MXPA00009367A - Methods and apparatus for monitoring water process equipment - Google Patents

Abstract

Methods and apparatus are provided for detection of leaks in boilers (10) containing a temperature control liquid (12) which is supplemented with feedwater and removed as blowdown. The methods include measuring rates associated with the feedwater supplementation and blowdown (18), adding a tracer to the temperature control liquid, determining the change in rate of the feedwater supplementation, determining the mass of the temperature control liquid, deriving the change in concentration of the chemical tracer in the temperature control liquid, calculating the unaccounted for water rate and comparing this rate with zero to determine if a leak condition is present.

Description

METHODS AND APPARATUS FOR SUPERVISING THE WATER PROCESSING EQUIPMENT FIELD OF THE INVENTION The present invention relates to methods and apparatus for supervising industrial water processing equipment. More specifically, the invention is directed to the detection of leaks in the water processing equipment as black liquor recovery boilers.

BACKGROUND OF THE INVENTION A boiler is an apparatus in which water or some other aqueous liquid to which replacement water is added and from which purged water is removed, is evaporated in steam by application of heat from an oven or system. of heat generator process. In most cases, the liquid for temperature control is brought into close, indirect contact with the process system to facilitate heat transfer. The leakage in a boiler can give origin not only to contamination and incrustation of the liquid for the control of the temperature and the system of the process, but also to unwanted physical reactions. This is particularly true for boilers for the recovery of the black coil that is used in multiple paper mills. In the boilers for the recovery of the black liquor, the escape or leakage of the aqueous liquid for the control of temperature from the inner surface of the water circuit of the boiler towards the "face exposed to the fire" highly caustic, hot can cause violent explosions. The prior art provides numerous techniques for monitoring and controlling boiler leaks for recovery of black liquor and other boiling systems. These methods use diverse techniques, mainly two classes of methods of mass balance, mass balances of the chemical tracer and water. For example, U.S. Patent No. 5,363,693 to Nevruz, teaches methods and apparatus for detecting leakage from boiling systems for recovery using mass balance of the water flowing in and out of the boiler. The method then calculates the long-term and short-term statistics for the cylinder or drum balance of the mass flow. From these calculations a function of the test t is evaluated to observe if the average of the long-term and short-term movement of the drum equilibria are significantly different, which in turn indicates whether a leak occurs in the boiler. Although water mass balance leak detection systems can be effective, as described in U.S. Patent 5,663,489 (Thungstrom et al), these are generally less sensitive than chemical trackers systems and do not discriminate between leakages in portions. critical and not critical of the boiler. U.S. Patent No. 5,320,967 (Avallone et al) is an example of another method of mass balance, namely, chemical trackers. Avallone describes a method of leak detection in the boiling system that includes introducing an inert tracer to the boiler in a known and uniform proportion in the feedwater, detecting a characteristic of the tracker in the boiler in the steady state, converting the characteristic detected in a value equivalent to the concentration of the tracker in the liquid for temperature control, and activating a signal when there is an excessive variation in the concentration of the tracker. However, the method described by Avallone et al is limited by its requirement that the tracer be detected (registered) when the boiler is in the steady state, which is said to occur only when there is no significant change in any of the five parameters of the process: the concentration of the tracker in the boiler; the speed of the amount of water purged, the speed of the feed water; the feeding speed of the tracker to the boiler; and the speed of the steam in the absence of leakage in the boiler. U.S. Patent No. 5, 565, 619, by Thungstrom et al., Teach the methods and apparatus for monitoring leaks in boilers. The methods use a tracer compound that is added to the water in the boiler at a rate proportional to the velocity of the water purged. The expected concentration of the tracer leaving the boiler is calculated using variables under non-equilibrium conditions and compared with the actual concentration of the tracer in the purged water. If there is a statistically significant difference between the actual and expected concentrations, a leakage condition is indicated. Although this chemical tracer method is an improvement over Avallone's in that the boiler does not need to be in the steady state to detect leaks, two aspects related to this method have been discovered. First, this method assumes that the mass of the water in the boiler is constant as the steam load changes. With very small leaks, changes in the mass of the boiler water with load changes can lead to false alarms due to changes in the concentration of the tracker. Second, it is difficult to apply statistical methods to the output data of the method. Accordingly, a leak detection system based on a chemical tracker is required in the art which does not assume that the mass of the water in the boiler is constant and that it can operate with an automatic water level controller. In addition, there is a need for a leak detection system based on a chemical tracer whose results can be used with statistical methods.

COMPENDIUM OF THE INVENTION The present invention offers the methods and the apparatus for the detection of leaks in boilers to which liquid is added for temperature control and from which liquid is eliminated. The liquid for temperature control is supplemented with feed water and eliminated as purged water. These complementation and elimination speeds are measured; the mass of the liquid in the boiler is calculated. In a preferred embodiment, a chemical tracer substance is added to the liquid for temperature control, and its concentration in the feed rate [sic] and purged water is measured. By determining the change in the rate of feedwater supplementation and the change in the concentration of the chemical tracer in the boiler water, these numbers can be combined with measurements of velocity, mass and concentration to determine the water rate that is lost in the network (that is, it leaks).

BRIEF DESCRIPTION OF THE DRAWING The attached Figure 1 is a schematic representation of a boiler monitoring system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention offers the methods and apparatus for detecting a leak in a boiler having an automatic control mechanism of the level of the liquid in which a liquid for temperature control in a containment means is supplemented with feed water and it is separated as purged water, it comprises the steps of: a) measuring a rate associated with the addition of a chemical tracer to the liquid for temperature control; b) measure the concentration of the chemical tracer in the liquid for temperature control; c) measure a rate associated with the purged water; d) measure a rate associated with the supplementation of the feedwater; e) determine the change in the rate of the supplementation of the feedwater by taking the derivative of the supplementation of the feedwater with respect to time; f) determine the mass of the liquid for temperature control in the containment medium; g) determine the change of concentration of the chemical tracker in the liquid for temperature control by taking the derivative of the concentration of the chemical tracer with respect to time; h) determine the rate of water lost in the network by dividing the rate obtained in step (a) with the concentration obtained in step (b), and subtracting from this determination the rate obtained in step (c), the change of the rate obtained in step (e) and the mass obtained in step (f) multiplied by the change in concentration obtained in step (g) divided by the concentration; (i) compare the rate of water lost in the network with zero; and (j) indicate a leakage condition if the rate of water lost in the network is significantly greater than zero. The present invention also offers the apparatus for detecting leaks in boiler systems. The apparatus according to the present invention consists of: a) the measuring means in communication with the addition means of the chemical tracer; b) the means for determining the concentration in communication with the liquid for temperature control; c) the measuring means in communication with the water purge means; d) the measuring means in communication with the supply water supplementation means; e) the derivation means in communication with the addition means of the feed water to derive the change in the rate of the feed water with respect to time; f) the means for bypassing the mass in communication with the purge means, adding the chemical tracer and determining the concentration; g) the derivation means in communication with the means for determining the concentration of the chemical tracer to derive the concentration change with respect to time; h) the means for determining the rate of water lost in the network in communication with the addition means of the chemical tracer, the means for determining the concentration, the means for measuring the purged water, the means for deriving the change in the rate of feed water, the means of derivation of the mass and the means for the derivation of the chemical tracer; and i) the means of comparison in communication with the medium that determines the water rates lost in the network to determine if there is a leak. The methods and apparatus of the present invention can be used to monitor almost any type of equipment to which liquid is added and from which liquid is removed. The methods and apparatus of the invention are preferably used to monitor boilers, especially boilers to recover black liquor. Representative boilers are described in U.S. Patent Nos. 3,447,895 (Nelson et al), 4,462,319 (Larson), 4,498,333 (Parthasarathy) and 4,502,332 (Tero), the contents of which are incorporated herein by reference. An exemplary monitoring system according to the invention is shown in Figure 1, wherein a first containment means ("the inner surface of the water circuit") or "boiler" 10 containing the liquid for temperature control 12 it is adjacent to and in thermal communication with a second containment means ("the face exposed to fire") 14 which normally contains hot vapors and a molten bed. The boiler 10 is in hydraulic communication with the pipe of the purged water 18 for the discharge of the purged water towards the discharge outlet 20 and with the steam pipe 22 for the discharge of the steam towards the condensation means 24. The discharge of the purged water it is controlled through the activation of the purge valve 26, which can operate manually or with the control of an external computer or some other means of processing (not shown). It is not necessary that the purge valve be under the control of the system of the invention. Between the boiler 10 and the valve 26, the purge pipe 18 is in hydraulic communication with the monitoring means 34 to provide information on the flow rate of the purged water. Downstream of the valve 26, part of the flow of the purged water is diverted to the cooling medium 30 for sampling and analysis. The measuring means 32, such as an in-line analyzer based on UV / visible spectroscopy, is located downstream of the cooling medium 30 to provide the means for determining the concentration of the tracker in the purged water. The measuring means 32 and 34, in turn, are in electrical communication with the processing means 38. The purged water flow monitor 34 can use any number of flow meters designed for high temperature liquid including plate meters of holes, vortex emission meters, flow nozzle meters, venturi meters, strain or strain gauges, Doppler meters (transit time) turbine meters, magneto meters and pitot devices. The cooling medium 30 can be any number of sample coolers with sufficient cooling water flowing therethrough to reduce the temperature of the sample water to the environment. The selected measuring means 32 depends on the tracker that is used. For example, with a molybdate tracer it is possible to use an FPA 800 analyzer manufactured by Tytronics (Altham, MA) otherwise, if a phosphate is used as a combined tracer and chemical treatment, a Hach phosphate analyzer can be used (Loveland, CO ) series 5000. The boiler 10 is also in hydraulic communication with the source of the feed water 36 through the feed pipe 38. As shown in Figure 1, the feed pipe 38 is in hydraulic communication with the source of the water. tracker 40 through the chemical feed pipe 42. Otherwise, the source of the tracker 40 is directly coupled to the boiler 10 through the chemical feed 44. In any mode, the absolute amount of the tracker added to the boiler 10 is controlled and recorded in the processing means 28. The source of the tracker 40 may contain the tracker or a mixture of the tracer and other chemicals of treatment to be fed to the boiler. Downstream of the source of the tracker 40, an apparatus for the measurement of the flow ("unit for descending level") 46 provides an accurate measurement and control of the flow of the tracker being injected into the feed water pipe 38 through a electric pump 48. The unit for the descent of level 46 and the pump 48 are in electrical communication with the processing means 28. The unit for the descent of level 46 offers a feedback signal to the processing means 48 which, in turn, controls the pumping speed of the pump 48 to ensure a verified feed of the chemicals to the feed lines 42 or 44. The processing means 28 and the unit for associated level descent 46 are preferably constructed in accordance with the teachings of U.S. Patent No. 4,897,797, assigned to the same assignee of this invention and incorporated by reference herein. During normal operation, the controlled addition of the feedwater to the boiler 10 compensates for the removal of the purged water and steam, and maintains a desired volume of the liquid for temperature control 12 within the boiler 10. In accordance with the present invention , the liquid for temperature control is also complemented by a known quantity of at least one tracker. The trackers according to the invention are organic and / or inorganic compounds which are soluble in the feed water, the liquid for temperature control and the water purged under the operating conditions. The trackers should also be stable to heat and not volatile. In certain embodiments, the selected tracer is a reactive chemical treatment added to the boiler for, for example, corrosion control or scale deposit. In other embodiments, the tracker is practically unreactive with (ie, inert to) the feedwater, the liquid for temperature control, the purged water, and the contact surfaces of the process equipment. It is preferred that the feedwater introduced into the process equipment upstream of the tracer injection is practically without the tracer, ie, that it contains less than about 0.002 ppm of the tracer and / or that it has a tracer concentration of less than about 1. % of the concentration of the liquid tracker for temperature control. The trackers according to the invention possess at least one physical property that allows their detection in samples of the purged water. Preferred trackers absorb and / or emit measurable amounts of light (or of the reaction products that absorb and / or emit measurable amounts of light) in proportion to the amount of the tracer present. Preferably, the trackers are detectable by at least one analytical technique selected from: electrochemistry, UV / visible spectrophotometry or fluorescence emission spectroscopy. Representative trackers include the trackers described in U.S. Patent Nos. 4,783,314 (Hoots et al), 4,966,711 (Hoots et al), 5,041,386 (Pierce et al) 5,200,106 (Hoots et al), 5,304,800 (Hoots et al) 5,320,967 (Hoots et al). Avallone et al), the contents of which are incorporated herein by reference. Preferred scavengers are chemical treatment compounds containing lithium and phosphate and transition metals, including salts, ions, oxy-anions, cations and metal complexes belonging to Group VII of the Periodic Table. Particularly preferred are compounds containing molybdenum, including molybdenum salts such as sodium molybdate. The trackers can be added to the liquid for temperature control in any of different ways. For example, solutions containing tracer can be added directly to the liquid for temperature control, these can be premixed with the feed water that is added to the liquid for temperature control or can be premixed with treatment chemicals and then added to the feed water. In general, the amount of tracer added must be sufficient to establish a concentration of the tracer from about 0.2 to about 20 ppm in the liquid for temperature control and, consequently, in the purged water. A natural consequence of steam generation in a boiler is a concentration of incoming components, non-volatile. To control this "swing" effect, one or more volumes of the liquid for relatively concentrated temperature control is usually removed from the boiler as purged water and corresponding volumes of the relatively dilute feed water are added. In accordance with the present invention, the purged water is sampled at known regular or irregular intervals or continuously monitored to determine the measured concentration of the tracer contained therein. This determination can be made, for example, directly or indirectly, by comparing the amount of light absorbed or emitted by the purged water with the amount of light absorbed or emitted by the standard solutions containing known concentrations of the tracer and other solutes that are They find in the water purged. Otherwise, the purged water is mixed with a reagent that reacts with the tracer and imparts a color to the purged water in proportion to its tracer concentration. The concentration of the tracer can be determined by comparing the color with the color of one or more standard solutions prepared by mixing solutions containing known concentrations of the tracer with the reagent. Previous chemical mass balancing methods that employ chemical trackers for leak detection have certain limitations. They only compare the calculated chemical concentration in the boiler and the actual actual reading. When a leak occurs, the current concentration reading will gradually fall until it reaches a predetermined limit that triggers the leakage alarm. The time required for this process is very long (6 hours or more). Another aspect is in false alarms caused by changes in the conditions of the boiler system. If the boiler is not operating under stable conditions such as during start-up, load oscillations and the like, the water mass of the boiler with change causes the concentration of the chemical tracer to be different from the calculated value and generates a false alarm. These effects will last for some time before normal operation for leak detection resumes. In addition, the previous chemical mass balancing methods did not allow the calculation of the size of the leak. The fundamental equation of chemical mass equilibrium is: d (M * Ch. = ChFd - (BD + LK) * Ch (1) dt where: M mass of water from the boiler Ch concentration of the chemical tracer in the boiler ChFd speed of feeding of the chemical tracker BD velocity of the purged water LK rate of the water that is lost in the network t time Taking the derivative on the left side produces: dM * Ch + M * dl £ ul = ChFd - (BD + LK) * Ch (1 ') dt dt In boilers with automatic control mechanisms for the level of the cylinder (or liquid level), the following relationship between the water mass of the boiler (M) and the feed water inlet speed (FW) is maintained: dM = b * d (FW, dt dt (2) where unit b is a unit of time and is a particular parameter for the individual boiler, b can be calculated using a least-squares adjustment on the historical data of the boiler, for example, the data of a month.

The insertion of equation (2) into the equation. { ! 'produces: b * d (FW) * Ch + M * d (Ch) = ChFd - (BD + LK) * Ch (2') dt dt LK * Ch = ChFd - BD * Ch-b d.FW) Ch IVT d (Ch) (3) dt dt Dividing the equation (3) between the concentration of the chemical tracer Ch, we have: LK = ChFd - BP - b * dfFW) - M * d.lp. Ch)) (3 ') Ch dt dt In practice, there may be mismatches between the measurements related to the flow of the chemical entering and leaving. This requires the introduction of a dimensional "a" factor to balance the entry of the chemical and the discharge of the chemical. Thus, equation (3 ') becomes: LK = a * ChFd - BD - b * d.FW) - M * dflnCh)) (4) Ch dt dt where a and b are parameters dependent on the boiler as well as the mass of the water in the boiler, M. the term can be determined from the measurement of the chemical tracer feed rate, the concentration of the chemical tracer and the velocity of the water purged under conditions without leakage, no load oscillation and the feed rate of the chemical tracer being stable for approximately 12 to 48 hours. Under these conditions, equation (4) is: 0 = a * £ hFd-BD Ch or a = BD * h (5) ChFd The term b is the delay time between the steam and the feed water, which can be calculated by looking for the delay time for the maximum correlation between the steam and the feed water. It is necessary to measure this data in non-leaking conditions and sufficient load oscillation (at least 50% of the normal vapor value, or 70% of its possible oscillation interval under normal conditions).

The term M is the nominal value of the water mass of the boiler. M can be calculated by introducing a leak with a fixed leakage rate, LK, while maintaining the boiler load and constant ChFd and BD without oscillation (which must be done after the term a has been calculated). As such, equation (4) becomes: M * d.Ch) = a • ChFd - (BD + LK) * Ch (6) dt The solution of Ch for the linear differential equation, of the first first order of: Ch (t) = a * Exp f-fBD + LK) • t) + a * ChFd (7) M (BD + LK) where a is determined by the initial condition of the equation (6) Ch.t) - a * ChFd Then ÍBD + LK) is set for an exponential function, a * Exp (ß * t). Comparing ß and - (BD + LK) / M you get: M - - (BD + LK) (8) ß Note that the term, Ln (Ch (t) -a * (ChFd) (BD + LK) can be adjusted to a linear function, A * t + B, then: M = - (BD + LK) / A (8 ') Notice that Ch (t) can also be adjusted to a sum of an exponential function to a constant, a * Exp (ß * t) +?. Then, M is determined by equation (8), but also: In addition, it is possible to simulate the leak by increasing the velocity of water purged by a fixed amount while maintaining without change ChFd and without oscillation the load of the boiler after the boiler has reached a steady state. In certain situations the chemical tracer can also be removed in the steam, as well as in the purged water. This can be considered in the methods of the present invention and incorporated in equation (4) by adding the rate of vapor removal to the velocity of purged water. If there are multiple flows of chemical substance in the effluent and / or effluent to / from the boiler, the method is generalized in the obvious way. During the initial period of many leak events, the concentration of the chemical in the purged water usually changes very little in response to leakage, due to the long time characteristic of the boiler system, M / (BD + LK). For these leaks, the leakage-induced change in undifferentiated terms of the chemical mass equilibrium equation will be relatively small and thus the signal to noise ratio of the chemical leakage indicator will be dominated by how well the derivative can be estimated. of the total chemical concentration in the boiler water, that is, d (M * Ch) / dt. Under these conditions, I can rewrite (4) as: LK = -b * d (FW) / dt - M * d (ln (Ch)) / dt = d / dt (-b * FW - M * ln (Ch)) In general, given any function discretely sampled, z (t) (in our case, z (t) = -b * FW-M * ln (Ch)), a common way to estimate its derivative is by using the differences backwards: z * (t) = (zi - z? _?) / dt Here dt is the time interval between the samples. Start by applying perhaps the simplest data filter, the equalization of the average moving weight to the sequence of that estimated derivative: Estimated Derivative i = Prom. Mov. ( { z ± - z ± - ±) / dt) = ((z ± - Zi _?) / dt + ... + (Zi- (N-i) - zi_N) / dt) / N Notice how all z-j's in the sum minus the first and last values are canceled. Thus, if only one movement average (individual filtering) of the first derivative estimates based on the difference is used, only information from the first and last points is obtained in our slope estimates. That is, any information that may contain the midpoints around the slope is discarded. Contrast this with an estimate of the slope based on a least squares adjustment of a linear trend to the original sequence z ± in which each point contributes to determine the slope. However, we can improve this situation if we feed the result of the sequence of this first moving average in a second moving average (double filtering): Best derivative estimate = moving average (moving average ((ZÍ ~ ZÍ_I) / dt)) = Prom. Mov. ((zi-Zi-ji) / (N * dt)) = ((Z ± + Zi-i + ... + Zi- (-1)) / N - (Zi_N + Zi_N_? + ... + Zi_N (N_ l)) / N) / (N * dt) Note that the above statistics can be interpreted as the difference between the moving average of N points and the same average of movement of the N point portrayed by the points N, divided by N * dt (the time between the centers of these two averaged windows) . Also note how, by using double filtering, all data points, not just the two points at the beginning and end of the data window, contribute to, and thus help reduce the variability of, our derivative estimate. The above statistics is a well-known "easy to calculate by hand" approximation of the slope of the "best fit" trend line for all 2 * N data points. However, the estimate of the previous slope, although more effective from the statistical point of view, is not, assuming white noise errors in z (t), as efficient as the estimate of the slope produced by a real least-squares adjustment . In practice, an exponentially weighted moving average (EWMA) is often used instead of an equal weighted moving average for the data filter. Although the analysis is somewhat more complicated with the EWMA, the main mechanism with which double filtering improves the estimates of derivatives, and therefore the detection of leaks, is the same. In addition, it can be shown that the EWMA double of a first derivative estimate based on the difference, instead of being just an approximation of a least squares slope estimate, is a least squares slope estimate, and thus, arguable, even more efficient in estimating the slope. The above methods do not recognize the importance of estimating the efficient derivative in the extraction of the leakage information contained in the data and by this way the increase in the signal-to-noise ratio and the improvement of the leak detection limits. Increases in the signal to noise ratio of two or more have been observed due to the use of this double filtering technique. Although this invention has been described with respect to the particular embodiments thereof, it is evident that numerous other forms and modifications of this invention will be apparent to those skilled in the art. The annexed clauses and this invention should generally be considered to cover all of these obvious forms and modifications that are within the true spirit and scope of the present invention.

Claims (21)

1. A method to detect a leak in a boiler having a mechanism of automatic control of the level of the liquid in which a liquid for temperature control in a containment medium is supplemented with feedwater and removed as purged water, consists of the steps of: a) measuring a rate associated with the addition of a chemical tracer to the liquid for temperature control; b) measure the concentration of the chemical tracer in the liquid for temperature control; c) measure a rate associated with the purged water; d) measure a rate associated with the supplementation of the feedwater; e) determine the change in the rate of the supplementation of the feedwater by taking the derivative of the supplementation of the feedwater with respect to time; f) determine the mass of the liquid for temperature control in the containment medium; g) determine the concentration change of the chemical tracer in the liquid for temperature control by taking the derivative of the concentration of the chemical tracer with respect to time; h) determine the rates of water lost in the network by dividing the rate obtained in step (a) with the concentration obtained in step (b), and subtract from this determination the rate obtained in step (c), the change of the rate obtained in step (e) and the mass obtained in step (f) multiplied by the change in concentration obtained in step (g) divided by the concentration; i) compare the rate of water lost in the network with zero; and j) indicate a leakage state if the rate of water lost in the network is significantly greater than zero.

2. The method as claimed in claim 1, wherein the liquid for temperature control is further removed as steam.

3. The method as claimed in claim 1, wherein the rate in steps (a), (c) and (d) is a weight per unit of time.

4. The method as claimed in claim 1, wherein the measurement in steps (a), (c) and (d) is by means of flow meters.

5. The method as claimed in claim 1, wherein the measurement in step (b) is made by an analyzer.

6. The method as claimed in claim 1, wherein the determinations in steps (e) and (g) are made by a computer.

7. The method as claimed in claim 1, wherein the boiler is a boiler for recovering black liquor.

8. The method as claimed in claim 1, wherein the chemical tracer is a transition metal compound.

9. The method as claimed in claim 8, wherein the chemical tracer is a compound that contains molybdenum.

10. The method as claimed in claim 9, wherein the chemical tracer is a molybdenum salt.

The method as claimed in claim 10, wherein the chemical tracer is sodium molybdate.

12. The method as claimed in claim 1, wherein the chemical tracer is a chemical substance that contains lithium or phosphate.

13. The method as claimed in claim 1, wherein the rate of water lost in the network is determined according to the formula: LK = ChFd - BD - b * d (FW) - * ddn (Ch)) Ch dt dt where: LK = rate of water lost in the network a = dependent variable of the boiler Ch = concentration of the chemical tracer ChFd = Chemical tracer feed speed BD = velocity of the purged water b = variable dependent on the boiler t = time FW = feed water inlet speed; Y M = water mass of the boiler

14. The method as claimed in claim 13, wherein the dependent variable of the boiler, a, is obtained according to the formula: a = BD * Ch ChFd where: BD = speed of purged water Ch = chemical tracer concentration ChFd = chemical tracer feed rate

15. The method as claimed in claim 13, wherein the relationship between M and FW is obtained according to the formula: dM = b * d_FW) dt dt where M is the mass of water in the containment medium; It is time; and FW is the input velocity of the feed water where: b is calculated using a least squares fit of the boiler's historical data.

16. The method as claimed in claim 1, wherein the change calculated in step (g) is obtained using double filtering.

17. The method as claimed in claim 1 further comprises physically analyzing the boiler in response to a positive difference between the rate of water lost in the network and zero.

18. A system for detecting a leak in a boiler in which a liquid for temperature control in a containment medium is supplemented with feedwater and eliminated as purged water, consisting of: the measuring medium in communication with the medium of addition of the chemical tracer; the means of determination of the concentration in communication with the liquid for temperature control; the measuring means in communication with the medium of the purged water; the measuring means in communication with the supply water supplementation means; the bypass means in communication with the addition means of the feed water to derive the change in the rate of the feed water with respect to time; the means of derivation of the mass to determine the mass of the liquid for temperature control; the derivation means in communication with the concentration means of the chemical tracker-to derive the change of concentration with respect to time; the means of derivation of the rate of water that the network loses in communication with the addition means of the chemical tracker, the means of determination of the concentration, the means for measuring the purged water, the means for derivation of the change of the Feeding water rate, mass derivatizing means and derivatization means of the concentration of the chemical tracer; and the means of comparison in communication with the means of determining the rate of water lost in the network to compare with zero.

19. The system as claimed in claim 18, wherein the addition means comprises a tracer source coupled with a flow measuring apparatus and a supply line. The system as claimed in claim 18, wherein the means for determining the mass comprises the processing means coupled with the means for measuring the complementation and elimination. The system as claimed in claim 18, wherein the means of determining the rate of water lost in the network comprises the processing medium coupled with the means of measuring the rate of complementation and elimination, the medium of addition of the tracker and the means for determining the mass.