RU83621U1 - TEMPERATURE INSERT FOR CONTROL OF TEMPERATURE MODE OF BOILER SCREEN PIPES - Google Patents

Abstract

Temperature insert for monitoring the temperature regime of boiler screen tubes, including a pipe with longitudinal fins, a thermocouple, on which a material with a high coefficient of thermal conductivity is applied, characterized in that it contains at least two thermocouples laid in a groove on the frontal surface of the pipe, the ends of thermocouples have access to the rear surface of the pipe through the transverse holes in the fins; above the thermocouples, a material with a high coefficient of thermal conductivity, which is a silver solder, is laid on the rear along the surfaces of the thermocouple pipe are closed with a metal plate, a protective pipe is welded to the plate for supplying thermocouples to the terminal block, a boss (like a metal cup) is installed between the pipe and the plate, in which a third thermocouple is installed.

Description

The utility model relates to the field of power engineering and can be used to measure the temperature of metal pipes of heating surfaces, mainly pipes of furnace screens of energy steam boilers.

The growth of deposits on the inner surface of the boilers is continuously monitored by measuring the temperature of the metal on the pipe wall. For its measurement, special temperature inserts equipped with thermocouples are installed in the screen tubes. The design of the inserts is determined by the type of screen heating surfaces (screens of drum boilers, screens of gas-tight boiler units).

A device for measuring the temperature of metal pipes of furnace screens is made of the same pipes as furnace screens, with longitudinal holes for installing thermocouples and a transverse annular groove for outputting them to the unheated side with a protective thin-walled ring on the outside, welded with a continuous seam to the pipe (D .N. Kemmelman et al., “Adjustment of boiler units.” Reference, M, Energy, 1976, p. 98 fig. 4.1, p. 100, fig. 4.2).

A disadvantage of the known device is that the longitudinal holes and the annular groove in the pipe body weaken the pipe and shorten its service life. In addition, due to greater illumination and poorer heat dissipation, the protective ring undergoes accelerated scale formation compared to the pipe, which will lead to the destruction of the ring, a decrease in the strength of the pipe in the annular section and premature burning of thermocouples. In gas-tight boilers, welding to the pipe a ring that changes the geometric dimensions of the pipe leads to the formation of a local center of slagging. Along with these shortcomings, welding of a thin-walled ring is a very complex technological operation.

The closest known device is "DEVICE FOR MEASURING TEMPERATURE OF METAL OF STEAM BOILER PIPES" (RF patent 19163, IPC No. 7 G01K, 7/02, op. 2001.08.10, prototype). The known device includes a pipe with a longitudinal fin, in the wall of which a hole is made, a thermocouple is installed in it, one end of which has an outlet to the outer surface of the pipe, and the other end to the longitudinal groove of the fin. A wire made of a material with a high coefficient of thermal conductivity, for example, of red copper, snug against the walls of the groove is laid over the thermocouple.

A disadvantage of the known device adopted for the prototype is that the pipes can have technological defects in ellipse and wall thickness, sometimes exceeding the permissible ones, and after grooving the annular groove of a strictly specified size, their stock

strength becomes less than the permissible value. At the same time, reducing the cross section of the annular groove to ensure strength is unacceptable due to the inability to lay the thermocouple in the groove.

The claimed solution allows to increase the reliability and strength of the device, without compromising the reliability of the measurement results and without resorting to the manufacture of devices from turned parts, including with a thickened wall.

This is achieved due to the fact that the temperature insert for controlling the temperature conditions of the boiler screen tubes, including a pipe with longitudinal fins, a thermocouple on which a material with a high coefficient of thermal conductivity is applied, according to a utility model, contains at least two thermocouples laid in a groove on the frontal surface of the pipe, the ends of the thermocouples have access to the rear surface of the pipe through the transverse holes in the fins, a material with a high thermal conductivity coefficient is laid over the thermocouples, representing oboj silver solder on the rear surface of the thermocouple tube closed metal plate, is welded to the attachment protective tube for thermocouples supply to the terminal block between the tube and the lug plate set (such as metallic glasses), which is installed in a third thermocouple.

A feature of the proposed utility model is that in a temperature insert for controlling the temperature conditions of boiler screen tubes, a small-section cable thermocouple in a metal sheath with a diameter of 1.5 mm is laid in a groove pressed by means of a hydraulic press on the frontal generatrix of the screen tube, followed by its melting with silver solder. To increase the reliability of the temperature insert, two thermocouples are installed on the frontal generatrix, one of which is a backup. A third thermocouple is installed in the boss on the rear generatrix (or soldered with silver solder).

The advantage of this insert in relation to known inserts is the minimum narrowing of the internal section, allowing ball cleaning of the inner surface of the pipe; preservation of pipe strength.

The advantages of the utility model include:

- good adhesion of silver solder to steel;

- high thermal conductivity of silver, providing speed and high accuracy of temperature measurements;

- fusion with silver does not damage the thermocouple, as the melting point of the solder is below the maximum operating temperature of the thermocouple;

- high manufacturability of the insert, not requiring processing

surface after melting;

- the geometric dimensions of the outer surface of the pipe are saved, which prevents the possibility of the appearance of local centers of slagging;

- the durability of the model.

Figure 1 - temperature insert for monitoring the temperature of the screen tubes of the boilers, section, General view; figure 2 is the same, a section along the cross-section aa in figure 1.

The temperature insert for controlling the temperature of the screen tubes of the boilers includes a pipe - 1; fin - 2; frontal generatrix - 3; groove - 4; thermocouple - 5; rear generatrix - 6; silver solder - 7; overlay - 8; protective pipe - 9; the boss - 10.

A useful model of the temperature insert for gas-tight boilers operating on supercritical parameters is proposed. The heating surface of the boiler consists of sections of the fin pipes 1. The surface of the pipe 1 facing the boiler furnace is the frontal generatrix 3, the opposite side is the rear generatrix 6. On the frontal generatrix surface 3 of the pipe, a groove 4 is pressed by a press, into which two thermocouples are placed 5. Thermocouples 5 pass to the rear generatrix 6 through drilling in the fins. Then the thermocouples 5 in the groove 3 are fused with silver solder 7 until the geometric dimensions of the pipe are restored. On the rear generatrix of the pipe 6, the thermocouples 5 are closed with a metal plate 8, a protective pipe 9 is welded to the plate 8 to supply the thermocouples 5 to the terminal block. Between the pipe 1 and the lining 8 there is a boss 10 (like a metal cup), in which a third thermocouple 5 is installed.

The device operates as follows.

The flue gases heat the pipe 1. As a result of heating the pipe 1 with "hot" junctions of thermocouples 5, fixed in the annular groove 4, thermopower appears in thermocouples 5 When connected to the terminal block of the measuring device, the temperature of the metal on the frontal and rear generatrices of pipe 1 is determined. Based on the temperature difference between the frontal and rear generatrices, one can judge the state of the surface of the pipe (clean or slagged).

Silver solder 7, covering thermocouples 5, having high heat resistance and corrosion resistance to flue gases, on the one hand, protects the conductors from their effects, on the other hand, having constant tight contact with the surface of the groove, helps to remove heat from the pipe, thereby reducing temperature of conductors and insulation of thermocouples, which leads to an increase in the durability of thermocouples 5.

Claims (1)

Temperature insert for monitoring the temperature regime of boiler screen tubes, including a pipe with longitudinal fins, a thermocouple, on which a material with a high coefficient of thermal conductivity is applied, characterized in that it contains at least two thermocouples laid in a groove on the frontal surface of the pipe, the ends of thermocouples have access to the rear surface of the pipe through the transverse holes in the fins; above the thermocouples, a material with a high coefficient of thermal conductivity, which is a silver solder, is laid on the rear along the surfaces of the thermocouple pipe are covered with a metal plate, a protective pipe is welded to the plate for supplying thermocouples to the terminal block, a boss (such as a metal cup) is installed between the pipe and the plate, in which a third thermocouple is installed.