UA49961C2 - Method for detecting water leaks in boiler tubes - Google Patents

Abstract

The present invention relates to the measurement technology and can be used for monitoring water leaks in boiler tubes of heat recovery apparatuses. The proposed method for detecting water leaks in boiler tubes consists in measuring, by two temperature transducers, a temperature difference in the monitored medium which temperature and heat capacity shall change as the result of steam generation when the boiler tube leaks through. Due to different heat capacity of the transducer housings, the transducers react with different speed to the temperature changes. The instant of water leak is determined from the increase of the slope of the characteristic defining the change of the monitored medium temperature difference as a function of time. The said characteristic slope, which depends on the presence of steam in the monitored medium, is preliminarily determined.

Description

Description of the invention

The method refers to measuring equipment, and can be used to control water leaks in 2 pipes of boilers-utilizers, installed in thermal technological devices for the utilization of heat of chemical reactions, where the heat carrier is a medium with a low heat capacity, for example, gas or a mixture of gases.

There are well-known thermoconvective analyzers of the quality of substance flows (see Obnovlenskyi P.A., Sokolov G.A. Teplovye sistem! control parameters of processes of chemical technology. L.: Khimiya. 1982. 176bs.s.91), the principle of operation of which consists in comparing signals two thermosensors (resistance thermometers or thermocouples), one of which measures the temperature of the medium under study, and the second - the temperature of the heater, which depends on how much heat was taken from it by the medium, the consumption of which is stabilized, and the heat capacity depends on the concentration of one substance in another.

There are well-known thermoconvective flow meters (see the same source) of various designs, the principle of operation of which is similar, but the quality of the medium is unchanged, and its flow rate changes, which depends on the heat removal from the 12 heater.

The disadvantage of these measurement methods is the presence of heaters or refrigerators in the designs of devices made on the basis of these methods, due to which the design is dramatically complicated, and the cost of the devices increases by two or more times.

The invention is based on the task of creating a method of determining the moment of appearance of water leaks in boiler pipes, which would allow creating simple in design, easy to maintain and cheap control devices.

The task is solved by using thermosensors, whose protective casings are made of materials that react to temperature changes at different speeds due to the different thermal conductivity of these materials, and the moment of boiler water passage is determined by increasing the steepness of the graph of the change in the temperature difference of the medium over time, measured by thermosensors. the steepness of which depends on the appearance of water vapor in the environment and is known in advance. Gee)

Fig. 1 shows examples of devices for determining the moment of appearance of boiler water leaks, made on the basis of the proposed method. Figure 2 shows a longitudinal section of a ceramic protective casing with low thermal conductivity, made using a special technology. Figure 3 shows a longitudinal section of a metal protective casing with high thermal conductivity. The method of installation of casings in the boiler body does not have (77 values. Ge)

In furnace 1 (see Fig. 1), for example, in a sulfuric acid workshop, liquid sulfur and air for its combustion flowing at a temperature of 1100O0degrees are supplied in two streams. The product of combustion - gas ЗО »5 (hereinafter referred to as gas) passes successively through the boiler tubes 2 and the tubes of the superheater Z, where it leaves part of its heat, and F3 enters the contact apparatus (not shown in Fig. 1), where the catalyst from oxides vanadium burns up to 5053 and, in the next 3 hours, enters the acid compartment for absorption (not shown in Fig. 1). In order to achieve a low resistance to the gas flow and a large contact area of vanadium oxides with the gas, the catalyst is made in the form of granules. When boiler tubes 2 or superheater C tubes pass water or steam, for example, due to corrosion, it partially reacts with the gas, and at the same time, sulfuric acid vapor is formed, which, falling on the catalyst granules, destroys them. The catalyst is covered with a hard, dense shell, which turns into dust when C 50 breaks down. At the same time, the gas flow resistance increases, and accordingly, the productivity of the shop decreases. In the production of sulfuric acid, a large amount of catalyst is used, and it has a high cost.

Iz» Catalyst recovery technology requires a lot of energy and labor. In order to save the catalyst, it is necessary to detect water and steam leaks in the boiler pipes 2 and superheater pipes C in a timely manner and stop the gas flow by extinguishing the flame in furnace 1. You can restart furnace 1 only after carrying out repair work. shk The mode of operation of the boiler (not shown in Fig. 1) is such that the boiler tubes 2 remove the same amount of heat (se) regardless of the gas temperature. Therefore, before and after the boiler tubes 2, thermal sensors (for example, thermocouples with XA graduation) 4 and 5 are built into the walls of the furnace 1 and connected to a potentiometer 6 (for example, about the type KSP - Z or KSP - 4, which are functionally capable of recording a graph temperature changes) on the contrary, that is, in

Gee! 20 points "a" are connected to the minus terminals of the thermocouples, and the positive terminals are connected to the potentiometer b. The terminal "y" of the thermocouple 4 is connected to the terminal "y" of the potentiometer b, and to the terminal "y" of the potentiometer b of the terminal y" of the thermocouple 5 . and Thermocouple 4 is in a higher temperature zone than thermocouple 5 and is built into a ceramic protective casing (see fig. 2). And thermocouple 5 is embedded in a metal protective casing (see fig. 3) made of corrosion- and temperature-resistant steel, for example, grade ХНЗ2Т. The pipe 10 (see Fig. 33) is blocked on one side 29 by a cover 11. To increase the reaction speed of the thermocouple (not shown in Fig. 3) to a change in gas temperature and

GF) to give the protective cover the properties of a radiator, rings 12 are welded along the pipe 10 at certain intervals, made of the same steel as the pipe 10, and the cover 11. Plates 13 are also welded to the cover 11 for the same purpose. o For comparison, we present the values of the specific heat capacity of water vapor and gas 5O 5 at different temperatures in Table 1 (see Reference book of sulfuric acid. 2nd ed. Ed. Ph.D., Prof. Malyna K.M. M. : Chemistry, 1971. 60 74ds., pp. 26, 27, 72). b5 BO 0.5092 0193

1000 0.5929 0.207 1100 0.6о80 0.208

As can be seen from Table 1, the heat capacity of water vapor at various temperatures is approximately three times greater than that of ZO gas."

Therefore, when the boiler pipes 2 (Fig. 1) flow, not only the temperature of the gas will change, but also its ability to take heat from the thermocouple 5. This difference will be shown by the potentiometer 6. The previous temperature changes at 70 potentiometer 6 will appear on the graph (on not shown in the drawings), as a slight drift in one direction or another, and when boiler pipes 2 leak, the steepness graph will change dramatically.

By passing steam through the pipes of the superheater C, its temperature is regulated. Therefore, the change in gas temperature after the pipes of superheater C occurs frequently and in a wide range. In addition, the change in gas temperature can be affected by the flow of boiler pipes 2. Therefore, it is possible to install thermocouples 7 and 8 next to each other, at one point, after the pipes of superheater C, while one of them is installed in a ceramic protective casing (see Fig. 2 ), and the second - in a metal one (see Fig. 3). Thermocouples 7 and 8 are connected to potentiometer 9 in the same way as in the previous case.

Potentiometer b should have a scale, the maximum of which corresponds to the difference in gas temperatures before and after the boiler pipes 2. Potentiometer 9 should have a maximum of the scale by the value by which the gas temperature can change in or.

When the pipes of the superheater 3 are leaking, the thermocouple 8 will react to the temperature change faster than the thermocouple 7, and a "jump" will appear on the graph of the potentiometer 9, which will level off again after a certain time, but its appearance will be an indication of the pipes of the superheater 3 leaking.

Similarly, as after the pipes of the superheater 3, it is possible to install thermocouples 4 and 5 after the pipes of the boiler 2, but then it will not be possible to observe the drop in gas temperature on the pipes of the boiler 2.

Claims (1)

The formula of the invention is a method of determining the moment of water leakage in boiler pipes by measuring the temperature difference with two thermosensors in the medium, the heat capacity and temperature of which change due to the appearance of water vapor in it at the moment of the flow of boiler tubes, which differs in that the thermosensors are used, the protective covers of which are made of materials that react to temperature changes at different speeds due to the different thermal conductivity of these materials, and the moment of boiler water transmission is determined by (o) the increase in the steepness of the graph of the change in the temperature difference of the medium over time, measured by thermosensors, the steepness of which depends on the appearance in the medium of water vapor and is known in advance. - and? sh» se) se) (o) - ime) 60 b5