BRPI0721329A2 - BIOGAS EXTRACTION PROCESS AND CORRESPONDING DEVICE - Google Patents

Description

BIOGAS EXTRACTION PROCESS AND CORRESPONDENT DEVICE The present invention relates to the field of biogas extraction.

More precisely, the invention relates, according to a first of its aspects, to a biogas extraction control process of a compartment (50) equipped with at least one extraction set (31A, 31B), each extraction set being connected to a respective manifold (70A, 70B) by means of a respective control valve (10A, 10B) and comprising at least one unitary extraction device (311A, 312A, 313A, 31B), the process comprising the steps comprising: consist of:

providing a predetermined manifold pressure (Pr) corresponding to each manifold (70A, 70B); and

open the control valve (10A, 10B) in a certain position.

Biogas extraction depends on internal parameters (type of waste, bacteria, amount of air / oxide, age of waste), and parameters external to the compartment. The distribution of production zones in the middle of a compartment is heterogeneous.

The prior art document US 6169962 is known to the technician.

Biogas extraction is controlled well by well. The proposed system comprises a trap measuring device at each wellhead for measuring the flow rate, vacuum, temperature, and 02 / CH4 / CO2 content of the extracted gas. The measurement information is sent to a remote computer which, in return, by reference to a model, controls the respective opening / closing of a pneumatic control valve of each well, the pneumatic control valve, allowing to adjust the flow of extracted gas. well by well.

However, such a system does not allow consideration of network disturbances or extraction disturbances due to atmospheric disturbances.

The prior art document EP 1291093 is also known in the art. The biogas extraction process proposed by this patent is based on a measure of relative pressure between atmospheric pressure and gas pressure in waste.

Gas extraction is based on a convention, depending on weather forecasts, so that the password is lowered earlier when weather forecasts predict a drop in atmospheric pressure.

However, this solution does not allow optimal capture, as it depends on a weather forecast, which itself has a higher or lower level of uncertainty in value, time and space.

The present invention aims to prevent the drawbacks by proposing a solution to capture biogas optimally, that is, the captured flow is equal to the flow produced by the waste.

For this purpose, the device according to the invention, on the other hand, according to the above preamble, is essentially characterized by the fact that it further comprises the steps consisting of:

- measure the value of a weather parameter external to the compartment;

calculate a global pressure differential password (dPci) as a function of the value of the measured meteorological parameter;

- measure the relative pressure (dPi) at the level of at least one extraction set;

- compare the relative pressure measured to the password value (dPci); and

change the position of the control valve (10A, 10B) as a result of the comparison result.

In one embodiment, the process further comprises the steps consisting of:

provide a first local password (dPcil) by comparing the value of the measured weather parameter (s) to a reference model;

- the step of calculating the global password (dPci) being a function of this first local password (dPcil).

Thanks to this feature, the effects of weather conditions on the amount of biogas to be captured can be anticipated.

Preferably, the measured external meteorological parameter is comprised of the set comprising atmospheric pressure, external temperature and rainfall.

In one embodiment, the process comprises the steps consisting of:

- measuring the value of a physically-regulated internal parameter within the set (02 / CH4 / CO2 content, pressure temperature) at the level of at least one extraction set;

- compare the measured value to a reference value; and

- provide a second local password (dPci2) according to the comparison; - the global password (dPci) calculation step being a function of this second local password (dPci2).

Preferably, the reference model is constructed by a prior learning step, in which the evolution of the internal pressure in the manure mass is measured as a function of the value of the external and / or internal parameter (s) ( s measured.

Thanks to the invention, one can cite the variations linked to the operating conditions on a biogas extraction network.

The relative pressure obtained at the extraction system level is dependent on the relative pressure value imposed at the collector level by the biogas aspiration systems. In all cases, the pressures (dPi, Pr, Pi) are differential pressure values relative to atmospheric pressure.

For this reason, the notions of relative pressure and differential pressure will be used interchangeably.

The invention also relates, according to another aspect, to a biogas extraction control device, capable of applying the process according to the invention, the device comprising:

- a housing (50) equipped with at least one extraction assembly (31A, 31B), each extraction assembly being connected to a respective manifold (70A, 70B) via a respective control valve (10A, 10B). and comprising at least one extraction unit (311A, 312A, 313A, 31B);

means for providing a manifold pressure (Pr) to the respective manifold (s) (70A, 70B); and means for opening the control valve (10A, 10B) in a given position.

The device is essentially characterized by the fact that it further comprises:

means for measuring the value of a weather parameter external to the compartment;

means for calculating a global pressure differential password (dPci) as a function of the measured meteorological parameter value;

means for measuring differential pressure (dPi) at the level of at least one extraction set;

means for comparing the relative pressure measured to the password value (dPci); and

- means for changing the position of the control valve (10A, 10B) as a function of the comparison result.

In one embodiment, the device further comprises:

- means for providing a first local password (dPcil) by comparing the value of the measured meteorological parameter (s) to a reference model, the global password (dPci) calculation step being a function of that first local password (dPcil).

Preferably the device according to claim further comprises learning means configured to measure the evolution of internal pressure (Pi) as a function of the value of the external meteorological parameter (s). (s) measured, the reference model being constructed from the means of learning. In one embodiment, the device further comprises:

means for measuring the value of an internal physicochemical parameter comprised in the set (02 / CH4 / CO2 content) at the level of at least one extraction set;

means for comparing the measured value and a reference value; and

- means for providing a second local password (dPci2), depending on the result of the comparison, the global password being a function of that second local password (dPci2).

Thanks to the invention, external (meteorological) disturbances can be considered. However, these external disturbances play a larger role in diffuse emissions, some% biogas can be extracted, moreover, in relation to the prior art.

Similarly, thanks to the invention, internal disturbances can be compensated.

The invention therefore allows to dampen biogas production variations due to external parameters, such as internal parameters due to the exploitation of a plurality of networked compartments.

Thanks to the invention, a certain biogas quality can be extracted, that is, a biogas that has a determined methane content in a given range allows to ensure optimum recovery of the extracted biogas, in particular because the recovery systems do not accept significant variations. methane content.

The invention allows to minimize the quality variations of biogas linked to atmospheric phenomena. In fact, when measuring and controlling only the percentage of methane in a well, the resultant of the disturbances of depression is evaluated only a few hours later.

Thanks to the invention, the depression can be adjusted to the level of each well, so that it can be adapted over time, depending on the quality of methane and atmospheric variations, that is, the variation of depression applied, thanks to the model (dPcil) allows to generate the unbalance associated with the change in atmospheric pressure, the biogas quality variations there are smaller.

Other features and advantages of the present invention will appear more clearly from reading the following description given by way of illustration and not limitation, and made with reference to the accompanying figures, in which:

Figure 1 is a representation of an embodiment of the device according to the invention; and

Figure 2 is a synoptic representation of an embodiment of the process according to the invention.

Referring to Figure 1, the device according to the invention comprises a housing 50 equipped with a first set 3IA of first extraction unit devices, in the wells type 311A, 312A, 313A, connected to a manifold 70A by via an IOA control valve. Further, the device may comprise at least a second example 3IB of second extraction unit devices, in-kind a second well 3IlB connected to an intermediate dust collector 70B of an IOB control valve.

Each assembly may therefore comprise a plurality of unitary extraction devices and the device may comprise a plurality of network mounted assemblies as described below.

Each extraction unit, hereinafter referred to as the well, comprises a suction head 41A, 4A, 43A, 4IB for biogas collection in the middle of compartment 50, and each assembly comprises a wellhead, respectively 2OA and 20B.

Control valve 10A, IOB is mounted between wellheads 20A, 20B respectively and primary manifolds 70A, 70B.

Collectors 70A, 70B are connected to a main collector 70 by an appropriate pipeline network, so that in other embodiments, collectors 70A, 7OB and 70 may be the same.

The device comprises means, not shown, such as a constant or variable flow pump, for supplying a manifold pressure Pr, in the negative species, i.e. a dPci depression, to the collector (s) 70A, 70B. The device also comprises means 60, 10 for automatically selectively opening the control valve 10A, 10B respectively in a determined position. Preferably, such means comprise control means 60, in particular a computer or an automaton. The control means can directly control the control valve 10A, 10B. They comprise, or are coupled to regulating means 10. Preferably, the regulating means comprises a first and a second regulator, they are configured to calculate and issue pressure passwords resulting in a change of IOA control valve position, IOB according to different parameters as described later.

Communication between the control means 60 and the control valve 10A, 10B may be by any known means, wired or wireless, the control means 60 may therefore be arranged at a distance.

The device according to the invention also comprises meteorological means 90 for measuring the value of at least one meteorological parameter external to the atmospheric compartment, a temperature thermometer, and a rainfall gauge are arranged on the surface, preferably nearby. 50. These meteorological means 90 communicate with the control means 60.

The control means 60 advantageously comprises prediction means, in the species a reference model in the form of soft, to say the evolution of the internal pressure Pi at the level of each extraction set as a function of the value of the parameter (s). measured weather (s).

For this purpose, the value of the measured weather parameter (s) is compared to the reference model in order to provide a first pressure pass, said local, dPcil, by a regulator R "1 of a first regulating circuit.

The first regulating circuit is said to be slow because it considers changes due to day / night external conditions, stake, and other atmospheric effects.

The first dPcil password achieves a constant quality of the biogas extracted in, as a function of the gas quality password (ie, the methane rate comprised in the biogas fixed by the operator. The methane content represents an example of an internal parameter password in another embodiment it may be gas depression dPi, date, 02 or CO2 content, etc.

Preferably, the reference model is constructed by a prior learning step.

Learning consists, for example, of measuring the evolution of internal pressure Pi as a function of the measured meteorological parameter (s). This evolution can be recorded as a reference model on the control means 60. The model can be pre-established and eventually developed continuously during the exploration of the compartment.

At a given time, the measurement of a given weather parameter is compared to its nearest value in the model. The corresponding internal pressure is then estimated by the previous learning phase.

Thanks to the reference model built with a learning step, a prediction step of the internal pressure evolution Pi can be performed as a function of the measured weather parameter (s) and a local password dPci can be provided. appropriate.

Depending on this prediction of the evolution of internal pressure Pi, the control means 60 then issue a position change password to the control valve 10A, IOB.

Thus, the detection of an external meteorological variation allows to anticipate, to pre-say the biogas production variation, therefore, the internal pressure Pi to a set of wells.

The prediction is linked to the perfect gas law PV = nRT. If the pressure variation is known (measured pressure and temperature), then the volume variation of biogas produced in the compartment will be known (calculated). In addition, an empirical delay factor, identified in situ, plus medium porosity coefficients, etc. allows to determine the pressure variation on both sides of the control valve.

By way of illustration, if the atmospheric pressure is constant and the control valve is open, and the membrane 110 is semipermeable, air will be drawn into the housing and methane will be diluted, which is not desirable.

Thanks to the invention, even if atmospheric pressure varies, the rate of methane extracted from biogas will remain constant.

The device according to the invention advantageously further comprises means for measuring the value of a physicochemical parameter internal to the compartment comprised in the assembly (02 / CH4 / CO2 content, biogas quality, pressure, etc.). at the level of at least one well, in the appropriate catcher species.

Measurements of at least one of the parameters comprised in the set are preferably made sequentially from one extraction head to another and periodically.

The measured content is compared to a reference value, for example, thanks to the control means 60, which issue a second pressure pass dPci2, said local, allowing the position of the control valve 10A, IOB to be changed as a function of the result of the By comparison, the dPci global password is a function of this second dPci2 local password. The second password dPci2 provided by a regulator R '1 of the first regulating circuit.

Advantageously, the regulating means 10 comprise a feedback loop connecting the comparison value and the control valve opening / closing value so as to achieve a precise gradual opening / closing (position), not an opening / a full type closure or not.

In this embodiment, the global password dPci is a function of the two local password passwords dPci and dPci2, in particular the global password dPci is the sum of the local passwords dPcil + dPci2.

The first level of regulation therefore preferably comprises two regulators. Thus, the prediction made at regulator level R "1 is corrected by the measurement made at regulator level R'l. This correction allows at the same time to limit the introduction of air into the compartment, therefore oxygen, in the event of an increase. atmospheric pressure, and limit any methane leakage in case of low atmospheric pressure, so the control valve position password is calculated to always be optimal.

In addition to the evoked atmospheric disturbances, the device according to the invention may also suffer internal disturbances.

In operation, a biogas extraction site is a system comprising a plurality of devices, as described and connected to a main manifold 70, via a pipeline network. The main collet is connected to biogas treatment means 80 (recovery, lamp, etc.).

If, for various reasons, one of the mains pipes is closed, the (constant) depression at the main collector level will be spread over the other pipes. Depression, therefore, pickup flow increases, with the aforementioned risk of air being introduced into the enclosure.

Thanks to the invention, this risk is eliminated by maintaining a fixed flow at each valve level, or more accurately a maximum biogas flow, while maintaining a constant gas quality.

Subjecting the control valve position to differential pressure measurement defines a second regulating circuit, used by a second regulator R2 of the regulating means 10.

This second tuning circuit allows the device to be optimally configured for instant methane production. It is said to be rapid because it allows adaptation to rapid changes in biogas production.

To this end, the device according to the invention comprises means for measuring the differential pressure dPi at the level of at least one extraction set.

The measured relative pressure dPi is compared to a password value dPci and a change of position of the control valve is made, depending on the result of the comparison, by the regulator R1.

This means that, depending on the password dPci, the regulator R1 sends an open / close command signal from the control valve, defining a depression value to be applied at that valve level. Thus, the regulator R1 has as its input parameter at least the differential pressure, and eventually the local temperature, on both sides of the considered valve, these variables being measured. The regulator R1 has as its password a determined differential pressure value dPci. If the measured differential pressure dPci is different from the password value, the valve position will be modified by regulating means 10 to achieve the password differential pressure.

The control means 60 are advantageously used as means for comparing the measured relative pressure to a reference value, and as means for providing via the regulating means 10 a first control valve position change password as a function of the result. of comparison.

Preferably, the dPci password is fixed, predetermined for each extraction head. In addition, this password is advantageously determined as a function of the first setting circuit.

The use of differential pressure as a control variable eliminates the disturbances associated with variations in biogas extraction network depression, such as: operating incident, subpart isolation, changeover of extractors.

Regarding the measured external meteorological parameters:

In one embodiment, the external parameter is external temperature, because temperature influences biological reactions, therefore, biogas production (low activity with a low temperature, for example, in winter). However, the influence of temperature remains less than the influence of the following two parameters (rainfall and pressure).

In one embodiment, the external parameter is rainfall.

There is on the surface of a compartment a so-called layer range zone. These zones have a thickness of the order of magnitude of a few meters, typically 4-5 m. Due to their geological situation, these zones are alternately aerobic and anaerobic due to rainfall, and therefore unusable for methanogenesis, as they are not maintained in strict anaerobic condition.

These upper compartment layers are often clayey (clay or otherwise). In case of rain, the clay acts as a waterproof layer, and the catchment flow can therefore be increased.

In the event of a storm, for example, it is therefore possible to have a rapid increase (under a few hours) of biogas quality.

Thanks to the invention, the thickness of the gap zone is greatly reduced, even almost zero, by controlling biogas extraction.

The invention advantageously anticipates the impact of rainfall on the extraction of biogas, as precipitation causes the clay roof to clog. This favors a decrease in air intakes and allows for increased depression to be supplied to the waste stream to capture more biogas. In addition, a dry spell causes cracks to form on the roof and creates emissive zones. The invention allows to limit the air intakes in the sludge mass, also regulating the oxygen rate present in the biogas.

In one embodiment, the external parameter is atmospheric pressure.

As atmospheric pressure increases, the volume of biogas produced in compartment 50 decreases, and the risk of capturing air increases (PV = constant).

Conversely, when atmospheric pressure decreases, the volume of biogas produced in compartment 50 increases and the risk of biogas leakage into the atmosphere increases.

Also, if the pressure for the Pi uptake is too great. The risk of dilution will increase (introducing atmospheric air into the enclosure) and if the pressure Pi is too low, the risk will be to increase the pressure in the sludge mass, thereby losing biogas in the atmosphere and inhibiting biogas production reactions.

The invention makes it possible to capture biogas optimally so as to avoid both air introduction and methane emanation.

By way of example, the surface area of a room may be of the order of hectare (1 hectare = 10,000 m2). For a compartment volume in the order of one million m3, a 20OPa / h atmospheric pressure range generates a biogas volume change of approximately 200 m3 / h after a certain latency time (transmission / inertia time device).

Regarding oxygen, it inhibits methanogenesis.

In one embodiment, measurement means may be provided in the extraction heads and a password for the oxygen content at the first setting level, so that the extracted oxygen does not exceed a certain amount, therefore, to maintain a certain quality of the product. biogas.

Likewise, it is possible to provide in another embodiment means of measurement in the mass of waste, which translates a possible air intake in the compartment. The measured value can then be used in the second setting circuit.

In relation to the cover 110 (figure 1), it is watertight, or semi-permeable, depending on local requirements and regulations. Advantageously, a watertight cover allows to use a major depression, thus extracting more biogas.

Preferably, the collector depression Pr is greater than or equal to the internal depression Pi of the manure mass, which ensures that methane is not thrown into the atmosphere.

The invention can be used notably, according to two modes of exploitation.

In a first mode of exploration, the aim is to enhance biogas, that is, to achieve a constant methane rate in the extracted gas, and to achieve a maximum flow (concentration χ flow).

Advantageously, biogas extraction greatly limits the spread of methane on environmental land.

In a second mode of operation, for the end-of-track locations and comprising the compartment (s) according to the invention, methane extraction flow (flow rate) may be maximized, in particular for safety issues, and gas with narrowing effect, ensuring a minimum methane content necessary for the operation of a chandelier.

Thanks to the invention, the set of control systems (regulation circuits) that anticipate internal / external disturbances allows to maintain a constant biogas quality over time.

Thanks to the invention, the methane flow extracted from biogas can be maintained at a predetermined value.

Claims (9)

1. A biogas extraction control process for a compartment (50) equipped with at least one extraction set (3IA, 31B), each extraction set being connected to a respective manifold (70A, 70B) via a flow valve. respective control (10A, 10B) and comprising at least one unitary extraction device (311A, 312A, 313A, 31B), the process comprising the steps of: - providing a respective predetermined manifold pressure (Pr) to each collector (70A, 70B); and - opening the control valve (10A, 10B) in a specified position, further comprising the steps of: - measuring the value of a weather parameter external to the housing; calculate a global pressure differential password (dPci) as a function of the value of the measured meteorological parameter; - measure the relative pressure (dPi) at least one extraction set; - compare the relative pressure measured to the password value (dPci); and change the position of the control valve (10A, 10B) as a result of the comparison result. A method according to claim 1, further comprising a step comprising: providing a first local password (dPcil) by comparing the value of the measured meteorological parameter (s) to a reference model; - the step of calculating the global password (dPci) being a function of this first local password (dPcil). Process according to Claim 2, characterized in that the measured external meteorological parameter is comprised in the set comprising atmospheric pressure, external temperature and rainfall. Method according to any one of claims 1, 2 or 3, further comprising the steps of: - measuring the value of an internal setpoint comprised in the set (02 / CH4 / CO2 content, temperature , pressure) at the level of at least one extraction set; - compare the measured value to a reference value; and - provide a second local password (dPci2) depending on the result of the comparison; - the global password (dPci) calculation step being a function of this second local password (dPci2). Method according to any one of claims 2, 3 or 4, characterized in that the reference model is constructed by a prior learning step, in which the evolution of the internal pressure in the compartment waste mass is measured as a function of of the value of the external / or internal parameter (s) measured. A biogas extraction control device capable of applying the process of any of claims 1, 2, 3, 4 or 5, the device comprising: - a housing (50) equipped with at least one extraction assembly (31A, 31B ), each extraction assembly being connected to a respective manifold (70A, 70B) via a respective control valve (10A, 10B) and comprising at least one unitary extraction device (311A, 312B, 313A, 31B), - means for providing a manifold pressure (Pr) to the respective manifold (s) (70A, 70B); means for opening the control valve (10A, 10B) in a given position, further comprising: means for measuring the value of a weather parameter external to the housing; means for calculating a differential pressure global password (dPci) as a function of the measured meteorological parameter value; means for measuring differential pressure (dPi) at the level of at least one extraction set; means for comparing the relative pressure measured to the password value (dPci); and - means for effecting a change of position of the control valve (10A, 10B), depending on the result of the comparison. Device according to claim 6, further comprising: - means for providing a first local password (dPcil) by comparing the value of the measured weather parameter (s) to a model reference, the global password (dPci) calculation step being a function of this first local password (dPcil). Device according to claim 7, further comprising learning means configured to measure the evolution of internal pressure (Pi) as a function of the value of the external meteorological parameter (s). ) measured (s), the reference model being built from the means of learning. Device according to any one of claims 6, 7 or 8, further comprising: - means for measuring the value of an internal physicochemical parameter comprised in the set (02 / CH4 / CO2 content) at the level of at least one extraction set; means for comparing the measured value to a reference value; and means for providing a second local password (dPci2) as a function of the comparison result, the global password (dPci) being a function of that second local password (dPci2).