Peak cooling system

Abstract

The invention provides a peak cooling system, which has the working principle that exhaust steam 201 led out from a main exhaust steam pipeline 106 of a host air cooling system is conveyed to a newly added surface type condenser 101 and is subjected to surface heat exchange with circulating cooling water 202 in a pipe bundle of the condenser 101, the heated circulating cooling water 202 is boosted to an air cooling heat dissipation unit 103 of a mechanical ventilation indirect cooling tower 102 by a circulating water pump 104, and the air cooling heat dissipation unit 103 is used for cooling the air cooling heat dissipation unit 103 of the mechanical ventilation indirect cooling tower 102. And the circulating cooling water 202 is cooled by the mechanical ventilation indirect cooling tower 102 and is subjected to surface heat exchange with air 203, the air 203 subjected to heat exchange is discharged into the atmosphere, the circulating cooling water 202 cooled by the mechanical ventilation indirect cooling tower 102 returns into the surface type condenser 101 and is subjected to surface heat exchange with exhaust steam 201, and the process is repeated. The invention aims to provide a peak cooling system suitable for a direct air-cooling thermal generator set, so that the problems that an existing air cooling system is too high in backpressure, insufficient in output, low in cooling efficiency and the like in a high-temperature environment are solved, and the economical efficiency and the safety of the unit are improved.

Description

Technical Field

[0001] The invention relates to the technical field of thermal power generation, and in particular to a peak cooling system for a direct air-cooled thermal power generator set. Background Art

[0002] With the continuous development of the thermal power generation industry, coal-fired power plants, as one of the main power generation methods, are facing increasingly severe pressures to save energy and reduce emissions. In this process, direct air cooling systems have been widely used due to their water-saving advantages, especially in the arid areas of northern my country. However, in the hot season, the operation of direct air-cooled units is affected by high ambient temperature, large wind speed changes, high unit back pressure, and unfavorable wind direction, resulting in varying degrees of impact on the unit's load capacity.

[0003] The main risks of direct air-cooled units in summer operation are as follows: high unit back pressure; large steam flow; turbine overload; reheater overtemperature and overpressure; the unit back pressure is too high, and sudden changes in ambient wind can easily cause the back pressure to rise rapidly, the unit back pressure high protection is activated, and the unit trips; the unit condensate polishing treatment is forced to stop operation, the condensate quality is reduced, and it is easy to cause scaling of the turbine blades, etc.

[0004] Direct air cooling systems are sensitive to different wind directions and wind speeds. Higher lateral wind speeds weaken the fan's operating capacity, and different wind directions can cause heat reflux in the air cooling system. In areas where air cooling units are concentrated, when the load is tight in summer, sudden strong winds due to weather conditions can cause the direct air cooling units to trip due to a sudden increase in operating back pressure, posing a safety hazard to power plants and power grids.

[0005] Direct air-cooled units are often located in the mid-temperate arid zone, which is a typical continental climate feature. It is cold in winter and hot in summer, with a large temperature difference between day and night, and more windy and sandy weather in winter and spring. Due to the harsh natural environment near the power plant site, strong winds and sand, and many willows and poplars around, the floating catkins cause serious blockage of the air-cooled island, and it is impossible to clean it up completely. Direct air-cooled units are affected by the above-mentioned objective external factors such as temperature, strong winds, dust, floating catkins, and the global warming year by year, which reduces the heat exchange performance of the direct air-cooled condenser, resulting in increased back pressure of the turbine operation, limited unit output, increased coal consumption, and reduced condensate quality and thermal economy of the power plant.

[0006] In order to reduce investment costs, the radiator design area margin of direct air-cooling units is often small. In addition, the air-cooling island of direct air-cooling units is built continuously, and there is an obvious interference effect of the unit fan group weakening. Even if the fan runs at full frequency, there is still not enough air volume supply.

[0007] The insufficient cooling capacity of direct air-cooled units in summer directly leads to a serious shortage of the units' peak power generation capacity. Every year, due to the high back pressure in summer and the load limit of the units, they are unable to meet the grid dispatch requirements and face grid penalties.

[0008] The insufficient cooling capacity of direct air-cooled units in summer directly leads to the coal consumption of the units being higher than the advanced values ​​of similar units in the industry, which is far from the target. According to the requirements of the National Development and Reform Commission and other departments on the issuance of "Benchmark Levels and Benchmark Levels in Key Areas of Clean and Efficient Utilization of Coal (2022 Edition) No. 559", and with reference to the access values ​​or limit values ​​in the current national standards, transformation and upgrading and elimination shall be implemented in batches within a time limit. For projects that require clean and efficient utilization of coal, local governments should clarify the time limit for transformation, upgrading and elimination (generally not exceeding 3 years) and the annual transformation and elimination plan, upgrade to above the benchmark level within the prescribed time limit, and strive to reach the benchmark level; projects that cannot be completed on schedule shall be eliminated. The insufficient cooling capacity of direct air-cooled units in summer directly leads to the units facing a severe survival crisis.

[0009] It is emphasized that we should deepen the reform of the power system, accelerate the construction of a new power system that is "clean, low-carbon, safe, sufficient, economical, efficient, coordinated between supply and demand, flexible and intelligent", better promote the revolution in energy production and consumption, and promote the gradual shift from dual control of energy consumption to dual control of carbon emissions. The insufficient cooling capacity of direct air-cooled units in summer directly affects the clean and low-carbon development of the units.

[0010] Due to the inherent construction characteristics of the direct air-cooled unit itself and the influence of long-term operation of dirt, the change of the operating environment conditions of the power plant, the dominant wind in the environmental conditions is the wind behind the furnace. Even in summer, the wind behind the furnace is the majority, and the local wind speed decreases, causing the fan air volume to fail to reach the designed air volume in most cases. The fan group of the unit affects the fan output with great differences, so the heat dissipation between the units is uneven, resulting in high overall back pressure. When the wind direction and wind speed change, the back pressure difference between the units is large. Based on the existence of the above problems, in order to reduce the summer operating back pressure of the unit and increase the summer output of the unit, the heat dissipation capacity of the exhaust cold end of the unit must be increased to reduce the exhaust back pressure of the turbine and achieve the purpose of energy saving and emission reduction, safe and economical operation. Therefore, the equipment added to the direct air-cooled system to solve the above problems is collectively referred to as a peak cooling device. The system composed of these peak cooling devices is called a peak cooling system.

[0011] For air-cooled units, reducing the exhaust pressure of the steam turbine is one of the effective ways to improve the thermal economy of the unit and an effective way to ensure its safe operation. Since direct air-cooled units are easily affected by environmental flow fields and temperature changes, they are particularly affected by high temperatures and strong winds in summer. Therefore, under the premise of ensuring the safe and economical operation of the unit and reducing the standard coal consumption for power supply, increasing the heat dissipation capacity of the cold end of the air-cooled unit has become an effective way to ensure that the direct air-cooled unit can meet the peak demand in summer. At present, the advantages and disadvantages of the existing domestic projects to increase the heat dissipation capacity of the air-cooled island, thereby reducing the operating back pressure of the unit and improving the economy of the unit are as follows:

[0011] Solution 1: Increase the heat dissipation area of ​​the direct air-cooled condenser. The solution of increasing the heat dissipation area of ​​the direct air-cooled condenser can increase the heat dissipation of the air-cooled island, which has a positive effect on reducing the operating back pressure of the unit. In order to ensure that the steam from the turbine exhaust entering each row of air-cooled cooling units is evenly distributed, the steam distribution pipes of the air-cooled system are designed to be symmetrically distributed. The solution of adding a row of heat dissipation units of the same size on the outside of the unit causes the existing steam distribution pipeline to be asymmetric, and a deviation phenomenon occurs when the steam enters each row of air-cooled cooling units, causing uneven heat dissipation performance of the air-cooled cooling units, and even large deviations, which can easily cause unstable phenomena such as back pressure fluctuations. In addition, the tube bundles of some cooling units are prone to freezing and cracking in winter, affecting the safe operation of the unit.

[0012] Plan 1: Increase the heat dissipation area of ​​the direct air-cooled condenser. The construction and installation work is large. The vacuum system (vacuum pump) of the air-cooled unit must also be changed accordingly due to the change in the volume of the air-cooled system, which increases the investment cost and is high in cost. The increase in air-cooled cooling units is limited by site conditions, and the construction difficulty of civil engineering, steel structure, and pipelines is greater than that of new construction. And the heat dissipation performance of the entire air-cooled island is limited.

[0013] Option 2: Add an evaporative condenser system. This option is to connect the exhaust pipe from the original air-cooling island main exhaust pipe, divert part of the exhaust steam to the evaporative condenser, spray cooling water on the surface of the evaporative heat exchange tube bundle, condense the exhaust steam into water, and the condensed water flows to the condensate tank of the air-cooling island exhaust device. The non-condensable gas in the evaporative condenser is discharged by the vacuum system. The cooling water with increased temperature exchanges heat with the cold air during the descent process. The cooled cooling water is collected in the water pool at the bottom of the evaporative condenser and circulated twice through the circulating water pump.

[0014] Option 2: Adding an evaporative condenser system requires spray cooling water. If desalted water is used for spray cooling water, it can effectively prevent scaling of the heat exchanger. However, the price of desalted water is relatively high, and a water quality control and treatment system must be set up. The water consumption is large, resulting in high operating costs and violating the national water use policy. If general industrial water is used for spray cooling water, scaling is easy to form on the surface of the heat exchanger, and dust in the air is easy to clog the heat exchange tube bundle, causing the heat exchange capacity of the cooling device to deteriorate and the heat exchange effect to decrease. Option 2: Spray cooling water uses an open circulating water system, which causes evaporation, wind blowing, and sewage loss of spray cooling water, increasing water consumption. It is not suitable for water-scarce and low-temperature areas. Improper control of antifreeze operation in winter can easily cause serious frost damage. The steam pipeline is relatively long. Evaporative condensers are often arranged close to air-cooled islands, and numerical simulation tests are required to determine whether there is any impact on the air-cooled island.

[0015] Option 3: Add a mechanical ventilation intercooling system for the surface condenser. In this option, the exhaust steam from the main exhaust pipe of the main engine air cooling system is sent to the newly installed surface condenser for surface heat exchange with the cooling water in the condenser tube bundle. The heated cooling water is pressurized by the circulating water pump to the air cooling radiator of the mechanical ventilation intercooling tower for cooling. The cooling water cooled by the intercooling tower returns to the surface condenser for surface heat exchange with the exhaust steam, and the cycle repeats.

[0016] The main features of the scheme 3 to add a surface condenser mechanical ventilation intercooling system are: the mechanical ventilation intercooling system adopts a closed cycle of desalted water, the circulating water does not come into direct contact with the air, and heat is exchanged through convection. In actual operation, there is almost no steam and water loss, no water consumption or very little water consumption, no impact on the water consumption of the whole plant, and excellent water-saving performance. Compared with the evaporative condenser system, the mechanical ventilation intercooling system has a better fan operating environment, no steam and water corrosion, and a low fan failure rate. The mechanical ventilation intercooling system has flexible wind speed selection on the windward side. Properly increasing the wind speed on the windward side can effectively reduce the floor space, and the layout position selection is flexible. The mechanical ventilation intercooling system has flexible adjustment means, and the outlet water temperature can be adjusted by adjusting the fan speed, the opening degree of the shutter, the return fan section, etc. The condenser is arranged near the existing air-cooled exhaust pipe, and the steam pipe is short. Compared with the scheme of increasing the heat dissipation area of ​​the direct air-cooled condenser, the heat exchange effect of the mechanical ventilation intercooling system is less affected by strong winds. The mechanical ventilation intercooling system needs to be equipped with a circulating water pump room and circulating water pipelines. During the specific implementation phase, the layout of existing underground facilities needs to be explored to avoid or minimize the mutual impact between the circulating water pipeline and the original underground pipe network. The mechanical ventilation intercooling system has many fans and consumes a lot of electricity.

[0017] Plan 3 adds a mechanical ventilation intercooling system for the surface condenser. The system is a closed cycle of desalted water. In actual operation, there is almost no steam and water loss, no water consumption or very little water consumption, no impact on the water consumption of the entire plant, and excellent water-saving performance. The cooling system adopts mechanical ventilation, and the heat exchange effect is less affected by strong winds. The wind speed on the windward side can be flexibly selected. Properly increasing the wind speed on the windward side can effectively reduce the floor space. The layout of the mechanical ventilation intercooling tower can be flexibly selected, and the adjustment means are flexible.

[0018] Option 3 adds a mechanical ventilation intercooling system to the surface condenser. By introducing a portion of the exhaust steam into the surface condenser for cooling, and combining it with a mechanical ventilation indirect air cooling tower, the back pressure of the unit can be significantly reduced, the cooling effect can be enhanced, and the output power of the unit can be increased. The peak cooling system is particularly effective during the high temperature period in summer. However, Option 3 still has some shortcomings. For example, Option 3 often requires the modification of the existing unit based on the addition of a mechanical ventilation intercooling system to the surface condenser. In the process of engineering practice, the surface condenser and the mechanical ventilation intercooling tower are limited by the heat exchange efficiency and the existing site, which restricts the layout and scale of the peak cooling system. The addition of a peak cooling system cannot meet the full power requirements of the unit under high temperature conditions in summer, resulting in the unit still being assessed by the power grid. Summary of the invention

[0019] In order to improve the efficiency of the mechanical ventilation intercooling system of the surface condenser as much as possible within a limited space, the present invention proposes a peak cooling system, including a surface condenser using three-dimensional finned tubes and a mechanical ventilation intercooling tower using three-dimensional finned tubes, and a peak cooling system using the above two peak cooling devices.

[0020] A peak cooling system, characterized in that:

[0021] A peak cooling system is composed of a surface condenser 101 using three-dimensional finned tubes 301, a mechanical ventilation intercooler 102 using three-dimensional finned tubes 302, a circulating water pump 104 and a circulating water pipeline 105.

[0022] A peak cooling system, exhaust steam 201 taken from the main exhaust steam pipe 106 of the main engine air cooling system is transported to a newly installed surface condenser 101, and performs surface heat exchange with circulating cooling water 202 in the tube bundle of the condenser 101. The heated circulating cooling water 202 is pressurized by a circulating water pump 104 to the air cooling heat dissipation unit 103 of the mechanical ventilation intercooler 102, and performs surface heat exchange with air 203. The air 203 after heat exchange is discharged into the atmosphere. The circulating cooling water 202 cooled by the mechanical ventilation intercooler 102 returns to the surface condenser 101 and performs surface heat exchange with the exhaust steam 201, and the cycle repeats.

[0023] The condensation tube bundle of the surface condenser 101 is composed of a plurality of tube bundles using three-dimensional finned tubes 301 .

[0024] The three-dimensional fin tube 301 may be a round tube or a parallel flow microchannel flat tube, preferably a parallel flow microchannel flat tube.

[0025] The material of the three-dimensional finned tube 301 can be copper, aluminum alloy, alloy steel and other materials with high thermal conductivity, preferably, 1 series aluminum alloy.

[0026] The interior of the three-dimensional finned tube 301 is circulating cooling water 202, and the exterior is turbine exhaust steam 201 to be cooled. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

[0027] The air-cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102 is composed of a plurality of tube bundles using three-dimensional finned tubes 302 .

[0028] The three-dimensional fin tube 302 may be a round tube or a parallel flow microchannel flat tube, preferably a parallel flow microchannel flat tube.

[0029] The material of the three-dimensional finned tube 302 can be copper, aluminum alloy, alloy steel and other materials with high thermal conductivity, preferably, 6 series aluminum alloy.

[0030] The interior of the three-dimensional finned tube 302 is circulating cooling water 202, and the exterior is air 203. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

[0031] The air-cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102 is composed of a plurality of tube bundles using three-dimensional finned tubes 302. The arrangement of the three-dimensional finned tubes 302 of the air-cooling heat dissipation unit 103 can be a horizontal arrangement scheme in which the length direction of the three-dimensional finned tubes 302 is parallel to the horizontal direction, or a vertical arrangement scheme in which the length direction of the three-dimensional finned tubes 302 is perpendicular to the horizontal direction. The horizontal arrangement scheme of the air-cooling heat dissipation unit 103 can solve the adverse effects of wind speed and wind direction. Preferably, the air-cooling heat dissipation unit 103 selects a horizontal arrangement scheme.

[0032] The three-dimensional finned tubes 301 and 302 are integrally formed by a base tube 303, fins 304 and grooves 305. A plurality of fins 304 arranged in parallel are distributed between the grooves 305. The plurality of fins 304 are evenly distributed along the circumference of the base tube 303 and are arranged in a sequential or staggered manner along the length direction of the base tube 303.

[0033] The cross section of the base tube 303 is an oblate circle 401 , a rectangle 402 or a circle 403 , and the cross section of the fin 304 along the steam or air flow direction is a rectangle or a trapezoid.

[0034] The joint portion between the fin 304 of the base tube 303 and the root of the base tube 303 may be thicker than the top of the fin 304 , or the thickness of the root and the top may be the same.

[0035] The fins 304 of the base tube 303 have the same specifications and sizes and form an angle ɑ with the flow direction of steam or air. The angle ɑ ranges from 30° to 90°, preferably, from 75° to 85°.

[0036] The cross section of the channel 305 of the base pipe 303 is trapezoidal, U-shaped, V-shaped or rectangular.

[0037] The base tube 303 can be directly processed into fins 304 by hot extrusion, cold extrusion, rolling or other methods; or the fins 304 can be first manufactured by hot extrusion, cold extrusion, rolling or other methods and then welded to the base tube 103. Preferably, the fins 304 are directly processed.

[0038] The present invention proposes a peak cooling system, the working principle of which is: the steam turbine exhaust 201 taken from the main exhaust pipe 106 of the main engine air cooling system is sent to the newly installed surface condenser 101, and the three-dimensional finned tube 301 in the surface condenser increases the heat exchange surface area and the turbulence effect, so that the steam turbine exhaust 201 and the circulating cooling water 202 in the condenser 101 tube bundle can exchange heat efficiently, enhance the condensation effect of the steam turbine exhaust 201, and reduce the back pressure of the unit. The heated circulating cooling water 202 is pressurized by the circulating water pump 104 to the air cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102, and exchanges surface heat with the air 203. The three-dimensional finned tube 302 is arranged in the air cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102, which further improves the heat exchange efficiency between the air 203 and the circulating cooling water 202, and increases the overall heat dissipation capacity of the system. The air 203 after heat exchange is discharged into the atmosphere, and the circulating cooling water 202 after cooling in the intercooler returns to the surface condenser 101 and exchanges surface heat with the turbine exhaust 201, and the cycle repeats. The purpose of the present invention is to propose a peak cooling system suitable for direct air-cooled thermal power generating units, thereby solving the problems of excessive back pressure, insufficient output, low cooling efficiency, etc. of the existing air-cooling system in a high temperature environment, and improving the economy and safety of the unit.

[0039] A peak cooling system, characterized in that it comprises the following steps:

[0040] A peak cooling system, exhaust steam 201 taken from the main exhaust steam pipe 106 of the main engine air cooling system is transported to a newly installed surface condenser 101, and performs surface heat exchange with cooling water 202 in the tube bundle of the condenser 101. The heated cooling water 202 is pressurized by a circulating water pump 104 to the air cooling heat dissipation unit 103 of the mechanical ventilation intercooler 102, and performs surface heat exchange with air 203. The air 203 after heat exchange is discharged into the atmosphere. The cooling water 202 cooled by the mechanical ventilation intercooler 102 returns to the surface condenser 101 and performs surface heat exchange with the exhaust steam 201, and the cycle repeats.

[0041] Compared with the existing peak cooling system, the present invention has the following advantages:

[0042] The present invention significantly improves the heat exchange efficiency of the surface condenser and the indirect air cooling tower by adopting the three-dimensional finned tube technology, and solves the problems of low heat dissipation efficiency and large floor space of the existing peak cooling system. BRIEF DESCRIPTION OF THE DRAWINGS The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1 This is a process flow chart of the peak cooling system described in the present invention.

[0044] Figure 1 Description: A peak cooling system, in which the exhaust steam 201 taken from the main exhaust steam pipe 106 of the main engine air cooling system is transported to the newly installed surface condenser 101, and the surface heat exchange is carried out with the circulating cooling water 202 in the tube bundle of the condenser 101. The heated circulating cooling water 202 is pressurized by the circulating water pump 104 to the air cooling heat dissipation unit 103 of the mechanical ventilation intercooler 102, and the surface heat exchange is carried out with the air 203. The air 203 after the heat exchange is discharged into the atmosphere. The circulating cooling water 202 cooled by the mechanical ventilation intercooler 102 returns to the surface condenser 101 and carries out the surface heat exchange with the exhaust steam 201, and the cycle is repeated.

[0045] Figure 1 Legend: 101. Surface condenser 102. Mechanical ventilation cooling tower 103. Air cooling unit 104. Circulating water pump 105. Steam Turbine 106. Main exhaust steam pipeline of main engine air cooling system 109. Air-Condenser 201. Steam turbine exhaust 202. Circulating cooling water 203. Air

[0046] Figure 2 A schematic diagram of the composition of a circular three-dimensional finned tube 301 used in a condensing tube bundle of a surface condenser 101.

[0047] Figure 2 Description: The interior of the circular three-dimensional finned tube 301 is circulating cooling water 202, and the exterior is turbine exhaust steam 201 to be cooled. The flow directions of the two media can be the same or opposite. Preferably, the two media flow in opposite directions.

[0048] Figure 2 Legend: 301. Three-dimensional fin tube 303, base pipe 304, ribs 305, Groove 201. Steam turbine exhaust 202. Circulating cooling water

[0049] Figure 3 A schematic diagram of the structure of the parallel flow microchannel three-dimensional finned tube 301 used in the condensation tube bundle of the surface condenser 101.

[0050] Figure 3 Description: The interior of the parallel flow microchannel three-dimensional fin tube 301 is circulating cooling water 202, and the exterior is turbine exhaust steam 201 to be cooled. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

[0051] Figure 3 Legend: 301. Three-dimensional fin tube 303, base pipe 304, ribs 305, Groove 201. Steam turbine exhaust 202. Circulating cooling water

[0052] Figure 4 The schematic diagram is a diagram of the circular three-dimensional finned tube 302 used in the air-cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102.

[0053] Figure 4 Description: The interior of the circular three-dimensional fin tube 302 is circulating cooling water 202, and the exterior is air 203. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

[0054] Figure 4 Legend: 302. Three-dimensional fin tube 303, base pipe 304, ribs 305, Groove 202. Circulating cooling water 203. Air

[0055] Figure 5 The schematic diagram is a diagram of the parallel flow microchannel three-dimensional fin tube 302 used in the air cooling heat dissipation unit 103 of the mechanical ventilation intercooler 102.

[0056] Figure 5 Description: The interior of the parallel flow microchannel three-dimensional fin tube 302 is circulating cooling water 202, and the exterior is air 203. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

[0057] Figure 5 Legend: 302. Three-dimensional fin tube 303, base pipe 304, ribs 305, Groove 202. Circulating cooling water 203. Air

[0058] Figure 6 It is a schematic diagram of the principle of a vertical arrangement scheme in which the length direction of the three-dimensional fin tube 302 is perpendicular to the horizontal direction.

[0059] Figure 6 Note: The air 203 flows through the air cooling unit 103 from the side, and the air 203 after heat exchange is discharged upward into the atmosphere.

[0060] Figure 6 Legend: 103. Air cooling unit 203. Air

[0061] Figure 7 It is a schematic diagram of the principle of a horizontal arrangement scheme in which the length direction of the three-dimensional finned tube 302 is parallel to the horizontal direction.

[0062] Figure 7 Note: The air 203 is collected from the bottom and flows upward through the air cooling unit 103 from below, and the air 203 after heat exchange is discharged upward into the atmosphere. The horizontal arrangement can solve the adverse effects of wind speed and wind direction.

[0063] Figure 7 Legend: 103. Air cooling unit 203. Air

[0064] Figure 8 This is a working principle diagram of a peak cooling system proposed by the present invention.

[0065] Figure 8 Description: The steam turbine exhaust 201 taken from the main exhaust pipe 106 of the main engine air cooling system is sent to the newly installed surface condenser 101. The three-dimensional finned tube 301 in the surface condenser increases the heat exchange surface area and the turbulence effect, so that the steam turbine exhaust 201 and the circulating cooling water 202 in the condenser 101 tube bundle can exchange heat efficiently, enhance the condensation effect of the steam turbine exhaust 201, and reduce the back pressure of the unit. The heated circulating cooling water 202 is pressurized by the circulating water pump 104 to the air cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102, and exchanges surface heat with the air 203. The three-dimensional finned tube 302 is arranged in the air cooling heat dissipation unit 103 of the mechanical ventilation intercooling tower 102, which further improves the heat exchange efficiency between the air 203 and the circulating cooling water 202 and increases the overall heat dissipation capacity of the system. The air 203 after heat exchange is discharged into the atmosphere, and the circulating cooling water 202 after cooling in the intercooler returns to the surface condenser 101 and exchanges surface heat with the turbine exhaust 201, and the cycle repeats. The purpose of the present invention is to propose a peak cooling system suitable for direct air-cooled thermal power generating units, so as to solve the problems of excessive back pressure, insufficient output, low cooling efficiency, etc. of the existing air-cooling system in a high temperature environment, and improve the economy and safety of the unit. .

[0066] Figure 8 Legend: 101. Surface condenser 102. Mechanical ventilation cooling tower 103. Air cooling unit 104. Circulating water pump 105. Steam Turbine 106. Main exhaust steam pipeline of main engine air cooling system 107. Generator 108. Vacuum Pipeline 109. Air-Condenser 110. Condensate pump 111. Exhaust device 112. Condensate pipe 201. Steam turbine exhaust 202. Circulating cooling water 203. Air 204. Main Steam 205. Vacuum 206. Condensation

[0067] Fig. 9 The fin 304 of the base tube 303 is a schematic diagram showing an angle ɑ with the steam or air flow direction.

[0068] Fig. 9 Legend: 303, base pipe 304, ribs

[0069] Fig.10 Schematic diagram of the cross section of the base tube 303.

[0070] Fig.10 Legend: 303, base pipe 304, ribs 305, Groove DETAILED DESCRIPTION It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0071] The present invention proposes a peak cooling system suitable for a coal-fired power generation unit, comprising the following steps:

[0072] 1. The exhaust steam 201 taken from the main exhaust steam pipe 106 of the main engine air cooling system is transported to the newly installed surface condenser 101.

[0073] 2. Exhaust steam 201 and cooling water 202 in the tube bundle of condenser 101 undergo surface heat exchange.

[0074] 3. The heated cooling water 202 is pressurized by the circulating water pump 104 and sent to the air cooling unit 103 of the mechanical ventilation intercooling tower 102 for cooling.

[0075] 4. The cooling water 202 cooled by the mechanical ventilation intercooler 102 returns to the surface condenser 101 to exchange surface heat with the exhaust steam 201, and the cycle repeats.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A peak cooling system, characterized in that ： A peak cooling system is composed of a surface condenser 101 using three-dimensional finned tubes 301, a mechanical ventilation intercooler 102 using three-dimensional finned tubes 302, a circulating water pump 104 and a circulating water pipeline 105.

2. A peak cooling system according to claim 1, characterized in that: The condensation tube bundle of the surface condenser 101 is composed of a plurality of tube bundles using three-dimensional finned tubes 301 .

3. A peak cooling system according to claim 1, characterized in that: The three-dimensional fin tube 301 may be a round tube or a parallel flow microchannel flat tube, preferably a parallel flow microchannel flat tube.

4. A peak cooling system according to claim 1, characterized in that: The material of the three-dimensional finned tube 301 can be copper, aluminum alloy, alloy steel and other materials with high thermal conductivity, preferably, 1 series aluminum alloy.

5. A peak cooling system according to claim 1, characterized in that: The interior of the three-dimensional finned tube 301 is circulating cooling water 202, and the exterior is turbine exhaust steam 201 to be cooled. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

6. A peak cooling system according to claim 1, characterized in that: The heat dissipation unit 103 of the mechanical ventilation intercooling tower 102 is composed of a plurality of tube bundles using three-dimensional finned tubes 302 .

7. A peak cooling system according to claim 1, characterized in that: The three-dimensional fin tube 302 may be a round tube or a parallel flow microchannel flat tube, preferably a parallel flow microchannel flat tube.

8. A peak cooling system according to claim 1, characterized in that: The material of the three-dimensional finned tube 302 can be copper, aluminum alloy, alloy steel and other materials with high thermal conductivity, preferably, 6 series aluminum alloy.

9. A peak cooling system according to claim 1, characterized in that: The interior of the three-dimensional finned tube 302 is circulating cooling water 202, and the exterior is air 203. The flow directions of the two media can be the same or opposite. Preferably, the flow directions of the two media are opposite.

10. A peak cooling system according to claim 1, characterized in that: The heat dissipation unit 103 of the mechanical ventilation intercooling tower 102 is composed of a plurality of tube bundles using three-dimensional finned tubes 302. The three-dimensional finned tubes 302 of the heat dissipation unit 103 may be arranged in a horizontal manner in which the length direction of the three-dimensional finned tubes 302 is parallel to the horizontal direction, or in a vertical manner in which the length direction of the three-dimensional finned tubes 302 is perpendicular to the horizontal direction. The horizontal arrangement of the heat dissipation unit 103 can solve the adverse effects of wind speed and wind direction. Preferably, the heat dissipation unit 103 is arranged in a horizontal manner.

11. A peak cooling system according to claim 1, characterized in that: The three-dimensional finned tubes 301 and 302 are integrally formed by a base tube 303, fins 304 and grooves 305. A plurality of fins 304 arranged in parallel are distributed between the grooves 305. The plurality of fins 304 are evenly distributed along the circumference of the base tube 303 and are arranged in a sequential or staggered manner along the length direction of the base tube 303.

12. A peak cooling system according to claim 1, characterized in that: The cross section of the base tube 303 of the three-dimensional fin tubes 301 and 302 is oval 401, rectangular 402 or circular 403, and the cross section of the fins 304 of the three-dimensional fin tubes 301 and 302 along the steam or air flow direction is rectangular or trapezoidal.

13. A peak cooling system according to claim 1, characterized in that: The fins 304 of the base tube 303 of the three-dimensional fin tubes 301 and 302 may be thicker at the joint portion with the base tube 303 at the root than at the top of the fins 304 , or the thickness at the root and at the top may be the same.

14. A peak cooling system according to claim 1, characterized in that: The fins 304 of the base tube 303 of the three-dimensional fin tubes 301 and 302 have the same specifications and sizes and form an angle ɑ with the flow direction of steam or air.

15. A peak cooling system according to claim 1, characterized in that: The cross section of the channel 305 of the base tube 303 of the three-dimensional fin tubes 301 and 302 is trapezoidal, U-shaped, V-shaped or rectangular.

16. A peak cooling system according to claim 1, characterized in that: The base tube 303 of the three-dimensional finned tubes 301 and 302 can be directly processed with fins 304 on the base tube 303 by hot extrusion, cold extrusion, rolling or other methods; or the fins 304 can be first manufactured by hot extrusion, cold extrusion, rolling or other methods, and then welded to the base tube 103. Preferably, the fins 304 are directly processed.

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