SU945589A1 - Steam turbine feed-water preheater - Google Patents

Description

The invention relates to a power system, in particular to regenerative heaters of steam turbines, and can be used at thermal power plants.

Known regenerative heater of a steam turbine, comprising a housing, inside which is located a water distribution device, a condensate collector and a pipe for supplying steam.

The water distribution device is made in the form of perforated trays, between which passages for steam are provided. The heater itself is separated from the condensate collector by a partition in which water-discharge pipes with check valves and an equalizing pipe are designed to equalize the pressure in the water and steam compartments [Ί].

The disadvantage of this heater is that when the turbine completely relieves the steam load, vol. that is formed during boiling of the water located in the condensate collector, is partially carried out into the flow part of the turbine and increases the dynamic ⁵ speed overspeed.

The purpose of the invention is to increase reliability by preventing the transfer of wet steam into the flow part of the turbine _J0 during load shedding.

This goal is achieved by the fact that at the end of the steam supply pipe a check valve is mounted in the form of a partition with windows, each of which ₁₅ has a rotary shutter with a rotation limiter.

In addition, the partition and the limiter are made in the form of coaxial cylinders.

In FIG. 1 schematically depicts a surface-type regenerative heater, longitudinal section / in FIG. 2 - the same for the mixing heater.

945589 4

A device in the heater body 1 with a condensate collector 2 in the lower part and a pipe 3 for supplying steam, at the end of the latter, a non-return valve is fixed in the form of a partition 5 with 4 windows 5 for the passage of steam. Each of the windows · 5 has a rotary damper 6 mounted on the axis of rotation 8 7- limiter flap 6 is designed as a perforated shield ¹⁰ and mounted parallel to the partition at a distance of less than the height of the damper.

To reduce the loss of steam throttling in the windows 5, the total 15 area of their passage section exceeds the cross-sectional area of the pipe 3, for which the pipe is equipped with a conical part 9 at the end. Inside the housing 1, a water-distributing device 10 in the form of a tube bundle is installed (Fig. 1), or in the form of a pipe with water supplying holes (Fig. 2). The pipe 11 is intended for supplying cold water, the pipe 25 12 - for the removal of heated water, and the pipe 13 - for the removal of condensate heating steam.

In the embodiment of the heater (Fig. 2), the baffle 4 and the limiter 8 are used in the form of coaxial cylinders. The partition 4 is a continuation of the pipe 3. The condensate collector 2 is separated by a horizontal partition 14, dividing the heater into a water ₃₅ and a steam compartment. Pipe 11 serves for supplying cold water, pipe 12 for draining heated water (condensate). The nozzles 15 with non-return valves 16 are designed to pass water from the steam compartment into the water compartment, and the nozzle 17 “to equalize the pressure in the compartments.

The heater operates as follows.

Cold water is supplied into the housing 1 through the pipe 11, which is heated by steam entering the heater from the turbine extraction through the pipe 3 and condensing in the heater body. Heated water is discharged from the heater through the nozzle 12. In the embodiment with a surface heater (Fig. 1), condensation of heating steam accumulates in the condensate collector 2 and is discharged through the nozzle 13. In the embodiment with a mixing heater (Fig. 2), the heated water flows through the nozzles 15 into the condensate collector 2 and from there it is discharged through the pipe 12. In this case, the shutters 6 are open as far as the limiter 9 allows.

When the turbine relieves the load, a sharp (within 1-1.5 s) pressure drop occurs in the turbine, the sampling line and the heater body 1, which leads to explosive boiling up of water in the condensate collector 2. The resulting steam with trapped moisture rushes from the heater into a turbine. However, at this moment, the shutter 6 slams, the movement of the vapor-air mixture towards the turbine is interrupted. This helps to increase the reliability of the turbine installation, since it completely eliminates the influence of the heater on the dynamic casting of rejects and removes all concerns about the possibility of destruction of the blades due to moisture in the return steam stream.

Claims (2)

The invention relates to a power system, in particular to regenerative steam turbine preheaters, and can be used in thermal power plants. A regenerative steam turbine preheater is known, comprising a housing within which a water distribution device, a condensate collector, and a steam supply pipe are located. The water distribution device is made in the form of perforated trays, between which steam passages are provided. The preheater itself is separated from the condensate trap by a partition wall in which water-draining nozzles with check valves and a balancing nozzle, designed to equalize the pressure in the water and steam compartments 1, are placed. The disadvantage of this preheater is that, when the turbine completely discharges the load, the steam generated by the boiling water contained in the condensate collector is partially carried into the flow part of the turbine and increases the dynamic overrun. The purpose of the invention is to increase reliability by preventing the removal of wet steam to the flow part of the turbine during load shedding. The goal is achieved by the fact that at the end of the steam supply pipe there is a non-return valve fixed in the form of a partition with windows, each of which has a butterfly valve with a rotation stop. In addition, the partition and the limiter are made in the form of coaxial cylinder. In FIG. 1 shows schematically a regenerative surface-type heater, a longitudinal section; FIG. 2 - the same for the mixing preheater. The device in the preheater housing 1 with a condensate collector 2 in the lower part and a nozzle 3 for supplying steam, at the end of the latter, a non-return valve fixed in the form of a partition 4 with windows 5 for the passage of steam. Each of the windows 5 has a rotary damper 6 fixed on the axis 7. The limiter 8 of the rotation of the dampers 6 is designed as a perforated shield and is installed parallel to the partition at a distance smaller than the height of the damper. To reduce the steam throttling loss in the windows 5, the total placer of their flow area exceeds the cross-sectional area of the nozzle 3 for which the nozzle is provided with a conical part 9 at the end. Inside the housing 1 there is a water distribution device 10 in the form of a tube bundle (Fig. 1), or in the form of a pipe with water inlets (Fig. 2). The pipe 11 is designed to supply cold water, the pipe 12 - to drain the heated water, and the pipe 13 - to drain the condensate gray and its steam. In the embodiment of the preheater (Fig. 2), the partition 4 and the stop 8 are made in the form of coaxial cylinders. The partition t is a continuation of the pipe 3. The condensate trap 2 is separated by a horizontal partition dividing the preheater into a water and steam compartment. The nozzle (41) serves to supply cold water, the nozzle (12) serves to drain heated water (condensate). The pipes 15 with check valves 16 are designed to pass water from the steam compartment to the water, and the pipe 17 to equalize the pressure in the compartments. The heater works as follows. Cold water is supplied to housing 1 through pipe 11, which is heated by steam entering the preheater from a turbine takeoff through pipe 3 and condensing in the heater body. The heated water is discharged from the preheater through pipe 12. In the version with a surface heater (Fig. 1), the condensate of baptized steam accumulates in the condensate collector 2 and four 94 cutoff pipes 13 are discharged. 2 and from there is discharged through nozzle 12. At the same time, the valves 6 are open as far as the limiter 9 allows. When the turbine is relieved of the load, there is a sharp (within 1-1.5 s) pressure drop in the turbine, the extraction line and the housing 1 under heater, which leads to the violent explosive boiling of water in the condensate collector 2. The resulting vapor with trapped moisture rushes from the preheater to the turbine. However, at this moment the shutters 6 are shut, the movement of the vapor mixture of the ear mixture towards the turbine is interrupted. This contributes to an increase in the reliability of the turbo installation, since it completely eliminates the effect of the preheater on the dynamic casting of selections and removes all fears about the possibility of destruction of the blades due to the presence of moisture in the reverse steam flow. 1. Regenerative steam turbine preheater comprising a housing within which a water distribution device, a condensate collector and a steam supply nozzle are located, characterized in that, in order to increase reliability by preventing wet steam from being discharged into the flow section of the turbine during load shedding, at the end the steam supply pipe is reinforced with a check valve in the form of a partition with windows, each of which has a butterfly valve with a turn limiter. 2. Regenerative heater POP.1, characterized in that the partition and the restrictor is made in the form of coaxial cylinders. Sources of information taken into account in the examination 1. USSR author's certificate, Cl. F 22 D 1/32, 1971.