CN104511234A - Clean emission system and method for fluidized bed boiler - Google Patents
Clean emission system and method for fluidized bed boiler Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 13
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 99
- 239000003546 flue gas Substances 0.000 claims abstract description 99
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 73
- 230000023556 desulfurization Effects 0.000 claims abstract description 70
- 238000002485 combustion reaction Methods 0.000 claims abstract description 22
- 239000007789 gas Substances 0.000 claims abstract description 21
- 239000003054 catalyst Substances 0.000 claims description 15
- 239000000779 smoke Substances 0.000 claims description 13
- 239000000446 fuel Substances 0.000 claims description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 6
- 239000000295 fuel oil Substances 0.000 claims description 3
- 239000003345 natural gas Substances 0.000 claims description 3
- 239000000839 emulsion Substances 0.000 claims 2
- 230000001737 promoting effect Effects 0.000 claims 2
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 238000005457 optimization Methods 0.000 abstract description 2
- 239000000809 air pollutant Substances 0.000 abstract 1
- 231100001243 air pollutant Toxicity 0.000 abstract 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 17
- 239000000428 dust Substances 0.000 description 10
- 229910021529 ammonia Inorganic materials 0.000 description 7
- 239000003638 chemical reducing agent Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 3
- 238000003915 air pollution Methods 0.000 description 3
- 239000004202 carbamide Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
一种用于流化床锅炉的洁净排放方法，在流化床锅炉密相区进行炉内一次脱硫；在炉膛出口进行基于SNCR的一次脱硝；经炉内一次脱硫和一次脱硝后的烟气进行除尘后再升温进行基于SCR的二次脱硝；经二次脱硝后的烟气送入脱硫系统进行二次脱硫；本发明还提供了相应的系统，采用SNCR+SCR方式联合脱硝，同时采用炉内+炉外方式脱硫，通过燃烧优化技术+环保系统参数精确控制，使得NOx、SO2排放达到《火电厂大气污染物排放标准》GB13223-2011中重点地区燃气轮机组的排放标准，具有脱硝效率高、脱硫效率高、系统可靠性高、工况适应性强、NOx、SO2排放可控性好、运行周期长、运行费用低等优点。
A clean discharge method for fluidized bed boilers, performing primary desulfurization in the furnace in the dense phase area of the fluidized bed boiler; performing primary denitrification based on SNCR at the outlet of the furnace; After dedusting, the temperature is raised to carry out secondary denitrification based on SCR; the flue gas after secondary denitrification is sent to the desulfurization system for secondary desulfurization; + Desulfurization outside the furnace, through combustion optimization technology + precise control of environmental protection system parameters, NO x and SO 2 emissions can reach the emission standards of gas turbine units in key areas in the "Emission Standards of Air Pollutants for Thermal Power Plants" GB13223-2011, with high denitrification efficiency , high desulfurization efficiency, high system reliability, strong adaptability to working conditions, good controllability of NO x and SO 2 emissions, long operating cycle, and low operating costs.
Description
技术领域technical field
本发明属于锅炉环保技术领域，特别涉及一种用于流化床锅炉的洁净排放系统及方法。The invention belongs to the technical field of boiler environmental protection, and in particular relates to a clean discharge system and method for a fluidized bed boiler.
背景技术Background technique
循环流化床锅炉技术是近十几年来迅速发展的一项高效低污染清洁燃烧枝术，具有燃料适应性广、燃烧效率高、高效脱硫、氮氧化物(NOX)排放低、燃烧强度高、炉膛截面积小、负荷调节范围大、负荷调节快、易于实现灰渣综合利用、燃料预处理系统简单、给煤点少等优点。因此这项技术在电站锅炉、工业锅炉和废弃物处理利用等领域均得到了广泛的商业应用。Circulating fluidized bed boiler technology is a high-efficiency, low-pollution and clean combustion technology that has developed rapidly in the past ten years. It has wide fuel adaptability, high combustion efficiency, high-efficiency desulfurization, low nitrogen oxide (NO X ) emissions, and high combustion intensity. , Small cross-sectional area of the furnace, large load adjustment range, fast load adjustment, easy to realize comprehensive utilization of ash and slag, simple fuel pretreatment system, few coal feeding points, etc. Therefore, this technology has been widely used commercially in the fields of power station boilers, industrial boilers and waste treatment and utilization.
运行经验表明，循环流化床锅炉的NOX排放值基本在400mg/m3以下。循环流化床锅炉NOX排放低是由于以下两个原因：一是低温燃烧，此时空气中的氮一般不会生成NOX；二是分段燃烧，抑制燃料中的氮转化为NOX，并使部分已生成的NOX得到还原。Operating experience shows that the NOx emission value of circulating fluidized bed boilers is basically below 400mg/m 3 . The low emission of NO X from circulating fluidized bed boilers is due to the following two reasons: one is low-temperature combustion, at which time the nitrogen in the air generally does not generate NO X ; And make part of the NO X that has been generated be reduced.
《火电厂大气污染排放标准》(GB13223-2003)中对SO2和NOX的排放限值分别为400mg/m3、450mg/m3。对于循环流化床锅炉，仅需进行炉内脱硫即可使SO2排放、NOX排放达标，故原有循环流化床锅炉机组基本不设置脱硝装置。《火电厂大气污染排放标准》(GB13223-2011)实施后，对SO2和NOX的排放限值均降为100mg/m3，导致现有设备条件基本无法满足环保要求。The emission limits for SO 2 and NO X in the "Emission Standards for Air Pollution from Thermal Power Plants" (GB13223-2003) are 400mg/m 3 and 450mg/m 3 , respectively. For circulating fluidized bed boilers, only desulfurization in the furnace is required to make SO2 emissions and NOx emissions meet the standards, so the original circulating fluidized bed boiler units basically do not have denitrification devices. After the implementation of the "Emission Standards for Air Pollution from Thermal Power Plants" (GB13223-2011), the emission limits for SO 2 and NO X were both reduced to 100mg/m 3 , resulting in the existing equipment conditions basically failing to meet environmental protection requirements.
目前应用于锅炉的脱硝技术主要分为燃烧控制技术和烟气脱硝技术。燃烧控制技术包括：CFB锅炉燃烧技术、空气分级燃烧、燃料分级燃烧、烟气再循环、低氮燃烧器技术、燃烧优化；烟气脱硝技术主要包括：SCR(选择性催化还原技术)、SNCR(选择性非催化还原法)、SNCR+SCR。目前应用于循环流化床锅炉的主要是燃烧控制技术。The denitrification technology currently applied to boilers is mainly divided into combustion control technology and flue gas denitrification technology. Combustion control technology includes: CFB boiler combustion technology, air staged combustion, fuel staged combustion, flue gas recirculation, low nitrogen burner technology, combustion optimization; flue gas denitration technology mainly includes: SCR (selective catalytic reduction technology), SNCR ( Selective non-catalytic reduction method), SNCR+SCR. At present, the combustion control technology is mainly used in circulating fluidized bed boilers.
SCR的优点是：脱硝效率高(70～90％)、技术成熟，国内应用多；缺点是：投资成本高(需要催化剂、造价为SNCR的3倍以上)、运行成本较高(还原剂、催化剂)、安装方式对锅炉结构改变大、尾部易沾污、腐蚀、适用于新建煤粉机组。The advantages of SCR are: high denitrification efficiency (70-90%), mature technology, and many domestic applications; the disadvantages are: high investment cost (requires catalyst, cost is more than 3 times that of SNCR), high operating cost (reductant, catalyst ), the installation method changes the boiler structure greatly, the tail is easy to be stained and corroded, and is suitable for new pulverized coal units.
SNCR的优点是：占地面积小(布置在锅炉本体上)、投资成本低(造价为SCR的1/4～1/3)、运行成本较低(0.003～0.004元/kWh)、安装及操作较易、技术成熟；适应参数、负荷、煤质变化快；有助于降低平均成本、不催化增加三氧化硫(SO3)、不造成尾部受热面、空气预热器的堵塞或腐蚀；特别适用于CFB机组及老机组脱硝改造；缺点是：脱硝效率不够高、氨逃逸量较SCR稍高。The advantages of SNCR are: small footprint (arranged on the boiler body), low investment cost (1/4-1/3 of SCR), low operating cost (0.003-0.004 yuan/kWh), installation and operation Relatively easy, mature technology; adapt to parameters, loads, and coal quality changes quickly; help reduce average cost, do not catalyze the increase of sulfur trioxide (SO 3 ), and do not cause blockage or corrosion of the rear heating surface and air preheater; especially It is suitable for the denitrification transformation of CFB units and old units; the disadvantages are: the denitrification efficiency is not high enough, and the amount of ammonia escape is slightly higher than that of SCR.
SNCR+SCR的特点：脱硝效率高(40～80％)、投资成本略低、运行成本略低(还原剂、少量催化剂)、氨逃逸量低、可大幅减少SCR的反应容积。逃逸的氨会随烟气流向下游的SCR系统，使其利用率反应率更为完全。还原剂可使用尿素代替较危险的液氨。缺点是：流化床锅炉应用经验较少，同时也存在SCR催化剂寿命短等问题。The characteristics of SNCR+SCR: high denitrification efficiency (40-80%), slightly lower investment cost, slightly lower operating cost (reductant, small amount of catalyst), low ammonia escape, and can greatly reduce the reaction volume of SCR. The escaped ammonia will flow to the downstream SCR system with the flue gas, making its utilization rate more complete. The reducing agent can use urea to replace the more dangerous liquid ammonia. The disadvantages are: less experience in the application of fluidized bed boilers, and there are also problems such as short life of SCR catalysts.
目前应用于流化床锅炉的脱硫技术主要是炉内脱硫，烟气脱硫主要应用于煤粉炉。流化床锅炉通过炉内添加脱硫剂(石灰石、电石渣等)可将SO2排放值控制到较低水平，但在新的环保标准下，现有炉内脱硫装置存在出力不够、经济性差、脱硫难以达标等问题。The desulfurization technology currently applied to fluidized bed boilers is mainly in-furnace desulfurization, and flue gas desulfurization is mainly used in pulverized coal boilers. Fluidized bed boilers can control SO 2 emissions to a low level by adding desulfurizers (limestone, carbide slag, etc.) Desulfurization is difficult to meet the standard and other issues.
发明内容Contents of the invention
为了克服上述现有技术的缺点，本发明的目的在于提供一种用于流化床锅炉的洁净排放系统及方法，该系统具有本系统具有脱硝效率高、脱硫效率高、系统可靠性高、工况适应性强、NOx、SO2排放可控性好、运行周期长、运行费用低等优点，可使现有流化床锅炉满足《火电厂大气污染排放标准》(GB13223-2011)。In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a clean discharge system and method for fluidized bed boilers. The system has the advantages of high denitrification efficiency, high desulfurization efficiency, high system reliability, and The advantages of strong environmental adaptability, good controllability of NO x and SO 2 emissions, long operation period and low operation cost can make the existing fluidized bed boiler meet the "Emission Standard of Air Pollution for Thermal Power Plants" (GB13223-2011).
为了实现上述目的，本发明采用的技术方案是：In order to achieve the above object, the technical scheme adopted in the present invention is:
一种用于流化床锅炉的洁净排放方法，其中：A clean discharge method for a fluidized bed boiler wherein:
在流化床锅炉密相区进行炉内一次脱硫；In-furnace desulfurization in the dense-phase area of the fluidized bed boiler;
在炉膛出口进行基于SNCR的一次脱硝；Perform primary denitrification based on SNCR at the furnace outlet;
经炉内一次脱硫和一次脱硝后的烟气进行除尘后再升温进行基于SCR的二次脱硝；After the first desulfurization and first denitrification in the furnace, the flue gas is dedusted and then the temperature is raised for the second denitrification based on SCR;
经二次脱硝后的烟气送入脱硫系统进行二次脱硫。The flue gas after secondary denitrification is sent to the desulfurization system for secondary desulfurization.
本发明还提供了一种用于流化床锅炉的洁净排放系统，包括布置于流化床锅炉密相区的炉内脱硫装置14和布置于炉膛13出口的SNCR装置12，其特征在于，所述SNCR装置12出口连接分离器11，出分离器11的烟气依次经过过热器10和省煤器9后分为两路，一路直接接入SCR装置5并在管路上设置有烟气挡板一8，另一路经空气预热器16和除尘器18后接入SCR装置5，且SCR装置5与除尘器18的连接管路上设置有烟气挡板二19，SCR装置5的烟气出口与脱硫系统1的烟气入口相连接且在连接管路上设置有引风机22和增压风机25，SCR装置5与引风机22的连接管路上设置有烟气挡板三21，引风机22与增压风机25的连接管路上设置有烟气挡板四24，出脱硫系统1的烟气排至烟囱，另外设置洁净烟气发生器7，洁净烟气发生器7的出口分为两路，一路接至SCR装置入口并设置烟气挡板七6，一路接至脱硫系统1的烟气出口并设置烟气挡板六2。The present invention also provides a clean discharge system for a fluidized bed boiler, which includes an in-furnace desulfurization device 14 arranged in the dense phase area of the fluidized bed boiler and an SNCR device 12 arranged at the outlet of the furnace 13, characterized in that the The outlet of the SNCR device 12 is connected to the separator 11, and the flue gas exiting the separator 11 passes through the superheater 10 and the economizer 9 in turn and is divided into two paths, one path is directly connected to the SCR device 5 and a flue gas baffle is installed on the pipeline One 8, the other path is connected to the SCR device 5 after passing through the air preheater 16 and the dust collector 18, and the connecting pipeline between the SCR device 5 and the dust collector 18 is provided with a flue gas baffle 2 19, and the flue gas outlet of the SCR device 5 It is connected with the flue gas inlet of the desulfurization system 1 and is provided with an induced draft fan 22 and a booster fan 25 on the connecting pipeline, and a flue gas baffle 3 21 is arranged on the connecting pipeline between the SCR device 5 and the induced draft fan 22, and the induced draft fan 22 and the A flue gas baffle 24 is arranged on the connecting pipeline of the booster fan 25, and the flue gas exiting the desulfurization system 1 is discharged to the chimney. In addition, a clean flue gas generator 7 is installed, and the outlet of the clean flue gas generator 7 is divided into two paths. One way is connected to the entrance of the SCR device and the flue gas baffle 7 6 is set, and the other way is connected to the flue gas outlet of the desulfurization system 1 and the flue gas baffle 6 2 is set.
所述炉膛13底部连接有风室15，锅炉尾部烟道连接有为锅炉提供配风的送风机17。The bottom of the furnace 13 is connected with an air chamber 15, and the tail flue of the boiler is connected with a blower 17 for providing air distribution for the boiler.
所述SCR装置5并联设置有SCR旁路20，SCR旁路20连接在烟气挡板二19和烟气挡板三21之间，所述SCR旁路20、烟气挡板二19和烟气挡板三用于实现SCR装置5的投退切换；所述脱硫系统1并联设置有脱硫系统旁路23，脱硫系统旁路23设置在烟气挡板四24和烟气挡板五3之间，所述脱硫系统旁路23、烟气挡板四24和烟气挡板五3用于实现脱硫系统1的投退切换。The SCR device 5 is provided with an SCR bypass 20 in parallel, the SCR bypass 20 is connected between the second smoke baffle 19 and the third smoke baffle 21, the SCR bypass 20, the second smoke baffle 19 and the smoke Gas baffle 3 is used to switch between switching on and off of SCR device 5; said desulfurization system 1 is provided with desulfurization system bypass 23 in parallel, and desulfurization system bypass 23 is arranged between flue gas baffle 4 24 and flue gas baffle 5 3 During the period, the desulfurization system bypass 23, the flue gas baffle 4 24 and the flue gas baffle 5 3 are used to switch the desulfurization system 1 between operation and withdrawal.
所述SNCR装置12布置在炉膛13出口的800～1050℃区域。The SNCR device 12 is arranged in the 800-1050°C region at the outlet of the furnace 13 .
所述炉内脱硫装置14布置在炉膛13的下部密相区。The furnace desulfurization device 14 is arranged in the lower dense phase area of the furnace 13 .
所述洁净烟气发生器7采用天然气或燃油作为燃料，用于提升SCR装置5的入口烟气温度，为中高温催化剂提供工作环境；以及用于提升脱硫系统1的出口烟气温度，以保证烟气的扩散能力。The clean flue gas generator 7 uses natural gas or fuel oil as fuel, and is used to increase the inlet flue gas temperature of the SCR device 5 to provide a working environment for the medium-high temperature catalyst; and is used to increase the outlet flue gas temperature of the desulfurization system 1 to ensure Diffusion capacity of smoke.
与现有技术相比，本发明的有益效果是：Compared with prior art, the beneficial effect of the present invention is:
1)本系统所述SCR装置布置在除尘器的出口区域，烟尘较少，催化剂工作环境较好，使用周期长。1) The SCR device described in this system is arranged in the outlet area of the dust collector, with less smoke and dust, better catalyst working environment and long service life.
2)本系统设置的洁净烟气发生器可以提升SCR装置入口烟气温度，为中高温催化剂提供工作环境；也可以提升脱硫系统出口烟气温度，以保证烟气有较高的扩散能力。2) The clean flue gas generator set in this system can increase the flue gas temperature at the inlet of the SCR device to provide a working environment for the medium and high temperature catalysts; it can also increase the flue gas temperature at the outlet of the desulfurization system to ensure a high diffusion capacity of the flue gas.
3)本系统采用SNCR+SCR：脱硝效率高(40～80％)、投资成本略低、运行成本略低(还原剂、少量催化剂)、氨逃逸量低、可大幅减少SCR的反应容积。逃逸的氨会随烟气流向下游的SCR系统，使其利用率反应率更为完全，还原剂可使用尿素代替较危险的液氨。3) The system adopts SNCR+SCR: high denitrification efficiency (40-80%), slightly lower investment cost, slightly lower operating cost (reductant, small amount of catalyst), low ammonia escape, and can greatly reduce the reaction volume of SCR. The escaped ammonia will flow to the downstream SCR system with the flue gas, making its utilization rate more complete, and the reducing agent can use urea to replace the more dangerous liquid ammonia.
4)本系统采用炉内脱硫与炉外脱硫相结合方式，现有脱硫系统仍可使用，同时投用时，炉外脱硫装置运行费用较低，SO2排放可得到有效控制。4) This system adopts the combination of in-furnace desulfurization and out-of-furnace desulfurization. The existing desulfurization system can still be used. When put into use at the same time, the operating cost of the out-of-furnace desulfurization device is lower, and SO 2 emissions can be effectively controlled.
综上所述，本系统具有本系统具有脱硝效率高、脱硫效率高、系统可靠性高、工况适应性强、NOx、SO2排放可控性好、运行周期长、运行费用低等优点。In summary, this system has the advantages of high denitrification efficiency, high desulfurization efficiency, high system reliability, strong adaptability to working conditions, good controllability of NO x and SO 2 emissions, long operating cycle, and low operating costs. .
附图说明Description of drawings
图1是本发明用于流化床锅炉的洁净排放系统的结构示意图。Fig. 1 is a structural schematic diagram of a clean exhaust system for a fluidized bed boiler according to the present invention.
具体实施方式Detailed ways
下面结合附图和实施例详细说明本发明的实施方式。The implementation of the present invention will be described in detail below in conjunction with the drawings and examples.
本发明一种用于流化床锅炉的洁净排放方法，主要通过如下工艺环节实现：A clean discharge method for a fluidized bed boiler according to the present invention is mainly realized through the following process steps:
在流化床锅炉密相区进行炉内一次脱硫；In-furnace desulfurization in the dense-phase area of the fluidized bed boiler;
在炉膛出口进行基于SNCR的一次脱硝；Perform primary denitrification based on SNCR at the furnace outlet;
经炉内一次脱硫和一次脱硝后的烟气进行除尘后再升温进行基于SCR的二次脱硝；After the first desulfurization and first denitrification in the furnace, the flue gas is dedusted and then the temperature is raised for the second denitrification based on SCR;
经二次脱硝后的烟气送入脱硫系统进行二次脱硫。The flue gas after secondary denitrification is sent to the desulfurization system for secondary desulfurization.
为了实现上述方法，并有效适应各种不同的实际工况，本发明还提供了一种用于流化床锅炉的洁净排放系统，如图1所示，包括布置于流化床锅炉密相区的炉内脱硫装置14，炉内脱硫装置14位于炉膛13的下部，炉膛13底部连接有风室15，送风机17供风通过布置在尾部烟道内的空气预热器16预热后送至风室15。SNCR装置12布置在炉膛13出口的800～1050℃区域。In order to realize the above method and effectively adapt to various actual working conditions, the present invention also provides a clean discharge system for a fluidized bed boiler, as shown in Figure 1, including The desulfurization device 14 in the furnace is located at the lower part of the furnace 13, the bottom of the furnace 13 is connected with the air chamber 15, and the air supplied by the blower 17 is preheated by the air preheater 16 arranged in the tail flue and then sent to the air chamber 15. The SNCR device 12 is arranged in the 800-1050°C area at the outlet of the furnace 13 .
SNCR装置12的烟气出口连接分离器11，出分离器11的烟气依次经过过热器10和省煤器9后分为两路，一路直接接入SCR装置5并在管路上设置有烟气挡板一8，烟气挡板一8用于调节SCR装置5的入口烟温。另一路经空气预热器16和除尘器18后接入SCR装置5，且SCR装置5与除尘器18的连接管路上设置有烟气挡板二19，SCR装置5的烟气出口与脱硫系统1的烟气入口相连接且在连接管路上设置有引风机22和增压风机25，SCR装置5与引风机22的连接管路上设置有烟气挡板三21，引风机22与增压风机25的连接管路上设置有烟气挡板四24。The flue gas outlet of the SNCR device 12 is connected to the separator 11, and the flue gas exiting the separator 11 is divided into two paths after passing through the superheater 10 and the economizer 9 in sequence, one path is directly connected to the SCR device 5 and the flue gas is installed on the pipeline. The first baffle 8 and the first flue gas baffle 8 are used to adjust the inlet smoke temperature of the SCR device 5 . The other path passes through the air preheater 16 and the dust collector 18 and then connects to the SCR device 5, and the connecting pipeline between the SCR device 5 and the dust collector 18 is provided with a flue gas baffle 2 19, and the flue gas outlet of the SCR device 5 is connected to the desulfurization system. The flue gas inlet of 1 is connected and the induced draft fan 22 and the booster fan 25 are arranged on the connecting pipeline, the smoke baffle 3 21 is arranged on the connecting pipeline between the SCR device 5 and the induced draft fan 22, the induced draft fan 22 and the booster fan The connecting pipeline of 25 is provided with flue gas damper 24.
为适应不同工况，SCR装置5并联设置有SCR旁路20，SCR旁路20连接在烟气挡板二19和烟气挡板三21之间，SCR旁路20、烟气挡板二19和烟气挡板三用于实现SCR装置5的投退切换；脱硫系统1并联设置有脱硫系统旁路23，脱硫系统旁路23设置在烟气挡板四24和烟气挡板五3之间，脱硫系统旁路23、烟气挡板四24和烟气挡板五3用于实现脱硫系统1的投退切换。In order to adapt to different working conditions, the SCR device 5 is provided with an SCR bypass 20 in parallel. The SCR bypass 20 is connected between the smoke baffle 2 19 and the smoke baffle 3 21. and flue gas baffle 3 are used to switch between switching on and off of SCR device 5; desulfurization system 1 is provided with desulfurization system bypass 23 in parallel, and desulfurization system bypass 23 is set between flue gas baffle 4 24 and flue gas baffle 5 3 During the period, the desulfurization system bypass 23, the flue gas baffle 4 24 and the flue gas baffle 5 3 are used to realize the switching of the desulfurization system 1 on and off.
出脱硫系统1的烟气排至烟囱；另外设置洁净烟气发生器7，出口分为两路，一路接至SCR装置入口并设置烟气挡板七6，一路接至脱硫系统出口并设置烟气挡板六2。洁净烟气发生器7采用天然气或燃油作为燃料，用于提升SCR装置5的入口烟气温度，为中高温催化剂提供工作环境；以及用于提升脱硫系统1的出口烟气温度，以保证烟气的扩散能力。The flue gas exiting the desulfurization system 1 is discharged to the chimney; in addition, a clean flue gas generator 7 is installed, and the outlet is divided into two paths, one path is connected to the entrance of the SCR device and a flue gas baffle 7 6 is set, and the other path is connected to the exit of the desulfurization system and a flue gas baffle is set. Gas baffle six 2. The clean flue gas generator 7 uses natural gas or fuel oil as fuel to increase the flue gas temperature at the inlet of the SCR device 5 to provide a working environment for the medium-high temperature catalyst; and to increase the flue gas temperature at the outlet of the desulfurization system 1 to ensure that the flue gas the ability to spread.
本发明的工作原理是：The working principle of the present invention is:
燃料在循环流化床锅炉中燃烧，脱硫剂由锅炉密相区炉内的脱硫装置14给入，进行炉内一次脱硫；燃烧烟气流至炉膛13的出口时，由SNCR装置12进行一次脱硝，脱去大部分NOX；经过炉内脱硫和一次脱硝后烟气经过热器10、省煤器9、空气预热器16、除尘器18到达SCR装置5，烟气在SCR装置5中进行二次脱硝，达到NOX达标工况；之后烟气进入脱硫系统1进行二次脱硫，达到SO2达标工况；洁净烟气最终由烟囱4排至大气。The fuel is combusted in the circulating fluidized bed boiler, and the desulfurizer is supplied by the desulfurization device 14 in the dense-phase zone of the boiler to perform primary desulfurization in the furnace; when the combustion flue gas flows to the outlet of the furnace 13, the SNCR device 12 performs primary denitrification , to remove most of the NOx ; after furnace desulfurization and primary denitrification, the flue gas passes through the heater 10, the economizer 9, the air preheater 16, and the dust collector 18 to reach the SCR device 5, and the flue gas is carried out in the SCR device 5 Secondary denitrification, reaching the NO X standard working condition; after that, the flue gas enters the desulfurization system 1 for secondary desulfurization, reaching the SO 2 standard working condition; the clean flue gas is finally discharged to the atmosphere through the chimney 4.
由于本系统SCR装置5布置在除尘器18出口区域，烟尘较少，催化剂工作环境较好，故而催化剂使用周期长，运行成本降低；洁净烟气发生器7可以提升SCR装置5入口烟气温度，为中高温催化剂提供工作环境；也可以提升脱硫系统1出口烟气温度，以保证烟气有较高的扩散能力；采用SNCR+SCR组合脱硝方式，脱硝效率高(40～80％)、投资成本略低、运行成本略低(还原剂、少量催化剂)、氨逃逸量低、可大幅减少SCR的反应容积。逃逸的氨会随烟气流向下游的SCR系统，使其利用率反应率更为完全，还原剂可使用尿素代替较危险的液氨；采用炉内脱硫与炉外脱硫相结合方式，现有脱硫系统仍可使用，同时投用时，炉外脱硫装置运行费用较低，SO2排放可得到有效控制。Since the SCR device 5 of this system is arranged in the outlet area of the dust collector 18, there is less smoke and dust, and the working environment of the catalyst is better, so the service life of the catalyst is long and the operating cost is reduced; the clean flue gas generator 7 can increase the flue gas temperature at the entrance of the SCR device 5, Provide a working environment for medium and high temperature catalysts; it can also increase the flue gas temperature at the outlet of the desulfurization system 1 to ensure a high diffusion capacity of the flue gas; adopt the SNCR+SCR combined denitrification method, with high denitrification efficiency (40-80%) and low investment costs Slightly lower, slightly lower operating costs (reducing agent, a small amount of catalyst), low ammonia slip, can greatly reduce the reaction volume of the SCR. The escaped ammonia will flow to the downstream SCR system with the flue gas flow to make its utilization rate more complete. The reductant can use urea instead of the more dangerous liquid ammonia; the combination of in-furnace desulfurization and out-of-furnace desulfurization is adopted, and the existing desulfurization The system can still be used, and when it is put into use at the same time, the operation cost of the desulfurization device outside the furnace is low, and the SO2 emission can be effectively controlled.
正常工况下，关闭SCR旁路挡板20、脱硫系统旁路23、烟气挡板七6、烟气挡板六2，打开烟气挡板一8、烟气挡板二19、烟气挡板三21、烟气挡板四24、烟气挡板五3，通过烟气挡板一8调节SCR入口烟气温度，如使用低温催化剂，甚至可关闭烟气挡板一8；Under normal working conditions, close SCR bypass damper 20, desulfurization system bypass 23, flue gas damper 7, flue gas damper 6, and open flue gas damper 1 8, flue gas damper 2 19, flue gas Baffle 3 21, flue gas baffle 4 24, flue gas baffle 5 3, the flue gas temperature at the SCR inlet can be adjusted through the flue gas baffle 18, and the flue gas baffle 18 can even be closed if a low-temperature catalyst is used;
烟气含尘量大或SO2排放要求更高时，关闭SCR旁路挡板20、脱硫系统旁路23、烟气挡板一8，打开烟气挡板七6、烟气挡板六2、烟气挡板二19、烟气挡板三21、烟气挡板四24、烟气挡板五3，通过烟气挡板七6调节SCR入口烟气温度；When the dust content of the flue gas is large or the SO2 emission requirement is higher, close the SCR bypass baffle 20, the desulfurization system bypass 23, the flue gas baffle 1, and open the flue gas baffle 7 6 and the flue gas baffle 6 2 , flue gas baffle two 19, flue gas baffle three 21, flue gas baffle four 24, flue gas baffle five 3, adjust the SCR inlet flue gas temperature through the flue gas baffle seven 6;
炉内脱硫、SNCR脱硝即可达到排放指标时，打开SCR旁路挡板20、脱硫系统旁路23，关闭烟气挡板二19、烟气挡板三21、烟气挡板四24、烟气挡板五3，达标烟气直接通过烟囱排放；如经炉内脱硫、SNCR后仅脱硫或脱硝达标，则相应切除脱硫系统1或SCR5运行，以节约能源；When the desulfurization in the furnace and SNCR denitrification can reach the emission target, open the SCR bypass baffle 20, the desulfurization system bypass 23, close the flue gas baffle 2 19, the flue gas baffle 3 21, the flue gas baffle 4 24, the smoke baffle Gas baffle five 3, the flue gas that reaches the standard is directly discharged through the chimney; if only desulfurization or denitrification reaches the standard after desulfurization in the furnace and SNCR, the desulfurization system 1 or SCR5 will be cut off accordingly to save energy;
通过调整炉内脱硫、SNCR脱硝效率，本系统可方便调节炉内脱硫、脱硝与炉外脱硫、脱硝比例，以达到整套系统综合能效最高的最优工况。By adjusting the efficiency of desulfurization and SNCR denitrification in the furnace, this system can easily adjust the ratio of desulfurization and denitration in the furnace to that of desulfurization and denitrification outside the furnace, so as to achieve the optimal working condition with the highest comprehensive energy efficiency of the whole system.
因而，本系统具有脱硝效率高、脱硫效率高、系统可靠性高、工况适应性强、NOX、SO2排放可控性好、运行周期长、运行费用低等优点。Therefore, this system has the advantages of high denitrification efficiency, high desulfurization efficiency, high system reliability, strong adaptability to working conditions, good controllability of NO x and SO 2 emissions, long operating period, and low operating costs.
以上对本发明的一个实例进行了详细说明，但内容仅为本发明的较佳实施例，不能认为用于限定本发明的实施范围。凡依本发明申请范围所做出的变化与改进等，均应仍归属于本发明的保护涵盖范围之内。An example of the present invention has been described in detail above, but the content is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All changes and improvements made according to the application scope of the present invention shall still belong to the scope of protection of the present invention.
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