RU2214559C1 - Drum boiler-operation method - Google Patents

Abstract

FIELD: steam generation, possibly in heat and electric power stations and boiler aggregates. SUBSTANCE: method comprises steps of generating steam in several stages of boiler water evaporation; performing continuous blowing from last stage of boiler water evaporation; controlling flowrate of blowing water according to salt content of boiler water of first evaporation stage. EFFECT: enhanced operational reliability and effectiveness of drum boiler. 1 dwg

Description

 The invention relates to the field of power engineering and can be used in thermal power plants and boiler plants.

 A well-known analogue is the method of operation of a drum boiler (see Delyagin G.N., Lebedev V.I., Permyakov B.A. Heat-generating installations: Textbook for high schools. M .: Stroyizdat, 1986. P. 358), according to which steam get in several stages of boiler water evaporation, continuous purging is carried out from the last stage of boiler water evaporation. This analogue is taken as a prototype.

 The reason that impedes the achievement of the technical result indicated below when using the known method adopted for the prototype is that in the known method of operation of the drum boiler, the amount of purge water removed from the last stage of evaporation is constant, that is, does not depend on the quality of the boiler water, which during operation of the boiler may vary. The steam generated in the last stage of boiler water evaporation by an external cyclone is sent to the separation-active part of the first stage of evaporation. It is known that external cyclones with an internal cochlea often produce steam of high humidity, sometimes reaching up to several percent (in some cases, up to ten percent), that is, intensive removal of boiler water (drip entrainment) or transfer of boiler water from the latter occurs from the external cyclone - the second stage of evaporation in the first, which leads to an increase in the salt content of boiler water in the first stage of evaporation. In addition, with an increased salt content of feed water, an increase in the salt content of boiler water in the first stage of evaporation and, as a result, an increase in the salt content of saturated steam of this stage of evaporation also occur in the first place. Considering that the steam production of the first stage of evaporation is significantly higher than the steam capacity of an external cyclone, with a significant increase in the salt content of the boiler water in the first stage of evaporation, there will be a noticeable deviation in the quality of the saturated steam generated by the boiler from normalized. An increase in the salt content of saturated steam leads to an intensive deposition of scale on the inner surface of the pipes of the superheater and heat exchangers. In addition, the excess salt content of the boiler water moving along the circulating circuits of the drum boiler from a predetermined value set by the project leads to an acceleration of the formation of deposits on the inner heating surfaces of the drum boiler, disruption of its normal operation and to intensive corrosion processes that can occur in a relatively short time disable equipment, which reduces the reliability of the drum boiler. In addition, when the salinity of the boiler water is below the standard value, the removal of a constant amount of purge water leads to an increase in the loss of the mass of boiler water and the heat contained in it, which reduces the efficiency of the drum boiler.

 The technical result of the claimed solution is to increase the reliability and efficiency of the drum boiler.

 The invention consists in the following.

 To increase the reliability and efficiency of the drum boiler operation, it is advisable to automatically control the purge water flow according to the salinity of the boiler water of the first evaporation stage.

 The specified technical result in the implementation of the invention is achieved by the fact that in the known method of operation of a drum boiler, steam is obtained in several stages of boiler water evaporation, continuous purging is carried out from the last stage of boiler water evaporation. The peculiarity lies in the fact that the flow of purge water is regulated by the salinity of the boiler water of the first stage of evaporation.

 The drawing shows a diagram of a drum boiler that implements the proposed method.

 The drum boiler contains the first stage of boiler water evaporation - drum 1, the second (last) stage of boiler water evaporation, made in the form of an external cyclone 2, feed water pipe 3, regulating body 4 of feed water flow installed on pipe 3, purge water pipe 5, a purge water flow regulator 6 connected to a sensor 7 of the boiler water salinity of the first evaporation stage and a purge water flow regulator 8 installed on the pipeline 5.

 The method is implemented as follows.

 Feed water is supplied through pipeline 3 to the first stage of boiler water evaporation — drum 1. Continuous purging of the boiler is carried out from the last stage of boiler water evaporation of the external cyclone 2 through purge water pipe 5. The sensor 7 measure the salinity of the boiler water in the first stage of evaporation. The signal from the sensor 7 is continuously fed to the input of the purge water flow controller 6, the output of which is connected to the regulating body 8 of the purge water flow. If during operation of the drum boiler, the salt content of the boiler water of the first evaporation stage exceeds a predetermined value, a signal is generated by the regulator 6 to increase the purge water flow by a signal from the sensor 7 of the boiler water content of the first evaporation stage. The command signal generated by the regulator 6 acts on the regulatory body 8, which increase the flow rate of purge water. By increasing the flow rate of purge water, the salt content of boiler water in the first stage of evaporation is reduced to a predetermined value that ensures the safe operation of the drum boiler. If, during the operation of the drum boiler, the salt content of the boiler water of the first evaporation stage is lower than the set value, the automatic control system reduces the flow rate of the purge water. By reducing the flow rate of purge water, the mass loss of the boiler water and the heat contained therein are reduced.

 The boiler water level in the drum 1, at which the normal operation of the drum boiler is ensured, is maintained by changing the flow of feed water by the regulating body 4 installed on the pipeline 3.

 Thus, by changing the flow rate of the purge water, the salt content of the boiler water in the first stage of evaporation is maintained at a predetermined level, which generally increases the reliability and efficiency of the drum boiler.

Claims (1)

 The method of operation of the drum boiler, in which steam is obtained in several stages of boiler water evaporation, continuous purging is carried out from the last stage of boiler water evaporation, characterized in that the purge water flow is controlled by the salinity of the boiler water of the first stage of evaporation.