evaporation. In a once-through boiler, there is no drum. The feedwater is supplied to the economizer by the feed pump, passes through the water-cooled walls and superheaters, etc., and becomes superheated steam sent to the steam turbine, with all the flow resistance in the various sections being overcome by the feed pump.

Composite circulating boiler

After World War II, both types of boilers experienced rapid development due to the demand for high-temperature, high-pressure, and large-capacity power generation units at the time. The aim of developing these boilers was to minimize or eliminate the use of drum, allowing for the use of small-diameter pipes as heating surfaces and providing greater flexibility in their arrangement. With advancements in automatic control and water treatment technologies, they have become increasingly mature. At supercritical pressure, once-through boilers are the only type that can be used. In the 1970s, the largest single unit capacity was a 27 MPa pressure with a 1300 MW power generation unit. Later, a combined cycle boiler was developed, which was a combination of auxiliary circulation and once-through boilers.

HezeBoilers primarily focus onBoilerR&D and production. Main products: Coal-fired boilers, gas boilers, biomass boilers, and oil-fired boilers. Industries served: Paper mills, dyeing and printing factories, chemical plants, and other industrial steam applications.；Heating and bathing systems for hotels, hospitals, etc.

1 ton of gasHot WaterBoilerHeatingDetails:

Rated thermal power: 0.7 megawatts, heating area:10000 square meters, applicable fuel: natural gas, city gas, liquefied gas, natural gas consumption:75Cubic meters per hour, for detailed parameters of the boiler, pleaseElectricityUnion

1-ton gas boiler features:

The entire unit is equipped with overheat protection (the burner automatically stops and beeps an alarm when the water temperature inside the furnace exceeds a high level), secondary overheat protection (the secondary circuit is automatically disconnected when the boiler shell temperature exceeds 105℃), dry-burn and water shortage protection (the boiler stops working and emits a beep alarm when the water level is below the extremely low level), and electric leakage protection (the power supply is automatically disconnected when the control system detects electrical leakage or a short circuit).

Boilers are designed with atmospheric pressure structure, operating in a pressure-free state, posing no safety risk. They feature advanced multi-layered centrifugal glass wool insulation and are wrapped in high-quality white color steel plates, offering minimal heat loss and aesthetic resistance to rust.