JP2023541492A - Steam generator with attemperator - Google Patents

Abstract

The invention relates to an advantageous steam generator (01) and steam generation system in which a heat exchanger (11) is arranged in the hot gas path (02). To protect the equipment and increase efficiency, attenuators (22) are arranged at the outlet of at least some of the heat exchangers (11), each of the attenuators (22) being connected to a fluid distribution valve. It is connected to the distribution pipe (21) via (23). [Selection diagram] Figure 2

Description

TECHNICAL FIELD The present invention relates to steam generators and steam generation systems. In particular, the present invention relates to the protection of steam generators and also steam turbines against sudden increases in steam temperature and the efficient heat transfer from hot gases to the evaporative medium.

Power plants often combine gas turbines with steam turbines to most efficiently produce electrical energy. Typically, a steam generator is used to convert hot gas from a gas turbine into hot steam for a steam turbine.

Therefore, a typical steam generator first includes a hot gas passage from the hot gas inlet to the exhaust gas outlet. A plurality of heat exchangers are arranged inside the hot gas duct, starting from an economizer on the exhaust gas outlet side, via a series of further heat exchangers, to a superheater on the hot gas inlet side. The temperature of the fluid flowing through the heat exchanger increases with each heat exchanger, cold water is supplied to the economizer, and hot steam exits the superheater.

Gas turbines rapidly increase the temperature of hot gases exiting the gas turbine to enable a rapid response to electrical energy demands. Without protection measures, this rapid temperature change creates a risk of excessive thermal stresses, especially in steam turbines.

Therefore, a common solution is to place attemperators in the connecting piping from the steam generator to the steam turbine. Attemperators are used to inject water into the hot steam after the superheater. This reduces the temperature of the high temperature steam sent to the steam turbine.

Although protection of steam turbines through the use of attemperators is well established, there is no protection of the steam generator itself upstream (along the steam flow) of the attemperator. The highest temperature or greatest temperature change occurs inside the outlet of the superheater near the hot gas inlet in the hot gas path. This further creates high thermal stresses in the piping from the superheater to at least the location of the attemperator and increases the size of the equipment used.

A further solution is therefore known from the prior art, in which an attemperator is arranged between the penultimate heat exchanger and the superheater as the last heat exchanger. Compared to the previously described solutions, the stresses in the superheater itself and thus in the piping at the outlet of the superheater are reduced.

However, the solution of placing an attemperator before the superheater has the disadvantage of poor controllability of the temperature of the hot steam at the outlet of the superheater. As a result, efficiency may decrease when the power plant starts up or when the power generation output suddenly increases.

A further disadvantage of common systems is that the control of the attemperator is very sensitive. To prevent overshoot due to sensitive control of steam temperature by opening and closing valves in the chilled water line to the attemperator, it is generally necessary to compare the actual temperature/temperature change during operation, especially at turbine start-up, with the allowable temperature. It is necessary to maintain a further difference between the temperature/temperature change.

As a result, placing an attemperator in front of a superheater does not improve the required difference between the actual temperature/temperature change and the allowed temperature/temperature change during operation.

It is also known from the prior art that once-through steam generators can have a slow response to temperature changes due to the long transit time of the feed water through all the heat exchangers towards the outlet of the superheater.

Therefore, the object of the present invention is to make it possible to adjust the temperature of high-temperature steam well and quickly, and to protect the piping of the superheater on the outlet side and the piping to the steam turbine from rapid temperature changes. That's true.

This object is solved by a steam generator according to claim 1 . A steam generation system enabling its operation is described in claim 4. An inventive method for operating a steam generation system is defined in claim 7. Advantageous solutions are described in the further claims.

A common type of steam generator has a casing through which the hot gas passage passes from the hot gas inlet to the exhaust gas outlet. The steam generator includes a plurality of heat exchangers located at least partially within the hot gas path.

A superheater as one of the plurality of heat exchangers is arranged near the hot gas inlet. The superheater includes a superheater outlet as a connection to further equipment, for example a steam turbine, and delivers a stream of hot steam. The superheater further includes a superheater inlet.

Furthermore, a first heat exchanger is arranged within the hot gas passage. The first heat exchanger also includes a first outlet section and a first inlet section. Here, the first outlet is connected to the superheater inlet.

Next, a second heat exchanger is arranged within the hot gas passage. The second heat exchanger similarly includes a second outlet section and a second inlet section. Here, the second outlet section is connected to the first inlet section.

Next, a third heat exchanger is arranged within the hot gas passage. The third heat exchanger similarly includes a third outlet section and a third inlet section. Here, the third outlet section is connected to the second inlet section.

Next, a fourth heat exchanger is arranged within the hot gas passage. The fourth heat exchanger similarly includes a fourth outlet section and a fourth inlet section. Here, the fourth outlet is connected to the third inlet.

In further embodiments, it is also possible to arrange a fifth heat exchanger in series next to the fourth heat exchanger, or alternatively it is also possible to arrange further heat exchangers in series, so that further heat exchangers can be arranged in series. The exchanger includes a fluid inlet and a fluid outlet, each connected to a series of heat exchangers.

An economizer is placed at the end of the hot gas passage. The economizer also includes an economizer outlet and an economizer inlet. Here, the economizer outlet is connected to the fluid inlet of the last heat exchanger. The economizer inlet is connected to a source of cryogenic fluid. Common solutions use water as the fluid, but it is also possible to use other fluids that can be evaporated.

The numbering of heat exchangers and associated elements is done in this context opposite to the direction of flow through the heat exchanger. Therefore, the heat exchanger connected to the superheater is named the first heat exchanger, and the heat exchanger connected to the economizer is named the last heat exchanger.

It should be noted that the superheater, heat exchanger and economizer do not necessarily have to be placed next to each other and/or in this order in the hot gas path. It is also possible to place other functional parts or other heat exchangers in the hot gas path that are not connected along the series of heat exchangers according to the general solution or to heat exchangers and heat exchangers in the general solution. It is also possible to arrange it between the exchanger and the exchanger.

It is further noted that the superheater, heat exchanger and economizer do not necessarily have to be directly connected to each other. It is also possible to install further devices, for example other heat exchangers or containers, between the superheater and the heat exchanger, between the heat exchanger and the heat exchanger and/or between the heat exchanger and the economizer according to the general solution. It is also possible to place it between the miser and the miser. However, in a preferred solution, the superheater is connected directly to the first heat exchanger until the last heat exchanger in the series is connected to the economizer, and the first heat exchanger is connected directly to the second heat exchanger. directly connected to the heat exchanger, and the others similarly.

Each of the superheater, heat exchanger, and economizer includes a fluid inlet connected to a further heat exchanger or another part of the steam generator. During operation, a cool fluid, such as water and/or steam, is supplied to the fluid inlet. The fluid inlet is connected to one or more distribution pipes to distribute the fluid flow to different pipes. Each of the superheater, heat exchanger, and economizer further includes a plurality of heat exchange tubes each connected to one of the respective distribution pipes. The plurality of heat exchange tubes are arranged at least partially, in particular completely, in the hot gas path. During operation, as a flow of hot gas passes through the heat exchanger along a hot gas path, heat is transferred from the hot gas to a fluid, such as water/steam, in the heat exchange tubes. Each of the plurality of heat exchange tubes is connected to a collecting pipe, and each of the superheater, heat exchanger, and economizer includes one or more collecting pipes for collecting hot fluid from the heat exchange tubes. The collecting pipe is connected to a fluid outlet which serves as a connection to a further heat exchanger or other equipment, for example a steam turbine.

The steam generator further includes distribution piping for distributing certain fluids.

A first attenuator is disposed in a pipe extending from a first outlet of the first heat exchanger to an inlet of the superheater. The first attemperator includes a connection to the distribution piping, and the connection to the distribution piping includes a first fluid distribution valve for controlling flow from the distribution piping to the first attemperator. Placed.

In order to improve the stability of the control of the steam generator for the solution of the invention, an additional attenuator is provided in the heat exchanger.

Therefore, a second desuperheater is disposed in the pipe leading from the second outlet of the second heat exchanger to the first inlet of the first heat exchanger. The second attemperator also includes a connection to the distribution piping, and the connection to the distribution piping is disposed with a second fluid distribution valve for controlling flow from the distribution piping to the second attemperator. be done.

Furthermore, a third desuperheater is disposed within the piping from the third outlet to the second inlet. The third attemperator also includes a connection to the distribution piping, and the connection to the distribution piping is disposed with a third fluid distribution valve for controlling flow from the distribution piping to the third attemperator. be done.

Next, a fourth desuperheater is arranged in the piping from the fourth output part to the third input part. The fourth attemperator also includes a connection to the distribution piping, and the connection to the distribution piping is disposed with a fourth fluid distribution valve for controlling flow from the distribution piping to the fourth attemperator. be done.

If further heat exchangers are arranged between the fourth heat exchanger and the economizer, each connection from one heat exchanger to the next in the series of heat exchangers has an additional superheat It is possible to arrange a reducer. In this embodiment it is further advantageous to arrange a separate fluid distribution valve at the connection from the further attemperator to the distribution pipe.

The solution of the invention requires supplying fluid to the attemperator. The distribution pipe is therefore connected to the economizer outlet. Further connections from the distribution piping to a source of cryogenic fluid are available so that the temperature and flow rate through the distribution piping can be controlled. This allows warm but non-evaporated fluid, such as hot water, to be supplied to different attemperators to enable beneficial control of temperature while achieving advantageous efficiencies.

Each of the attemperators includes one or more fluid nozzles that direct a cooling fluid, e.g., water, to the steam flowing through the attenuator, e.g., from one heat exchanger to the next in a series of heat exchangers. the connection to the heater or superheater. The fluid nozzle itself is connected to the distribution piping as a cooling fluid supply for the attemperator. The flow of cooling fluid from the distribution piping to the fluid nozzles can be controlled by using respective fluid distribution valves.

As a result, adding extra fluid to the evaporation zone increases steam production, reduces travel time, and improves response speed. Also, the attemperator fluid is added in a boiling environment and therefore does not increase exergy losses since the fluid temperature is substantially constant.

In a preferred embodiment, a main valve is arranged between the inlet of the last heat exchanger before the economizer and the economizer outlet. This allows the flow of fluid to the last heat exchanger to be controlled.

In a further particular solution, the fluid supply valve is arranged at the economizer inlet or at the economizer outlet. This allows the flow of fluid through the economizer to be controlled.

A bypass to the economizer should be used when fluid flow through the economizer needs to be blocked or when fluid flow through the economizer is insufficient to supply the last heat exchanger and distribution piping. I can do it. In order to be able to control the flow through the bypass, in an advantageous solution a fluid bypass valve is arranged in the connection from the distribution pipe to the source of cryogenic fluid.

In order to be able to advantageously control the steam temperature at the outlet of the superheater, in a preferred solution the main attemperator is arranged at the outlet of the superheater. The attemperator is also connected to the distribution piping and an attemperator distribution valve is disposed within the connection. This allows the steam temperature to be precisely controlled, especially during startup of the steam turbine.

In order to protect the piping between the heat exchangers, in particular the piping at the superheater outlet, it is advantageous to arrange an attemperator in at least two collecting pipes of the heat exchanger and/or preferably in the superheater. It is. In particular, it is advantageous to arrange an attemperator in the existing collecting pipes of each heat exchanger and superheater.

Placing an attemperator in the collecting pipe allows the temperature of the hot fluid, e.g. steam, at the outlet of the heat exchanger and superheater to be advantageously controlled with rapid response to changes in heat input. be. Furthermore, the fluid outlet line can be protected against sudden temperature changes. As a result, a particularly long service life can be expected and, in the best case, restrictions on the start-up of the steam generator can be dispensed with.

The solution of providing an attemperator in the collecting pipe is the best compromise between the effort of implementing a cooling solution and protection against thermal stresses.

Now, each of the attemperators must be connected to the distribution piping, all attemperators of one heat exchanger and superheater must be connected to one fluid distribution valve, and one heat exchanger and superheater must be connected to one fluid distribution valve. It is possible to control the flow of cooling fluid to all of the attemperators simultaneously.

In contrast to the first embodiment above, it is advantageous if more than one fluid distribution valve is used. In this case, each of the fluid distribution valves is used to control the flow of cooling fluid to at least one attemperator. The second method makes it possible to control the temperature of the steam at each outlet of the collecting pipe separately.

In the following, "fluid valve" refers to the aforementioned valve actually implemented in the steam generation system, i.e.
- Main valve at the fluid inlet of the last heat exchanger
- a fluid supply valve at the economizer inlet; - a fluid bypass valve at the upstream end of the distribution piping; - one of the fluid distribution valves located between each attemperator and the distribution piping; "fluid valves" means at least two of those valves.

One advantage of using multiple fluid valves is that simple on-off valves can be used, where the number of fluid valves opened depends on the temperature of the hot steam during operation. Change.

The maximum temperature within the heat exchanger can be expected upstream of the hot gas inlet (with respect to the flow of hot gas through the steam generator). The arrangement of at least two attenuators in the collecting pipe is therefore advantageous when used in a superheater, especially when the attenuators are arranged at the hot gas inlet.

The inventive steam generator enables an inventive steam generation system comprising an inventive steam generator according to the above description. Here, the steam generation system needs to include a control system. A control system is connected to the plurality of fluid valves to control the open position of each fluid valve.

In order to enable favorable operation of the steam generation system with the control system, it would be advantageous if different fluid valves of the steam generator could be controlled separately, in particular for different heat exchangers and superheaters.

Furthermore, it would be advantageous if different fluid valves of the plurality of fluid valves could be controlled in groups simultaneously and independently of each other.

To enable optimized control, the control system configures at least some of the fluid valves such that the strength of fluid flow from the distribution piping to the respective attemperator corresponds to the need. It would be even more advantageous if it could be controlled in stages.

Preferably, two types of information regarding the status of the steam generator can be used to control the steam generation system.

In a first embodiment, the steam generation system further includes a temperature measurement system that includes a temperature sensor. The temperature measurement system may use a temperature sensor to measure at least the temperature of the hot steam exiting one of the heat exchanger and the superheater, or the temperature of the piping at the fluid outlet.

The temperature measurement system must be able to measure the actual temperature of the fluid at the fluid outlet of the heat exchanger and superheater. For example, a temperature sensor may be utilized within the fluid outlet. However, instead it may be sufficient to measure the temperature at the fluid outlet, ie the temperature of the tube itself. The temperature of the hot steam within the fluid outlet could then also be calculated.

In order to be able to improve the control of the different fluid valves, preferred embodiments include at least one additional temperature sensor. This can be by providing, in addition to the first temperature sensor, a second temperature sensor of the second attemperator, such as the second outlet of the second heat exchanger. The temperature of the steam and/or piping before or after can be measured.

Preferably, the third temperature sensor is capable of measuring the temperature of the steam and/or piping before or after the third attemperator.

The same applies to further heat exchangers and superheaters, preferably using further temperature sensors to analyze the temperature in other attemperators.

Using a temperature measurement system that can measure several temperatures in different attemperators allows the control system to independently control different fluid valves in response to different temperatures in each attemperator.

A second embodiment of the steam generation system of the invention requires a steam measurement system. Here, the vapor measurement system must be capable of measuring at least one share of vapor of the fluid in the piping before and/or after one of the plurality of attemperators. .

First of all, nothing is more appropriate if the amount of vapor or liquid water in the fluid stream is used as the vapor fraction. It is then also possible to measure the percentage by volume or the percentage by mass.

However, it is preferred to define the amount of steam in the mass flow rate as the steam fraction.

Knowing the mass flow from the distribution piping to the first attemperator and the mass flow through the attemperator, the steam fraction on the other side of the attemperator can be calculated (if the steam fraction measurement section If it is located upstream, it can also be found downstream, and vice versa).

As well as measuring the temperature, it would be advantageous if the steam measurement system could measure the steam at the further attemperator.

By using a steam measurement system that can measure the steam fraction in different attemperators, the control system can independently control different fluid valves depending on the steam fraction in each attemperator.

In a third embodiment, the steam generation system combines the first embodiment with a temperature measurement system and the second embodiment with a steam measurement system. wherein the steam generation system is configured to operate a plurality of fluid valves in response to temperature changes in respective temperatures measured in the plurality of attemperators and in response to steam fractions analyzed in the plurality of attemperators by a control system. allows you to control.

New steam generation systems such as those described above enable new and inventive methods for controlling steam generation systems. Different implementations are possible depending on the measurement system used.

In steam generation systems with a temperature measurement system, in a first step it is necessary to measure the actual temperature at the fluid outlet of the heat exchanger. As already explained, this may be the temperature of the pipe itself or the temperature of the fluid within the pipe. In the first case it would be possible to estimate the temperature of the fluid, and in the second case it would be possible to estimate the temperature of the pipe.

Furthermore, it is also possible to measure actual temperature changes.

In a second step it is necessary to compare the actual temperature with a predetermined value.

In a third step, at least one fluid valve is controlled depending on the comparison of the actual temperature/temperature change with a predetermined value. Here, it is at least possible to open and close the at least one fluid valve.

Preferably, it is possible to open the fluid valve in stages and/or to open and close a plurality of fluid valves.

The control system compares the measured actual temperature or temperature change with a predetermined value, and depending on the result, mainly when the actual temperature or actual temperature change exceeds the predetermined value. , the control system can control at least one fluid valve of the plurality of fluid valves.

In a first obvious solution, the predetermined value may be the maximum allowable temperature. Opening the fluid distribution valve when the actual temperature exceeds the maximum allowable temperature introduces cooling fluid into the steam to reduce the temperature of the fluid and piping.

The introduction of cooling fluids, e.g. water, into the fluid (steam, hot water) at the outlet of heat exchangers and superheaters is only possible under certain circumstances, especially when the temperature is too high or there is a risk that the temperature rises too quickly. It may be necessary only in some cases.

In further embodiments, the maximum temperature change can be used as a predetermined value. At least one fluid distribution valve is opened if the main temperature increase exceeds the maximum temperature change. This suppresses and even stops further temperature increases in the steam and pipes.

Both limits can also be used in combination to analyze unacceptable temperatures or the risk of reaching unacceptable temperatures.

Using input from the temperature measurement system, the control system needs to be able to calculate the necessary responses to protect the steam generation system and subsequent equipment from overheating or rising heat too quickly. Therefore, a control system must be connected to the fluid valve. If the predetermined value is exceeded, the control system can open one or more of the fluid valves accordingly.

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

Furthermore, it is possible to define a predetermined value as the maximum temperature depending on the actual temperature change. Defining the maximum temperature in advance according to the temperature change may mean, for example, defining the maximum temperature to be higher when the temperature change is small, and to be lower when the temperature change is large.

Furthermore, it is also possible to use the maximum temperature change depending on the actual temperature as the predetermined value. In this case, for example, lower temperatures may allow larger maximum temperature changes and higher temperatures may allow smaller maximum temperature changes. As a result, faster temperature changes can be tolerated in non-hazardous temperature ranges due to faster increases in power output, and smaller temperature changes can be protectively applied when temperatures reach the limits of the materials involved. Ru.

In a preferred case, the temperature of the fluid at the fluid outlet and/or the temperature of the fluid outlet triggers a control system if it exceeds a predetermined value, in order to protect the equipment, and also Associated with opening a valve.

It is clear that when using the maximum temperature change as the predetermined value, the actual temperature change is used, and not only the actual temperature.

In addition to one fixed predetermined value, it is also possible to use a characteristic curve as predetermined value instead. The characteristic curve can be a predetermined maximum temperature that changes in value as the temperature changes. In this case, the characteristic curve is predefined. As a result, the control system will use a characteristic curve that yields different predetermined values depending on the actual temperature change.

Conversely, it is also possible to define a characteristic curve with a predetermined maximum temperature change whose value changes depending on the temperature. This provides a predetermined value for comparison for a control system with a maximum temperature change depending on the actual temperature.

In order to enable further advantageous control of the steam generation system, the comparison of the temperature/temperature change with a predetermined value, as well as the actual temperature and the difference between the actual temperature change and the permissible process conditions, is Further consideration. It is therefore advantageous that the difference between the actual temperature and actual temperature change and a predetermined value is calculated.

In a further advantageous step, it is possible to perform a trend analysis on the actual temperatures. Therefore, it is necessary to record the actual temperature over a period of time. Using this data of past and current temperatures, predicted temperatures can be calculated. This makes it possible not only to compare the actual temperature with a predetermined value, but also to compare with a predicted temperature, and further, to compare the predicted temperature with a predetermined value. It is also possible to calculate the difference. This information can also be used to further predictably drive the fluid valves.

In an advantageous method, a steam generation system is used in which the temperature/temperature change at all fluid outlets in all heat exchangers and superheaters can be measured. This allows you to compare all actual temperatures/temperature changes to their respective predetermined values and control each fluid valve depending on each comparison, as well as each non-attemperature comparison. It also becomes possible to control fluid valves.

In a further step, the fluid distribution valve is opened depending on the difference between the current situation and an acceptable situation. It is therefore further advantageous to open some of the fluid distribution valves of the plurality of fluid distribution valves depending on the calculated difference, if that difference is available. Here, the "fluid valves to be opened" can be selected according to further rules.

Steam generator protection may be improved and/or efficiency may be increased if the fluid valve is not only on and off. In an advantageous solution, the at least one fluid distribution valve can open stepwise, for example depending on the difference between the actual temperature or temperature change and a predetermined value. Similarly, the fluid valves to be operated can also be selected according to further rules.

Of course, it is also possible to implement a control system that has both options, opening multiple fluid valves independently and in stages.

A preferred solution with an additional temperature sensor allows a more advantageous way to operate the steam generator system. In this case, in a first step it is necessary to measure at least one or more further temperatures. This is the main temperature of the main temperature sensor at the fluid outlet of the superheater, or the first temperature of the first temperature sensor at the first fluid outlet of the first heat exchanger, or the first temperature of the first temperature sensor at the first fluid outlet of the first heat exchanger. a second temperature of a second temperature sensor at a second fluid outlet of the second temperature sensor, and so on. Additionally, a main temperature change, a first temperature change, a second temperature change (and so on) may be measured.

In this example with multiple actual temperatures, in the next step the main temperature/main temperature change, first temperature/first temperature change, second temperature/second temperature change (and so on) are respectively Must be compared to a primary predetermined value, a first predetermined value, a second predetermined value, a third predetermined value, a fourth predetermined value (etc.) There is.

By calculating the difference, in a next step the respective fluid distribution valve, and preferably also the other fluid valves, can be controlled in a stepwise manner depending on the determined difference.

It is clear that in a simple solution all fluid valves are controlled (opened and closed) at the same time. However, in a preferred solution, the control system can control different fluid valves individually. In this case, the main fluid valve, the first fluid distribution valve, and the second fluid distribution valve (and any other available valves) are individually controlled in response to exceeding their respective predetermined values. It would be advantageous if you could do so.

In order to enable predictive control of the steam generation system, in an advantageous method the temperature and temperature changes are recorded over a period of time. In this case, it is advantageous to record the temperature of some or all of all attemperators over a period of time.

This collected data can be used to perform trend analysis and calculate expected future temperatures and expected future temperature changes, respectively.

The next step is to measure not only the actual temperature, but also the actual temperature change. From now on, it is possible to compare the currently measured actual temperature and temperature changes with the previously predicted values.

It is clear that similar comparisons can also be made for measured temperatures/temperature changes.

In a further advantageous control method, it is possible to calculate the difference between each last actual temperature, each temperature change, and the corresponding previously determined predicted value.

The predicted value and the corresponding predetermined value can then be compared.

In a further advantageous control method, it is possible to calculate the difference between the predicted value and a corresponding predetermined value.

As a result, depending on the comparison or, preferably, depending on the calculated difference, several fluid valves are opened and/or a plurality of fluid valves are opened in stages. This enables predictive control of steam temperature.

The new steam generation system as described above also enables a second inventive method of controlling the steam generation system. Therefore, again a steam generation system according to one of the previous descriptions is required. This must include a vapor measurement system. This second method includes several steps.

In a steam generation system that includes a steam measurement system, it is necessary in a first step to measure the actual steam fraction of the fluid flowing through the piping before or after the attemperator.

Regardless of whether the steam fraction is measured before or after the attemperator, knowledge of the mass flow rate from the distribution piping to this attemperator is used to determine the steam fraction on the other side of the attemperator. could be calculated with sufficient accuracy.

As with the case of using measured temperatures, it is necessary to compare the actual steam rate with a predetermined value.

In a next step, the control system can control at least one fluid valve in response to this comparison.

The predetermined value may be the maximum allowable steam proportion (maximum allowable steam proportion) or the minimum allowable vapor proportion (minimum allowable steam proportion). Alternatively, the predetermined value may be the target steam rate. If a maximum allowed steam rate is set, the fluid distribution valve may be opened (further opened) when the actual steam rate exceeds the maximum allowed steam rate. On the other hand, if the steam rate is lower than a predetermined minimum allowable steam rate, the fluid distribution valve may be closed (further closed).

It is advantageous to determine the difference between the actual steam proportion and a predetermined value.

In particular, once the difference is known, at least one fluid distribution valve can be opened depending on the determined difference between the actual steam fraction and the respective predetermined value, e.g. the target steam fraction. It's advantageous.

Preferably, the steam fraction in the further attenuator can be measured. It would be particularly advantageous if the steam fraction in all attemperators could be measured.

Regarding the control of the fluid valves, the same advantageous solutions apply as with the method using the temperature measuring system. It would therefore be advantageous if the fluid valves could be opened in stages and/or in groups.

It is further advantageous to set a predetermined value for the steam fraction in each heat exchanger in order to adequately protect the steam generator and the subsequent equipment, and also to bring the steam generator to the highest available efficiency. It is.

where, excluding the superheater, if the predetermined values indicate a steam fraction of at least 60% at the outlet of the respective heat exchanger (measured at a position before the next attemperator), It's advantageous. It is particularly advantageous if the steam proportion is at least 75%.

On the other hand, it is advantageous if the steam fraction at the outlet of the heat exchanger other than the superheater does not reach 100%. Therefore, it is advantageous for the predetermined value to be a steam fraction of 90% or less. It is particularly advantageous if the predetermined value is a steam fraction of 85% or less.

It would be beneficial to apply these advantageous features to a method for controlling a steam generation system including a steam measurement system, as well as a method for controlling a steam generation system including a temperature measurement system.

Therefore, it is advantageous to measure the steam fraction in several attemperators. It is particularly advantageous to measure the steam fraction in all attemperators.

It is then advantageous to control some or all fluid valves in a stepwise manner, in particular depending on the steam proportion in some or all attemperators.

Similarly, various predetermined values may be used to trigger certain actions. The predetermined value may be a defined steam percentage. It is also possible to use changes in steam proportion to control fluid valves. The difference between the actual steam rate and the predefined steam rate can then be used to determine whether at least one fluid valve needs to be operated. Trend analysis may also be used.

In order to enable predictive control of the steam generation system, in an advantageous method the steam proportion is likewise recorded over a period of time. It is advantageous here to record the steam rate in all attemperators over a period of time.

As previously explained for temperature, the same advantageously applies for steam proportion. Accordingly, trend analysis can be performed using the data collected and future expected steam rates can be calculated.

It is also advantageous to include the measured steam fraction in all attemperators.

Estimate the mass flow rate through the steam generator if the steam fraction in the piping before or after at least one attemperator is known and the mass flow rate through at least one heat exchanger or evaporator is known. It would be possible. However, it is particularly advantageous that the steam fraction is known in all attemperators, the mass flow rate to the evaporator is known, and the mass flow rate through the distribution piping to each of the attenuators is known. It is. And accurate measurement of mass flow rate and steam fraction in each heat exchanger and superheater allows the control system to find the optimal fluid valves to reduce the risk of thermal damage and achieve high efficiency. It may be possible to determine the settings.

The figures below show two different examples for implementing the inventive solution in a steam generator.

1 is a schematic diagram of a power plant with a steam generator; FIG. 1 is a schematic diagram of a steam generator with a superheater of a first version with cooling nozzles; FIG. 2 is a schematic diagram of a steam generator with a second version superheater with cooling nozzles; FIG.

FIG. 1 is a diagram schematically showing a power generation plant 07, which includes a gas turbine 09, a steam turbine 08, and a steam generator 01 as a main part of the present invention. The steam generator 01 includes a high-temperature gas passage 02, and the high-pressure gas passage 02 passes through the steam generator 01 from the high-temperature gas inlet side to the exhaust gas outlet side.

In operation, the gas turbine 09 supplies a hot gas flow to the hot gas input side of the steam generator 01 while allowing the generation of electrical energy by the generator. After passing through the high-temperature gas passage 02, the high-temperature gas exits the steam generator 01 as exhaust gas on the exhaust gas output side in a lowered temperature state.

The steam generator 01 further includes a plurality of heat exchangers 11, and these heat exchangers 11 are at least partially arranged within the hot gas passage 02. Within the heat exchanger 11, an evaporative fluid, e.g. water/steam, flows from a respective fluid inlet 13 to a respective fluid outlet 17 in a generally opposite direction to the hot gas and is heated, and the hot gas is cooled. Ru.

Typically, the first heat exchanger along the hot gas path starting from the upstream hot gas inlet side is a so-called superheater 11A (see also FIG. 2). Fluid outlet line 12 is connected to steam turbine 02 so that further electrical energy can be generated.

Upon start-up of the power plant 07 or with a sudden increase in the power that needs to be supplied by the power plant 07, the gas turbine 09 increases the outflow of hot gas very quickly. This greatly increases the heat input to the steam within the superheater 11. This results in high thermal stresses in the steam turbine 08 and also in the piping in the steam generator 01, for example the fluid outlet section 17, and also in the piping from the steam generator 01 to the steam turbine 08.

In a typical steam generator, the fluid then flows from one heat exchanger to the next with increasing temperature. However, in the design of steam generators, steam fraction is not considered.

An example of a steam generator 01 according to the invention having a plurality of heat exchangers 11 and attemperators 22 is shown schematically in FIG.

First, the steam generator 01 includes a casing having a high temperature gas passage 02 as a main part. A hot gas passage 02 extends from the inlet opening, and hot gas 03 is introduced into the hot gas passage 02 from the inlet opening. The gas is cooled while passing through the steam generator 01 and exits the hot gas passage 02 on the output side as exhaust gas 04.

The steam generator further includes a plurality of heat exchangers 11A-G. Although they are placed next to each other in this example, they can also be sandwiched with other elements or placed in other orders.

Here, the heat exchanger near the hot gas inlet is a so-called superheater 11A. Superheater 11A includes a superheater fluid inlet 13A, and a superheater fluid outlet 17A of superheater 11A delivers a flow of hot steam 05 and is connected to steam turbine 08.

A first heat exchanger 11B is arranged next to the superheater 11A. This first heat exchanger 11B likewise includes a first fluid inlet section 13B and a first fluid outlet section 17B, and the first outlet section 17B is connected to the superheater inlet section 13A.

Similarly, a second heat exchanger 11C is arranged next to the first heat exchanger 11B. This first heat exchanger 11B similarly includes a second fluid input section 13C and a second fluid output section 17C, and the second output section 17C is connected to the first input section 13B.

Further, a third heat exchanger 11D is arranged next to the second heat exchanger 11C. This third heat exchanger 11D similarly includes a third inlet section 13D and a third outlet section 17D, and the third outlet section 17D2 is connected to the second input section 13C.

A fourth heat exchanger 11E is arranged next to the third heat exchanger 11D. This fourth heat exchanger 11E similarly includes a fourth inlet section 13E and a fourth outlet section 17E, and the fourth outlet section 17E is connected to the third inlet section 13D.

Further, a fifth heat exchanger 11F is arranged next to the fourth heat exchanger 11E. This fifth heat exchanger 11F similarly includes a fifth inlet section 13F and a fifth outlet section 17F, and the fifth output section 17F is connected to the fourth input section 13E.

The economizer 11G is placed at the end of the row in the hot gas passage 02. The economizer 11G also includes an economizer fluid inlet 13G and an economizer fluid outlet 17G. Here, the economizer outlet section 17G is connected to the fifth inlet section 13F.

Each of superheater 11A, heat exchangers 11B-11F, and economizer 11G transfers heat from hot gas 03 to fluid vapor passing through each of superheater 11A, heat exchangers 11A-11F, and economizer 11G. can do. Each fluid inlet 13 is supplied with fluid vapor having a low temperature and a low vapor percentage. After the heat has been transferred, the fluid streams exit their respective fluid outlet sections 17 at higher temperatures and higher vapor rates.

The economizer inlet 13G is connected to a cryogenic fluid supply source 24. The cryogenic fluid is ordinary low temperature water (chilled water). A fluid supply valve 25 is located at the connection from the cryogenic fluid source 24 to the economizer inlet 13G to control the flow of cryogenic fluid through the economizer 11G.

During operation, the cryogenic fluid from the cryogenic fluid source 24 is pumped in the economizer 11G to a preferred temperature near, but not exceeding, the vaporization temperature using the remaining heat of the gas flowing through the hot gas passage 02. heated. As a result, hot but unevaporated fluid exits economizer 11G at economizer outlet 17G.

In order to provide the next and last heat exchanger, i.e. the fifth heat exchanger 11F, with sufficient fluid flow in all situations at the fluid inlet section 13F of the last heat exchanger, a bypass line is provided for the cold fluid flow. The supply source 24 is connected to a connection from the economizer outlet 17G to the last fluid inlet 13F. It is clear that a fluid bypass valve 27 is additionally required to control the flow of cryogenic fluid through the bypass.

Main fluid valve 26 so as to be able to control the flow of hot fluid from economizer 11G and/or the flow of cold fluid from the bypass to the last heat exchanger, i.e., fifth heat exchanger 11F. is arranged at the last fluid inlet section 13F.

In a series of heat exchangers, i.e. fifth, fourth, third, second, first heat exchangers 11F, 11E, 11D, 11C, 11B, and even superheater 11A, the fluid of a certain heat exchanger 11 At the connection from the outlet section 17 to the next heat exchanger 11B-F and the fluid inlet section 13 of the superheater 11A, attenuators 22F, 22D, 22C, 22B are arranged. To enable each attenuator 22 to function, each attenuator 22 is connected to a distribution piping 21 for supplying a flow of unevaporated fluid to each attenuator 22 .

In this solution, the distribution pipe 21 is further connected to the economizer outlet 17G and via a bypass to a source 24 of cryogenic fluid, in order to ensure that the fluid in the distribution pipe 21 is "steam-free". There is. Placing the main valve 26 at the inlet of the last heat exchanger 11F also affects the flow of fluid from the economizer 11A to the distribution pipe 21. Additionally, fluid flow from the source of cryogenic fluid 24 to the distribution piping 21 through the bypass is controlled by a fluid bypass valve 27 in the bypass.

A main attenuator 22A is arranged at the superheater outlet 17A so that subsequent equipment can be protected from a sudden rise in the temperature of the hot steam 05 exiting the steam generator 01. The attemperator 22A is also connected to the distribution piping 21, and a fluid distribution valve 23A is arranged to control the flow of fluid from the distribution piping 21 to the main attemperator 22A.

The temperature of the fluid/steam flowing from one heat exchanger 11 to the next heat exchanger 11B-F and superheater 11A is controlled, and the steam ratio at the inlet of each heat exchanger 11B-F/superheater 11A is controlled. A fluid distribution valve 23A, 23B, 23C, 23D, 23E, 23F must be placed at each connection from each attemperator 22B-F to distribution piping 21 so that it can be controlled.

An exemplary solution for advantageously implementing the invention in a heat exchanger/superheater 11 is shown in more detail in FIG. Here, only the relevant parts of the steam generator 01 are depicted together with the hot gas passages 02 and one heat exchanger 11 arrangement of that part.

Heat exchangers 11B-11F or superheater 11A include piping having a fluid inlet 13, which is connected to the aforementioned heat exchanger (not shown in this figure). Two (exemplary) distribution pipes 14.1 and 14.2 branch off from the fluid inlet 13. 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 18, which collecting pipes 16 are in turn connected to the fluid outlet 17.

During operation, cool fluid vapor 12 is supplied to fluid supply line 13 . This steam flows into the heat exchange tube 15 through the distribution pipe 14, and heat is transferred from the hot gas in the hot gas passage 02 to the fluid vapor in the heat exchange tube 15. The hot fluid vapor is then collected in collecting pipe 16 and directed to fluid outlet section 17 and exits heat exchanger/superheater 11 as hot fluid vapor 18 .

Attemperators 22.1, 22.2 are arranged so that the temperature and steam proportion of hot steam 18 can be controlled. In this advantageous solution, therefore, attemperators 22.1 and 22.2 are arranged in each of the collecting pipes 16.1 and 16.2. The attemperator 22 is supplied with a cooling fluid, such as water, from the distribution pipe 21 . Fluid distribution valves 23.1, 23.2 are arranged to allow control of the cooling fluid in each supply line to the attemperators 22.1, 22.2.

It should be noted that in broadly implementing the above solution, it is possible to place an attemperator at the end of each heat transfer tube 15. Regarding the explanation of the drawings, it should be noted that 11 represents any one of the superheater 11A, the heat exchangers 11B-11F, and the economizer 11G (the same applies to the fluid inlet section 13 and the fluid outlet section 17). Furthermore, 22 represents any attemperator 22A-22B or 22.1 or 22.2 (as well as fluid distribution valve 23).

01 Steam generator 02 High temperature gas passage 03 High temperature gas 04 Exhaust gas 05 High temperature steam outlet 07 Power plant 08 Steam turbine 09 Gas turbine 11A Superheater 11B to F 1st to 5th heat exchangers 11G Economizer 12 Low temperature fluid 13, 13A-G Inlet section 14.1, 14.2 Distribution pipe 15 Heat exchange tube 16.1, 16.2 Collecting pipe 17, 17A-G Outlet section 18 High-temperature fluid 21 Distribution pipe 22, 22.1, 22.2 , 22A~F Attemperator 23, 23.1, 23.2, 23A~F Fluid distribution valve 24 Chilled water supply source 25 Water supply valve 26 Main valve 27 Water bypass valve

Claims (10)

A steam generator (01) having a hot gas passage (02),
- a superheater (11A) with a superheater outlet (12) for delivering a stream of hot steam (18);
- at least four heat exchangers (11B-11F);
- Economizer (11G) and
- distribution piping (21);
including;
The superheater (11A), the heat exchanger (11B-11F) and the economizer (11G) are connected in series, each having a fluid inlet (13) and at least one fluid distribution pipe (14). ), a plurality of heat exchange tubes (15) arranged in the hot gas passage (02), at least one collecting pipe (16), and a fluid outlet (17), the inlet of the economizer (12G) is connected to a cryogenic fluid supply source (24);
an outlet part (17A) of the superheater, a connection part between the superheater (11A) and the first heat exchanger (11B), and one of the at least four heat exchangers (11B-11F). at least one attenuator (22) is disposed at each connection between one heat exchanger (11B-11E) and the next heat exchanger (11C-11F);
The distribution pipe (21) is connected to the source (24) of the cryogenic fluid and the outlet (17G) of the economizer and is connected to the attemperator (22) via a separate valve (23). connected to each
A steam generator (01) characterized by: a main valve (26) is located at the fluid inlet (13F) of the last heat exchanger (11F) in the series (11B-11F); and/or
a fluid supply valve (25) is arranged at the inlet section (12G) of the economizer, and/or
a fluid bypass valve (27) is arranged between the source of cryogenic fluid (24) and the distribution pipe (21);
A steam generator (01) according to claim 1. at least two collecting pipes (16.1, 16.2) in which at least one of the series of superheaters (11A) and heat exchangers (11B-11F) has an attemperator (22.1, 22.2); ), in particular each of said attemperators (22.1, 22.2) is connected to said distribution pipe (09) via a separate fluid distribution valve (23.1, 23.2). There is,
A steam generator (01) according to claim 1 or 2. A steam generation system comprising the steam generator (01) according to any one of claims 1 to 3,
a control system capable of controlling a plurality of fluid valves (23, 25-27);
a temperature measurement system capable of measuring the temperature of at least one of said fluid outlet (17) and/or said fluid inlet and/or before at least one of said attemperator (22); a steam measuring system capable of measuring the steam fraction of and/or after;
A steam generation system, further comprising: The temperature measurement system is capable of measuring the temperature of each of the fluid outlet (17) and/or the fluid inlet, and/or
5. The steam generation system of claim 4, wherein the steam measurement system is capable of measuring steam fraction at each of the attemperators (22). The control system is capable of controlling the plurality of fluid valves (23, 25-27) individually or in groups stepwise, in particular depending on the temperature of the fluid outlet (17); and /or it is possible to control according to the steam ratio in the superheat reducer (22);
The steam generation system according to claim 4 or 5. A method of controlling a steam generation system according to any one of claims 4 to 6, comprising:
a) measuring at least the temperature and/or the temperature change at the fluid outlet (17);
b) comparing said temperature/temperature change with a predetermined value;
c) controlling at least one of the plurality of fluid valves (23, 25-27) in response to the comparison;
including methods. A method of controlling a steam generation system according to any one of claims 4 to 7, comprising:
a) measuring at least the steam fraction in the attemperator (22);
b) comparing the steam rate with a predetermined value;
c) controlling at least one of the plurality of fluid valves (23, 25-27) in response to the comparison;
including methods. a1) the temperature and/or temperature changes at all fluid outlets (17) are measured, and/or
a1) the steam fraction in all attemperators (22) is measured;
The method according to claim 7 or 8. a first predetermined value and/or a second predetermined value and/or a third predetermined value and/or in particular a fourth predetermined value for the steam proportion; the defined value is at least 60%, especially at least 75%, and/or at most 90%, especially at most 85% of the mass flow rate;
The method according to claim 8 or 9.