HRP20220213B1 - A system for saturating liquids with gas and a method for saturating liquids with gas using this system - Google Patents

Abstract

The subject of the invention is a system for saturating liquid with gas, which consists of a liquid source (3), a gas source (5), a gas dissolution chamber (1) and a container for receiving liquid (4), whereby the liquid source (3) is connected via a pipeline (11) equipped with a pump (8) with a cavitation system (14), which is connected via a pipeline (16) to a gas dissolution chamber (1), the end of the pipeline (16) being a set of spray nozzles (7) located in the gas melting chamber (1) to which the gas source (5) is connected via a gas line (10) with a nozzle (6); and the gas dissolution chamber (1) is connected via a pipeline (12) with a control valve (9) to a retention chamber (2) with alternately arranged, partially open partitions (17), which is connected via a pipeline (13) with a valve (15) ), connected to the container for receiving the saturated liquid (4). at least 4 bar, through the pipeline (11), into the cavitation system (14) where the liquid is saturated with gas in the form of micro-nano bubbles and then through the pipeline (10) it is pumped into a set of spray nozzles (7) by means of which the liquid is dispersed in gas dissolution chamber (1), where the liquid is additionally saturated with gas coming from the gas source (5) through the gas line (10) and the nozzle (6), where the supplied gas has a pressure equal to the pressure of the liquid, and then through the pipeline (12 ) the liquid is pumped into the retention chamber (2) through which it flows in a time not shorter than 13 minutes and at a linear speed not exceeding 0.5 m/s necessary for dissolving the gas, after which it is pumped through the pipeline (13) into the receiving tank liquids (4). The subject of the invention is a liquid with gas saturation system comprising of a liquid source (3), a gas source (5), a gas dissolution chamber (1) and a liquid receiving tank (4), where the liquid source (3) is connected by means of a pipeline (11) equipped in the pump (8) with the cavitation system (14) which is connected via a pipeline (16) to the gas dissolution chamber (1), where the end of the pipeline (16) is a set of atomizing nozzles (7) located in the gas dissolution chamber (1) to which a gas source (5) is connected via a gas pipeline (10) with a nozzle (6); and the gas dissolution chamber (1) by means of a pipeline (12) with a control valve (9) is connected to a retention chamber (2) with alternately arranged, partially open partitions (17), which via a pipeline (13) with a valve (15) is connected to the saturated liquid receiving tank (4).<BR/><BR/>The method of saturating the liquid with gas using the above system, where the liquid from the liquid source (3) is pumped by means of a pump (8), raising the liquid pressure to at least 4 bar, through the pipeline (11), to the cavitation system (14) where liquid is saturated with the gas in the form of micro-nano bubbles and then through a pipeline (10) it is pumped into a set of atomizing nozzles (7) with the help of which the liquid is sprayed in the gas dissolution chamber (1), where the liquid is additionally saturated with gas coming from a gas source (5) fed via the gas pipeline (10) and nozzle (6), where the gas is supplied with a pressure equal to the liquid pressure, then via the pipeline (12) the liquid is pumped into the retention chamber (2) through which it flows in not less than 13 minutes and the line speed not exceeding 0.5 m/s necessary to dissolve the gas is then pumped through the pipeline (13) to the liquid receiving tank (4).

Description

The subject of the invention is a system for saturating liquids with gas and a method for saturating liquids with gas.

The invention relates to the field of water purification techniques and waste water purification techniques.

In the state of the art, there are known devices and procedures for saturating liquids with gas. Etchepare R., Oliveira H., Nicknig M., Azevedo A., Rubio J. (2017). Nanobubbles: Generation using a multiphase pump, properties and features in flotation. Mineral Engineering, 2017 (Volume 112), p. 19-26. In their solution, the authors used a saturation pump to produce a compressed mixture of water and air and then expanded it to create nano bubbles of air. This solution is based on air suction under atmospheric pressure and mixing with water in a liquid state. The solution according to the invention ensures the introduction of gas at an absolute pressure of 4 bar and the atomization of the saturated liquid, which enables the creation of a significant contact surface of the phases, which results in a high efficiency of the process.

B.J. Vinci, B.J. Watten, M.B. Timmons, (1995). Modeled gas transport in the oxygen absorber of a spray tower. Aquaculture Engineering, Volume 16, Numbers 1-2, 1997. In their work, they use nozzles to spray water in a column into which oxygen is supplied. The problem of clogging of the spray nozzle with solid particles has not been solved by the author. In case of using an impure liquid, the nozzle of the sprayer will be easily clogged, which will lead to an increase in the failure rate of the device. In the solution according to the invention, the nozzles are equipped with static grinding inserts that significantly reduce the risk of clogging of the nozzles. Also, using the sprayer will ensure the highest possible atomization of the supplied water.

S. Nazari, S.Z. Shafaei, B. Shahbazi, S. Chehreh Chelgani, (2018). A study of the relationship between flotation variables and separation of coarse particles in the absence and presence of nanobubbles. Colloids and surfaces A: Physico-chemical and engineering aspects. Volume 559, 2018, p. 284-288. In the presented solution, the authors introduce compressed air into the water, mixing takes place in two static mixers, then the mixture of water and air is directed to a venturi tube, where, as a result of hydrodynamic cavitation, nano-bubbles are formed. The authors did not propose a more effective mixing of phases than static mixers, which significantly reduces the solubility of air in water, which is directly transmitted in the amount of air bubbles formed.

R. Etchepare, H. Oliveira, M. Nicking et al. in a published book entitled "Nanobubbles: Generation by Multiphase Pump, Properties and Features in Flotation" describe a micro-nanobubble generation system that is later used in the flotation process, in order to improve the efficiency of sludge separation in the flotation chamber from wastewater to remove suspended matter. For this, a system equipped with a multiphase pump is used. The proposed solution differs from the solution presented in the book in that it is used to dissolve the gas in the liquid, i.e. it aims to dissolve the gas completely without the formation of bubbles that indicate undissolved gas, while the procedure in the book foresees the production of fine gas bubbles, whose role is raise the solid particles up to the level of the wastewater surface in order to further remove them mechanically.

Kim Yu Beom in application no. KR101771124 DEVICE FOR DISSOLVING OXYGEN AND PROCESSING THE SAME describes a water aeration system using spray nozzles that reduce the size of liquid droplets passing through a gas atmosphere. The solution according to the invention carries out the process under high pressure and maintains the condensed water mixed with gas molecules under overpressure until the gas is completely dissolved in the liquid.

Agronomist R.J. and Pisklov G.A. in application RU 94030202 PROCEDURE FOR SATURATION OF LIQUID WITH GAS describe the procedure for saturating the liquid intended for the flotation process with gas. In their solution, they use a thermo-compressor to reduce energy consumption. In the invention according to the application, a conventional pump is used, and the increase in dissolved oxygen is based on an extended residence time.

Widley P.S. in the application WO2013017935 DEVICE AND PROCEDURE FOR LIQUID SATURATION WITH GAS describes the process of aeration of liquids using a device for passing accelerated flows of liquids in a gas atmosphere. The solution according to the invention uses the free fall of liquid particles at significant overpressure and extended retention time at a certain flow rate.

Sulejman's B.A.O in the application EA030820 PROCEDURE FOR THE PRODUCTION OF NANO-FLUID WITH NANO-BUBBLES OF GAS describes the process of producing a gas-saturated liquid by carrying out the process under pressure. In the solution according to the invention, the liquid is saturated with micro-nano bubbles to increase its contact surface with oxygen, and is then held in a flow tank so that the oxygen is completely dissolved before the liquid expands.

Lugovkin A. N. and Kuznetsov A. D. in the application RU2236898 DEVICE FOR LIQUID SATURATION WITH GAS describe a device for improving the efficiency of liquid saturation with gas based on increasing the efficiency of the liquid dispersion process in the chamber. In the solution according to the invention, the increase in efficiency is based on the combination of saturation with micro-nano bubbles and prolonging the hypertensive retention time while maintaining the appropriate flow rate.

Ignatkin V.I. in application RU2230700 METHOD AND DEVICE FOR LIQUID SATURATION WITH GAS AND LIQUID DOSING presents a method for improving the efficiency of gas dissolution in a liquid using a device that uses a heat exchanger to improve solubility. In the solution according to the invention, all processes take place at a constant temperature.

Agronomist R.V. and Piskolev G.A. in application EP0700873 (A1) WASTEWATER TREATMENT PROCEDURE, SUSPENDED MATTER SEPARATION PROCEDURE AND LIQUID SATURATION PROCEDURE WITH GAS describe a wastewater treatment process based on saturating wastewater with gas under pressure, and then, before dissolving the gas in the liquid, expanding it to created air bubbles so that the contaminants float. In the solution according to the invention, the goal is to fully and completely dissolve the gas in the liquid, which will ensure the absence of gas bubbles after the expansion of the liquid at atmospheric pressure.

In the state of the art, chambers with activated sludge are aerated by means of membrane discs or tube diffusers, and by means of surface aerators. Aeration using diffusers placed at the bottom of the chamber consists of introducing atmospheric air into them by means of a blower. In this process, air bubbles with a diameter of 1-2 mm are formed on the surface of the membranes, which rise to the surface of the wastewater. The aeration process using surface aerators is based on the movement of the aerator blades that suck waste water from the bottom of the tank towards the aerator into whose body the waste water is ejected when the direction of the waste water suddenly changes from axial to radial. During this process, the wastewater is intensively mixed using atmospheric air for aeration. The oxygen transmission coefficient of membrane diffusers oscillates at the level of 8% per meter of mud chamber depth, and depends on the manufacturer, and a total value exceeding about 70% for the entire chamber cannot be achieved. This translates into a standard areation efficiency in the range of 3-8 kgO2/kWh. For surface aerators, the standard aeration efficiency does not exceed 3 kgO2/kWh. The areation procedures presented here, due to their low energy efficiency, contribute to the creation of about 60% of the operating costs of the entire treatment plant.

Contrary to the known state of the art, in the solution according to the invention, due to the introduction of compressed oxygen into the gas dissolution chamber, where there is water mist under pressure previously saturated with micro-nano bubbles, which has a developed surface thanks to the sprayers used, it is possible to achieve a high concentration in the aerated water oxygen >30 g/m3. Thus, an oxygen transfer coefficient of >99% can be obtained, which will consequently enable the achievement of a standard aeration efficiency of 10-12 kgO2/kWh. Compared to high-efficiency air diffusers, this will lead to, on average, a 15-fold reduction in the volume of media injected into activated sludge chambers, significantly increasing the oxygen transfer coefficient depending on the exchange surface, pressure and temperature while maintaining the same oxygen concentration in the chamber, which will directly affect the application of much smaller blowers. The formation of nanobubbles is also of critical importance in conducting flotation, where any reduction in the size of the flotation particles results in an increase in the efficiency of the process and thus in a reduction in the volume of the flotation device.

The purpose of the invention is to obtain, in an energy-efficient manner, water with a high (>30 g/m3) oxygen concentration for the purposes of the purification process.

The essence of the invention is a system for saturating a liquid with gas, which consists of a liquid source, a gas source, a gas dissolution chamber and a container for receiving liquid, wherein the liquid source is connected via a pipeline equipped with a pump to the cavitation system, which is connected via a pipeline with gas dissolution chamber, where the end of the pipeline is a set of atomizing nozzles located in the gas dissolution chamber to which the gas source is connected via a gas line to the nozzle. The gas dissolution chamber is connected via a pipeline with a regulating valve to a holding chamber with alternately arranged, partially open partitions, which is connected via a pipeline with a valve to a container for receiving saturated liquid.

Preferably, the set of spray nozzles is equipped with static inserts, which are preferably made of stainless material, the edges of which are bent inward at an angle of 20 to 40 degrees with respect to the surface of the insert.

The essence of the invention is the process of saturating liquids with gas using the system described above, where the liquid from the liquid source is pumped using a pump, raising the liquid pressure to at least 4 bar absolute pressure, through the pipeline, into the cavitation system, whereby the liquid is saturated with gas in the form of micro-nano bubbles, then it is pumped through the pipeline to a set of atomizing nozzles by means of which the liquid is dispersed in the gas dissolution chamber, the liquid being additionally saturated with gas coming from the gas source through the gas pipeline and the nozzle, where the supplied gas has a pressure equal to the pressure of the liquid, and then, through the pipeline, the liquid is pumped into the holding chamber through which it flows in a time not shorter than 13 minutes and at a linear speed not exceeding 0.5 m/s necessary to dissolve the gas, after which the liquid is pumped through the pipeline into the tank for receiving the liquid.

According to Henry's law, the number of moles of a certain gas that can be dissolved in a certain liquid depends on the pressure and the constant that characterizes the given gas and liquid, which depends on the temperature at which the liquid is saturated. Therefore, it is undoubtedly clear that any increase in pressure in the liquid saturation process will lead to an increase in gas solubility. It was decided that the saturation process is carried out under a pressure of 4 bar(s), because it is economically justified - it is a compromise between energy consumption and the obtained concentrations of dissolved gases. The application of the highest level of liquid atomization is beneficial due to the increase in the contact surface of the gas and liquid phases, which results in an increase in the efficiency of the process.

Using a retention chamber in the presented solution with a retention time of at least 10 minutes and obtaining the resulting contact surface of the gas and liquid phases ensures adequate mixing and access of oxygen to the entire volume of aerated liquid. For a mixture pressure of 4 bar absolute pressure and a flow rate in the range of 0.4 - 0.6 m/s, the minimum retention time is 10 minutes - so the shape of the retention chamber should provide a volume sufficient to store the mixture, in the same amount that flows through the system in 600 seconds. The absolute pressure of 4 bar is the minimum value, however, it is possible to carry out the oxygenation process at a higher pressure and for every bar of absolute pressure increase, the required retention time is reduced by 15%, but the process pressure must not exceed 6 bar of absolute pressure due to the restrictions refer to devices for separating oxygen from air whose maximum pressure after separation is 6 bar absolute pressure.

The invention is shown in drawings, in which figure 1. shows a preferred variant of the system for saturating the liquid with gas, and Fig. 2 represents a preferred variant of the nozzle assembly.

Implementation example 1

The system consists of a gas dissolution chamber (1) made of stainless steel 316L, external diameter 500 mm, height 2000 mm and wall thickness 3 mm, waste water collection tank (3), centrifugal pump (8) adapted for pumping liquids with with a maximum diameter of solid particles of 1 mm and a liquid pressure of up to 4 bar(s), a pipeline (11) made of polyethylene, an expensive spray nozzle (7) with a droplet diameter of atomized liquid not exceeding 5 microns, made of PVDF plastic and equipped with static inserts made of stainless steel 316L with a thickness of 1 mm. The nozzles (7) are connected by a polyethylene pipeline (16) to the cavitation system (14) whose injector is made of stainless steel 316L, which sucks atmospheric air in the amount of 3 Nm3/h, forming air bubbles with a diameter of 100 nanometers. The gas dissolution chamber (1) is connected to a gas source (5) in the form of an oxygen cylinder of purity above 95%, through a gas line (10) made of stainless steel 316L and a nozzle (6) made of stainless steel 316L. The gas dissolution chamber (1) is connected to the retention chamber (2) made of 316L steel, 2200 mm diameter, through a pipe (12) of 80 mm diameter 316L stainless steel and a knife type control valve (9) of 316L stainless steel. , height 1200 mm and wall thickness 3 mm, in which semicircular (17) partitions are placed; which is connected via a pipeline (13) made of stainless steel 316L with a diameter of 80 mm to the collection point of oxygen-saturated waste water (4).

Implementation example 2

The process of saturating liquids with gas, whereby the liquid, from the liquid source (3) which is a buffer for municipal waste water with a suspension content of 240mg/l and BZT5 at the level of 250mg/l in an amount of 20m3/h at a temperature of about 25 degrees Celsius, is pumped by means of a centrifugal circulation pump, adapted for pumping liquids classified as municipal wastewater (8), raising the pressure of the liquid to at least 4 bar(s), through a pipeline (11) made of polyethylene, into a cavitation system (14) where the liquid is saturated with gas (atmospheric air) with a bubble diameter between 50 and 100 microns, and is then pumped through a pipeline (16) made of polyethylene to a set of spray nozzles (7) to a droplet diameter of no more than 5 microns, made of PVDF plastic, equipped with static inserts made of stainless steel 316L with a thickness of 1 mm, whose task is to break the accumulated suspended solid particles into smaller fractions, in order to protect the nozzles from clogging. This is achieved by using turbulent flow and accompanying forces by which the liquid is dispersed in a gas dissolution chamber (1) made of 3 mm thick 316L stainless steel, 2200 mm in diameter and 2000 mm high, where the liquid is additionally saturated with gas (oxygen with a concentration of 95%) originating from a gas source (5) in the form of an oxygen generator (PSA - Pressure Swing Adsorption Type) which is supplied through a gas pipe (10) made of stainless steel 316L and a nozzle (6), whereby the supplied gas has a pressure equal to liquid pressure.

As a result of the atomization of the liquid into droplets with a diameter of 5 microns and their injection into the gas volume under pressure in the gas dissolution chamber (1), the liquid-gas exchange surface expands to a value of 1200 m2, which is 1000% more than in the conventional solution, while the maintained pressure of 4 bar(a) increases the gas dissolution coefficient in the liquid, and is 5 times higher than the observed coefficient in the case of surface aeration, which enables a very dynamic and efficient gas saturation process. Then, through a pipeline (12) made of 316L stainless steel, the liquid is pumped into a retention chamber (2), made of 316L steel, with a diameter of 2200mm, a height of 1200mm and a wall thickness of 3mm, in which semicircular baffles (17) are placed, alternately welded to the intended retention time in the chamber was achieved and prevented the incorrect retention time that would have occurred if the retention chamber was completely pass-through (no baffles). The baffles (17) are made of stainless steel 316L, 5 mm thick, and ensure a retention time in the retention chamber (2) of no less than 13 minutes and a linear velocity of no more than 0.5 m/s required for gas dissolution. Then, through the pipeline (13) made of stainless steel 316L, the liquid is pumped into the tank for receiving the liquid (4), which is the next stage of the system for biological treatment of waste water, i.e. flotation. With the implementation of this invention, its purpose has been achieved. After applying the procedure described above, a liquid with a very high oxygen concentration exceeding 30 g/m3 was obtained.

Claims (3)

1. A system for saturating a liquid with oxygen, which consists of a liquid source (3), an oxygen source (5), a gas dissolution chamber (1) and a container for receiving a saturated liquid (4), indicated by the fact that the liquid source (3) waste water collection tank and is connected by a pipeline (11) which is equipped with a pump (8) with a cavitation system (14) which is connected via a pipeline (16) to a gas dissolution chamber (1), where the end of the pipeline (16) is a set spray nozzles (7) located in the gas dissolution chamber (1) to which the oxygen source (5) is connected via a gas line (10) to the nozzle (6); and the gas dissolution chamber (1) is connected via a pipeline (12) with a control valve (9) to a retention chamber (2) with alternately arranged, partially open partitions (17), which is connected via a pipeline (13) with a valve (15) ) connected to the container for receiving the saturated liquid (4). 2. A system for saturating liquid with oxygen according to claim 1, characterized in that the set of spray nozzles (7) is equipped with static inserts (7a), which are made of stainless material, and whose edges are bent inward at an angle of 20 to 40 degrees in relation to the surface of the insert. 3. The process of saturating the liquid with oxygen using the system according to claim 1, characterized in that the liquid is pumped from the liquid source (3) using the pump (8), raising the liquid pressure to at least 4 bar, through the pipeline (11), into the cavitation system (14). where the liquid is saturated with gas in the form of micro-nano bubbles with a diameter of 100 nanometers, and then it is pumped through the pipeline (10) into a set of atomizing nozzles (7) by which it is sprayed into the gas dissolution chamber (1), where the liquid is additionally saturated with oxygen which comes from an oxygen source (5) which is supplied through a gas pipe (10) and a nozzle (6), whereby the supplied oxygen has a pressure equal to the pressure of the liquid, and then through the pipe (12) the liquid is pumped into the retention chamber (2) through which flows for no less than 10 minutes at a linear speed of no more than 0.5 m/s, which is necessary to dissolve the gas, and then the liquid is pumped through the pipeline (13) into the tank for receiving the saturated liquid (4).