Basic Research On Technology Of Deamination Of Skin And Ammonia Recovery By High Gravity Method

Skin is from fresh latex after centrifugal separation,as the second product because of its high ammonia content,and there are many defects in the preparation of skin rubber,such as high acid consumption,difficult wastewater treatment and high cost.In order to solve this problem,scientists have proposed to use natural ventilation,aeration,mechanical blast and centrifugal atomization to remove ammonia from the rubber.Although some results have been achieved,there are still some shortcomings,such as low ammonia removal rate,complex process,high energy consumption and difficult recovery.Based on this,the main purpose of this study is to find the high efficiency and easy removal of ammonia gas and to achieve ammonia recovery.High gravity technology is a new technology for process intensification.The liquid is dispersed into filaments,droplets and membranes,which can quickly gather and disperse,and the gas-liquid contact area per unit volume of liquid will be increased,and micro-mixing will be strengthen.In this study,two high-gravity devices were used to achieve high-efficiency deamination and ammonia recovery.In the demineralization system of the skin,the effects of gas flow rate G,raw material ammonia content x_w,liquid temperature T_L,supergravity factor?,feed flow rate L,gas temperature T_G on the deamination performance and mass transfer performance of the rubber paste were investigated.The significant effects of each factor were showed by orthogonal experiments,G>x_w>T_L>?>L>T_G.The single factor experiment showed that under the premise of other operating conditions,the deamination rate?increased with the increase of G,T_L and T_G,and decreased with the increase of L,with the increase of?,first increased and then decreased.The total gas phase volume mass transfer coefficient k_ya_e has the same change rule,and the best operating conditions are obtained:G is 18 m~3/h,?is 69.25,T_L is 55?,L is 20 L/h,and T_G is 55?.Under this condition,when the ammonia content of the raw material is 0.2963%,?can reach 70%after three times of stripping,and the export ammonia content x_D can be reduced to 0.09%,which is in line with industrial application requirements.The equilibrium mass fraction of ammonia in the skid and the total mass fraction of ammonia in the rubber particles were calculated to be 0.082%,which indicated that the deamination effect of the process in this study was close to the limit state,and the deamination rate was very high.The mathematical model of the influence of various influencing factors on the deamination rate in the de-ammonia process of high-gravity gelatin was established based on the dimensionless analysis method.The correlation coefficient R~2 was greater than 0.95,the maximum deviation was 9.72%,and the average deviation was 4.88%,which showed that the calculated value is basically consistent with the experimental data.In the deamination process of the skin,the pressure drop performance of the rotating packed bed was studied.The results showed that the gas pressure drop increased with the increase of gas flow rate and high gravity factor,and changeless with the increase of liquid flow rate,obviously.In this experiment,the gas pressure drop ranges from 10 to 25 Pa.In the ammonia recovery system,the effects of the liquid circulation amount S,the high gravity factor?',and the liquid flow rate L'on the ammonia absorption rate?were investigated.Orthogonal experiments showed that the significant effects of each factor were S>?'>L'.The single factor experiment showed that under the premise of other operating conditions,the absorption rate?increased with the increase of S and L',and increased first and then remain unchanged with the increase of?'.The absorption rate can reach 98.71%under the S of 11,?'of 69.25,L'of 120.The recovered ammonia gas can be used for fresh gum preservation or other processes to achieve the purpose of resource saving and environmental protection.Through the calculation of ammonia removal efficiency and benefit,it is found that this process has a remarkable effect in ammonia from the plastic clearing process.Compared with the characteristic parameters of deamination rate,the high gravity method is 1.94 times of the aeration method and 1.17 times of the centrifugal atomization method.In addition,the acid residue treated by the high gravity equipment can save 891.216 kg of acid per day.It is 2.063times of the aeration method and 1.4 times that of the centrifugal atomization method.Compared with the traditional rubber deamination method,the super gravity method has the advantages of high deamination rate,simple operation,small equipment volume,and easy ammonia recovery.The comprehensive research results showed that the process of ammonia removal from skin by high-gravity method is more suitable for industrialization.