KR20230069191A - Steam generator with desuperheater - Google Patents

Abstract

The present invention relates to a steam generator (01) and a steam generating system in which heat exchangers (11) are arranged in a hot gas path (02). A desuperheater (22) is arranged to protect the installations and increase the efficiency at the output of at least a plurality of heat exchangers (11), each heat exchanger (22) having a fluid distribution valve (23) with a distribution pipe (21). ) is connected through

Description

Steam generator with desuperheater

The present invention relates to steam generators and steam generation systems, and in particular to protection of steam generators and additional steam turbines against rapid increases in steam temperature and efficient heat transfer from hot gases to an evaporation medium.

Power plants often combine gas turbines and steam turbines to produce electrical energy with high efficiency. Generally, steam generators are used to convert hot gases from a gas turbine into hot steam for use in a steam turbine.

Accordingly, a typical steam generator first includes a hot gas path from a hot gas input to a waste gas output. Inside the hot gas path, several heat exchangers are arranged, starting from the economizer on the waste gas output side and passing through a further series of heat exchangers to the superheater on the hot gas output side. The temperature of the fluid passing through the heat exchanger increases from one heat exchanger to the next, and in this process, cold water is supplied to the economizer and hot steam is discharged from the superheater.

Gas turbines rapidly increase the temperature of the hot gases exiting the gas turbine so that they can respond quickly to requests for electrical energy. Without protection, there is a risk of very high thermal stresses due to rapid temperature changes, especially in steam turbines.

A common solution to this is to place an attemperator in the piping from the steam generator to the steam turbine. The desuperheater is used to inject water into the hot steam after the superheater, thereby reducing the temperature of the hot steam delivered to the steam turbine.

The use of desuperheaters to protect steam turbines is well established, but there is no protection for the steam generator itself upstream of the desuperheater (following the steam flow). The peak temperature and peak temperature change occur on the superheater outlet side close to the hot gas inlet of the hot gas path. Due to this, high thermal stress is generated inside the pipe from the superheater to at least the position of the desuperheater, and accordingly, the size of the equipment used becomes excessively large.

Therefore, other solutions are known in the state of the art, whereby a desuperheater is placed between the penultimate and last heat exchangers. Compared to the solutions described above, less stress is placed on the superheater itself and consequently on the piping at the superheater outlet.

However, the method of placing the desuperheater in front of the superheater has a disadvantage in that the ability to control the temperature of the hot steam at the superheater output is poor. This can result in a loss in efficiency during start-up of the power plant or during rapid power output increases.

Another disadvantage of the conventional general system is that the control of the desuperheater is very sensitive. In order to avoid overshoot that occurs when the steam temperature is sensitively controlled by opening and closing the valve from the chilled water line to the desuperheater, it is generally necessary to keep a longer distance between the actual temperature/temperature change and the allowable temperature/temperature change during operation, especially during start-up. You have to keep a lot of distance.

As a result, placing the desuperheater before the superheater does not improve with respect to the required distance between the actual temperature/temperature change and the allowable temperature/temperature change during operation.

It is also known in the state of the art that once-through steam generators can react slowly to temperature changes due to the long travel time of the feedwater through all the heat exchangers towards the superheater outlet.

Therefore, the object of the present invention is to be able to control the temperature of high-temperature steam well and quickly, and to protect the pipe of the output side superheater and the pipe of the steam turbine from rapid temperature change.

The problem of the present invention is solved by a steam generator according to claim 1 . A steam generating system enabling operation is described in claim 4 . A method of operating the steam generating system is described in claim 7 . The further claims set forth the effective advantages of the invention.

A common type of steam generator has a casing with an internal hot gas path through the casing from the hot gas input to the waste gas output. The steam generator includes a plurality of heat exchangers disposed at least partially within the hot gas path.

A superheater, one of the plurality of heat exchangers, is disposed near the hot gas input. The superheater further includes a superheater output connected to additional equipment such as a steam turbine for delivering a flow of hot steam. The superheater further includes a superheater input.

In addition, a first heat exchanger is disposed in the hot gas path. It similarly includes a first output and a first input. Here, the first output unit is connected to the superheater input unit.

Next, a second heat exchanger is disposed in the hot gas path. It similarly includes a second output and a second input. Here, the second output unit is connected to the first input unit.

Next, a third heat exchanger is disposed in the hot gas path. It similarly includes a third output and a third input. Here, the third output unit is connected to the second input unit.

Next, a fourth heat exchanger is disposed in the hot gas path. It similarly includes a fourth output and a fourth input. Here, the fourth output unit is connected to the third input unit.

In other embodiments, a fifth heat exchanger may be placed in series next to the fourth heat exchanger, or more heat exchangers may be placed in series, each having a fluid input and a fluid output.

Finally, an economizer is placed in the hot gas path. It similarly includes an economizer output and an economizer input. Here, the economizer output is connected to the fluid input of the last heat exchanger. The economizer input is connected to a source of cooling fluid. In typical solutions, water is used as the fluid, but other fluids can be used as long as they are capable of evaporation.

Reference numerals to heat exchangers and related components are made in the context opposite to the direction of flow through the heat exchanger. Therefore, the heat exchanger connected to the superheater is referred to as the first heat exchanger, and the heat exchanger connected to the economizer is referred to as the last heat exchanger.

The superheater, heat exchangers, and economizer need not be arranged next to each other and/or sequentially within the hot gas path. Further, other features or other heat exchangers not connected along the series of heat exchangers according to the generic solution may be arranged in the hot gas path and also between the heat exchangers of the generic solution.

Also, the superheater, heat exchangers, and economizer need not be directly connected to each other. Further devices, eg other heat exchangers or vessels, can be arranged between the superheater and/or heat exchanger and/or economizer according to the general solution. However, a preferred solution is to connect directly from the superheater to the first heat exchanger, and from the first heat exchanger to the second heat exchanger, in this way the last heat exchanger in the series is connected to the economizer.

Each superheater, heat exchanger, and economizer includes a fluid input connected to an additional heat exchanger or other part of the steam generator. In operation, a low-temperature fluid (eg, water and/or steam) is supplied to the fluid input. The fluid inlet is connected to one or more distribution pipes to divide the fluid flow into other pipes. Each of the superheater, heat exchangers, and economizer includes a plurality of heat exchange tubes, each heat exchange tube being respectively connected to one of the distribution pipes. The heat exchange tube is disposed at least partially, in particular entirely, inside the hot gas path. During operation, when the hot gas flows along the hot gas path through the heat exchangers, the heat of the hot gas is transferred to the fluid (eg water/steam) inside the heat exchange tubes. Each heat exchange tube is connected to a collection pipe, and each superheater, heat exchangers, and economizer includes one or more collection pipes for collecting hot fluid from the heat exchange tubes. The collection pipe is connected to a fluid output that serves to connect to an additional heat exchanger or other installation (eg steam turbine).

The steam generator further includes distribution piping for dispensing a specific type of fluid.

A first desuperheater is disposed in a pipe from the first output of the first heat exchanger to the superheater input. The first desuperheater includes a connection to the distribution piping, at which connection to the distribution piping is disposed a first fluid distribution valve for controlling flow from the distribution piping to the first desuperheater.

In order to improve the control stability of the steam generator for the solution of the present invention, desuperheaters are additionally provided in the heat exchangers.

Accordingly, the second desuperheater is disposed in the pipe from the second output of the second heat exchanger to the first input of the first heat exchanger. The second desuperheater also includes a connection to the distribution piping, at which connection there is disposed a second fluid distribution valve for controlling flow from the distribution piping to the second desuperheater.

In addition, a third dehumidifier is disposed in a pipe from the third output unit to the second input unit. The third desuperheater also includes a connection to the distribution piping at which a third fluid distribution valve for controlling flow from the distribution piping to the third desuperheater is disposed.

Next, a fourth dehumidifier is disposed in the pipe from the fourth output unit to the third input unit. The fourth desuperheater also includes a connection to the distribution piping, at which connection there is disposed a fourth fluid distribution valve for controlling flow from the distribution piping to the fourth desuperheater.

If an additional heat exchanger is disposed between the fourth heat exchanger and the economizer, an additional desuperheater may be disposed at each connection from one heat exchanger to the next in the series of heat exchangers. In this embodiment, it is more effective to place each fluid distribution valve at the connection from the additional desuperheater to the distribution piping.

According to the solution of the present invention, the desuperheater needs to be supplied with fluid. Thus, the distribution piping is connected to the economizer output. Additional connections can be made from the distribution piping to the source of cooling fluid to allow temperature and flow control through the distribution piping. Through this, since the warm fluid (eg, hot water) that is not evaporated can be supplied to other thermostats, the temperature can be effectively controlled while increasing efficiency.

Each desuperheater may include one or more fluid nozzles to introduce a cooling fluid (eg, water) to steam flowing through, for example, a connection from one heat exchanger in the series to the next heat exchanger or superheater. The fluid nozzle itself is connected to the distribution piping as a source of cooling fluid for the desuperheater. The flow of cooling fluid from the distribution piping to the fluid nozzles can be controlled using respective fluid distribution valves.

As a result, steam generation can be improved by adding fluid to the evaporator section, shortening the travel time and improving the response time, and as the desuperheater fluid is added in the boiling environment, the fluid temperature remains basically constant, so energy loss does not increase.

According to a preferred embodiment, the main valve is arranged between the input of the last heat exchanger before the economizer and the economizer output. Through this, it is possible to control the flow of the fluid flowing into the last heat exchanger.

According to another solution, the fluid supply valve is arranged at the economizer input or at the economizer output. This allows you to control the flow of fluid through the economizer.

A bypass to the economizer may be used if the flow of fluid through the economizer must be shut off or if the flow of fluid through the economizer is not sufficient to supply the final heat exchanger and distribution piping. To allow flow control through the bypass, an effective solution is to place a fluid bypass valve at the connection from the distribution piping to the cooling fluid source.

According to a preferred solution, the main desuperheater is arranged at the output of the superheater to allow effective control of the steam temperature at the output of the superheater. The main desuperheater is also connected to the distribution piping through a desuperheater distribution valve disposed within this connection. This enables precise control of the steam temperature, especially during start-up of the steam turbine.

In order to protect the piping between the heat exchangers, in particular the piping of the superheater output, the desuperheaters are advantageously arranged in at least two collection pipes of the heat exchanger and/or preferably in the superheater. In particular, it is effective to place the desuperheater within the existing collection pipes of each of the heat exchanger and superheater.

When the desuperheater is provided in the collection pipe, the temperature of the high-temperature fluid (eg, steam) can be effectively controlled at the output of each of the heat exchanger and the superheater by rapidly responding to changes in heat input. Additionally, the fluid output line can be protected from rapid temperature changes. As a result, an increase in service life can be expected in particular and, in the best case, restrictions on the start-up of the steam generator can be dispensed with.

The solution of arranging a desuperheater in the trapping pipe is the best compromise between trying to implement a cooling solution and protection against thermal stress.

Here, each desuperheater needs to be connected to a distribution pipe, and a fluid distribution valve is used to connect the desuperheaters to each of the heat exchanger and the superheater to simultaneously flow the cooling fluid of all desuperheaters of the heat exchanger and the superheater. You can control it.

It is more effective if two or more fluid distribution valves are used for the first implementation above. In this case, each fluid distribution valve is used to control the flow of cooling fluid to at least one desuperheater. With the second approach, the steam temperature can be individually controlled at the output of each collection pipe.

In the following, "fluid valve" means one, and "fluid valves" means at least two of the previously mentioned valves actually implemented in the steam generating system. in other words,

- the main valve at the fluid input of the last heat exchanger;

- fluid supply valve at the economizer input;

- a fluid bypass valve at the upstream end of the distribution piping, and

- Respective fluid distribution valves disposed between each desuperheater and distribution piping

One of the advantages is that a simple on-off valve can be employed when using serval fluid valves, whereby the number of fluid valves to open during operation depends on the temperature of the hot steam.

The highest temperature inside the heat exchangers can be expected upstream of the hot gas input (for the flow of hot gas through the steam generator). Therefore, it is effective when at least two desuperheaters in the collection pipe are arranged in the superheater, particularly when they are arranged at the hot gas input.

The steam generator of the present invention enables the steam generating system of the present invention including the steam generator of the present invention as described above. Here, the steam generating system needs to include a control system. A control system is coupled with the fluid valves to control the open position of each fluid valve. Control System In particular, it is effective if a plurality of fluid valves in a steam generator can be individually controlled to enable the desired operation of the steam generation system for each of the plurality of heat exchangers and superheaters.

In addition, it is effective if a different number of fluid valves can be controlled as a group while being dependent on each other.

Optimal control is more effective if the control system can step-by-step control at least some of the fluid valves to match the required strength of the fluid flow from the distribution piping to each desuperheater.

Two different types of information about the condition of the steam generator can advantageously be used to control the steam generation system.

In a first embodiment, the steam generation system further includes a temperature determining system, and the temperature determining system includes a temperature sensor. Through the temperature sensor, the temperature determination system can determine at least the temperature of the hot steam exiting each of the heat exchangers and superheater or the temperature of the piping at the fluid outlet.

The temperature determination system must be able to determine the actual temperature of the fluid at the fluid output of each heat exchanger and superheater. For example, a temperature sensor can be applied inside the fluid output. Alternatively, it may be sufficient to measure the temperature of the fluid outlet, i.e. the tube itself, and then it should also be possible to calculate the temperature of the hot steam inside the fluid outlet.

To improve multiple fluid valve control, preferred embodiments further include at least one additional temperature sensor. This may be added as a first temperature sensor, a second temperature sensor, which may be added to the steam and/or piping before or after the second desuperheater (e.g., at the second output of the second heat exchanger). temperature can be measured.

The third temperature sensor may preferably measure the temperature of the steam and/or piping before or after the third desuperheater.

In order to analyze the temperature in the other desuperheaters, an additional temperature sensor can preferably be applied in the same way for each of the additional heat exchangers and the superheater.

When using a temperature determination system capable of determining multiple temperatures in multiple desuperheaters, the control system can individually control different fluid valves according to different temperatures in each desuperheater.

For the second embodiment of the steam generation system of the present invention, a steam crystal system is required. Here, the vapor determination system should be able to determine at least one vapor ratio in the fluid inside the piping before and after one of the desuperheaters.

Initially, the proportion of vapor in the fluid flow is largely irrelevant if the amount of vapor or amount of liquid water is used. The ratio may then be determined in terms of volume or mass.

However, it is preferred to define the amount of vapor in the mass flow as the share of vapor.

If the mass flow from the distribution piping to the first desuperheater and through the desuperheater is known, the steam ratio can be calculated on the other side of the desuperheater (if the steam ratio measurement is provided upstream, then on the downstream side). can be determined and vice versa).

Similar to temperature determination, it is advantageous if the vapor determination system can determine the vapor in the additional desuperheater.

When using a steam determination system capable of determining the steam ratio in multiple desuperheaters, the control system can individually control different fluid valves according to the steam ratio in each desuperheater.

According to the third embodiment, the steam generation system combines the first and second embodiments with a temperature determination system and a steam determination system. At this time, the steam generation system may control the fluid valve according to the ratio of the steam analyzed in the desuperheater and each temperature change of the measured temperatures together with the control system.

The new steam generation system described above enables a new inventive method of controlling the steam generation system. Various implementations are possible depending on the decision system used.

Since the steam generation system includes a temperature determination system in the first stage, it is necessary to determine the actual temperature at the fluid output of the heat exchanger. As explained earlier, this may be the temperature of the pipe itself or the temperature of the fluid inside the pipe. In the first case, the temperature of the fluid must be estimated, and in the second case, the temperature of the pipe must be estimated.

Additionally, you can check the actual temperature change.

Second, the actual temperature must be compared with a preset value.

In a third step, at least one fluid valve is controlled according to the result of the comparison between the actual temperature/temperature change and a preset value. At this time, at least one fluid valve can be opened or closed.

Preferably, the fluid valves can be opened in stages and/or multiple fluid valves can be opened/closed.

The control system may compare the determined actual temperature or change in temperature to a preset value, and as a result, if the actual temperature or change in temperature exceeds the preset value, the control system may, in most cases, shut down at least one of the plurality of fluid valves. You can control fluid valves.

According to the first obvious solution, the preset value could be the maximum permissible temperature. When the actual temperature exceeds the maximum temperature, the fluid distribution valve opens and the cooling fluid flows into the steam, reducing the temperature of the fluid and piping.

The introduction of a cooling fluid (e.g. water) into a fluid (steam, hot water) at the output of the heat exchanger and superheater, respectively, in certain situations, in particular where there is a risk that the temperature is too high or the temperature rises too rapidly. may be needed in some cases.

According to another embodiment, the maximum temperature change may be used as a preset value. When the increase in main temperature exceeds the maximum temperature change, at least one fluid dispensing valve is triggered to open. This will reduce or stop the higher steam and piping temperatures.

In addition, the two limits can be used together to analyze the risk of reaching an unacceptable temperature or reaching an unacceptable temperature.

The input to the temperature determination system should allow the control system to calculate the necessary response to protect the steam generating system and subsequent installations from overheating or from increasing heat too quickly. Therefore, the control system must be connected with the fluid valves. If the preset value is exceeded, the control system may open one or more fluid valves accordingly.

The maximum temperature may be used as a preset value for triggering the opening of the at least one fluid valve. It is also possible to use the maximum permissible temperature change as a preset value.

In addition, a preset value may be defined as the maximum temperature according to the actual temperature change. A predefined dependence of the maximum temperature on the temperature change may, for example, define a higher maximum temperature if the temperature change is small and a lower maximum temperature if the temperature change is large.

The maximum temperature change according to the actual temperature can be used as a preset value. In this case, for example, a larger maximum temperature change may be allowed at a lower temperature and a smaller maximum temperature change may be allowed at a higher temperature. As a result, faster temperature changes in the noncritical temperature range can be tolerated with faster increases in power output, and smaller protective temperature changes are applied when the temperature reaches the relevant material limit.

Preferably, the temperature of the fluid at the fluid output and/or the temperature of the fluid output is related to triggering the opening of the fluid valve if it exceeds a preset value to trigger the control system and also protect the installations.

It is clear that the actual temperature as well as the actual temperature change is used when using the maximum temperature change as the preset value.

It is also possible to use a characteristic curve as a preset value as well as one fixed preset value. The characteristic curve may have a predefined maximum temperature, which may vary in value as the temperature changes. In this case, the characteristic curve is predefined. As a result, the control system can use the characteristic curve to derive a preset value different from the actual temperature change.

Conversely, the characteristic curve can also be defined as a predefined maximum temperature change whose value depends on the temperature. This can obtain a predefined value as a comparison value for a control system where the maximum temperature change depends on the actual temperature.

In order to more effectively control the steam generation system, the distance between the actual temperature change and the actual temperature of each of the permissible process conditions as well as the comparison of the temperature/temperature change with a preset value may additionally be taken into account. Thus, advantageously the difference between the actual temperature change and the preset value, respectively, is calculated.

In another valid step, a trend analysis can be performed on the actual temperature. Therefore, the actual temperature must be recorded over a period of time. The expected temperature can be calculated using the data of the past temperature and the current temperature. It can compare not only the actual temperature and the preset value, but also the expected temperature, and furthermore, the expected temperature and the preset value. You can also determine the difference. This information allows further predictive actuation of fluid valves.

An effective method uses a steam generation system capable of determining the temperature/temperature change at all fluid outputs of all heat exchangers and superheaters respectively. It compares all actual temperatures/temperature changes to their respective preset values, and can control both the fluid valves subject to comparison and the fluid valves subject to each comparison and the fluid valves subject to comparison other than each desuperheater. .

In another step, the fluid distribution valves are opened according to the distance between the current situation and the acceptable situation. Therefore, if there is a difference, it is more effective to open some of the fluid distribution valves of the plurality of fluid distribution valves according to the calculated difference. Here, "fluid valves to open" can be selected according to additional rules.

If there is not only an on-off state of the fluid valve, the protection of the steam generator can be improved and the efficiency can be increased. According to an effective solution, the at least one fluid dispensing valve can be opened in stages depending on, for example, the actual temperature or the difference between a temperature change and a preset value. Analogously, the fluid valves to be triggered may be selected according to additional rules.

Obviously, it is also possible to implement a control system that individually opens multiple fluid valves in stages using both options.

A preferred solution with an additional temperature sensor can be used in a more advantageous way to operate the steam generation system. At this time, in the first step, it is necessary to determine at least one additional temperature. This is either the main temperature of the main temperature sensor at the fluid output of the superheater or the first temperature of the first temperature sensor at the first fluid output of the first heat exchanger or the second temperature of the second fluid output of the second heat exchanger. It may be the second temperature of the temperature sensor. In addition, the main temperature change, each first temperature change, each second temperature change (etc.) can be determined respectively.

In this example with multiple actual temperatures in the next step, each of the main and first and second temperatures/temperature changes (etc.) is associated with the main, first, second, third, and fourth preset values (etc.) respectively. should be compared

Calculation of the difference allows in a stepwise manner to control each fluid dispensing valve and preferably other fluid valves depending on the determined difference in the next step.

In a simple solution, it is clear that all fluid valves are controlled simultaneously (open, closed). However, in a preferred solution the control system can individually control multiple fluid valves. Here, it is more effective if the main fluid distribution valve, the first fluid distribution valve and the second fluid distribution valve (if available, etc.) are individually controlled according to whether or not each exceeds a preset value.

The temperature and each temperature change is recorded over a period of time to enable predictive control of the steam generation system in an effective manner. At this time, it is effective to record some or all temperatures in all thermostats for a certain period of time.

With this collected data, trend analysis can be performed and expected future temperatures and respective future temperature changes can be calculated.

In the next step, the actual temperature as well as the respective temperature change is calculated. Thus, the currently determined actual temperature and each temperature change can be compared with the previous expected value.

It is clear that the same comparison can be performed for further determined temperatures/temperature changes.

In another effective control method, the difference between the temperature change of each last actual temperature and the corresponding previously determined expected value can be calculated.

Second, it is possible to compare the expected value with a preset value corresponding thereto.

In a more effective control method, the difference between the predicted value and the corresponding preset value can be calculated.

As a result, a number of fluid valves are opened and/or fluid valves are opened in stages according to a comparative or preferably calculated difference. This allows predictive control of the steam temperature.

The new steam generation system as described above also enables a second method for controlling the steam generation system. Accordingly, there is again a need for a steam generating system according to any of the foregoing descriptions. This should include a vapor crystal system. This second method includes the following steps:

If the steam generation system includes a steam determination system as the first step, the actual steam percentage of the fluid flowing through the piping before and after the desuperheater must be determined.

Regardless of whether the steam proportion is measured before or after the desuperheater, knowledge of the mass flow from the distribution piping to this desuperheater should allow for sufficiently accurate calculation of the vapor proportion on the other side of the desuperheater.

Similar to the use of a determined temperature, the actual vapor fraction should be compared to a preset value.

In a next step according to the comparison, the control system may control the at least one fluid valve.

The preset value may be a maximum or minimum allowable percentage of steam. Alternatively, the preset value may be a target steam ratio of steam. If the maximum allowable vapor rate is set, the (additional) opening of the fluid dispensing valve can be triggered if the actual vapor rate exceeds the maximum allowed vapor rate. On the other hand, a (further) closing of the fluid dispensing valve can be triggered if the percentage of steam is less than a predefined minimum vapor percentage.

It is effective to determine the difference between the actual percentage of steam and the preset value.

It is effective to open the at least one fluid dispensing valve according to the determined difference between the actual steam ratio and the respective preset value (eg target steam ratio), especially if the difference is known.

The steam rate can preferably be additionally determined in the additional desuperheater. It is very effective if you can determine the percentage of steam in all desuperheaters.

Regarding the control of the fluid valves, the same effective solution applies as the method using a temperature determining system. Therefore, it is effective when opening the fluid valves step by step and/or in groups.

It is more effective to set preset values for the ratio of steam to multiple heat exchangers in order to sufficiently protect the steam generator and subsequent facilities and to reach the maximum usable efficiency of the steam generator.

Here, except for the superheater, it is effective if the preset value indicates a steam ratio of at least 60% at the output of each heat exchanger (determined at the position before the next desuperheater). It is particularly effective when the proportion of steam is 75% or more.

On the other hand, it is effective that the steam ratio does not reach 100% at the output of the heat exchangers except for the superheater. Therefore, as for the preset value, a vapor ratio of 90% or less is effective. It is particularly effective when the preset value is a steam ratio of 85% or less.

Similar to the method of controlling a steam generation system comprising a temperature determination system, advantageous features also advantageously apply to the method of controlling a steam generation system comprising a steam determination system.

Therefore, it is effective to determine the ratio of steam in multiple desuperheaters. It is particularly effective to determine the proportion of steam in all desuperheaters.

Next, it is effective to control several or all fluid valves, and in particular, stepwise control according to the steam ratio in several or all desuperheaters is effective.

Similarly, a number of preset values can be used to trigger an action. The preset value may be a defined steam ratio. A change in vapor ratio can also be used to control the fluid valves. Next, the difference between the actual steam ratio and the predefined steam ratio can be used to determine the need for operation of the at least one fluid valve. You can also use trend analysis.

Similarly, the rate of steam is recorded over a period of time so as to allow predictive control of the steam generation system in an effective manner. At this time, it is effective to record the ratio of steam in all thermostats for a certain period of time.

Similar to the previous discussion of temperature, the same applies to the proportion of steam. Thus, trend analysis can be performed with the collected data and expected steam rates can be calculated in the future.

It is also effective to include all steam ratios determined in all desuperheaters.

If the proportion of steam in the piping before and after at least one desuperheater is known and the mass flow through at least one heat exchanger or evaporator is known, it should be possible to estimate the mass flow through the steam generator. However, it is particularly effective if the proportion of steam is known to all desuperheaters and the mass flow is known to the evaporator and to each desuperheater via distribution piping. Then, by accurately determining the ratio of steam to mass flow in each heat exchanger to superheater, the control system can determine the best settings for the fluid valves, achieving high efficiencies while reducing the risk of thermal damage.

Hereinafter, the accompanying drawings show two different embodiments for implementing the inventive solution in a steam generator.
1 schematically shows a power plant with a steam generator.
Figure 2 schematically shows a steam generator with a first version of a superheater with cooling nozzles.
Figure 3 schematically shows a steam generator with a second version of the superheater with cooling nozzles.

Figure 1 shows schematically a power plant 07 having a gas turbine 09 and a steam turbine 08 and a steam generator 01 as a main part of the invention. The steam generator 01 includes a hot gas path 02 through the steam generator 01 from the hot gas input side to the waste gas output side.

In operation, the gas turbine 09 delivers the hot gas flow to the hot gas input side of the steam generator 01 - while generating electrical energy with the generator. After passing through the hot gas path 02, the formerly hot gas exits the steam generator 01 as waste gas at the waste gas output side with its temperature lowered.

The steam generator (01) further comprises a plurality of heat exchangers (11) disposed at least partially within the hot gas path (02). Within the heat exchanger 11 evaporative fluid (eg water/steam) flows from each fluid input 13 to each fluid output 17 generally in the opposite direction to the hot gases while the hot gases are cooled. It is heated.

Typically, the first heat exchanger along the hot gas path starting at the upstream hot gas input side is the so-called superheater 11A (see Fig. 2). The fluid output line 12 is connected to the steam turbine 02 to allow further generation of electrical energy.

When the power plant 07 starts up or when the power to be supplied by the power plant 07 suddenly increases, the gas turbine 09 increases the output of the hot gas very quickly. This results in a high increase in heat input to the steam inside the superheater (11). Accordingly, high thermal stress is applied to the steam turbine 08 and the pipe inside the steam generator 01 (eg, the fluid output unit 17) and the pipe connected from the steam generator 01 to the steam turbine 08 causes

Next, in a typical steam generator, the fluid flows from one heat exchanger to the next as the temperature increases. However, the share of vapor is not considered in the design of the steam generator.

Referring to FIG. 2 , an example of a steam generator 01 of the present invention comprising a plurality of heat exchangers 11 and desuperheaters 22 is schematically shown.

First, the steam generator 01 includes a casing having a hot gas passage 02 as a main part. The hot gas passage 02 extends from an input opening through which the hot gas 03 flows into the hot gas passage 02 . While passing through the steam generator (01) the gas is cooled and discharged as waste gas (04) on the output side of the hot gas path (02).

The steam generator further includes a plurality of heat exchangers 11A-G. Although the heat exchangers in this example are arranged adjacent to each other, they may be arranged with other elements in between or in a different order.

Here, the heat exchanger close to the hot gas input is the so-called superheater 11A. The superheater 11A includes a superheater fluid input 13A, wherein the superheater fluid output 17A of the superheater 11A delivers a hot steam stream 05 and is connected to a steam turbine 08.

Next to the superheater 11A, a first heat exchanger 11B is disposed. The first heat exchanger 11B similarly comprises a first fluid input 13B and a first fluid output 17B, wherein the first output 17B is connected to the superheater input 13A. .

In the same way, next to the first heat exchanger 11B, a second heat exchanger 11C is disposed. The second heat exchanger 11B similarly includes a second fluid input 13C and a second fluid output 17C, wherein the second output 17C is connected to the first input 13B.

In addition, a third heat exchanger 11D is disposed next to the second heat exchanger 11C. The third heat exchanger 11D similarly includes a third input 13D and a third output 17D, where the third output 17D is connected to the second input 13C.

In addition, a fourth heat exchanger 11E is disposed next to the third heat exchanger 11D. The fourth heat exchanger 11E similarly comprises a fourth input 13E and a fourth output 17E, wherein the fourth output 17E is connected to the third input 13D.

And again, next to the 4th heat exchanger 11E, the 5th heat exchanger 11F is arrange|positioned. The fifth heat exchanger 11F similarly comprises a fifth input 13F and a fifth output 17F, where the fifth output 17F is connected to the fourth input 13E.

An economizer 11G is placed last in the row in the hot gas path 02. The economizer 11G analogously includes an economizer fluid input 13G and an economizer fluid output 17G. Here, the economizer output unit 17G is connected to the fifth input unit 13F.

Each superheater 11A, heat exchangers 11B-11F and economizer 11G is supplied with fluid vapor from hot gas 03 passing through each superheater 11A, heat exchangers 11A-11F and economizer 11G. can transfer heat. Each fluid input 13 is supplied with fluid vapor with a lower temperature and lower vapor ratio. After heat transfer, the fluid stream exits each fluid outlet 17 with a higher temperature and higher vapor ratio.

The economizer input 13G is connected to the cooling fluid supply 24 . This is normal coolant. A fluid supply valve 25 is disposed in the connection from the cooling fluid source 24 to the economizer input 13G to control the flow of cooling fluid through the economizer 11G.

During operation, the cooling fluid from the cooling fluid source 24 uses residual heat in the gas flowing through the hot gas path 02 to the desired temperature close to, but not exceeding, the evaporation temperature of the economizer 11G. ) should be heated. As a result, hot fluid that is not evaporated exits the economizer 11G at the economizer output 17G.

Then, in order to supply sufficient fluid flow to the last heat exchanger, fifth heat exchanger 11F, at the fluid input 13F, in any case, a bypass line is provided from the cooling fluid supply 24 and the economizer output 17G. Connect the connection to the last fluid input (13F). It is clear that an additional fluid bypass valve 27 is required to control the flow of cooling fluid through the bypass.

The main fluid valve 26 is provided at the last fluid input 13F to control the hot fluid flow from the economizer 11G and/or the coolant fluid flow from the bypass to the last heat exchanger, namely the fifth heat exchanger 11F. ) is placed in

Now for a series of heat exchangers, namely fifth, fourth, third, second and first heat exchangers 11F, 11E, 11D, 11C, 11B and superheater 11A, one heat exchanger 11 ) to the next heat exchanger 11B-F and the superheater 11A. At each connection from the fluid output unit 17 to the next fluid input unit 13, desuperheaters 22F, 22D, 22C, and 22B are disposed. To activate the function of the dehumidifiers 22, each desuperheater 22 is connected to a distribution pipe 21 to supply each desuperheater 22 with a flow of non-vaporized fluid.

In this solution, the distribution piping 21 is further connected to the economizer output 17G and via a bypass to the cooling fluid source 24 to provide a "free of vapor" fluid in the distribution piping 21. to secure Placing the main valve 26 at the input of the last heat exchanger 11F can also affect the fluid flow from the economizer 11A to the distribution piping 21 . In addition, the flow of fluid from the cooling fluid supply source 24 through the bypass to the distribution pipe 21 may be controlled by the fluid bypass valve 27 in the bypass passage.

A main desuperheater (22A) is arranged at the superheater outlet (17A) to protect subsequent installations from too rapid a rise in the temperature of the hot steam (05) exiting the steam generator (01). The main desuperheater 22A is also connected to the distribution piping 21, wherein a fluid distribution valve 23A is arranged to control the flow of fluid from the distribution piping 21 to the main desuperheater 22A.

It is possible to control the temperature of the fluid/steam flowing from one heat exchanger 11 to the next heat exchanger 11B-F and superheater 11A, and furthermore, the heat exchanger 11B-F/superheater 11A. Fluid distribution valves 23A, 23B, 23C, 23D, 23E, 23F at each connection from each desuperheater 22B-F to the distribution piping 21, so as to be able to control the proportion of steam at each input of ). need to be placed.

Referring to FIG. 3 , an example of a solution for implementing the advantages of the present invention in more detail in a heat exchanger/superheater 11 is shown. Only the relevant parts of the steam generator 01 are shown here, the hot gas path 02 section and the arrangement of one heat exchanger 11 are shown.

The heat exchangers 11B-11F or superheater 11A include a pipe with a fluid inlet 13, and the fluid inlet 13 is connected to the previous heat exchanger (not shown in this figure). From the fluid input 13 branch off two (illustrative) distribution pipes 14.1 and 14.2. A plurality of heat exchanger tubes 15 are each connected to one of the distribution pipes 14 . Collecting pipes 16.1 and 16.2 are arranged at the other end of the heat exchange tube 15, and the collecting pipe 16 is then connected to the fluid outlet 17.

During operation, cold fluid vapor (12) is supplied to the fluid supply line (13). Steam flows through the distribution pipe 14 to the heat exchange tube 15 where heat is transferred from the hot gas inside the hot gas path 02 to the fluid vapor inside the heat exchange tube 15. The hot fluid vapor is then collected in the collection pipe 16 and delivered to the fluid outlet 17, exiting the heat exchanger/superheater 11 as hot fluid vapor 18.

Superheaters 22.1 and 22.2 are arranged for temperature control of the temperature of the hot steam 18 and the steam ratio. Thus, in this effective solution, desuperheaters 22.1 and 22.2 are arranged in each collecting pipe 16.1 and 16.2. The desuperheater 22 is supplied with a cooling fluid (eg water) from the distribution pipe 21 . Fluid distribution valves 23.1 and 23.2 are arranged to allow control of the cooling fluid in each supply line to the desuperheaters 22.1 and 22.2.

Considering a more extended implementation of the solution described above, a desuperheater may be placed at the end of each heat transfer tube 15 .

In connection with the description of the drawings, reference numeral 11 denotes any one of a superheater 11A or heat exchangers 11B-11F or an economizer 11G (fluid input unit 13 and fluid output unit 17 are the same). Further, reference numeral 22 denotes the desuperheaters 22A-22F or 22.1 or 22.2 (the fluid distribution valve 23 is the same).

01.. Steam generator
02.. Hot gas path
03.. Hot gas
04.. waste gas
05.. Hot steam stream
07.. Power Plant
08.. Steam Turbine
09.. gas turbine
11A.. Superheater
11B-F.. 1-5 heat exchanger
11G.. Economizer
12.. Cold Fluids
13,13A-G.. input
14.1,14.2.. distribution pipe
15.. Heat Exchange Tube
16.1,16.2.. Collecting pipe
17,17A-G.. Outputs
18.. Hot Fluids
21.. Distribution piping
22,22.1,22.2,22A-F.. desuperheater
23,23.1,23.2,23A-F.. Fluid Dispensing Valves
24.. Cooling fluid source
25.. fluid supply valve
26.. Main valve
27.. Fluid bypass valve

Claims (10)

In a steam generator (01) with a hot gas path (02),
- a superheater (11A) with a superheater output (12) for delivering a flow of hot steam (18);
- at least four heat exchangers (11B-11F);
- an economizer (11G),
- a distribution piping (21);
The superheater 11A, the heat exchangers 11B-11F, and the economizer 11G are connected in series, and each has a fluid inlet 13, at least one fluid distribution pipe 14 and the inside of the hot gas path 02. a plurality of heat exchange tubes (15), at least one collecting pipe (16) and a fluid output (17) disposed in the economizer, wherein the input (12G) of the economizer is connected to a source of cooling fluid (24);
An output part 17A of the superheater, a connection part between the superheater 11A and the first heat exchanger 11B, and one heat exchanger 11B-11E among the at least four heat exchangers 11B-11F, respectively. At least one desuperheater 22 is disposed at each connection between the next heat exchangers 11C-11F of
The distribution pipe 21 is connected to the cooling fluid supply source 24 and the output part 17G of the economizer and connected to each desuperheater 22 through each valve 23 Steam generator (1). According to claim 1,
The main valve 26 is disposed at the fluid input 13F of the last heat exchanger 11F of the series of heat exchangers 11B-11F; and/or
A fluid supply valve 25 is disposed at the input 12G of the economizer; and/or
The steam generator (1), wherein the fluid bypass valve (27) is disposed between the cooling fluid supply source (24) and the distribution pipe (21). According to claim 1 or 2,
At least one of the series of superheaters 11A and heat exchangers 11B-11F includes at least two collection pipes 16.1 and 16.2 each having a desuperheater 22.1 and 22.2, in particular each desuperheater 22.1 , 22.2) is a steam generator (1) connected to the distribution pipe (09) through respective fluid distribution valves (23.1, 23.2). A steam generating system having a steam generator (1) according to any one of claims 1 to 3,
a control system capable of controlling the fluid valves 23, 25-27; and
a temperature determination system capable of determining the temperature of at least one of said fluid output (17) and/or fluid input, and/or
and a steam determination system capable of determining a share of vapor before and/or after at least one of the at least one desuperheater (22). According to claim 4,
the temperature determination system is capable of determining the temperature of the fluid output 17 and/or the fluid input, respectively; and/or
wherein the steam determination system is capable of determining the proportion of steam in each of the desuperheaters (22). According to claim 4 or 5,
The control system can control the fluid valves 23, 25-27 individually and in groups and stepwise, in particular the temperature of the fluid outlet 17 and/or the steam in the desuperheater 22. Steam generation system that depends on the ratio. A method for controlling a steam generating system according to any one of claims 4 to 6,
a) determining at least the temperature and/or temperature change at the fluid output 17;
b) compare the temperature/temperature change with a preset value; and
c) A method of controlling at least one of the fluid valves 23, 25-27 according to the comparison result. A method for controlling a steam generating system according to any one of claims 4 to 6,
a) determine at least the proportion of steam in the desuperheater 22;
b) comparing the steam ratio with a preset value; and
c) A method of controlling at least one of the fluid valves 23, 25-27 according to the comparison result. According to claim 7 or 8,
a1) the temperature and/or temperature change is determined at every fluid outlet 17, and/or
a1) Method in which the proportion of the steam in all desuperheaters (22) is determined. The method of claim 8 or 9,
wherein the first and/or second and/or third and/or in particular fourth predetermined proportion of steam is at least 60%, in particular at least 75%, and/or at most 90%, in particular at most 85% of the mass flow .

Images