1. Boiler furnace type
Since the appearance of cylindrical boilers in the late 18th century, with the various needs of production and life and the development of science and technology, boiler products have developed towards multiple series. The form and structure of the boiler are basically developed in two directions: fire tube boiler and water tube boiler.
On the basis of cylindrical boilers, in order to increase the heating area inside the drum, Henan burners first added a fire tube inside the drum and burned fuel in the fire tube (i.e. single fire tube boiler); then the fire tube was increased to two (i.e. double fire tube boiler); then it developed into a boiler composed of a large number of smoke tubes with smaller diameters or a smoke and fire tube combination boiler; later, the combustion chamber of the boiler was moved from the drum to the outside of the drum. The flue gas of these boilers flows through the tube, so they are collectively called fire tube boilers. Due to structural limitations, the diameter of the fire tube boiler drum is large, it is not suitable to increase the steam pressure, the evaporation capacity is also limited, and the steel consumption is large; because the flue gas longitudinally scours the heating surface, the heat transfer effect is poor and the thermal efficiency is low; but because of its simple structure and low water quality requirements, it is still used by small-capacity boilers.
With the increase in the diversity of parameters and capacity of industrial and domestic steam, boilers have begun to develop in the direction of increasing the external heating area of the drum, that is, in the direction of water tube boilers. Water tube boilers do not have a particularly large diameter drum in structure. The elastic curved water pipe replaces the straight smoke pipe, and the metal consumption is greatly reduced; in terms of layout, the flue gas flows horizontally outside the tube, which enhances the heat transfer effect and significantly improves the evaporation capacity and efficiency of the boiler; in addition, the heating surface composed of the water pipe is simply arranged and the water circulation is reasonable; the boiler has a strong adaptability to fuel.
Fire tube boiler
The fire tube boiler has a larger shell, also known as a shell boiler. The shell of the biomass furnace burner is called vertical when it is placed vertically, and horizontally when it is placed horizontally. Bona thermal energy combustion device is called internal combustion when it is installed inside the boiler shell; it is called external combustion when it is installed outside the boiler shell and only the flue gas flows through the inside of the boiler shell. The heating surface of the boiler can be arranged inside the boiler shell, or inside and outside the boiler shell. The heating surface is divided into two types: fire tube type and water tube type.
1. Vertical fire tube boiler
Its longitudinal center line is placed perpendicular to the ground. Because of its simple structure, small footprint, convenient installation and movement, and convenient operation, it is still used in some temporary construction sites and small buildings with low steam pressure. Living and heating occasions. However, due to the small volume, low thermal efficiency and high metal consumption of the internal combustion furnace, it has been gradually eliminated. It is a vertical curved water tube boiler, and its main pressure-bearing components are the boiler shell, furnace, curved water pipe, etc. After the fuel burns on the grate, the furnace and the curved water pipe in the furnace tube area as the radiation heating surface are heated. The flue gas enters the outer tube area from the throat at the upper rear of the furnace, and is divided into two paths, each circling half a circle on the outer wall of the boiler shell, horizontally flushing the curved water pipe in the smoke box outside the boiler shell, and then merging in the smoke box in front of the boiler, and discharged into the atmosphere through the chimney. The exhaust temperature is about 250℃, and the boiler efficiency is about 60%. It is a vertical straight water tube boiler. The combustion chamber is inside the furnace. The coal burns on the honeycomb grate. The generated flue gas enters the straight water tube bundle space between the upper and lower tube plates from the throat above the furnace side. The flue gas swirls around the downcomer in the middle of the tube bundle, horizontally flushes the straight water pipe, and then enters the smoke box, and is discharged into the atmosphere through the chimney. The thermal efficiency of this boiler can reach 70%, its evaporation capacity is 0.5~1t/h, and the steam pressure is 0.7MPa.
2. Horizontal fire tube boiler
(1) External combustion fire tube boiler: This boiler has no fire tubes and is burned outside the drum. The bottom of the drum is radiated by high temperature. When the water quality is poor, it is easy to cause scale accumulation at the bottom of the drum and overheating and deformation. The combustion thermal efficiency is low, and it is rarely produced now.
(2) Internal combustion fire tube boiler: This type of boiler has a simple enclosure structure and a small overall size, which is suitable for overall assembly and delivery. Due to the use of threaded smoke pipes, the heat transfer performance of the boiler body is close to that of a water tube boiler. Biomass boiler burner and this low nitrogen NOx burner shell structure make it easy to solve the sealing problem of the boiler during micro-positive pressure combustion. At present, most medium and small oil and gas boilers adopt the form of horizontal internal combustion fire tube boilers. According to the structural space form of the flue gas return space at the rear of the combustion chamber, horizontal internal combustion fire tube boilers are divided into dry back type and wet back type. This is a schematic diagram of a dry back internal combustion fire tube boiler. The flue gas return space after combustion is surrounded by refractory materials. By opening the rear cover of the boiler, the fire tube and all smoke tubes can be inspected and repaired. Since the tube sheet is directly washed by high-temperature flue gas, the temperature difference between the inside and outside is large, so this part of the refractory material is easy to damage and needs to be replaced regularly. The point is a schematic diagram of a wet back internal combustion fire tube boiler. The high-temperature flue gas return space surrounded by the water jacket, that is, the smoke return chamber, can also heat the boiler, which improves the heat transfer efficiency of the boiler and reduces the heat dissipation loss. Moreover, this structure makes the flue gas tight and suitable for slightly positive pressure combustion. The disadvantage is that the structure of the water jacket smoke return chamber is more complicated, and the combustion chamber and smoke pipe connected to it are more difficult to repair.
The WNS horizontal internal combustion fire tube boiler of the burner manufacturer can burn light diesel, No. 60 heavy oil and natural gas. It consists of a drum, a chassis, a front smoke box, a rear smoke box, a shell and insulation, combustion equipment, steam and water pipelines, auxiliary machines and automatic control systems. The biomass boiler burner adopts a "wet back" structure, and the flue gas is arranged in three returns. The fuel is burned under positive pressure in the furnace, and the high-temperature flue gas turns through the rear smoke box, enters the convection smoke pipe of the second return to the front smoke box, then returns to the convection smoke pipe of the third return, and finally is discharged through the smoke box chimney. This boiler has a compact structure, small size, light weight, fast steam production and reliable operation. The boiler capacity is 0.5-20t/h, and the steam pressure is 0.7-2.5MPa.
In the German three-pass oil or gas boiler, the flue gas flows horizontally to the rear through the flame tube, and then turns twice at the connection where it leaves the boiler smoke pipe. If additional vortex is formed in the chimney, positive pressure combustion is required. Therefore, the thermal power of the heating boiler is significantly improved. This structural form is particularly suitable for boilers with larger power, which has two types of ordinary extraction and positive pressure combustion. Its NOx emission concentration is <80mg/kWh for gas boilers and <120mgkMh for oil boilers.
1. Boiler furnace type
Since the appearance of cylindrical boilers in the late 18th century, with the various needs of production and life and the development of science and technology, boiler products have developed towards multiple series. The form and structure of the boiler are basically developed in two directions: fire tube boiler and water tube boiler.
On the basis of cylindrical boilers, in order to increase the heating area inside the drum, Henan burners first added a fire tube inside the drum and burned fuel in the fire tube (i.e. single fire tube boiler); then the fire tube was increased to two (i.e. double fire tube boiler); then it developed into a boiler composed of a large number of smoke tubes with smaller diameters or a smoke and fire tube combination boiler; later, the combustion chamber of the boiler was moved from the drum to the outside of the drum. The flue gas of these boilers flows through the tube, so they are collectively called fire tube boilers. Due to structural limitations, the diameter of the fire tube boiler drum is large, it is not suitable to increase the steam pressure, the evaporation capacity is also limited, and the steel consumption is large; because the flue gas longitudinally scours the heating surface, the heat transfer effect is poor and the thermal efficiency is low; but because of its simple structure and low water quality requirements, it is still used by small-capacity boilers.
With the increase in the diversity of parameters and capacity of industrial and domestic steam, boilers have begun to develop in the direction of increasing the external heating area of the drum, that is, in the direction of water tube boilers. Water tube boilers do not have a particularly large diameter drum in structure. The elastic curved water pipe replaces the straight smoke pipe, and the metal consumption is greatly reduced; in terms of layout, the flue gas flows horizontally outside the tube, which enhances the heat transfer effect and significantly improves the evaporation capacity and efficiency of the boiler; in addition, the heating surface composed of the water pipe is simply arranged and the water circulation is reasonable; the boiler has a strong adaptability to fuel.
Fire tube boiler
The fire tube boiler has a larger shell, also known as a shell boiler. The shell of the biomass furnace burner is called vertical when it is placed vertically, and horizontally when it is placed horizontally. Bona thermal energy combustion device is called internal combustion when it is installed inside the boiler shell; it is called external combustion when it is installed outside the boiler shell and only the flue gas flows through the inside of the boiler shell. The heating surface of the boiler can be arranged inside the boiler shell, or inside and outside the boiler shell. The heating surface is divided into two types: fire tube type and water tube type.
1. Vertical fire tube boiler
Its longitudinal center line is placed perpendicular to the ground. Because of its simple structure, small footprint, convenient installation and movement, and convenient operation, it is still used in some temporary construction sites and small buildings with low steam pressure. Living and heating occasions. However, due to the small volume, low thermal efficiency and high metal consumption of the internal combustion furnace, it has been gradually eliminated. It is a vertical curved water tube boiler, and its main pressure-bearing components are the boiler shell, furnace, curved water pipe, etc. After the fuel burns on the grate, the furnace and the curved water pipe in the furnace tube area as the radiation heating surface are heated. The flue gas enters the outer tube area from the throat at the upper rear of the furnace, and is divided into two paths, each circling half a circle on the outer wall of the boiler shell, horizontally flushing the curved water pipe in the smoke box outside the boiler shell, and then merging in the smoke box in front of the boiler, and discharged into the atmosphere through the chimney. The exhaust temperature is about 250℃, and the boiler efficiency is about 60%. It is a vertical straight water tube boiler. The combustion chamber is inside the furnace. The coal burns on the honeycomb grate. The generated flue gas enters the straight water tube bundle space between the upper and lower tube plates from the throat above the furnace side. The flue gas swirls around the downcomer in the middle of the tube bundle, horizontally flushes the straight water pipe, and then enters the smoke box, and is discharged into the atmosphere through the chimney. The thermal efficiency of this boiler can reach 70%, its evaporation capacity is 0.5~1t/h, and the steam pressure is 0.7MPa.
2. Horizontal fire tube boiler
(1) External combustion fire tube boiler: This boiler has no fire tubes and is burned outside the drum. The bottom of the drum is radiated by high temperature. When the water quality is poor, it is easy to cause scale accumulation at the bottom of the drum and overheating and deformation. The combustion thermal efficiency is low, and it is rarely produced now.
(2) Internal combustion fire tube boiler: This type of boiler has a simple enclosure structure and a small overall size, which is suitable for overall assembly and delivery. Due to the use of threaded smoke pipes, the heat transfer performance of the boiler body is close to that of a water tube boiler. Biomass boiler burner and this low nitrogen NOx burner shell structure make it easy to solve the sealing problem of the boiler during micro-positive pressure combustion. At present, most medium and small oil and gas boilers adopt the form of horizontal internal combustion fire tube boilers. According to the structural space form of the flue gas return space at the rear of the combustion chamber, horizontal internal combustion fire tube boilers are divided into dry back type and wet back type. This is a schematic diagram of a dry back internal combustion fire tube boiler. The flue gas return space after combustion is surrounded by refractory materials. By opening the rear cover of the boiler, the fire tube and all smoke tubes can be inspected and repaired. Since the tube sheet is directly washed by high-temperature flue gas, the temperature difference between the inside and outside is large, so this part of the refractory material is easy to damage and needs to be replaced regularly. The point is a schematic diagram of a wet back internal combustion fire tube boiler. The high-temperature flue gas return space surrounded by the water jacket, that is, the smoke return chamber, can also heat the boiler, which improves the heat transfer efficiency of the boiler and reduces the heat dissipation loss. Moreover, this structure makes the flue gas tight and suitable for slightly positive pressure combustion. The disadvantage is that the structure of the water jacket smoke return chamber is more complicated, and the combustion chamber and smoke pipe connected to it are more difficult to repair.
The WNS horizontal internal combustion fire tube boiler of the burner manufacturer can burn light diesel, No. 60 heavy oil and natural gas. It consists of a drum, a chassis, a front smoke box, a rear smoke box, a shell and insulation, combustion equipment, steam and water pipelines, auxiliary machines and automatic control systems. The biomass boiler burner adopts a "wet back" structure, and the flue gas is arranged in three returns. The fuel is burned under positive pressure in the furnace, and the high-temperature flue gas turns through the rear smoke box, enters the convection smoke pipe of the second return to the front smoke box, then returns to the convection smoke pipe of the third return, and finally is discharged through the smoke box chimney. This boiler has a compact structure, small size, light weight, fast steam production and reliable operation. The boiler capacity is 0.5-20t/h, and the steam pressure is 0.7-2.5MPa.
In the German three-pass oil or gas boiler, the flue gas flows horizontally to the rear through the flame tube, and then turns twice at the connection where it leaves the boiler smoke pipe. If additional vortex is formed in the chimney, positive pressure combustion is required. Therefore, the thermal power of the heating boiler is significantly improved. This structural form is particularly suitable for boilers with larger power, which has two types of ordinary extraction and positive pressure combustion. Its NOx emission concentration is <80mg/kWh for gas boilers and <120mgkMh for oil boilers.