论文总字数：31300字

摘 要

焦油是生物质气化过程不可避免的副产物，易与水、灰和炭颗粒等结合，堵塞管道和阀门，腐蚀金属；不完全燃烧，会造成对环境的二次污染（多环芳烃和PM2.5），并产生炭黑等颗粒，对内燃机和燃气轮机叶轮损害严重；能量占燃气总量的5~15 %，降低了气化效率。焦油的处理问题已成为制约生物质气化技术产业化应用的主要瓶颈。传统的焦油处理方法净化度低、费用高，并会产生二次污染。油基脱焦法（OLGA）采用溶剂进行冷却和吸收脱焦，一级脱焦得到混合粉尘的悬浊液，溶剂回收难度大。

本文将乙烯裂解气急冷过程和吸收/吸附单元操作进行集成，构建生物质燃气焦油自冷却耦合吸收/吸附两级脱除过程，为焦油深度脱除提供新思路。主要研究内容如下：在现有的焦油自冷却耦合吸收/吸附脱除实验装置上，选取正十二烷和环己烷作为焦油模拟物，研究其在自冷却耦合吸收过程中的分级脱除行为；分析了耦合脱除机理和循环再生性能。引入吸附单元，对生物质燃气焦油两级脱除过程实验装置进行改建。选取和真实焦油更相似的苯和萘作为轻、重焦油模拟物，以活性炭和木屑为吸附剂，对该过程的焦油脱除和循环再生性能进行了研究。在此基础上，搭建了生物质焦油轻组分深度吸附脱除实验装置。对装置进行了检漏、保温等工艺流程；并对油浴温度、进样时间、气体流量、色谱柱温等参数进行了校订。选取轻焦油的主要成分苯酚和萘作为模拟物进行实验，以分子筛MCM-41、CMS-3KT-172、CMS-270为吸附剂，对其焦油脱除和循环再生性能进行了分析。

结果表明，焦油自冷却耦合吸收/吸附两级脱除设想切实可行。采用改性柴油作为吸收剂，可将正十二烷和环己烷分别脱除至1 %。系统对正十二烷，主要起到冷却作用。对于环己烷，冷却器起到冷却和协同吸收作用；吸收器起到深度脱除作用，将环己烷脱除至1 %以内。50 ℃热吹扫125 min，改性柴油可得到有效再生。吸附脱除实验结果表明，对于苯，微孔和窄中孔活性炭的吸附脱除性能更好；对于萘，窄中孔的吸附作用较大。微孔和介孔复合的结构，既有利于焦油的深度脱除，又利于提高焦油分子的扩散性能。基于吸附的两级焦油脱除过程，可将轻、重焦油模拟物深度脱除，净化效果优于基于吸收的过程。新装置参数调节结果表明，当油浴温度为80 ℃、进样时间为5 s、气体流量为20 ml/min、色谱柱温为180 ℃时，对苯酚和萘有很好的分析效果。分子筛对轻焦油模拟物苯酚和萘都有很好的脱除效果，脱除至1 %以内；其中MCM-41分子筛脱除效果最好，也有良好的循环再生性能。为以后的研究奠定了一定的基础。

关键词：生物质燃气 焦油 自冷却 吸收/吸附 耦合脱除

ABSTRACT

Biomass gasification process will inevitably product tar. During the subsequent usage of the gas, Tar easily combines with water, ash and carbon particles and other impurities, then plugs valves and pipelines, and corrodes metals; Tar is difficult to burn completely, so carbon particles is easy to cause serious damage to the engine and the turbine; Tar contains in the energy accounted for 5% to 15% of the total energy of gas, however, it is difficult to use in the process of gas combustion, decreasing the gasification efficiency. Therefore, tar, in the process of biomass gasification, is a major obstacle to large-scale industrialized utilization. Traditional method for tar purification is less effective and expensive, and could lead to the secondary pollution. Tar is cooled and absorbed by solvent in Oil-based decoking method (OLGA), which leads to a suspension, and it is difficult to recycle.

The Self-Cooling Coupled with Absorption/Adsorption Technology (SCCABT /SCCADT), or named as the two-stage tar removal technology, integrating ethylene cracking gas quench process with absorption/adsorption unit operation, was developed to remove the biomass gas tar. Tar removal mechanism and behavior of this two-stage technology were studied and new method has been created. The main contents and results are as follows: An experimental apparatus of the SCCABT was established. Cyclohexane and n-dodecane were used as the simulated light and gravimetric tar respectively. The tar removal behavior in the SCCABT and the coupling removal mechanism were studied. And the mechanism and recycling nature of the removal process were investigated. The SCCABT experimental apparatus was modified with adsorption unit, to test SCCADT process. Selecting benzene and naphthalene which is more similar to the real biomass tar structurally, as light and heavy tar respectively, with activated carbon and wood chip as the tar adsorbent, tar removal performances of SCCADT were determined. Leakage detecting and heat preservation are conducted and temperature of oli, time of feed, flow rate of gas ,temperature of chromatograph are also checked. The adsorption behavior of benzene and naphthalene is investigated. Molecular sieves of MCM-41,CMS-3KT -172,CMS-270 are served as adsorbents.

The results show that this new method is feasible. If special diesel is worked as absorbent, n-dodecane and cyclohexane are removed by 99% respectively. n-dodecane serves as coolant, and cyclohexane serves as both coolant and absorbent. Diesel can be recycled after blowing 125 minutes with 50 ℃ air. The experiment shows that active carbon of micro-pore and narrow meso-pore is more preferred for benzene adsorption. While active carbon of narrow meso-pore is more appropriate for naphthalene. Microporous intergrating mesoporous structures of the adsorbent are beneficial to the deep removal of the tar effectively due to intensification of both adsorption equilibrium and dynamics. The SCCADT process can remove simulated light and heavy tar to near 0, as is more efficient than the SCCABT process. When the temperature of oil is 80℃, time of feed is 5 s, the flow rate is 20 ml/min, temperature of chromatograph is 180℃,prefect results can be received. Molecular sieve has good removal effect to light tar phenol and naphthalene content, which is removed to less than 1%; The MCM-41 molecular sieve is best, and have a good recycling performance. Works is also helpful to future studies.

Key Words: Biomass gas; Tar; Self-cooling; Absorb/sorption; Co-removal

目录

摘要 I

ABSTRACT Ⅲ

第一章 绪论 1

1.1 背景和意义 1

1.2 焦油及其危害 2

1.3 焦油的分类 3

1.4 煤焦油的处理方法及其局限 3

1.5 生物质燃气焦油脱除方法研究进展 4

1.5.1 焦油脱除方法的分类 4

1.5.2 消除法 4

1.5.3 回收法 5

1.5.4 基于回收法的焦油脱除系统应用实例 11

1.6 焦油脱除方法存在问题分析 12

1.7 本文主要研究内容 12

第二章 焦油脱除实验 14

2.1焦油自冷却耦合吸收脱除实验 14

2.1.1主要原料与试剂 14

2.1.2实验装置及测试过程 14

2.1.3分析方法 15

2.2 焦油自冷却耦合吸附脱除实验 16

2.2.1主要原料和试剂 16

2.2.2实验装置及测试过程 16

2.2.3比表面测定 17

2.3生物质焦油轻组分深度吸附脱除实验 17

2.3.1主要原料和试剂 17

2.3.2仪器、仪表、装置简介 18

2.3.3实验装置搭建步骤 18

2.3.4 轻焦油模拟物动态吸附性能测试步骤 19

第三章 结果与讨论 21

3.1 焦油自冷却耦合吸收脱除 21

3.1.1吸收剂的筛选 21

3.1.2 循环和再生性能 22

3.1.3本节小结 24

3.2焦油自冷却耦合吸附脱除 25

3.2.1自喷淋冷却过程萘和苯的脱除特性 25

3.2.2焦油动态吸附行为研究 26

3.2.3本节小结 29

请支付后下载全文，论文总字数：31300字