FR2506327A1 - Slowing and opt. halting gas generation from fermentation - by increasing gas pressure e.g. in digester or cider bottle - Google Patents

Abstract

The fermentation takes place inside a pressure vessel in which the fermenting material is subjected to pressure by a gas. The pressuring gas is composed at least in part of gas of the type produced by the fermentation. The rate of fermentation varies inversely as the pressure of gas within the vessel, i.e. an increased gas pressure results in a reduced rate of fermentation and vice verse. Gas generated by the fermentation process is pref. employed as the pressurising gas. Control of gas pressure can then be effected by regulating the rate at which gas is drawn off from the vessel. The pressure vessel is pref. constructed to withstand an internal pressure high enough to halt the fermentation process. The method can be used by filling cider into very strong bottles so that in-bottle fermentation will be arrested when gas pressure rises to a critical level. The rate of biogas generation in a digester can be controlled by regulating gas take-off. The ferments are reactivated when pressure is reduced by opening the bottle.

Description

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The present invention relates to the control of farms producing gas.

 By control, we e @ tend here the action of accelerating or slowing down by volo @ t the progress of the fermentation.

 A number of existing processes for implementing fermentation phenomena do not seek to control the progress thereof, but to reach a certain final state in the general reillers.

Other procedures aim to prevent the continuation of fermentation (conservation), the means used are essentially temperature control (low for conservation, temperate and constant in other cases) and / or action on the chemical composition of the medium.

 In known techniques concerning fermentations producing Uaz, the ingredients of the reaction are retained in an enclosure which, generally, continuously lets out the gas produced.

 in some cases, on the other hand, the enclosure is sealed, but only when the fermentation has reached a stage such that the quantity of gas remaining to be produced is low (example of unpasteurized cider cider).

 The present invention retains from these latter cases the fact that fermentations can occur under pressure greater than the atmospheric.

 So we know that putrefaction, a category of fermentation producing carbon dioxide, can occur in abyssal depths where the total pressure can reach several hundred times the atmospheric. still it is necessary, in this case, to distinguish from the total pressure the partile pressure of the chemical species produced, carbon dioxide: this partial pressure is little different from that which prevails in the vicinity of the surface.

 The invention is based on the fact that an increase in the partial pressure of the gas produced slows down the fermentation while a decrease in this pressure accelerates it, all other things being equal. @more precisely, the invention relates to a process characterized by the fact that a pressure agent is used to control the kinetics of the fermentation producing gas as required, the pressure field thus created allowing it alone to accelerate or to slow down the reaction at will, the said agent containing at least the same chemical spaces as the gas generated by the fermentation.

The method of the invention can have, in addition, at least one of the following characteristics
- the pressure agent contains quantities of gas produced by fermentation
- The variations in the pressure field are obtained by acting on the evacuation of the gases produced.

 The invention also relates to a device for implementing the process, characterized in that the enclosure which for a time contains the materials involved in the fermentation is constructed to withstand a pressure such that, once this pressure is reached, the fermentation either do this fact significantly slowed down. As a variant, the enclosure is provided with a variable means for evacuating the gases making it possible to vary the pressure in Itonceinte, within the required limits.

 Returning to the example of cider cork, we know that we must seal the bottle when the concentration of fermentable sugars is lowered to a precise level: too late, the remaining quantity will be too low and the carbon dioxide produced in quantity insufficient, will not sparkle cider; too early, too abundant production confined in a relatively fragile bottle will burst it. On the other hand, according to the invention, if the bottle were sufficiently resistant, the carbon dioxide pressure would rise there to the point of stopping the fermentation before the complete consumption of the sugars. This last result is sometimes sought, but it is obtained by other methods such as pasteurization.

 This latter process, however, is almost irreversible as it destroys the active stages of fermentation. This is not the case with the present invention, where the active agents are only inhibited by the increase in the partial pressure of the gas which they produce, and regain their activity when this pressure is lowered.

 The invention is particularly useful in the case of fermentations in which the most sought-after product is gas, such as, for example, methane fermentation producing "@iogas". In these cases, the rate of consumption of gas no generally does not coincide with that of its production, this key, with the currently known chemicals, causes losses or complex storage problems. It would be preferable to store the ingredients of the fermentation and act on its kinetics to adapt the production of gas to needs. is what the invention allows to achieve.

 The simplest case is that where consumption requires only a pressure slightly higher than the atmospheric one as for example the domestic uses of combustible gases, while the kinetics of methane fermentations remain appreciable at higher pressures. The complete installation, including the invention in one of its variants, is then limited to a tank resistant to internal pressure (between 10 and 30 times atmospheric pressure for example) equipped with a pressure regulator regulating the flow according to the requirements (type regulator gas cylinder ligated fi6), a safety valve, an introduction and draining system for liquids and solids involved in the reaction and possibly simple heating. In this case, instant consumption can vary from zero to several times ## average production without delay and without loss.

 The practical data for manufacturing and installing the device of the invention (shapes, dimensions and design pressure of the enclosure, practical design of the pressure control system) depend on the circumstances of use and are not included in the claims.

Claims (5)

 1. Process for acting on a generating fermentation gas, characterized by the fact that a pressure agent is used to control the kinetics of the reaction as required, the field of prediction thus created @ allowing alone to slow down or accelerate at will the evolution of the process chemical, the so-called pressure agent containing at least the same chemical spaces as the az generated by fermentation  2. vroeedé according to claim 1 characterized in that the pressure agont consists essentially of (the quantities of gas produced by the fermentation itself.  3. Method according to at least one of claims 1 and 2, charac- terized in that the variations in the recession cap are obtained essentially by acting on the evacuation of the quantities of gas produced.  4. Device for implementing the method according to one of the preceding claims, characterized in that the enclosure which for a time contains the materials involved in the fermentation is constructed to withstand a pressure such that this pressure once reached according to at least one of the said claims, the fermentation alone is significantly slowed down.  5. @ device according to claim 4 characterized in that the enclosure is provided with a variable means of gas evacuation, making it possible to control the pressure in the enclosure within the required limits.