KR101659527B1 - Heat recovery module - Google Patents

Abstract

There is disclosed a module for recovering the heat of an exhaust gas from a steam generator comprising an exhaust gas outlet conduit forming a flow path of the exhaust gas from the exhaust outlet of the steam generator to the exhaust gas conduit connection; A first exhaust conduit defining a flow path of the exhaust gas from the connection to the first air heater; And a second exhaust conduit from the junction to form a flow path of exhaust gas from the junction to at least one high pressure and at least one low pressure economizer process liquid economizer. Also disclosed is a steam generator using the module, a method of implementing the flow principle included in the module, and a method of incorporating the module into the steam generator, in particular, by modification.

Description

Heat recovery module {HEAT RECOVERY MODULE}

The present invention relates to a module for recovering heat from an exhaust gas in a steam generating process, including a steam generator, such as a boiler, which can extract steam from the inner end of the turbine to heat the condensate and feedwater to increase cycle efficiency A condensate and a feedwater heating system and a steam turbine generator. The present invention also relates to a steam generation system and method thereof.

In the steam generation process, there are generally one or more steam generators that can be burned by various types of fuel, such as oil, gas, biomass, and coal, and the boiler is one example. Boilers for steam generation are well known and may form part of a power plant that uses steam to drive one or more steam turbine generators.

From the steam generator (s), exhaust gas, which typically heats the combustion air, is discharged. The fuel and premixed air before ignition are generally referred to as "primary air ", and the air to support post-ignition combustion is generally referred to as" secondary air ". In a coal or biomass fired boiler, the primary air can form a separate stream because its pressure is much higher than that of the secondary air. Combustion air, including primary air and secondary air, can be heated (preheated) using reconditioning air heaters.

Typically, the primary and secondary air streams are heated by heat exchange with the offgas stream in a gas-to-air heat exchanger, such as a regeneration gas air heater. However, the heat capacity of the flue-gas is much higher than the heat capacity of the air in the conventional arrangement of gas-to-air heat exchangers, making the heat exchange process inefficient.

According to a first aspect of the present invention there is provided a module for recovering heat from an exhaust gas from a steam generator in a steam generation process,

(a) an exhaust gas outlet conduit forming a flow path of the exhaust gas from the exhaust gas outlet of the steam generator to the exhaust conduit first connection;

(b) a first exhaust conduit defining a first flow path of the exhaust gas from the first connection to the first air heater; And

(c) a second flue gas conduit that forms a second flow path of flue-gas from the first connection in parallel with the first flue gas conduit to at least two process liquid economizers comprising one or more high-pressure economizers and one or more low-pressure economizers; Lt; / RTI >

By using the process liquid economizer including the one or more high pressure economizers and the one or more low pressure economizers, the air flow in the first air heater and the heat capacity of the process liquid and the flue gas in the process liquid economizer can be best matched. The backend temperature can be significantly reduced. It also reduces the energy loss of the heat transfer process. The efficiency of the entire steam generation process is increased.

The first air heater may include one or more first air heaters in series, in parallel, or both. Preferably, the first air heater includes at least a regeneration gas air heater capable of heating one or more secondary air streams, one or more primary air streams, or both, such as all of them. This may include a multi-sector regenerative air heater.

Regeneration air heaters are compact and efficient gas-to-air heat exchangers for recovering heat from flue-gases. The total weight and volume of air heaters can be minimized by using a reconditioning air heater.

In one embodiment of the present invention, the first air heater at least comprises a gas secondary air heater for the secondary air stream, which is preferably provided in a steam generator, such as a boiler, in a steam generating process. In general, it is desirable to raise the temperature of the secondary air to a temperature suitable for the combustion process, which may be higher than 200 ° C or higher than 300 ° C, as is known in the art.

Each of the high pressure and low pressure process liquid economizers may include one or more economizers in series, in parallel, or both. Embodiments of the invention as described below may be applied to a single process liquid economizer, or each of a plurality of process liquid economizers, or may vary across a plurality of process liquid economizers.

According to the present invention, the heat recovery module comprises at least one high pressure economizer and at least one low pressure economizer. The terms "high pressure" and "low pressure" are known to those skilled in the art in the field of steam generation processes, particularly including steam generators such as boilers. Generally, these are related to the relative pressures of the streams upstream and downstream, respectively, from the feed pump.

The process liquid may be provided in one or more streams. A plurality of process liquid streams may be provided in series, in parallel, or both, and may alternatively be provided from a single source, or from a plurality of same or different sources. The characteristics and composition of each of these streams may be the same or different.

The process stream may be provided as one or more process liquid circuits, alternatively, as a plurality of discrete circuits, separated or connected, and for heat exchange between the process liquid stream and any primary air stream of the steam generation process, The circuit is selectively delivered to any individual primary air heat exchanger.

The process liquid may be any liquid or combination of liquids usable for heat exchange, including water, ammonia, alcohol, hydrocarbons, and the like. Preferably, the process liquid is entirely or substantially water, and optionally comprises one or more additives or other minor components known in the art.

In another embodiment of the present invention, the process liquid is a water supply for a steam generator. Such a steam generator may optionally be a boiler comprising one or more boilers, and optionally includes an integrated steam generator economizer as is known in the art. By using a feed water as the process liquid, heat can be directly transferred from the flue-gas to the feed water, which minimizes the energy loss of the heat transfer process.

This feedwater may be provided directly or indirectly from a feed stream that is processed by one or more steam generators of the steam generation process of the present invention. Preferably, a portion of the feed stream is provided as a process liquid of the present invention. Some of which may be provided as a full feed stream or preferably as a slip stream of a feed water stream and generally the slip stream is a small portion of the full feed stream.

According to another embodiment of the present invention, the feed water is provided from a feed stream in a steam generation process between a steam condenser and a steam generator economizer.

Thus, the module of the present invention may further include one or more first process liquid conduits to form one or more flow paths for directing the process liquid from the feed stream to the process liquid economizer.

In addition, the module of the present invention may further include one or more second process liquid conduits to form one or more flow paths for directing the process liquid from the process liquid economizer to the feed stream.

According to another embodiment of the present invention, the flue gas first conduit connection is used as a first and a second flue gas path to best match the heat capacity of the air flow in the first air heater and the heat capacity of the second flue gas path And a proportional damper set for dividing the flue gas in the flue gas.

In addition, the module of the present invention

(d) a third exhaust conduit defining a flow path of the exhaust gas from the first air heater to the second connection;

(e) a fourth exhaust gas conduit forming a flow path of the exhaust gas from the process liquid economizer to the second connection; And

(f) a fifth exhaust conduit forming a flow path of the exhaust gas from the second connection.

In a possible second aspect of the present invention, the first air heater is a secondary air heater, and the present invention includes one or more primary air streams including one or more process liquid heat exchangers for exchanging heat between the primary air stream and the process liquid And further includes a heater.

By heating the primary air stream with the process liquid rather than the hot flue gas stream, the problem of the primary air leaking from the regeneration gas air heater can be avoided and the heat exchange can be more reliably controlled.

As used herein, the term "primary air stream" may include one or more primary air streams in series, in parallel, or both. Embodiments of the present invention as described below may be applied to a single primary air stream, or each of a plurality of primary air streams, or may vary across a plurality of primary air streams. Thus, although the present invention has been described with reference to a single primary air stream, the present invention is not so limited.

The primary air stream may comprise any combination of air, regeneration gas, or one or more other components such as a quasi-oxygen or pure oxygen stream optionally added such that the ratio is 0 to 100%. The requirement of the primary air stream is to at least partially assist the combustion support, as well as the supply and / or delivery of fuel to the steam generator.

If the primary air stream comprises two or more primary air streams, each primary air stream may be, but is not limited to, the same, including flow rate, flow rate, temperature, pressure, oxygen content, and regeneration gas content Or may include different properties and / or compositions.

If the primary air stream comprises two or more primary air streams, each primary air stream may be heated by a different number of primary heat exchangers, either the same or different.

If the primary air stream comprises two or more primary air streams, two or more of the air streams may be, before or after their intended use or destination, in accordance with the present invention Can be integrated after heating.

Where the primary air stream comprises two or more streams of primary air streams, the primary air streams may be delivered to the steam generator individually and / or in any combination.

In one embodiment, a plurality of primary air streams are provided, each primary air stream being a stream for providing and / or transporting individual fuel streams to a steam generator, such as a plurality of equalized fuel grinders, The crusher delivers the individual fuel streams to the boiler. In this way, the individual control of each primary air stream can provide greater control flexibility in the overall fuel delivery, delivery, and delivery to the steam generator.

The system may include two or more primary heat exchangers, either in series, parallel, or both, that provide heat exchange with one or more primary air streams in series, in parallel, or both , The system can include any combination of any number of primary air streams and primary air heat exchangers.

In one embodiment of the invention, the primary air heat exchanger (s) comprise at least one high pressure heat exchanger and at least one low pressure heat exchanger. The terms "high pressure" and "low pressure" are known to those skilled in the art, particularly in the field of steam generation processes, including steam generators such as boilers and feed heating / heat recovery systems.

The process liquid may be provided in one or more streams. A plurality of process fluid streams may be provided in series, in parallel, or both, and may optionally be provided from a single source, or from multiple sources. Optionally, the process stream may also be provided as one or more process liquid circuits, alternatively, as a plurality of discrete circuits, separated and connected, and for heat exchange between the process liquid stream and the primary air stream, Are selectively delivered to separate primary air heat exchangers.

Each process liquid stream is delivered to an individual primary air heat exchanger.

Because the flow of process liquid can be easily controlled, the system of the present invention can better control the heat of the primary air stream. There is no need to temper the air source supply into the primary air stream to achieve the correct temperature of the primary air stream prior to use in the steam generation process. Preferably, a gas-to-air heater of the primary air stream is not required.

In a possible embodiment, the primary air heat exchanger (s) comprises one or more high pressure heat exchangers and one or more low pressure heat exchangers. The terms "high pressure" and "low pressure" are known to correspond to the pressure downstream or upstream of the feed pump (s), respectively.

In coal-fired steam generators or boilers, coal is typically pulverized in one or more polishers before being used in boilers.

In accordance with another embodiment of the present invention, the primary air stream is heated by the primary air heat exchanger (s) and then delivered to one or more mills, typically two or more mills. Preferably, each primary air stream is delivered to a separate mill.

Preferably, each primary air stream is separately heated by a separate primary air heat exchanger (s).

The modules of the present invention may be provided integrally as part of the steam generation process or may be added to existing steam generation processes by being installed as freshly installed in the path of the exhaust gas discharged from an existing steam generator such as a boiler .

According to a third aspect of the present invention there is provided a steam generation system comprising a steam generator such as a flue gas heat recovery module and a boiler as defined herein. Preferably, the steam generation system comprises one or more steam generation processes as defined herein.

Preferably, the steam generating system comprises one or more first flow paths for directing the process liquid from the steam generator feed stream to the process liquid economizer, one for directing the process liquid from the process liquid economizer to the steam generator feed stream, Or more of the second flow path.

Further, in the steam generating system of the present invention,

(d) a third exhaust conduit defining a flow path of the exhaust gas from the first air heater to the second connection;

(e) a fourth exhaust gas conduit forming a flow path of the exhaust gas from the process liquid economizer to the second connection;

(f) a fifth exhaust conduit forming a flow path of the exhaust gas from the second connection; And

(g) a downstream process fluid heat exchanger in the path of the fifth conduit.

The downstream process fluid heat exchanger is capable of direct or indirect heat transfer to one or more streams of the steam generation process, particularly to one or more inlet air streams that require a temperature higher than ambient temperature, Can be used. This inlet air stream may include the primary air stream, the secondary air stream, or both, either separately or as an integrated stream, such as before separation into the primary and secondary air streams. This can provide additional heat recovery from the flue gas, thus ensuring greater efficiency of the available energy in the steam generation process and utilization of more heat.

Thus, in accordance with the present invention, there is provided a system and method for controlling a downstream process fluid to heat any of the primary air flow, any or the secondary air flow, There is provided a steam generating system for recovering heat from an exhaust gas of a steam generator including a heat recovery module according to one aspect of the present invention.

Accordingly, the present invention can provide a steam generating system for recovering heat from the exhaust gas of a steam generator in a steam generating process,

(a) an exhaust gas outlet conduit forming a flow path of the exhaust gas from the exhaust gas outlet of the steam generator to the exhaust conduit first connection;

(b) a first exhaust conduit defining a first flow path of the exhaust gas from the first connection to the first air heater;

(c) a second exhaust conduit defining a second flow path of the exhaust gas from the first connection to the at least one low pressure and at least one high pressure process liquid economizer in parallel with the first exhaust conduit;

(d) a third exhaust conduit defining a flow path of the exhaust gas from the first air heater to the second connection;

(e) a fourth exhaust gas conduit forming a flow path of the exhaust gas from the process liquid economizer to the second connection;

(f) a fifth exhaust conduit forming a flow path of the exhaust gas from the second connection; And

(g) a downstream process fluid stream in the path of the fifth conduit to heat the downstream process fluid to heat either the optional or primary air flow, the optional or secondary air flow, or both in the steam generation system. Exchanger.

According to a fourth aspect of the present invention, there is provided a heat recovery method for recovering heat from an exhaust gas of a steam generator,

(I) dividing the exhaust gas discharged from the steam generator into two streams;

(Ii) supplying a first stream to a first air heater;

(Iii) supplying a second stream to at least two process liquid economizers comprising at least one low pressure and at least one high pressure process liquid economizer.

Preferably, the heat recovery method uses a heat recovery module as defined herein. In the heat recovery method, preferably, the first air heater is a regeneration gas air heater.

Preferably, the first air heater is a secondary air heater, and the method further comprises the steps of: (a) passing one or more primary air heat exchangers to exchange heat from the process liquid to the primary air stream of the primary air heat exchanger And passing the process liquid.

Preferably, the method of heating a primary air stream in accordance with the present invention comprises heating the primary air stream using an embodiment of the system as described herein.

The heat recovery method may include a first air heater and a process liquid economizer to form an integrated stream that sequentially or indirectly sequentially exchanges heat with either the primary air flow, the secondary air flow, And a step of integrating the stream.

Preferably, the method for recovering heat from the flue-gas of the steam generator according to the present invention comprises the step of using a steam generating system as defined herein.

According to a fifth aspect of the present invention there is provided a method of modifying a heat recovery system for a steam generator having one or more air heaters to supply an exhaust stream, said method comprising: And providing at least one low pressure and at least one high pressure process liquid economizer.

Particularly, the fifth aspect of the present invention includes a post-sales transformation method of an existing plant. The present invention is particularly suitable for modification. Many thermal power plants suffer from high back-end temperatures (ie high exhaust gas temperatures at the air heater outlet), especially when the fuel content changes significantly. Nearly all thermal power plants operate at high back-end temperatures in the summer. By adding a slipstream economizer of the appropriate size in parallel with the air heater, the deformation can be made without replacing expensive prime facilities such as FDF, IDF, AH SAH and the like. The heat capacity of the boiler flue gas will better match the heat capacity of the combustion air and the slipstream feed stream in the economisers. The backend temperature will be significantly lower and the energy loss of the heat transfer process will be minimized. Thus, the cycle efficiency is improved. Modifications can be made to plants with or without steam / water air heaters.

Steam or water air heaters are installed in most existing plants. These are heat exchangers for preheating the air stream before entering the gas air heater. With the help of steam / water air heaters and relatively large economizers, the back-end temperature can be lowered to improve boiler thermal efficiency.

Thus, preferably, the method includes a method for retrofitting a module according to the first aspect of the present invention to a heat recovery system of a steam generator having one or more air heaters to supply an exhaust stream.

In another aspect, the present invention includes a heat recovery system of a steam generator having one or more air heaters to supply an exhaust stream with such newly installed modules.

The present invention includes all combinations of the various embodiments or inventive aspects described herein. It is to be understood that any and all embodiments of the invention may be considered in conjunction with any other embodiment to illustrate further embodiments of the invention. In addition, any component of an embodiment may be combined with any and all other components of any other embodiment to describe additional embodiments.

Hereinafter, embodiments of the present invention will be described by way of example only with reference to the accompanying drawings.
1 is a view illustrating a first structure of a heat recovery module according to an embodiment of the present invention in a steam generation process,
FIG. 2 is a view including the first structure shown in FIG. 1 in the extended steam generating process,
FIG. 3 is a view including a steam generation system according to another embodiment of the present invention and the heat recovery module of FIG. 1. FIG.
For the sake of clarity, not only the lines but also the steam delivered to that line are given a single reference number.

Referring to the drawings, Figure 1 shows a first structure (A) of a heat recovery module for use in a steam generation process. In the first structure (A), the steam generating process comprises a steam generator, which is a boiler (4). The boiler 4 may comprise a plurality of inlets and outlets through which a plurality of streams pass, in particular a feed stream 2 and a steam outlet. Most of these inlets, outlets, and streams are not shown in FIG. 1 for clarity.

The combustion process in the boiler 4 produces an exhaust flue gas which exits the flue gas outlet conduit 14 through the flue gas outlet 13 and exits the internal economizer in the boiler 4 The temperature is reduced inside the boiler 4 to generate steam before. The exhaust gas outlet conduit 14 extends to a flue gas conduit first connection 16 which is connected to the first exhaust path of the first flue gas conduit 18 and the second flue gas conduit of the second flue gas conduit 20, And a proportional damper set for dividing the exhaust gas in use in the exhaust gas path.

The first exhaust gas conduit 18 delivers its flue gas to a first air heater, wherein in the first configuration A of FIG. 1, the first air heater has one or more air streams Is a regeneration gas air heater. For example, the first air heater may be a secondary air preheater such as the regeneration gas secondary air heater 22. [ In the secondary air heater 22, the thermal energy of the exhaust gas is exchanged with the secondary air stream 24 in a manner known in the art, so that a cold exhaust gas from the appropriate outlet (the secondary air heater 22) To the third exhaust gas conduit 26 (which forms the flow path of the exhaust gas from the first connection 28 to the second connection 28), and for direct use in the combustion of the fuel in the boiler 4 in a manner known in the art Thereby providing the boiler 4 with a high temperature secondary air stream 30 that can be indirectly delivered.

Additionally and / or alternatively, the first air heater of FIG. 1 may provide heat to the one or more other air streams indicated in FIG. 1 by line 24a. This may include one or more primary air streams that can be used in a coal fired boiler. Accordingly, the first air heater may be a multi-sector air heater for heating both the primary air and the secondary air. Alternatively, at the outlet of the air heater, the combustion air can be divided into primary and secondary air streams. A high temperature primary air fan may be installed to increase the primary air pressure.

The flue gas of the second flue gas conduit 20 forms a second flow path of the flue gas from the first connection 16 in parallel with the first flue gas conduit 18 to one or more process liquid economizers. 1 (A), a high pressure (process liquid) economizer 32 and a subsequent serial low pressure (process liquid) economizer 34 are shown.

The high pressure and low pressure economizers (32, 34) can exchange heat in the exhaust gas from the boiler (4) with one or more process liquids. 1, the high pressure economizer 32 is provided with a process liquid as a first process fluid stream 36. The first process fluid stream 36 is a high pressure, The process liquid of the first process liquid stream 36 may be any suitable liquid available in the steam generation process. Preferably, the process liquid of the first process liquid stream 36 is a slip stream of the main feed stream 2, which is later processed by the steam generator of the steam generation process, which is the coal combustion boiler 4 . This will be described later in more detail with reference to FIG.

The first process liquid stream 36 may extract heat from the exhaust gas of the second exhaust gas conduit 20 to provide a hot first process liquid stream 38 and a cold exhaust gas stream 40, The cold flue gas stream 40 is delivered to the low pressure economizer 34 via a suitable inlet.

In a similar manner, the cold exhaust stream 40 is delivered to the low pressure economizer 34 through a suitable inlet to provide a second cold process stream 44, which is hot, through a suitable outlet Which may provide heat to the second process fluid stream 42 which is connected to a fourth exhaust gas conduit 46 which forms a flow path of the exhaust gas from the low pressure economizer 34 to the second connection 28, Lt; / RTI >

There is a fifth exhaust conduit 48 forming a flow path of the exhaust gas from the second connection 28.

It is a feature of the present invention that the exhaust gas distribution in the exhaust outlet conduit 14 between the first exhaust conduit 18 and the second exhaust conduit 20 is suitably controlled so that high pressure and low pressure The process liquid economizer being the economizer 32,34 and the heat capacity of the air flow in the first air heater which is the regeneration gas secondary air heater 22 in the first structure A of Figure 1 and the heat capacity of the first and second The heat capacity of the exhaust gas in the exhaust gas path can be best matched. In this way, improved cycle efficiency can be achieved by minimizing the energy loss of the heat transfer process with a minimized Log Mean Temperature Difference (LMTD) to recover heat from the flue gas of the boiler 4.

In at least a portion of the exhaust gas from the steam generator, the use of a process liquid, such as water in the process liquid economizer, rather than air in the gas-to-air heat exchanger provides significant advantages. These advantages include the transport of process liquids, such as those around the circuit, which can be carried out with minimal pressure loss per distance, even when using small pipes. Another advantage is that by carefully selecting and controlling the temperature difference and the flow of water in the first air heater and the process liquid economizer (s), the heat exchange for the process liquid can be optimized (and hence the LMTD can be minimized There is a point.

In addition, since the specific heat capacity of a liquid such as water is much higher than the specific heat capacity of a gas such as air, the flow of process liquid, such as water, can be significantly reduced while still providing the same amount of heat exchange from the flue gas stream.

In particular, the use of a feedwater as process liquid for the process liquid economizer in the first structure (A) of FIG. 1 is achieved by providing first and second process fluid streams 36, 42 for the slip stream (s) By carefully selecting the flows and tap points used to provide and directly delivering heat to the feedwater, the efficiency of the thermal energy utilization of the flue gas is improved.

The above-described structure is particularly suitable for retrofitting existing plants.

The slipstream economizer may be sized to achieve a minimized backend temperature based on the sulfur content of the fuel when burning low moisture coal in summer. A gas damper may be installed in the bypass gas duct. Bypass gas is reduced in burning high water coal and / or in winter so that the minimized back-end temperature can be maintained based on the sulfur content of the fuel irrespective of the moisture of the fuel and the ambient temperature.

In order to further lower the backend temperature of the gas air heater while maintaining the AH cold end metal temperature above a certain value to prevent corrosion caused by the acid condensate, a larger slip stream economizer and steam or water air With the aid of the heater, more exhaust gas can be bypassed to the slipstream economizer.

Cryogenic turbine bleed steam or water feed can be used to heat the combustion air in the water / steam air heater. One or two slipstream economizers using high and low pressure boiler feeds as refrigerant can be arranged. The flow and temperature of the slip stream economizer and the refrigerant or the on-stream for the water / steam air heater must be carefully selected to ensure the most efficient energy recovery as well as cost efficiency.

Boiler efficiency is very sensitive to back-end flue-gas temperatures. The advantages of the above described modifications are very important. However, by introducing a slipstream economizer, the amount of turbine bleed steam must be reduced. Due to the use of a water / steam air heater, some bleed vapor reduction will be offset. The negative impact on the turbine heat rate caused by the slipstream economizer is partially compensated for by the use of the water / steam air heater. In general, improving overall plant efficiency is still important.

Changes to existing major facilities such as FDF, IDF, AH, etc. are not required. The major expense would be for this additional slipstream economizer. There is flexibility in sizing the slip stream economizer. Sizing can be optimized taking into account such variables as budget, fuel price and plant operating conditions.

FIG. 2 is a view showing a first structure (A) of FIG. 1 having a detailed configuration of a steam generating system using a coal combustion boiler, in particular, a detailed configuration of the primary air stream and the water feed stream.

The coal for the boiler 4 of FIG. 2 is supplied as a coal stream 6. Typically, the coal stream 6 is pulverized in one or more pulverizers 8, typically 4 to 6 pulverizers, and provided to the boiler 4 as a pulverized coal stream 10. The primary air stream (12) is provided in the one or more mills (8).

The path of the primary air stream 12 shown in Figure 2 includes a primary air stream 12 to provide a hot primary stream 12a and a cold primary heat stream 54 through a suitable outlet. There is shown a first low pressure heat exchanger 50 that is capable of exchanging heat between the first heat stream 52 and the first heat stream 52. The hot primary air stream 12a is delivered to the high pressure primary air heat exchanger 55 and further heated by the second heating stream 56. The high pressure primary air heat exchanger 55 is connected to another heated primary air stream 12b that can be delivered to the one or more mills 8 and a second outlet .

The first and second heating streams 52 and 56 may be provided from the same or separate sources and may be provided as part of the same or separate circuits. For example, the first heating stream 52 may be provided from a deaerator exhaust stream, and the secondary heating stream may be provided, for example, from a feed slipstream following a high pressure water heater. In a non-limiting example of the present invention, the low temperature first and second heating streams 54,58 may be formed as at least a portion of the first and second process fluid streams 36,42, Directly or indirectly.

2 also shows a water feed stream 2 having a first slip stream 60 at an appropriate first water feed connection 62 at one or more feed water heaters or portions thereof known in the art, As shown in FIG. The first slip stream 60 may be used to directly or indirectly provide the process liquid to the second process liquid stream 42 using any suitable selectivity and the remaining feed stream 64 may be used to provide the first process stream And follows the connecting portion 62.

Figure 2 shows the regression of the hot second process liquid stream 44 as the first regression stream 66 delivered to the residual feed stream 64. The recombined feed stream 68 may be subjected to one or more processes, such as heating, pressurizing, or both, to provide a processed feed stream 70, and the second feed slip stream 72 May be provided through the second water supply connection portion 74 in the same manner as described above with respect to the first water supply connection portion 62.

In the same manner as described above, the second slip stream 72 can be used to directly or indirectly provide the process liquid to the first process liquid stream 36 using any suitable selectivity, (76) follows the second water supply connection part (74). Figure 2 shows the regression of the first process liquid stream 38 at a high temperature as the second regression stream 78 delivered to the residual feed stream 76. The recombined feed stream 80 may then be passed directly or indirectly to the boiler 4.

FIG. 2 shows, in addition to the appropriate configuration for providing the first and second process liquid streams 36, 42 from the feed stream 2, optionally with conduits and circuits used for the process liquid economizer, And an appropriate configuration for using the first and second heating streams 56, 52 to provide heat to the stream 12.

FIG. 3 is a view showing the structures of FIGS. 1 and 2 together with another steam generating system according to another embodiment of the present invention.

3, the exhaust gas of the fifth exhaust conduit 48 from the second connection 28 passes through an electrostatic precipitator (ESP) 82 and an induction fan 84 and continues through a suitable inlet to the fifth conduit 48 To the downstream process fluid heat exchanger (86) in the path of the downstream process fluid heat exchanger (86). The downstream process fluid heat exchanger 86 may extract any residual available thermal energy from the flue gas with the process fluid downstream of the first process circuit 100.

The first process circuit 100 is coupled to the downstream process fluid heat exchanger 86 through a suitable inlet to provide a hot downstream process fluid stream 104 to the second fluid conduit 104 through a suitable outlet The process fluid in at least the first downstream process fluid conduit 102. In the first circuit connection 106, the hot downstream process fluid stream 104 is divided by a suitable controller into a secondary air heating stream 108 and a primary air heating stream 110 in the range of 0-100% .

The secondary air heating stream 108 is passed through a suitable inlet to the secondary air preheat exchanger 112 to provide heat exchange with the initial secondary air stream 90 to provide a regeneration gas secondary air heater 22 Provides some preheating for the secondary air prior to subsequent heating of the secondary air stream 24 by the secondary air stream 24.

Likewise, the primary air heating stream 110 may provide some preheating for the initial primary air stream 92 in the primary air preheat exchanger 114 (after passing through the primary air fan 94) Thereby providing a primary air stream 12 that is subsequently heated by the first and second air heat exchangers 50,55 as described above.

The downstream process fluid of the downstream process fluid circuit 100 can be any suitable liquid, gas, or combination thereof, and is generally low pressure, and is typically circulated in the circuit 100 by one or more suitable circulating pumps .

The primary and secondary air preheat exchangers 112 and 114 provide low temperature regression streams 116 and 118, respectively, which may be recombined to provide the process fluid of the first downstream process fluid conduit 102. The downstream process fluid heat exchanger 86 provides a cold exhaust gas stream 88.

The initial primary air stream 92 and the secondary air stream 90 may be provided from a single air source stream 94 prior to being split by a suitable controller.

In a first alternative, the hot downstream process fluid stream (104) of the second fluid conduit (104) is separated from the single air source stream (94) to heat these air before the primary air and the secondary air are split. Passes through a heat exchanger on.

The downstream process fluid circuit 100 provides for some preheating of the primary and secondary air streams to increase utilization of the available thermal energy in the exhaust gas to maximize the efficiency of the steam generation system shown in FIG. do.

Claims (20)

A module for recovering heat from an exhaust gas from a steam generator in a steam generating process,
(a) an exhaust gas outlet conduit forming a flow path of the exhaust gas from the exhaust gas outlet of the steam generator to the exhaust conduit first connection;
(b) a first exhaust conduit defining a first flow path of exhaust gas from the first connection to the first air heater, the first air heater comprising a secondary air heater, A first exhaust conduit, comprising a gas air heater; And
(c) a second exhaust conduit from the first connection to form a second flow path of the exhaust gas in parallel with the first exhaust conduit to at least two process liquid economizers comprising at least one high pressure economizer and at least one low pressure economizer In addition,
The flue gas first conduit connection portion is configured to best match the heat capacity of the air flow in the first air heater and the heat capacity of the second flue gas path and to reduce the back-end temperature of the flue- A module comprising a proportional damper set dividing flue gas. The method according to claim 1,
Further comprising at least one primary air heater comprising at least one process liquid heat exchanger for exchanging heat between the primary air stream and the process liquid. The method according to claim 1,
Wherein the process liquid is water. The method of claim 3,
Wherein the process liquid is a water supply for the steam generator. 5. The method of claim 4,
Wherein the process liquid is one or more slipstreams of a feed stream being processed by a steam generator of a steam generation process. 6. The method of claim 5,
A module comprising one or more first process liquid conduits to form one or more flow paths for transferring process liquid from a feed stream to a process liquid economizer. 6. The method of claim 5,
And one or more second process liquid conduits to form one or more flow paths for transferring process liquid from the process liquid economizer to the feed stream. A steam generating system comprising an exhaust gas heat recovery module according to claim 1 and a steam generator. 9. The method of claim 8,
One or more first flow paths for transferring the process liquid from the steam generator feed stream to the process liquid economizer (s), and one or more second flow paths for transferring the process liquid from the process liquid economizer to the steam generator feed stream A steam generating system comprising a flow path. 9. The method of claim 8,
(d) a third exhaust conduit defining a flow path of the exhaust gas from the first air heater to the second connection;
(e) a fourth exhaust gas conduit forming a flow path of the exhaust gas from the process liquid economizer to the second connection;
(f) a fifth exhaust conduit forming a flow path of the exhaust gas from the second connection; And
(g) a downstream process fluid heat exchanger in the path of said fifth conduit. 11. The method of claim 10,
Further comprising the use of the downstream process fluid heat exchanger to provide heat to the primary air flow, the secondary air flow, or both. A heat recovery method for recovering heat from an exhaust gas of a steam generator,
(I) dividing the exhaust gas discharged from the steam generator into two streams;
(Ii) supplying a first stream to a first air heater, wherein the first air heater includes a secondary air heater, and the first air heater includes at least a regeneration gas air heater. Supplying the air to the first air heater;
(Iii) supplying a second stream to at least two process liquid economizers comprising at least one low pressure economizer and at least one high pressure economizer,
A proportional damper set is used to match the heat capacity of the air flow in the first air heater with the heat capacity of the second exhaust path and to allow the back-end temperature of the exhaust gas to be lowered, Heat recovery method for dividing. 13. The method of claim 12,
A heat recovery method using the module formed in claim 1. 13. The method of claim 12,
Further comprising integrating the first and second streams to form an integrated stream after the first air heater and the process liquid economizer, and wherein the integrated stream then includes a primary air stream, a secondary air stream, And heat exchange is performed with the heat exchange method. 13. The method of claim 12,
The method further comprises passing the process liquid through one or more primary air heat exchangers to exchange heat from the process liquid into the primary air stream of the primary air heat exchanger (s). 1. A method of modifying a heat recovery system for a steam generator having one or more air heaters to supply a primary flue gas stream,
Providing at least one low pressure and at least one high pressure process liquid economizer in fluid parallel with the air heater (s)
A method as claimed in any one of the preceding claims, wherein the method is performed as a method for modifying an existing plant to newly install a module defined in claim 1. delete delete delete delete

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