RU1824438C - Method of aeration of culture liquid of microorganisms - Google Patents

Abstract

Usage: microbiological industry, the cultivation of microorganisms in a liquid medium during aeration. The inventive method involves the continuous supply of gas under a layer of culture fluid in the fermenter and the discharge of exhaust gas, while the fermenter tank is sealed and created in it by pumping the exhaust gas with a vacuum pump, and the degree of vacuum is maintained within the limits corresponding to the boiling point of the culture fluid in the optimal cultivation interval of microorganisms 32 - 38 ° C, technical oxygen being supplied as aeration gas, 1 sludge.

Description

The invention relates to the microbiological industry, in particular, to aeration methods in the cultivation of microorganisms utilizing methanol, ethanol, n-paraffins, hydrolysates, sulphite liquor, agricultural waste, etc.

The purpose of the invention is to reduce energy consumption and increase utilization; providing a gaseous substrate.

This is achieved by the fact that the method of aeration during the cultivation of microorganisms, involving continuous aeration of the liquid phase with the components of the substrate distributed in it, is carried out under vacuum, sealing the container with the appropriate boiling point of the liquid phase equal to the optimal cultivation temperature. In this case, the boiling point of water decreases. Aerating gas. entering the fluid layer

through a dispersing device, it initiates the formation of steam caverns. In a boiling manner, the vapor bubbles collide, crush, and mix in a layer of liquid. The surface layer of the vapor-gas interface is actively turbulized due to water molecules evaporating from this surface. With a stable boiling mode, the rate of evaporation of the liquid phase is several orders of magnitude higher than the required rate of dissolution of the aerating gas in the liquid and the process, aeration will be limited by the supply of heat required for evaporation. Obviously, in this case, the mass transfer rate will be determined by the rate of supply of fresh gas to the phase boundary, i.e. the amount of gas supplied to aeration.

During the cultivation of microorganisms, the limitation of the process will be in the transition region of the liquid-cage boundary (L

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k, and is determined by the rate of biosynthesis, but in any case, the oxygen transfer rate will be higher than in traditional aeration methods, since energy is introduced and the apparatus from the outside (mixers, pumps, ejectors, etc.) is mainly spent on creating a contact surface phases, and to overcome the resistance of the surface layer of the liquid phase at the gas-liquid interface. In the proposed method, this energy is supplied from the inside by the heat generated by the biochemical reaction.

The process of oxygen mass transfer passes from the diffusion region (in which the main resistance is concentrated from the gas-liquid interface) to the kinetic one and the rate of heat input resulting from the biochemical reaction is determined, thus the process becomes self-similar. All the heat that is optimal for the fermentation process goes to the evaporation of water. At the same time, the phase separation surface is constantly updated and the mass transfer of the aerating gas, the main component of the nutrition of microorganisms, is accelerated. When cultivating microorganisms, the overall fermentation rate will be determined by the kinematic characteristics of the microorganism culture strains,

The drawing schematically shows a diagram of the proposed method of aeration during the cultivation of microorganisms.

The fermenter is a container 1 with an oxygen distributor 2 installed in it, oxygen supply nozzles 3, an outlet 4 for exhausting the vapor-gas mixture and 5 for selecting the yeast suspension, and an integrated droplet separator 0. The exhaust gas mixture is sucked off by the vacuum pump 7 and enters a factory purification system or recirculation to collect the remaining oxygen and return it to aeration.

The advantage of the proposed aeration method is the self-similarity of the process of growing microorganisms. The more heat will be generated during fermentation, the more intensive the evaporation process and, accordingly, the mass transfer rate of oxygen. In the apparatus implementing the proposed method, the need to use heat exchangers, mixing devices, diffusers, and generally any internal devices with the exception of aerators will disappear.

Example 1. In an apparatus with a working volume of 1 m, yeast assimilating i-zlkans is cultivated.

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The main gaseous component of the feed is oxygen (it is disadvantageous to supply air, since the resulting carbon dioxide is blown off by steam generated during boiling).

Mineral salt solutions, water, substrate, sowing yeast are supplied to the apparatus, the supply of technical oxygen is turned on, and the gas-vapor mixture is pumped out with a vacuum pump.

The cultivation process is carried out at ... 34 ° C.

An absolute pressure value of 0.05 kgf / cm must be achieved for the water to boil. The specific growth rate of microorganisms is 3 kg / m3-hour. This produces 180 kcal of heat.

At a specific heat of vaporization of about 600 kcal / kg, about 30 kg of water will evaporate, resulting in 750 m3 / hour of steam. The required amount of oxygen will be 6 kg 02 / hour or 8.5 m3 02 / hour.

Taking into account that the degree of use in the best apparatuses today rarely exceeds 25 ... 30%. We take an oxygen consumption of 30 m / h. A little more than 4 kg of carbon dioxide, or 8 kg of CO2 / hour, is released.

The total amount of steam withdrawn necessary to maintain optimum. boiling temperature (up to 35 ° С) will be 800 m3 / h. The specific energy consumption is about 4.0 kW / m3. Studies have found that when culturing yeast 5 on n-alkanes with a specific mixing power of 4.0 kW / m3, the degree of oxygen utilization is,%:

for apparatuses with mechanical stirring 20% 0; for apparatuses of column type 15%.

For the proposed method, the degree of utilization of oxygen will be 25 ... 28%.

Example 2. In the apparatus, with a working volume of 10.0 m, 5 yeast hydrolysis is cultivated.

The oxygen demand, with a specific productivity of 1.5 kg / m3 / h, will be 10.0 m3. The required consumption of technical oxygen is about 40.0 m3 / hour. 0 In this case, 8.0 m3 / hZs of carbon dioxide will be released. A pillow is created in the apparatus from solutions of salts and trace elements, water, seed yeast is poured, the flow of aerating gas-oxygen is turned off. 5 When the biomass concentration reaches a certain technological regulation, two vacuum units with a total capacity of 1100 m3 / h are included.

Installed power - 19 kW. The amount of gas-vapor mixture taken from

apparatus to maintain the boiling mode (37 ... 38 ° C, P - 0.05 kgf / cm7) is defined as the sum of the evaporated water and aerating gas and is 11250, О m3 / h, while the total amount of gas-vapor mixture will amount to 11.5 thousand m / h; specific stirring power 2 kW / m3; degree of utilization of oxygen not less than 20 ... 25%. whereas in existing fermentation systems no more than 5 ... 10%.

The driving force for the mass transfer of oxygen in this process is proportional to its partial pressure in the gas phase and, in general, will be lower compared to aeration under normal conditions. From the main mass transfer equation it follows that in the proposed method, when the driving force of oxygen is reduced in proportion to the decrease in the partial pressure of oxygen, the volumetric mass transfer coefficient will increase, firstly, due to a significant increase in the phase contact surface, since along with ordinary aeration will

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sharpened the main resistance to mass transfer (80-90) of the total mass transfer time). Consequently, the oxygen sorption rate will remain unchanged while maintaining a constant specific mixing power.

At the same time, the degree of oxygen utilization will increase by a factor of 2 or more, which will reduce the specific energy consumption for aeration.

Claims (1)

SUMMARY OF THE INVENTION A method for aerating a culture liquid of microorganisms, which provides for continuous supply of gas under a liquid layer into a fermenter vessel and subsequent exhaust gas discharge, characterized in that, in order to reduce energy consumption and increase the utilization rate of the gaseous substrate, the fermenter vessel is sealed and creates a vacuum therein by pumping the exhaust gas by a vacuum pump, while the degree of vacuum is maintained in the preVl / Ow I 14 Aiy × W / Of t Jr I rj ..-..-- (.- p-. “., there is a voluminous boiling of liquid liquids corresponding to the temperature of the vapor. and secondly, by reducing the resistance to oxygen diffusion through the gas-liquid boundary layer. When boiling liquid, it is in this layer that concentrates 6L I BY no culture fluid in the optimal range of microorganism cultivation of 32-38 ° C, and technical oxygen is supplied as the aeration gas. 0 5 0 sharpened the main resistance to mass transfer (80-90) of the total mass transfer time). Consequently, the oxygen sorption rate will remain unchanged while maintaining a constant specific mixing power. At the same time, the degree of oxygen utilization will increase by a factor of 2 or more, which will reduce the specific energy consumption for aeration. SUMMARY OF THE INVENTION A method for aerating a culture liquid of microorganisms, which provides for continuous supply of gas under a liquid layer into a fermenter vessel and subsequent exhaust gas discharge, characterized in that, in order to reduce energy consumption and increase the utilization rate of the gaseous substrate, the fermenter vessel is sealed and creates a vacuum therein by pumping exhaust gas by a vacuum pump, while the degree of vacuum is maintained in ..-..-- (.- p-. "., 5 cases corresponding to the temperature of the kipedels, corresponding to the temperature of the bale no culture fluid in the optimal range of microorganism cultivation of 32-38 ° C, and technical oxygen is supplied as the aeration gas. Oshrayomamye gaz / NO ovucsnxy about the recirculation node