BE1029533B1 - Autonomous in-situ floor heating system by thermal desorption - Google Patents

Abstract

The invention consists of an autonomous heating system (or unit) equipped with indirect tracer sensors that can be used in the field of soil remediation by thermal desorption using several heating systems. The sensors, coupled with system modeling allowing anticipation of depollution needs, make it possible to better monitor treatment compared to current systems and thus reduce treatment times and costs. The remote control of the heating system takes this additional information into account and each heating unit is controlled according to the measurements of its direct environment, making it possible to carry out an effective treatment notwithstanding the heterogeneity of the medium to be treated.

Description

Autonomous in situ floor heating system by thermal desorption BE2021/0046

DESCRIPTION FIELD OF THE INVENTION The invention consists of an autonomous heating system (or unit) equipped with indirect tracer sensors that can be used in the field of soil remediation by thermal desorption using several heating systems. The sensors, coupled with system modeling allowing anticipation of depollution needs, make it possible to better monitor treatment compared to current systems and thus reduce treatment times and costs. The remote control of the heating system takes this additional information into account and each heating unit is controlled according to the measurements of its direct environment, making it possible to carry out an effective treatment notwithstanding the heterogeneity of the environment to be treated.

BACKGROUND OF THE INVENTION Soil contamination is a problem of great importance in a world where | environment and sustainable development are becoming more and more important. This problem, often invisible, can be caused by a wide variety of chemical, biological or even radioactive contaminants and an equally wide range of pollution sources. Left as it is, the contamination can spread and end up in other resources essential to the surrounding flora and fauna. It is therefore important, in order to protect the environment and public health, to eliminate these contaminants before they become too | great repercussions.

Soil remediation technologies are multiple and can be separated into three main categories: thermal, biological and physicochemical. The choice of technique depends on several parameters such as the nature of the contamination, the properties of the soil, the physical constraints of the site and the total cost of the project. | One of these techniques, thermal desorption, is based on the heating of the ground to volatilize the contaminants and allow their extraction and destruction or reuse after recovery (for example, by simple condensation). Thermal desorption is effective against organic contaminants, cyanides, mercury and any other component that can be volatilized at temperatures below 550°C.

Heating via thermal conduction is one of the techniques used in the field of thermal desorption (WO2001078914A8). With this technique, the energy coming from the heating tubes propagates radially in the ground by conduction. This has several advantages vis-à-vis the other possibilities of soil remediation because thermal conduction makes it possible to heat the soil to temperatures exceeding 350°C (which is not possible, for example, with electric heating). resistive (US5656239A) and to easily and quickly treat soils contaminated by a wide variety of contaminants, regardless of the heterogeneity of the soil.Indeed, the thermal conductivity has the particularity of not fluctuating by large orders of magnitude with the composition of the soil.Therefore, thermal conduction is much more efficient than other methods of heat transfer in the case of heterogeneous soils.

This technique is applicable ex-situ and in-situ. In ex-situ thermal desorption, excavated soil is used to form piles or placed in containers which are heat treated. With /n-situ thermal desorption, heating tubes are inserted directly into the polluted soil, thus avoiding the excavation and transport of soil. This also makes it possible to treat soils in restricted places and/or with limited access such as remote sites, sites in urban areas, basements of houses, etc. In general, this technique is faster and has a reduced environmental impact.

Current thermal desorption techniques are based exclusively on measuring the temperature of the ground at its coldest point to estimate the progress of the remediation process. Once the contaminant volatilization temperature has been reached, if this is maintained for several days and sufficient suction is present in the soil, the contaminants will be eliminated with near certainty.

However, this conservative approach ignores all the mechanisms that can take place during heating and accelerate remediation. For example, the so-called steam stripping phenomenon occurs when the water vapor vaporized at the start of heating draws part of the contaminant out of the ground. A thorough and continuous analysis of the characteristics of the soil as well as the vapors generated makes it possible to take these mechanisms into account. In this way, the heating can be interrupted in advance, leading to a reduction in fuel consumption, a reduction in the total duration of the treatment and therefore ultimately a reduction in the cost of the treatment.

The heating systems which comprise the heating tubes described previously independently generate the thermal power transmitted to the medium to be treated. This thermal power setpoint can be chosen and adapted remotely, and independently for each heating point in order to take into account the heterogeneity of the medium to be treated.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an illustration of the complete heating system, including the control and analysis boxes.

Figure 2 is an illustration of several heating systems used for the treatment of contaminated soil Figure 3 is an illustration of the installation of different sensors used in the 40 measurement box.

3 . BE2021/0046

LEGEND OF FIGURES

1. Heating tube

2. Steam pipe

3. Vapor analysis unit

4. Soil analysis box |

5. Measuring tube

6. Control box |

7. Antenna

8. Medium to be treated

9. VTU valve

10. Reburn valve

11. Cross

12. Flexible

13. Cable gland

14. Acquisition circuit board ==

15. Vapor analysis sensors

16. Waterproof tube

17. Power Socket DETAILED DESCRIPTION OF THE INVENTION; The invention is the addition of a coherent and coordinated set of sensors making it possible to carry out in real time, advanced analyzes of the process allowing an instantaneous evaluation of the progress of the treatment as well as a new control box independently controlling each system. heating according to a setpoint defined remotely. The sensors are used to carry out so-called indirect measurements insofar as these are not a simple immediate measurement of the quantity to be regulated. Indeed, it is rather __ indirect tracers that are analyzed and are not directly related to the power deployed at a | instant given by the heating device. The sensor data is inserted into a model of the depollution process as a whole in order to obtain predictions on its progress. The model used takes into account the prediction errors between the expected results and the reality, in order to refine and improve the quality of the modeling on a permanent basis. The invention therefore consists of a heating system with adjustable power in real time coupled with the anticipation of depollution via a model in perpetual evolution. 40 Similarly to the prior art, a heating tube (1) is inserted into the medium to be treated (8). In a preferred embodiment, this heating tube (1) contains circulating air that can reach a temperature between 500 and 1900°C, making it possible to generate between 3 and 80 kW of thermal power to be transferred to the medium (8 ) by thermal conduction. The vapors generated by the heating are captured by a tube called the vapor tube (2), placed next to the heating tube (1). In a preferred embodiment, the vapors are routed from the vapor tube (2) to a cross (11) via a hose (12).

Alacroix is connected to the vapor analysis unit (3). This box includes all the electronic equipment necessary for the analysis of vapors coming from the ground.

In a preferred embodiment, the non-exhaustive list of the following quantities is measured: the CO concentration, the concentration of flammable gases, the concentration of volatile organic components, the concentration of hydrocarbons, the moisture content of the vapours. It is possible to add measurement quantities depending on the type of contaminant treated. The box is able to communicate in a wired or wireless way with the control box (6). It is also possible to integrate the electronic equipment directly into the control box (6), insofar as the sensors are always brought into contact with the vapours.

In a preferred mode of application, the cross is connected to two valves: the reburn valve (10) and the VTU valve (9). If the contaminant can be used as fuel, the reburn valve (10) is opened to reinject the vapors into the heating circuit. If the contaminant cannot be used as fuel, the VTU valve (9) is opened so that the vapors are routed to appropriate treatment units. In all cases, the vapors are — analyzed by the vapor analysis box (3).

In a preferred mode of application, the soil analysis box (4) includes all the electronic equipment necessary for the continuous analysis of the properties of the medium to be treated. In a preferred embodiment, the non-exhaustive list of the following quantities is measured: resistivity of the medium, pH of the medium, humidity of the medium. It is possible to add other measured quantities depending on the application. The box is able to communicate in a wired or wireless way with the control box (6). It is also possible to integrate the electronic equipment directly into the control box (6), insofar as the sensors are always brought into contact with the treated medium. The sensors can be brought into contact with the ground via a measuring tube (5) inserted into the ground.

In a preferred embodiment, the vapor analysis box is composed of a sealed tube (16) passing through the box. In this tube are inserted the vapor analysis sensors (15) which can be connected to the acquisition printed circuit (14) by removable connectors for increased ease of assembly and maintenance. Cable glands (13) make it possible to seal the connections to the outside, in particular the power supply socket (17). In contexts where electric power is limited, the system can also operate on batteries (rechargeable or not).

5 The control box (6) includes all the electronic equipment necessary for collecting data from the vapor (3) and soil (4) analysis boxes. The communication between the different boxes can be done in a wired or wireless way using standardized or proprietary communication protocols.

It is also possible to concentrate the electronic vapor and soil analysis equipment in the control box (6). The control box (6) also includes the electronic equipment allowing the regulation of the heating.

In a preferred embodiment in which the heating tube circulates air heated by the combustion of natural gas, the box must in particular control the flow rates of combustion air, the flow rate of natural gas, the injection pressure .

In order to be able to be controlled remotely, the control box (6) is equipped with a wired or wireless communication protocol.

In a preferred embodiment, the analysis boxes (3,4) as well as the control box (6) communicate via a local network such as Bluetooth, Wi-Fi or LoRa.

Other devices on the same network allow on-site operators to have direct access to data and enable fine-grained, real-time monitoring of treatment, even in the event of an internet connection failure (which can happen frequently in isolated places where depollution sites sometimes take place). A gateway makes it possible to connect the local network to the Internet, and to centralize the data towards a dedicated server for analysis.

Once the data: examined and interpreted (by specialized algorithms or by human intervention), heating instructions are generated and transmitted back to the control boxes.

This operation of exporting data, analysis, setpoint then regulation can be carried out entirely autonomously.

This communication with the control system can be carried out in a local area network (WLAN) and possibly connected to the Internet via a gateway.

In a preferred embodiment, the control (6), vapor (3) and soil (4) analysis boxes are made in such a way that they can be deployed outside.

It involves being | moisture and dust resistant.

By way of example, an index of protection against solids and liquids (international standard as defined by European standard EN 60529) IP56 is recommended, signifying effective protection against dust, microscopic residues and strong jets of water from all directions.

Thermal insulation is also necessary in order to guarantee the proper functioning of the electronics near the heating systems.

In order to increase the communication range, it may be necessary to add an antenna (7) outside the box.

This antenna becomes systematically necessary in the case where the box is made of metallic material.

Claims (4)

; ; BE2021/0046 CLAIMS; 1. Autonomous heating system equipped with indirect tracer sensors in which the indirect sensors are linked directly or indirectly to the combustion elements such; ; as fuel solenoid valves, primary air valves or management fans | of combustion stoichiometry, in which the sensors, coupled with a modeling of the system allowing an anticipation of the needs for depollution, allow a management | ‘or treatment follow-up. 2. System according to claim 1 where the remote control of the heating system takes this additional information into account and each heating unit is controlled according to the measurements of its direct environment, making it possible to carry out an effective treatment notwithstanding the heterogeneity of the medium to be treated. 3. Autonomous heating method equipped with indirect tracer sensors in which the indirect sensors are linked directly or indirectly to the combustion elements such as the fuel solenoid valves, the primary air valves or the combustion stoichiometry management fans, in which the sensors, coupled with a modeling of the system allowing an anticipation of the needs of depollution, allow a management or a follow-up of the treatment. To 4. Method according to claim 3 where the remote control of the heating system takes this additional information into account and each heating unit is controlled according to the measurements of its direct environment, making it possible to carry out an effective treatment notwithstanding the heterogeneity of the medium to be treated.