Development Of Ultrasonic Assisted Ultrafiltration Desalination Process And Equipment For Salted Duck Egg White

Salted duck egg is a traditional delicacy in China.It is widely loved because of its good taste and flavor.Every year on the Dragon Boat Festival and Mid-Autumn Festival,a large number of salted egg yolks are used to make zongzi and moon cakes.Most of the remaining salted egg whites are abandoned because of their high salt content.It not only wastes protein,but also pollutes the environment.Desalination of salted egg white can effectively reduce the salt content in salted egg white and recover high-quality protein.In order to realize the industrialized desalination of salted egg white,it is necessary to develop the desalination device of salted egg white.This paper designs a salted egg white desalination device,which combines the ultrasonic assisted salted egg white ultrafiltration desalination process,and develops a control system to realize the automatic and efficient desalination of salted egg white through PC(computer),which provides a basis for the recycling of salted egg white in enterprises.The main contents of this paper include three parts:the research on the desalination process conditions of salted egg white,the development of desalination device and control system,and the optimization and verification of the desalination effect of the prototype.The specific contents are as follows.(1)The optimum desalination process and parameters of salted egg white were studied.Firstly,according to the desalination technology of salted egg white and the actual industrial production,the ultrafiltration desalination method of salted egg white is selected.The influence of ultrasonic effect on protein and salt in salty egg white was analyzed.Combined with the two most important indexes of operating pressure and dilution ratio in ultrafiltration desalination method,the ultrasonic assisted salty egg white ultrafiltration desalination process with three factors of ultrasonic power,operating pressure and dilution ratio as parameters was determined.Through the experiment,it is determined that the intermittent constant volume desalination volume and desalination times are 1L and 3 times respectively,which have the least impact on the desalination efficiency.Taking the membrane flux as the index,the necessity of cleaning the device is designed and analyzed,and it is concluded that the cleaning device has the least membrane pollution after desalting for 3 times.Then,taking the membrane flux as the index,a single factor experiment was designed to study the effects of ultrasonic power,dilution ratio and operating pressure on salted egg white.The results show that the membrane flux increases with the increase of ultrasonic power;When the operating pressure is within 0.2MPa,the optimum operating pressure is,the optimum the membrane flux is;When the dilution ratio is less than 3 times,the dilution ratio increases and the membrane flux increases.When the dilution ratio is greater than 3 times,the dilution ratio increases and the membrane flux decreases.Finally,based on the single factor experiment,a three factor and three-level orthogonal optimization experiment was designed.The results showed that the order of the influence of the three factors on the desalination efficiency of salted egg white was operating pressure,dilution multiple and ultrasonic power;The optimum desalination process parameters are operating pressure 0.2MPa,dilution multiple 3 times and ultrasonic power 600W.Under these conditions,the desalination rate of salted egg white is 83.76%and the protein recovery rate is 76.56%.(2)The equipment of ultrasonic assisted ultrafiltration desalination of salted egg white was developed.According to the requirements and control points of ultrasonic assisted salty egg white ultrafiltration desalination process,the overall scheme of ultrasonic assisted salty egg white ultrafiltration desalination is designed from two aspects of mechanical device and control system.Firstly,according to the demand,a device is designed to realize the switching between forward desalination and reverse recovery flushing through different valve combinations;The forward circuit can realize the desalination function,and the reverse circuit can wash and recover the residual egg white on the pipeline and membrane.Secondly,the lower computer controller,expansion module and sensor are selected.Allocate the I\O port of PLC according to the control points.STEP 7 Micro WIN software is used to assemble the conductor diagram program,design the system flow program and realize the basic control function.Then the main interface,parametric interface,login interface and alarm interface are designed with Win CC,and PC access software is used to complete the communication between Win CC and PLC,so as to realize the control of hardware state.Finally,the development of the equipment is completed,and the automatic desalination of salted egg white is realized through PC control.(3)Prototype optimization and verification.Firstly,in order to realize the accurate measurement of salt content of salted egg white,the relationship between conductivity and salt content of salted egg white was obtained by univariate linear regression analysis.The results show that the determination coefficient R~2 is 0.995693,and there is a strong positive correlation between conductivity and salt content;Significance F is close to 0,and the relationship between them is significant;The P-value is much less than 0.05,and the coefficient of regression equation is significant.Then,taking the membrane flux as the index,the effects of the ultrafiltration device prototype designed in this study and the preliminary test RNM-UF-1 device are compared.The results show that the prototype can effectively slow down the membrane pollution rate,improve the desalination efficiency and increase the service life of the membrane.Under the optimum desalination process parameters,the desalination rate of the prototype is 85.40%,the protein recovery rate is77%,the desalination rate is improved,and the change of protein recovery rate is small.The prototype solves the problem of membrane pollution in ultrafiltration desalination of salted egg white,improves the desalination efficiency and effect through back flushing and control system,and can meet the requirements of industrialized production of salted egg white desalination.