Represents a horizontal internal combustion chamber furnace with a rated thermal power of 12MW, an allowable working pressure of 1.25MPa, and an oil-fired hot water boiler. Boiler model 1, coal-fired, oil-fired, gas-fired, bio-fired boiler Model (1) Model: According to JB/T1626-92 "Industrial Boiler Product Model Preparation Method", the boiler number consists of three parts, each part is connected by a short horizontal line, as shown in the following style: The first part of the model represents the boiler The type of combustion equipment and boiler capacity are divided into three sections. The first section uses two Chinese Pinyin letters to represent the overall type of boiler (see Table 1.2-1, Table 1.2-2); the second section uses one Chinese Pinyin letter to represent the overall type of boiler. Represents combustion equipment (packet table 1.2-3); the third section uses Arabic numerals to indicate the rated evaporation capacity of the steam boiler t/h or the rated thermal power of the hot water boiler MW. The second part of the model’s medium parameters is divided into two sections ( The hot water boiler is divided into three sections), connected by a slash in the middle. The first section indicates the custom steam pressure or the allowable working pressure; the second section indicates the superheated steam temperature (not indicated when the steam temperature is the saturation temperature); the second section of the hot water boiler The first and third sections indicate the outlet water temperature and the inlet water temperature. The third part of the model indicates the fuel type, represented by Chinese pinyin letters, and the Roman letters represent the fuel type classification (see Table 1.2-4) Table 1.2-1 Shell Boiler Overall type code of pot shell boiler Overall type code of pot shell boiler Overall type code of boiler Vertical boiler LS (vertical water) Horizontal external combustion WW (horizontal external) Vertical fire tube LH (vertical fire) Horizontal internal combustion WN (horizontal internal) Note : Horizontal water and fire tube quick-installation boiler overall type code is DN, Table 1.2-2 Water tube boiler overall type code water tube boiler overall type code water tube boiler overall type code single drum vertical DL (single type) double tube boiler horizontal SH ( Double horizontal) single drum vertical type DZ (single type) vertical and horizontal drum type ZH (vertical and horizontal) single drum horizontal type DH (single horizontal) forced circulation type QX (forced) double drum vertical type SZ (double vertical) Table 1.2 -3 Combustion equipment code Combustion equipment code Combustion equipment code Fixed grate G (solid) Coal thrower P (throwing) Fixed double-layer grate C (layer) Vibrating grate Z (vibrating) Movable hand grate H (movable) Lower feeding grate A (lower) chain grate L (chain) boiling furnace F (boiling) reciprocating grate W (forward) chamber furnace S (chamber) Note: pulverized coal furnace and oil and gas boiler are chamber furnaces, olefin burning The equipment code is S. Table 1.2-4 Fuel variety code Fuel variety code Fuel variety code Fuel variety code Class I inferior coal L I class I bituminous coal A I type coal Anthracite WⅠ lignite H sugarcane bagasse GⅢ type anthracite WⅡ lean coal P diesel YC heavy oil YZ coke oven gas QJ oil shale YM natural gas QT liquefied petroleum gas QY other fuels T Note: ① Small oil and gas boilers are generally suitable for a variety of fuels, so the fuel code is usually They are all written as Y or Q② In the boiler model representation method, for normal pressure hot water boilers, only the normal pressure code C must be added before the model code, and the allowable working pressure must be cancelled. The other representation methods remain unchanged. (2) Model examples ( See Table 1.2-5) Table 1.2-5 Model Examples Model Representative Meaning LSS0.2-0.04-Y(Q) represents a vertical water tube chamber burner with a rated evaporation capacity of 0.2t/h, a rated steam pressure of 0.04MPa, and a saturated Temperature, steam boiler whose main fuel is oil (can also be gas). WNS0.7-0.7/95/70-Y represents a horizontal internal combustion chamber furnace, with a rated thermal power of 0.7MW, an allowable working pressure of 0.7MPa, and water outlet A hot water boiler with a temperature of 95°C, a return water temperature of 70°C, and oil as fuel. DZL2-1.25-AⅡ represents a single-drum longitudinal chain grate boiler with a rated evaporation capacity of 2t/h and a rated steam pressure of 1.25MPa. , saturation temperature, steam boiler SHL20-2.5/400-AⅢ with Class II bituminous coal as fuel, represents a double-drum transverse chain grate boiler, rated evaporation capacity is 20t/h, rated
The steam pressure is 2.5 MPa, the superheated steam temperature is 400℃, and the fuel is Class III bituminous coal steam boiler. CLHS0.5-95/70-Y represents a vertical fire tube chamber furnace, the rated thermal power is 0.5MW, and the outlet water temperature is 95℃, return water temperature is 70℃, oil-fired atmospheric pressure hot water boiler. For boilers imported from abroad, the models are different in different countries, and there is no unified regulation. They can be identified based on their product samples, drawings, product quality certificates, etc. 2. , Power station boiler model ② Power station boiler model representation and description The power station boiler model consists of three parts, each part is connected with a short horizontal line. For details, please see the following power station boiler model representation and its description: Part 1, Part 2, Part 3 Design sequence number, outlet steam pressure, evaporation capacity, factory code △△ X X , the first number indicates the evaporation capacity (t/h), and the following number indicates the outlet steam pressure (working pressure). The third part: Boiler design sequence number, such as: DG-120/39-1, indicates that the evaporation capacity is manufactured by Dongfang Boiler Factory A boiler with a capacity of 120t/h and a superheated steam pressure of 3.82Mpa (39kgf/cm2) is designed for the first time. 3. Boiler categories, parameters and models (1) Boilers and their classifications Boilers are also called steam generators, which use fuel Or heat energy from waste heat in industrial production, heat exchange equipment that heats the working medium to a certain temperature and pressure. Boilers are widely used and have many types. They can generally be classified according to the following methods: 1. Classification of power station boilers by use: Most are large-capacity, high-voltage Parametric boilers, fire chamber combustion, high thermal efficiency, the outlet working fluid is superheated steam. Industrial boilers: used for industrial production and heating, mostly low pressure, low temperature, small capacity boilers, mostly fire bed combustion, low thermal efficiency; the outlet working fluid is Those with steam are called steam industrial boilers, and those with hot water as the outlet working fluid are called hot water boilers. Marine boilers: used as ship power, generally use low and medium parameters, mostly fuel oil. Boilers are small in size and light in weight. Locomotive boilers: used For locomotive power, it is generally small capacity, low parameters, fire bed combustion, mainly coal-fired, the boiler has a compact structure, and is now rarely used. Steam injection boiler: used for steam injection thermal recovery of heavy oil in oil fields, exported working fluid Generally, it is high-pressure wet steam. 2. Fire tube boilers are classified according to structure: the flue gas flows through the fire tube and can be made into a small capacity, low parameter boiler with low thermal efficiency, but simple structure, low water quality requirements, and easy operation and maintenance. Water pipe Boiler: Steam and water flow through the tube, which can be made into a small-capacity, low-parameter boiler or a large-capacity, high-parameter boiler. Power station boilers are all water tube boilers with high thermal efficiency, but the requirements for water quality and operation level are also relatively high. High. 3. Classification by circulation method. Natural circulation drum boiler: It has a drum and uses the density difference of the working fluid in the downcomer and the riser tube to generate working fluid circulation. It can only be used below the critical pressure. Multiple forced circulation drum boilers: Also called auxiliary circulation drum boiler. It has a drum and a circulation pump. It uses the density difference of the working fluid in the circulation loop and the pressure of the circulation pump to establish a circulation of the working fluid. It can only be used below the critical pressure. Low-rate circulation boiler: has a steam-water separator And circulation pump, mainly rely on the circulation pump to establish working fluid circulation, which can be applied to subcritical pressure and supercritical pressure. The circulation rate is low, generally 1.25~2.0. DC boiler: no drum, the feed water * water pump pressure, passes through the heating surface once Produces steam and is suitable for high-pressure and supercritical pressure boilers. Compound cycle boiler: It has a recirculation pump. It operates in recirculation mode when the load is low and in DC mode when the load is high. It can be applied to subcritical pressure and supercritical pressure. 4. According to the boiler outlet working fluid pressure, the general pressure of low-pressure boilers is less than 1.275MPa (13kgf/cm2), the general pressure of medium-pressure boilers is 3.825MPa (39kgf/cm2), and the general pressure of high-pressure boilers is 9.8MPa (100kgf/cm2).
) The general pressure of ultra-high pressure boilers is 1.3.73MPa (140kgf/cm2). The general pressure of subcritical pressure boilers is 16.67MPa (170kgf/cm2). The pressure of supercritical pressure boilers is greater than 22.13MPa (225.65kgf/cm2). 5. Classification of fires according to combustion methods Bed combustion boiler: mainly used in industrial boilers, including fixed grate furnaces, inverted grate stoker furnaces, vibrating grate furnaces; bottom-feed grate furnaces and reciprocating feed grate furnaces. The fuel is mainly in the grate Upper combustion. Fire chamber combustion boiler: Mainly used in power station boilers. Boilers that burn liquid fuel, gaseous fuel and pulverized coal are all fire chamber combustion boilers. When the fire chamber burns, the fuel mainly burns in suspension in the furnace space. Cyclone (boiling) Furnace: The air flow rate sent to the grate is high, causing large coal particles to tumble and burn in the boiling bed above the grate. Small coal particles rise with the air and burn. Used to burn inferior fuel. Mostly industrial boilers, large-scale circulation Boiling combustion boilers can be used as power station boilers. 6. Classified according to the fuel or energy used. Solid fuel boilers use solid fuels such as coal. Liquid fuel boilers use liquid fuels such as heavy oil. Gas fuel boilers use gaseous fuels such as natural gas. Waste heat boilers utilize Waste heat from metallurgy, petrochemical and other industries is used as a heat source. Atomic energy boilers use heat energy released by nuclear reactors as steam generators as heat sources. Waste boilers use garbage, bark, waste liquids, etc. as waste boilers. Other energy boilers use geothermal, solar and other energy sources. Steam generator or water heater. 7. Classification according to slagging method. Solid slagging boiler: The ash generated after the fuel is burned is discharged in a solid state, which is the main slagging method of the coal-fired boiler. Liquid slag boiler: The ash generated after the fuel is burned The ash and slag flows out from the slag port in a liquid state, is cracked into small particles in the cooling water of the cracking box, and then discharged into the ditch. 8. Negative pressure boilers are classified according to furnace flue gas pressure. The furnace pressure is maintained at negative pressure, and there are blowers and induced draft fans. The main types of coal boilers. The furnace pressure of micro-positive pressure boilers is greater than 2~5 kPa and does not require an induced draft fan, so it is suitable for low-oxygen combustion. The furnace pressure of supercharged boilers is greater than 0.3 MPa and is used for steam-gas combined cycle. 9. Press Drum layout classification: The number of boiler drums is generally one or two, and the drums can be placed vertically or horizontally. Modern drum-type power station boilers adopt a single drum type, and industrial boilers adopt a single drum or double drum type. 10 , According to the furnace type classification, there are many types of boilers, including inverted U-type, tower type, box type, T-type, U-type, N-type, L-type, D-type, A-type, etc. D-type and A-type are used for industrial boilers. Other furnace types are generally used in power station boilers. 11. Boilers are classified according to the factory type. Boilers can be arranged in open air, semi open air, indoors, underground or in caves. Industrial boilers generally adopt indoor layout, while power station boilers mainly adopt indoor semi open air or open air layout. 12 , according to the factory type classification of boilers, they can be divided into quick-installation boilers, assembled boilers and bulk boilers. Small boilers can adopt the quick-installation type, and power station boilers are generally assembled or bulk-packed.
(2) Boiler equipment composition and its Working process boiler equipment composition: The boiler is composed of a series of equipment, which can be divided into two categories: main components and auxiliary equipment. The main components and functions of large-scale natural circulation high-pressure boilers are as follows: 1. Furnace: ensure that the fuel is burned out and exported The flue gas temperature is cooled to a value where the convection heating surface can work safely; 2. Combustion equipment: Send the fuel and air required for combustion into the furnace to stabilize the fuel ignition and achieve good combustion; 3. Boiler drum: It is the heating surface of the natural circulation boiler The closure connects the heating surfaces of the boiler together and forms a water circulation loop with the water wall, downcomer, etc. The drum stores steam and water and can adapt to load changes. There is a steam-water separation device inside to ensure the quality of steam and water. Once-through boilers do not have a drum. . 4. Water-cooled wall: It is the main radiation heating surface of the boiler. It absorbs the radiant heat of the furnace, heats the working fluid, and protects the furnace wall. The rear water-cooled wall tube is called a slag condensing tube to prevent slagging in the superheater. 5. Superheater : Heating the saturated steam to the rated superheated steam temperature. Steam boilers and hot water boilers that produce saturated steam do not have superheaters. 6. Reheater: Heating the exhaust steam from the high-pressure cylinder of the steam turbine to a higher temperature and then sending it to the medium-pressure cylinder of the steam turbine. Expansion work. Used in large power stations
Boiler to improve the thermal efficiency of the power station. 7. Economizer: Use the heat of the flue gas at the end of the boiler to heat the feed water to reduce the exhaust gas temperature and save fuel. 8. Air preheater: Heat the air for fuel to enhance ignition and combustion; Absorb the waste heat of flue gas, reduce exhaust temperature, and improve boiler efficiency. 9. Furnace wall: It is the protective shell of the boiler, which plays the role of sealing and insulation. The heavy furnace wall in small boilers can also play the role of supporting boiler components. 10. Structure : Support and fix the boiler components and maintain their relative positions. The auxiliary equipment of the boiler and its functions are as follows: (1) Fuel supply equipment stores and transports fuel. (2) Coal grinding and pulverizing equipment grinds coal into pulverized coal and The input combustion equipment of the boiler uses pulverized coal for combustion. (3) The air supply equipment uses an air blower to transport the air heated by the air preheater to the furnace and coal grinding device for use. (4) The induced draft equipment uses an induced draft fan and a chimney to drive the boiler The discharged flue gas is sent to the atmosphere. (5) The water supply equipment uses the water supply pump to send the feed water treated by the water treatment equipment into the boiler. (6) The dust removal and slag removal equipment removes the ash and slag from the boiler and transports it away. (7) Dust removal The equipment removes fly ash in boiler flue gas and improves environmental sanitation. (8) Automatic control equipment includes automatic detection, program control, automatic protection and automatic adjustment. 4. Theoretical basis of boiler combustion (1) Composition of coal: In nature, coal is A mixture of various substances, its main components are carbon, hydrogen, oxygen, nitrogen, sulfur, ash and moisture.
1. Carbon: Represented by the symbol C, it is the main component of coal. The more carbon the coal contains, the higher the calorific value. However, coal with a higher carbon content is more difficult to catch fire because carbon can burn at a relatively high temperature. .Generally, carbon accounts for about 50∽90.2 of the fuel composition. Hydrogen: Represented by the symbol H, it is the most active component in coal. The more content in coal, the easier it is for the fuel to catch fire. The amount of hydrogen in coal is about 2∽5.
3. Sulfur: Represented by the symbol S, it is a harmful element in coal. Sulfur burns to generate sulfur dioxide (SO2) or sulfur trioxide (SO3) gas, which pollutes the atmosphere and is harmful to the human body. These gases condense with water vapor in the flue gas. The water droplets on the heating surface combine to generate sulfurous acid (H2SO3) or sulfuric acid (H2SO4) that corrodes the metal. Not only that, the discharge of sulfur-containing flue gas into the atmosphere will also cause environmental pollution. Coal with high sulfur content is prone to spontaneous combustion. The content of coal in my country is 0.5∽5.
4. Oxygen: represented by the symbol O, it is a non-flammable component. The oxygen content in coal is 1∽10.
5. Nitrogen: Represented by the symbol N, it is a non-flammable component, but it can react with oxygen at high temperatures to form nitrogen oxides (NOx), which is a harmful substance. Under sunlight and ultraviolet rays, it can react with hydrocarbons to form optical oxidants. Cause air pollution.
6. Ash content: Represented by the symbol A, it is the unburnable solid ash in coal and is composed of a variety of compounds. Ash with a low melting temperature is easy to soften and coke, affecting normal combustion. Therefore, more ash content means poor coal quality. Ash in coal The share accounts for about 5∽35.
7. Moisture: represented by the symbol W. Excessive moisture in coal will directly reduce the heat generated by coal combustion and lower the combustion temperature.
2. Calorific value of coal
The heat released when 1Kg of coal is completely burned is called the calorific value of coal.
1. High calorific value (Qgw) refers to the maximum possible calorific value of coal.
2. Low calorific value (Qdw) refers to the actual calorific value of coal under normal combustion conditions.
my country's current boiler combustion equipment is calculated based on the low calorific value of actual coal. There are different types of coal. , the calorific value often differs greatly. When the boiler output remains unchanged, when burning coal with high calorific value, the coal consumption will be small, and when burning coal with low calorific value, the coal consumption will inevitably increase. Therefore, , generally talking about the size of fuel consumption without considering the type of coal, it cannot correctly reflect the economics of boiler equipment operation. In order to correctly assess the economics of boiler equipment operation, Qd is usually
Coal with w=7000Kcal/Kg (approximately 29300KJ/Kg) is defined as standard coal, which facilitates calculation and assessment.
3. Combustion of coal
(1) Conditions for complete coal combustion
1. Appropriate amount of air
2. A certain combustion temperature
3. Mixing uniformity of fuel and air
4. Sufficient combustion time
(2) Coal combustion process
1. Preheating and drying
2. Volatiles evaporate and start to catch fire
3. Fixed carbon ignites and burns
4. Combustion of fixed carbon and formation of ash.