Pyrolysis Products Characteristic Of Dianchi Lake Sediment And Desulfurization Performance Of Dianchi Lake Sediment Supported Catalyst

Both the exogenous and endogenous management of Dianchi Lake produce sludge. There are more than 8 wastewater treatment plants in Dianchi basin. They produce 316.7 ton thousands sludge every year. The estimate amount of sediment on the Dianchi lake bed is about 80 million to 120 million cubes. Dredging Project of Dianchi Lake has already dig up sludge more than 10 million cubes. The sludge treatments have important relationship with Dianchi lake comprehensive control. Dianchi Lake sediment was abundant in fixed carbon and hydrogen isotope. The calorific value of sludge was range from 7 to 10 MJ/kg without water in the dry condition. Obviously, the cal & rific value was corresponded with lignitous coal, his characteristics decide it will have high value of development and utiliztion. Most of the dredged sediment is stacked on the shore of Dianchi Lake, which not only takes up a lot of land, but also may leads to secondary pollution. In order to reach the purpose of dispose the Dianchi Lake sediment and recovery the energy, we will adopt the technology of pyrolysis with catalytic to pyrolysis the Dianchi Lake sediment.In the processing of pyrolysis, the pyrolysis oil, water, non-condensable gases and solid will obtained. In a manner of speaking, the pyrolysis oil can consider as high-value energy to utilization, solid substances will preparation for absorbent materials and gaseous products can be used as the fuel gas. At the same time,Municipal wastewater treatment plant sludge containing N, P and organic plant growth nutrients needed, Sludge in agriculture can significantly improve the physical and chemical properties of the soil, Sludge processed through the appropriate modified, Sludge mixed soil is able to satisfy the requirements of the Plant Growth, Mainly in the following areas of research:(1) TG-DTA experiment of the sediment from Dianchi Lake was carried out in the air atmosphere, the results show that the combustion of the sediment from Dianchi Lake sediments can be divided into four stages. The kinetic calculation results of TG curves indicate that the second stage (230℃～420℃) is a first order reaction, with 22.7kJ/mol for activation energy, and the third stage (421℃～530℃) is a second order reaction, with 15.4kJ/mol for activation energy.(2) Using a fixed bed reactor to study the pyrolysis mechanism of Dianchi Lake sediment, explorering the impact of pyrolysis process at the range of 500～1000 ℃ different pyrolysis temperature, indicating that Solid pyrolysis product yield with the pyrolysis temperature increases, the reduction rate decreases with increasing temperature, The volatile removal occurs mainly in the relatively low temperature of 500～700 ℃ segment Sediment of Dianchi Lake, With the final pyrolysis temperature increases, the liquid product yield first increases and then decreases, When the temperature is higher than 600 ℃, Liquid pyrolysis products of secondary cracking reactions gradually strengthen, Resulting in decreased yield of liquid product. Yield of pyrolysis and gasification with pyrolysis final temperature rise gradually increase.(3) Dianchi Lake sediment carrier was developed and used to catalytic hydrolysis of CS2:Carrier was prepared with pyrolysis solid product from sediment of Dianchi Lake. Dianchi lake sediment carrier would be prepared through two steps of carbonization and activation, and the activating agent was ZnCl2. The influences of carbonization temperatures, activating agent contents, activation temperatures on catalytic hydrolysis activity were studied. The results show that the optimal carbonization condition is 600 ℃, 60min; the optimal activating agent/sediment carrier (mass ratio) is 2:1; the optimal activation condition is 600 ℃,60min.(4) Studies on modification and desulfurization performance of Tien lake sediment activated carbon supported catalyst:In order to further improve the desulfurization performance of Dianchi lake sediment supported catalyst, the catalyst was modified. In this study, the effect of supported metal species, supported metal content, calcination temperature, dipping alkali species and dipping alkali content were investigated. The optimal modification conditions were determined by the above studies on effect of factors for CS2 catalytic hydrolysis efficiency. The studies shown that the catalyst had the optimum desulfurization performance when the supported metal species and content, calcination temperature and time, dipping alkali species and content were Fe2O3 and 10%,500℃ and 3 h, KOH and 10%, respectively. Based on the optimum preparation conditions were determined, the effect of reaction temperature, oxygen content, gas hourly space velocity, relative humidity and inlet CS2 concentration on CS2 removal efficiency were investigated. The studies showed that the CS2 removal efficiency first increased and then decreased with the increase of reaction temperature and relative humidity. The excess high reaction temperature and relative humidity promoted the faster generation of H2S, which was not beneficial to the catalytic hydrolysis reaction. The introduction of a small amount of O2 was beneficial to improve the catalytic activity. On the contrary, the excess O2 content promoted the excess generation of sulfate, which decreased the catalytic hydrolysis activity. The CS2 catalytic hydrolysis activity gradually decreased with the increase of inlet CS2 concentration.(5) It is a systematic research on the regeneration of exhausted catalysts. The results showed that water scrubbing+N2 calcinations purging+alkaline regeneration method was the best one, and the N2 calcinations purging temperature was 500— for 2h, the KOH content was 13%. First, a small quantity of S/sulfate on the exhausted catalyst’s surface could be removed with the "water scrubbing" process; parts of sulfate could be decomposed to SO2 in the process of "N2 calcinations purging", active component Fe2O3 on the catalyst’s surface could be recovered, "alkaline regeneration" could provide the alkaline groups for catalytic hydrolysis reaction. After regenerating by this way, the catalyst was close to the fresh catalyst, so the recovery of catalytic hydrolysis activity was the most obvious. Besides, this regeneration method was feasible and good stability.(6) The reaction kinetics of catalytic hydrolysis of CS2Over catalyst was calculated and analysed. The reaction kinetics of CS2 catalytic hydrolysis were analyzed and fitted respectively by power function dynamic equivalent model. The reaction kinetics equation of CS2 catalytic hydrolysis was obtained:-rA=2.721exp(2.824/(RT))CCS21.000007CHH2O-0.000008Based on the XPS result, the reaction mechanism of CS2 hydrolysis over catalyst was proposed. There were two steps on the surface of catalyst in the reaction process: hydrolysis of CS2 process and oxidation of H2S from the hydrolysis. The rate of CS2 adsoption was the control step of CS2 hydrolysis. The adsorptive CS2 was continuously hydrolysised to H2S on the active center with the reaction and the H2S was oxidized to elemental sulfur and sulfate on the oxidation center finally.