Zeolite-organic Mixture For Removal Of Water
Zeolite-organic MIXTURE FOR removal of WATER
from NATURE GAS and LIQUID HYDROCARBONS
G.T. Sitkarov, D.I. Shvets
Institute for Sorption and Endoecology Problems, Ukrainian National Academy of Sciences, General Naumov st. 13, 03680, Kyiv-164, Ukraine,
e-mail: dshvets@ispe.kiev.ua
Increasing amount of transport in Ukraine has recently tended to increase of harmful exhausts from transport means that is caused, first of all, by poor quality of fuel. Because of this, the search of a new method for fuel purification both from harmful admixtures and water are required to decrease of exhausts and to improve ecological situation, especially in large cities. The sorbents and sorption methods with use of cheap and accessible sorbents are the most perspective in this plan, as they allow to provide a high extent of purification at low expenditures of energy.
In this connection the search of new methods of dehydration liquid and hydrocarbons gas is carried out on the basis of study of take-up of water by most strong adsorbents and accessible to practical applying (for example, natural zeolites) and absorbents (for example, liquid glycols). One of perspective directions of drying is combined systems applying on the basis of natural sorbents. Therefore the work presents the results of a combined system "natural zeolite + diethylene-glycol" properties for drying nature gas from a moisture study.
The studies of zeolite-organic system "zeolite + water + diethylene-glycol" on take-up of water in this system have shown, that the process can be divided into two stages: the first – before complete saturating natural zeolite with water (the maximal adsorption of water is 0,20-0,25 g/g) and the second – after saturating zeolite with water.
At the first stage water displaces adsorbed molecules of diethylene glycol (DEG) placed on the surface and in porous space of zeolite, thus with a raise of relative content of water in a system the amount of water adsorbed by zeolite was augmented and the amount of DEG adsorbed by zeolite was moderated, hence, at the second stage the adsorption of DEG was not practically observed.
The results of studies of this zeolite-organic system have allowed to propose a new method of drying of nature gas from water vapor on the basis of applying combined sorbent as zeoliteorganic mixture. At the proposed method, natural gas is continuously skipped through starting solution DEG (96-98 %) and simultaneously through the layer of natural zeolite (klinoptilolite) contacting to the same solution. The presence of contact of zeolite with solution of DEG results in continuous and preferred water sorbing by zeolite from this solution and to expulsion of DEG by water from zeolite pores. These processes lower percentage of water in solution of DEG and due to this, support high activity of DEG on take-up of waters from nature gas. The proposed method allows in some time to diminish the used bulk of DEG in comparison with the applied method (through colliding and continuous forced-circulation of nature gas by diethylene glycol) and provides demanded quality of drying.
The influencing of a fraction size of natural zeolite on process of drying of nature gas is studied. The size of a fraction of 3-5 mm is recommended, allowing the negative factors: at smaller sizes (up to 2 mm) the bloating of klinoptilolite took place at extraction of water and dimness of solution, and at larger sizes (more than 5 mm) the adsorption of water was decreased and expenditure of energy on its regeneration grew more essentially.
The expediency of such method is determined also by the fact that diethylene glycol is expensive absorbent, it is imported to Ukraine, production of granulated synthetic zeolite practically absent, and there are major resources of natural zeolites for example, in Carpathian.
The carried out experimental studies have allowed also to propose effective and mobile for realization method of removal of the water from liquid hydrocarbons, which have less density, than water, with use of liquid glycol as a fissile absorbant of water.
The carrying out of further works on making pilot plants for checkout of the proposed methods and for definition of rational parameters of industrial modular devices is planed.
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