Thermal and Catalytic Incinerators for the Control of VOCs

Abstract

The emission of Volatile Organic Compounds (VOCs) is attracting increasing concern both from the public and by government agencies. Among the many available control technologies for the treatment of VOC containing waste streams, incineration offers an ultimate disposal strategy rather than a means for collecting or concentrating the offending compounds. This paper describes the major, commercially available thermal and catalytic incinerator systems that are designed to treat dilute, VOC containing gas streams. Qualitative guidelines are presented whereby the technologies can be compared. In addition, an example waste stream is used to illustrate a simplified procedure for calculating the material and energy balances for each of the incinerators. The resulting parameters will be used in a companion paper to estimate the capital and operating costs associated with each design. In this manner, a first estimate can be obtained of the costs of cleaning a waste stream containing low levels of VOCs.     

The Cost Estimation of Thermal and Catalytic Incinerators for the Control of VOCs

In an earlier paper, major commercially available incinerator technologies designed to treat dilute waste gas streams containing volatile organic compounds (VOCs) were described in a qualitative comparison. In addition, a simplified procedure was outlined through which important sizing parameters could be calculated given certain information about the waste gas. This paper describes the use of these parameters in developing a study (±30percent) cost estimate for the total capital investment and the total annual costs incurred in treating a waste stream of volatile organic compounds (VOCs). An illustrative problem used in the former paper is completed here in order to contrast some of the economic differences between thermal and catalytic incinerator systems.     

Potential of biofiltration for VOCs emission control and safety aspects

Directive 99/13/EC on the emission of Volatile Organic Compounds (VOCs) is impacting on several industries in Italy, as well in other EU countries. Many small enterprises have to invest in new control systems and need to be helped to choose an appropriate and safe technology. As VOCs are highly flammable compounds, high concentrations in emission flows can pose a fire and explosion hazard if control systems are not properly designed and proper procedures are not implemented. Biofiltration may be considered as a suitable solution for VOC emissions control, as investment and operation costs are lower and performances are comparable with other abatement systems and comply with permit requirements. Furthermore, mild exercise conditions allow safer operations.     

微波催化燃烧技术处理印刷包装行业VOCs

微波催化燃烧技术将微波辐照与吸波型催化剂相结合,可用于对挥发性有机化合物(VOCs)进行催化燃烧处置。研制了Pt/CuMnCeO_x/堇青石和Pt/CuMnCeO_x/纳米陶瓷整体式蜂窝状催化剂,并开发了微波催化燃烧VOCs的装置,将其应用于印刷包装行业的VOCs治理。通过操作条件的优化,考察了微波催化燃烧技术对VOCs的实际处理效果。同时,对催化剂表面形貌、比表面积和晶体结构等进行了测试分析。结果表明：Mn₃O₄/Mn₂O₃、CeO₂/Ce₂O₃、CuMn₂O₄和PtO等尖晶石的存在降低了反应温度、提高了储氧释氧能力和催化剂活性;催化剂的介孔结构和较大的比表面积有利于VOCs在孔隙内部的扩散,并可延长VOCs在催化剂上的停留时间。在催化剂床层体积330 L、微波功率13.6 kW、进气质量浓度1 520 mg·m^-3和进气量440 m³·h⁻¹的条件下,床层温度可达到420 ℃,此时催化剂床层温度及VOCs去除率保持稳定。当进气质量浓度分别为约4 500 mg·m⁻³和2 800 mg·m⁻³时,VOCs的去除率分别为90%和96%。考察燃烧热量发现,大气量的VOCs在催化剂表面的停留时间短且带走热量多,从而导致VOCs去除率下降;高浓度VOCs在燃烧时会因释放出更多热量,从而提高床层温度和VOCs去除率。在确保催化剂表面活性位点充足的条件下,微波催化燃烧工艺适合处理中高浓度的印刷包装行业VOCs。同时,利用VOCs燃烧释放的热量来保持床层高温,还可达到节能降耗的目的。本研究可为印刷包装行业的VOCs治理提供参考。     

Thermal behavior of PCDD/PCDF in fly ash from municipal incinerators

The effect of thermal treatment of fly ash on the behaviour of PCDD/PCDF was studied in the range between 120 and 600° C. Annealing at 300° C (2 hrs) resulted in an increase of PCDD/PCDF concentration by a factor of 10 to 15. At 600° C degradation to concentrations below 0.1 ng/g is observed.     

Thermodynamic behaviour of sodium and calcium based sorbents in the emission control of waste incinerators

The dry treatment of flue gas produced by incineration processes is discussed thermodynamically. The study investigates the theoretical limits achieved by sodium and calcium based sorbents in the removal of the pollutant species HCl, NOx and SO2. Calculations were performed varying the temperature and the molar ratio between the amount of the injected alkaline sorbent and the content of the pollutant gaseous species in the flue gas. Results show that sodium cation based sorbents are more efficient than calcium based ones in the whole investigated temperature range (100-600 degrees C). The higher effectiveness of sodium based sorbents is particularly remarkable towards hydrogen chloride, whose concentration can always be reduced below the values set by the environmental regulations. Possible improvements in the treatment efficiency of combustion fumes obtainable with sodium based sorbents can be mainly summarised in a lower concentration of HCl in the treated gas and in a partial reduction of NOx concentration.     

小型焚烧设施烟气中二噁英类的排放和控制

对中国典型的小型焚烧设施现状和二噁英类排放进行了初步调查研究,未经处理的小型垃圾焚烧设施烟气中二噁英类毒性当量(TEQ)大于6 ng/m3,小型火化机烟气中二噁英类TEQ大于5 ng/m3.设计并检验了布袋除尘器和活性炭滤布的二噁英类去除效果.仅使用布袋除尘器二噁英类去除率不高,布袋除尘器和活性炭滤布联用可以有效去除飞灰和气相中的二噁英类,去除率达到90%左右,可达到《生活垃圾焚烧污染控制标准》(GB 18485-2001)二噁英类排放标准.     

整体蜂窝陶瓷催化剂催化氧化法脱除低浓度VOCs的实验研究

本文讨论了目前有机污染物脱除的各种方法 ,并将催化活性组分担载在经Al2 O3 修饰的整体蜂窝陶瓷支撑体上 ,制备了催化氧化法脱除低浓度有机污染物 (VOCs)ZDL - 1催化剂 ,在固定床反应器进行了连续工艺条件实验。结果表明 ,ZDL 1催化剂具有低温启动性能好、脱除VOCs的效率高、稳定性好的突出优点 ,且床层压降低。为ZDL 1催化剂应用于不同过程脱除VOCs提供基础     

Practices in dioxin emission reduction by special regulatory enforcement and utilizing advanced control technologies for incinerators in Korea

This study strives to estimate the emission of dioxin and furthermore attempts to find the best technological control methods available for waste incinerators by investigating the emission status thereof. In order to incorporate the Stockholm Convention, a particular stringent law was promulgated in Korea and in recent years incinerators were forced to utilize better technological control. After the enforcement of special dioxin emission regulation in 2003, the average concentration of dioxin emitted from municipal and industrial waste incinerators decreased from 15.25 and 12.86 ng TEQ Nm(-3) to 5.53 and 4.96 ng TEQ Nm(-3) in 2001 and 2004, respectively. Based on test results at commercial plants, several best arranged sets of air pollution control devices (APCDs) were suggested in order to provide guidelines to help operators. These sets included combinations of spray dry absorbers, bag type filters, wet scrubbers, selective catalytic reductions and electrostatic precipitators. Different suggestions and real installations of APCD arrangement were investigated during the years around the regulation in effective. The results were presented depending on the capacity of the incinerators and different waste streams to observe the efforts to reduce dioxin emission by operators of incineration plants. The annual amount of dioxin emission from the incinerators is expected to be 212.5 g-TEQ in 2011 and 234.3g-TEQ in 2015, respectively, compared to 891.6g-TEQ recorded in 2001. The enforcement of new regulation and the installation of better APCDs showed the significant effect on such reduction. This reduction in dioxin emission from incinerators confirmed the nation's commitment to the regulatory requirement set by the Stockholm Convention.     

摩托车催化净化系统与整车匹配技术的研究

本文论述了摩托车排放控制催化净化系统的应用特点 ,并在与国内摩托车生产厂家进行催化净化系统匹配的试验基础上 ,提出了应用摩托车催化净化系统可能遇到的问题和解决方案     

多效热回收催化燃烧工艺对制药企业间歇性VOCs的处理及应用

为有效处理制药行业生产过程中产生大量间歇性VOCs,构建由蓄热、换热、回热、补热组成的多效热回收直接催化燃烧工艺,结合模糊PID温度控制策略,以500 g·m⁻³铂钯合金镀在蜂窝陶瓷载体上为催化剂,处理某制药行业排放的间歇性有机废气,验证该工艺在处理制药行业排放的间歇性有机废气的可行性。结果表明：在制药行业排放的VOCs质量浓度为22mg·m⁻³到6293 m g·m⁻³较大波动条件下,多效热回收催化燃烧工艺能稳定有效地净化制药行业排放的有机废气,且净化后排放的VOCs浓度均小于20 mg·m⁻³,综合处理效率大于97%;随着排放的VOCs质量浓度的增高,处理效率也越接近100%;采用该工艺后,年平均运行成本为35.72×10⁴元,与传统工艺相比,运行成本降低了27%以上。由此可知,多效热回收催化燃烧工艺能够有效处理制药行业间歇性VOCs。本研究成果可为制药行业或其他行业的间歇性VOCs治理提供参考。     

加油站的烃类VOCs污染及其治理技术

加油站因储运轻质油品而产生的烃类VOCs对健康、环境、安全以及油品质量等带来了一系列负面影响.发达国家的常规治理措施主要是进行密闭卸油和密闭发油,对加油站的设备安装、管线布置、运营管理等都有一些具体要求;进入21世纪后美国又提出了强化加油站油气回收处理的观点,相应的技术、设备及法规也都日益健全.国内目前对加油站烃类VOCs污染的治理工作与发达国家相比差距很大,应该尽快从烃类VOCs回收处理的专用膜分离装置入手进行相关研究和产品开发.     

活性炭吸附和脱附-等离子体氧化净化有机废气的研究

根据滑动弧放电等离子体适于降解高浓度有机物废气的特性,结合活性炭吸附法,提出了吸附器的吸附浓缩和热脱附-等离子体氧化净化有机废气的方法。在活性炭吸附过程中,最初2 h内甲苯净化率达到100%,随着时间的增加净化率下降;在热脱附滑动弧放电等离子体净化过程中,甲苯降解效率最高为97.3%。将滑动弧放电等离子体反应器出口气相产物收集进行FT-IR检测,发现放电后有CO2、CO、H2O和NO2产生,并分析了甲苯的降解机理。     

Evaluation of the leachability of polychlorinated dibenzo-p-dioxins and dibenzofurans in raw and solidified air pollution control residues from municipal waste incinerators

Leachability of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from raw and solidified air pollution control (APC) residues with selected solvents, including acetic acid, simulated acid rain, humic acid, linear alkylbenzene sulfonate (LAS) and n-hexane was investigated. High-chlorinated PCDD/F congeners were observed in all leachates of raw APC residue samples, with the largest total leaching concentration (61.60 ngm(-3); 0.30 ngI-TEQm(-3)) from treatment with humic acid. Low-chlorinated congeners were mainly leached with LAS and n-hexane. Solidification and stabilization (S/S) processes with cement and sulfur-containing chelating agent decreased the leachability of PCDD/Fs by up to 98% with humic acid and LAS as solvents. However, S/S processes enhanced the leachability of both high- and low-chlorinated PCDD/F congeners with n-hexane as the solvent, which largely increased the toxic equivalent quantity of leachates. These results suggest that conventional S/S processes may effectively restrain the release of PCDD/Fs when APC residues are leached with rain water or natural organic compounds (e.g., humic acid), but may have a deteriorated effect when APC residues are leached with nonpolar organic solvents (e.g., n-hexane) coexisting in the landfill sites.     

Pt-CuMnCeOx/堇青石微波催化燃烧VOCs性能

微波催化燃烧是一项新的VOCs处理技术,提升VOCs处理效率的关键在于开发催化活性更高、性能更稳定的催化剂。将贵金属Pt与铜锰铈金属氧化物复合制备了Pt-CuMnCeO_x/堇青石催化剂,SEM、BET和XRD表征基础上测试催化剂对双组分VOCs-甲苯和乙酸乙酯的催化活性与稳定性。研究表明,Pt的复合提高了催化剂表面活性颗粒的分散性,增大了催化剂的比表面积和孔体积,升高了铜锰价态而提高了催化剂的低温催化活性。微波功率40 W时,Pt-CuMnCeO_x/堇青石催化剂的甲苯和乙酸乙酯的降解效率高出CuMnCeO_x/堇青石16%和11%;微波功率70 W时,Pt-CuMnCeO_x/堇青石催化剂可完全去除甲苯和乙酸乙酯,总VOCs去除率达97%左右且活性保持稳定。本研究结果可为微波催化燃烧VOCs技术提供参考。     

Removal efficiencies of PCDDs/PCDFs by air pollution control devices in municipal solid waste incinerators

Removal efficiencies of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) by air pollution control devices (APCDs) in the commercial-scale municipal solid waste (MSW) incinerators with a capacity of above 200 ton/day were evaluated. The removal efficiencies of PCDDs/PCDFs were up to 95% when the activated carbon (AC) was injected in front of electrostatic precipitator (EP). Spray dryer absorber/bag filter (SDA/BF) had high removal efficiency (99%)) of PCDDs/PCDFs when a mixture of lime and AC was sprayed into the SDA. When the AC was not added in scrubbing solution, the whole congeners of PCDDs/PCDFs were enriched in the wet scrubber (WS) with negative removal efficiencies of -25% to -5731%. Discharge of PCDDs/PCDFs was decreased with increasing the proportions of AC added in scrubbing solution. Selective catalytic reduction (SCR) system had the removal efficiencies of up to 93% during the test operation.     

挥发性有机物低温等离子体降解的影响参数研究

作为一类重要的有机污染物,挥发性有机物的危害已引起了世界各国的广泛关注。以挥发性有机物代表物质苯为研究对象,考察了多种实验参数对苯降解特性的影响。在高频电源条件下,对于施加电压、电源频率及反应器参数（包括管径、有效长度、电极材料和电极直径）与苯去除率的关系进行了研究。结果表明,高施加电压、高电源频率有利于苯的降解。管径较小、有效长度较长、内电极直径较大、内电极材料为钨的反应器对于苯的去除效果明显。反应器参数与电源的匹配问题对于提高污染物去除率及节能降耗方面十分重要。     

碳纳米管催化臭氧降解PFOS动力学与过程控制

针对全氟化合物难降解问题,通过碳纳米管（CNT）诱导臭氧高级氧化路径,研究非均相催化体系对高稳性全氟辛烷磺酸（PFOS）的降解效能与机制。结果表明：CNT介质可催化臭氧通过C-F断键对PFOS强制氧化分解,其准一级降解常数（k=0.037 min-1,5 mg·L-1 CNT）均高于碱式臭氧处理（k=0.009 min-1,pH=11）以及高负荷活性炭颗粒（k=0.013 min-1,5 g·L-1 GAC）;溶液pH是控制催化过程的重要因素,酸性或碱性环境由于PFOS吸附阻隔均不利于CNT表面与溶解O3的接触催化反应;结合羟基自由基淬灭实验,推测CNT通过表面石墨层促成·OH大量生成并在固/液界面原位降解PFOS。研究结果可为开发利用CNT介质强化臭氧水处理过程提供科学依据。