| In order to increase pulp yield,improve pulp quality,reduce chemical use,reduce energy consumption,and reduce environmental pollution,extended delignification technology has emerged.Many improved and innovative cooking technologies developed from extended delignification technology have been relatively widely used in the industry,but there are few such devices in the laboratory.So extended delignification technology cannot be further explored in the laboratory.Therefore,based on the theory of extended delignification,a multi-functional multi-phase step-reaction apparatus is designed to achieve this goal.Using Eucalyptus urophylla as raw material,a multi-functional multi-phase step-reaction apparatus is applied to preliminary exploration of the kraft process.In this paper,the main conclusions are as follows:1.A structure of a multi-functional multi-phase step-reaction apparatus is studied and designed.The structure is in accordance with the replacement or mixing requirements of the cooking process,meeting the requirements of temperature,pressure,and corrosion resistance,and capable of on-line detection of temperature,pressure,flow,and the requirements of automation control.2.The automatic control system of multi-functional multi-phase step-reaction apparatus is studied and designed.The system built by PLC and MCGS includes the main control program and human-machine interaction interface.The main control program is the sequential control of the process,the constant temperature control of the reactor,and the collection and feedback of relevant data;the human-machine interaction interface mainly completes the live display of data such as temperature,pressure,and flow,as well as the manual operation of the process control.3.Gaussian fitting method is used to obtain the relative reaction rate constant curve.Through the system's high frequency acquisition of temperature data,an on-line calculation system of H-factor is established.It has been verified that compared with the traditional H-factor calculation method,the error in the heating-up stage reduced by 11%,the error of total H-factor reduced by 1.32%;in experimental application analysis,the error of total H-factor reduced by 2.09%,effectively improving the ability of the H-factor to control the quality of the pulp.4.In the multi-functional multi-phase step-reaction apparatus and M/K digester,the Eucalyptus urophylla kraft step reaction is used for cooking,and by adjusting the conventional cooking process conditions.The step-reaction cooking process was divided into three stages.The cooking liquor concentrations were sodium sulfide which concentrations were 13.59 g/L,6.29 g/L,0 g/L and sodium hydroxide which concentrations were 9.29 g/L,19.35 g/L,and 20.65 g/L respectively.The temperature were 90-120?,120-150? and 150-168? respectively,and the holding time is 30.45 and 75 min.The obtained pulp yield is 45.64%,the Kappa number is 10.15,the viscosity is 1057.3 mL·g-1 and material whiteness is 27.41%ISO.The conventional kraft cooking process conditions of Eucalyptus urophylla get the pulp yield 45.89%,Kappa number 17.51,viscosity 798 mL·g-1 and pulp whiteness 21.30%ISO.It can be seen that,in the case of a difference of 0.25%in the pulp yield,the Kappa number of the step-reaction cooking process is reduced by 42.03%the viscosity is increased by 32.49%and the whiteness is increased by 28.69%.5.Compared with the conventional kraft cooking process,the kraft step-reaction cooking process of Eucalyptus urophylla significantly improve the pulp properities when the pulp yield is reduced by about 0.25%.The physical properties of the two,tear index,burst index,tensile index,bending degree,there is no significant difference,but a slight increase.Therefore,the kraft step-reaction cooking process of Eucalyptus urophylla can be further adjusted in the later period of study to improve the pulp yield and pulp physical properties.6.It can be seen from the experimental application of the segment kraft cooking of Eucalyptus urophylla.The multi-functional multi-phase step-reaction apparatus has the ability to conduct Extended delignification technology exploration,and can realize the automatic control of the reaction device and control the operation and monitor of the process. |
PDF Full Text Request