【作者】 罗思义；

【导师】 肖波； 胡智泉；

【作者基本信息】 华中科技大学 ， 环境工程， 2010， 博士

【摘要】 为了提高城市生活垃圾资源化处理的效率,需要对垃圾进行破碎预处理,我国对垃圾的破碎都主要是针对垃圾中的硬质和脆性物料,破碎设备以锤式破碎机和冲击式破碎机为主,但由于有机生活垃圾中高韧性、低硬度的固体废弃物如修剪下来的树枝、旧橡胶轮胎、塑料和纸等含量较大,而冲击破碎的方式对含水率要求高和对韧性物料破碎效果差的缺点远远满足不了对有机垃圾破碎的要求。本文针对有机城市生活垃圾密度小、间隙大、低硬度和韧性物质含量高的特点,提出了垃圾压缩剪切破碎的新方法并设计制造了一台实验型垃圾破碎机,通过破碎实验对这种破碎方法的可行性以及影响破碎机性能的因素进行了分析和探讨。并对破碎后粒径对城市生活垃圾热解和水蒸汽气化特性的影响进行了研究。(1)采用某一组分的城市生活垃圾(厨余57.6wt.%,纸板6.9wt.%,织物7.2wt.%,木竹19.7wt.%,塑料8.6wt.%)作为实验原料,在实验型破碎机上进行垃圾破碎实验,以破碎产品粒径分布和破碎单位功耗作为衡量指标,探讨破碎机工作参数如压缩室压力、转子转速、刀片间距、工作负荷和进料方式对破碎机性能的影响。结果表明：实验型破碎机能够有效地对有机生活垃圾进行破碎处理,在最佳工况下,破碎产品中粒径达到设计要求(粒径小于10mm)的颗粒重量百分含量为85.7%,破碎单位功耗为13.2J/g；垃圾在破碎前受到压力越大,破碎效果越好,单位能耗越低；增加转速虽然能降低破碎能耗,但是影响破碎产品质量；减小刀片间隙可以提高产品中小粒径颗粒的比重,但能耗较高,对于韧性高的物料如塑料的破碎,刀片间隙应相应地减小,使破碎空间等于或稍小于破碎要求粒；为了保证生产过程的稳定性和安全性,需严格控制垃圾破碎机工作负荷,在负荷允许的范围内进行生产操作；与单向进料的破碎方式相比,双向进料提高了破碎机的工作效率,降低了破碎单位能耗,对破碎产品的粒径分布影响不明显。(2)通过改变垃圾组分、含水率和原料尺寸,探讨原料自身特性对破碎机性能的影响。结果表明：新型破碎机能够用于不同类固体废弃物的破碎处理,但对于低硬度物料的破碎更有效；物料中含水率的增加不利于垃圾的破碎,且在低工作压力下,含水率对破碎产品质量和单位能耗的影响更显著；垃圾原料尺寸对破碎产品粒径分布的影响不明显,原料尺寸越小破碎能耗越低。(3)将破碎后的产品进行筛分,采用自行设计的管式炉热解反应器和上吸式固定床气化反应器作为小试平台,探讨粒径在不同的温度下对垃圾热解和水蒸气气化特性的影响。结果表明：增加反应温度可以降低焦油和焦炭产率,提高气体产量；粒径越小气体产量越高,焦油和焦炭量越低；粒径的影响随着温度的升高逐渐减小；热解和气化燃气中H2和CO的含量随着粒径的减小而增加,CO2降低；热解和气化温度越高,原料粒径越小,反应进行的越完全,残留的焦炭中C和H元素含量越低,灰分的含量相对增加。(4)以自行研制的垃圾压缩装置作为实验平台,探讨垃圾粒径和压力对垃圾体积压缩比的影响。在自制的连续性进料的固定床催化热解炉中进行了中试研究,探讨粒径和进料压力对垃圾催化热解产气特性的影响,得出了以下结论：减小原料粒径和增加进料压力能够增加垃圾体积压缩比,减小垃圾粒径都能够减低垃圾催化热解燃气中氧气和氮气的含量,提高燃气质量。更多还原

【Abstract】 The breakage pretreatment of municipal solid waste (MSW) is necessary to increase the uniformity and ratio of surface area and of MSW to improve the efficiency of the subsequent processing step, while the breakage of MSW mainly concentrates on the hard and brittle materials of MSW in china. The ductile solid waste which makes the hammer crusher difficult to meet the requirements of the breakage of MSW, however, accounts for a large proportion of MSW. It is powerless for the hammer crusher to crush the moisture and ductile material.Based on the composition and volume-mass properties of MSW (i.e., unit weight, void ratio, and water content), a novel shear shredder for organic MSW was presented. The reliability of the shredder was investigated and the influencing factors were studied.(1) Some certain composition MSW (kitchen garbage 57.6 wt.%, paper 6.9 wt.%, textile 7.2 wt.%, wood 19.7 wt.%, plastic 8.6 wt.%.) was chosen as testing materials, and the product size distribution and specific energy were taken as measurement index. The breakage tests were carried out in the lab-scale shear shredder to evaluate the effects of working parameters:hydraulic pressure, rotor speed, distances between rotating blades, working load and feeding mode. The results show that the shredder is suitable for the pulverization of MSW with specific energy and fine particles proportion being 13.2 J/g and 85.7%, respectively, under optimal operating conductions. With increasing hydraulic pressure the specific energy is reduced, and size distribution of product is finer. When hydraulic pressure is constant, the specific energy decreases with increasing rotor velocity, while the products size distribution is coarser; the fines proportion (particles below 10mm) shows increasing trend with decreased distances between rotating blades, however, the specific shows opposite trend. For the breakage of plastic, the distance should be smaller than the desired particle size. The specific energy is the lowest when the shredder is operated at the designed working load. Compared with single-course shredder, the two-inlet operation mode improves shredding efficiency and reduces energy consumption to a great extent. With the double-inlet operation, about 73%as much energy is used per gram as with the single-course shredder; (2) The effects of raw materials characteristics such as feed composition, feed moisture and raw materials size are investigate in the paper. The shredder is much more effective for the pulverization of soft, ductile and fibrous materials (kitchen garbage and leaves in the test), but it is not good at the brittle material (branch). There is a tendency for the fine production in products to decrease with the increasing amounts of water content in the feed; with the increasing feed moisture, specific energy shows an increasing trend; under lower hydraulic pressure, the specific energy and product size distribution are more sensitive to the feed moisture than under higher hydraulic pressure. The effect of raw materials size on product size distribution is not evident, while smaller size would result in lower specific energy.(3) Pyrolysis and steam gasification of MSW were carried out in a small-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on product yield and composition. Particle size and temperature had integrated effects on product yield and composition:higher temperature resulted in higher gas yield with less tar and char, and, at the same temperature, dry gas yield increased with a decrease in particle size, and char and tar yield decreased. The differences due to particle sizes in pyrolysis and gasification performance practically disappeared at the highest temperatures tested. Smaller particle sizes resulted in higher H2 and CO contents for both pyrolysis and gasification of MSW. Smaller particle size leaded to lower C and H contents, as well as higher ash content in the char.(4) The MSW compaction tests were carried out in the self-designed compaction facility in order to evaluate the effect of feeding pressure and material size on volume compression ratio. And MSW catalytic pyrolysis was conducted in the pilot-scale reactor to investigate the influences of particle size on fuel gas quality. The results show decreasing feed size and increasing feeding pressure could increase MSW volume compression ratio, resulting in the decreasing of O2 and N2 contents in the fuel gas. With the increase of feeding pressure, the effect of particle size becomes less pronounced.更多还原