Patent Description:
A gas turbine is a power engine that mixes air compressed by a compressor with fuel for combustion and rotates a turbine with hot gas produced by the combustion. The gas turbine is used to drive a generator, an aircraft, a ship, a train, etc..

A heat recovery steam generator (HRSG) is an energy recovery device that recovers heat from a hot gas stream to produce steam that is usable to drive a steam turbine (combined cycle). The HRSG typically includes four main components: an economizer, an evaporator, a superheater and a preheater.

In particular, a natural circulation HRSG includes piping to facilitate a proper rate of circulation within an evaporator tube, as well as evaporator heating surfaces and drums. A once-through HRSG includes a once-through evaporator that replaces a natural circulation component, thereby providing higher facility efficiency on site and further assisting in extending HRSG life in the absence of thick wall drums. A steam generator according to the preamble of claim <NUM> is disclosed in <CIT>.

In the case of supercritical pressure vertical once-through HRSGs, it is difficult to ensure structural stability due to severe thermal expansion of an outlet head of a final superheater. Heating and thermal expansion of the outlet head by steam heated to a high temperature distorts tube arrangement and concentrates thermal stress, resulting in a high risk of breakage.

Aspects of one or more exemplary embodiments provide a once-through heat exchanger, a heat recovery steam generator, and a combined power generation system including the same, which are capable of minimizing damage caused by thermal expansion.

Additional aspects will be set forth in part in the description which follows and, in part, will become apparent from the description, or may be learned by practice of the exemplary embodiments.

According to the invention, there is provided a heat exchanger according claim <NUM>, in particular a once-through heat exchanger, that includes a tube stack including a plurality of tubes, a plurality of heads connected to the tube stack and configured to accommodate heated steam, a connector module configured to connect the tubes and the heads and including a plurality of tube connectors, a manifold connected to the heads and configured to accommodate heated steam, and a plurality of link pipes configured to connect the heads and the manifold, and the connector module includes a first tube connector and a second tube connector having different shapes.

The heads are spaced at different distances from the manifold.

The heads adjacent to each other in a longitudinal direction of the manifold may be spaced at different distances from the manifold.

The first tube connector may include a first connection part connected to associated ones of the heads. The second tube connector may include a second connection part connected to associated ones of the heads. The first connection part may have a smaller length than the second connection part.

The first connection part and the second connection part may be formed in parallel.

The first tube connector may further include a first extension part extending in a longitudinal direction of the link pipes from the first connection part. The first tube connector may further include a first intermediate part extending in a longitudinal direction of the first connection part from the first extension part. The first tube connector may further include a first tip part extending in a longitudinal direction of the first extension part from the first intermediate part.

The second tube connector may further include a second tip part extending in the longitudinal direction of the link pipes from the second connection part.

The connector module may further include a third tube connector having a different shape from the second tube connector. The third tube connector may include a third connection part connected to associated ones of the heads. The third connection part may have a larger length than the second connection part.

The third tube connector may further include a third extension part extending in the longitudinal direction of the link pipes from the third connection part. The third tube connector may further include an inclined part extending obliquely from the third extension part. The third tube connector may further include a third tip part extending in a longitudinal direction of the third extension part from the inclined part.

According to an aspect of another exemplary embodiment, there is provided a combined power generation system that includes a gas turbine configured to generate rotational force by burning fuel, a heat recovery steam generator configured to heat water using combustion gas discharged from the gas turbine and including a high-pressure section, a medium-pressure section, and a low-pressure section having different levels of pressure, and a steam turbine using steam heated by the heat recovery steam generator. The heat recovery steam generator includes a plurality of heat exchangers. Each of the heat exchangers includes a tube stack including a plurality of tubes, a plurality of heads connected to the tube stack and configured to accommodate heated steam, a connector module configured to connect the tubes and the heads and including a plurality of tube connectors, a manifold connected to the heads and configured to accommodate heated steam, and a plurality of link pipes configured to connect the heads and the manifold, and the connector module includes a first tube connector and a second tube connector having different shapes.

The heads may be spaced at different distances from the manifold.

The first tube connector may include a first connection part connected to associated ones of the heads, the second tube connector may include a second connection part connected to associated ones of the heads, and the first connection part may have a smaller length than the second connection part.

The first tube connector may further include a first extension part extending in a longitudinal direction of the link pipes from the first connection part, a first intermediate part extending in a longitudinal direction of the first connection part from the first extension part, and a first tip part extending in a longitudinal direction of the first extension part from the first intermediate part.

The connector module may further include a third tube connector having a different shape from the second tube connector, the third tube connector may include a third connection part connected to associated ones of the heads, and the third connection part may have a larger length than the second connection part.

The third tube connector may further include a third extension part extending in the longitudinal direction of the link pipes from the third connection part, an inclined part extending obliquely from the third extension part, and a third tip part extending in a longitudinal direction of the third extension part from the inclined part.

It is to be understood that both the foregoing general description and the following detailed description of exemplary embodiments are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed.

The above and other aspects will become more apparent from the following description of the exemplary embodiments with reference to the accompanying drawings, in which:.

Various modifications and different embodiments will be described below in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the disclosure. It should be understood, however, that the present disclosure is not intended to be limited to the specific embodiments, but the present disclosure includes all modifications, equivalents or replacements that fall within the spirit and scope of the disclosure as defined in the following claims.

The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the disclosure. In the disclosure, terms such as "comprises", "includes", or "have/has" should be construed as designating that there are such features, integers, steps, operations, components, parts, and/or combinations thereof, not to exclude the presence or possibility of adding of one or more of other features, integers, steps, operations, components, parts, and/or combinations thereof.

Exemplary embodiments will be described below in detail with reference to the accompanying drawings. It should be noted that like reference numerals refer to like parts throughout various drawings and exemplary embodiments. In certain embodiments, a detailed description of functions and configurations well known in the art may be omitted to avoid obscuring appreciation of the disclosure by those skilled in the art. For the same reason, some components may be exaggerated, omitted, or schematically illustrated in the accompanying drawings.

Hereinafter, a combined power generation system according to a first exemplary embodiment will be described.

<FIG> is a configuration diagram illustrating the combined power generation system according to the first exemplary embodiment. <FIG> is a configuration diagram illustrating a heat recovery steam generator according to the first exemplary embodiment.

Referring to <FIG>, the combined power generation system, which is designated by reference numeral <NUM>, according to the first exemplary embodiment may include a gas turbine <NUM>, a steam turbine <NUM>, a first generator G1, a second generator G2, and a heat recovery steam generator <NUM>.

In the gas turbine <NUM>, thermal energy may be released by combustion of fuel in an isobaric environment after atmospheric air is sucked and compressed to a high pressure, hot combustion gas may be expanded to be converted into kinetic energy, and exhaust gas with residual energy may then be discharged to the atmosphere.

The gas turbine <NUM> may include a compressor <NUM>, a combustor <NUM>, and a main turbine <NUM>. The compressor <NUM> of the gas turbine <NUM> may suck air from the outside and compress the air. The compressor <NUM> may supply the combustor <NUM> with the air compressed by compressor blades and may also supply cooling air to a hot region required for cooling in the gas turbine <NUM>.

Meanwhile, the combustor <NUM> may mix the compressed air, which is supplied from the outlet of the compressor <NUM>, with fuel for isobaric combustion to produce combustion gas with high energy.

The high-temperature and high-pressure combustion gas produced by the combustor <NUM> is supplied to the main turbine <NUM>. In the main turbine <NUM>, the combustion gas applies impingement or reaction force to a plurality of turbine blades radially disposed on the rotary shaft of the main turbine <NUM> while expanding adiabatically, so that the thermal energy of the combustion gas is converted into mechanical energy for rotating the rotary shaft. Some of the mechanical energy obtained from the main turbine <NUM> is supplied as energy required to compress the air in the compressor <NUM>, and the rest is utilized as effective energy, such as for driving the first generator G1 to generate electric power.

After the combustion gas flowing out of the main turbine <NUM> is cooled through the heat recovery steam generator <NUM>, it is purified and discharged to the outside. The heat recovery steam generator <NUM> not only cools the combustion gas, but also produces high-temperature and high-pressure steam using the heat of the combustion gas to deliver the steam to the steam turbine <NUM>.

The steam turbine <NUM> rotates the blades thereof using the steam produced by the heat recovery steam generator <NUM> and transfers rotational energy to the second generator G2. The steam turbine <NUM> supplies cooled steam back to the heat recovery steam generator <NUM>.

The first generator G1 may be connected to the gas turbine <NUM> and the second generator G2 may be connected to the steam turbine <NUM> so as to generate electric power. However, the present disclosure is not limited thereto, and a single generator may be connected to the gas turbine <NUM> and the steam turbine <NUM>.

The combined power generation system may be equipped with a condenser <NUM> for condensing steam, a condensate reservoir <NUM> for storing condensed water, and a condensate pump <NUM> for supplying the heat recovery steam generator <NUM> with the condensed water stored in the condensate reservoir <NUM>.

The steam flowing in the heat recovery steam generator <NUM> may have two or three levels of pressure, so that the water is pressurized to two or three or more levels of pressure. In the exemplary embodiment, the heat recovery steam generator <NUM> is exemplified as having three levels of pressure.

The heat recovery steam generator <NUM> may include a low-pressure section H1 having a relatively low pressure, a medium-pressure section H2 having a medium pressure, and a high-pressure section H3 having a relatively high pressure. The high-pressure section H3 may be disposed adjacent to an inlet for introduction of combustion gas therethrough and be heated by high-temperature combustion gas. The low-pressure section H1 may be disposed adjacent to an outlet for discharge of combustion gas therethrough and be heated by low-temperature combustion gas.

The heat recovery steam generator <NUM> includes a condensate preheater <NUM>, a low-pressure evaporator <NUM>, a medium-pressure economizer <NUM>, a medium-pressure evaporator <NUM>, a high-pressure economizer <NUM>, and a high-pressure evaporator <NUM>, which are installed therein. In addition, an additional superheater (not shown) may be installed upstream of each evaporator. The combustion gas flowing out of the heat recovery steam generator <NUM> may be discharged via a stack.

The low-pressure section H1 includes a condensate preheater <NUM>, a low-pressure evaporator <NUM>, and a low-pressure drum <NUM>. The condensed water stored in the condensate reservoir <NUM> is delivered to the condensate preheater <NUM> by the condensate pump <NUM>. The condensate preheater <NUM> heats the condensed water by exchanging heat with combustion gas. The water heated by the condensate preheater <NUM> is delivered to a deaerator <NUM> so that gas is removed from the condensed water.

Water is supplied from the deaerator <NUM> to the low-pressure drum <NUM>. The low-pressure evaporator <NUM> may be connected to the low-pressure drum <NUM>, so that the water stored in the low-pressure drum <NUM> is converted into steam by heating and the steam is then supplied to the superheater after steam-water separation in the low-pressure drum <NUM>.

The medium-pressure section H2 includes a medium-pressure economizer <NUM>, a medium-pressure evaporator <NUM>, and a medium-pressure drum <NUM>. The water in the deaerator <NUM> is supplied to the medium-pressure economizer <NUM> by a medium-pressure pump <NUM>. The medium-pressure economizer <NUM> heats the water by exchanging heat with combustion gas. The water heated in the medium-pressure economizer <NUM> is supplied to the low-pressure drum <NUM>. The medium-pressure evaporator <NUM> may be connected to the medium-pressure drum <NUM>, so that the water stored in the medium-pressure drum <NUM> is converted into steam by heating and the steam is then supplied to the superheater after steam-water separation in the medium-pressure drum <NUM>.

The high-pressure section H3 includes a high-pressure economizer <NUM>, a high-pressure evaporator <NUM>, a high-pressure drum <NUM>, and a high-pressure superheater <NUM>. The water in the deaerator <NUM> is supplied to the high-pressure economizer <NUM> by a high-pressure pump <NUM>. The high-pressure economizer <NUM> heats the water by exchanging heat with combustion gas. The water heated in the high-pressure economizer <NUM> is supplied to the high-pressure drum <NUM>. The high-pressure evaporator <NUM> may be connected to the high-pressure drum <NUM>, so that the water stored in the high-pressure drum <NUM> is converted into steam by heating and the steam is then supplied to the high-pressure superheater <NUM> after steam-water separation in the high-pressure drum <NUM>.

The steam stored in the low-pressure drum <NUM>, the medium-pressure drum <NUM>, and the high-pressure drum <NUM> may be supplied to low-pressure, medium-pressure, and high-pressure steam turbines, respectively.

<FIG> is a perspective view illustrating a heat exchanger according to the first exemplary embodiment. <FIG> is a top view illustrating the heat exchanger according to the first exemplary embodiment. <FIG> is a side view illustrating a first tube connector according to the first exemplary embodiment. <FIG> is a side view illustrating a second tube connector according to the first exemplary embodiment.

Referring to <FIG>, the heat exchanger, which is designated by reference numeral <NUM>, according to the present embodiment may be a once-through heat exchanger, and in particular, a vertical once-through heat exchanger applied to the heat recovery steam generator <NUM>. Alternatively, the heat exchanger <NUM> may be the high-pressure superheater <NUM> of the high-pressure section H3.

The heat exchanger <NUM> may include a tube stack <NUM>, a connector module <NUM>, a plurality of heads <NUM>, a plurality of link pipes <NUM>, and a manifold <NUM>. The tube stack <NUM> includes a plurality of tubes <NUM> and serves to overheat steam by exchanging heat with heated combustion gas. The tubes <NUM> may be connected in a straight line, and the steam flowing along the tube stack <NUM> may be heated by high-temperature combustion gas.

The connector module <NUM> connects the tubes <NUM> and the heads <NUM> and includes a plurality of tube connectors <NUM> and <NUM>. The tube connectors <NUM> and <NUM> may be composed of pipes each having a passage through which steam flows, and may each have a multiple curved structure. The tube connectors <NUM> and <NUM> may have a greater thickness than tubes <NUM>.

The heads <NUM> are connected to the connector module <NUM> and accommodate steam delivered from the connector module <NUM>. Each of the heads <NUM> is a pipe that extends parallel to the manifold <NUM> and has both longitudinal ends blocked.

The heads <NUM> are arranged in the longitudinal direction thereof and spaced at different distances from the manifold <NUM>. That is, one head <NUM> may be spaced apart from the manifold <NUM> by a first distance D11, and another head <NUM> may be spaced apart from the manifold <NUM> by a second distance D12 greater than the first distance D11. In particular, the heads <NUM> adjacent to each other in the longitudinal direction of the manifold <NUM> are spaced at different distances from the manifold <NUM>.

The link pipes <NUM> may connect the heads <NUM> and the manifold <NUM>. In addition, the manifold <NUM> and any one of the heads <NUM> may be connected by two link pipes <NUM>. The link pipes <NUM> may each have a thickness greater than that of the connector module <NUM>.

The manifold <NUM> may be a long pipe, and the heads are connected to the manifold through the link pipes. The manifold <NUM> may have a plurality of connection pipes 151a formed for introduction or discharge of steam.

Meanwhile, the connector module <NUM> may include a first tube connector <NUM> and a second tube connector <NUM> having different shapes. One head <NUM> may be connected to both the first tube connector <NUM> and the second tube connector <NUM>, and some other heads <NUM> may be connected to only the first tube connector <NUM>. The other heads <NUM> may also be connected to only the second tube connector <NUM>.

The first tube connector <NUM> may include a first connection part <NUM> connected to associated ones of the heads <NUM>, a first extension part <NUM> extending in the longitudinal direction of the link pipes <NUM> from the first connection part <NUM>, a first intermediate part <NUM> extending in the longitudinal direction of the first connection part <NUM> from the first extension part <NUM>, and a first tip part <NUM> extending in the longitudinal direction of the first extension part <NUM> from the first intermediate part <NUM>. The first tip part <NUM> is connected to associated ones of the tubes <NUM>.

Meanwhile, the first tube connector <NUM> may further include a bent part BD1 connected to the side ends of the associated heads <NUM>, and the first connection part <NUM> may be connected to the associated heads <NUM> via the bent part BD1.

The second tube connector <NUM> may include a second connection part <NUM> connected to associated ones of the heads <NUM>, and a second tip part <NUM> extending in the longitudinal direction of the link pipes <NUM> from the second connection part <NUM>. Meanwhile, the second tube connector <NUM> may further include a bent part BD1 connected to the side ends of the associated heads <NUM>, and the second connection part <NUM> may be connected to the associated heads <NUM> via the bent part BD1.

Here, the first connection part <NUM> and the second connection part <NUM> may be formed in parallel, and the length L11 of the first connection part <NUM> may be smaller than the length L12 of the second connection part <NUM>.

As in the first exemplary embodiment, if the adjacent heads <NUM> are spaced at different distances from the manifold <NUM>, it is possible to absorb an amount of deformation when the tubes <NUM>, the heads <NUM>, and the manifold <NUM> are deformed by steam. In addition, if the first and second tube connectors <NUM> and <NUM> have different shapes and the first connection part <NUM> has a smaller length than the second connection part <NUM>, it is possible to minimize deformation of the arrangement of the tubes <NUM> caused by thermal deformation or damage to the piping caused by thermal stress.

Hereinafter, a heat exchanger according to a second exemplary embodiment will be described.

<FIG> is a perspective view illustrating the heat exchanger according to the second exemplary embodiment. <FIG> is a side view illustrating a third tube connector according to the second exemplary embodiment.

Referring to <FIG>, the heat exchanger, which is designated by reference numeral <NUM>, according to the second exemplary embodiment may include a tube stack <NUM>, a connector module <NUM>, a plurality of heads <NUM>, a plurality of link pipes <NUM>, and a manifold <NUM>.

Since the heat exchanger <NUM> according to the second exemplary embodiment has the same structure as the heat exchanger according to the first exemplary embodiment, with the sole exception of the connector module <NUM>, a redundant description thereof will be omitted.

The connector module <NUM> connects the tubes <NUM> and the heads <NUM> and includes a plurality of tube connectors <NUM> and <NUM>. In addition, the connector module <NUM> may include a second tube connector <NUM> and a third tube connector <NUM> having different shapes. The second tube connector <NUM> and the third tube connector <NUM> may be connected to different heads.

The third tube connector <NUM> may include a third connection part <NUM> connected to associated ones of the heads <NUM>, a third extension part <NUM> extending in the longitudinal direction of the link pipes from the third connection part <NUM>, an inclined part <NUM> extending obliquely from the third extension part <NUM>, and a third tip part <NUM> extending in the longitudinal direction of the third extension part <NUM> from the inclined part <NUM>. The third tip part <NUM> is connected to associated ones of the tubes <NUM>.

Meanwhile, the third tube connector <NUM> may further include a bent part BD1 connected to the side ends of the associated heads <NUM>, and the third connection part <NUM> may be connected to the associated heads via the bent part BD1.

Here, the third connection part <NUM> and the second connection part <NUM> may be formed in parallel, and the length L13 of the third connection part <NUM> may be larger than the length L12 of the second connection part <NUM>.

As in the second exemplary embodiment, if the second and third tube connectors <NUM> and <NUM> have different shapes and the second connection part <NUM> has a smaller length than the third connection part <NUM>, it is possible to reliably prevent the tubes <NUM> from being broken due to thermal deformation.

Hereinafter, a heat exchanger according to a third exemplary embodiment will be described.

<FIG> is a perspective view illustrating the heat exchanger according to the third exemplary embodiment.

Referring to <FIG>, the heat exchanger, which is designated by reference numeral <NUM>, according to the third exemplary embodiment may include a tube stack <NUM>, a connector module <NUM>, a plurality of heads <NUM>, a plurality of link pipes <NUM>, and a manifold <NUM>.

Since the heat exchanger <NUM> according to the third exemplary embodiment has the same structure as the heat exchanger according to the first exemplary embodiment, with the sole exception of the connector module <NUM>, a redundant description thereof will be omitted.

The connector module <NUM> connects the tubes <NUM> and the heads <NUM> and includes a plurality of tube connectors <NUM>, <NUM>, and <NUM>. In addition, the connector module <NUM> may include a first tube connector <NUM>, a second tube connector <NUM>, and a third tube connector <NUM> having different shapes. The first tube connector <NUM> and the second tube connector <NUM> may be connected to the same head or different heads <NUM>. Meanwhile, the third tube connector <NUM> may be connected to heads <NUM> different from those connected to the first and second tube connectors <NUM> and <NUM>.

The first and second tube connectors <NUM> and <NUM> according to the third exemplary embodiment may have the same structure as the first and second tube connectors <NUM> and <NUM> of the above-mentioned first exemplary embodiment. The third tube connector <NUM> according to the third exemplary embodiment may have the same structure as the third tube connector <NUM> of the second exemplary embodiment.

As in the third exemplary embodiment, if the first, second, and third tube connectors <NUM>, <NUM>, and <NUM> have different shapes, the first connection part <NUM> has a smaller length than the second connection part <NUM>, and the second connection part <NUM> has a smaller length than the third connection part <NUM>, it is possible to reliably prevent the tubes from being broken due to thermal deformation.

Hereinafter, a heat exchanger according to a fourth exemplary embodiment will be described.

<FIG> is a perspective view illustrating the heat exchanger according to the fourth exemplary embodiment.

Referring to <FIG>, the heat exchanger, which is designated by reference numeral <NUM>, according to the fourth exemplary embodiment may include a tube stack <NUM>, a connector module, a plurality of heads <NUM>, a plurality of link pipes <NUM>, and a manifold <NUM>. The manifold <NUM> may be a long pipe, and may have a plurality of connection pipes 181a formed for introduction or discharge of steam.

Since the heat exchanger <NUM> according to the fourth exemplary embodiment has the same structure as the heat exchanger according to the first exemplary embodiment, with the sole exception of the link pipes <NUM>, a redundant description thereof will be omitted.

The link pipes <NUM> may connect the heads <NUM> and the manifold <NUM>. In addition, the manifold <NUM> and any one of the heads <NUM> may be connected by two link pipes <NUM>. The connector module may include a first tube connector <NUM> and a second tube connector <NUM>, but the present disclosure is not limited thereto.

The link pipes coupled to different heads are formed to have different lengths, and the link pipes having different lengths are arranged obliquely to each other. Some of the link pipes may be inclined upward, while some of the link pipes may be inclined downward.

As in the fourth exemplary embodiment, if the link pipes have different lengths and the link pipes <NUM> are inclined to each other, it is possible to reliably prevent the tubes from being broken due to thermal deformation.

As is apparent from the above description, the once-through heat exchanger according to the exemplary embodiments can prevent breakage and stress concentration due to thermal deformation since the heads are spaced at different distances from the manifold and the heads and the manifold are connected via the link pipes.

In addition, since the tube connectors constituting the connector module have different shapes, it is possible to minimize deformation of the arrangement of the tubes caused by thermal deformation or damage to the piping caused by thermal stress.

Claim 1:
A once-through heat exchanger (<NUM>, <NUM>) comprising:
a tube stack (<NUM>) comprising a plurality of tubes (<NUM>);
a plurality of heads (<NUM>, <NUM>) connected to the tube stack (<NUM>) and configured to accommodate heated steam;
a connector module (<NUM>, <NUM>, <NUM>) configured to connect the tubes (<NUM>) and the heads (<NUM>, <NUM>) and comprising a plurality of tube connectors (<NUM>, <NUM>, <NUM>);
a manifold (<NUM>, <NUM>) connected to the heads (<NUM>, <NUM>) and configured to accommodate heated steam; and
a plurality of link pipes (<NUM>, <NUM>) configured to connect the heads (<NUM>, <NUM>) and the manifold (<NUM>, <NUM>),
wherein the connector module (<NUM>, <NUM>, <NUM>) comprises a first tube connector (<NUM>) and a second tube connector (<NUM>) having different shapes;
characterized in that:
each of the heads (<NUM>) is a pipe that extends parallel to the manifold (<NUM>) and has both longitudinal ends blocked, and
in that the heads (<NUM>, <NUM>) are spaced at different distances from the manifold (<NUM>, <NUM>).