산화철 고속촉매에 의한 고농도 황화수소 제거 및 촉매재생 기술에 관한 연구

Abstract

In order to reduce the odor from leather processing company complex, we need a technology that removes effectively hydrogen sulfide from mainly odor gas stream. Objectives of this research are to develop and commercialize an essential element technology for removal high concentration hydrogen sulfide with high-efficiency and low-cost from leather processing company using pilot-scale plant in field. In this research, we studied regeneration activity of T. ferrooxidans type with various temperatures and initial substrate concentration conditions for obtaining high-speed catalyst regeneration technology. For development of high-efficiency desulfurization absorber, we researched the removal efficiency of hydrogen sulfide with various liquid & gas contact methods and spray types, using lab-sacle absorption tower. As various regeneration conditions of experiments, regeneration temperature was applied to 10 ～ 30℃, and initial substrate concentration was 10 ～ 30 g/L. The experimental results showed that regeneration period of ferrous oxide by T. ferrooxidans was delayed with decreasing temperature and increasing initial substrate concentration. The optimal regeneration temperature was 30℃ and regeneration velocity in the range of 10 ～ 30 g/L of substrate concentration was not highly different. In development of high efficiency desulfurization absorber, when the absorption height was over 50 cm, the removal efficiency of desulfurization was not increased. But as Fe3+ catalyst liquor was sprayed at higher absorption heights the removal efficiency was more increased. In the experiment of liquid & gas contact methods and gas supply types, when the retention time and substrate concentration was increasing, the removal efficiency was widely improved. The developed high-efficiency hydrogen sulfide removal technology can be apply to deodorization of high concentration of H2S producing facilities, treatment of tail-gas from Claus sulfur recovery plant, removal hydrogen sulfide from sour gas of oil refining process and treatment of sour gas exhausting from chemical factory like Rayon plant, barium salt production plants etc. This study consists of maily 5 chapts;

Chapt Ⅰ. Instruction The high concentration of hydrogen sulfide was produced from desulfurization process of petrochemical plant such as natural gas, cokes or oil refinery and wastewater treatment system of leather plant. Especially, tens of thousands ppmv of hydrogen sulfide gas was converted from sulfur compounds contained at natural oil and gas by desulfurication process. Emit-site of hydrogen sulfide was papermaking and leather plants and sewage water and night soils treatment plants. In this study, recovery capacity of iron oxide(Fe2+) was enhanced by T. ferrooxidans in high catalyst recovery and desulfurication system. And high efficiency hydrogen sulfide removal reactor was developed for stable removal on high concentration of hydrogen sulfide and reducing operating costs. First, using the lab-scale high catalyst recovery and desulfurication system, various factor such as height of reactor, spray way and catalyst concentration were estimated. Secondly, Using T. ferrooxidans, the control parameters such as temperature, substrate concentration etc. were evaluated for high efficiency recovery of catalyst. Finally, the parameters derived by lab-scale plant were made up using pilot-scale plant in field.

Chapt Ⅱ. Theory H2S is the representative material which can cause air pollution and odor. 'The clean Air Conservation Act' restricts H2S to 2 ～ 10 ppm in the waste incineration, Oil industry, pulping process facility and, refuse derived fuel facility. Also, 'Odor Control Law' restricts H2S to 0.02 ～ 0.06 ppm. Recently, in order to remove a high concentration of H2S, the various removal processes of physicochemical H2S runs at high temperature/high pressure. So, it costs a lot to maintain and it causes the secondary pollutants like Sulfur dioxide or Spent Catalyst. To solve the problem, it is required to develop the high efficiency and low cost technology that the removal efficiency of H2S is excellent and there is little possibility of secondary pollutants. We can consider the technology to remove high concentration of H2S efficiently with a reasonable price using the chemical and biological multiple reactions. The principle of the technology which is applied to this study is to use the chemical catalyst reactions that the Iron-oxide, a by-product of microorganism, acts as the catalyst and removes the H2S using elemental sulfur and also to use the biological reaction that re-oxidizes the catalyst(Catalyzed Reduction type) using T.ferrooxidans of Thiobacillus ferrooxidans and reproduces to catalyst(Oxidation Catalyst type). The reproduction speed of catalyst for Fe is about 22 ～ 40 ㎏-Fe2+/㎥·d which is reported from a variety of studies on the development of technology for various semibatch reactors and continuous cultures using fluidized bed reactor or fixed bed reactor using technology of cell immobilization. And, there are a lot of successful cases for commercialization. But, the domestic study for microbial desulfurization for H2S is in the beginning level also, most of studies are arranged in the small facility like the laboratory so, the estimation skill for the field application is not enough.

Chapt III. Development of high-speed catalyst regenerating desulfurization reaction apparatus. The evaluation results showed that when sustrate's concentration was 9 g/L, the catalyst regeneration velocity was 12 m3/m3·d in the fixaties reactor according to the changing filling amounts. Therefore regeneration amounts had been achieved 10 kg/m3·d as in detailed purpose. Also, resulted from evaluated catalyst generation efficiency which is seperated contineous type process, semi-contineous type process to catalyst-supply process for high-speed catalyst, As maximum velocity from semi-contineous type process came out 62.41 kg·m-3·d-1 under 13 Fe-g/L, 0.4 vvm, 30oC, and maximum velocity from contineous type process to catalyst-supply process came out 62.41 m-3·d-1 under 13 Fe-g/L, 0.2 vvm, It is attain to high regeneration-velocity above 40 kg·m-3·d-1 from prior dissertations's result. Through Catalyst supply velocity effeciency survey following catalyst supply velocity and changing velocity, Construction factor of Reactor fixed Pilot regeneration is able to establish. For eliciting optimum operation condition of the high-speed catalyst regenerating desulfurization reaction apparatus, Resulting in using the reaction apparatus and concentration of Fe-iron under catalyst, reaction time, concentration of inlet, filling form of absorption tower, sprinkling water changing form. etc, When Fe3+ solution is under concentration of 30 g/L, reaction time of 60 sec, H2S's inllet concentration approximately 2,000 ppm, It was verified 99.2% of H2S's removal effeciency, when H2S's inlet concentration was increased 6,000ppm, 9,000 ppm, It was removed 19.44 kg H2S/m3·d, 28.30 kg H2S/m3·d. This achieved exceeding removal effeciency of 99%, 20 kg H2S/m3·d of removal amounts of H2S. In the operation stability researching which is long-term prepared pilot tests of the high-speed catalyst regeneration desulfurization reaction apparatus developed research, It came out removal efficiency which is stabilized for approximately 60-days, The desulfurization by-product (Sㅇ) with sulfide didn't have an influence on regenerating speed. Implantation amounts of the effect additive which reaches in catalyst remaking speed and implantation time is visible 62.39 kg m-3·d-1 under 9 Fe-g/L, 0.4 vvm, 30oC, and 62.41 kg·m-3·d-1 under 13 Fe-g/L, 0.4 vvm, as above, we achieved the exceeding results in compared to the existing study(catalyst regeneration amount 40 kg-Fe/m3·d and regeneration amount of catalyst solution). Chapt IV. Evaluation of Pilot high-speed catalyst of regeneration desulfurization reactor Industry for on-site assessment which is located in Ansan-si Banwol industrial complex treats wastewater of 1,900 ㎥/day generated in fifteen industry(i.e., leather industry for processing raw hide). We have completed design and production of desulfurization facility for handling approximately 2,000 L/min(2㎥/min) air volume equal to real scale. For evaluating on-site performance we have requested analysis to external official institute and drawn design factor of commercialized desulfurization facility with stability of process through enduring operation. Trough this study we know that hydrogen sulfide is removed reliably above 96% after fourty-five operation days and catalyst is regenerated almost perfectly. In addition we can identify that ammonia and amine series, typical odor substance without hydrogen sulfide are removed perfectly such as level of non-detection.

Chapt Ⅴ. Result The results of this study suggest that it is possible to remove high concentration hydrogen sulfide from leather wastewater, environmental facilities, tail-gas of Claus sulfur recovery plants, sour gas of petroleum refineries, coal gasification process. If this method obtains the applicability through a variety case, such as each industrial process design, it is expected to be a more effective method to remove hydrogen sulfide.