CN206530370U - Using the Brayton Cycle system of supercritical carbon dioxide - Google Patents

Abstract

The utility model discloses a kind of Brayton Cycle system for the use supercritical carbon dioxide for belonging to power station energy-saving field, the circulatory system is main to be made up of boiler hearth heating surface, heated surface at the end of boiler, air preheater, boiler back end ductwork, cycle fluid bypass duct, high temperature regenerator, middle temperature regenerator, cryogenic regenerator, working medium turbine, high temperature compressor, a cold pressing mechanism of qi and cooler.By the way that boiler hearth heating surface is rearranged, the bypass of high temperature regenerator is set, so as to match newly-designed supercritical carbon dioxide cycle heat exchange demand；Improve cycle efficieny；Improve low-temperature flue gas utility；Improve air preheater caloric receptivity distribution, the design heat exchange amount for being optimized to correspondence air preheater in being circulated substantially with coal-fired steam is identical；Using a cold compression technology, cycle efficieny is improved, the heat exchange for optimizing cooler is interval, is allowed to match with water-cooling system.In addition the system architecture is simple, and operational efficiency is high, there is preferable application prospect in engineering.

Description

Brayton cycle system using supercritical carbon dioxide

technical field

The utility model belongs to the field of power station energy saving, in particular to a Brayton cycle system using supercritical carbon dioxide.

Background technique

The supercritical carbon dioxide (S-CO ₂ ) Brayton cycle is a cycle mode in which carbon dioxide in a supercritical state (critical pressure 7.38MPa, critical temperature 31.05°C) is used as the working medium, and the principle of Brayton cycle is used to realize energy conversion.

The use of supercritical fluid as the circulating working medium is to take advantage of the advantages of high density and low viscosity of the fluid near the supercritical point to reduce the power consumption of the compressor and improve the cycle efficiency. Moreover, supercritical carbon dioxide has the characteristics of non-toxicity, abundant reserves, low cost, stable performance, high density, relatively low critical temperature and pressure, and is considered one of the best circulating working fluids. Compared with the steam power cycle currently used on a large scale, the supercritical carbon dioxide Brayton cycle has higher energy conversion efficiency at high temperature (generally higher than 400°C), and its system is compact and the equipment volume is small (the volume of the turbine system and cooling equipment is only It is equivalent to one tenth of the corresponding equipment volume of the steam system), which is easy to be modularized and has good potential economy; compared with the conventional gas Brayton cycle, its compression process parameters are located near the critical point of the working medium, making the compression work The consumption is significantly reduced and the cycle efficiency is significantly improved.

Supercritical carbon dioxide was proposed as a working fluid in the power cycle in the 1960s, but it was not widely used due to technical limitations at that time. In recent years, with the improvement of technology level, the application of supercritical carbon dioxide in nuclear reactors has been widely concerned and researched by scholars and research institutions at home and abroad, and its combination with tower solar heat absorbers has also been widely carried out. Coal-fired boilers are the main power generation methods, but the application of supercritical carbon dioxide in them develops relatively slowly.

Energy conservation and emission reduction of large thermal power units is an important energy strategy in China. In order to adapt to the rapid development of the electricity market and the huge pressure of energy conservation and emission reduction, we urgently need to find new ways to improve the efficiency of power plants, which has become a topic that every power plant pays more and more attention to.

Utility model content

The purpose of this utility model is to address the deficiencies in the prior art and propose a Brayton cycle system using supercritical carbon dioxide, which is characterized in that: the heating surface of the boiler furnace is redesigned, and the boiler tail is arranged sequentially in the boiler tail flue to receive heat Surface 4 and air preheater 3; the outlet of boiler furnace heating surface 1 is connected to the inlet of working medium turbine 5, the outlet of working medium turbine 5 is connected to high temperature regenerator 6, and the high temperature regenerator 6 is connected to medium temperature regenerator 7 , the medium-temperature regenerator 7 is connected to the low-temperature regenerator 8, the outlet of the low-temperature regenerator 8 is connected to the high-temperature compressor 9 and the first condenser 12, and the outlet of the high-temperature compressor 9 is connected to the medium-temperature regenerator 7 and the low-temperature regenerator The regenerators 8 are connected by a pipeline 15, the high temperature regenerator 6 and the medium temperature regenerator 7 are connected by a pipeline 14, and the pipeline 14 between the high temperature regenerator 6 and the medium temperature regenerator 7 is further Connect the high temperature regenerator bypass 16, the high temperature regenerator bypass 16 flows into the boiler furnace heating surface 1 through the boiler tail heating surface 4 and the high temperature regenerator 6 outlet together; the first condenser 12 outlet and the first room The cold compressor 10 is connected, the outlet of the first cold compressor 10 is connected with the second condenser 13, the outlet of the second condenser 13 is connected with the second cold compressor 11, and the outlet of the second cold compressor 11 is connected with the low temperature Regenerator 8 is connected.

The high-temperature regenerator bypass 16 is set between the high-temperature regenerator 6 and the medium-temperature regenerator 7, the inlet temperature is 320°C, and the outlet temperature is 470°C, thereby effectively utilizing the low-temperature smoke at 350°C-500°C Gas heat, improve the system cycle efficiency.

The intercooling compression of the two intercooling compressors improves the circulation efficiency of the circulation system and maintains the heat exchange temperature of the cooler between 30° C. and 80° C., which is well matched with the temperature of the water cooling system.

The flue at the tail of the boiler is arranged in sequence with the heating surface 4 at the tail of the boiler and the air preheater 3, so that the heat exchange range of the air preheater in this cycle is 100°C-350°C, and the heat transfer is basically the same as that in the coal-fired steam cycle. The design heat transfer capacity of the corresponding air preheater is the same, thus optimizing the heat transfer characteristics of the air preheater.

The beneficial effects of the utility model are:

1. The system has a high-temperature regenerator bypass outside the high-temperature regenerator. Part of the working fluid from the medium-temperature regenerator directly enters the tail flue of the boiler to absorb the heat of low-temperature flue gas, and finally connects with the outlet of the high-temperature regenerator. The working fluids are mixed and flow into the heating surface of the boiler furnace together. This bypass optimizes the system structure, improves the absorption performance of the low-temperature flue gas of the boiler, absorbs the heat of the flue gas between 350°C and 500°C, and improves the cycle efficiency of the system.

2. Rearrange the heating surface of the boiler furnace to match the heat transfer characteristics of the newly designed supercritical carbon dioxide cycle, making the heat transfer efficient and compact, and ensuring the stable operation of the boiler.

3. The system adopts intercooling compression technology, which not only improves the cycle efficiency of the system, but also optimizes the heat transfer temperature range of the condenser to match it with the water cooling system.

4. The system has no reheating cycle, which simplifies the control system and furnace layout, has room for further efficiency improvement, and has a good application prospect in engineering. If the control system is advanced enough, the effect of the system can be further improved by adding a reheat cycle.

5. The system layout scheme has wide applicability, and it can be decided whether to use intercooling compression according to the parameters of the unit and the cooling method.

Description of drawings

Figure 1 is a schematic diagram of a supercritical carbon dioxide Brayton cycle system.

detailed description

The utility model proposes a Brayton cycle system using supercritical carbon dioxide. The following will be described in conjunction with the accompanying drawings and examples.

As shown in Figure 1, it is a schematic diagram of the supercritical carbon dioxide Brayton cycle system. The utility model redesigns the boiler furnace heating surface, and arranges the boiler tail heating surface 4 and the air preheater 3 in sequence in the boiler tail flue; the boiler furnace heating surface The outlet of 1 is connected to the inlet of working fluid turbine 5, the outlet of working fluid turbine 5 is connected to high temperature regenerator 6, the high temperature regenerator 6 is connected to medium temperature regenerator 7, and the medium temperature regenerator 7 is connected to low temperature regenerator 8 , the outlet of the low-temperature regenerator 8 is connected to the high-temperature compressor 9 and the first condenser 12 respectively, and the outlet of the high-temperature compressor 9 is connected to the medium-temperature regenerator 7 and the low-temperature regenerator 8 through a pipeline 15. The heater 6 and the medium temperature regenerator 7 are connected through a pipeline 14, and the high temperature regenerator bypass 16 is connected to the pipeline 14 between the high temperature regenerator 6 and the medium temperature regenerator 7, and the high temperature regenerator The bypass 16 flows into the boiler furnace heating surface 1 through the boiler tail heating surface 4 and the outlet of the high-temperature regenerator 6; thus, the boiler furnace heating surface matches the newly designed supercritical carbon dioxide cycle, optimizes the layout of the heating surface, and ensures efficient operation of the boiler.

The outlet of the first condenser 12 of the circulation system is connected with the first intercooler compressor 10, the outlet of the first intercooler compressor 10 is connected with the second condenser 13, and the outlet of the second condenser 13 is connected with the second intercooler. The cold compressor 11 is connected, and the outlet of the second inter-cooled compressor 11 is connected with the low-temperature regenerator 8, that is, the two inter-cooled compressors adopt the inter-cooled compression technology, which improves the circulation efficiency of the circulation system and makes the heat exchange temperature of the cooler It is maintained between 30°C and 80°C, which matches well with the temperature of the water cooling system.

The high-temperature regenerator bypass 16 is set between the high-temperature regenerator 6 and the medium-temperature regenerator 7, the inlet temperature is 320°C, and the outlet temperature is 470°C, thereby effectively utilizing the low-temperature smoke at 350°C-500°C Gas heat, improve the system cycle efficiency.

The flue at the tail of the boiler is arranged in sequence with the heating surface 4 at the tail of the boiler and the air preheater 3, so that the heat exchange range of the air preheater in this cycle is 100°C-350°C, and the heat transfer is basically the same as that in the coal-fired steam cycle. The design heat transfer capacity of the corresponding air preheater is the same, thus optimizing the heat transfer characteristics of the air preheater.

The utility model proposes for the first time that a high-temperature regenerator bypass is set in the supercritical carbon dioxide Brayton cycle system, and a part of the medium-temperature regenerator outlet directly enters the subsequent high-temperature regenerator; another part of the medium-temperature regenerator outlet works The mass first enters the heat exchange surface at the end of the furnace to absorb heat, thereby absorbing the waste heat at the end of the furnace, reducing unnecessary heat absorption during the design of the air preheater, and improving the cycle efficiency of the system. Finally, the temperature distribution of the flue gas in the boiler is fully and reasonably utilized, and the energy of the flue gas is utilized in stages. While ensuring the high efficiency of the supercritical carbon dioxide Brayton cycle, the system is reasonably and effectively coupled with the coal-fired boiler, which solves the problem that the tail low-temperature flue gas cannot Efficient and reasonable use, the problem of heat absorption of the air preheater arranged beyond the specification. At the same time, the present invention can flexibly arrange (multi-stage) reheating cycle and intercooling compression according to needs, so that the application prospect of the overall supercritical carbon dioxide Brayton cycle in engineering practice is greatly improved, and the implementability is remarkable.

Claims (4)

1. a kind of Brayton Cycle system of use supercritical carbon dioxide, it is characterised in that：To boiler hearth heating surface (1) weight New design, heated surface at the end of boiler (4) and air preheater (3) are sequentially arranged in boiler back end ductwork (2)；Boiler furnace is heated Face (1) outlet is connected with working medium turbine (5) entrance, and working medium turbine (5) outlet is connected with high temperature regenerator (6), high temperature regenerator (6) it is connected with middle temperature regenerator (7), middle temperature regenerator (7) is connected with cryogenic regenerator (8), cryogenic regenerator (8) outlet difference It is connected with high temperature compressor (9) and the first condenser (12), high temperature compressor (9) outlet is returned with middle temperature regenerator (7) and low temperature Connected between hot device (8) by pipeline (15), between high temperature regenerator (6) and middle temperature regenerator (7) by pipeline (14) even Connect, high temperature regenerator bypass (16) is reconnected on the pipeline (14) between high temperature regenerator (6) and middle temperature regenerator (7), it is high Warm regenerator bypass (16) by heated surface at the end of boiler (4) and high temperature regenerator (6) outlet be together imported into boiler furnace by Hot face (1)；First condenser (12) is exported to be connected with being cold-pressed mechanism of qi (10) between first, and mechanism of qi (10) outlet and the are cold-pressed between first Two condensers (13) are connected, and the second condenser (13) outlet is connected with being cold-pressed mechanism of qi (11) between second, and mechanism of qi is cold-pressed between second (11) outlet is connected with cryogenic regenerator (8).

2. the Brayton Cycle system of supercritical carbon dioxide is used according to claim 1, it is characterised in that：It is described in height High temperature regenerator bypass (16) is set between warm regenerator (6) and middle temperature regenerator (7), and its inlet temperature is 320 DEG C, outlet temperature Spend for 470 DEG C, so as to be effectively utilized 350 DEG C -500 DEG C of low-temperature flue gas heat, improve system circulation efficiency.

3. the Brayton Cycle system of supercritical carbon dioxide is used according to claim 1, it is characterised in that：It is described two Between cold pressing mechanism of qi use between cold compression, improve the cycle efficieny of the circulatory system, make cooler heat-exchange temperature maintain 30 DEG C- It is good with water-cooling system Temperature Matching between 80 DEG C.

4. the Brayton Cycle system of supercritical carbon dioxide is used according to claim 1, it is characterised in that：The boiler Back-end ductwork is sequentially arranged heated surface at the end of boiler (4) and air preheater (3), makes air preheater heat exchange flue gas in the circulation Scope is at 100 DEG C -350 DEG C, and the design heat exchange amount of correspondence air preheater is identical during heat exchange amount is circulated with coal-fired steam substantially, from And optimize the heat-transfer character of air preheater.