Automatic control system and method for deaerator heating steam regulating valve

Abstract

The invention discloses an automatic control system and method for a deaerator heating steam regulating valve. The system comprises a deaerator heating steam regulating valve control module. The input end of the deaerator heating steam regulating valve control module is connected to a deaerator steam pressure gauge and a deaerator water tank temperature gauge arranged on a deaerator water tank. The output end of the deaerator heating steam regulating valve control module is connected to a deaerator heating steam regulating valve arranged on a steam pipeline connected to a deaerator degassing tower. The deaerator heating steam regulating valve control module controls the opening of the deaerator heating steam regulating valve according to the pressure of the deaerator steam and the water temperature of the deaerator water tank, thereby maintaining the stability of the pressure of the deaerator steam and the water temperature of the deaerator water tank, and avoiding thermal shock of a metal pipe wall caused by excessive fluctuation of the water temperature of the deaerator water tank.

Description

Technical Field

[0001] The present invention belongs to the field of automatic control of thermal power plants, and relates to a deaerator heating control system of a boiler, and specifically to a system and method for automatically controlling a deaerator heating steam regulating valve by controlling the heating steam flow rate based on temperature and pressure states. Background Art

[0002] The deaerator is a core thermal equipment in a thermal power plant. The stability of the deaerator operation directly affects the quality of steam and the economic benefits of the power plant. The main function of the deaerator is to remove oxygen and other non-condensable gases in the water supply, ensure the quality of the water supply, reduce corrosion, and improve the efficiency of heat conduction. At the same time, the deaerator is also a hybrid heater in the feed water heat recovery heating system, which plays a role in heating the feed water and increasing the feed water temperature.

[0003] Figure 1 This is a schematic diagram of the typical deaerator heating system structure of a thermal power plant.

[0004] The oxygenated water enters the deaerator degassing tower 1 through the deaerator water supply valve 7 and reaches the deaerator water storage tank 2. The heating steam enters the deaerator degassing tower 1 through the deaerator heating steam regulating valve 6 to remove oxygen and other non-condensable gases from the feed water in the deaerator water storage tank 2, while heating the feed water and increasing the feed water temperature. The deaerator water storage tank 2 contains a mixture of steam, oxygenated water and deoxygenated water. The pressure gauge 3 is used to measure the pressure Ps of the deaerator steam. The thermometer 4 is used to measure the water temperature Tw of the deaerator water storage tank. The water level gauge 5 is used to measure the water level Lw of the deaerator water storage tank. The feed water pump 8 at the bottom outlet of the deaerator water storage tank 2 transports the deoxygenated water to the boiler feed water system.

[0005] The deaerator water supply valve 7 controls the water level of the deaerator water tank measured by the water level meter 5. The deoxygenated water coming out from the bottom of the deaerator water tank 2 directly enters the boiler feed pump 8, and its flow rate is controlled by the boiler water consumption. In order to facilitate the discharge of precipitated oxygen, the deaerator exhaust valve 9 at the top should be open to the air and not included in the automatic control. The control of the deaerator water supply valve 7, the boiler feed pump 8, and the top deaerator exhaust valve 9 are relatively mature. This patent mainly solves the control of the deaerator heating steam regulating valve 6.

[0006] The deaerator heating steam regulating valve 6 is usually controlled by taking the temperature Tw of the water in the deaerator water tank as the controlled object. However, since the temperature of the water in the deaerator water tank changes slowly, when the temperature is used as the control parameter, the water temperature in the water tank often reaches the saturation temperature. After reducing the steam volume, the pressure of the deaerator is too low, which not only causes a large amount of water vaporization, but also is not conducive to the smooth discharge of the precipitated oxygen, directly affecting the deoxygenation effect. That is, controlling by taking the temperature of the water in the deaerator water tank as the controlled object cannot ensure the stability of the deaerator steam pressure. In addition, the control process may cause the temperature Tw of the water in the deaerator water tank to change too quickly, causing thermal shock to the metal pipes of the deaerator.

[0007] When water is heated to boiling under atmospheric pressure, the saturation temperature of the water is equal to the atmospheric pressure at the steam-water interface, and the partial pressure of oxygen and other insoluble components in the water is equal to zero. At this time, the solubility of oxygen in water drops sharply, so it escapes from the water. This is the principle of thermal deoxygenation. In order to allow the gas in the deaerator to be discharged smoothly into the atmosphere, the deaerator is kept at a pressure slightly higher than the atmospheric pressure. Generally, the pressure in the deaerator is 0.01-0.05MPa higher than the atmospheric pressure, and the boiling temperature of water under this pressure is 102-110°C, that is, the stability of the water temperature Tw of the deaerator water storage tank and the pressure Ps of the deaerator steam should be guaranteed. Some thermal power generation unit control systems also design the deaerator heating steam regulating valve 6 to control the pressure Ps of the deaerator steam. However, in the process of controlling the deaerator pressure, since the water tank is operated at a micro-pressure, it is impossible to achieve accurate control of the pressure, resulting in very frequent operation of the steam valve, and at the same time, the water temperature in the deaerator temperature fluctuates too much, causing thermal shock to the metal pipes of the deaerator.

[0008] The current conventional control system and control method cannot achieve this control target. Excessive fluctuations in the water temperature Tw in the deaerator storage tank will cause thermal shock to the metal pipe wall of the deaerator. Power plant operators often switch the deaerator heating steam regulating valve to manual control, and frequent human intervention. Summary of the invention

[0009] In view of the above problems existing in the prior art, the present invention provides a system and method for automatically controlling the heating steam regulating valve of a deaerator by controlling the heating steam flow rate based on temperature and pressure conditions, thereby achieving stable control of the water temperature Tw of the deaerator water tank and the pressure Ps of the deaerator steam, and avoiding thermal shock on the metal pipe wall caused by excessive fluctuations in the water temperature Tw of the deaerator water tank.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A deaerator heating steam regulating valve automatic control system includes a deaerator heating steam regulating valve control module 10, the input end of the deaerator heating steam regulating valve control module 10 is connected to a deaerator steam pressure gauge 3 and a deaerator water tank temperature gauge 4 arranged on a deaerator water tank 2, the output end of the deaerator heating steam regulating valve control module 10 is connected to a deaerator heating steam regulating valve 6 arranged on a steam pipeline connected to a deaerator degassing tower 1, and the deaerator heating steam regulating valve control module 10 controls the opening of the deaerator heating steam regulating valve 6 by the pressure of the deaerator steam and the water temperature of the deaerator water tank, so as to maintain the stability of the pressure of the deaerator steam and the water temperature of the deaerator water tank.

[0012] The deaerator heating steam regulating valve control module 10 calculates the target value of the deaerator water tank temperature and the target value of the deaerator water tank temperature change rate according to the pressure of the deaerator steam measured by the deaerator steam pressure gauge 3 and the water temperature of the deaerator water tank measured by the deaerator water tank temperature gauge 4, thereby significantly reducing the temperature fluctuation amplitude during the deaerator heating process, while improving the stability of the deaerator steam pressure, increasing the matching degree of the deaerator temperature and pressure, and improving the deoxygenation effect.

[0013] A deaerator water tank water level gauge is provided on the deaerator water tank 2, and a feed water pump 8 is provided at the bottom of the deaerator water tank 2 to connect to the boiler feed water system.

[0014] The deaerator degassing tower 1 is connected to the oxygen-containing water pipeline through the deaerator water supply valve 7. A deaerator exhaust valve 9 is arranged on the top of the deaerator degassing tower 1, and the deaerator exhaust valve 9 is normally open to air.

[0015] The control method of the deaerator heating steam regulating valve automatic control system comprises the following steps:

[0016] Step 1: According to the pressure Ps of the deaerator steam measured by the deaerator steam pressure meter 3, the current saturation temperature Tws of the deaerator steam is obtained. Tws is the reference value of the temperature target value controlled by the deaerator heating steam regulating valve control module 10. The operator corrects the saturation temperature Tws of the deaerator steam within a certain range to obtain the target water temperature Tsp of the deaerator water tank controlled by the deaerator heating steam regulating valve control module 10; according to the water temperature Tw of the deaerator water tank measured by the deaerator water tank temperature meter 4, the actual change rate DTw of the water temperature of the deaerator water tank is calculated; the target water temperature Tsp of the deaerator water tank is compared with the water temperature Tw of the deaerator water tank, and the temperature change rate target value DTws is obtained by the difference △Tw between the water temperature Tw of the deaerator water tank and the temperature target value Tsp;

[0017] Step 2: The opening instruction AO of the deaerator heating steam control valve is obtained from the difference △DTw between the actual change rate DTw of the water temperature in the deaerator storage tank and the target value DTws of the temperature change rate; specifically, when △DTw is between -0.02 and 0.02, the current opening instruction AO of the deaerator heating steam control valve is kept unchanged; when △DTw>0.02, the opening instruction AO of the deaerator heating steam control valve is slowly increased at a certain rate, and the instruction increase rate is a function of △DTw; when △DTw<-0.02, the opening instruction AO of the deaerator heating steam control valve is slowly reduced at a certain rate, and the instruction reduction rate is a function of △DTw.

[0018] The control method can realize that when the water temperature Tw of the deaerator water tank is lower than the target water temperature Tsp of the deaerator water tank, the water temperature Tw of the deaerator water tank can be slowly increased to the target water temperature Tsp of the deaerator water tank at a set temperature change rate target value DTws; when the water temperature Tw of the deaerator water tank is higher than the target water temperature Tsp of the deaerator water tank, the water temperature Tw of the deaerator water tank can be slowly decreased to the target water temperature Tsp of the deaerator water tank at a set temperature change rate target value DTws; when the water temperature Tw of the deaerator water tank is consistent with the target water temperature Tsp of the deaerator water tank, the temperature change rate DTw is controlled to be 0°C / min, that is, the current water temperature Tw of the deaerator water tank is maintained.

[0019] According to the control method, during the entire control process, the opening instruction AO of the deaerator heating steam regulating valve will be slowly opened or closed at a rate of -0.1 to 0.1% / s, so that the temperature of the water in the deaerator water tank reaches the target temperature at a temperature change rate of -1 to 1°C / min. The whole process realizes stable control of the water temperature Tw of the deaerator water tank and the pressure Ps of the deaerator steam, avoiding thermal shock on the metal pipe wall caused by excessive fluctuation of the water temperature Tw of the deaerator water tank.

[0020] Compared with the prior art, the present invention has the following advantages: 1. During the heating process of the deaerator, when the target temperature differs greatly from the current temperature, the conventional control method cannot accurately control the temperature change rate during the heating process of the deaerator. The method of the present invention can control the temperature rise rate of the deaerator within less than 1°C / min during the heating process of the deaerator, so as to avoid thermal shock of the metal pipe wall caused by the rapid change of the water temperature of the deaerator water tank.

[0021] 2. The present invention takes the temperature change rate of the deaerator water tank as the controlled object, which can significantly reduce the fluctuation amplitude during the heating process of the deaerator, while improving the stability of the deaerator steam pressure, increasing the matching degree of the deaerator temperature and pressure, and improving the deoxidation effect.

[0022] 3. The present invention adopts a method of monotonically opening or closing the valve opening. When the deaerator temperature is close to the set value, the deaerator temperature change rate is controlled to be close to 0. Compared with the conventional PID control strategy, this method can effectively avoid the problems of deaerator valve fluctuation and system overshoot in the adjustment process, and enhance the overall stability of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of a typical deaerator heating system in a thermal power plant.

[0024] Figure 2 It is a schematic diagram of the connection between the deaerator heating system and the control system of the present invention.

[0025] Figure 3 This is a schematic diagram of the control method of the present invention.

[0026] Description of reference numerals:

[0027] 1 is a deaerator degassing tower, 2 is a deaerator water storage tank, 3 is a deaerator steam pressure gauge, 4 is a deaerator water storage tank temperature gauge, 5 is a deaerator water storage tank water level gauge, 6 is a deaerator heating steam regulating valve, 7 is a deaerator water supply valve, 8 is a feed water pump, 9 is a deaerator exhaust valve, and 10 is a deaerator heating steam regulating valve control module. DETAILED DESCRIPTION

[0028] like Figure 2 As shown, oxygenated water enters the deaerator degassing tower 1 through the deaerator water supply valve 7 and then reaches the deaerator water storage tank 2. The heating steam enters the deaerator degassing tower 1 through the deaerator heating steam regulating valve 6 to remove oxygen and other non-condensable gases from the feed water in the deaerator water storage tank 2, while heating the feed water and increasing the feed water temperature. The deaerator water storage tank 2 contains a mixture of steam, oxygenated water, and deoxygenated water. The deaerator steam pressure gauge 3 is used to measure the pressure Ps of the deaerator steam. The deaerator water storage tank temperature gauge 4 is used to measure the water temperature Tw of the deaerator water storage tank. The deaerator water storage tank water level gauge 5 is used to measure the water level Lw of the deaerator water storage tank. The feed water pump 8 at the bottom outlet of the deaerator water storage tank 2 transports the deoxygenated water to the boiler feed water system.

[0029] The pressure Ps of the deaerator steam measured by the pressure gauge 3 and the water temperature Tw of the deaerator water storage tank measured by the thermometer 4 are connected to the deaerator heating steam regulating valve control module 10, and the deaerator heating steam regulating valve control module 10 outputs a control instruction to the deaerator heating steam regulating valve 6.

[0030] The pressure Ps of the deaerator steam measured by the deaerator steam pressure gauge 3 and the water temperature Tw of the deaerator water tank measured by the deaerator water tank temperature gauge 4 are connected to the deaerator heating steam regulating valve control module 10. The deaerator heating steam regulating valve control module 10 outputs an instruction to control the opening instruction AO of the deaerator heating steam regulating valve, which is used to control the opening of the deaerator heating steam regulating valve 6 to maintain the stability of the pressure Ps of the deaerator steam and the water temperature Tw of the deaerator water tank.

[0031] The current saturation temperature Tws of the deaerator steam is obtained according to the pressure Ps of the deaerator steam measured by the deaerator steam pressure meter 3. The saturation temperature Tws of the deaerator steam is the reference value of the temperature target value controlled by the deaerator heating steam regulating valve control module 10. The operator can correct the saturation temperature Tws of the deaerator steam within a certain range, such as within the range of -20 to +20°C, to obtain the target value Tsp of the water temperature of the deaerator water tank controlled by the deaerator heating steam regulating valve control module 10. According to the water temperature Tw of the deaerator water tank measured by the deaerator water tank temperature meter 4, the actual change rate DTw of the water temperature of the deaerator water tank is calculated, and the target value Tsp of the water temperature of the deaerator water tank is compared with the water temperature Tw of the deaerator water tank, and the target value DTws of the temperature change rate is obtained by the difference △Tw (△Tw=Tw-Tsp) between the water temperature Tw of the deaerator water tank and the temperature target value Tsp.

[0032] The difference △DTw (△DTw=DTw-DTws) between the actual change rate of water temperature in the deaerator water tank and the target value of the temperature change rate DTws is used to obtain the opening instruction AO of the deaerator heating steam control valve. Specifically, when △DTw is between -0.02 and 0.02, the opening instruction AO of the current deaerator heating steam control valve is kept unchanged; when △DTw>0.02, the opening instruction AO of the deaerator heating steam control valve is slowly increased at a certain rate, and the instruction increase rate is a function of △DTw; when △DTw<-0.02, the opening instruction AO of the deaerator heating steam control valve is slowly reduced at a certain rate, and the instruction reduction rate is a function of △DTw.

[0033] This embodiment provides a method and method for controlling the heating steam flow rate of a deaerator heating steam regulating valve based on temperature and pressure conditions, such as Figure 3 As shown, specifically:

[0034] 1. The saturated temperature Tws of the deaerator steam is obtained according to the pressure Ps of the deaerator steam measured by the deaerator steam pressure table 3, in units of °C. That is, the saturated temperature Tws of the deaerator steam is a function of the pressure Ps of the deaerator steam, Tws = F1 (Ps). For the specific functional relationship, please refer to the comparison table of the saturated steam temperature of the deaerator steam and the pressure of the deaerator steam. The typical functional relationship between Tws and Ps is shown in Table 1 below.

[0035] Table 1

[0036]

[0037]

[0038] 2. The saturated temperature Tws of the deaerator steam is the reference value of the temperature target value controlled by the deaerator heating steam regulating valve control module 10. The operator can correct Tws within a certain range, such as within the range of -20 to +20°C, to obtain the deaerator water storage tank water temperature target value Tsp controlled by the deaerator heating steam regulating valve control module 10, in units of °C.

[0039] 3. According to the deaerator water tank water temperature Tw measured by the deaerator water tank temperature table 4, the actual change rate DTw of the deaerator water tank water temperature is calculated, in units of ℃ / min.

[0040] 4. The temperature change rate target value DTws is obtained from the difference △Tw between the deaerator water tank water temperature Tw and the deaerator water tank water temperature target value Tsp (△Tw=Tw-Tsp), in units of ℃ / min. That is, the temperature change rate target value DTws is a function of the temperature difference △Tw, DTws=F2(△Tw). The typical functional relationship between DTws and △Tw is shown in the following table.

[0041] Table 2

[0042] △Tw DTws(℃ / min) <-2 1 -2～-0.5 -0.5*△Tw -0.5～0.5 0 0.5～2 -0.5*△Tw >2 -1

[0043] That is, if the difference △Tw between the deaerator water tank water temperature Tw and the deaerator water tank water temperature target value Tsp is larger, the temperature change rate target value DTws is smaller; the smaller △Tw is, the larger the temperature change rate target value DTws is, and the temperature change rate target value DTws is within the range of -1 to 1℃ / min.

[0044] 5. The change rate dO of the opening instruction of the deaerator heating steam control valve is obtained from the difference △DTw (△DTw=DTw-DTws) between the actual change rate DTw of the water temperature in the deaerator storage tank and the target value DTws of the temperature change rate. That is, the change rate dO of the opening instruction of the deaerator heating steam control valve is a function of the temperature change rate difference △DTw, dO=F3(△DTw). The typical functional relationship between dO and △DTw is shown in the following table.

[0045] Table 3

[0046] △DTw dO(% / s) <-1 0.1 -0.02～1 △DTw×(-0.1) -0.02～0.02 0 0.02～1 △DTw×(-0.1) >1 -0.1

[0047] 6. Based on the above table, when △DTw is between -0.02 and 0.02, keep the current opening instruction AO of the deaerator heating steam control valve unchanged; when △DTw>0.02, slowly increase the opening instruction AO of the deaerator heating steam control valve at a rate of dO (% / s); when △DTw<-0.02, slowly reduce the opening instruction AO of the deaerator heating steam control valve at a rate of dO (% / s). The change rate dO of the opening instruction AO of the deaerator heating steam control valve is controlled between -0.1 and 0.1% / s. That is, in the entire control process, the opening instruction AO of the deaerator heating steam control valve is slowly opened or closed in the range of 0 to 100%.

[0048] The present invention provides a system and method for automatically controlling a deaerator heating steam regulating valve by controlling the heating steam flow rate based on temperature and pressure states. When the water temperature Tw of the deaerator water tank is lower than the target water temperature Tsp of the deaerator water tank, the water temperature Tw of the deaerator water tank can be slowly increased to the target water temperature Tsp of the deaerator water tank at a set temperature change rate DTws. When the water temperature Tw of the deaerator water tank is higher than the target water temperature Tsp of the deaerator water tank, the water temperature Tw of the deaerator water tank can be slowly reduced to the target water temperature Tsp of the deaerator water tank at a set temperature change rate DTws. When the water temperature Tw of the deaerator water tank is consistent with the target water temperature Tsp of the deaerator water tank, the temperature change rate DTw is controlled to be 0°C / min, that is, the current water temperature Tw of the deaerator water tank is maintained.

[0049] The present invention provides a system and method for automatically controlling the heating steam regulating valve of a deaerator by controlling the heating steam flow rate based on the temperature and pressure state. During the entire control process, the opening instruction of the heating steam regulating valve of the deaerator will be slowly opened or closed at a rate of -0.1 to 0.1% / s. The temperature of the water in the deaerator water storage tank reaches the target temperature at a temperature change rate of -1 to 1°C / min. The whole process realizes stable control of the water temperature Tw of the deaerator water storage tank and the pressure Ps of the deaerator steam, avoiding thermal shock on the metal pipe wall caused by excessive fluctuations in the water temperature Tw of the deaerator water storage tank.

Claims

1. A control method for a deaerator heating steam regulating valve automatic control system, the automatic control system comprising a deaerator heating steam regulating valve control module (10), the input end of the deaerator heating steam regulating valve control module (10) being connected to a deaerator steam pressure gauge (3) and a deaerator water tank temperature gauge (4) arranged on a deaerator water tank (2), the output end of the deaerator heating steam regulating valve control module (10) being connected to a deaerator heating steam regulating valve (6) arranged on a steam pipeline connected to a deaerator degassing tower (1), the deaerator heating steam regulating valve control module (10) controlling the opening of the deaerator heating steam regulating valve (6) by the pressure of the deaerator steam and the water temperature of the deaerator water tank, so as to maintain the stability of the pressure of the deaerator steam and the water temperature of the deaerator water tank; It is characterized in that The control method comprises the following steps: Step 1: The current saturation temperature Tws of the deaerator steam is obtained according to the pressure Ps of the deaerator steam measured by the deaerator steam pressure gauge (3), Tws being the reference value of the temperature target value controlled by the deaerator heating steam regulating valve control module (10). The operator corrects the saturation temperature Tws of the deaerator steam within a certain range to obtain the target value Tsp of the water temperature of the deaerator water tank controlled by the deaerator heating steam regulating valve control module (10); the actual change rate DTw of the water temperature of the deaerator water tank is calculated according to the water temperature Tw of the deaerator water tank measured by the deaerator water tank temperature gauge (4); Compare the target water temperature value Tsp of the deaerator water tank with the water temperature Tw of the deaerator water tank, and obtain the target temperature change rate value DTws from the difference △Tw between the water temperature Tw of the deaerator water tank and the temperature target value Tsp; Step 2: The opening instruction AO of the deaerator heating steam control valve is obtained from the difference △DTw between the actual change rate DTw of the water temperature in the deaerator storage tank and the target value DTws of the temperature change rate; specifically, when △DTw is between -0.02 and 0.02, the current opening instruction AO of the deaerator heating steam control valve is kept unchanged; when △DTw>0.02, the opening instruction AO of the deaerator heating steam control valve is slowly increased at a certain rate, and the instruction increase rate is a function of △DTw; when △DTw<-0.02, the opening instruction AO of the deaerator heating steam control valve is slowly reduced at a certain rate, and the instruction reduction rate is a function of △DTw.

2. The control method according to claim 1, characterized in that: The deaerator heating steam regulating valve control module (10) calculates a target value of the deaerator water tank temperature and a target value of the deaerator water tank temperature change rate according to the pressure of the deaerator steam measured by the deaerator steam pressure gauge (3) and the water temperature of the deaerator water tank measured by the deaerator water tank temperature gauge (4), thereby significantly reducing the temperature fluctuation amplitude during the deaerator heating process, improving the stability of the deaerator steam pressure, increasing the matching degree of the deaerator temperature and pressure, and improving the deoxidation effect.

3. The control method according to claim 1, characterized in that: A deaerator water tank water level gauge is arranged on the deaerator water tank (2), and a feed water pump (8) is arranged at the bottom of the deaerator water tank (2) to be connected to the boiler feed water system.

4. The control method according to claim 1, characterized in that: The deaerator degassing tower (1) is connected to the oxygen-containing water pipeline through the deaerator water supply valve (7). A deaerator exhaust valve (9) is arranged on the top of the deaerator degassing tower (1). The deaerator exhaust valve (9) is normally open to air.

5. The control method according to claim 1, characterized in that: When the water temperature Tw of the deaerator water tank is lower than the target value Tsp of the water temperature of the deaerator water tank, the water temperature Tw of the deaerator water tank can be slowly increased to the target value Tsp of the water temperature of the deaerator water tank at the set temperature change rate target value DTws; When the water temperature Tw of the deaerator water tank is higher than the target value Tsp of the water temperature of the deaerator water tank, the water temperature Tw of the deaerator water tank is slowly reduced to the target value Tsp of the water temperature of the deaerator water tank at the set temperature change rate target value DTws; When the water temperature Tw of the deaerator water tank is consistent with the target value Tsp of the water temperature of the deaerator water tank, the temperature change rate DTw is controlled to be 0°C / min, that is, the current water temperature Tw of the deaerator water tank is maintained.

6. The control method according to claim 1, characterized in that: During the entire control process, the opening instruction AO of the deaerator heating steam regulating valve will slowly open or close at a rate of -0.1 to 0.1% / s, so that the temperature of the water in the deaerator water tank reaches the target temperature at a temperature change rate of -1 to 1°C / min. The entire process achieves stable control of the deaerator water tank water temperature Tw and the deaerator steam pressure Ps, avoiding thermal shock to the metal pipe wall caused by excessive fluctuations in the deaerator water tank water temperature Tw.

Images