New perforated plate for chemical industries
FGUSAL/DICYT Researchers at the University of Salamanca have developed a new design for perforated plates. Metal plates with holes that are usually integrated in the facilities of various chemical industries specialised in compounds separation processes, such as distillation and absorption. Through a proof of concept, scientists have demonstrated experimentally that the model they propose is more efficient than conventional dishes.
"Those plates normally consist of a circular section in which orifices are arranged in a certain number, with a given diameter and with a certain distribution" explains Elena Díaz Martín researcher at the Department of Chemical and Textile Engineering, " They are widely used for the separation of compounds in which maximizing mass transfer between two phases is required, as occur between a liquid phase and a gas phase. The metal dish serves as a gas distributor and its performance as distributor will determine its quality.
Mass transfer operations involving the gaseous and liquid phases are very common, such as distillation, a process which separates substances in a liquid mixture by vaporization and condensation; This process is widely use in many chemical plants. "When compounds separation is required, distillation is the first option", remarks the expert.
However, absorption is also very important, especially for the treatment of contaminating gases. This operation consists of separating the components of a gaseous mixture. On this occasion, proof of concept has been based, precisely, on this process. In any case, the industries in which these dishes can be used vary widely, from petrochemical to pharmaceutical, or even food companies.
The plates favor the contact between the gas and the liquid, "but their efficiency is low", states Elena Diaz. One of the parameters defining the plate is the distribution of the holes, which are generally arranged in a square or triangular shape. That is why "we propose a new holes distribution to improve mass transfer efficiency" she recalls.
The aim of this project has been to verify experimentally that the level of efficiency of this new distribution is greater than the one accomplished by traditional dishes. To do this, "we have used an absorption column with air and water," says Marina Terleira Fernández, also a project researcher. "The oxygen in the water is displaced with a stream of nitrogen, and then we measure the oxygen transfer from the gas phase to the liquid phase," she explains.
In order to evaluate efficiency improvements, two parameters are taken into account: the gas retention in the column and the mass transfer rate. Thus, researchers have determined that the new dish improves it s performance by 5%. However, "we are talking about the efficiency of just one dish, but in industrial towers they normally use 20 to 30 plates, therefore, the efficiency would accumulate from plate to plate, considerably raising the total improvement" she highlights.
The project has been developed thanks to the Proof of Concept call from the General Foundation of the University of Salamanca and within TCUE programme from Junta de Castilla y León, along with FEDER funds co-financing. After demonstrating that the design of the new dish offers better results, researchers will continue on its way to until the innovation will be implemented by the industry.