DE1170423B - Method and arrangement for regulating the steam temperatures in a once-through steam generator with two intermediate superheaters arranged in the flue gas duct - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: F 22 g

German class: 13 d- 11/06

Number: 1170 423

File number: S 585351 a / 13 d

Filing date: June 7, 1958

Opening day: May 21, 1964

The invention relates to a method and an arrangement for regulating the steam temperatures in a once-through steam generator with two reheaters arranged in the flue gas pass, from at least one of which is connected to the high-pressure working medium, with a bypass line having provided heat exchanger, wherein the distribution of the high-pressure working medium on heat exchangers and bypass line adjusted by a distribution valve and also the focus of the Heat transfer is laid in the steam generator.

It is known to have double reheating To divide a steam generator into two parallel parts, each of which is a reheater having. By changing the load on the two parts of the steam generator, the flue gas applied differently to the two reheaters. This known arrangement has the Disadvantage that the steam generator is made more expensive by this structure and that to a control margin the two parts of the steam generator can never be fully utilized at the same time.

It is also known in the case of a steam generator with an intermediate superheater to provide the superheater with a heat exchanger connected to the high-pressure working medium, which has a bypass line, for the purpose of temperature control. The distribution of the high-pressure working medium to the heat exchanger and bypass line is set by a distribution valve. In connection with this, it has also become known for two reheaters. to provide a known swivel burner to regulate the temperature of the second reheater. Although this arrangement is significantly simpler than the two-part construction of a steam generator, it has the disadvantage that the position of the swivel burner not only influences the temperature of the steam in one of the reheaters, the temperature of which is to be changed thereby, but also the temperatures of both another superheater. It can happen that the requirements of the two reheaters are opposite. Therefore z. B. an increase in the temperature of the second reheater by the swivel burner an increased water injection into the high pressure steam serving for heat transfer to the reheated steam necessary to lower the m undesirably increased temperature of the reheater provided with the heat exchanger again. Apart from the fact that ζ. B. such injections in principle un-method and arrangement for regulating the
Steam temperatures in a once-through steam generator with two in the flue
arranged reheaters

Applicant:

Sulzer Brothers Aktiengesellschaft,

Winterthur (Switzerland)

Representative:

Dipl.-Ing. H. Marsch, patent attorney,

Schwelm (Westphalia), Westfalendamm 10

Claimed priority:

Switzerland of March 12, 1958 (56 930)

are desired, complications arise which make it difficult to regulate the steam generator will.

^a 5 According to the invention, this disadvantage of the latter arrangement is eliminated in that the relocation of the center of gravity of the heat transfer depending on the sum of the deviations of the output temperatures of both reheaters from the setpoint, the adjustment of the distribution valve, however, takes place depending on the difference between these deviations.

As a result, the swivel burner is not adjusted depending on the requirements of a single reheater, but with consideration for both reheaters. That ensures better regulation and also a minimal amount or none at all Water for injection into the high-pressure steam, which takes into account the salinisation of the superheater and also has a favorable effect on the thermal efficiency of the system.

The arrangement for performing the method according to the invention is characterized in that the heat exchanger consists in a manner known per se of two pipe strings arranged one inside the other and is also arranged in the flue.

Several exemplary embodiments of the invention are shown schematically in the drawing. It shows

1 shows the scheme of a steam generator system with a multi-stage turbo generator,

409 590/161

3 4

F i g. 2 an arrangement of the superheaters in the steam. If a fan is used for the air supply, see

generator, the servomotor 47 is used instead of the air flaps

Fig. 3 shows an arrangement of the reheater, for example, the speed of the fan motor so

with mutual heat exchange and ensure that the same correction is achieved.

4 shows an arrangement of the superheaters with 5 increasing the amount of fuel

Control of the flue gases. the thermal energy developed in the furnace. the

In Fig. 1, feed water is from the start-up temperature at the outlet of the control line 10 of the

vessel 1 with the help of the feed water pump 2 rises above the evaporator 9, the sensor 49 of this strand

Feed water line 3 promoted in the economizer 4. acts on the correction organ 50, which is the valve

At the outlet of the same, the feed 51 branches out to regulate the feed water quantity in the line.

water line into the cooling line 5, which gives the command through the device 3 via the impulse line 52:

second reheater 6 is passed through, more water.

and into the bypass line 7. Both lines carry Da the amount of heat supplied despite the increase

to the distribution valve 8, which with the evaporator 9 reduces the amount of water and steam generated by the latter.

is bound. 15 exceeds the taken energy, the tem-

The feed water flows through the evaporator 9, temperature of the flue gases. The further from the firebox

in which it largely passes into vapor form. removed, the higher the relative increase, so

In the water separator 11, the water phase is separated from that of the intermediate superheaters 6, 15 opposite

separated, while the steam through the primary to the live steam superheater 17, but also at

Live steam superheater 12 to live steam distribution 20 second superheater 6 opposite the first 15 itself

valve 13 arrives. The relatively greater increase is set at the distribution valve 13.

Heating line 14, which through the first intermediate over- Die due to the higher flue gas temperature

heater 15 is passed, and the bypass line caused the output temperature to increase

16 connected. These two lines open out to the live steam superheater 17 of the control device

in the secondary live steam superheater 17, reported by 25 53 by the temperature sensor 54. As a result-

that from the live steam via the high-pressure line which causes the device 53 via the im-

18 reaches the high pressure turbine stage 19. pulse line 55 and the actuator 56 an adjustment

The high-pressure stage 19 has an intermediate pressure extraction of the swivel burner 57 and thus the fire position in the

Via the shut-off valve 21. The combustion chamber 58, which is open to medium pressure, goes down.

Tense steam flows through the line 22 to the 30 so that the center or the shifts

first reheater 15 and at the outlet of the center of heat transfer to the whole,

same via the line 24 with the temperature this transfer serving heating surface, which in the

sensor 25 and the quantity measuring device 26 to the entry fire or radiation room 58 and into the smoke

the medium-pressure turbine stage 27. By means of the shut-off gas ducts 59, 61 is present. So z. B. valve 28 can medium pressure steam from the line 35 after lowering the burner 57 the lower parts

22 a consumer, not shown, supplied to the entire heating surface of the evaporator 9 more strongly,

will. The medium-pressure turbine stage 27 also has the upper parts weaker than in the higher position of the

Intermediate steam extraction, which is heated by means of the exhaust burner 57, so that the center or the

Check valve 29 is regulated. Focus of heat transfer through the ge-der 40 called the heating surface emerging from the medium pressure stage 27 oppose the entry of the

Low pressure steam reaches the steamer 9 via line 31. This also applies to the

second reheater 6, the outlet of which the complete heating surface of evaporator 9, live steam super-

Line 33 with the temperature sensor 34 and the heater 12, 17, reheater 15, 6 and Ekono-

Quantity measuring device 35 with the low-pressure turbine miser 4, so that the superheaters 12, 17 are somewhat less level 36 connects. The 36 45 are heated in the LP turbine stage and the output temperature of the

Relaxed steam will be kept at the setpoint via line 37 to superheater 17

Capacitor 38 led. The three-stage turbine can.

drives the power generator 39. To regulate the load, the output temperatures of the preheater 15 and 6 are still too high at constant speed. ₅ o On the common message of the sensors 25, 34 The condensate is from the condenser 38, the controller sends a pulse via the pulse by means of the two condensate pumps 42 and through line 62 to the controller 63, whereby this the fresh the downstream preheater 43 in the steam flow to Heating line 14 reduced and promoted to start-up vessel 1. Bypass line 16 enlarged. The heating in the first The mode of operation of the control should be shown on hand 55 reheater 15 so much that despite the following example. higher flue gas temperature its output temperature occurs, in that the temperature and thus the temperature of the MD steam in generator 39 by switching on additional consumers of line 24 reaches the setpoint and the MeI is heavily loaded, the speed of the manure drops of the sensor 25 to the controller 53 stops. Turbo generator. The speed controller 41 reports 60 as a result of the MD-, which has fallen to the setpoint value, via the message line 44 to the controller 45 for the steam temperature in the line 24, the LP fuel is also the change in speed. The controller 45 evaporates the vapor temperature in the line 31 normally. This now causes further flue gas heating via the impulse line 46 of the second intermediate over-opening of the fuel control valve by the servo heater 6, however, is relatively higher, so that its exhaust motor 47. Through this impulse, the input temperature is retroactively 65 still above the setpoint. Therefore, or secondarily by means of the servo motor 48 for the, the sensor 34 still reports the amount of combustion air to the controller 53 after the temperature increase. Corrected as a result of the remaining requirement of the increased amount of fuel. The controller 53 sends the difference via the pulse

line 64 the actuator 65 a pulse. This adjusts the distribution valve 8 so that more feed water flows through the cooling line 5 and less through the bypass line 7 and thus the temperature in the line 33 drops to the setpoint.

As a result of the greater amount of water and steam, the increase in load and the target speed have been met reached again at the turbo generator as well as the normal position of the speed controller 41.

As a second example, the controller 53 could respond to the message from sensor 54 instead of lowering the Burner 57 a correction of the fire intensity, d. H. effect of fuel and air volume. The correction the amount of fuel goes through the pulse line 66, by the pulse of the controller 45 to the Actuator 47 corrected a little, d. H. is reduced and from this, as described, the amount of air is adjusted will. But it could also from the controller 53 via the pulse line 67 with the help of the servo motor 48, the amount of air is reduced and now vice versa via the pulse line 68 from the servomotor 48 of the Servomotor 47 can be corrected to reduce fuel consumption. This could result from a fire shift apart from the heating and cooling in the superheaters 15 and 6 as described be made.

A third example would be that the correction of the fire intensity, as in the second example, by the Controller 53 takes place, but on the common message from sensors 25 and 34 of controller 53 a Fire relocation and a change in response to a remaining difference message from sensors 25 and 34 caused by heating by means of line 14 or cooling by means of line 5.

The reheater steam of the medium pressure stage and that of the low pressure stage can both can be heated with live steam as well as with intermediate superheater steam of the medium pressure stage. as well can also cool the reheater steam both with feed water and with Reheater steam take place from the low-pressure stage.

In order to accelerate the control process, the controller 71 could respond to a message from the sensor 54 and from the controller 72 on a message from the sensor 73, the injection of water from the lines 74, 75 in the superheaters 17, 12 at too high a temperature increase.

When steam is withdrawn via the valves 21 or 28, the amount of steam already changes in the first Reheater 15. The quantity measuring device 26 reports this to the controller 53, which sends a pulse Reduction of the heating of the line 14 sends until the temperature at the sensor 25 has fallen to the setpoint is. But less steam also flows through the second reheater 6. To the message of the quantity measuring device 35, the controller 53 will reduce the cooling by means of the line 5 until the temperature at the sensor 34 has risen to the setpoint. When steam is withdrawn through the valve 29 only a regulation of the cooling in the reheater 6 is to be effected.

The reheaters 6 and 15 partly consist of two pipe strings plugged into one another. Of the The inner branch of the reheater 15 is used for heating and is therefore the heating surface on the flue gas side of the reheater 15 is undersized in relation to the normal amount of steam flowing through.

In contrast, the flue gas-side heating surface of the reheater 6 is oversized because of the inner pipe string is used for cooling.

If the regulation is carried out by additional heating of one reheater, then the heating cable is advantageously arranged at the beginning of the reheater in question, where the Temperature difference is large. In the case of regulation by cooling, however, the cooling line is in the ίο provided near the superheater end, depending on the expected temperatures of the three Media, flue gas, intermediate steam and cooling agent and according to the geometric relationships (pipe diameter), is passed to the other end of the reheater or not, so that the pipe material is thermally optimally loaded.

The internal cooling apparently has the disadvantage compared to the heating, a larger reheater heating surface to require. In fact, however, on the high-pressure side, in the case of the evaporator 9 or at the live steam superheaters 12, 17 a corresponding heating surface can be saved. Depending on the temperature differences, a Heating or cooling manage with shorter inner pipes.

In Fig. 2 the first reheater is divided into two parts 76 and 77 which are connected to one another are. The part 77 is to the line 22 and the part 76 to the line 24 from FIG. 1 connected.

The second reheater 78 with connection to the lines 31 and 33 is between them two parts arranged in the flue gas duct 61. The arrow 79 represents the direction of the flue gas flow This joining the two reheaters has the advantage that in one Displacement of the fire or the center of heat transfer a difference in the relative Change in the flue gas temperature of one reheater compared to the others in the essentially lapses, which simplifies the regulation.

There are a total of fifteen different possible combinations for the application of Heating and cooling with two reheaters, whether individually or together, in one or at the same time in both reheaters. In special cases, one or the other can do a special Have advantage. If both reheaters are set up for cooling or heating, then under Under certain circumstances, the use of a fire relocation or smoke gas circulation can be dispensed with. If one of the reheaters is now set up for internal heating or cooling, z. B. the Regulation of the outlet temperature from this reheater with the aid of the coolant or heating medium inlet temperature or regulated flow rate and the outlet temperature of the other reheater with the help of one or more of the known types, such as burner pivoting, flue gas circulation, flue gas bypass, disconnection or connection and control of rows of burners or water injection, being held.

In the case of less favorable load conditions or higher demands on the regulation, additional to regulate the fire position and the heating of a reheater, the former due to the Sum of the deviations in the output temperatures of the two reheaters, the latter, however, due to

the difference, the control system can be supplemented so that with an increase in heating power in the sense a disturbance variable feed, a pulse is given to the controller of the swivel burner, which this swings away from the reheater part. In addition, this adjustment of the swivel burner can the Fuel or feed water regulator are switched on, so that the pivoting is a reduction the fuel or an increase in the feed water supply.

In the examples described above, the heating with live steam and the cooling with Feed water made. Instead, FIG. 3 Heating and cooling by exchanging steam

second part 114 lies in channel 105. In room 108 the economizer 115 is housed, its exit on the one hand to the heating section 116 in the end of the reheater 112, on the other hand via the bypass 117 is directly connected to the distribution valve 118, into which the outlet line 119 from Strand 116 opens.

The closing flap 121 for the bypass channel 107 and the closing flaps 122 for the channel 106 ίο are operated jointly, but in the opposite sense, by the servomotor 123. When the flap 121 is opened, the flaps 122 close. Thus, more flue gas passes through the bypass 107 and less through the channel 106. The part 113 of the second

from a reheater with steam from the 15 main steam superheater gets more heat; the another reheater. second part 114 in channel 105 and the intermediate

In the channel 61, however, flue gas flows less in the direction of the superheaters 111 and 112. if Arrow 81 first through the first reheater so that the output temperatures of the live steam 82. The MD superheater 114 and the reheater 111 pass through line 22 (FIG. 1) into the heat exchanger 83, which can be held from the outside, the valve 118 regulates this is not heated, and is heated in it by the low pressure level of the cooling through the line 116 to the corri steam, which near the end of the second yaw of the temperature of the LP steam at the outlet Reheater 84 is removed. In the first of the second reheater 112. Part of the intermediate superheater 82 is the MD steam. If intermediate steam extraction is provided, it can

only in exchange with the flue gases, while the a _{5 shows} the amount of steam withdrawn instead of the amount of steam flowing through the second part with an inner pipe string 85, through the LP steam from line 31, interference pulse to the controller for the heating or Cooling flows and cooling of the MD steam can be switched on.

causes. De _1n present state of the art in accordance with the

The controller 45, 50, 53, 71, 72 as a P, I, PI, PD or reheater 84 is interrupted between the supply and return lines 86, 87. The PID controller feed line or a combination thereof. 86 leads to the distribution valve 88, to which the line 89 is _Z- ß. Heating one and cooling the other

to the exchanger 83 and the bypass line 91 to the _{Γεη reheater is} provided, so the return line 87 can be connected. The line 31 control device 53 (Fig. 1) so designed, leads to the distribution valve 92, which through the supply line ₃₅ that first the one means (z. B. the heater) full

93 is connected to line 85. The return line is used before the cooling starts. It

94 closes the branch 85 and a bypass line, but both means can also come to the valve 92 at the inlet of the reheater application at the same time. Are more than two actuators 84 on. fo _r the heating and cooling pipes present can

The circuit according to FIG. 3 also has the advantage of successively heating and cooling as essential, that excess temperatures of the one in between are reversed. But they can also be combined, Superheater and sub-temperatures of the other by z. B. the heating of a reheater reheater compared to the respective target heaters and at the same time utilize those of the other is reduced faster and with smaller exchange areas, until the final control element because the heating of the MD-45 has reached position and only then the cooling Steam in exchanger 83 is at the same time a cooling is reduced or increased.

The pipe system of the reheater will be arranged in the boiler, as far as foreseeable, in such a way that that in the event of a fire being relocated, those released to the two reheater pipe systems Amounts of heat remain the same among themselves or - depending on the desired characteristics - in the change desired senses. Should the heat distribution not increase significantly in the event of a fire relocating

the grate firing 101 (Fig. 4), so a 55 can be changed, so the pipe systems of one Shifting the center of the heat transfer reheater penetrate those of the other by means of a controlled flue gas bypass, surrounded or otherwise nested in one another are sufficient. Be in the furnace 102 (Fig. 4) above the grate, and of course you can 101 is the evaporator 103, to which the partial parts of the one, the other or both in between The first fresh superheater, which is still in the radiation part, is in the area of the high-pressure steam tube steam superheater 104 connects. be nested in the system or through-

The flue gas channel 105 divides into the channel 106 penetrate, or parts of this system can open into the and the bypass 107, both nested in the end space 108 pipe system of the reheater, from which the channel 109 to the chimney or penetrate this. From the different. In the duct 106, the first intermediate superheater can be arranged, especially heater 111 and the second intermediate superheater 112
housed; The first part 113 is in the bypass 107
of the second live steam superheater, during the

development of the LP steam at the end of the reheater. The cooling of the MD steam is also on Pipe string 85 a heating of the LP steam before the entry of the reheater 84.

The servomotors 96, 97 receive their impulses Via the pulse lines 98, 99 from a controller, not shown, such as. B. the controller 53 in Fi g. 1.

If a fire relocation is not possible, as with

the following into consideration:
1. The second reheater is located in the flue gas flow between the part of the first

Reheater with the inner pipe string and the end of the first reheater.

2. The second reheater is located in the flue gas flow upstream of the end section of the first Reheater.

3. A combination of 1st and 2nd

If both reheaters are set up for internal heating or cooling, the heating or cooling systems can be used. Cooling lines connected in parallel or in series ίο be switched; Depending on the temperature conditions, they can be placed after or between the feed water preheaters or be connected to the economists or also bypass these apparatuses. By Such a bridging can, if necessary, reduce the inlet temperatures of the evaporator will.

Heating lines are preferably connected in the high-pressure section before an end superheater. in the If two heating lines are connected in series, between the two heating lines overheating may be appropriate.

Claims (5)

Patent claims: 1. Procedure for regulating the steam temperature => 5 fittings in a once-through steam generator with two reheaters arranged in the flue gas duct, at least one of which has a heat exchanger connected to the high-pressure working medium and provided with a bypass line having, wherein the distribution of the high-pressure working medium on the heat exchanger and bypass line is adjusted by a distribution valve and also shifting the focus of heat transfer in the steam generator is characterized in that the relocation of the focus of the heat transfer depending on the sum of the deviations of the output temperatures of both reheaters (6, 15) from the setpoint, the Adjustment of the distributing valve (8, 13), however, as a function of the difference between these deviations he follows. 2. The method according to claim 1 in the case of two heat exchangers equipped with distribution valves, characterized in that the adjustment of the two distribution valves (8, 13) by the relevant Controller works in opposite directions. 3. Arrangement for carrying out the method according to claim 1, characterized in that the heat exchanger consists in a manner known per se of two pipe strings (5, 6; 14, 15; 112, 116) arranged one inside the other and also in the flue gas duct (61; 106) is arranged. 4. Arrangement according to claim 3, characterized in that the heat exchanger in on is known to flow through the superheated steam. 5. Arrangement according to claim 3, characterized in that that the heat exchanger is arranged in a manner known per se in the flow of the working medium upstream of the evaporator (9) is. Considered publications: German interpretation document S 37776 Ia / 13d
(announced on July 19, 1956); Swiss patents No. 280 010,
968, 322433; French Patent No. 1110091; British Patent No. 793,048; U.S. Patent No. 2,685,279. 1 sheet of drawings 409 590/161 5.64 © Bundesdruckerei Berlin