附壁振荡脉动流变压吸附净化天然气研究

There are the uneven gas velocity, the different residual time of gas, the largely different adsorption saturation leading to low purification efficiency, waste of renewable gas and renewable energy in adsorption bed of the existing pressure swing adsorption and purification of natural gas . The external excitation attached wall oscillation pulse flow and pressure swing adsorption natural gas purification technology is proposed to overcome these limitations of the existing technology of adsorption bed. The external excitation oscillator without moving parts and efficient multi-unit controll pulsatile flow, turns intermittently through different regions of the adsorbent bed section, in order to break through the dynamic adsorption flow area and flow dead zone. Then the bed layer section around the gas velocity tends to be uniform, thereby improve purifying efficiency and separation coefficient ..The main contents are as follows: (1) Study the small expansion fluidic oscillator parameter coupling optimization and oscillation control law, master the oscillator geometric parameters on the oscillation pulsation flow and loss of the occurrence and development mechanism, separation mechanism and coupling law of the attached wall switch impact loss and boundary layer in branch channel; (2) To study the enhancement characteristics of mass transfer in pulsating adsorption, and to clarify the correlation between the enhancement effect and the frequency of pulsating flow, the mode and the parameters of bed; (3) Construction of particle spoiler model under pulsating flow,to reveal the mechanism of pulsating flow on the enhanced mass transfer on the surface of adsorbent particles; (4) Analyze the flow field and structure of the new pulsating adsorber, and obtain the change and dynamic law of the natural gas component concentration.

以变压吸附净化天然气为背景，针对现有工艺吸附床层各处气速不均、滞留时间快慢使出层各点气体的净化率不一、和床层内吸附剂吸附饱和度差异大、净化效率低、浪费再生气和再生能量问题，提出以外激励附壁振荡生成多股交替脉动流，导流通过吸附剂床层划片分割各区域的变压吸附净化天然气方法，即由无动件外激励振荡器高效产生多股可控脉动流，轮流间歇地穿过吸附剂床层截面的不同区域，以期动态冲破吸附剂缓流区和流动死区，使床层截面各处气速不断调整均匀，提高净化效率和分离系数。.研究：(1)小膨胀比射流振荡器参数耦合优化与振荡控制，几何参数对振荡脉动流态制约与损失抑制，高效获得多股时均脉冲流方法与床层区域分配；(2)脉动吸附传质强化机制与特性，与脉动流频率、模态及床层参数的关联耦合规律；(3)脉动流作用下的颗粒扰流模型，对吸附剂颗粒表面渗透强化传质机理；(4)新型脉动吸附器流场特征与优化结构，天然气组分浓度动态变化规律。

项目针对现有吸附工艺床层内气速不均、滞留时间不同使出口气体净化率不一、净化效率偏差及吸附柱内吸附剂吸附饱和度差异大等问题，提出了外激励附壁振荡器产生一定频率的脉动射流气体、并作为变压吸附净化天然气进口原料气的工艺及技术方案，研究内容及取得的成果主要有：.①建立了外激励附壁振荡器模型与实验装置，研究了振荡器流场边界形位、流道几何参数及进口压力对振荡流场与流动损失的影响，揭示了特征尺寸与振荡器总压保持率和最小激励流变化规律，获得了时均脉动射流实现方法与吸附柱内部床层区域均匀分配方案，为变压吸附原料气体脉动性提供了技术解决方案。.②数值模拟与实验测试双级附壁振荡器出口压力数值，研究结果表明：第二级出口激励波形效果较好，实验测试出口总压保持率K高达70.3%，各分支的射流时均一致性、能效特性均明显优于多管音波式振荡器。.③脉动流进气改善了吸附柱内流动死区和吸附剂吸附不均匀性、及破坏阻碍吸附的气体附面层，提高了吸附量，延长了CH4/CO2穿透时间及增大了分离系数，有效提高了CH4/CO2分离效果；工艺研究确定了脉动频率、进气压力与进气流量等最佳参数，13X分子筛脱碳工艺优于5A分子筛与活性炭。.④研究获得了脉动射流压力场、速度场、温度场变化规律及脉动流频率、模态及吸附柱参数的关联规律，进一步明晰了脉动射流下吸附柱内天然气组分浓度变化的动力学规律，掌握了吸附剂颗粒表面吸附强化的传质机理与影响因素。.⑤为脱除天然气中含有的汞元素，本项目同时研究了CuO/Al2O3脱汞剂制备工艺及脱汞性能，并分别利用硫与氯化铜改性获得了新型脱汞剂，在卤素Cl和过渡金属Cu共同作用下，氯化铜改性脱汞剂性能明显高于氧化铜改性脱汞剂，但与硫化处理后的脱汞机理一致；搭建了脱汞实验装置，测试表明，新型脱汞剂性能优异，有进一步放大的可行性。