# Biodiesel and Biolubricant Production from Waste Cooking Oil: Transesterification Reactor Modeling
## 3 Results and Discussion
### Industrial Equipment, Reactor Design, and Economic Feasibility Study  
Once the kinetic study was carried out, a preliminary design for a small plant to produce biodiesel or biolubricants from WCO was also developed, including an economic feasibility assessment. The main steps are included in Figure 11 as follows:  
One key step is the previous kinetic study, which will determine different factors, like the WCO supply, the selection of the working regime, or the quantities of the reagents. Equally, the working regime will determine the selection and design of different components, especially in the case of the reactor and, equally, the diffe  
Figure 11: Steps carried out for the design of the plant for biolubricant production from WCO, with the corresponding economic feasibility study.  
Figure 10: Dependence of the apparent kinetic constant on the catalyst concentration according to a second-order reaction model.  
place (including heating, reaction, or separation processes). At the same time, the selection and determination of the different processes have an influence on the equipment selected. Finally, the reagent and energy consumption are dependent on the designed facility and the abovementioned steps. These choices were analyzed from an economic perspective, to assess the feasibility of the designed plant.  
5.1 Preliminary Considerations: Site Location, Production Regime, and WCO Processing Capacity of the Plant  
For the location of the plant, a site located in Badajoz (38\({}^{\circ}\)53\({}^{\prime}\)45.0\({}^{\prime\prime}\) N, 6\({}^{\circ}\)59\({}^{\prime}\)36.3\({}^{\prime\prime}\) W) has been selected because of its expansive construction area and advantageous location. It is relevant to mention that although most of the industries in Badajoz are situated in this area, there is currently no industrial plant dedicated to the production of biodiesel or biolubricants in Badajoz, indicating a lack of competition in this sector within this region.  
Another important factor in this choice was the excellent road and rail transportation facilities of the site, which favor the commercialization of the manufactured product.  
To carry out the preliminary design of the industrial plant for this project, it is essential to estimate the availability of the raw material (that is, WCO) in this area. According to a previous study, an average amount of about 4 L of WCO is generated per person each year [61]. With a population of about 150,000 inhabitants, the total amount of WCO generated in this area is estimated to be approximately 600 cubic meters per year. Considering the typical efficiency of the collection system, this amount is reduced to about 460 m\({}^{3}\)/year. Considering the density of the WCO, the design capacity of the plant was set at 48.4 kg WCO-h\({}^{-1}\). As this is not a high capacity, a batch-mode process was selected.  
Thus, a discontinuous regime allows for a work shift regime (8 hours per shift, 5 days per week) with total working hours of 2112 h/year. In detail, Table 5 shows the information related to a working year at the designed plant [37]. Considering the time required for both transesterification reactions, along with the heating of reagents and separation of products observed in further subsections, 8 hours per shift were enough to carry out the whole process.