Foreword: The development of boilers is divided into two parts: the boiler and the furnace. In the first half of the 18th century, steam engines used in British coal mines, including Watt's initial steam engines, used steam pressure equal to atmospheric pressure. In the second half of the 18th century, steam was used above atmospheric pressure. In the 19th century, the usual steam pressure was increased to about 0.8 MPa. In line with this, Zui's early steam boiler was a large-diameter cylindrical vertical shell with water, and later changed to a horizontal shell to burn in the brick body below the shell.
The development of the boiler is divided into two parts: the boiler and the furnace. In the first half of the 18th century, steam engines used in British coal mines, including Watt's initial steam engines, used steam pressure equal to atmospheric pressure. In the second half of the 18th century, steam was used above atmospheric pressure. In the 19th century, the usual steam pressure was increased to about 0.8 MPa. In line with this, Zui's early steam boiler was a large-diameter cylindrical vertical shell with water, and later changed to a horizontal shell to burn in the brick body below the shell.
As the boiler gets bigger and bigger, in order to increase the heated area, a fire tube is installed in the shell, and the fire is fired at the front end of the fire tube. The flue gas comes out from behind the fire tube, and is discharged to the chimney through the brick flue and heats the outside of the shell. It is called a fire tube boiler. At the beginning, only one fire tube was installed, called a single fire tube boiler or a Connie boiler, which was later added to two fire tubes, called a double fire tube boiler or a Lancashire boiler.
Development history Around 1830, fire tube boilers appeared after mastering the production and expansion technology of high-quality steel pipes. Some fire tubes are placed in the shell to form the main heated surface of the boiler, and fire (smoke) flows through the tubes. Install as many fire pipes as possible below the water storage line of the shell, called a horizontal external combustion tempering tube boiler. Its metal consumption is low, but it requires a lot of masonry.
In the middle of the 19th century, a water tube boiler appeared. The heating surface of the boiler is a water pipe outside the shell, which replaces the fire tube and the fire tube in the shell itself and the shell. The heating area of ​​the boiler and the increase of steam pressure are no longer limited by the diameter of the shell, which is beneficial to increase the boiler evaporation and steam pressure. The cylindrical shell in this type of boiler is nicknamed a drum, or a drum. In the initial water tube boilers, only straight water pipes were used, and the pressure and capacity of the straight water boilers were limited.
At the beginning of the twentieth century, steam turbines began to develop, requiring boilers with higher capacity and steam parameters. Straight water boilers are no longer sufficient. With the development of manufacturing processes and water treatment technologies, curved water tube boilers have emerged. The beginning is a multi-cylinder type. With the application of water wall, superheater and economizer, as well as the improvement of steam and water separation components inside the drum, the number of drums is gradually reduced, which not only saves metal, but also improves the pressure, temperature, capacity and efficiency of the boiler. .
Auxiliary circulation boilers, also known as forced circulation boilers , are developed on the basis of natural circulation boilers. A circulation pump is installed in the downcomer system to enhance the water circulation on the evaporation heating surface. There is no drum in the DC boiler, and the feed water is sent to the economizer by the feed water pump. The water is heated by the water wall and the superheater, and the superheated steam is sent to the steam turbine. The flow resistance of each part is completely overcome by the feed water pump.
After the Second World War, these two types of boilers developed rapidly because the generator set required high temperature and high pressure and large capacity. The purpose of developing these two boilers is to reduce or eliminate the drum, and a small diameter pipe can be used as the heating surface, and the heating surface can be relatively freely arranged. With the advancement of automatic control and water treatment technology, they have matured. At supercritical pressure, the DC boiler is the only type of boiler that can be used. In the 1970s, the large single capacity of the Zui was 27 MPa and the 1300 MW generator set. Later, a composite circulating boiler composed of an auxiliary circulation boiler and a direct current boiler was developed.
During the development of the boiler, the type of fuel has a large impact on the furnace and combustion equipment. Therefore, it is not only required to develop various furnace types to adapt to the combustion characteristics of different fuels, but also to improve combustion efficiency to save energy. In addition, technical improvements in furnaces and combustion equipment also require minimizing pollutants (sulfur oxides and nitrogen oxides) in boiler exhaust. Early boiler shell boilers used fixed grate, multi-combustion with high-quality coal and firewood, coal and The slag is manually operated. After the appearance of the straight water boiler, the mechanized grate was used, and the chain grate was widely used. The air supply under the grate is supplied from the non-segmented “Tongcangfeng†development segment.
The early furnace was low and the combustion efficiency was low. Later, people realized that the volume and structure of the furnace were burning, and the furnace was made high, and the furnace arch and secondary air were used to improve the combustion efficiency.
When the power of the generator set exceeds 6 MW, the size of the grate of these above-mentioned layer burners is too large, the structure is complicated, and it is difficult to arrange. Therefore, in the 1920s, the chamber furnace was used, and the chamber furnace burned pulverized coal and oil. The coal is ground into coal powder by a coal mill and then injected into the furnace with a burner. The capacity of the generator set is no longer limited by the combustion equipment. Since the beginning of the Second World War, almost all of the power plant boilers have used furnaces.
The pulverized coal furnace manufactured in the early years used a U-shaped flame. The pulverized coal gas stream from the burner drops first in the furnace and then turns upward. Later, a swirling burner was placed on the front wall, and the flame formed an L-shaped torch in the furnace. As the boiler capacity increases, the number of swirl burners also begins to increase, either on either side walls or on the front and rear walls. Around 1930, there were DC burners arranged in the four corners of the furnace and mostly in a tangential combustion mode.
After the Second World War, oil was cheap, and many countries began to use oil- fired boilers extensively. The degree of automation of the oil-fired boiler is easy to increase. After the oil price hike in the 1970s, many countries turned to coal resources. At this time, the capacity of the power station boiler is also getting larger and larger, requiring the combustion equipment not only to burn completely, the fire is stable, the operation is reliable, the low load performance is good, and the pollutants in the smoke exhaust must also be reduced.
The development of the boiler is divided into two parts: the boiler and the furnace. In the first half of the 18th century, steam engines used in British coal mines, including Watt's initial steam engines, used steam pressure equal to atmospheric pressure. In the second half of the 18th century, steam was used above atmospheric pressure. In the 19th century, the usual steam pressure was increased to about 0.8 MPa. In line with this, Zui's early steam boiler was a large-diameter cylindrical vertical shell with water, and later changed to a horizontal shell to burn in the brick body below the shell.
As the boiler gets bigger and bigger, in order to increase the heated area, a fire tube is installed in the shell, and the fire is fired at the front end of the fire tube. The flue gas comes out from behind the fire tube, and is discharged to the chimney through the brick flue and heats the outside of the shell. It is called a fire tube boiler. At the beginning, only one fire tube was installed, called a single fire tube boiler or a Connie boiler, which was later added to two fire tubes, called a double fire tube boiler or a Lancashire boiler.
Development history Around 1830, fire tube boilers appeared after mastering the production and expansion technology of high-quality steel pipes. Some fire tubes are placed in the shell to form the main heated surface of the boiler, and fire (smoke) flows through the tubes. Install as many fire pipes as possible below the water storage line of the shell, called a horizontal external combustion tempering tube boiler. Its metal consumption is low, but it requires a lot of masonry.
In the middle of the 19th century, a water tube boiler appeared. The heating surface of the boiler is a water pipe outside the shell, which replaces the fire tube and the fire tube in the shell itself and the shell. The heating area of ​​the boiler and the increase of steam pressure are no longer limited by the diameter of the shell, which is beneficial to increase the boiler evaporation and steam pressure. The cylindrical shell in this type of boiler is nicknamed a drum, or a drum. In the initial water tube boilers, only straight water pipes were used, and the pressure and capacity of the straight water boilers were limited.
At the beginning of the twentieth century, steam turbines began to develop, requiring boilers with higher capacity and steam parameters. Straight water boilers are no longer sufficient. With the development of manufacturing processes and water treatment technologies, curved water tube boilers have emerged. The beginning is a multi-cylinder type. With the application of water wall, superheater and economizer, as well as the improvement of steam and water separation components inside the drum, the number of drums is gradually reduced, which not only saves metal, but also improves the pressure, temperature, capacity and efficiency of the boiler. .
Auxiliary circulation boilers, also known as forced circulation boilers , are developed on the basis of natural circulation boilers. A circulation pump is installed in the downcomer system to enhance the water circulation on the evaporation heating surface. There is no drum in the DC boiler, and the feed water is sent to the economizer by the feed water pump. The water is heated by the water wall and the superheater, and the superheated steam is sent to the steam turbine. The flow resistance of each part is completely overcome by the feed water pump.
After the Second World War, these two types of boilers developed rapidly because the generator set required high temperature and high pressure and large capacity. The purpose of developing these two boilers is to reduce or eliminate the drum, and a small diameter pipe can be used as the heating surface, and the heating surface can be relatively freely arranged. With the advancement of automatic control and water treatment technology, they have matured. At supercritical pressure, the DC boiler is the only type of boiler that can be used. In the 1970s, the large single capacity of the Zui was 27 MPa and the 1300 MW generator set. Later, a composite circulating boiler composed of an auxiliary circulation boiler and a direct current boiler was developed.
During the development of the boiler, the type of fuel has a large impact on the furnace and combustion equipment. Therefore, it is not only required to develop various furnace types to adapt to the combustion characteristics of different fuels, but also to improve combustion efficiency to save energy. In addition, technical improvements in furnaces and combustion equipment also require minimizing pollutants (sulfur oxides and nitrogen oxides) in boiler exhaust. Early boiler shell boilers used fixed grate, multi-combustion with high-quality coal and firewood, coal and The slag is manually operated. After the appearance of the straight water boiler, the mechanized grate was used, and the chain grate was widely used. The air supply under the grate is supplied from the non-segmented “Tongcangfeng†development segment.
The early furnace was low and the combustion efficiency was low. Later, people realized that the volume and structure of the furnace were burning, and the furnace was made high, and the furnace arch and secondary air were used to improve the combustion efficiency.
When the power of the generator set exceeds 6 MW, the size of the grate of these above-mentioned layer burners is too large, the structure is complicated, and it is difficult to arrange. Therefore, in the 1920s, the chamber furnace was used, and the chamber furnace burned pulverized coal and oil. The coal is ground into coal powder by a coal mill and then injected into the furnace with a burner. The capacity of the generator set is no longer limited by the combustion equipment. Since the beginning of the Second World War, almost all of the power plant boilers have used furnaces.
The pulverized coal furnace manufactured in the early years used a U-shaped flame. The pulverized coal gas stream from the burner drops first in the furnace and then turns upward. Later, a swirling burner was placed on the front wall, and the flame formed an L-shaped torch in the furnace. As the boiler capacity increases, the number of swirl burners also begins to increase, either on either side walls or on the front and rear walls. Around 1930, there were DC burners arranged in the four corners of the furnace and mostly in a tangential combustion mode.
After the Second World War, oil was cheap, and many countries began to use oil- fired boilers extensively. The degree of automation of the oil-fired boiler is easy to increase. After the oil price hike in the 1970s, many countries turned to coal resources. At this time, the capacity of the power station boiler is also getting larger and larger, requiring the combustion equipment not only to burn completely, the fire is stable, the operation is reliable, the low load performance is good, and the pollutants in the smoke exhaust must also be reduced.
Plasticizer is widely used in industrial production of polymer materials, also known as plasticizer. Any substance added to a polymer material that increases the plasticity of the polymer is called a plasticizer. Plasticizer can improve the performance of polymer materials, reduce production costs and increase production benefits. [1] is a kind of important additives, chemical products as additives commonly used in plastics, concrete, mortar, the material such as cement, gypsum, cosmetic and detergent, especially in PVC plastic products, in order to increase the plasticity of the plastic and improve the strength of the plastic, you need to add phthalic acid ester, sometimes its content can be up to 50% of the products. Weakened the effect of plasticizer mainly resin molecular valence bond between time, increase the mobility of the resin molecular bonds, reducing resin molecular crystalline, increase the plasticity resin molecules, enhanced the flexibility, easy to machining, can legally used for industrial purposes, widely exists in food packaging, cosmetics, medical equipment, water and environment. Such as plastic wrap, food packaging, toys and so on.
Imported Premium Plasticizer,Good Permeability Plasticizer,Resistant Plasticizer,Food Container Plasticizer
Xingbang High Molecular Materials Co., Ltd. , https://www.chemicaladditive.com