活性焦烟气净化反应器研究进展

Research progress of activated coke flue gas purification reactor

活性焦干法烟气净化技术具有耗水量少、无二次污染以及吸附剂可循环利用的应用优势,发展前景广阔。作为工艺的核心,反应器研究成为了制约该项技术发展的关键。各行业排放烟气特点不同且污染物排放限值也有所差异,根据烟气特点精准选择反应器类型并对反应器结构进行优化,是提高系统烟气净化效率的有效手段。介绍了目前活性焦烟气净化领域所应用的各类反应器的优缺点及适用范围,论述了反应器内不同类型内构件对气固两相运动状态的影响,最后提出了未来活性焦烟气净化反应器研究及优化的技术方向。反应器床型方面,总结了固定床反应器、移动床反应器、流化床反应器3类反应器的技术优势以及存在的短板。其中,固定床反应器结构简单,通常被应用于活性焦单独脱硫工艺中,烟气处理量小时灵活性较强,随烟气处理量增大,其净化效果降低且需多个反应器并联操作,占地面积大,投入成本高;流化床反应器气固通量大,自动性高,传质传热性能优越,但对内部颗粒磨损作用强,不适合颗粒活性焦,对粉状活性焦有较好的适用性;移动床反应器目前在活性焦烟气净化领域应用最为广泛,具有连续性强、烟气处理量大、对颗粒机械强度要求不高的优点,但其内部结构复杂,物料容易出现异常流动。反应器内构件方面,重点讨论了烟气导流构件、喷氨混合构件、下料构件对系统烟气净化效率的影响。针对反应器内气相流动紊乱的情况,可通过添加导流板或整流层的方式提高反应器内烟气均布性;为了提高喷氨均匀性可在喷氨区设置喷氨构件,提高系统的脱硝效率,较为常见的喷氨构件有静态混合器、喷氨格栅以及涡流构件等,其中静态混合器调控精准,但成本较高且处理能力有限,喷氨格栅能够实现分区控制但易出现管路堵塞问题,涡流构件改造成本低但调控灵活性较差,在工业生产中需根据喷氨量及烟气排放指标灵活选择喷氨构件;为防止固体物料在反应器内运动过程中出现“漏斗流”等异常流动,可在反应器内部添加下料构件,下料构件可有效改善固体物料在反应器内的流动状态。添加内构件后反应器内气固接触增强,系统净化效率明显提升,改造成本降低。最后,明确了未来活性焦烟气净化反应器将向着创新反应器床型,增强行业匹配性,优化反应器结构,降低运行及维护成本的方向发展。

Activated coke dry method flue gas purification technology has the advantages of low water consumption,no secondary pollution and recyclable use of adsorbent,and has broad development prospect.As the core of the process,the research of reactor has become the key to restrict the development of this technology.The flue gas emission characteristics and the pollutant emission limits of different industries are different.Accurately selecting the reactor type and optimizing the reactor structure according to the flue gas characteristics is an effective means to improve the system flue gas purification efficiency.In this paper,the advantages and disadvantages of various types of reactors currently used in the field of activated coke flue gas purification and its scope of application were introduced,the effects of different types of internal components on the gas-solid two-phase motion state in the reactor were discussed,and the future research direction of activated coke and the optimization of flue gas purification reactor were finally proposed.In terms of reactor bed type,the technical advantages and shortcomings of three types of reactors,including fixed bed reactors,moving bed reactors and fluidized bed reactors,were summarized.Among them,the structure of fixed-bed reactor is simple and usually used in the active coke desulfurization process.When the flue gas treatment volume is small,the flexibility is strong.As the flue gas treatment volume increases,its purification effect decreases and multiple reactors are required to operate in parallel,which has large area,high input cost;fluidized bed reactor has the advantages of large gas-solid flux,high automation,excellent mass and heat transfer performance,but it is not suitable for granular active coke due to strong internal particle wear,and has good applicability for powdery activity coke;the moving bed reactor is currently the most widely used in the field of active coke flue gas purification,with the advantages of strong continuity,large flue gas treatment capacity,and low requirements for particle mechanical strength,but its internal structure is complex,and materials are prone to abnormal flow.With regard to the internal components of the reactor,the effects of flue gas guide components,ammonia injection mixing components,and discharge components on the system's flue gas purification efficiency were discussed.In view of the turbulent gas flow in the reactor,the uniformity of flue gas in the reactor can be improved by adding a deflector or a rectifying layer;in order to improve the uniformity of ammonia injection,ammonia injection components can be provided in the ammonia injection area to improve the denitrification efficiency of the system,the more common ammonia injection components include static mixers,ammonia injection grids,and vortex components.Among them,static mixer is precisely controlled,but the cost is high and the processing capacity is limited.The ammonia injection grid can achieve zone control but is easy to appear the problem of pipeline clogging.The cost of vortex component reconstruction is low,but the control flexibility is poor.In industrial production,it is necessary to flexibly select ammonia injection components according to the amount of ammonia injection and flue gas emission indicators;in order to prevent solid materials from appearing"funnel flow"and other abnormal flows during the movement of the reactor,a discharge member can be added inside the reactor,which can effectively improve the flow state of solid materials in the reactor.After adding internal components,the gas-solid contact in the reactor is enhanced,the system purification efficiency is significantly improved,and the cost of transformation is reduced.Finally,it was clarified that the future activated coke flue gas purification reactor will be developed in the direction of innovative reactor bed type,enhancing industry matching,optimizing reactor structure,and reducing operation and maintenance costs.