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Raw hide, being an expensive starting material for manufacturing natural leathers, arrives in tanneries in a preserved state. In most cases, sodium chloride is used as preservation medium. In a whole number of operations through which raw hide is transformed into leather, raw hide desalting is a very important operation in view of final quality. Th...
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Context 1
... dissolving of salt, dissociation into Na + cations and Cl -anions takes place, making possible the conduction of current. Conductivity of the solution of produced electrolyte is dependent on ionic concentration, charge magnitude of individual ions, on solution temperature and mobility of Table 1 and depicted in Fig. 1. The dissolving rate constant was found by measuring changes in conductivity and, thereby, also changes in concentration of salt in solution dependently on time. ...
Citations
... There are very few reports on the use of theoretical tools of chemical engineering for optimization of the real technological deliming procedure on industrial scale, especially form the viewpoint of the implementation of transport phenomena theory describing diffusion of low-molecular substances in natural polymers [5,6,7]. ...
The paper deals with optimization of the calcimine deliming process during production of food grade gelatin. This process is the most important step from chemical engineering and environmental protection standpoint during production of food gelatin. The main objective of the paper is to provide a suitable mathematical description of the chemical deliming process. The proposed model is subsequently used for optimization of the deliming process to minimize the operating costs and environmental burden. The experimental part follows two main aims: determination of the effective diffusion coefficient of calcium sulfate during deliming with ammonium sulfate based on experimentally measured data, and computer simulations of the operating costs from the viewpoint of various soaking numbers, degree of the deliming and strength of the
bond of calcium hydroxide to collagen. The results give ground for further optimization and exact transfer of laboratory data into real industrial operations.
... Modern approach to optimization is application of theoretical tools of chemical engineering, i.e. mathematical modeling of the physical-chemical processes [3]. Detailed description of transport phenomena related to NaCl diffusion in the hides is available only for soaking. ...
Diffusion of sodium chloride plays key role in the pre-tanning treatment of raw hides, namely in the brine curing and soaking operations. Understanding the transport processes related to these operations gives ground for their optimization and thus to reduction of the adverse environmental impact as well as minimization of the consumption of sodium chloride, water and energies. Mathematical model of raw hide curing is presented and its modification for spherical coordinates applied on the description of the desalting of fleshings, a cheap raw material for the production of biodiesel and high quality gelatin. Desalting is the key step in the fleshings complex processing and the quality of the resulting products is highly dependent on the precise performance of the desalting operation. The experimental part includes determination of the effective diffusion coefficient of NaCl during brine curing on
model porous material using color indication of the border area, determination of the diffusion coefficient of NaCl in the inner volume of fleshing during desalting, and pilot scale testing of the efficiency of fleshings desalting. The obtained diffusion coefficients were compared with the theoretical value at infinite dilution and factors affecting the diffusion coefficient values were discussed.
... For the purposes of our study, we proceeded particularly from the mathematical description of chemical-physical processes taking place in the fleshing material. Transport phenomena connected to collagen material desalting are described e.g. in [15,16]. The desalting process is not part of our contribution; however, it is applied to fleshings coming from cured hides prior to the processes described below. ...
Waste fat produced by tanneries during the processes in which raw hide is transformed into leather represents a very important raw material for biodiesel production. However, the acid number of this feedstock is usually high above the limit 1 mg KOH/g, which makes it unsuitable for direct processing into biodiesel via
alkali-catalyzed transesterification. An effective and economically viable pre-treatment method is needed to overcome this disadvantage and at the same time to maintain the advantage of low price of the feedstock. In this paper, we present a pre-treatment method consisting of the refining melting and deacidification steps. The pretreatment processes are part of a complex technology for biodiesel production from low quality fats and oils. Mathematical models of the said processes have been elaborated for the optimization of the
pre-treatment procedure, as well as a software application developed for simulation of the deacidification step. Suitability and economic parameters of the pre-treatment technology for feedstocks with various free fatty acid content is discussed. Finally, the waste tannery fat potential in biodiesel production is briefly evaluated from the economic and raw material base point of view.
... Equation (1) (3) shows the initial distribution of calcium ions concentration in solid phase-pelt. Relation (4) describes that we use pure water for pelt bath washing. ...
The contribution deals with a certain mathematic model of pelt washing by water in the flow system with retention which is an important part of a leather process. In the process the raw hide is changed into a leather. The process is extremely demanding of sources, especially the water, electric power and chemical agents. The requirements for environmental protection confirm the necessity of making use of possibilities of mathematical modelling by the help of computer algebraic system for optimization and controlling of the process. Keywords Mathematic model, flow washing of pelt, calcium hydroxide concentration field, deliming of pelt, computer algebraic system.
Many technological processes are characterized by large consumption of water, electrical energy and auxiliary chemicals. No even the tanning industry is the exception. The contemporary worldwide trend is an application of the cleaner production principles, which means to take the line of savings and minimization of waste production. It is necessary to deal with the optimization of processes. Within the optimization of the white hide deliming operation, both plain washing with pure water and chemical processing are concerned. The main goal is to give the answer to when it is suitable to interrupt the washing with pure water (nonchemical deliming) and replace it by washing with a deliming agent water solution (chemical deliming). Our paper, with the use of a mathematical-physical process model, gives the answer to the above mentioned question. The effective diffusion coefficients are presented. The above mentioned parameters, economical and technological serve as input data for a computer program and the proposal of automatics control algorithm.
The paper contents the optimization of the washing processes which are characterized by large consumption of washing liquid and electrical energy mainly. For this reason is very important deal with them. For the optimization process of washing it is possible to set up an access of the indirect modeling that is based on make-up of mathematical models coming out of study of the physical operation mechanism. The process is diffusion character it is characterized by the value of diffusion effective coefficient and so called structure power of the removing item to the solid material. The mentioned parameters belong to input data that are important for the automatic control of washing process.
The paper deals with application of computer controlling and displaying system of the technological recycling process of both liquid and solid wastes from the tanning industry. The chrome tannery wastes are potentially dangerous to the environment. A proposal for chrome recycling technology, realization of the laboratory equipment and programming possibility are likewise presented. The idea of recycling technology lies in using reaction of non - environmentally friendly chrome liquid and solid wastes and creating new products that are not toxic and can be used in the other industrial applications. Described mathematical model for the recycling technology is based on the chemical - physical engineering description of a heterogeneous kinetics. The method of regressive analysis was used for determining of parameters for each kinetic equation from the experimental data. The proposed model was used for a simulation test and an optimum calculation in the connection with minimum procedural costs of recycling technology. The real process presentations are built with laboratory equipment for a closed recycling technology of real chrome liquid and solid wastes taken from the tanning company TAREX. The computer controlling and displaying system has two levels. The technological level is composed on a PC with the technological extension card Advantech PCL-812PG ensuring the direct control over the real process. The software for this level was created in the C language with the real time library RTMON. The supervisory level creates a personal computer with professional displaying software by Wonderware InTouch. The parts of software are DDE server module ensuring the communication between both levels of the control system via the serial link RS 232.
Many technological processes are characterized by large consumption of water, electrical energy and auxiliary chemicals. No even the tanning industry is the exception. The contemporary worldwide trend is an application of the cleaner production principles, which means to take the line of savings and minimization of waste production. It is necessary to deal with the optimization of processes.Within the optimization of the white hide deliming operation, both plain washing with pure water and chemical processing are concerned. The main goal is to give the answer to when it is suitable to interrupt the washing with pure water (non-chemical deliming) and replace it by washing with a deliming agent water solution (chemical deliming). Our paper, with the use of a mathematical-physical process model, gives the answer to the above mentioned question. The effective diffusion coefficients are presented. The above mentioned parameters, economical and technological serve as input data for a computer program and the proposal of automatics control algorithm.
The paper is focused on analysis, mathematical modelling and simulation of reactors which are used in the chemical and tanning technology. Material and energy balances are the key issues of mathematical models of chemical reactors and processes. The combination with chemical kinetics and transport effects an intellectual basis for chemical reactor design can be obtained. The contribution brings a special tanning facility – paddle tumbler which can be described as a type of rotary batch reactor and continuous-flow circulation reactor for the cyclohexane production. A mathematical dynamic model is derived and the optimal parameters were computed.
