Waste incineration waste heat boiler system

Abstract

According to the waste incineration waste heat boiler system, through the structural design of the waste incineration waste heat boiler system, flue gas of a waste heat boiler can be effectively utilized to heat primary air, it is guaranteed that the temperature of mixed primary air is above the acid dew point temperature, and the temperature of the mixed primary air is increased; the problem of low-temperature corrosion caused by heating primary air through waste heat boiler flue gas in the prior art is solved. Meanwhile, the steam extraction amount needed by heating the primary air through steam extraction of a boiler or a steam turbine in the prior art is saved, the power generation amount or the external steam supply amount is increased through the saved steam extraction amount, the recycling rate of waste incineration treatment is increased, meanwhile, the manufacturing cost of the air preheater for heating the primary air through steam and the occupied space of equipment are reduced, and the energy consumption is reduced. And the flowing resistance of air is reduced. While effective and stable combustion of the garbage is guaranteed, creation of a local reducing atmosphere in the garbage incineration process is facilitated, control over generation of nitric oxide in the combustion process is achieved, and the cost for removing the nitric oxide from the flue gas is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of energy and environmental protection, in particular to a waste incineration waste heat boiler system. Background Art

[0002] With the development of society, more and more garbage is generated, such as domestic garbage, construction waste, etc. Garbage disposal methods include landfill and incineration. The traditional landfill method can no longer cope with the challenge of the surge in the amount of urban garbage brought about by China's urbanization and industrialization. To solve this problem, China has rapidly promoted the application of garbage incineration and waste heat power generation projects as an alternative. This treatment method has the significant advantages of harmlessness, reduction and resource utilization. Through high-temperature incineration, garbage can be effectively treated, thereby reducing pollution to the environment. In addition, incineration can also convert garbage into energy, such as power generation or heating, to achieve resource reuse, which helps reduce dependence on traditional energy.

[0003] However, unlike traditional fossil fuels such as coal, oil and gas, the composition of urban domestic waste is complex, and the combustion products of waste incineration contain a large amount of corrosive acidic gases, high water vapor content, high NOx content, and high oxygen concentration in the flue gas.

[0004] The flue gas characteristics of waste incineration result in the heating surface layout of flue gas heat utilization being different from that of traditional fossil fuel boilers. All coal-fired power station boilers have air preheaters arranged after the economizer in the tail flue. After the flue gas enters the economizer, it releases heat to the boiler feed water through the economizer heating surface tube and reduces the temperature. After that, the flue gas enters the air preheater. After the air preheater heating surface tube releases heat to the air, the flue gas temperature is reduced to about 120°C. Most of the waste heat resources of the flue gas are utilized by the economizer and air preheater.

[0005] However, for waste incineration waste heat boilers, in order to avoid the condensation of acidic gases in the flue gas on the low-temperature heating surface and cause low-temperature corrosion, the last-stage heating surface of the tail flue of the waste heat boiler is only equipped with an economizer, and no air preheater is arranged. The inlet water temperature of the economizer is generally 130℃, which is much higher than the normal air temperature at the inlet of the air preheater, and there must be a certain temperature difference in the heat exchange between the flue gas and the hot water in the economizer, so the exhaust temperature at the economizer outlet is much higher than the exhaust temperature at the outlet of the air preheater of the coal-fired power plant, which is generally between 190℃-250℃, resulting in the exhaust heat loss of the waste incineration waste heat boiler being much higher than that of the coal-fired power plant boiler.

[0006] Since the air coefficient of the waste incineration process is generally higher than that of coal-fired power plant boilers, the exhaust volume generated by waste incineration and the exhaust heat loss of the waste heat boiler are further increased. Due to the high moisture content and low calorific value of garbage, in order to achieve stable combustion of garbage, it is necessary to increase the primary air temperature of garbage incineration. Since the air preheater cannot be arranged in the tail flue, the waste heat boiler for garbage incineration usually uses the extraction steam of the boiler drum and the first stage extraction steam of the turbine as the heat source for heating the primary air to heat the primary air to above 200°C. This primary air heating method consumes precious steam resources and reduces the power generation or external heat supply of the waste combustion power plant. The existing waste incineration system uses an air preheater as a heat exchange device for heating the primary air with steam. Heating the normal temperature primary air to the set temperature value requires a large heat exchange area, which not only increases the floor space, but also requires a large initial investment; in addition, the primary air needs to overcome a large resistance when passing through the air preheater, which increases the power consumption and operation and maintenance costs of the primary air fan.

[0007] In addition, compared with coal-fired boilers, the air coefficient of the garbage incineration process is larger, and the nitrogen content of garbage is generally higher than that of coal, resulting in a high NOx concentration in the flue gas generated by garbage incineration, bringing more environmental protection treatment problems.

[0008] All of the above are problems that are difficult to solve with existing waste incineration systems. Utility Model Content

[0009] In order to solve the problem mentioned in the above background technology that the last-stage heating surface of the tail flue of the existing waste incineration waste heat boiler is only arranged with an economizer, but no longer arranged with an air preheater, the utility model provides a waste incineration waste heat boiler system, including a primary air duct, a circulating flue, a waste heat boiler flue and a combustion chamber;

[0010] The inlet of the circulating flue is connected to the low-temperature circulating flue, and the low-temperature circulating flue is connected to the flue of the waste heat boiler; the inlet of the circulating flue is also connected to the high-temperature circulating flue, and the high-temperature circulating flue is connected to the flue of the waste heat boiler;

[0011] The inlet of the primary air duct is connected to the primary fan; the primary air duct is also connected to an air preheater;

[0012] The inlet of the steam-water side of the air preheater is also connected to the air preheater steam pipeline for heating, and the outlet is connected to the air preheater drain pipeline; the air preheater steam pipeline is connected to the steam drum through a saturated steam outlet pipe;

[0013] The outlet of the primary air duct is connected to the outlet of the circulating flue and merges into a mixed primary air duct, and the mixed primary air duct is connected to the wind chamber at the bottom of the combustion chamber;

[0014] The flue inlet of the waste heat boiler is connected with the flue gas outlet of the combustion chamber; an evaporator, a superheater and an economizer are arranged in the flue of the waste heat boiler, and an economizer is arranged in the last section of the flue gas flowing in the flue of the waste heat boiler; a flue outlet is arranged in the flue of the waste heat boiler; the evaporator is connected with the steam drum through a steam-water circulation pipe; the superheater inlet is connected with the superheated steam pipeline, and the superheated steam pipeline is connected with the steam drum through a saturated steam outlet pipe; the outlet of the economizer is connected with the steam drum through a water supply pipe.

[0015] On the basis of the above technical solution, further, a primary air flow meter is arranged in the primary air duct, a primary air thermometer is arranged in the primary air duct at the outlet of the air preheater; and a superheated steam flow meter is arranged in the inlet pipe of the superheater.

[0016] On the basis of the above technical solution, further, the oxygen concentration range in the mixed primary air duct is 15% to 18%, and the temperature range in the mixed primary air duct is 130°C to 210°C.

[0017] On the basis of the above technical solution, a second circulating flue is further provided, so the second circulating flue is provided on the circulating flue and connected to the combustion chamber through a circulating air port provided on the upper part of the grate, and a circulating flue baffle 2 is provided on the second circulating flue.

[0018] On the basis of the above technical solution, further, a heating steam regulating valve and a heating steam flow meter are provided on the air preheater steam pipeline.

[0019] On the basis of the above technical solution, further, a mixed primary air thermometer is provided on the mixed primary air duct;

[0020] A flue gas circulation fan and a dust collector are arranged on the circulating flue, and a circulating flue gas thermometer and a circulating flue baffle are arranged on the connecting pipe between the flue gas circulation fan outlet and the mixed primary air duct.

[0021] On the basis of the above technical solution, further, the low-temperature circulation flue is provided with a low-temperature circulation flue gas flowmeter and a low-temperature circulation flue duct baffle, and a low-temperature flue gas thermometer is provided at the connection port between the low-temperature circulation flue and the waste heat boiler flue at the rear side of the economizer;

[0022] The high-temperature circulation flue is provided with a high-temperature circulation flue gas flowmeter and a high-temperature circulation flue duct baffle, and a high-temperature flue gas thermometer is provided at the connection port between the high-temperature circulation flue and the waste heat boiler flue, which is located in front of the economizer.

[0023] The waste incineration waste heat boiler system provided by the utility model has the following beneficial effects:

[0024] Through the structural design of the waste incineration waste heat boiler system of the utility model, part of the flue gas is extracted as the heat source of the primary air, and the primary air is heated by a mixed heating method, thereby solving the problems existing in the prior art using an air preheater: if the air preheater is used as a heat exchange device that uses steam to heat the primary air, it will cause low-temperature corrosion of the heated surface; if a larger heat exchange area is required to heat the normal temperature primary air to the set temperature value, the volume of the air preheater will be increased, which not only increases the floor space but also requires greater costs.

[0025] In the preferred technical solution, the waste incineration waste heat boiler system of the utility model can also extract two flue gases with different temperatures and mix them with the primary air through the structural layout, while achieving the control of the temperature target and oxygen concentration target of the mixed primary air, preventing the low-temperature corrosion of the mixed primary air duct, wind chamber and grate, controlling the optimal mixed primary air oxygen concentration, effectively reducing the generation control of nitrogen oxides in the combustion process of waste incineration, and reducing the control cost of nitrogen oxides and the risk of excessive emissions.

[0026] Other technical effects of the technical solution provided by the utility model will be further explained in conjunction with the embodiments of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural schematic diagram of the waste incineration waste heat boiler system.

[0028] Reference numerals:

[0029]

[0030] DETAILED DESCRIPTION

[0031] The utility model provides an embodiment of a waste incineration waste heat boiler system, such as Figure 1As shown, it includes a primary air duct 100, a circulating flue 200, a waste heat boiler flue 300 and a combustion chamber 400; the inlet of the circulating flue 200 is connected to the low-temperature circulating flue 232, and the low-temperature circulating flue 232 is connected to the waste heat boiler flue 300; the inlet of the circulating flue 200 is also connected to the high-temperature circulating flue 242, and the high-temperature circulating flue 242 is connected to the waste heat boiler flue 300; the inlet of the primary air duct 100 is connected to the primary fan 140; the primary air duct 100 is also connected to an air preheater 150; the inlet of the steam-water side of the air preheater 150 is also connected to the air preheater steam pipe 160 for heating, and the outlet is connected to the air preheater drain pipe 130; the air preheater steam pipe 160 is connected to the steam drum 320 through the saturated steam outlet pipe 333; the outlet of the primary air duct 100 is connected to the The outlet of the circulating flue 200 is connected and merged into the mixed primary air duct 450, and the mixed primary air duct 450 is connected to the wind chamber 440 at the lower part of the combustion chamber 400; the inlet of the waste heat boiler flue 300 is connected to the flue gas outlet of the combustion chamber 400; an evaporator 310, a superheater 330 and an economizer 340 are arranged in the waste heat boiler flue 300, and the economizer 340 is arranged in the last section of the flue gas flow in the waste heat boiler flue 300; the waste heat boiler flue 300 is provided with a flue outlet 350; the evaporator 310 is connected to the steam drum 320 through a steam-water circulation pipe 315; the inlet of the superheater 330 is connected to the superheated steam pipe 336, and the superheated steam pipe 336 is connected to the steam drum 320 through a saturated steam outlet pipe 333; the outlet of the economizer 340 is connected to the steam drum 320 through a water supply pipe 341.

[0032] Preferably, a primary air flow meter 110 is provided in the primary air duct 100 , and a primary air thermometer 105 is provided in the primary air duct 100 at the outlet of the air preheater 150 ; and a superheated steam flow meter 338 is provided in the inlet pipe of the superheater 330 .

[0033] Preferably, the oxygen concentration in the mixed primary air duct 450 is in the range of 15% to 18%, and the temperature in the mixed primary air duct 450 is in the range of 130°C to 210°C.

[0034] In the preferred embodiment, a second circulating flue 413 is further provided, so the second circulating flue 413 is provided on the circulating flue 200 and connected to the combustion chamber 400 through a circulating air port 417 provided on the upper part of the grate 420, and a circulating flue baffle 2 415 is provided on the second circulating flue 413. The flue gas circulating through the second circulating flue 413 can also enter the combustion chamber 400 from the circulating air port 417 above the combustion chamber 400.

[0035] Preferably, a heating steam regulating valve 170 and a heating steam flow meter 180 are provided on the air preheater steam pipeline 160 .

[0036] Furthermore, a mixed primary air thermometer 460 is provided on the mixed primary air duct 450;

[0037] The circulating flue 200 is provided with a flue gas circulating fan 210 and a dust collector 220, and a circulating flue gas thermometer 203 and a circulating flue baffle 206 are provided on the connecting pipe between the outlet of the flue gas circulating fan 210 and the mixed primary air duct 450.

[0038] Preferably, the low-temperature circulation flue 232 is provided with a low-temperature circulation flue gas flowmeter 231 and a low-temperature circulation flue duct baffle 233, and the connection port between the low-temperature circulation flue 232 and the waste heat boiler flue 300 is located at the rear side of the economizer 340, where a low-temperature flue gas thermometer 234 is provided;

[0039] The high-temperature circulation flue 242 is provided with a high-temperature circulation flue gas flowmeter 241 and a high-temperature circulation flue duct baffle 243. A high-temperature flue gas thermometer 244 is provided at the connection port between the high-temperature circulation flue 242 and the waste heat boiler flue 300, which is located in front of the economizer 340.

[0040] Preferably, a flue gas circulation system purge door 120 is further provided between the primary air duct 100 and the circulating flue duct 200 .

[0041] Preferably, an online flue gas analysis system 355 is also provided at the end of the waste heat boiler flue 300 .

[0042] Other optional structures in the embodiment of the waste incineration waste heat boiler system of the utility model are as follows Figure 1 As shown, in addition, those skilled in the art can also add other optional instruments or equipment based on the innovative technical solution of the utility model.

[0043] Combination Figure 1 The working process of the waste incineration waste heat boiler system provided by the utility model is as follows:

[0044] Domestic garbage from the garbage pool enters the grate 420 at the bottom of the combustion chamber 400 through the garbage feeder 430. The hot flue gas from the circulating flue 200 is mixed with the primary air from the primary air duct 100 in the mixed primary air duct, and the primary air is mixed and heated. The heated mixed primary air enters the combustion chamber 400 from the bottom of the grate 420 through the wind chamber 440, and is incompletely burned with the garbage on the top of the grate, creating a local reducing atmosphere, so that the nitrogen element in the garbage generates nitrogen gas under the condition of lacking sufficient free oxygen atoms, thereby reducing the concentration of nitrogen oxides. Among them, the local reducing atmosphere can control the oxygen concentration in the mixed primary air duct 450 to 15% to 18%, and the temperature in the mixed primary air duct 450 to 130℃ to 210℃, and the two conditions are formed in coordination.

[0045] Since domestic waste is different from coal, most of the combustible matter in domestic waste is released into the combustion chamber in the form of volatile matter after entering the combustion chamber, and the local reducing atmosphere is conducive to reducing the generation of nitrogen oxides. As the domestic waste moves backward on the grate 420 and gradually completes combustion, the remaining ash after combustion is discharged from the combustion chamber through the slag discharge port arranged at the tail of the grate.

[0046] In order to achieve a reducing atmosphere in the lower part of the combustion chamber 400, the volatiles released by the domestic waste are not completely burned, and these volatiles flow to the upper part of the combustion chamber 400 along with the combustion products. The secondary air entering the combustion chamber 400 from the upper part of the grate 420 through the secondary air duct 410 provides sufficient oxygen as the burning air, and further mixes with the unburned volatiles in the combustion products to burn, and the carbon element therein is fully oxidized to be converted into carbon dioxide, and the hydrogen element is fully oxidized to be converted into water, and heat energy is fully released.

[0047] The combustion product (i.e., flue gas) that is completely burned and fully releases heat energy enters the waste heat boiler flue 300 from the outlet at the top of the combustion chamber 400. As the flue gas moves toward the flue outlet 350, it exchanges heat with the evaporator 310, superheater 330, and economizer 340 arranged in the waste heat boiler flue 300, and gradually heats the boiler feed water entering the economizer into superheated steam. After heat release, the flue gas temperature at the outlet of the economizer 340 is reduced to about 180°C to 250°C. Unlike traditional coal-fired boilers, the waste incineration flue gas is highly sticky and corrosive, resulting in the waste heat boiler incineration The exhaust gas temperature at the outlet of the economizer 340 gradually increases as the operating time increases. In the technical solution of the utility model, in order to avoid the problem of low-temperature corrosion, an air preheater is no longer arranged at the economizer outlet, which greatly saves cost and equipment space.

[0048] Supplying cold primary air from the lower part of the grate 420 is not conducive to the stable combustion of domestic waste. The utility model sets a low-temperature circulation flue 232 in the flue at the rear end of the economizer and a high-temperature circulation flue 242 in the flue at the front end of the economizer. Through these two flues, low-temperature flue gas and high-temperature flue gas are drawn out from the flue 300 of the waste heat boiler as the heat source of the primary air, and the primary air is heated by mixing with the primary air. The flue gas temperature of the low-temperature flue gas and the high-temperature flue gas is higher than the temperature of the primary air, and the oxygen concentration of the low-temperature flue gas and the high-temperature flue gas is lower than the oxygen concentration of the primary air. Therefore, the mixture of the flue gas and the primary air after mixing is called mixed primary air, the temperature of the mixed primary air is higher than the temperature of the primary air, and the oxygen concentration of the mixed primary air is lower than that of the primary air.

[0049] Some preferred operating principles of the embodiments of the present utility model are as follows:

[0050] 1. Different from the existing partition wall heating method, the flue gas is mixed with the primary air to heat the primary air. There is no area at the air preheater outlet where the flue gas temperature, air temperature and pipe wall temperature are the lowest, and there is no problem of low-temperature corrosion of the heating surface at the lowest temperature.

[0051] 2. The acid dew point temperature of flue gas is related to the concentration of acidic gas and water vapor in the flue gas. The higher the concentration, the higher the acid dew point temperature, that is, the higher the condensation temperature of acidic gas. The utility model allows flue gas to be mixed with primary air through creative structural design. Although the temperature of the mixed primary air after mixing is lower than the flue gas temperature before mixing, the risk of acidic gas condensation is increased; however, the concentration of acidic gas and water vapor in the mixed primary air is also significantly reduced, reducing the risk of acidic gas condensation.

[0052] 3. The primary air is heated by mixing the flue gas with the primary air. Although there are both factors that increase and reduce the risk of acid gas condensation in the mixed primary air, the utility model further takes measures to ensure that acid gas condensation does not occur in the mixed primary air. The specific design idea is to take into account that during the operation of the waste incineration waste heat boiler, the flue gas temperature at the economizer outlet varies greatly. In order to ensure that the temperature of the mixed primary air is above the flue gas acid dew point temperature, the structure of the utility model allows two flue gases with different temperatures to be drawn from the flue at the economizer flue gas outlet and the economizer flue gas inlet end to be mixed, increasing the adjustment range of the mixed primary air temperature, ensuring that the mixed primary air temperature is above the flue gas acid dew point temperature, and ensuring that acid gas condensation in the mixed primary air does not occur, causing corrosion of the mixed primary air duct, wind chamber and grate.

[0053] In addition, the existing waste incineration process produces a large amount of nitrogen oxides, an atmospheric pollutant. In order to achieve the emission of nitrogen oxides in flue gas that meets the standards, the existing technology requires denitrification of the waste incineration flue gas, including SNCR denitrification and SCR denitrification, which will inevitably increase the initial investment cost and operating cost of environmental protection facilities. The utility model uses a creative design of the system structure to extract part of the flue gas and mix it with the primary air, which not only increases the temperature of the mixed primary air, but also avoids the low-temperature corrosion problem of acid gas condensation in the mixed primary air while heating the primary air. It also reduces the oxygen concentration of the mixed primary air, and adjusts the ratio of the circulating flue gas volume to the primary air volume, which can effectively adjust the oxygen concentration of the mixed primary air. Reducing the oxygen concentration of the mixed primary air is beneficial to creating a local reducing atmosphere in the waste incineration area above the grate, and reducing the nitrogen oxides generated by the immediate incineration into nitrogen. It can be seen that the technical solution of the utility model reduces the generation of nitrogen oxides during the waste incineration process, and reduces the pressure and cost of flue gas denitrification.

[0054] The waste incineration waste heat boiler system provided by the embodiment of the utility model solves the problem of reducing the concentration of nitrogen oxides on the one hand, and on the other hand, solves the problem of strong stickiness and corrosiveness of waste incineration flue gas without using an air preheater, while avoiding the problem of space occupation and high cost caused by the use of air preheaters in the prior art.

[0055] According to the waste incineration waste heat boiler system in the utility model, the following control methods can be adopted, specifically including:

[0056] 1. Control the primary air flow in the mixed primary air duct so that:

[0057] V 1A =COE 1A ×F STM ;

[0058] in,

[0059] V 1A For the air flow rate of the first run, Nm 3 / s; V 1A Measured and displayed by the primary air flow meter 110;

[0060] F STM is the steam production of the waste heat boiler, in kg / s; it is measured and displayed by the superheated steam flow meter 338;

[0061] COE 1A is the primary air steam coefficient, in Nm 3 / kg, is the air flow rate V of the incinerator during one operation 1A The amount of steam generated by the waste heat boiler F STM The ratio ranges from 0.70 to 1.15 Nm3 / kg.

[0062] 2. Control the primary air oxygen volume concentration in the mixed primary air duct so that:

[0063]

[0064] in:

[0065] O mix is the volume concentration of mixed primary air oxygen, %;

[0066] V 1A For the air flow rate of the first run, Nm 3 / h;

[0067] V HG is the high temperature circulating flue gas flow rate, Nm 3 / s; measured by high temperature circulating flue gas flow meter 241;

[0068] V LG is the low-temperature circulating flue gas flow rate, Nm 3 / s; measured by low temperature circulating flue gas flow meter 231;

[0069] O Rec It is the volume concentration of oxygen in the circulating flue, ranging from 3% to 10%; it is measured by the online flue gas analysis system 355 and the unit is %.

[0070] 3. Control the primary air temperature t in the mixed primary air duct aim,1Amix , so that:

[0071] t aim,1Amix =t adp,1Amix +t S,Cor +t yl ;

[0072] in,

[0073] t aim,1Amix is the target mixed primary air temperature, °C;

[0074] t adp,1Amix is the acid dew point temperature of the mixed primary air, in °C, which can be calculated by any of the following two formulas:

[0075] t adp,1Amix =18.0×M ar +134.83;

[0076] Among them, M ar is the mass percentage of the received basis moisture content of the garbage entering the furnace, %;

[0077] t S,CorThe fuel sulfur content correction factor, in °C, can be calculated using the following formula:

[0078] t S,Cor =65.46×S ar -6.42;

[0079] S ar is the mass percentage of sulfur content of the waste entering the furnace, %;

[0080] t yl It is the margin, and its value range is 2~15℃.

[0081] Preferably, the oxygen concentration in the mixed primary air duct 450 is in the range of 15% to 18%, and the temperature in the mixed primary air duct 450 is in the range of 130°C to 210°C.

[0082] In this embodiment, a waste incineration waste heat boiler system with a steam production of 72 tons / hour is taken as an example, and according to the target temperature and target oxygen concentration requirements of the mixed primary air, the flow rates of different flue gas oxygen concentrations, different low-temperature flue gas temperatures and high-temperature flue gas temperatures are controlled to achieve the desired effect. The details are as follows:

[0083] Exhaust temperature control process

[0084] The oxygen concentration of the mixed primary air is required to be controlled at 16.5% and the temperature is controlled at 145°C. When the oxygen concentration of the flue gas is 5%, when the low-temperature flue gas temperature rises from 200°C to 235°C, and the corresponding high-temperature flue gas temperature rises from 350°C to 385°C, the low-temperature circulating flue gas flow rate entering the circulating flue 200 increases from 5.05Nm 3 / s increased to 6.84Nm 3 / s, accordingly, the high-temperature circulating flue gas flow rate entering the circulating flue 200 is 2.70Nm 3 / s down to 0.91Nm 3 / s. The specific changes are shown in Table 1.

[0085] Control process of mixed primary air oxygen concentration

[0086] The temperature of the mixed primary air is controlled at 145°C; when the oxygen concentration of the flue gas is 5%, when the temperature of the low-temperature circulating flue gas is 200°C, and the temperature of the high-temperature circulating flue gas is 350°C, the oxygen concentration of the mixed primary air is required to increase from 15.5% to 17.5%, and the flow rate of the low-temperature circulating flue gas entering the circulating flue 200 increases from 8.71Nm 3 / s down to 1.97Nm 3 / s, accordingly, the high-temperature circulating flue gas flow rate entering the circulating flue 200 is 1.66Nm 3 / s increased to 3.57Nm 3 / s. The specific changes are shown in Table 2.

[0087] Control process of mixed primary air temperature

[0088] When the oxygen concentration of flue gas is 5%, when the temperature of low-temperature circulating flue gas is 200℃, the temperature of high-temperature circulating flue gas is 350℃, and the oxygen concentration of mixed primary air is required to be 18%, when the temperature of mixed primary air is controlled to rise from 120℃ to 140℃, the flow rate of low-temperature circulating flue gas entering the circulating flue 200 increases from 4.35Nm 3 / s down to 1.36Nm 3 / s, accordingly, the high-temperature circulating flue gas flow rate entering the circulating flue 200 is 0.22Nm 3 / s increased to 3.21Nm 3 / s. The specific changes are shown in Table 3.

[0089] Flue gas oxygen concentration control process

[0090] The oxygen concentration of the mixed primary air is required to be controlled at 17.5% and the temperature is controlled at 145°C. When the low-temperature flue gas temperature is 200°C and the high-temperature flue gas temperature is 350°C, the oxygen concentration of the flue gas rises from 3% to 8%, and the flow rate of the low-temperature circulating flue gas entering the circulating flue 200 increases from 0.90Nm 3 / s increased to 3.44Nm 3 / s, accordingly, the high-temperature circulating flue gas flow rate entering the circulating flue 200 is 3.88Nm 3 / s down to 3.15Nm 3 / s. The specific changes are shown in Table 4.

[0091] Table 1

[0092]

[0093]

[0094] Table 2

[0095]

[0096]

[0097] Table 3

[0098]

[0099]

[0100] Table 4

[0101]

[0102]

[0103] The above examples show that even if the flue gas oxygen concentration and temperature of the waste heat boiler flue ... gas flue flue gas flue gas flue gas flu

[0104] (1) Ensure that the temperature of the mixed primary air is above the acid dew point temperature, effectively use the flue gas of the boiler to heat the primary air, and effectively solve the low-temperature corrosion problem of the existing technology that uses the flue gas of the waste heat boiler to heat the primary air. Save the amount of air extraction required for the existing technology to use the boiler or steam turbine to extract steam to heat the primary air, increase the power generation of this part of steam or the amount of steam supplied to the outside, and improve the resource utilization rate of waste incineration treatment.

[0105] (2) Further, the manufacturing cost and space occupied by the air preheater for steam heating the primary air are reduced, and the power consumption of the primary air fan is reduced by reducing the air flow resistance.

[0106] (3) The oxygen concentration of the mixed primary air entering the combustion chamber from the bottom of the grate is controllable, which ensures the effective and stable combustion of the garbage. At the same time, it is beneficial to control the local reducing atmosphere of the garbage incineration process and effectively reduce the generation of nitrogen oxides and the concentration of nitrogen oxides in the combustion products.

[0107] Among them, in the technical solution of the utility model, if it is necessary to obtain the calorific value of the primary air, the calorific value of the high-temperature circulating flue gas, the calorific value of the low-temperature circulating flue gas and the calorific value of the mixed primary air, the relationship is calculated by the following formula:

[0108] Q 1A +Q HG +Q LG =Q 1Amix ;

[0109] in:

[0110] Q 1Amix is the calorific value of the mixed primary air, kW;

[0111] Q 1A is the calorific value of primary air, Q HG is the calorific value of high temperature circulating flue gas, Q LG is the calorific value of low-temperature circulating flue gas, kW

[0112] Heat value of primary air Q 1A Calculated by the following formula

[0113] Q 1A =V 1A ×K 1A ×t 1A ;

[0114] Where: K 1Ais the specific heat of primary air, in kJ / (Nm 3 ×℃), is the primary air temperature t 1A The function can be calculated by the following formula:

[0115] K 1A =1.2945+6.1408×10 -5 ×t 1A ;

[0116] t 1A is the primary air temperature, in °C, which can be measured and displayed by the primary air thermometer 105;

[0117] Q HG and Q LG is the calorific value of high-temperature circulating flue gas and the calorific value of low-temperature circulating flue gas, which can be calculated by the following formula:

[0118] Q HG =V HG ×K HG ×t HG ;

[0119] Q LG =V LG ×K LG ×t LG ;

[0120] K HG is the specific heat of high temperature circulating flue gas, in kJ / (Nm 3 ×℃), is the high temperature circulating flue gas temperature t hG The function can be calculated by the following formula:

[0121] K HG =1.373+1.703×10 -4 ×t HG ;

[0122] t HG is the high-temperature circulating flue gas temperature, in °C, which can be measured and displayed by the high-temperature flue gas thermometer 244;

[0123] K LG is the specific heat of low-temperature circulating flue gas, in kJ / (Nm 3 ×℃), is the low circulating flue gas temperature t HG The function can be calculated by the following formula:

[0124] K LG =1.373+1.703×10 -4 ×t LG ;

[0125] t LGis the low-temperature circulating flue gas temperature, in °C, which can be measured and displayed by the low-temperature flue gas thermometer 234;

[0126] Heat value of mixed primary air Q 1Amix Calculated by the following formula:

[0127] Q 1Amix =V 1Amix ×K 1Amix ×t 1Amix ;

[0128] Where: K 1A Mix is ​​the specific heat of the mixed primary air, in kJ / (Nm 3 ×℃), is the primary air temperature t 1Amix The function can be calculated by the following formula:

[0129] K 1Amix =1.325+9.820×10 -5 ×t 1Amix ;

[0130] t 1Amix It is the mixed primary air temperature in °C, which can be measured and displayed by the mixed primary air thermometer 460.

Claims

1. A waste incineration waste heat boiler system, characterized in that: It includes a primary air duct (100), a circulating flue (200), a waste heat boiler flue (300) and a combustion chamber (400); The inlet of the circulating flue (200) is connected to the low-temperature circulating flue (232), and the low-temperature circulating flue (232) is connected to the waste heat boiler flue (300); the inlet of the circulating flue (200) is also connected to the high-temperature circulating flue (242), and the high-temperature circulating flue (242) is connected to the waste heat boiler flue (300); The inlet of the primary air duct (100) is connected to a primary air fan (140); the primary air duct (100) is also connected to an air preheater (150); The inlet of the steam-water side of the air preheater (150) is also connected to the air preheater steam pipe (160) used for heating, and the outlet is connected to the air preheater drain pipe (130); the air preheater steam pipe (160) is connected to the steam drum (320) through the saturated steam outlet pipe (333); The outlet of the primary air duct (100) is connected to the outlet of the circulating flue (200) and merges into a mixed primary air duct (450), and the mixed primary air duct (450) is connected to the wind chamber (440) at the bottom of the combustion chamber (400); The inlet of the waste heat boiler flue (300) is connected to the flue gas outlet of the combustion chamber (400); an evaporator (310), a superheater (330) and an economizer (340) are arranged in the waste heat boiler flue (300), and the economizer (340) is arranged at the last section of the flue gas flowing in the waste heat boiler flue (300); the waste heat boiler flue (300) is provided with a flue outlet (350); the evaporator (310) is connected to the steam drum (320) through a steam-water circulation pipe (315); the inlet of the superheater (330) is connected to a superheated steam pipeline (336), and the superheated steam pipeline (336) is connected to the steam drum (320) through a saturated steam outlet pipe (333); the outlet of the economizer (340) is connected to the steam drum (320) through a water supply pipe (341).

2. The waste incineration waste heat boiler system according to claim 1, characterized in that: A primary air flow meter (110) is provided in the primary air duct (100), and a primary air temperature meter (105) is provided in the primary air duct (100) at the outlet of the air preheater (150); and a superheated steam flow meter (338) is provided in the inlet pipe of the superheater (330).

3. The waste incineration waste heat boiler system according to claim 1, characterized in that: The oxygen concentration in the mixed primary air duct (450) ranges from 15% to 18%, and the temperature in the mixed primary air duct (450) ranges from 130° C. to 210° C.

4. The waste incineration waste heat boiler system according to claim 1, characterized in that: A second circulating flue (413) is also provided, so the second circulating flue (413) is provided on the circulating flue (200) and is connected to the combustion chamber (400) through a circulating air port (417) provided on the upper part of the grate (420), and a circulating flue baffle 2 (415) is provided on the second circulating flue (413).

5. The waste incineration waste heat boiler system according to claim 1, characterized in that: The air preheater steam pipeline (160) is provided with a heating steam regulating valve (170) and a heating steam flow meter (180).

6. The waste incineration waste heat boiler system according to claim 1, characterized in that: The mixed primary air duct (450) is provided with a mixed primary air thermometer (460); A flue gas circulation fan (210) and a dust collector (220) are arranged on the circulating flue (200), and a circulating flue gas thermometer (203) and a circulating flue baffle (206) are arranged on the connecting pipe between the flue gas circulation fan (210) outlet and the mixed primary air duct (450).

7. The waste incineration waste heat boiler system according to claim 1, characterized in that: The low-temperature circulation flue (232) is provided with a low-temperature circulation flue gas flowmeter (231) and a low-temperature circulation flue duct baffle (233), and a low-temperature flue gas thermometer (234) is provided at the connection port between the low-temperature circulation flue (232) and the waste heat boiler flue (300) and at the rear side of the economizer (340); The high-temperature circulation flue (242) is provided with a high-temperature circulation flue gas flowmeter (241) and a high-temperature circulation flue duct baffle (243), and a high-temperature flue gas thermometer (244) is provided at the connection port between the high-temperature circulation flue (242) and the waste heat boiler flue (300) which is located in front of the economizer (340).

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