SU787779A1 - Apparatus for protecting high-pressure preheater from level increasing - Google Patents

Description

(54) DEVICE FOR PROTECTING HEATER OF HIGH PRESSURE AGAINST LEVEL IMPROVEMENT

one

The invention relates to a power system and can be used in the protection systems of steam turbines.

A device for protecting a high pressure preheater against level increase is known, which contains a fast-acting valve installed in the feedwater supply line for control purposes, a pressure differential sensor, one input of which is connected to the preheater volume filled with condensate and the other through an equalizing vessel with a steam volume , instrumentation devices, the first of which is equipped with a normally open contact included in the control circuit, and is connected to a differential pressure sensor, and the second has its own sensor and normally open contact 1 ..

A disadvantage of the known device is the frequent false alarms caused by the boiling up of hot condensate accumulated in the preheater with deep and rapid changes in vapor pressure. The resulting steam rushes into the turbine, which generates a significant differential pressure over the height of the preheater in the absence of a real increase in the level of condensate.

The purpose of the invention is to increase reliability by eliminating false positives with a deep change in vapor pressure. The goal is achieved by the fact that a normally closed second instrument-detector is also connected to the control circuit of a high-speed valve in series with a normally open contact, and the sensor of this instrument-detector as well as the first is made as a differential pressure sensor with its own

10 by a leveling vessel connected to another height point of the steam volume of the heater, and the second input of this sensor is connected to the leveling vessel of the sensor of the first instrument-detector. The drawing shows a schematic of a device for protecting a high pressure preheater against a rising level.

Claims (2)

The device contains a quick-acting valve 2 with a control circuit 3 installed in the feedwater supply line 1, a pressure differential sensor 4, one input 5 of which is connected to the volume 6 of the heater 7 filled with condensate, and the other input 8 through leveling vessel 9 to the steam volume 10 of the heater 7, the devices And signaling devices and 12, the first And of which is equipped with a normally open contact 13, included in the control circuit 3, and is connected to the sensor 4 differential pressure, and the second device, a signaling device 12 has its normally closed contact 14, t It is also connected to the control circuit 3 in series with a normally open contact 13, and its sensor 15, made in the form of a differential pressure sensor with its leveling vessel 16 connected to another height point of the steam volume 10 of the preheater 7, and the second input of the sensor 15 is connected to leveling vessel 9. The control circuit 3 is connected to the power supply 17. The device works as follows. When the preheater overflows (for example, due to pipe rupture), the level in it quickly increases and at the moment when the target value specified for the device-alarm device And closes, contact 13. At the same time, the pressure in the steam volume 10 has not yet changed and the normally closed contact 14, the detector 12 does not change its state. Therefore, the control circuit 3 closes the high-speed valve 2 on line 1 and stops the feed water supply. With a deep disturbance of steam pressure (for example, with a rapid load relief by a turbogenerator) due to the violent boiling up of accumulated condensate, the vapor pressure at the upper and lower sensor connection points changes several times. In this case, the pressure at the lower point will be greater than the pressure at the upper point by the amount of hydrodynamic losses in the reverse steam flow. If the resulting dynamic pressure differential exceeds the value specified for the device-alarm 11, then its contact is closed. But at the same time, a dynamic pressure differential occurs at the sensor 15. When the latter reaches its specified value, the warning device opens its contact 14, which prevents the valve from being falsely closed 2. After equalizing the pressures in the steam volume 10 of the preheater 7, contacts 13 and 14 return to their original position and the device is again ready for operation. Thus, false positives are avoided in this device with a deep change in vapor pressure. Apparatus of the Invention A device for protecting a high-pressure preheater against an increase in level, comprising a quick-acting valve with a control circuit installed in the feedwater supply line, a differential pressure sensor, one input of which is connected to the preheater volume filled with condensate and the other through a leveling vessel with a vapor volume and instrumentation devices, the first of which is a normally open contact connected to the control circuit, and is connected to a differential pressure sensor, and the second has its own sensor and normally closed contact, characterized in that, in order to increase reliability by eliminating false alarms with a deep change in vapor pressure, the normally closed contact of the second instrument-detector is also included in the control circuit of the high-speed valve in series with the normally open contact, and the sensor of this instrument analyzer is also , like the first one, made in the form of a differential pressure sensor with its leveling vessel connected to another height point of the steam volume of the preheater, and The second input of this sensor is connected to the leveling vessel of the sensor of the first device-sigalizer. Sources of information taken into account in the examination 1. Automation of large thermal power plants. Under total ed. M. P. Shalman, M., “Energie, 1974, p. 149-157. h N th V7 sixteen eight {five and / 2