Monitoring and shaping the thermal processes of the Detritiation Pilot Plant using infrared thermography

Size: px

Start display at page:

Download "Monitoring and shaping the thermal processes of the Detritiation Pilot Plant using infrared thermography"

Joshua Potter
5 years ago
Views:

1 Monitoring and shaping the thermal processes of the Detritiation Pilot Plant using infrared thermography SORIN GHERGHINESCU National R&D Institute for Cryogenics and Isotopic Technologies (ICIT) code Rm. Valcea, Uzinei 4, CP7 Riureni, Valcea, ROMANIA, phone: , fax: , sorin@.icsi.ro ; sorin70g@yahoo.com; Abstract: Infrared thermography (IR) is a nondestructive inspection technique that can pinpoint control parameters covered applications in industrial systems, heating systems, electrical and mechanical systems. A professionally managed MP program can identify impending failures in the thermal and electrical equipment and machinery production. These programs can prevent interruption of production and increases security of nuclear facilities in operation as analyses developed in this works. All objects emit thermal energy (heat) in the form of electromagnetic radiation in the IR spectrum. A hotter object emits intense infrared radiation. This radiation is, however, outside the range observed by the human eye. IR thermography is used to detect, through pictures, this measure of radiation emitted. By detecting areas of abnormal temperature, infrared thermography can diagnose problem areas and their severity. Paper refers to thermographic analysis of purification systems used in the experimental Pilot Plant for Tritium and Deuterium Separation(PTDS). To assess the integrity of research has been directed primarily to obtain the reference set of thermal images, and secondly, the examination of samples before and after thermal stress during operation. The conclusions highlight both the optimal examination schedules, parameters and limits of applicability of thermographic inspection in thermal systems of the PTDS. Keywords: nondestructive inspection; infrared thermography; cryogenic systems. 1. Introduction A thermography system, leading to a visible image in the distribution of the visible light output is proportional to the flux distribution of infrared radiation emitted by the object examined or spatial distribution of temperature, T (x, y), or emissivity, ε(x, y). This transformation may be achieved through sequential analysis of various parts of the object or scene thermal radiometric elementary through a field, E, or by using an array of detector elements. Modern IR cameras offer detailed photos showing each item of equipment in operation "heat signature". Increasing the temperature above normal operating temperature provides a good indicator of the severity of problems, such as an overload or imbalance, corrosion, or bad connection. This profile heat, properly interpreted, can reveal a great problem which may occur during the lifetime of the inspected equipment. Identification and assessment of steel structures exposed to thermal stress, based on nondestructive examination methods may be characterized by a continuous evolution of these techniques, but also by developing software systems for detailed analysis of thermographic images. Compared with other nondestructive methods of inspection applicable to the materials, to assess the integrity of the pipes joined by welding or brazing, infrared thermography (IRT) has as main advantages: high-speed examination, inspection from a distance, without direct contact with product review clean and safe, clear fault indications, outlining areas of effective thermal gradient in image format. The main current trends in the development of infrared termography as a method of nondestructive examination are: - Development of equipment: the diversification of constructive solutions, miniaturization and specialization of radiometer rooms, including modern IT components in the construction of IR cameras, improving the quality of detection elements, based on modern nanotechnology and extend the spectral sensitivity bands by using new types of detectors, elimination of traditional ISBN:

2 cooling systems, association with IR cameras sensitive in visible cameras. - Developing specialized software: remote control equipment, recording information, thermal imaging, computerized image interpretation and fault indications, facilitating the creation of data banks. - Development of theoretical principles of physical and mathematical modeling to reconstruct defects in the quantitative assessment. - Combination of thermography with other nondestructive examination methods for increasing reliability and reducing the results of an evaluation of measurement uncertainty in estimating the size of defects. - Design and implementation of international rules specific to various areas of applicability of thermography. In the technical field, passive thermography applications objectives can be grouped into the following categories: - Applications for surveillance and monitoring of production; - Quality control for deciding pass / fail; - Predictive maintenance to report early dysfunction that could lead to accidents, explosions, fires, etc. - Research and environmental activities. 2. System analysis Pilot Plant for Tritium and Deuterium Separation developed the cryogenic technology of tritium separation from tritiated heavy water. The process is based on an catalyzed isotopic exchange module, where the tritium is extracted from tritiated heavy water. An important process in this way is to extract moisture from the wet hydrogen gas coming from the exchange column. Monitoring of process parameters was done by two methods, infrared thermography and thermocouple type k with the computer data acquisition system via USB 2.0 interfaces. In Fig. 1 presents the simplified scheme of purification system that contains two adsorbers (C201A, C201B) and a water-antifreeze mixture condenser (H202) connected to a chiller system fully automated. Fig.1. The purification system. 3. Theoretical approach In the process of adsorption in dynamic conditions, one has to determine the efficiency of sorbent material corresponding to breaking concentration. Efficiency is defined as the ratio between the amount of water retained by the adsorbent material and the quantity of adsorbent material, and is known as adsorption capacity: ( c cr) m tr a= 0 M (1) where a - adsorption capacity (g / kg); c 0, c r - input concentration, break (% vol); m - effluent flow (m 3 / s) t r - during the break (s); M - the amount of adsorbent (kg). In scientific literature there are several theories and relationships that describe the steady state gas-solid system, mostly based on empirical or semiempirical tests. All these models do not explain in rigorous manner the experimental observations. Langmuir concluded the following equation for the adsorption isotherm 1 : x X m k bp = = a (2) 1+ bp where: X, the adsorption capacity in kg / kg; x, the amount adsorbed, kg; m, amount of adsorbent, kg; p, equilibrium partial pressure of component; k a, b, isothermal specific constant. 1 ISBN:

For determining the partial pressure of vapor can use the following equations 2 : p w (t) = 6.112 exp [17.62 t/(243.12 + t)][mbar] (3) p i (t) = 6.112 exp [22.46 t/(272.

Experimental results During the experiment, measurements were made on concentration of the sorbent layer at different temperatures to determine the saturation and breaking curves.

3 For determining the partial pressure of vapor can use the following equations 2 : p w (t) = exp [17.62 t/( t)][mbar] (3) p i (t) = exp [22.46 t/( t)] [mbar] (4) where w and i are indices for water and ice Fig. 2. Partial vapor pressure below 0 0 C. 4. Experimental results During the experiment, measurements were made on concentration of the sorbent layer at different temperatures to determine the saturation and breaking curves. Knowing the gas flow and water, which is an impurity of gas, one can determine the amount of water to be retained on the adsorbent material (13X molecular sieve) in a given period. m= ( c0 cr) D0t (5) 0 After the adsorber reaches saturation, it requires the regeneration, which will be repeated after each cycle of adsorption. The regeneration process involves, in fact, an operation which is accomplished by increasing the desorption temperature of the gas flow and its pressure drops below the pressure at which adsorption occurs. This operation is conducted in two stages: first heated gas flow free of impurities (gas resulting from the adsorption process) backwards through the adsorber to be regenerated, adsorbent who is making the removal of water from the pores of the adsorbent material, and the second stage, when the material is cooled to be brought to the necessary conditions for the adsorption; this time it is no longer heated. Studies conducted by the ICIT on adsorption process allowed to develop a method of designing an adsorber. For certain inputs, like flow, pressure, temperature, concentration and duration of the process were obtained data on the diameter and length of the adsorber. Using sorbent in a large number of cycles, each job requires the regeneration after adsorption. Therefore, gas purification by adsorption involves two successive operations: - adsorption, in which some components of the mixture are retained on the sorbent mass; - desorption, which recovers the adsorbed substance and regenerates the adsorbent. To achieve the desorption process there can be distinguished several ways: - heating: - reducing the pressure of the system; - inert gas stripping. validate the theoretical results, we developed the experimental tests where was measured the dew point during the all set of experiments. Fig.3. Experimental values of dewpoint. Dew point to C corresponds to a total value of 5 ppm moisture. Using the equation [5], corresponding to C, we obtain 5 ppm, the value of humidity concentration. This is a good correlation with experimental value, and an acceptable value for the adsorption system objectives. 2 World Meteorological Organization (WMO) Web Site ISBN:

Fig. 4. Infrared image around the outer surface of the adsorber. Fig. 6. Data acquisition system.

Conclusions The experiments indicate that after 20 hours the dew point remains constant (-65.5 0 C Fig.

Experimental data are comparable with those in the scientific literature 3. Fig. 5. Infrared image (at high temperature) around the outer surface of the adsorber.

To study the efficiency of the cooling system with liquid nitrogen during the purification phase, infrared thermography was used. Thermograms obtained (Fig.

4 Fig. 4. Infrared image around the outer surface of the adsorber. Fig. 6. Data acquisition system. Acquisition system is composed by thermocouples K type, temperature measurement system with compensation of cool points and the specialized computer software for data acquisition via USB interface. 5. Conclusions The experiments indicate that after 20 hours the dew point remains constant ( C Fig. 3), and that explained the fact that in those conditions of temperature, flow and pressure the thermodynamic equilibrium is achieved. Experimental data are comparable with those in the scientific literature 3. Fig. 5. Infrared image (at high temperature) around the outer surface of the adsorber. External cooling system to adsorber is made of a copper coil with a length of 40 m, which makes heat transfer up to 2 kw. To study the efficiency of the cooling system with liquid nitrogen during the purification phase, infrared thermography was used. Thermograms obtained (Fig. 4 and 5 indicate different points of temperature) give important information about the transfer of heat uniformity around the outer surface of the adsorber. The scans during the cooling process and we see the tensions that arise due to thermal deformations. In conclusion, infrared thermography method provides information on the execution stage of the cooling system of the adsorber. Fig. 4. Desorption time variation with the nitrogen flow. Funding Acknowledgement: This publication was made possible by Project PN II/2008 number 22139, from the National Authority for Scientific Research (ANCS). 3 er_en.pdf ISBN:

5 References [1] Xavier MALDAGUE, NDE of Materials by Infrared Thermography, Springer, 300 p. Germ [2] H. KAPLAN, A thermographer's guide to infrared detectors, FLIR Systems Inc., 12 p., Boston, [3] Gregory STOCKTON, Beyond the Usual Application for Infrared Thermography, Stockton Infrared Thermographic Services, 4 p., SUA, [4] ASTME 168 (1999), Standard practices for general techniques of infrared quantitative analysis. [5].Sorin Gherghinescu, Efficiency of multilayer insulations in cryogenic applications. The 3rd International Conference on ENVIRONMENTAL and EOLOGICAL SCIENCE and ENGINEERING (EG'10), p , ISSN: , ISBN: [6] Sorin Gherghinescu, Gheorghe Popescu, 2010, Reduced Power Consumption in Atmosphere Detritiation System (ADS) for Sustainable Development. Institute for Environment, Engineering, Economics and Applied Mathematics, International Conference on DEVELOPMENT, ENERGY, ENVIRONMENT, ECONOMICS (DEEE) Puerto De La Cruz, Tenerife, Spain, ISBN: , p ISBN:

Data acquisition system for optimization and control of the processes from an isotopic exchange column

Data acquisition system for optimization and control of the processes from an isotopic exchange column C. M. Retevoi, I. Stefan, A. Bornea & O. Balteanu National Institute of Research-Development for Cryogenic