Steam turbine optimal configuration system arranged at high position and low position

Abstract

The invention provides a steam turbine optimal configuration system arranged at a high position and a low position, which at least comprises a high-position shaft system, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator, a low-pressure cylinder, a generator, a first condenser and a second condenser, wherein the high-position shaft system is arranged close to the elevation position of an inlet header and an outlet header of a superheater and a reheater; the low-pressure cylinder and the generator are arranged on a low-position shaft system; the steam guide pipe is connected between a low-pressure cylinder on the high-position shaft system and the first condenser, the communicating pipe is connected with the steam exhaust end of a medium-pressure cylinder on the high-position shaft system, the steam inlet end of the low-pressure cylinder on the high-position shaft system and the steam inlet end of the low-pressure cylinder on the low-position shaft system, and the valve is arranged at the steam inlet end of the low-pressure cylinder on the low-position shaft system. And the steam in the communicating pipe in front of the steam inlet valve of the low-pressure cylinder on the low-position shaft system enters a heating heat exchange station through a heating valve and a pipeline. By means of the heating valve and a low-pressure cylinder steam inlet valve on the low-position shaft system, steam inlet of a low-pressure cylinder on the low-position shaft system can be adjusted according to specific seasons and loads, so that the commissioning and removing functions of the low-position shaft system are achieved, the steam inlet amount in the heating seasons is adjusted, and the heating steam pressure is maintained. Therefore, the optimal all-season and full-load operation condition is realized, and the purposes of saving energy and reducing consumption are achieved.

Description

Technical Field

[0001] The invention relates to a high-low position arranged steam turbine optimization configuration system, belonging to the field of thermal power generation. Background Art

[0002] In recent years, on the one hand, with the increase of steam parameters and reheat times, the length of high-temperature and high-pressure steam pipelines is relatively long, the investment is large, and it brings pipeline pressure loss and heat loss, affecting the economic efficiency of the unit. On the other hand, with the continuous development of new energy such as wind energy and solar energy, thermal power has been transformed into a supporting and regulating energy source. In order to ensure the safe power supply and power quality of the power grid, coal-fired thermal power units have to take on the main role of peak load regulation, and it is normal for large thermal power units to operate frequently at low load conditions.

[0003] Generally, under the design conditions, the flow of the steam turbine can maintain the best efficiency. However, once it deviates from the design conditions, such as in summer conditions, due to the high circulating water temperature and high unit back pressure, the volume flow of the low-pressure cylinder exhaust steam drops significantly, resulting in a substantial increase in the residual speed loss. In particular, when the unit is in low-load operation, the actual volume flow of the low-pressure cylinder exhaust steam is seriously less than that of the design conditions, resulting in a relatively large surge in the exhaust residual speed loss of the low-pressure cylinder and a significant decrease in efficiency. Similarly, in winter conditions, when the unit is running at high load, the exhaust area of ​​the low-pressure cylinder is often insufficient, causing back pressure blockage problems, resulting in insufficient effective enthalpy drop of the low-pressure cylinder, thus affecting the economy of the unit.

[0004] The design of existing large-scale thermal power generation steam turbines often takes into account the average performance throughout the year. The design operating conditions are all designed according to the average back pressure. The summer and winter conditions that deviate from the design conditions have to sacrifice a certain degree of economy. Otherwise, if designed according to winter conditions, the summer conditions will deviate more seriously from the optimal conditions and the efficiency will be lower. Similarly, if designed according to summer conditions, the low-pressure cylinder will be seriously blocked in the winter conditions, seriously affecting the effective use of low back pressure.

[0005] At present, the existing large units are generally equipped with 1 to 3 low-pressure cylinders. The larger the unit capacity or the lower the design back pressure, the more low-pressure cylinders there are. This is because the length of the last-stage blades of the existing low-pressure cylinders is limited. In order to increase the exhaust area of ​​the low-pressure cylinders, more low-pressure cylinders will be used. For current steam turbine manufacturers, the shaft system is usually arranged in the order of high, medium and low-pressure cylinders. If the number of cylinders is large and a single-axis design is still adopted, the large expansion difference between the dynamic and static flow parts will become an important obstacle. For example, for a 1000MW single-axis secondary reheat unit with low back pressure, three low-pressure cylinders need to be set, and the total number of cylinders reaches 6.

[0006] Considering the above-mentioned existing steam turbine designs, it is difficult to take into account other operating conditions in order to ensure the optimal design conditions, such as low-load operating conditions of the unit in summer or high-load operating conditions of the unit in winter, as well as the excessive differential expansion caused by the conventional shaft arrangement. The technical personnel in this field are committed to developing a system for optimizing the configuration of steam turbines, which can shorten the high-temperature and high-pressure steam pipeline, reduce pipeline investment and pressure loss, thereby improving the economy of the unit. At the same time, it can also control the gap between the dynamic and static low-pressure cylinders, and achieve a low blocking back pressure when the unit is fully loaded in winter, and maintain a high operating efficiency when the unit is under low load in summer, so as to achieve the optimal full-season and full-load operating conditions and achieve the purpose of energy saving and consumption reduction. In addition, it can also take into account the flexible heating needs. Summary of the invention

[0007] To achieve the above-mentioned purpose, the present invention provides a high-low arrangement steam turbine optimization configuration system, the system at least comprising a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder and a generator on a high-position shaft system, and a low-pressure cylinder and a generator on a low-position shaft system, and a first condenser and a second condenser; and an exhaust pipe connecting the low-pressure cylinder on the high-position shaft system and the first condenser, and a connecting pipe connecting the exhaust end of the intermediate-pressure cylinder on the high-position shaft system and the steam inlet end of the low-pressure cylinder and the steam inlet valve of the low-pressure cylinder on the low-position shaft system, characterized in that the high-position shaft system is arranged at an elevation position close to the inlet and outlet manifolds of the superheater and reheater, and the exhaust steam of the high-pressure cylinder on the high-position shaft system enters the steam inlet valve after being reheated once. The exhaust steam of the intermediate pressure cylinder directly enters the low pressure cylinder on the high-level shaft system through the connecting pipe, and enters the low pressure cylinder through the connecting pipe and the valve at the steam inlet end of the low pressure cylinder on the low-level shaft system (called the low pressure cylinder steam inlet valve). The valve can be used to adjust the steam intake into the low pressure cylinder on the low-level shaft system, so as to realize the commissioning and cutting functions of the low-level shaft system and the steam intake amount adjustment in the heating season. Specifically, the low pressure cylinder on the low-level shaft system can be commissioned and cut off according to the load and seasonal conditions of the unit. For example, when the load is low in summer, the low pressure cylinder and the generator on the low-level shaft system are cut off. On the contrary, when the load is high in winter, the low pressure cylinder and the generator on the low-level shaft system are commissioned.

[0008] Further, it is characterized in that the intermediate pressure cylinder of the high-level shaft system is divided into intermediate pressure cylinder one and intermediate pressure cylinder two, the exhaust steam of the high pressure cylinder on the high-level shaft system enters the intermediate pressure cylinder one after one reheating, the exhaust steam of the intermediate pressure cylinder one enters the intermediate pressure cylinder two after two reheating, the intermediate pressure cylinder two directly enters the low pressure cylinder on the high-level shaft system through the connecting pipe, and enters the low pressure cylinder through the connecting pipe and the low pressure cylinder steam inlet valve on the low-level shaft system.

[0009] The high-level shaft system may have one or more low-pressure cylinders; the exhaust steam of the low-pressure cylinders on the high-level shaft system enters the first condenser, and the exhaust steam of the low-pressure cylinders on the low-level shaft system enters the second condenser. The low-pressure cylinders on the low-level shaft system may have one or more low-pressure cylinders.

[0010] Further, it is characterized in that a pipeline is led out from the exhaust steam of the medium-pressure cylinder or the second medium-pressure cylinder on the high-level shaft system and in front of the valve close to the steam inlet end of the low-pressure cylinder on the low-level shaft system and enters the heating heat exchange station through a heating valve, and the heating valve is arranged at a three-way position close to the lead-out.

[0011] The high-low-position steam turbine optimization configuration system of the present invention can achieve the following technical effects: 1. The technical solution of the present invention, since the high-level shaft system is arranged at the elevation position close to the inlet and outlet headers of the superheater and reheater, can achieve a significant shortening of the main steam pipeline, the primary cold reheat pipeline, and the primary hot reheat pipeline (for the secondary reheat unit, it also includes the secondary cold reheat pipeline and the secondary hot reheat pipeline), effectively reducing the pipeline investment, while reducing the pipeline pressure loss and heat dissipation loss, thereby improving the unit economy. In addition, for double-reheat units, especially those with low back pressure that require three low-pressure cylinders, this solution can control the number of cylinders in a single shaft system (high-level shaft system) to within five, and the relative expansion difference between the cylinder and the rotor (referred to as the expansion difference) is relatively small, that is, the gap between the dynamic and static low-pressure cylinders can be made relatively smaller, so higher cylinder efficiency can be obtained, and a short shaft system is also beneficial to the stability of the shaft system and the span layout of the entire plant. For the high-level layout of the high-level shaft system, the weight and length of the cylinders of the high-level shaft system itself directly affect the investment in the plant. Therefore, controlling the length and weight of the high-level shaft system can control the overall investment in the plant.

[0012] In addition, compared with other high-position arrangements, such as a high-position shaft system that only has a high-pressure cylinder, a medium-pressure cylinder, and a generator, the technical solution of the present invention also has a low-pressure cylinder with a large mass (large moment of inertia), so the moment of inertia of the entire shaft system is large, which is beneficial to the transient stability of the power grid and reduces the load rejection and overspeed of the shaft system.

[0013] 2. The exhaust pressure of the intermediate pressure cylinder (or the second intermediate pressure cylinder) is low and the steam specific volume is large. If the exhaust volume is large, the specification of the connecting pipe is usually larger. However, according to the technical solution of the present invention, since the steam intake volume of the low-pressure cylinder on the low-position shaft system is small (for example, 1 / 3) relative to the exhaust volume of the entire intermediate pressure cylinder, the specification of the connecting pipe from the exhaust of the long-distance intermediate pressure cylinder (or the second intermediate pressure cylinder) to the low-pressure cylinder of the low-position shaft system can be set to be relatively small.

[0014] 3. Since the low-pressure cylinder and generator of the low-level shaft system can be put into operation or cut off by the low-pressure cylinder steam inlet valve on the low-level shaft system according to the changes in the unit load and season (or back pressure), it is possible to maintain a low blocking back pressure under high-load conditions in winter, and to relatively reduce the residual speed loss of the running low-pressure cylinder when the unit is operating under low-load conditions in summer, thereby achieving the optimal full-season and full-load operating conditions and achieving the purpose of energy saving and consumption reduction.

[0015] 4. The technical solution of the present invention is to set a heating valve in front of the low-pressure cylinder steam inlet valve of the low-level shaft system, and then connect it to the heating heat exchange station through a steam pipe. Through the heating valve and the low-pressure cylinder steam inlet valve on the low-level shaft system, more flexible adjustment of heating steam can be achieved. Compared with the conventional single shaft system that directly uses the medium-pressure cylinder exhaust steam as the steam for the heating heat exchange station, but cannot cut off the low-pressure cylinder, when the unit load is reduced or the heating steam consumption increases, the conventional method can only be to "hold pressure" through the regulating valve at the steam inlet end of the low-pressure cylinder to meet the heating steam demand, so the throttling loss is large, which has a greater impact on the economy of the entire unit. The technical solution of the present invention can realize the cutting of a single low-pressure cylinder or two low-pressure cylinders through the cooperation of the low-pressure cylinder inlet steam inlet valve and the clutch, thereby achieving the optimal economy of the unit.

[0016] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1, Figure 2, Figure 3, Figure 4, Figure 5 , Figure 6 , Figure 7 , Figure 8 is a system schematic diagram of a specific embodiment of the present invention; Markings in the figure: 1--high-pressure cylinder; 2--medium-pressure cylinder; 3--low-pressure cylinder on the high-level shaft system; 4--low-pressure cylinder on the low-level shaft system; 5--generator on the high-level shaft system; 6--connecting pipe; 7--generator on the low-level shaft system; 8--valve; 9--second condenser; 10--first condenser; 11--steam guide pipe; 12--valve; 13--heating and heat exchange station. Implementation Example

[0018] like Figure 1As shown, it is the first specific embodiment of a high-low position steam turbine optimization configuration system of the present invention. It mainly includes a high-pressure cylinder, a medium-pressure cylinder, two low-pressure cylinders and a generator on the high-position shaft system, and a low-pressure cylinder and a generator on the low-position shaft system. The unit adopts a single reheating method, that is, the exhaust steam of the high-pressure cylinder enters the medium-pressure cylinder after a single reheating, and the exhaust steam of the medium-pressure cylinder passes through the connecting pipe to the two low-pressure cylinders on the high-position shaft system, and enters the low-pressure cylinder on the low-position shaft system through the valve on the connecting pipe. Among them, the high-level shaft system is arranged at an elevation position close to the inlet and outlet headers of the superheater and reheater, such as 65~85 meters (the elevation positions of the inlet and outlet headers of the superheater and reheater of different types of power plant units will have certain differences), and the first condenser is arranged at the 0-meter layer, so that the exhaust steam of the low-pressure extraction arranged at a high position directly enters the first condenser through a long-distance steam guide pipe; while the low-pressure cylinder and generator on the low-level shaft system are arranged at a conventional low position, such as 17 meters, and the second condenser is arranged at the 0-meter layer. Since the high-pressure cylinder and the medium-pressure cylinder are arranged at a high position, the main steam pipeline, the primary cold re-pipeline, and the primary hot re-pipeline can be greatly shortened, which can shorten the length of these high-temperature and high-pressure pipelines, reduce pipeline investment and pressure loss, and thus improve the unit economy.

[0019] In addition, the steam inlet volume of the low-pressure cylinder on the low-level shaft system can be flexibly set, for example, it can be set according to 1 / 3 of the total medium-pressure cylinder exhaust volume. When the load is high in winter, the low-level shaft system can be fully put into operation to ensure the operation of the three low-pressure cylinders, thereby having sufficient exhaust area and ensuring a lower blocking back pressure. When the load is low in summer, the low-level shaft system can be cut off, thereby significantly reducing the residual speed loss of the low-pressure cylinder on the high-level shaft system. It is estimated that the internal efficiency can be relatively improved by at least 4%. At the same time, the lower the unit load and the higher the circulating water temperature, the greater the relative benefit of cutting off the low-level shaft system. Example

[0020] like Figure 2As shown, it is the second specific embodiment of a high-low position steam turbine optimization configuration system of the present invention. It mainly includes a high-pressure cylinder, a medium-pressure cylinder 1, a medium-pressure cylinder 2, two low-pressure cylinders and a generator on the high-position shaft system, and a low-pressure cylinder and a generator on the low-position shaft system. The unit adopts a double reheating method, that is, the exhaust steam of the high-pressure cylinder enters the medium-pressure cylinder 1 after one reheating, and the exhaust steam of the medium-pressure cylinder 1 enters the medium-pressure cylinder 2 after the second reheating, and the exhaust steam of the medium-pressure cylinder 2 enters the two low-pressure cylinders on the high-position shaft system through the connecting pipe, and enters the low-pressure cylinder on the low-position shaft system through the valve on the connecting pipe. Among them, the high-level shaft system is arranged at an elevation position close to the inlet and outlet headers of the superheater and reheater, for example, at an elevation of 65 to 85 meters (the elevation positions of the inlet and outlet headers of the superheater and reheater of different types of power plant units will have certain differences), and the first condenser is arranged at the 0-meter layer, so that the exhaust steam drawn from the low-pressure pump arranged at a high position directly enters the condenser through a long-distance steam guide pipe; while the low-pressure cylinder and generator on the low-level shaft system are arranged at a conventional low position, for example, 17 meters, and the second condenser is arranged at the 0-meter layer. Since the high-pressure cylinder, the medium-pressure cylinder 1, and the medium-pressure cylinder 2 are all arranged at a high position, the main steam pipeline, the primary cold re-pipeline, the primary hot re-pipeline, the secondary cold re-pipeline, and the secondary hot re-pipeline can be greatly shortened, which reduces the pipeline investment and pressure loss, thereby improving the unit economy. Compared with Example 1, the high-level shaft system has one more cylinder, and a two-time reheating method is adopted. The switching of the low-pressure cylinder of the low-level shaft system is the same as Example 1, which will not be repeated here. Example

[0021] like Figure 3 As shown, it is the third specific embodiment of the present invention. This scheme is based on Example 1 and further sets the steam inlet pipe and valve from the medium-pressure cylinder exhaust (before the valve of the low-pressure cylinder steam inlet pipe of the low-level shaft system) to the heating heat exchange station. Compared with the conventional single shaft system directly using the medium-pressure cylinder exhaust as the heating heat exchange station, since this technical scheme sets the adjustable (or switched) low-pressure cylinder of the low-level shaft system, when the steam inlet pressure of the heating heat exchange station is low, the low-pressure cylinder on the low-level shaft system can be reduced or even cut off, thereby increasing the steam inlet pressure and flow rate entering the heat exchange station to meet the needs of the heating heat exchange station. Compared with the conventional method of using the exhaust steam of the medium-pressure cylinder as the steam for the heating heat exchange station, since the low-pressure cylinder cannot be removed, when the unit load decreases or the heating steam consumption increases, other methods can only be used, such as setting a regulating valve on the exhaust steam pipeline of the medium-pressure cylinder to "hold pressure" to meet the heating steam demand, so the throttling loss is large, which has a great impact on the economy of the entire unit. The technical solution of the present invention can meet the heating steam demand by simply adjusting the steam inlet valve of the low-pressure cylinder inlet on the low-position shaft system, and the throttling loss is small. Therefore, the heating method of this technical solution is more flexible.

[0022] Furthermore, the heating valve is arranged near the three-way position of the lead-out and before the low-pressure cylinder steam inlet valve. The advantage is that, on the one hand, when the low-pressure cylinder is completely cut off, the exhaust steam of the medium-pressure cylinder all enters the heating heat exchange station, which can avoid the "blind section" of the pipeline where no flow occurs, and maintain the hot standby state of the low-pressure cylinder steam inlet pipeline. On the other hand, it reduces the harmful volume between the high-level machine shaft system and the heating steam exchange station, avoiding the steam backflow from the heating heat exchange station to the high-level machine shaft system.

[0023] Other aspects are the same as those in Example 1 and will not be described in detail here. Example

[0024] like Figure 4 As shown, it is the fourth specific embodiment of the present invention. This scheme is based on Example 2 and further sets the steam inlet pipe and valve from the medium-pressure cylinder exhaust (before the valve of the low-pressure cylinder steam inlet pipe of the low-level shaft system) to the heating heat exchange station. Compared with the conventional single shaft system directly using the medium-pressure cylinder exhaust as the heating heat exchange station, since this technical scheme sets an adjustable (or switched) low-pressure cylinder of the low-level shaft system, when the steam inlet pressure of the heating heat exchange station is low, the low-pressure cylinder on the low-level shaft system can be reduced or even cut off, thereby increasing the steam inlet pressure and flow entering the heat exchange station to meet the needs of the heating heat exchange station. Therefore, the heating method of this technical scheme is more flexible.

[0025] Furthermore, the heating valve is arranged near the three-way position of the lead-out and before the low-pressure cylinder steam inlet valve. The advantage is that, on the one hand, when the low-pressure cylinder is completely cut off, the exhaust steam of the two medium-pressure cylinders all enters the heating heat exchange station, which can avoid the "blind section" of the pipeline where no flow occurs, and maintain the hot standby state of the low-pressure cylinder steam inlet pipeline. On the other hand, it reduces the harmful volume between the high-level machine shaft system and the heating steam exchange station, avoiding the steam backflow from the heating heat exchange station to the high-level machine shaft system.

[0026] Other aspects are the same as those in Example 2 and will not be described in detail here. Example

[0027] like Figure 5 As shown, it is the fifth specific embodiment of the present invention. The difference between this scheme and Example 1 is that the high-level shaft system only includes one low-pressure cylinder, and the other arrangements are consistent, and the operation mode of switching the low-pressure cylinder is consistent. Compared with Example 1, this scheme is suitable for relatively high back pressure because there is one less low-pressure cylinder, and the exhaust area of ​​the low-pressure cylinder does not need to be made very large. In this way, the high-level shaft system is relatively shorter, which can reduce investment and make the axial clearance of the high-level shaft system smaller and better. Others are consistent with Example 1 and will not be repeated here. Example

[0028] like Figure 6As shown, it is the sixth specific embodiment of the present invention. The difference between this scheme and Example 3 is that the high-level shaft system only includes one low-pressure cylinder, and the other arrangements are consistent, and the operation mode of switching the low-pressure cylinder is consistent. Compared with Example 3, this scheme is suitable for relatively high back pressure because there is one less low-pressure cylinder, and the exhaust area of ​​the low-pressure cylinder does not need to be made very large. In this way, the high-level shaft system is relatively shorter, which can reduce investment and make the axial clearance of the high-level shaft system smaller and better. The rest is consistent with Example 3 and will not be repeated here. Example

[0029] like Figure 7 As shown, it is the seventh specific embodiment of the present invention. The difference between this scheme and Example 2 is that the high-level shaft system only includes one low-pressure cylinder, and the other arrangements are consistent, and the operation mode of switching the low-pressure cylinder is consistent. Compared with Example 2, this scheme is suitable for relatively high back pressure because there is one less low-pressure cylinder, and the exhaust area of ​​the low-pressure cylinder does not need to be made very large. In this way, the high-level shaft system is relatively shorter, which can reduce investment and make the axial clearance of the high-level shaft system smaller and better. Others are consistent with Example 2 and will not be repeated here. Example

[0030] like Figure 8 As shown, it is the eighth specific embodiment of the present invention. The difference between this scheme and Example 4 is that the high-level shaft system only includes one low-pressure cylinder, and the other arrangements are consistent, and the operation mode of switching the low-pressure cylinder is consistent. Compared with Example 4, this scheme is suitable for relatively high back pressure because there is one less low-pressure cylinder, and the exhaust area of ​​the low-pressure cylinder does not need to be made very large. In this way, the high-level shaft system is relatively shorter, which can reduce investment and make the axial clearance of the high-level shaft system smaller and better. The rest is consistent with Example 4 and will not be repeated here.

[0031] The above describes in detail the preferred specific embodiments of the present invention. It should be noted that there can be many combinations of the number of medium-pressure cylinders in the high-level shaft system, the number of low-pressure cylinders, and the number of low-pressure cylinders in the low-level shaft system. It should be understood that ordinary technology in this field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in this technical field through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the existing technology should be within the scope of protection determined by the claims.

Claims

1. A high-low arrangement steam turbine optimization configuration system, characterized in that: The system at least includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder and a generator on the high-level shaft system, and a low-pressure cylinder and a generator on the low-level shaft system, and a first condenser and a second condenser; and an exhaust pipe connecting the low-pressure cylinder on the high-level shaft system and the first condenser, and a connecting pipe connecting the exhaust end of the intermediate-pressure cylinder on the high-level shaft system and the steam inlet end of the low-pressure cylinder on the high-level shaft system and the steam inlet end of the low-pressure cylinder on the low-level shaft system, and a valve arranged at the steam inlet end of the low-pressure cylinder on the low-level shaft system, characterized in that the high-level shaft system The system is arranged at an elevation position close to the inlet and outlet manifolds of the superheater and reheater. The exhaust steam of the high-pressure cylinder on the high-level shafting enters the medium-pressure cylinder after one reheating. The exhaust steam of the medium-pressure cylinder directly enters the low-pressure cylinder on the high-level shafting through the connecting pipe, and enters the low-pressure cylinder through the valve at the steam inlet end of the low-pressure cylinder on the low-level shafting. The exhaust steam of the low-pressure cylinder on the high-level shafting enters the first condenser, and the exhaust steam of the low-pressure cylinder on the low-level shafting enters the second condenser.

2. The system according to claim 1, characterized in that The intermediate pressure cylinder of the high-position shaft system is divided into intermediate pressure cylinder one and intermediate pressure cylinder two. The exhaust steam of the high-pressure cylinder on the high-position shaft system enters the intermediate pressure cylinder one after one reheating, and the exhaust steam of the intermediate pressure cylinder one enters the intermediate pressure cylinder two after two reheating. The intermediate pressure cylinder two directly enters the low-pressure cylinder on the high-position shaft system through the connecting pipe, and enters the low-pressure cylinder through the valve at the steam inlet end of the low-pressure cylinder on the low-position shaft system.

3. The system according to claim 1, characterized in that The number of the low-pressure cylinders of the high-position shaft system may be one or more, and the number of the low-pressure cylinders of the low-position shaft system may be one or more.

4. The system according to claim 2, characterized in that The high-level shaft system may include one or more low-pressure cylinders, and the low-level shaft system may include one or more low-pressure cylinders.

5. The system according to claim 3, characterized in that The exhaust steam of the medium-pressure cylinder on the high-level shaft system is close to the valve at the steam inlet end of the low-pressure cylinder on the low-level shaft system, and a pipeline is led out and enters the heating heat exchange station through a heating valve. The heating valve is arranged at a three-way position close to the lead-out.

6. The system according to claim 4, characterized in that The exhaust steam of the second medium-pressure cylinder on the high-level shaft system is close to the valve at the steam inlet end of the low-pressure cylinder on the low-level shaft system, and a pipeline is led out and enters the heating heat exchange station through a heating valve. The heating valve is arranged at a three-way position close to the lead-out.

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