JP2012520985A - High efficiency steam generator and method - Google Patents

Abstract

The present invention relates to the generation of steam from the working medium (A) of the boiler, preferably configured as a waste heat boiler, a carina boiler or an ORC boiler, and utilizes a heat generator pre-connected to the boiler. Since the boiler uses a hot heat transfer medium heated in a heat generator before being fed to the boiler according to the present invention to evaporate the working medium, high steam generation efficiency can be achieved. As a heat source for the heat generator, for example, residual heat or waste heat of industrial equipment, or geothermal equipment using geothermal heat is used.
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Description

  The present invention relates to steam generation of a boiler using a heat generator connected in front of the boiler.

  For example, in many industrial processes and papermaking at steel mills and cement mills, it is possible to use a heat source at an intermediate temperature level in the form of waste heat at the end of the process. This waste heat can be used to operate the boiler and thereby ultimately generate an electric current. Conveniently, the thermal energy stored in the waste heat that would otherwise be lost is available, thereby increasing the actual efficiency of the overall industrial process.

  As is well known in boilers, the working medium is evaporated and this is then fed, for example, to a turbine coupled to a generator. In order to evaporate the working medium, a heated heat transfer medium is supplied to the boiler and the heat stored in the heat transfer medium is transferred to the working medium, which results in evaporation of the working medium. When using waste heat of an industrial process, this heat transfer medium is heated using waste heat. In this case, an intermediate temperature level of the heat transfer medium typically in the range of about 60 ° C. to 200 ° C. is only reachable. Therefore, the efficiency when steam is generated based on the waste heat of the industrial process is relatively poor.

  Instead, geothermal equipment can also be used as a heat source. As is well known in geothermal facilities, the heat transfer medium is poured into the deep boring to heat the heat transfer medium by geothermal heat. Again, the heat transfer medium removed from the deep bore is only at an intermediate temperature level. The heat energy stored in the heat transfer medium can be used for steam generation as described above, but in this case as well, the steam generation efficiency is relatively poor.

  An object of the present invention is to improve the efficiency of steam generation using the heat of a heat transfer medium at an intermediate temperature level.

  This problem is solved by the invention described in the independent claims. Advantageous embodiments result from the dependent claims.

  The basic idea of the problem-solving means according to the present invention is to use a heat generator, also called “Waermetransformator” in the literature, to increase the temperature of the heat transfer medium that causes evaporation of the working medium. There is to do. Heat generators are commonly used to generate high temperature levels of heat by supplying intermediate temperature levels of heat and carrying away low temperature levels of heat.

  The heat generator is supplied with a primary heat transfer medium at an intermediate temperature level. For example, the primary heat transfer medium can be brought to an intermediate temperature by using a heat source such as the industrial facility waste heat pipe or the geothermal facility described above. A secondary medium having a temperature higher than that of the primary heat transfer medium can be taken out from the heat generator or heat converter. The mode of operation of the heat generator is known, for example, from German Offenlegungsschrift 352 211 195 or German Pat. No. 19816022 and is therefore not further described here.

  With the heat generator, the heat accumulated in the primary heat transfer medium can be used for heating the secondary heat transfer medium. In doing so, it is now possible to heat or evaporate the working medium with relatively high efficiency in a boiler using a relatively high temperature secondary heat transfer medium.

  In the steam generation method according to the present invention, heat energy is transferred in the boiler heat exchanger in order to evaporate the working medium of the boiler, particularly configured as a waste heat boiler, a carina boiler or an ORC (organic Rankine cycle) boiler. Transmitted from the medium to the working medium. By increasing the temperature of the heat transfer medium in the heat generator according to the present invention before supplying the heat transfer medium to the heat exchanger, high steam generation efficiency can be ensured.

  In an industrial facility where the heat generator is supplied with thermal energy by another heat transfer medium and generates residual heat or waste heat, the residual heat or The use of waste heat increases the temperature of this other heat transfer medium. This achieves that residual heat or waste heat that would otherwise be lost in industrial equipment can be used for steam generation.

  In an alternative embodiment, the heat generator is also supplied with thermal energy by another heat transfer medium. The temperature of this other heat transfer medium is increased using geothermal heat in the geothermal facility, before this other heat transfer medium is supplied to the heat generator, so that geothermal heat is effectively used for steam generation. Can be used.

  The temperature of the other heat transfer medium supplied to the heat generator is lower in both embodiments than the temperature of the heat transfer medium supplied to the boiler heat exchanger.

  Particularly in the apparatus according to the invention for evaporating the working medium in a heat exchanger of a boiler configured as a waste heat boiler, a carina boiler or an ORC boiler, the heat energy is transferred in the heat exchanger for evaporating the working medium. It can be transmitted from the medium to the working medium. Furthermore, the apparatus has a heat generator for increasing the temperature of the heat transfer medium.

  The heat generator can be supplied with thermal energy with the aid of another heat transfer medium. Before the other heat transfer medium is supplied to the heat generator, the temperature of the other heat transfer medium is increased by utilizing the residual heat or waste heat in an industrial facility that generates the residual heat or waste heat. Good. This allows residual heat or waste heat from industrial equipment that would otherwise be lost to be utilized for steam generation.

  In an alternative embodiment, the heat generator can be supplied with thermal energy by another heat transfer medium. Before this other heat transfer medium is supplied to the heat generator, the temperature of this other heat transfer medium can be increased using geothermal heat in the geothermal installation, so geothermal heat is effective for steam generation. Can be used.

  Other advantages, features and details of the invention will become apparent from the embodiments described below on the basis of the drawings.

FIG. 1 shows the use of waste heat for steam generation according to the prior art. FIG. 2 shows a first embodiment of a heat generator for utilizing the waste heat of industrial equipment. FIG. 3 shows a second embodiment of the heat generator for utilizing the heat generated in the geothermal facility.

  In these figures, the same or corresponding ranges, components, component groups or method steps are denoted by the same reference numerals. The direction of flow in the piping is indicated by arrows.

  FIG. 1 shows the known possibility of using the waste heat of an industrial facility 100, for example a steel mill, to evaporate the working medium A of the boiler 200. A heat exchanger 120 that is flowed by the heat transfer medium W is installed in the waste heat pipe 110 that is simply shown in the steel mill 100. The temperature of the heat transfer medium W is increased from the temperature T1 (W) to the temperature T2 (W) in the heat exchanger 120.

  The heated heat transfer medium W is carried by the pump 140 and reaches the heat exchanger 220 of the boiler 200 through the pipe 130. Furthermore, the heat exchanger 220 is flowed through by the working medium A to be evaporated. In the heat exchanger 220, heat is transferred from the heat transfer medium W to the working medium A. At this time, the working medium A is heated and evaporated, whereas the temperature of the heat transfer medium W is correspondingly lowered. To do. The cooled heat transfer medium W is subsequently refluxed through the pipe 150 to the heat exchanger 120 in the waste heat pipe 110 of the steel mill 100 where it is heated again.

  The working medium A evaporated in the boiler heat exchanger 220 is supplied to the turbine 240 via the pipe 230 to drive it. Since the turbine 240 is finally connected to the generator 250 to generate a current, the current can be generated by utilizing the waste heat of the steel mill 100 as is known. The working medium A expanded in the turbine 240 is typically led to the cooler 270 via the pipe 260 following the turbine 240 and then transported again to the heat exchanger 220 with the help of the pump 280.

  FIG. 2 shows a first application example of the device according to the invention. Also in this case, the heat exchanger 120 is present in the waste heat pipe 110 of the industrial equipment 100, and in this heat exchanger 120, the waste heat of the industrial equipment 100 converts the primary heat transfer medium W1 to the temperature T1 ( Used to heat from W1) to a higher temperature T2 (W1). The heated primary heat transfer medium W1 reaches the inlet 301 of the heat generator 300 through the pipe 130 with the help of the pump 140.

  As mentioned at the outset, with the help of the heat generator 300, the heat stored in the waste heat stream of the industrial facility 100 at a relatively low temperature level T1 of about 60 ° C. to 80 ° C. can be used for the following: it can. That is, the temperature of the secondary heat transfer medium W2 used in the subsequent process of the heat generator 300, for example, steam generation is increased, and the temperature of the working medium A of the subsequent process is increased on the secondary heat transfer medium W2 side. In particular, it can be used for evaporating the working medium A.

  The primary heat transfer medium W <b> 1 passes through the heat generator 300, is cooled by a process performed in the heat generator 300, and can be finally taken out at the outlet 302. The primary heat transfer medium W1 returns from the outlet 302 via the pipe 150 to the heat exchanger 120 in the waste heat pipe 110 of the industrial facility 100, where it is heated again.

  The secondary heat transfer medium W2 is introduced into the heat generator 300 through the inlet 303. In this heat generator, the secondary heat transfer medium W2 is finally heated from the temperature T1 (W2) to the temperature T2 (W2) by using the heat of the primary heat transfer medium W1. The secondary heat transfer medium W <b> 2 thus heated is now taken out at the outlet 304 of the heat generator 300 and supplied to the heat exchanger 220 of the boiler 200 through the pipe 210 with the help of the pump 310. This causes the working medium A of the boiler 200 to evaporate in the heat exchanger 220 as described in connection with FIG. 1, and as a result, current can be generated by the turbine 240 and the generator 250. At that time, the secondary heat transfer medium W2 is cooled, and subsequently introduced again into the inlet 303 of the heat generator 300 via the pipe 290, where it is heated again.

  Thanks to the use of the heat generator 300, the efficiency of steam generation or current generation is higher than in the case of the known equipment in the prior art described in connection with FIG. This heat generator is effectively connected between the waste heat piping of the industrial facility and the boiler, and acts so that the heat transfer medium supplied to the boiler has a higher temperature.

  For completeness, FIG. 2 still shows an inlet 305 and an outlet 306 that allow the heat generator 300 to supply and discharge another medium. As mentioned in the introduction, heat generators generally generate heat at high temperature levels by supplying heat at intermediate temperature levels and exhausting heat at low temperature levels. Used. The media supplied through inlet 305 and available at outlet 306 is used to exhaust heat at a low temperature level. With the help of the primary heat transfer medium W1, heat at an intermediate temperature level is supplied, and the secondary heat transfer medium W2 derives heat at a high temperature level and transports this to the heat exchanger 220 of the boiler 200. .

  FIG. 3 shows a second application example of the device according to the invention. The primary heat transfer medium W1 has heretofore been provided with a temperature T2 (W1) that has been increased with the aid of waste heat from the industrial equipment, but here it is heated in the geothermal equipment 400. As is well known, geothermal facilities use the heat stored in the crust. Since the heat exchanger 410 is disposed at a predetermined depth and is flowed by the primary heat transfer medium W1, in order to increase the temperature T1 (W1) of the primary heat transfer medium W1 to the value T2 (W1) The dominant elevated temperature can be used there. The primary heat transfer medium W1 thus heated is conveyed to the inlet 301 of the heat generator 300 via the pipe 430 with the help of the pump 420 according to the present invention. As described above, the heat generator 300 is used to heat the secondary heat transfer medium W2 from the temperature T1 (W2) to the temperature T2 (W2) based on the heat accumulated in the primary heat transfer medium W1. The The heated heat transfer medium W2 is then used for steam generation and current generation in the boiler 200 in a manner similar to the method described in connection with FIG.

  In these figures, the present invention is specifically described with application examples in industrial and geothermal facilities. The industrial equipment may be basically equipment in which residual heat or waste heat is incidentally generated, that is, for example, a steel mill, a cement factory, a paper mill and the like. It is also conceivable to use the waste heat of the power plant for the above-mentioned purposes. Waste heat generated at the power plant, for example waste heat generated in the exhaust gas after combustion of the fuel and / or behind the turbine, contains significant stored energy, particularly in the form of residual heat. This residual heat can be used to heat the above-described primary heat transfer medium supplied to the heat generator according to the present invention. This heat generator is used to bring higher temperatures to the secondary heat transfer medium. In doing so, the secondary heat transfer medium can preheat, for example, the combustion air required for combustion in the power plant to produce efficient combustion. This secondary heat transfer medium may be used to generate a current for power plant equipment, for example, a pump, in the boiler as described above.

  In general terms, all these facilities suitable for applying the present invention as described above, namely industrial facilities that generate residual heat or waste heat, including power plants, geothermal facilities, etc., are “heat sources”. It is summarized in the concept. That is, this is generally a facility that can freely use thermal energy that allows the primary heat transfer medium to be heated from a lower temperature T1 (W1) to a higher temperature T2 (W1).

  The boiler 200 shown in these drawings may be, for example, a waste heat boiler (AHDE or HRSG, “exhaust heat recovery boiler”), a carina boiler, or an ORC boiler. Common to all these special boilers is that the working medium to be evaporated has a lower boiling point than water. The so-called “carina process” is a method of steam generation at low temperature levels, where the working medium to be evaporated is not water, but an ammonia / water mixture, which already evaporates at low temperatures. Similarly, the so-called “ORC process” is known, in which an organic liquid having a low evaporation temperature is used as the working medium to be evaporated.

  However, the use of a boiler that operates with water as the working medium A is basically not excluded due to the increased temperature T2 (W2) of the secondary heat transfer medium.

  Both the ORC process and the carina process are suitable for generating steam by utilizing the heat of the heat transfer medium at low or intermediate temperature levels. However, the efficiency at the time of steam generation is very strongly dependent on the temperature of the heat source or heat transfer medium. For example, when the temperature of the heat transfer medium is increased from 60 ° C. to 120 ° C., the Carnot efficiency is improved three times. Raising the temperature to 200 ° C. increases the efficiency to a value about 5 times. Thus, the use of a heat generator that heats the heat transfer medium in front of the boiler according to the present invention provides an advantageous result in efficiency.

100 Industrial Equipment 110 Waste Heat Piping 120 Heat Exchanger 130 Piping 140 Pump 150 Piping 200 Boiler 210 Piping 220 Heat Exchanger 230 Piping 240 Turbine 250 Generator 260 Piping 270 Cooler 280 Pump 290 Piping 300 Heat Generator 301 Inlet 302 Outlet 303 Inlet 304 Outlet 305 Inlet 306 Outlet 310 Pump 400 Geothermal facility 410 Heat exchanger 420 Pump 430 Pipe A Working medium W1 Primary heat transfer medium W2 Secondary heat transfer medium

The heat generator is supplied with a primary heat transfer medium at an intermediate temperature level. For example, the primary heat transfer medium can be brought to an intermediate temperature by using a heat source such as the industrial facility waste heat pipe or the geothermal facility described above. A secondary medium having a temperature higher than that of the primary heat transfer medium can be taken out from the heat generator or heat converter. Heat generator is a so-called "absorption heat pump", the operation mode of its is, for example, known from German Patent Application Publication No. 3521195 or German Patent No. 19816022, here therefore it No further explanation is given above.

Claims (7)

A method for evaporating a working medium (A) of a boiler (200), in particular a waste heat boiler, a carina boiler or an ORC boiler, evaporating the working medium (A) in a heat exchanger (220) of the boiler (200) In order that the heat energy is transferred from the heat transfer medium (W2) to the working medium (A),
The method characterized in that the temperature (T (W2)) of the heat transfer medium (W2) is raised in the heat generator (300) before the heat transfer medium (W2) is supplied to the heat exchanger (220). .   Heat energy is supplied to the heat generator (300) by another heat transfer medium (W1), and residual heat or waste is discharged before the other heat transfer medium (W1) is supplied to the heat generator (300). The temperature (T (W1)) of the other heat transfer medium (W1) is increased by utilizing residual heat or waste heat in the industrial facility (100) that generates heat. the method of.   Heat energy is supplied to the heat generator (300) by another heat transfer medium (W1), and before this other heat transfer medium (W1) is supplied to the heat generator (300), the geothermal equipment (400 The method according to claim 1, characterized in that the temperature (T (W1)) of the other heat transfer medium (W1) is increased using geothermal heat.   The temperature (T2 (W1)) of another heat transfer medium (W1) supplied to the heat generator (300) is the heat transfer medium (W2) supplied to the heat exchanger (220) of the boiler (200). 4. The method according to claim 2, wherein the temperature is lower than the temperature T2 (W2). A device for evaporating the working medium (A) in a heat exchanger (220) of a boiler (200), in particular a waste heat boiler, a carina boiler or an ORC boiler, for heat exchange for evaporating the working medium (A) In the apparatus in which heat energy can be transferred from the heat transfer medium (W2) to the working medium (A) in the vessel (220),
The apparatus has a heat generator (300) for increasing the temperature (T (W2)) of the heat transfer medium (W2).   Heat energy can be supplied to the heat generator (300) by another heat transfer medium (W1), and before the other heat transfer medium (W1) is supplied to the heat generator (300), The temperature (T (W1)) of another heat transfer medium (W1) can be increased by utilizing the residual heat or waste heat in the industrial facility (100) that generates the residual heat or waste heat. Item 6. The device according to Item 5.   Heat energy can be supplied to the heat generator (300) by another heat transfer medium (W1), and before the other heat transfer medium (W1) is supplied to the heat generator (300), The device according to claim 5, characterized in that the temperature (T (W1)) of the other heat transfer medium (W1) can be increased using geothermal heat in the geothermal installation (400).

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