Conceptual Design Of MSSAQ Pulping Process Integrated Chemical Looping Combustion And Its Heat-water Network Optimization

Pulpmaking is a high-energy-consumption process,which obtains its energy from coal and black liquor.Generally,coal and black liquor are combusted in boiler,which is low efficiency and high emission.It's significant to impove energy efficiency of pulp industry in a clean and low-cost way.Coal and biomass gasification technic play an important role in clean production and high energy efficiency,and the pulp technic that corporate with black liquor gasification well is Mini-Sulfide Sulfite Anthraquinone?MSSAQ?,which has many advantages over kraft pulping.However,the investment of MSSAQ pulping is way more than kraft pulping,which makes it uneconomic.Based on existing MSSAQ pulping process,this research proposes to integrate chemical looping combustion?CLC?into MSSAQ pulping.Since CLC has the capability to saperate carbon dioxide and sulfur dioxide,the carbon escape while combustion is captched easily,also it's clean and low-cost way to improve energy use from coal and black liquor.Aspen Plus is used to simulate the process units.Energy efficiency,carbon emission and techno-economic analysis are deployed according to simulation results.Enhanced adaptive differential evolution algorithm is proposed to raise a solution of heat-integrated water network optimization problem in pulp mill to further optimized water use and heat recovery.Finally,sensitive analysis of hyper-parameters in enhanced adaptive differential evolution algorithm is given to convice the optimization result.According to simulation results,CLC unit gives the best proformance when the pressure is set to 2.5 MPa,the mole flow rate of oxygen carrier is 50 kmol for each tonne of dry pulp production,the reducer runs in 900?and the oxidixer runs in 850?.The energy efficiency of CLC-BLG-MSSAQ pulping is 25%and 11.3%more than kraft and BLG-MSSAQ respectively.Besides,CLC-BLG-MSSAQ pulping cuts the investment on flue gas treatment by eighty to ninety percent by reducing 0.62 tonne and 0.17 tonne carbon emission compared to kraft and BLG-MSSAQ pulping respectively.Finally,under the scenario of US0/tCO₂e and US20/tCO₂e,CLC-BLG-MSSAQ pulping process is not cost-efficient compares to kraft pulping process.But under the scenario of US40/tCO₂e and US60/tCO₂e,CLC-BLG-MSSAQ pulping process cost 8.8×10⁸/year and 8.8×10⁸/year,which 37%and 42%less than kraft and BLG-MSSAQ pulping process respectively.According to heat-integrated water network optimization results,for each tonne of dry pulp production,the cost of fresh water,utility and fixed capital is 56.1 CNY,221.8 CNY,32.47CNY,respectively.The total energy that can be recovered is 7.5GJ.Compare to the original proposal,46.6%of the operation cost is saved.