| Natural gas, as a kind of valuable resource, applied in many kinds of production and normal living areas. With the development of the status in the world energy structure, natural gas purification industry play a critical role in the world. After several decades of research, has made great achievements in natural gas desulfurization, bur away from foreign, there is still a gap. At present, the amine desulfurization technology is the mostly widely used desulfuration technology for various refineries and gas plants. Among them, MDEA becoming the most widely used in the amine desulphurization desulfurization solvent because of its advantages of high sour gas load, the good selectivity for H2S, low corrosive and not easy foaming. But the type of feed gas in industry is complex, so the conventional MDEA aqueous solution can't solve all the contradictions. Especially H2S and CO2 content in the feed gas is not too high and the CO2 content is lower than 2% which is the national standard (GB 17820-2012) of commercial natural gas, but CO2/H2S is too high (more than 10, even than 100). The requirement for desulfurizing solvent is on the premise of guarantee the H2S purification degree, as far as possible, strengthen the solvent selected absorption function in order to reduce energy consumption, and improve the quality of sour gas entering the sulfur recovery unit. This paper in view of the feed gas which CO2/H2S is too high, and research the desulfurizer which has high selective of H2S, five kinds of sterically hindered amine were synthesized, and evaluate its desulfurization performance, regeneration performance, corrosion resistance, foam, etc. The main results were as follows:1. The synthesis of sterically hindered amine. In this paper, design experiment method and synthesis BMAP, BEAP, BTAP, TBDE, and studied the new method to synthetic TBEE, and then the experimental conditions were optimized. On this basis, BMAP, BEAP, BTAP, TBDE amine TBEE is synthesized. BMAP, BEAP, BTAP and TBDE are the new sterically hindered amine, those methods have not been reported by far. TBEE is a industrialized sterically hindered amine.2. The desulfurization effect evaluation of sterically hindered amine. With the removal efficiency of H2S and CO2, acid gas load such as index to evaluate the desulfurization effect of the solvent. Respectively test the desulfurization efficiency of the five kinds of sterically hindered amine effect to feed gas (CO2:H2S=10) in the temperature of 20?,30?,40?,50?, 60? and concentration of amine liquid are 10%,20%,30%,40%,50%, and compared with the same condition of MDEA solution. The experimental results show that under the condition of the same temperature and concentration of six kinds of amine fluid desulfurization selectivity (S) in this order:S (TBDE)> S (BEAP)> S (BTAP)> S (TBEE)> S (BMAP)>S (MDEA); Six kinds of sterically hindered amine of acid gas load in this order L(TBDE)>L(BTAP)>L(TBEE)>L(BEAP)>L(BMAP)>L(MDEA).3. The regeneration performance evaluation of sterically hindered amine. Regeneration experiments were taken in six kinds of sterically hindered amine, and the experiment temperature is 120?, the regeneration time for 20 min. Through detection of H2S and CO2 content in the solution that regenerated, it showed that rarely acid gas content in the regeneration of lean solution so that Regeneration is completely. After the regeneration solution for H2S content in the solution after the second desulfurization decarburization is reduced by 2%?8% compared with a desulfurization and CO2 content is reduced by 3% 20%. In the same conditions, the sterically hindered amine carbon capacity decline rate and sulfur capacity decline rate is lower than MDEA, its show that sterically hindered amine solution is easier to regenerate than MDEA solution, and renewable energy consumption is lower than MDEA.4. The corrosion resistance evaluation of sterically hindered amine. Using EDS, XRD and SEM analysis of 20# steel in saturated H2S and CO2 corrosion products of MDEA solution, corrosion is mainly caused by the acid gas that dissolved in alcohol amine, corrosion products mainly include FeS, Fe2S and FeCO3. By weight loss method and electrochemical method, analysis the corrosion situation of 40% five kinds of sterically hindered amine on 20# steel,: Weightlessness experiment results show that at low temperature (30"C to 50?),20# steel in the concentration of 40% MDEA and sterically hindered amine liquid is close to weightlessness corrosion rate and are relatively low. With the increase of temperature, corrosion rate increases, when the temperature is greater than 70?, the corrosion rate increased rapidly. Electrochemical experimental results show that the saturated H2S/CO2 concentration of 40% MDEA, BMAP, BEAP, BTAP, TBEE and TBDE solution, the corrosion rate of steel 20# are controlled by the charge transfer resistance, metal anode surface adsorption of metal ions has a great influence on the anode surface activation dissolve. As temperatures rise, the potential turns of 20# steel in alcohol amine solution negative, the charge transfer resistance reduced, metal anode activation dissolution rate speeding up, corrosion rate greatly increased. Contrast electrochemical experimental results of saturated acid gas concentration of 40% of six kinds of amine liquid corrosion of 20# steel all has certain corrosion rate size order for TBDE> BTAP> TBEE> BEAP> BMAP> MDEA. The experimental results coincide with the weightlessness to experimental results.5. The foaming evaluation of sterically hindered amine. According to the industry standard SY/T 6538-6538 in formula type selectivity desulfurizing solvent method to test the solvent, carried out on the five kinds of sterically hindered amine foaming evaluation, the experimental results show that the five kinds of sterically hindered amine defoaming time are less than 35s, so that BMAP, BEAP, TBEE, BTAP and TBDE unfavorable foaming.In this paper, five kinds of sterically hindered amine have synthesized. They has high selectivity of H2S, high sour gas load, low renewable energy consumption, corrosion resistance is weak of 20# steel at low temperature conditions, difficult to foaming and synthetic route is simple. So it is possibility to be industrialized. Those research results to guide the selective desulfurization of natural gas has the important meanings. |
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