Ultra-clean economical energy-saving boiler combined system

Abstract

The present invention discloses an ultra-clean energy-saving boiler combined system, including a water-coal slurry system, a low-cost coal-powder system, a boiler-designed coal-powder system, a flue and boiler waste heat heating system, a boiler steam supply system, a reducing agent supply system, a furnace combustion system and a furnace denitrification system. Coal enters the water-coal slurry system for preparation, enters the low-cost coal-powder system for preparation, and the boiler raw coal powder system can use coal types for preparation; the prepared fuel enters the boiler combustion system according to the boiler demand ratio and is sprayed into the furnace for combustion. Since the water-coal slurry combustion reduces the combustion zone temperature, NO is reduced X To eliminate the production of denitrification mixture, steam, water-coal slurry and other denitrification substances are sprayed into the pipeline network near the large screen, the pipeline network and nozzles arranged on and near the burner to ensure the energy-saving and environmentally friendly use of the boiler.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection equipment, and more specifically to an ultra-clean, economical and energy-saving boiler combined system which can be used in various boilers such as coal-fired boilers and oil-fired boilers and waste heat utilization boilers. Background Art

[0002] At the beginning of 2019, the price of coal used in power plants was about 800 yuan per ton, and the average fuel cost per kilowatt-hour was about 0.27 yuan. The on-grid electricity price was about 0.39 yuan (different provinces have different on-grid electricity prices). The price of inferior coal is much lower, such as lignite, which is about 100 yuan per ton. At present, most boilers cannot directly use low-cost coal such as lignite to reduce the cost of coal burning in power plants.

[0003] At present, coal-fired power generation units produce NO X and SO2, which seriously pollutes the atmosphere. At present, boiler desulfurization technologies include wet desulfurization technology, dry desulfurization technology, and semi-dry desulfurization technology. The desulfurizer is mainly CaCO3, etc.; the mainstream denitrification technologies include SNCR, SCR, and SNCR and SCR combined technology, as well as other boiler denitrification technologies. The denitrifiers used are urea, ammonia water, liquid ammonia, ammonium bicarbonate, etc.

[0004] Large units of 300,000 and 600,000 kilowatts basically use SCR denitrification technology. When the 600,000 kilowatt unit is in normal use, the catalyst increases the power of the boiler induced draft fan by about 1,000 kilowatts. The power of urea pyrolysis using electric heating is about 1,000 kilowatts. In addition, steam heating is required when urea is dissolved, which requires more energy.

[0005] The current denitrification technology generates ammonium bisulfate when in use, which forms a butter-like substance at the air preheater, blocking the air preheater, causing increased wind resistance and energy consumption of the boiler induced draft fan. After the catalyst fails, it is considered a hazardous waste, which is highly polluting to the environment. The current denitrification technology costs about 1,800 yuan per ton for the denitrification reducing agent urea, and about 500 yuan per ton for ammonium bicarbonate.

[0006] At present, the cost of coal remains high, and the coal consumption of power plant units is high when they are running at low load. How to improve the economic benefits of power plants while meeting environmental protection requirements is a serious problem related to the survival of power plants. At present, low-cost coal such as lignite can reduce the cost of boiler coal by 30% after being modified and used in current pulverized coal furnaces. However, lignite is prone to spontaneous combustion, and its natural storage period is generally about two months. It is easy to spontaneously combust, and it is difficult to store it under normal conditions. Conventional boilers can only use lignite after being modified.

[0007] The water-coal slurry preparation does not have the combustion phenomenon seen in the preparation of low-cost coals such as lignite, and can be stored for a long time. The water-coal slurry combustion system produces low nitrate content when working, which can reduce the denitrification cost of the boiler.

[0008] Due to the use of water-coal slurry to transform the boiler, the water vapor content in the boiler flue gas increases, the flue gas carries away more heat, and the thermal efficiency of the boiler is lower than that of the coal-fired boiler. Summary of the invention

[0009] In view of the deficiencies of the prior art, the present invention provides an ultra-clean, economical and energy-saving boiler combined system.

[0010] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: an ultra-clean, economical and energy-saving boiler combined system is used in various types of coal-fired, oil-fired and other boilers and waste heat utilization boilers, including a coal yard, a water-coal slurry system, a low-cost coal powder system, a boiler designed coal type coal powder system, a boiler and flue waste heat heating system, a steam switching system, a boiler and flue waste heat steam system, a boiler steam supply system, a denitrification agent heating system, a denitrification agent and steam mixing system, a denitrification agent mixing and distribution system, a denitrification agent dissolution and storage system, and a combustion system. The coal yard is respectively connected to the water-coal slurry system, the low-cost coal powder system, and the boiler designed coal type coal powder system, and the combustion system is respectively connected to the water-coal slurry system, the low-cost coal powder system, and the boiler designed coal type coal powder system. system, the water-coal slurry system is connected to the steam switching system, the steam switching system is respectively connected to the boiler and flue waste heat steam system, the boiler steam supply system, the denitrification agent heating system, the denitrification agent and steam mixing system, the denitrification agent mixing distribution system, the boiler and flue waste heat steam system is connected to the boiler and flue waste heat heating system, the denitrification agent dissolution and storage system is connected to the denitrification agent mixing distribution system, the denitrification agent mixing distribution system is connected with the denitrification spray gun at the large screen in the furnace, the spray gun near the burner, and the spray gun on the burner. The flue gas after combustion in the combustion system flows through the superheater, economizer, SCR denitrification area, flue and boiler waste heat heating system, electrostatic precipitator, desulfurization and dehumidification, and chimney in the boiler in sequence and is discharged into the atmosphere.

[0011] The water-coal slurry system further comprises coal storage facilities for coal transportation in a coal yard, a coal transportation system, a water-coal slurry preparation system, and a water-coal slurry storage system.

[0012] The low-cost coal system further comprises coal grinding equipment and conveying equipment.

[0013] Furthermore, the water-coal slurry steam switching system can switch the steam for heating the water-coal slurry, and can switch the steam for heating the water-coal slurry to steam from flue and boiler waste heat subsystem or boiler, etc., to heat the water-coal slurry to different required temperatures and pressures, and spray it into the furnace for combustion according to the temperature in the boiler furnace. The combustion characteristics of the water-coal slurry are used to reduce the amount of nitrate produced by the boiler.

[0014] Furthermore, the steam switching system of the water-coal slurry system distributes water vapor to the denitrification agent heating system, the denitrification agent and steam mixing system, and the denitrification agent mixing and distribution system.

[0015] Furthermore, the denitrification agent heating system is switched by a steam switch to use water vapor from the flue and boiler waste heat steam system or the boiler steam supply system.

[0016] The denitration system further includes denitration at the burner, denitration at the large screen, and SCR denitration.

[0017] Furthermore, the flue and boiler waste heat heating system is provided with a heat exchanger, and the heat exchanger exchanges heat or other waste heat with the flue gas in the flue and the flue gas in the boiler.

[0018] Furthermore, the heat exchanger is placed inside the flue or boiler or close to the outside of the flue or boiler as required.

[0019] Furthermore, the heat exchanger of the flue and boiler waste heat heating system is provided with a soot blowing device.

[0020] Furthermore, the soot blowing device is a sonic soot blowing device, a steam soot blowing device or a vibration soot removing device.

[0021] Furthermore, the denitrification nozzles and spray guns near the large screen superheater are evenly distributed inside and outside the furnace to ensure that the denitrification mixed gas can be separated from the NO in the flue gas. X Mix the reaction thoroughly.

[0022] Furthermore, the denitrification spray guns at the burner are distributed on or near the burner.

[0023] Furthermore, the low-cost coal grinding system can adapt to the grinding temperature required for different types of coal, and the low-cost coal grinding system is achieved by modifying or adding a new coal grinding system.

[0024] The combustion system in the furnace further includes a water-coal slurry burner, a low-cost coal combustion system, and a designed coal combustion system. The above burners are arranged or switched according to different coal types to ensure economical combustion of boiler coal types.

[0025] Further, the water-coal slurry burner produces low (NO X Around 44 mg / m3). By arranging the water-coal slurry burner, the flame temperature of the boiler burner is reduced, and the NO generated during boiler combustion is reduced. X The amount of NO is reduced by spraying high-temperature steam into the flame zone through the steam generated from the boiler waste heat or the arrangement of the boiler's steam in the boiler burner accessories. X Reduce the amount of NO produced by the boiler and denitrify it XThe amount produced meets the national ultra-low emission standards, and the SCR area has a spare denitrification catalyst. Whether to use SCR denitrification is determined based on the needs of the boiler.

[0026] The measurement system further comprises the measurement systems of all devices, and the measurement system is connected to a DCS centralized control system.

[0027] The control system further includes valves and pump actuators, and the valves and pump actuators are connected to motors or pneumatic components.

[0028] In summary, the present invention improves the current boiler denitrification efficiency, reduces boiler denitrification energy consumption, reduces boiler coal burning costs, improves the benefits of power generation enterprises, and reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a system block diagram of the ultra-clean, economical and energy-saving boiler combined system of the present invention. DETAILED DESCRIPTION

[0030] Reference Figure 1 An embodiment of the ultra-clean energy-saving boiler combined system of the present invention is further described.

[0031] The ultra-clean economical and energy-saving boiler combined system includes a coal yard 9, a water-coal slurry system 8, a low-cost coal powder system 7, a boiler design coal type coal powder system 6, a flue and boiler waste heat heating system 18, a steam switcher 14, a boiler steam supply system 10, a denitrification agent dissolution storage system 13, a combustion system 5 and a furnace denitrification pipe network 2, and spray guns 3 and 4, etc. The coal yard 9 is respectively connected to the water-coal slurry system 8, the boiler design coal type coal powder system 6, and the low-cost coal powder system 7, the combustion system 5 is respectively connected to the water-coal slurry system 8, the boiler design coal type coal powder system 6, and the low-cost coal powder system 7, the water-coal slurry system 8 is connected to the steam switching system 14, and the steam cut The exchange system 14 connects the flue and the boiler waste heat steam system 11, the boiler steam supply system 10, the denitrification agent heating system 12, the denitrification agent and steam mixing system 15, and the denitrification agent mixing and distribution system 16. The boiler waste heat steam system 11 is connected to the boiler and the waste heat utilization pipeline system 18 in the flue. The denitrification agent mixing and distribution system 16 is connected with the furnace denitrification pipeline network 2, and the spray guns 3 and 4. The flue gas after combustion by the burner 5 in the boiler 1 flows through the superheater, economizer, SNCR denitrification 17, air preheater, boiler and flue inside and outside waste heat utilization pipeline system 18, enters the electrostatic precipitator 19, and is discharged into the atmosphere through the chimney 21 through the desulfurization and wet removal 20.

[0032] The different coals in the coal yard 9 are transported to the water-coal slurry system 8, the boiler design coal type pulverized coal system 6, and the low-cost coal pulverized coal system 7 according to the coal types and process requirements, and the particles and mixed states suitable for combustion are manufactured and enter the combustion system 5 for combustion in the respective suitable combustion areas; when the water-coal slurry burner in the combustion system 5 burns the water-coal slurry, it has an inhibitory effect on the nitrate produced by the combustion of other coal types in the combustion system 5 and has a removal effect on the nitrate produced by other burners; the spray gun 4 on the boiler burner and the ones arranged near the burner The spray gun 3 blows an appropriate amount of water vapor mixture at a suitable temperature into the combustion flame to produce substances and factors that inhibit the production of nitrate, thereby reducing the amount of nitrate produced; the high-temperature flue gas passes through the large screen at the large screen at the large screen The denitrification spray gun (pipe network) 2 is further deeply denitrated to reduce the nitrate content in the boiler to an extremely low level. The boiler flue gas after combustion flows in turn through the superheater, economizer, SNCR denitrification 17 in the boiler, the waste heat utilization pipeline system 18 inside and outside the boiler and the flue, the air preheater, enters the electrostatic precipitator 19, and is discharged into the atmosphere through the chimney 21 through the desulfurization and wet removal 20.

[0033] The use of water-coal slurry for combustion increases the amount of water vapor in the flue gas, and takes away more waste heat. The waste heat is utilized through the flue and the waste heat utilization pipeline system 18 inside and outside the boiler to improve the efficiency of the boiler. When the system that utilizes the waste heat of the flue boiler to evaporate water is in operation, the low-temperature water is first heated to a certain temperature in the flue, and the heated water or water vapor enters the boiler for further heating (partially participating in the circulation of the main engine system in the boiler), and the generated high-temperature water vapor enters the steam switching system. The water vapor from the boiler enters the steam switching system through a pipeline. The steam switching system switches according to the boiler combustion conditions and the steam pressure requirements. The water vapor coming out of the steam switching system is distributed through pipelines to the water-coal slurry system 8, the denitrification agent heating system 12, the denitrification agent and steam mixing system 15, and the denitrification agent mixing distribution system 16, and then enters the water-coal slurry burner on the steam combustion system 5 at the large screen and the denitrification pipeline network 2 at the large screen, and the spray guns 3 and 4 on and near the burner.

[0034] The burners include conventional coal burners, low-cost coal burners, and water-coal slurry burners. According to the different types of boilers, various burners are reasonably distributed to ensure the economical operation of boilers.

[0035] The denitrification spray gun and pipe network are reasonably arranged on or near the burner, and an appropriate amount of water vapor is sprayed into the boiler according to the boiler operating conditions to ensure the minimum nitrate production and denitrification effect of the boiler.

[0036] Calculation of economic efficiency of low-cost coal:

[0037] Take lignite as an example. The cost of burning coal accounts for about 70% of the total cost of power generation enterprises. The price of lignite is about 200 yuan / ton, and the water content is relatively high. Compared with the current power plant thermal coal of about 800 yuan / ton, it has a great price advantage. According to public information, the use of lignite can reduce the cost of burning coal by about 30%. A 600,000-kilowatt unit burning lignite can increase profits by about 100 million yuan a year.

[0038] Environmental and economic calculation:

[0039] At present, the flue gas volume of a 600MW unit is about 2000000m3 when the output is 100%. 3 ,NO X The content is 500 mg / m 3 , the ammonia-nitrogen ratio is 1:1 for calculation parameters:

[0040] The annual catalyst operating depreciation cost is approximately 3 million yuan / year.

[0041] Total amount of nitrate (all calculated as NO): 2000000×0.5=1000000 (g)

[0042] Total amount of ammonia required: 1,000,000 ÷ 30 × 17 = 566,666 (g) = 566.7 kg

[0043] The annual demand for denitrification agent is about 566.7×4000=2266 tons

[0044] The cost of using denitrification agent is about 3 million yuan per year

[0045] When urea is pyrolyzed, the electric heating power of the pyrolysis furnace is about 1000 kilowatts.

[0046] The increased wind resistance of SCR is about 1200 Pa, and the increased induced draft fan power is about 1000 kW. (excluding the energy consumption caused by the increased air preheater resistance of ammonium bisulfate)

[0047] This case is a mixed combustion of three burners, water-coal slurry reduces NO X The low NOx emission and the low temperature of the flame zone of the pulverized coal burner during the combustion of water-coal slurry reduce the thermal NOx emission from other burners. X . In addition, the denitrification of the denitrification spray gun (pipe network) in the burner flame zone can be used. The boiler can meet or basically meet the ultra-low emission standards for denitrification without putting the current SNCR and SCR denitrification system facilities of the boiler into operation. The following operating costs can be reduced: the urea pyrolysis furnace is cancelled and the pyrolysis energy consumption is reduced by 1,000 kilowatts.

[0048] Eliminating the SCR catalyst area reduces wind resistance by about 1200 Pa and reduces induced draft fan power by about 1000 kW. (Excluding the energy consumption caused by the increased air preheater resistance due to ammonium bisulfate)

[0049] The annual reduction in catalyst operating depreciation costs is approximately RMB 3 million per year.

[0050] The annual cost of using denitrification agents is reduced by approximately RMB 3 million per year.

[0051] Since the burner is modified to use water-coal slurry combustion, etc., the NO X Limit the time of excessive emissions and reduce air pollution.

[0052] This embodiment preferably also includes a measurement system for all devices in the measurement system, and the measurement system is connected to a DCS centralized control system. The DCS centralized control system controls the execution system through data measured by the measurement system and external instructions to ensure stable operation of the system.

[0053] This embodiment preferably also includes valves and pump actuators, which are connected to motors or pneumatic components to ensure stable operation of the system.

[0054] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An ultra-clean, economical and energy-saving boiler combined system, characterized by: The ultra-clean economical and energy-saving boiler combined system includes a coal yard, a water-coal slurry system, a low-cost coal powder system, a boiler-designed coal powder system, a boiler and flue waste heat heating system, a steam switching system, a boiler and flue waste heat steam system, a boiler steam supply system, a denitrification agent heating system, a denitrification agent and steam mixing system, a denitrification agent mixing and distribution system, a denitrification agent dissolution and storage system, and a combustion system. The coal yard is respectively connected to the water-coal slurry system, the low-cost coal powder system, and the boiler-designed coal powder system. The combustion system is respectively connected to the water-coal slurry system, the low-cost coal powder system, and the boiler-designed coal powder system. The water-coal slurry system is connected to the steam switching system. The steam switching system is respectively connected to the boiler and flue waste heat steam system, the boiler steam supply system, the denitrification agent heating system, the denitrification agent and steam mixing system, and the denitrification agent mixing distribution system. The boiler and flue waste heat steam system is connected to the boiler and flue waste heat heating system. The denitrification agent dissolution and storage system is connected to the denitrification agent mixing distribution system. The denitrification agent mixing distribution system is connected with the denitrification spray gun at the large screen in the furnace, the spray gun near the burner, and the spray gun on the burner. The flue gas after combustion in the combustion system flows through the superheater, economizer, SCR denitrification area, flue and boiler waste heat heating system, electrostatic precipitator, desulfurization and dehumidification, and chimney in the boiler in sequence and is discharged into the atmosphere.

2. The ultra-clean, economical and energy-saving boiler combined system according to claim 1 is characterized by: The water-coal slurry system comprises coal storage facilities for coal transportation in a coal yard, a coal transportation system, a water-coal slurry preparation system, and a water-coal slurry storage system.

3. The ultra-clean, economical and energy-saving boiler combined system according to claim 1 is characterized by: The low-cost coal powder system comprises coal grinding equipment and conveying equipment.

4. The ultra-clean, economical and energy-saving boiler combined system according to claim 1 is characterized by: The flue and boiler waste heat heating system is provided with a heat exchanger, and the heat exchanger is provided with a soot blowing device, which is a sonic soot blowing device or a steam soot blowing device.

5. The ultra-clean, economical and energy-saving boiler combined system according to claim 1 is characterized by: The denitrification agent heating system is switched by a steam switcher, and the switching uses water vapor from the flue and boiler waste heat steam system or the boiler steam supply system.

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