規(guī)整催化劑甲烷化過程數(shù)值模擬及反應(yīng)器設(shè)計
發(fā)布時間：2018-07-24 21:14
【摘要】：輸送床-固定床二段式甲烷化工藝是由輸送床和固定床組合而成的,甲烷化反應(yīng)是放熱量高的反應(yīng)。輸送床優(yōu)傳熱性能優(yōu)越,其發(fā)生甲烷化反應(yīng)的床層溫度接近等溫,大部分原料氣在輸送床發(fā)生反應(yīng),剩下小部分沒有反應(yīng)的氣體在固定床中發(fā)生反應(yīng)。該工藝中出現(xiàn)的問題是輸送床中顆粒相互碰撞帶來的顆粒粉末可能會進入固定床中造成傳統(tǒng)堆積催化劑空隙的阻塞進而增加床層壓降。為避免出現(xiàn)該問題,需要研究低壓降甲烷化固定床反應(yīng)器。低壓降甲烷化固定床反應(yīng)器選用的是規(guī)整填料的軸向流反應(yīng)器。以ANSYS workbench為平臺,采用數(shù)值模擬的方法分別進行了四部分研究。首先對同樣發(fā)生表面反應(yīng)的平板反應(yīng)器進行模擬,并用相同的方法對單孔道進行模擬。采用單孔道替代多孔道的方法對規(guī)整催化劑進行模擬,分別模擬了發(fā)生表面反應(yīng)和體積反應(yīng)的規(guī)整催化劑。第二部分是改變?nèi)肟跍囟�、入口壓力、入口速度、入口濃度等操作參�?shù),分別研究操作參數(shù)對固定高度的規(guī)整催化劑達到的轉(zhuǎn)化率的影響和達到工藝要求的轉(zhuǎn)化率需要的催化劑高度的影響。第三部分是對發(fā)生甲烷化的床層進行研究。研究孔道形狀及尺寸對傳遞、壓降、轉(zhuǎn)化率的影響;研究孔道材質(zhì)和催化劑床層間隙對甲烷轉(zhuǎn)化率的影響;研究達到相同轉(zhuǎn)化率的條件下,流速、尺寸與催化劑用量的關(guān)系。第四部分是確定床層流速分別為0.95m/s、1.81m/s對應(yīng)的固定床的工藝參數(shù)與結(jié)構(gòu)尺寸,并對固定床入口結(jié)構(gòu)進行優(yōu)化。進而對反應(yīng)器進行強度設(shè)計,并利用熱-流-固耦合的方式對設(shè)計反應(yīng)器進行強度校核,使最終設(shè)計的反應(yīng)器滿足強度需要。研究結(jié)果表明:(1)通過驗證對比,使用模擬平板甲烷化反應(yīng)器方法模擬規(guī)整催化劑,使用單孔道代替多孔道模擬規(guī)整催化劑的方法是正確的。(2)轉(zhuǎn)化率隨流速增加而降低;壓力越高,轉(zhuǎn)化率越高;入口溫度越高,轉(zhuǎn)化率越高,入口溫度需要在260℃-320℃之間;固定床入口濃度隨前段流化床轉(zhuǎn)化率決定,流化床轉(zhuǎn)化率大于65%,固定床內(nèi)催化劑不會失活;獲得了濃度-流速-轉(zhuǎn)化率關(guān)系式。(3)圓形孔道傳遞效果最好,正方形次之,三角形最差。但三角形孔道壓降和轉(zhuǎn)化率最好,圓形孔道最差。孔道尺寸越小轉(zhuǎn)化率越高。對于進料濃度大的規(guī)整催化劑,為避免催化劑失活,可以選用金屬材料的規(guī)整催化劑,并外壁保持恒溫。催化劑床層之間的間隙對氣體混合沒有效果,規(guī)整催化劑沒有必要設(shè)置分段。要達到工藝要求轉(zhuǎn)化率,流速與發(fā)生表面反應(yīng)的規(guī)整催化劑用量沒有關(guān)系。(4)確定了床層內(nèi)流速為0.95m/s、1.81m/s對應(yīng)的反應(yīng)器結(jié)構(gòu)尺寸;需要在反應(yīng)器內(nèi)壁增加隔熱材料才可以達到強度要求。
[Abstract]:The two-stage methanation process of conveying bed and fixed bed is composed of conveying bed and fixed bed. The methanation reaction is a reaction with high heat release. The bed temperature of the methanation reaction is close to isothermal, most of the feedstock gas reacts in the conveying bed, and a small part of the unreacted gas reacts in the fixed bed. The problem in this process is that the particle powder caused by the collision of particles in the conveying bed may enter the fixed bed resulting in the blockage of the gap of the traditional piling catalyst and thus increase the pressure drop of the bed. In order to avoid this problem, it is necessary to study the low pressure demethanation fixed bed reactor. The fixed bed reactor for low pressure methanation is an axial flow reactor with regular packing. Taking ANSYS workbench as the platform, four parts of research are carried out using numerical simulation method. At first, the surface reaction of the plate reactor is simulated, and the single channel is simulated by the same method. The surface reaction and volume reaction of the regular catalyst were simulated by the method of single channel instead of the multi-pore channel. The second part is to change the operating parameters such as inlet temperature, inlet pressure, inlet velocity, inlet concentration, etc. The effects of operation parameters on the conversion of the regular catalyst with fixed height and the catalyst height required to meet the conversion requirements of the process were studied respectively. The third part is to study the methanation of the bed. The effects of pore shape and size on transfer, pressure drop and conversion rate were studied. The effects of pore material and catalyst bed gap on methane conversion were studied. The relationship between flow rate, size and catalyst dosage was studied under the same conversion rate. The fourth part is to determine the process parameters and structural dimensions of the fixed bed with a flow velocity of 0.95m / s and 1.81m / s, respectively, and optimize the structure of the inlet of the fixed bed. Then, the strength of the reactor is designed, and the design reactor is checked by the thermal-fluid-solid coupling method, so that the final designed reactor can meet the strength needs. The results show that: (1) through verification and comparison, it is correct to use the simulated plate methanation reactor method to simulate the regular catalyst, and to use the single-pore channel instead of the multi-pore channel to simulate the catalyst. (2) the conversion rate decreases with the increase of the flow rate; The higher the pressure, the higher the conversion rate, the higher the inlet temperature, the higher the conversion rate, and the higher the inlet temperature is between 260 鈩，
本文編號：2142674
[Abstract]:The two-stage methanation process of conveying bed and fixed bed is composed of conveying bed and fixed bed. The methanation reaction is a reaction with high heat release. The bed temperature of the methanation reaction is close to isothermal, most of the feedstock gas reacts in the conveying bed, and a small part of the unreacted gas reacts in the fixed bed. The problem in this process is that the particle powder caused by the collision of particles in the conveying bed may enter the fixed bed resulting in the blockage of the gap of the traditional piling catalyst and thus increase the pressure drop of the bed. In order to avoid this problem, it is necessary to study the low pressure demethanation fixed bed reactor. The fixed bed reactor for low pressure methanation is an axial flow reactor with regular packing. Taking ANSYS workbench as the platform, four parts of research are carried out using numerical simulation method. At first, the surface reaction of the plate reactor is simulated, and the single channel is simulated by the same method. The surface reaction and volume reaction of the regular catalyst were simulated by the method of single channel instead of the multi-pore channel. The second part is to change the operating parameters such as inlet temperature, inlet pressure, inlet velocity, inlet concentration, etc. The effects of operation parameters on the conversion of the regular catalyst with fixed height and the catalyst height required to meet the conversion requirements of the process were studied respectively. The third part is to study the methanation of the bed. The effects of pore shape and size on transfer, pressure drop and conversion rate were studied. The effects of pore material and catalyst bed gap on methane conversion were studied. The relationship between flow rate, size and catalyst dosage was studied under the same conversion rate. The fourth part is to determine the process parameters and structural dimensions of the fixed bed with a flow velocity of 0.95m / s and 1.81m / s, respectively, and optimize the structure of the inlet of the fixed bed. Then, the strength of the reactor is designed, and the design reactor is checked by the thermal-fluid-solid coupling method, so that the final designed reactor can meet the strength needs. The results show that: (1) through verification and comparison, it is correct to use the simulated plate methanation reactor method to simulate the regular catalyst, and to use the single-pore channel instead of the multi-pore channel to simulate the catalyst. (2) the conversion rate decreases with the increase of the flow rate; The higher the pressure, the higher the conversion rate, the higher the inlet temperature, the higher the conversion rate, and the higher the inlet temperature is between 260 鈩，
本文編號：2142674
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