DE1932721A1 - Steam power plant that can be heated with fossil fuels and the process for their operation - Google Patents

Description

Emmanuel Stephen Miliaras, Winchester, Mass./USA

Steam power plant that can be heated with fossil fuels and the process for their operation

In 18 ^ 5 it was Green to increase the boiler efficiency of steam power plants of the submerged gas feed water preheater or an economizer was introduced that would reduce the flue gases leaving the steam boiler at a low temperature removes.

The subsequent introduction of the flue gas air preheater, in particular the rotational regenerative type contributed to Downsizing of the economizer and the later designs of steam power plants are in terms of size the heat transfer surface of the furnace, the economizer surface and the flue gas air preheater surface is economically balanced, whereby the whole system is optimally designed for continuous operation.

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The permissible pressure drop is also a design factor of the flue gas in the economizer, the relatively small temperature difference between the heat transfer involved media leads to a relative heat absorption of the economiser surface.

The limit of the temperature of the one entering the economizer d feed water is due to the need for full De-aeration of the feed water determined. The economizer outlet temperature is often below the steam generation temperature at this pressure or is restricted by restrictions for the Pipe temperature is sometimes determined below in the direction of flow of the economist.

The lower limit temperature of those leaving the economizer Flue gases are mostly given by the necessity that the temperature of the exiting flue gases must be above the condensation point, the structural due to the temperature Limits and stresses in the boiler tubes are determined on the basis of the fatigue strength and can be temporary may also be exceeded in the case of intermittent operation.

When generating electricity, one encounters short-term electrical loads often by switching off the feed water preheater, by working with overpressure or by discharging Excess steam on the turbine below the first stage.

Of the three main components, one is fossil fuel working steam power plant, the turbine offers a considerable increase in power plant investment with only a small increase Overload capacity and also the capacitor is under Operate with overload, accepting a certain loss of efficiency. Only the steam generator is due to the usual design considerations beyond those made by the manufacturer The specified nominal load can only be overloaded to a limited extent.

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The invention relates to an apparatus and a method for increasing the performance of the steam generator by additional heat is supplied to the economizer. The invention is suitable for existing steam power plant constructions as well as for planned drafts, insofar as the devices for increasing performance are available in the draft or for later application are provided so that the heat transfer surfaces the steam power plant parts, the material, the temperature-related construction limits as well as the size of the pipe system and auxiliary equipment of the entire system can be selected in order to be able to better utilize the higher output power of the steam generator.

Method and device for achieving the higher output power of the steam generator are referred to below further explained on the drawing. It shows:

Fig. 1 is a schematic representation of _a D mpferzeugers according to the invention and

FIG. 2 and FIG. 3 show a representation corresponding to FIG. 1 to explain various means of adding heat to the economizer.

The steam generator comprises a furnace 6 and one Breath gas boiler 7 (both of which can be further subdivided), disguised with closely spaced water and / or steam-cooled pipes o, burner 9? Tube bundle 1öa for overheating of the steam, tube bundle 10b for post-superheating and iikonomi serpipes 12.

In Fig. 1, additional fuel is placed in a refractory lined, next to the flue gas boiler and connected to this train 13 burned and the hot combustion products surrender of the economist. The additional fuel wix-d fed through a burner 14, while the Vex trennuttgslxift from a fan 15 from the *

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Ambient air or via a connecting cable from the main wind system is delivered. If the device for increasing the output power of the steam generator is inoperative, the throttle valve 17 is closed.

The additional combustion can alternatively or in addition direct in the space above the economizer in the flue gas boiler take place, the fuel is supplied through the burner 16, specifically to such a degree as it allows the the F _e uerungsraum leaving remaining oxygen when in the high excess air Firing chamber is worked, or by introducing additional combustion air and / or oxygen with the additional fan.

In Fig. 2 the additional combustion takes place in the adjacent flue 1S, with fuel and combustion air being supplied by a burner 19 similar to that in Fig. 1, with the exception that a fan 20 partially recirculates the flue gases mixed with the additional combustion gases is effected in the flue, wherein the V _e is ntilator 20 connected via a tube drawing 21 with the flue gas boiler below the iökonomisers and the heat transfer is improved in the Ekonomiserrohre by the increased flow of the flue gas masses. The throttle valves 22 and 23 are used to control the recirculating flue gas flow and to separate the adjacent combustion flue from the flue gas boiler when the device for increasing the output power of the steam generator is not working.

In Fig. 3, the hot combustion passages, which are generated in the combustion chamber by burning additional fuel, pass through refractory lined flues 2k, which are connected to several openings in the combustion chamber, to openings in the flue gas boiler room above the economizer (bypassing the tube bundle for overheating and Nachüberhitzung) and are mixed with the cooler combustion gases, whereby the T _e mpera, structure and the mass

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flow of the smoke gases that flow past the Ekpnomiserrohren, and thus also the heat supply to the economizer is increased. The flue gas flow through the train 2k is made possible by the negative pressure present in the area above the economizer in relation to the combustion chamber. The mentioned flue gas flow is supported, if necessary, by the action of a jet pump, the medium with the higher pressure in the jet pump consisting of cooler combustion gases taken from the area below the economizer by the train 25, or from ambient air, the pressure increase being caused by the fan 26 takes place. The medium with the lower pressure in the jet pump is formed by the aforementioned excess combustion gases, which flow from the furnace through the train 25a. Throttles 27 »28 and 29 control the flow of flue gas through the corresponding trains. They remain closed and thereby separate the combustion chamber from the flue gas boiler when the device for increasing the steam generation is not in operation.

The mode of action of one making use of the invention Steam generator can be described as follows:

When the steam generator is rated or lower Power is working, the throttle valves of the trains are closed for the circulation of the additional combustion gases, an additional combustion does not take place and the device to move the additional combustion gases is out of order, the efficiency of the steam generator is down not impaired by the presence of the device for increased steam generation,

For the desired increase in steam generation, the throttle valves on the trains are used to move the additional Combustion gases released, the device for moving the additional combustion gases comes into operation and the additional combustion takes place to the extent that it is necessary for the j

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Increase in steam generation is needed. The amount of additional combustion air, the additional combustion and the recirculation of the gases are _{regulated (} by the position of the throttle flaps, whereby the device for controlling the output power supports the movement of the flue gases. The draft for the combustion chamber is adapted to the new flow \> -Adjusted the conditions of the quench gas flow and the feedwater flow adjusted according to the increased output of the steam generator.

The efficiency of the steam generator is somewhat reduced, as the combustion gases enter the combustion chamber at a higher temperature leaving.

An application of the invention is shown in FIG. 30 is a high pressure turbine section, 31 is a low pressure turbine section that receives the reheated steam, 32 is the generator coupled to the turbine, 3h is the condenser, 35 are closed feed water preheaters, 37 are valves for controlling the steam extraction flow to the preheaters, 36 is a Ventilation (degeneration) preheater and 38 is a measuring and control device for the demand and output of electrical power.

Part of the increased output power of the steam generator due to the increased heat input to the economizer is carried out by the valve 33 derived, goes to the high pressure turbine section 30 and here also to the reheater 10b and closes the reheated steam on the way to the low-pressure turbine section 31 with approximately the same pressure and temperature at,

The increase in the heat supply to the economizer should still be in connection with a brief shutdown of the steam supply for the high pressure feedwater preheater to thereby reduce the steam flow of the turbine and thus the to increase the electrical output of the turbo generator. The feed water entering the economizer then has a lower temperature, so that the steam generator an additional supply of heat is required, switching off the

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Limited steam supply for the feed water preheater Duration is. The invention provides an additional supply of heat to the economizer, made possible by switching off the Steam supply to several feed water preheaters increases electrical power output, so that «without switching off the Feed water ventilator, the steam flow through the turbine is increased. The feed water deaerator that is not switched off is essential as it removes the oxygen from the Feed water removed.

The embodiment of the invention shown in FIG. 1 can be based on be operated in the following manner. Upon receipt of a signal from the monitoring device 33 that an increased power requirement indicates, the device for supplying the additional turbine power is triggered. from the monitoring device 3-3 outgoing Signals close the valves 37 for the feedwater preheater 35 », whereby the steam flow through the turbine increased, open the throttle valve 17 »operate the fan 15 and ignite the additional fuel of the burner 1 ^ (and / or 1 (i) and thereby increase the heat input to the economizer. The economizer receives after switching off the steam supply to the preheaters 35 feed water at a lower temperature. Venn the monitoring device 3 "5 or other devices or the computer detects the increase in power of the steam generator have, the valve 33 is opened and the low-pressure turbine 31 is supplied with additional steam.

The invention thus enables the peak demand to be met of electrical energy increasing the steam generation of a power plant by accepting a certain amount. Loss of efficiency, but with little additional effort, the well-known overload capacity of turbine and condenser is exploited and the Heat supply to the economizer is increased.

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Claims (1)

Claims Steam power plant covered with fossil fuels with a steam generation section (8), a superheater section (iOa, b) and an economizer section (12), the three sections being in a flue gas duct (6,7), and also the feed water from the economizer section to the steam generation section and the steam from the steam generation section to the superheating section and lines leading from this to the outlet, characterized by an additional device (13 and ^ k _t 16, 18 and 19, 2k) between the superheater section (10a, b) and economizer section (12) in the Flue gas duct (7) is arranged and can be switched on at peak load, for example by means of throttle valves (17, and 23 »28 and 29) and burner controls and the heat supplied to the water in the economizer (12) and thus also at this point by supplying additional hot and gaseous combustion products the steam energy output increases. 2. Plant according to claim 1 , characterized in that the additional device has an additional burner (i6) for burning fossil fuel, which brings the fuel into the flue gas duct between superheater and economizer, and that this flue gas duct has a combustion area for the fuel of the auxiliary burner contains * 3. Plant according to claim 1 or 2, characterized in that the additional device at least one first additional flue gas duct (i3, 18, 2k) which is connected so that it brings additional hot, gaseous combustion products to flow through the economizer in the flue gas channel, having. k. Plant according to claim 3, characterized in that an additional combustion chamber before said connection ■ '' - 8 909882/0444 application point. the additional flue gas duct (i3f 18) is connected, and that an additional burner (lh, 19) for fossil fuels brings this into the additional chamber. 5 · Plant according to claim k, characterized by a first flue gas fan (20, 26), which brings the flue gas into the additional combustion chamber and by an additional flue gas duct (21, 25) »which guides the gas to the fan and the flue gas from the flue gas duct in the Closeness to the economizer. 6 · Plant according to one of claims 3 to 5 »characterized in that that the additional device is arranged directly next to the economizer section and a flue gas return duct having, which is defined by the first additional flue and a second additional flue (21, 25) is and opens into the first flue that the second flue gas to the flue gas duct below the Economizer removes and that means for selective actuation of the additional device including the throttle valves (22, 23, 28, 29) are provided that make the connection the first and second flue gas ducts with the flue gas passages interrupt the steam generator. 7. Plant according to claim 3, characterized in that the additional device has a reflux gas channel with a second train (25) j which is connected to the flue gas passage below the economizer and a chamber (18) which the flue gas withdrawn by the second train with hotter Flue gas from a third additional pass (25a) mixes and that the chamber from? StrönfcUßg through the economizer in the first train müadei " Plant according to claim 7, characterized in that the Fan (26) picks up the flow from the wide train 909882/0444 AO A breath of gas is generated from it, that the third. Train (25a) to the furnace (6) of the steam generator is connected to the superheater section (10a, 10b) that the third train (25a) introduces smoke gases by suction as a result of the jet and the first train (24) the combined one Flow from the. second and third train receives and initiates to flow through the economizer (12) and that the Means for-selective. Holding the additional system throttle? have flaps (27j 28, 29), the connections of the close the first, second and third passages with the combustion chamber and the flue gas passages of the steam generator. 9 · Method for operating the system according to one of the preceding claims, characterized in that in the flue gas duct between "superheater and economizer additional hot, gaseous combustion products generated and to increase the amount of heat absorbed by the economizer can be added to the combustion products coming from the superheater. 10. The method of claim 9 for use with a steam generator with a feed water preheater (35) upstream of the economizer and a steam line that connects to the turbine directs the withdrawn feed water heating steam into the preheater, characterized in that the steam flow to the preheater j is further reduced so that the additional ones are called ■
and gaseous combustion products in the breath gas duct can flow. i11. Method according to claim 9 for use with a steam generator, which is combined with an electric turbo generator (32) with a high pressure turbine (30) and a ^ Low pressure turbine (31) and the one superheater section (iOa) and a post-superheater section (iOb), wherein the output line of the superheater section to the Input of the high pressure turbine, the output line of the high pressure turbine to the input line of the post-superheater unit and the output line of the night superheater - OK - 909882/0444 '* section connected to the inlet of the low-pressure turbine is, characterized in that part of the Flow from the outlet line of the post-superheater section (lOa) via a throttle valve into the entrance of the Low pressure turbine (31) is directed so that the additional hot and gaseous combustion products can flow through the flue gas duct, 12. The method according to claim 9 and 11, characterized in that that also the steam flow to the feedwater preheater 35 is reduced. - 1 1 - 909882 / 0U4