SU1116191A1 - Method of steam power plant operation - Google Patents

Abstract

METHOD OF OPERATION OF THE VAPOR-POWER PLANT by adjusting the steam flow rate to the turbine, condensing steam in a condenser by supplying cooling water from the cooling tower through the discharge piping and tapping it through the circulation pump through the discharge pipelines to the cooling tower sectors while adjusting SC COJ03ftAf A-im-m-. cooling water, supplying a condensate through a condensate pump to regenerative heaters and make-up water to a condenser, which, in order to improve maneuverability, reliability and efficiency during negative air temperatures, when reaching at least one sector cooling water temperatures 13–15 ° C mix cooling water from the discharge pipe after the circulation pump into the pressure pipeline, increase the flow rate of the make-up water and condensate for recirculation, and at the beginning of a decrease in temperature - cooling (L of the supply water from the initial one, increases the supply of cooling water to the discharge pipeline, reduces the flow of make-up water, and turns off the recirculation of the condensate.

Description

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The invention relates to heat and power engineering and can be used at thermal power plants (TPPs) with Ge.1lera-Forgo dry cooling towers with significant daily and annual changes in air temperature.

A method of operating a steam power plant by controlling steam flow to a turbine and condensing steam in a condenser of cooling water from a cooling tower through pressure pipelines and its outlets through a circulation pump through discharge pipelines to the sectors of the cooling tower while regulating cooling water temperature is fed through a condensate pump with recirculation. condensate fit regenerative heaters and make-up water to condenser C 1

The well-known method of operation of a steam power plant is characterized by insufficient maneuverability when attracting a plant to control the load in the power system, reducing reliability and efficiency when working with reduced loads and at negative temperatures of air supplied to the cooling tower. The greatest dependence of reliability and efficiency on air temperature occurs for TPPs operating in conditions of high mountains, for which are characterized by large differences in air temperature during the day and at night, and thaws in summer and winter.

These features are delivered to maintain elevated cooling water temperature at the outlet of the cooling tower sectors in order to prevent freezing of individual tubes of columns of tori. The presence of a significant number of tubes leads to large temperature sweeps across the width of the column, which increases with increasing wind speed and decreasing air temperature, which further increases the average temperature of the cooling water, increasing the pressure in the condenser and reducing the efficiency of the turbine. A decrease in heat removal from the cooling tower is provided by increasing the flow rate of cooling water through the sectors, covering the louver to reduce air flow, and at low air temperatures the load of the turbine cannot be reduced without additional heat loss from the condenser besides the turbine.

The purpose of the invention is to improve the maneuverability, reliability and efficiency of the operation of the steam power plant during the period of negative air temperatures.

This goal is achieved in that according to the method of operation of a steam power plant by controlling the steam flow rate to the turbine, condensing steam in a condenser by cooling water from the cooling tower through pressure pipelines and tapping it through the circulation pump through the discharge pipelines to the cooling sectors when regulating the cooling water temperature, flow through a condensate pump with recirculation of condensate to regenerative heaters and make-up water to the condenser, when at least one Cooling water temperature 13-15 C mixes cooling water from the discharge pipe after the circulation pump into the discharge pipeline, increases the flow rate of the make-up water and condensate for recirculation, and at the beginning of the decrease in the cooling water temperature from the initial one, reduce the flow of make-up water and turn off the recirculation of condensate. The drawing shows a schematic diagram of a steam power plant for carrying out the method.

The steam-powered unit contains a boiler I, connected to the turbine 2, a condenser 3, which by pressure and discharge pipes 4 and 5 is connected to annular collectors 6 and 7, to which the sector (cooling column) 8 is connected with the air vent 9.

Ring collectors 6 and 7 of the cooling tower (part of the cooling tower is shown, i.e. one of its sectors) are interconnected by jumpers 10 and 1 with shorting valves 12 and 13. The pressure and discharge pipes 4 and 5 are interconnected by jumpers 14 and 15 shut-off and control valves 16, 17 and fitted with valves 18 and 19. A drain line 21 of the main condensate to which the regenerative heaters 22 and the condensate pump 23 are installed is connected to the discharge pipeline 5 after the circulation pump 20 with recirculation line 24. Tank 25 is connected to sector 8. Valves 16 and 17 are equipped with actuators 26 with actuators.

27. The installation is equipped with control valves 28, valves 29, sensors 30 and 31 of temperature and pressure, connected through controller 32 to the actuators .27. The make-up line 33 is connected to the condenser 3, and the sector 8 is provided with louvers 34. The generator 35 has an electrical load sensor 36 associated with the actuator 27 of the turbine-regulating valves 28 2. A tank 25 connected to the sector 8 is connected by pipelines 37 and 38, on which valves 29 are installed, with pipelines 39 and 40 of sector 8.

The method of operation of the steam power plant is as follows.

Steam from boiler 1 is supplied to turbine 2, generator 35 generates electricity, and steam from turbine 2 is supplied to condenser 3, where it is cooled and condensed by cooling water from discharge pipe 4. Coolant water is mixed with condensate of exhaust steam and part of it is fed to circulation pumps 20 through the discharge pipe 5 into the annular collector 7, from where it enters the sector 8, is cooled by air and fed through the pressure pipe 4 to the condenser 3. Another part of the condensate is a condensate pump 23 through line 21 of the main condensate Sat is supplied to regenerative heaters 22, where it is heated with steam from turbine 2 and enters boiler 1. Depending on the electrical load (steam consumption) | and also on the ambient air temperature (water temperature at an inlet from sector 8 via sensor 30), the cooling temperature water is maintained within acceptable limits by covering (opening) the louver 34. This is necessary to avoid freezing the tubes of the columns of sector 8. When unloading the installation to the technical minimum, less cooling water and even more digging blinds, which is not economically feasible.

Therefore, when the installation is unloaded below 0.7 from the nominal electric load or when the cooling water temperature approaches 13–15 s, the sensor 30 pulls the cooling water temperature to 35–40 ° C by covering (closing) the louver 34 or turning off several sectors 8, opening

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The discharge valves 12, 13 and the installation are unloaded.

A signal is sent to the controller 32, which commands the actuators 27 of the shut-off and control valves 16,17 and the valves 18 and 19. This opens the shut-off and control valves 16 and 17, and the valves 18 and 19 are closed. Water from the discharge pipe 5 after the circulation pump 20 through the bridge 14 is mixed with the water of the pressure pipe 4 to the valve 18, and after the valve 19 with the bridge 15 through the water of the pressure pipe 4 between the condenser 3 and the valve 18. The degree of opening (closing) of the valves 18.19 and shut-off and control valves 16,17 ybiraets .iskhod of flow resistance conduit 4 and 5, nepei aii4eK 14 and 15, the annular collectors 6,7 and 8 sectors, i.e. cooling water circuits. At the same time, the valve 29 in the pipe 38 is opened, which provides additional circulation of water through sector 8 and the flow of make-up water through line 33 increases to maintain the level in the condenser 3, and the value equal to the indicated increase in the flow of sub-water is discharged into tank 23. the presence of circulation through sectors 8 according to indications of temperature sensors 30. With an increased water pressure Bbmie nominal to sensor 31 in the discharge pipe 5, after the circulation pump 20, the valve (recirculation valve) 29 opens and the flow of condensate through the recirculation line 24 to the condenser increases. Then increase the flow of cooling water from the discharge pipe 5 at jumper 14 and, respectively, at jumper 15 at the beginning of the cooling water temperature decrease from the initial (35-40 C) is proportional to the steam consumption per turbine. This is provided by applying a signal from the temperature sensor 30 to the regulator 32, the pulse of which affects the corresponding opening of the shut-off valve. tours 16 and 17 and closures of the valves 18 and 19. When a stable circulation of water through the circuit is reached: discharge pipe 5, jumper 14, pressure pipeline 4, ring collector 6, sector 8, ring collector 7, discharge pipe 5, jumper 15, a HanopHbiii duct 4, a condenser 3, a circulation pump 20, shuts off the recirculation of the condensate pump 23 and opens the louver 34 to lower the temperature of the cooling water. Gate valves 18 and 19 can be fully closed, and the shut-off and control valves 16 and 17 are fully open. If necessary, valves 18, 19 can be undermined (in the stereo mode). Shut-off valves 12, 13 are closed, the supply of water to tank 25 is interrupted, and the cooling water circuit can be fed from it. Thus, the movement of cooling water in the circulation loop is reversed, which allows water from condenser 3, to be supplied to the incoming tubes of sector 8 from the louver 34 (the coldest air inlet) side. the temperature of which is higher than the temperature of the cooling water that was previously discharged from these tubes to the condenser 3. When the temperature of the cooling water rises above 16–17 ° C, operations are performed in reverse order to create the initial cooling water circuit. The cooling water is regulated by opening (closing) the louver 34 depending on the electrical load (steam consumption), changing the cooling water flow in sector 8, and also changing the cooling water flow to the condenser 3 by mixing water through the gate 19 to the jumper 15 or bypassing the gate 19. Thus, the use of the proposed method of operating a steam power plant allows, at lowered electrical loads and air temperatures, to significantly lower the cooling temperature. minutes water supplied to the condenser, thereby reducing the pressure in the condenser and increases the efficiency of the installation. The supply of water from the condenser to the sector from the air inlet side eliminates the possibility of freezing the tubes, which increases the reliability of the installation. Ensuring control of the temperature and flow rate of the cooling water allows the turbine to be deeply unloaded without reducing reliability and increasing its maneuverability.

Claims (1)

WAY OF OPERATION OF A STEAM POWER UNIT by controlling the steam flow to the turbine, condensing the steam in the condenser by supplying cooling water from the cooling tower through pressure pipelines and its outlets through the circulation pump through the discharge pipelines to the cooling tower sectors when controlling the temperature of cooling water, feeding through the condensate pump with condensate recirculation regenerative heaters and make-up water in the condenser, characterized in that, in order to increase maneuverability, reliability and efficiency in the period of negative air temperatures, when at least one sector output reaches a cooling water temperature of 13-15 ° С, cooling water is mixed from the discharge pipe after the circulation pump into the pressure pipe, the make-up water and condensate flow rate is increased for recirculation, and at the beginning of reduction temperatures of the cooling water from the source increase the supply of cooling water to the pressure pipe, reduce the flow rate of makeup water and turn off the condensate recirculation.