CN102859277A

CN102859277A - Process and apparatus for heating feedwater in a heat recovery steam generator

Info

Publication number: CN102859277A
Application number: CN2011800079681A
Authority: CN
Inventors: Y.M.雷克特曼
Original assignee: Nooter Eriksen Inc
Current assignee: Nooter Eriksen Inc
Priority date: 2010-02-01
Filing date: 2011-01-31
Publication date: 2013-01-02
Also published as: WO2011094663A3; US20120312019A1; WO2011094663A2; RU2012137222A

Abstract

A feedwater heater (14) in a heat recovery steam generator (A,B) lies within a flow of hot exhaust gas. The feedwater heater (14) converts subcooled feedwater into saturated feedwater water, the temperature of which is only lightly above the acid dew point temperature of the exhaust gas so that corrosive acids do not condense on coils (18) of the feedwater heater (14). Yet the temperature of the saturated feedwater lies significantly below the temperature of the exhaust gas at the coils (18), so that the coils (18) operate efficiently and require minimal surface area. Pumps (26, 28, 30) elevate the pressure of the saturated feedwater and direct it into an economizer (64, 90) where, owing to the increase in pressure, the water is again subcooled.; The economizer (64, 90) elevates the temperature still further and delivers the higher pressure feedwater to evaporators (34, 70, 78) that convert it into saturated steam that flows on to the superheaters (50, 78, 84). Higher pressure pegging stem admitted to the feedwater heater (14) controls the pressure - and temperature - of saturated steam and water in the feedwater heater (14).

Description

The processing procedure of heated feed water and equipment in the heat recovery steam generator

Related application

The present invention obtain or otherwise require to be filed in the priority of the 61/300th, No. 222 U.S. Provisional Application on February 1st, 2010, at this in conjunction with this application as a reference.

Technical field

The application relates to boiler (boiler), and more specifically relates to the heat recovery steam generator that has improved the feedwater heating.

Background technology

In in recent years, the boiler that is designed to by absorbing energy aqueous water to be changed into steam from hot gas has become more efficient, and this high efficiency all stems under lower temperature draw heat in the gas of (these gases otherwise may be discharged into residing temperature the atmosphere) mostly.But the raising of this efficient has produced the problem of itself, if undecided may causing of these problems caused corrosion to the low-temperature surface of boiler.

Heat recovery steam generator (HRSG) has represented an important class efficient boiler.Typical HRSG works in a kind of system that comprises the gas turbine that is driving generator.This turbine gives off the waste gas that temperature raises, and these gases flow into HRSG, and HRSG is draw heat therefrom, and so that excessively cold aqueous water is changed into superheated steam, this finishes under several atmospheric pressure usually.These steam provide power for steam turbine, and this steam turbine drives another generator then.HRSG has a plurality of around the pipe group, and these last on the direction of pipe group in gas flow form the part of feed-water heater usually.It receives the condensed water that obtains from the low-pressure steam that steam turbine gives off, and makes the temperature rise of these water before these water are discharged into one or more evaporimeters, and this evaporimeter changes into saturated vapor with water.Superheater changes into superheated steam with these saturated vapors then, to provide power to steam turbine.

The burning of fossil fuel (such as natural gas, fuel oil or coal) produces hot waste gas, and it provides power to gas turbine, and flows through HRSG.By the time hot gas arrives when the feed-water heater of HRSG rearward end, and its temperature is quite low, but temperature should not yet be hanged down to the degree that can make at the area of heating surface of feed-water heater acid condensation.After all, what burning produced mainly is the water of carbon dioxide and gas phase, but these gases also will comprise the Determination of Trace Sulfur of sulfur dioxide and sulfur trioxide form.Those compositions will be combined with water the sulfuric acid that generation has high corrosion.As long as the temperature of the area of heating surface remains on more than the acid dew-point temperature (acid dew point temperature) of waste gas, then SO ₂And SO ₃To can not produce adverse effect by HSRG.If but any surface drops to the following temperature of acid dew-point temperature, then sulfuric acid will be on this surface condensation and corrode this surface, and will have the surface of rapid wear on the feed-water heater.

Depend on the fuel that consumes, dew-point temperature is different.For natural gas, the temperature of the area of heating surface should not drop to approximately below 140 ℉.For most of fuel oils, it should not drop to approximately below 235 ℉.

Be pumped to condensate that HRSG will be converted to saturated vapor and usually will arrive feed-water heater with the temperature of 100 ℉ roughly.But if be guided through feed-water heater with this temperature, then sulfuric acid will condensation on the downstream surface of this feed-water heater.For all surface (being generally around pipe (coil) surface) with feed-water heater maintains more than the acid dew-point temperature, in some HRSG, the feedwater of a part of low temperature is directly transferred to the first evaporimeter (Fig. 1) at branch road.This has reduced the load on the feed-water heater.Usually, by feed-water heater around pipe rather than flow to a part in the water that has heated of the first evaporimeter, be recycled and mix with the condensate of cooler, so that just entering temperature around the water of pipe above acid dew-point temperature.Water in the branch road is when being used, and the beneficial effect of the rising of the initial temperature in the unrealized feed-water heater, and has reduced the efficient of HRSG.This recirculation needs recirculation pump and valve, and the higher temperature of temperature that the feedwater that is discharged out is reached may need than other side, and this has excessively reduced efficient.And the temperature when waste gas enters into feed-water heater is often high a lot of unlike the temperature of the water that leaves feed-water heater, and therefore, and feed-water heater must comprise larger more expensive around the pipe cohort.Large-scale feed-water heater this and that branch road couples has caused significantly pressure drop between its two ends, and this has applied sizable load to feed pump.

The conventional process (namely make feed-water heater use recirculation, and also may have branch road) that solves acid condensation can work, and in this case, the drawn waste gas of combustion of natural gas has relatively low acid dew-point temperature, and they are about 140 ℉.For lower acid dew-point temperature, the waste gas of feed-water heater when flowing through feed-water heater with between the feedwater of heater in pipe, can have the relative large temperature difference, therefore do not need to have very large surface area around pipe.But when dew-point temperature when higher (such as being 230 ℉ for the waste gas that obtains from some fuel oils), the feed-water heater place can not have the large temperature difference (feed-water heater becomes very intensive-see Fig. 1).Therefore, feed-water heater needs a large amount of around tube bank, so that conventional feed-water heater itself is more expensive, and simultaneously need to be from sizable pressure reduction (head) of condenser pump, forcing water by it and to enter economizer (economizer), and the low pressure evaporator after it.

In addition, most of HRSG (low pressure (lp), middle pressure (ip) and high pressure (hp)) lower superheated steam that produces of arbitrarily downgrading at three.Feed-water heater directly is discharged into low pressure evaporator with a part through the feedwater of heating usually, forces feedwater by the required pressure reduction of feed-water heater so that condenser pump not only must overcome, but also must overcome the residing pressure of low pressure evaporator work.The pump of several ip and hp is gone in residue feedwater, and these pumps force it to pass economizer, so that its temperature further raises, so that it is more suitable for ip and hp evaporimeter in the more upstream end that is positioned at waste gas streams.

Description of drawings

Fig. 1 is the feed-water heater that uses in the HRSG of prior art and the schematic diagram of low pressure evaporator and economizer;

Figure 1A is the feedwater in feed-water heater and economizer and flow through the avatars of the temperature difference between the waste gas of this feed-water heater and economizer in the prior art;

Fig. 2 shows the schematic diagram with heat recovery steam generator of arranging through improved feed-water heater, economizer and pump that all makes up according to embodiments of the invention;

Fig. 2 A is in the feed-water heater of the described HRSG of Fig. 2 and the feedwater in the economizer and flows through the avatars of the temperature difference between the waste gas of this feed-water heater and economizer;

Fig. 3 is the schematic diagram of implementing alternative heat recovery steam generator of the present invention; And

Fig. 3 A is in the feed-water heater of the described HRSG of Fig. 3 and the feedwater in the economizer and flows through the avatars of the temperature difference between the waste gas of this feed-water heater and economizer.

The specific embodiment

With reference now to accompanying drawing,, heat recovery steam generator (HRSG) A(Fig. 2 of draw heat from thermal current) provides the superheated steam that is under some pressure ratings.These steam can be directed into steam turbine to provide power to it.After passing through turbine, these steam discharge with lower pressure and temperature, and are condensed into supercooled liquid water, and these supercooled liquid water circulations are got back to HRSG A, again to be converted to superheated steam.

HRSG A comprises (Fig. 2) shell 2, and it is a kind of pipeline with entrance 4 and outlet 6 basically.HRSGA also is included in a series of heat exchangers that comprise within the shell 2, and their function is to a great extent as their title is described.In addition, HRSG A comprises pump, valve, and these heat exchangers, pump and valve is connected together so that the pipeline that HRSG A works or conduit.The hot waste gas that is obtained by combustion of fossil fuel enters shell 2 at entrance 4 places, through the heat exchanger of several draw heats from these hot waste gas, and is discharged away at outlet 6 places.Usually, waste gas represents the emission of gas turbine, the gas-turbine machine burning be natural gas or fuel oil, or or even coal.It can enter shell 2 between 900 ℉ and 1200 ℉.Main carbon dioxide and the water of producing of burning.But fossil fuel generally includes the sulphur of trace, so burning also produces a small amount of sulfur dioxide and sulfur trioxide.Go out sulfuric acid for fear of the condensation on the surface of heat exchanger of this composition, those surfaces must be maintained more than the acid dew-point temperature of waste gas.Certainly, sulfuric acid has high corrosion, and will corrode most metal, comprises the metal of those manufacturing heat exchangers.Water flows through HRSGA with the direction opposite with the flow direction of hot waste gas usually, thus the most impaired be those heat exchangers that are positioned at rearward end, that is to say, be the heat exchanger that is positioned at the waste gas streams downstream.Have at waste gas in the situation of high acid dew point (gas that for example, obtains by oil inflame) especially true.The surface that such gas runs into should be maintained at more than 230 ℉ at least.

In fact, the most erodible is that the water (being called feedwater) that flows into is heated and so that the cold feedwater of mistake more effectively is converted to those heat exchangers of steam.Although these heat exchangers can be worked under relatively high temperature, they are the aqueous water among them and through keeping the very effective temperature difference between their hot waste gas still.This is to realize by being divided into two parts to the heating of feedwater, that is, and and evaporation section and can feel part.In evaporation section, the temperature of feedwater is kept invariable.In can feeling part, the steady temperature of the temperature of feedwater from evaporation section begins to raise.

From the rearward end of HRSG A, starting or condenser pump 10 pump into water-supply line 12 with aqueous water (normally from the cold condensate of the mistake of steam turbine), and water-supply line 12 leads to evaporation feed-water heater 14, and the evaporation section of described heating occurs at this place.Compare with comprising large-scale feed-water heater in traditional HRSG of pipe group and recirculation pump, feed-water heater 14 has drum (steam drum) 16 and small-sized around pipe group 18 below this drum 16.Drum 16 is connected to around pipe 18 bottom by down-comer 20, down-comer 20 so that aqueous water can flow to around pipe 18 lower ends from drum 16.Upper end around pipe is communicated with the lower area of drum 16 by tedge 22.Within pipe 18, a part of water is transformed into saturated vapor, and aqueous water and saturated vapor is discharged in the drum 16 by tedge 22 around pipe 18.By free convection make water in the lower circulation of invariable temperature (steam and water saturation temperature) through bag 16, down-comer 20, around pipe 18 and tedge 22, but also can provide pump to assist this free convection.

Drum 16 comprises saturated aqueous water, and the saturated vapor above aqueous water.Certainly have aqueous water under the minimum temperature of pipe 18, these aqueous waters are introduced to around pipe 18 by down-comer 20, and around the common a little higher than acid dew-point temperature of minimum temperature of managing 18.In the situation that fuel oil produces waste gas, dew-point temperature is generally 230 ℉, but may be higher.Condensate will enter drum 16 with relatively low temperature (generally roughly 100 ℉), and be condensed into saturated vapor in drum 16, and mix with saturated water.Certainly, temperature can raise really, and moment reaches and is discharged in the down-comer 20 and goes to therefrom minimum temperature around pipe 18 water.Hot waste gas makes around the aqueous water energy of pipe in 18 and improves by around pipe 18, and will be wherein some change into saturated vapor, this and circular form evaporimeter are closely similar.The pressure of steam and aqueous water is being controlled the temperature of saturated water and steam in drum 16.

Some aqueous waters in drum 16 cycle through feed-water heater 14 again.But the volume of the water in drum 16 remains unchanged substantially, although therefore some water circulate again, the water supply point that enters that more water is introduced by water-supply line 12 substitutes.Replaced water flows out bag 16 by discharge pipe line 24, and this discharge pipe line 24 leads to three feed pump-low pressure (lp) pump 26, middle pressure (ip) pump 28 and high pressure (hp) pump 30.In fact, two in these three

pumps

26,28,30 or even all can be combined into the single pump with a plurality of classifications or floss hole.All with almost identical temperature discharging aqueous water, this temperature is exactly the temperature of the saturation water in the drum 16 of feed-water heater 14 to these three

pumps

26,28,30 basically, and they were discharged with the pressure that increases gradually, so water became cold once more.

Lp pump 26 is transported to low pressure (lp) evaporimeter 34 by low pressure water supply line 32 with aqueous water, and it changes into saturated vapor according to the work of Natural Circulation principle with water.For reaching this purpose, lp evaporimeter 34 has drum 36, and water supply line 32 leads to this drum 36.In addition, the below that is positioned at bag 36 has around pipe 38, and down-comer 40 leads to around the bottom of pipe 38 from wrapping 36, and tedge 42 leads to drum 36 from the upper end around pipe 38.The higher saturated vapor of pressure and temperature when lp evaporimeter 34 produces pressure and temperature than feed-water heater 14 work.Saturated vapor A is by leaving lp evaporimeter 34 from the extended discharge pipe line 44 in drum 36 tops.

In the work of lp evaporimeter 34, supercooled liquid water enters drum 36 by lp water supply line 32.Herein, water mixes with saturated vapor-and this is the product of lp evaporimeter 34, because aqueous water enters down-comer 40 and flows to around pipe 38 bottoms.Pass around managing 38 o'clock in rising, some water change into saturated vapor, and these saturated vapors enter drum 36 together with the water that remains liquid phase.The two temperature all surpasses the temperature that enters the water of drum 36 at water supply line 32 places from lp pump 26, and this temperature is exactly the temperature by the water of feed-water heater 14 discharges basically.Saturated vapor leaves drum 36 by discharge pipe line 44, and aqueous water is owing to the free convection by down-comer 40 circulates again simultaneously.

Discharge pipe line 44 is directed to low pressure (lp) superheater 50 with saturated vapor, the upstream that low pressure (lp) superheater 50 is positioned at from the waste gas streams of feed-water heater 14 and evaporimeter 34.It changes into superheated steam with these saturated vapors.Superheated steam leaves lp superheater 50 by lp steam pipe line 52, and lp steam pipe line 52 can lead to the low-pressure stage of steam turbine.Present pressure is controlled during 34 work of 52 pairs of lp evaporimeters of steam pipe line.

The discharge pipe line 44 that leaves from the drum 36 of lp evaporimeter 34 also is connected with the drum 16 of feed-water heater 14 with the valve 56 of reviewing on this pipeline 54 that is connected by reviewing pipeline (pegging line) 54.Owing to occuping the lp pump 26 between feed-water heater 14 and the lp evaporimeter 34, the pressure in the latter's the drum 36 surpasses the pressure in the former drum 16.Review the higher steam of valve 56 allowable pressures enters feed-water heater 14 from lp evaporimeter 34 drum 16, so that feed-water heater 14 is worked under the pressure of expectation.And, when waste gas streams pervaporation device around pipe 18 time (in fact, when waste gas streams excessively last around pipe 18 or around the downstream of pipe 18 time), this pressure is associated with saturation temperature above the waste gas dew-point temperature.The pressure of the water in the drum 16 of pressure sensor monitoring feed-water heater 14, and produce signal, review valve 56 in response to this signal open and close so that the saturation temperature in drum 16 remains on the level of expectation.Certainly, the temperature in the drum 16 should be in more than the acid dew-point temperature, but should not surpass this acid dew-point temperature approximately more than 15 ℉, and preferably should not surpass approximately 5 ℉, to obtain maximal efficiency in HRSGA.

Ip pump 28 and hp pump 30 will be by feed-water heater 14 heating but now since pressure improve and be sent to economizer 64 by excessively cold water, economizer 64 all is heated into higher temperature with the water of ip and hp what separate in pipe, and the water of ip and hp still keeps liquid phase.Economizer 64 provides the sensing unit of this heating.Preferably, in pipeline 2, be used for ip and hp steam around pipe by placed side by side so that each all meets with waste gas under identical temperature, but they also can be placed with one before another.Economizer 64 is discharged into aqueous water in two discharge pipe lines-ip discharge pipe line 66 and hp discharge pipe line 68.

Ip discharge pipe line 66 leads to the assembled unit 70 that plays ip evaporimeter and the effect of starting ip superheater, and it is placed the upstream from the waste gas streams of economizer 64.Ip assembled unit 70 produces saturated vapor and superheated steam after a while by draw heat from waste gas, and it leaves by ip pipeline 72.Hp discharge pipe line 68 leads to another hp economizer 74, and this hp economizer 74 is placed on the upstream that makes progress from ip assembled unit 70.Economizer 74 heats De Gengre with aqueous water, and by hp pipeline 76 with its discharge.

Ip pipeline 72 and hp pipeline 76 all are connected with ip superheater unit 78 with the hp evaporimeter of combination and they are carried out feeding, in this unit 78, have for hp water-steam and ip superheated steam separate around pipe.This unit 78 by the ip steam pipe line 80 that can lead to steam turbine give off middle pressure through overheated steam.This unit 78 also is sent to saturated vapor hp connecting line 82.It leads to hp superheater 84, and superheater 84 changes into superheated steam with saturated vapor.Superheater 84 gives off superheated steam by hp steam pipe line 86, and hp steam pipe line 86 can lead to steam turbine.

In the operation of HRSG A, hot waste gas enters shell 2 at entrance 4 places of shell 2, and Continuous Flow crosses shell 2 and arrive outlet 6, and it can be discharged in the atmosphere in outlet 6.Like this, gas successively runs into hp superheater 84, hp evaporimeter and ip and crosses hot cell 80, hp economizer 74, combination ip evaporimeter and superheater unit 70, lp superheater 50, hp and ip economizer 64, lp evaporimeter 34, and feed-water heater 14.Feedwater that can condensation under 100 ℉ or lower temperature enters HRSGA at condenser pump 10 places, and this condenser pump 10 forces feedwater to enter the drum 16 of feed-water heater 14 by water-supply line 12, herein its temperature moment raise (Fig. 2 A).In fact, the pressure reduction that pump 10 overcomes is minimum, can be 5psi or lower, because feed-water heater 14 under low pressure works, and rely on convection current so that water, and vapor recycle flows through feed-water heater 14.Bag 16 has comprised some aqueous waters, therefore also comprises some aqueous waters around pipe 18 below bag 16.And bag 16 is included in the saturated vapor of the top of water wherein, and exists the present pressure of steam to determine the temperature of aqueous water, and the temperature of this aqueous water is exactly steam and water saturation temperature under this pressure.This temperature is stablized constant, and it should surpass the acid dew-point temperature of waste gas, but preferably should not surpass approximately 5 ℉ of this acid dew-point temperature.Aqueous water in drum 16 flows through down-comer 20 and arrives around the bottom of pipe 18, by rising around pipe 18.Cross the heat of drawing around pipe at 18 o'clock at waste gas streams from waste gas a part of aqueous water is changed into saturated vapor, saturated vapor is along with remaining liter waterborne passes around pipe 18 and tedge 22.The two all enters drum 16.By the free convection evaporimeter, water is owing to convection current, natural property or be forced to circulate and pass feed-water heater 14, and remains on and stablize constant temperature.Water-supply line 12 is passed in the introduction feedwater that is introduced into drum 16, water is migrated out from wrapping 16, and the current that are transferred are through drainpipe 24, and residing low-pressure during with the temperature of the rising that surpasses the waste gas dew-point temperature and feed-water heater 14 work arrives three

pumps

26,28,30.In addition, raise although experienced the moment of temperature, introduce feedwater and in drum 16, make the saturated vapor condensation, prevent that thus steam is superfluous in bag 16.In any case steam can not overflow from wrapping 16; Just revert to simply saturated aqueous water.Feed-water heater 14 provides evaporation component, is used for heated feed water.

Lp pump 26 transmits water with higher pressure, so that it, passes the drum 36 that lp supply line 32 arrives lp evaporimeter 34 by again excessively cold, mixes with the water that temperature in drum 36 is higher herein, and the water that is positioned at the saturated vapor below has also occupied drum 36.These water leave drum 36 by down-comer 40, and down-comer 40 introduces these water around the bottom of managing 38.Be subject in the impact than the waste gas under pipe 18 higher temperature of feed-water heater 14, some water in pipe 38 water that will be under the elevated pressures of lp evaporimeter 34 change into saturated vapor, these saturated vapors and remaining water upwards flow into drum 36 together, and steam occupies the upper zone of bag 36.Because the pressure in evaporimeter 34 is higher, under the saturated vapor in its evaporation bag 36 and water are present in than the higher temperature of the water and steam in the feed-water heater 14.Similarly, circulate by free convection, but evaporimeter 34 also can obtain the auxiliary of pump.These saturated vapors flow through discharge pipe line 44 from drum 36 and arrive lp superheater 50.Be placed on the upstream of the waste gas streams that makes progress from lp evaporimeter 34, lp superheater 50 can be seen the temperature higher than lp evaporimeter 34, and in fact, temperature is high enough to saturated vapor is changed into superheated steam.These steam leave by lp steam pipe line 52.

In the lp saturated vapor some are left the drum 36 of lp evaporimeter 34, played the effect of reviewing steam, be used for being controlled at the pressure and temperature of saturated vapor of the drum 16 of feed-water heater 14, and the temperature of the aqueous water in drum 16 also be the same-and these be exactly the water around pipe 18 that circulation is passed down-comer 20 and entered feed-water heater 14.The vapor stream of reviewing of elevated pressures flows through and reviews pipeline 54, and it is by reviewing the drum 16 that is discharged into feed-water heater 14 under the pressure that valve 56 determines.This pressure is so that the acid dew-point temperature of the waste gas in a little higher than feed-water heater 14 of the steam in drum 16 and water saturation temperature.

28 pairs of ip pumps heated water in feed-water heater 14 transmits, and under than the higher middle pressure of the pressure that is produced by the lp pump it is emitted.Flow through combination economizer 64 through cold water, it is raised to higher temperature herein.Then it flows to combination ip evaporimeter and ip superheater unit 70, from leaving as superheated steam here.Experience further temperature through the ip of overheated steam in combination hp evaporimeter and ip superheater unit around pipe 78 places and raise, from being released to ip steam pipe line 86 here.Economizer 64 provides sensing unit for heated feed water.

Hp pump 30 also transmits heated water in feed-water heater 14, these water are introduced into combination economizer 64 under excessively cold state, herein its temperature rising, and the hp that from then on enters combination hp evaporimeter and ip superheater unit 78 is around pipe, and it is converted to saturated vapor herein.Saturated vapor flows into hp superheater 84, becomes superheated steam this its.These steam leave by hp steam pipe line 86.

Evaporation feed-water heater 14 and with the evaporative component of economizer 64 combination, be created in the waste gas that flows through these heat exchangers and flow through temperature contrast between their aqueous water by its sensing assembly.This temperature contrast is than wider with the temperature contrast that the feed-water heater of upstream economizer work obtains by traditional feed-water heater even Billy.For this consideration, the temperature of the water in feed-water heater 14 remains unchanged, not along with at the higher temperature of its end of waste gas streams upstream and raise.As a result, have relatively large temperature contrast in the end, upstream, more downstream part also is like this (Fig. 2 A).And water flows to economizer 64 with this lower temperature, therefore economizer 64 downstream end places around pipe, when entering waste gas streams, also can experience along those around obvious temperature contrast between the gas that pipe flows and the feedwater that enters them.

By way of example-and only as example-obtain from oil inflame and have the waste gas that acid dew-point temperature is 230 ℉, reach combination economizer 64 in shell 2 with the temperature of 600 ℉.Economizer 64 is drawn enough heats temperature being reduced to 400 ℉, and under this temperature, it flows into lp evaporimeter 34, and this lp evaporimeter 34 is drawn more heat, causes waste gas to flow to feed-water heater 14 at 300 ℉.Feed-water heater 14 is drawn more heat again from waste gas, be enough to its temperature is reduced to 245 ℉.And these waste gas leave shell 2 by exporting 4 under this temperature.Condenser pump 10 will feed water under 100 ℉ and deliver to the drum 16 of evaporimeter 14 with 500,000lb/hr, and this only needs enough pressure reduction to overcome lp evaporimeter 34 at bag 16 inner all pressure that produce, and it can be low to moderate 8psig.In fact, this pressure is enough to the steam in the drum 16 and water saturation temperature are remained on 235 ℉.And saturated water leaves bag 16 under this temperature, and enters around pipe 18, and it remains under 235 ℉ herein, and wherein some of while are converted to steam.Because the temperature of the water in pipe 18 does not raise, between water and waste gas, there is very large temperature contrast.Be under the above temperature of the acid dew-point temperature of waste gas, can't experience acid in they lip-deep condensations around pipe 18.Saturation water leaves drum 16 with 235 ℉ by discharge pipe line 24 equally,

inflow pump

26,28,30 under this temperature.The drum 36 of lp evaporimeter 34 introduced 100,000lb/hr by lp pump 26 under 235 ℉.Lp evaporimeter 34 changes into saturated vapor with water, under 350 ℉ by discharge pipe line 44 dischargings 10,000lb/hr.Ip pump 28 and hp pump 30 equally under 235 ℉ by

supply pipeline

60 and 62 with remaining with 400,000lb/hr is sent to combination economizer 64, it draws more heat with certain quite high efficient, this is because aqueous water is roughly entering economizer 64 under 235 ℉, producing the larger temperature difference between the waste gas at economizer downstream end place and feedwater, also is the same at farther upstream end.

Be equipped with feed-water heater 14 and the HRSG A of the economizer 64 of enclosing heats a large amount of feedwater, and the again circulation and the branch road that do not need the feed-water heater of traditional HRSG to utilize.In addition, feed-water heater 14 comes heated feed water by relatively little around pipe group 18, and this is because maintaining saturation temperature around the water of pipe in 18, and those in pipe 18 water and flow through between their waste gas and have relatively large temperature contrast.Water is because the effect of nature or forced convection cycles through around pipe 18, and therefore, condenser pump 10 does not need to overcome around pipe 18 otherwise may impose on any resistance of fluid.Owing to crossing around managing 18 o'clock at waste gas streams, can experience the obvious drop in temperature of waste gas around pipe 18, so they are highly efficient.When leaving feed-water heater 14, the aqueous water in heater 14 under the relatively low saturation temperature flows to economizer 64 by ip supply pipeline 60 and hp supply pipeline 62, therefore at the downstream end of economizer 64, has another sizable temperature difference.

On the contrary, the feed-water heater of traditional HRSG will have larger around the pipe group usually, and they are designed to the temperature difference draw heat by the less in waste gas streams, and those have added sizable resistance around pipe in feedwater flow.Condenser pump must overcome this resistance.In fact, because not recirculation in heater 14 itself, feed-water heater 4 does not need feedwater is heated to temperature high as traditional feed-water heater.And, at the temperature difference between the feedwater at pipe place and upstream economizer place and large unlike experiencing by feed-water heater 14 and economizer 64 (relatively Figure 1A and Fig. 2 A) of traditional feed-water heater.

The assembly of under the pressure that is produced by ip pump 28 and hp pump 30, working can from described in the preamble with accompanying drawing in describe different.And the parts with its role in the

pump

28 or 30 can be eliminated together, are created in the HRSG that transmits superheated steam under two pressure.Simultaneously, being supplied to the steam of reviewing of feedwater 14 bag 16 may be from the compressed steam source except the bag 36 of lp evaporimeter 34.Although the evaporative component of evaporimeter 34 and assembled

unit

70 and 80 is described and is described as natural circulating evaporator, they also can adopt has the auxiliary circulating evaporator of pump or even the form of the disposable evaporimeter that passes through.

Alternative HRSG B(Fig. 3) intimate identical with HRSG A, and similarly comprise identical feed-water heater 14 and lp evaporimeter 34.But three

pumps

26,28,30 are that the combination of another between feed-water heater 14 and lp evaporimeter 34 economizer 90 is supplied with in waste gas streams.Similarly aqueous water enters economizer 90 under the water saturation temperature by feed-water heater discharging, therefore the water in combination economizer 90 and flow through between the waste gas of economizer 90 and have sizable temperature difference (Fig. 3).This and contrast similar (Figure 1A and Fig. 3 A are compared) to the heating of feeding water among traditional HRSG.Therefore economizer 90 needs relative little of the pipe group in lp, ip and the hp water each.And feed-water heater 14 can comprise deaerator (deaerator) 92, and water-supply line 12 and review pipeline 54 and lead to this deaerator 92 is so that feedwater and review steam and flow into this deaerator 92.It is communicated with drum 16 by connecting line 94 then.

Claims

1. in a kind of HRSG, this HRSG is used for from flowing through described HRSG and have the waste gas draw heat of acid dew-point temperature, and is used for utilizing described heat will cross cold feedwater and changes into steam, and improvement comprises:

Feed-water heater, it is arranged in the stream of described waste gas, and described feed-water heater changes into saturated vapor and saturation water with the cold feedwater of the mistake of low temperature, and the temperature of described saturation water is more than the described acid dew-point temperature of described waste gas;

Feed pump, it receives the water from described feed-water heater, and the pressure of described water is raise; And

Economizer, it is arranged in waste gas streams with respect to the upstream of described feed-water heater, and is connected to described feed pump, is used for receiving the feedwater of pressure rising and the temperature of described feedwater being raise from described pump.

2. combination as claimed in claim 1, wherein, described feed-water heater comprises:

Drum, the cold feedwater of described mistake is introduced in this drum;

Around pipe, it is being positioned within described waste gas streams below the described drum, and is communicated with described drum in its bottom and upper end so that from the water circulation of described drum by around pipe, in pipe, some water in the described water are converted to saturated vapor described; And

Give water discharge pipeline, it connects described drum and described feed pump.

3. combination as claimed in claim 2, wherein, described drum is connected to reviews vapour source, is used for being controlled at the pressure of described drum.

4. combination as claimed in claim 2 further comprises:

Priming pump, it receives the subcooled water of low-temp low-pressure; And

Water-supply line, it connects the described bag of described priming pump and described feed-water heater, is used for introducing described bag from the feedwater of described priming pump.

5. combination as claimed in claim 4, further comprise evaporimeter, this evaporimeter comprises around pipe, should be arranged in described waste gas streams with respect to the described upstream around pipe of described feed-water heater around pipe, and be received in the feedwater through heating under the pressure of the rising that is produced by described feed pump, and produce saturated vapor;

And

The discharge of steam pipeline, saturated described steam leaves by this discharge of steam pipeline.

6. combination as claimed in claim 5, wherein, described evaporimeter further comprises drum, end and bottom are communicated with this drum around managing thereon for described evaporimeter described, so that pass through described around pipe from the water circulation of described drum, and some water wherein are transformed into saturated vapor, and this saturated vapor flows into described drum.

7. combination as claimed in claim 6 further comprises:

Review pipeline, it leads to the described drum of described feed-water heater, and is communicated with the described drum of described evaporimeter; And

Review valve, it is used for control and reviews the pressure of steam that pipeline is allowed to enter the described drum of described feed-water heater by described described review in the pipeline.

8. combination as claimed in claim 5, further comprise superheater, it is arranged in described around the upstream of pipe with respect to described evaporimeter of described waste gas streams, and is connected to the described discharge pipe line of described evaporimeter, is used for and will changes into superheated steam from the saturated vapor that described evaporimeter receives.

9. combination as claimed in claim 5, wherein, described evaporimeter described around pipe in described waste gas streams described economizer and described feed-water heater between pipe.

10. combination as claimed in claim 5, wherein, described economizer evaporimeter described in the described waste gas streams around pipe and described feed-water heater between pipe, and described feed pump forces to feed water and passes described economizer and enter described evaporimeter from described feed-water heater.

11. combination as claimed in claim 5 further comprises another evaporimeter, it is arranged in described waste gas streams with respect to the upstream of described economizer, is used for receiving the heated feedwater from described economizer, and converts it into saturated vapor.

12. combination as claimed in claim 1, wherein, described feed-water heater produces saturation water, and its temperature surpasses at the most 15 ℉ of described acid dew-point temperature.

13. a processing is used for the aqueous water that temperature and pressure raises is offered the evaporimeter that is positioned at waste gas streams, described waste gas streams has acid dew-point temperature, and described processing comprises:

Draw heat from described waste gas streams is will be heated to by excessively cold feedwater the saturation temperature more than described acid dew-point temperature, in order to saturated feedwater is provided;

The pressure of described saturated feedwater is raise, to produce the more feedwater of high pressure;

, from described waste gas streams, draw more heats and be heated to higher temperature with the feedwater with described more high pressure to produce the upstream of saturated feedwater at draw heat.

14. processing as claimed in claim 13 further comprises, in the upstream of draw heat with the feedwater of heating described more high pressure, draws more heats from described waste gas streams, changes into saturated vapor with the water with described more high pressure.

15. processing as claimed in claim 13, wherein, draw heat is comprised by excessively cold water with heating from described waste gas:

Introduced drum with described by excessively cold water;

Make from the water of described drum from circulation through being arranged in described waste gas streams around pipe so that some water in the described water change into saturated vapor, and saturated vapor and saturation water all flow into and occupy described drum.

16. processing as claimed in claim 15 further comprises: by controlling the pressure of the described steam in the described drum, be controlled at described saturated vapor in the described feed-water heater and the temperature of water.

17. processing as claimed in claim 15 further comprises:

Make the feedwater of described more high pressure change into the more saturated vapor of high pressure; And

By making saturation water described in the described drum become the saturated vapor of described more high pressure, control the temperature of the described saturation water in the described drum.

18. processing as claimed in claim 15, wherein, the described saturated vapor in described drum and the temperature of water surpass at the most 15 ℉ of described acid dew-point temperature.