阅读说明：本技术 双机回热系统及其功率调节方法 (Double-machine regenerative system and power adjusting method thereof ) 是由 王开晶 李冲 王奉沛 于 2019-09-29 设计创作，主要内容包括：本发明提出了一种双机回热系统,包括锅炉、发电装置、凝汽器、回热装置和控制装置,发电装置的一端和锅炉相连通,发电装置的另一端和凝汽器相连通,控制装置中引入了AGC或一次调频负荷调节信号,发电装置包括汽轮机超高压汽缸、汽轮机高压汽缸、汽轮机中压汽缸、汽轮机低压汽缸、发电机、回热式小汽轮机和小发电机,回热装置包括低压加热器、除氧器和高压加热器,汽轮机低压汽缸上设置有第二抽汽口,回热式小汽轮机上设置有第一抽汽口,借此,本发明具有既降低了机组抽汽过热度、降低不可逆损失优点,又能提高AGC、一次调频动作品质的优点,在主汽轮发电机机组快速升降负荷时,有利于主汽压力稳定,有利于参数控制的优点。(The invention provides a double-machine regenerative system, which comprises a boiler, a power generation device, a condenser, a regenerative device and a control device, wherein one end of the power generation device is communicated with the boiler, the other end of the power generation device is communicated with the condenser, AGC (automatic gain control) or primary frequency modulation load regulation signals are introduced into the control device, the power generation device comprises a turbine ultrahigh pressure cylinder, a turbine high pressure cylinder, a turbine medium pressure cylinder, a turbine low pressure cylinder, a generator, a regenerative small turbine and a small generator, the regenerative device comprises a low pressure heater, a deaerator and a high pressure heater, a second steam extraction opening is arranged on the turbine low pressure cylinder, and a first steam extraction opening is arranged on the regenerative small turbine, so that the double-machine regenerative system has the advantages of reducing the superheat degree of steam extraction of a unit, reducing irreversible loss and improving the AGC and primary frequency modulation action quality, the pressure of the main steam is stabilized, and the parameter control is facilitated.)

1. A double-machine regenerative system is characterized by comprising a boiler, a power generation device, a condenser, a regenerative device and a control device, wherein one end of the power generation device is communicated with the boiler, and the other end of the power generation device is communicated with the condenser;

the power generation device comprises a main steam turbine generator set and a regenerative small steam turbine generator set, wherein the main steam turbine generator set comprises a steam turbine ultrahigh pressure cylinder, a steam turbine high pressure cylinder, a steam turbine medium pressure cylinder, a steam turbine low pressure cylinder and a generator, the turbine ultrahigh pressure cylinder, the turbine high pressure cylinder, the turbine medium pressure cylinder and the turbine low pressure cylinder form a main turbine, the main turbine and the generator are coaxially connected to form a large turbine generator set together, the regenerative small turbine generator set comprises a water feeding pump, a regenerative small turbine and a small generator, one end of the small backheating steam turbine is coaxially connected with the water feeding pump, the other end of the small backheating steam turbine is coaxially connected with the small generator to jointly form a small backheating steam turbine generator set, and a speed regulating device is connected between the water feeding pump and the small backheating steam turbine;

the steam inlet of the turbine ultrahigh-pressure cylinder is communicated with a first steam outlet of the boiler, a first adjusting valve and a gas supplementing valve are arranged between the steam inlet of the turbine ultrahigh-pressure cylinder and the first steam outlet of the boiler, the first adjusting valve and the gas supplementing valve are respectively and electrically connected with a control device, the steam outlet of the turbine ultrahigh-pressure cylinder is respectively communicated with the steam inlet of the boiler, the steam inlet of a heat regenerating device and the steam inlet of a heat regenerating small turbine, the steam inlet of the turbine high-pressure cylinder is communicated with a second steam outlet of the boiler, the steam outlet of the turbine high-pressure cylinder is communicated with the steam inlet of a medium-pressure turbine, the steam inlet of the turbine low-pressure cylinder is communicated with the steam outlet of a medium-pressure cylinder of the turbine, the steam outlet of the turbine low-pressure cylinder is communicated with the steam inlet of a condenser, and a second steam extraction port is arranged on the turbine low-pressure cylinder, a second adjusting valve is arranged between the steam inlet of the small backheating steam turbine and the steam outlet of the ultrahigh pressure cylinder of the steam turbine, the second adjusting valve is electrically connected with the control device, the steam outlet of the small backheating steam turbine is respectively communicated with the steam inlet of the backheating device and the steam inlet of the condenser, and the small backheating steam turbine is provided with a first steam extraction port;

the heat recovery device comprises a high-pressure heater, a deaerator and a low-pressure heater, wherein a water inlet of the low-pressure heater is communicated with a water outlet of the condenser, a water outlet of the low-pressure heater is communicated with a water inlet of the deaerator, a steam inlet of the low-pressure heater is communicated with a second steam extraction port, a water inlet of the high-pressure heater is communicated with a water outlet of the deaerator, a water outlet of the high-pressure heater is communicated with a water inlet of the boiler, and a steam inlet of the high-pressure heater and a steam inlet of the deaerator are respectively communicated with a first steam extraction port.

2. The dual-machine regenerative system according to claim 1, wherein the turbine intermediate-pressure cylinder is of a symmetrical split-flow type, two steam outlets are provided on two sides of the turbine intermediate-pressure cylinder, and the two steam outlets are communicated with the steam inlet of the turbine low-pressure cylinder after being merged.

3. The dual-machine regenerative system according to claim 1, wherein the turbine low-pressure cylinder is of a symmetrical split-flow type, two steam outlets are provided on two sides of the turbine low-pressure cylinder, and the two steam outlets are communicated with the steam inlet of the condenser.

4. The dual-machine regenerative system according to claim 1, wherein the high-pressure heater comprises a number 1 high-pressure heater, a number 2 high-pressure heater, a number 3 high-pressure heater, a number 4 high-pressure heater, a number 5 high-pressure heater and a number 6 high-pressure heater, wherein a water outlet of the number 1 high-pressure heater is communicated with a water inlet of the boiler, a steam inlet of the number 1 high-pressure heater is communicated with a steam outlet of an ultra-high pressure cylinder of the steam turbine, a water inlet of the number 6 high-pressure heater is communicated with a water outlet of a deaerator, steam pressures in the number 2 high-pressure heater to the number 6 high-pressure heater are sequentially arranged from high to low, the low-pressure heaters comprise a number 8 low-pressure heater, a number 9 low-pressure heater, a number 10 low-pressure heater, a number 11 low-pressure heater and a number 12 low, the steam inlet of the No. 8 low-pressure heater is communicated with the steam outlet of the backheating type small steam turbine, the steam inlet of the No. 9 low-pressure heater is communicated with the steam outlet of the backheating type small steam turbine, the water inlet of the No. 12 low-pressure heater is communicated with the water outlet of the condenser, and the steam pressures in the No. 9 low-pressure heater and the No. 12 low-pressure heater are sequentially arranged from high to low.

5. The dual-machine regenerative system according to claim 4, wherein the first steam extraction port comprises a No. 1 steam extraction port, a No. 2 steam extraction port, a No. 3 steam extraction port, a No. 4 steam extraction port, a No. 5 steam extraction port and a No. 6 steam extraction port, wherein the No. 1 steam extraction port is communicated with the steam inlet of the No. 2 high-pressure heater, the No. 2 steam extraction port is communicated with the steam inlet of the No. 3 high-pressure heater, the No. 3 steam extraction port is communicated with the steam inlet of the No. 4 high-pressure heater, the No. 4 steam extraction port is communicated with the steam inlet of the No. 5 high-pressure heater, the No. 5 steam extraction port is communicated with the steam inlet of the No. 6 high-pressure heater, and the No. 6 steam extraction port is communicated with the steam inlet of the deaerator.

6. The dual-machine regenerative system according to claim 4, wherein the second steam extraction port comprises a No. 7 steam extraction port, a No. 8 steam extraction port, a No. 9 steam extraction port and a No. 10 steam extraction port, wherein the No. 7 steam extraction port is communicated with the steam inlet of the No. 9 low-pressure heater, the No. 8 steam extraction port is communicated with the steam inlet of the No. 10 low-pressure heater, the No. 9 steam extraction port is communicated with the steam inlet of the No. 11 low-pressure heater, and the No. 10 steam extraction port is communicated with the steam inlet of the No. 12 low-pressure heater.

7. The dual-machine regenerative system according to claim 1, wherein the first steam outlet of the boiler is communicated with the steam inlet of the turbine ultra-high pressure cylinder through a main steam pipeline, the first air regulating valve and the air compensating valve are disposed on the main steam pipeline, and the second steam outlet of the boiler is communicated with the steam inlet of the turbine high pressure cylinder through a reheat steam pipeline.

8. A power regulation method of a double-machine regenerative system is characterized in that an AGC (automatic gain control) or primary frequency modulation load regulation signal is introduced into a control device, and the control device controls a first regulating valve and a second regulating valve according to an AGC or primary frequency modulation load instruction.

9. The power regulation method of the dual-machine regenerative system according to claim 8, wherein when the AGC or primary frequency modulation load command is reduced, the load command is sent to the control device, and the control device controls the first modulating valve to be closed to be small, and simultaneously opens the second modulating valve to increase the steam admission of the small regenerative turbine, so as to meet the power grid requirement.

10. The power regulation method of the dual-machine regenerative system according to claim 8, wherein when the AGC or primary frequency modulation load command is increased, the load command is sent to the control device, and the control device controls the first regulating valve to be opened to be large, and simultaneously, the second regulating valve is closed to be small, so that steam admission of the regenerative small steam turbine is reduced, and the power grid requirement is met.

Technical Field

The invention belongs to the technical field of thermal power generation, and particularly relates to a double-machine regenerative system and a power adjusting method thereof.

Background

At present, with the continuous improvement of the high-temperature performance of materials, the steam parameters of a coal-fired power generating unit are continuously improved so as to obtain higher cycle efficiency, further reduce the coal consumption of the unit and reduce the emission of greenhouse gases and other pollutants. Improving steam parameters is one of the most direct ways to improve the cycle efficiency of the power generation system.

With the continuous development of the power industry, the power generation proportion of new energy sources such as wind power and solar energy is increased year by year, but the adjustability of new energy power sources is poor, the power of a connecting line between power grids is high, and once the power is tripped, the load of a receiving-end power grid power source needs to be increased rapidly. For the reasons, the power grid has higher and higher requirements on the primary frequency modulation quality and the load regulation capacity of the unit. The large-capacity turbine set adopts double reheating, the reheating volume is large, the load regulation is slow, and the large-capacity turbine generally has no regulation stage and adopts throttling steam distribution. In order to reduce throttling loss, the steam turbine regulating valve is nearly fully opened, so that the load-lifting speed of a unit is low, the quality of AGC (automatic gain control) and primary frequency modulation actions is poor, and the qualification rate of the primary frequency modulation actions is low. According to the relevant regulations of the power grid, the qualification rate of the primary frequency modulation action of the unit is lower than 80%, the economic assessment is performed, and the economic loss is brought to a power plant.

However, as the steam parameters are improved, the superheat degree of the regenerative extraction steam is increased, the irreversible loss of heat exchange in the regenerative heater is increased, the gain caused by the increase of the steam parameters is weakened, and the higher the steam parameters, the more prominent the contradiction is.

Disclosure of Invention

The invention provides a double-machine regenerative system and a power adjusting method thereof, which not only reduce the overheating of steam extraction of a machine set and the irreversible loss, but also improve the action quality of AGC and primary frequency modulation and improve the safety of a power grid.

The technical scheme of the invention is realized as follows: a double-machine regenerative system comprises a boiler, a power generation device, a condenser, a regenerative device and a control device, wherein one end of the power generation device is communicated with the boiler, and the other end of the power generation device is communicated with the condenser;

the power generation device comprises a main steam turbine generator set and a backheating type small steam turbine generator set, wherein the main steam turbine generator set comprises a steam turbine ultrahigh-pressure cylinder, a steam turbine high-pressure cylinder, a steam turbine medium-pressure cylinder, a steam turbine low-pressure cylinder and a generator;

the steam inlet of the turbine ultrahigh-pressure cylinder is communicated with a first steam outlet of a boiler, a first air regulating valve and an air compensating valve are arranged between the steam inlet of the turbine ultrahigh-pressure cylinder and the first steam outlet of the boiler, the first air regulating valve and the air compensating valve are respectively and electrically connected with a control device, the steam outlet of the turbine ultrahigh-pressure cylinder is respectively communicated with the steam inlet of the boiler, the steam inlet of a heat regenerating device and the steam inlet of a small heat regenerating turbine, the steam inlet of the turbine high-pressure cylinder is communicated with a second steam outlet of the boiler, the steam outlet of the turbine high-pressure cylinder is communicated with the steam inlet of a medium-pressure cylinder of the turbine, the steam inlet of the turbine low-pressure cylinder is communicated with the steam outlet of a medium-pressure cylinder of the turbine, the steam outlet of the turbine low-pressure cylinder is communicated with the steam inlet of a condenser, a second steam extraction port is arranged on the turbine low-pressure cylinder, and a second air regulating valve is arranged between the steam inlet of the small heat regenerating turbine and the steam outlet, the second regulating valve is electrically connected with the control device, a steam outlet of the small regenerative steam turbine is respectively communicated with a steam inlet of the regenerative device and a steam inlet of the condenser, and a first steam extraction port is arranged on the small regenerative steam turbine;

the heat recovery device comprises a high-pressure heater, a deaerator and a low-pressure heater, wherein a water inlet of the low-pressure heater is communicated with a water outlet of the condenser, a water outlet of the low-pressure heater is communicated with a water inlet of the deaerator, a steam inlet of the low-pressure heater is communicated with a second steam extraction port, a water inlet of the high-pressure heater is communicated with a water outlet of the deaerator, a water outlet of the high-pressure heater is communicated with a water inlet of the boiler, and a steam inlet of the high-pressure heater and a steam inlet of the deaerator are respectively communicated with a first steam.

The small regenerative steam turbine coaxially drives the small generator to jointly form a small regenerative steam turbine generator set, the steam turbine ultrahigh pressure cylinder, the steam turbine high pressure cylinder, the steam turbine medium pressure cylinder and the steam turbine low pressure cylinder form a large steam turbine, the large steam turbine and the generator are coaxially connected to jointly form a large steam turbine generator set, and a double-machine regenerative power generation system formed by the large steam turbine generator set and the small steam turbine generator set is realized.

Steam in a boiler enters the turbine ultrahigh-pressure cylinder through a steam inlet of the turbine ultrahigh-pressure cylinder to do work, part of the steam discharged from the turbine ultrahigh-pressure cylinder returns to the boiler again to be heated, part of the steam enters the high-pressure heater to heat feed water, the other part of the steam enters the regenerative small turbine through a steam inlet of the regenerative small turbine to do work, meanwhile, the steam in the regenerative small turbine enters the high-pressure heater through a first steam extraction port to heat the feed water, the steam reheated by the boiler enters the turbine high-pressure cylinder through a steam inlet of the turbine high-pressure cylinder to do work, the steam discharged from the turbine high-pressure cylinder enters the turbine medium-pressure cylinder to do work, the steam discharged from the turbine medium-pressure cylinder enters the turbine low-pressure cylinder to do work, the steam discharged from the turbine low-pressure cylinder enters the condenser to be condensed water, meanwhile, steam in the low-pressure cylinder of the steam turbine enters the low-pressure heater through the second steam extraction port, and condensed water in the condensed water device sequentially passes through the low-pressure heater, the deaerator and the high-pressure heater and is conveyed to the boiler for cyclic utilization. Because the prior art often adopts the medium-pressure cylinder of the steam turbine to extract steam, which causes the problem of overlarge extracted steam superheat, the invention adopts the regenerative small steam turbine and the low-pressure cylinder of the steam turbine to extract steam respectively, thereby solving the problem of loss caused by overlarge extracted steam superheat.

In a preferred embodiment, the steam turbine medium-pressure cylinder is in a symmetrical split-flow type, two steam outlets are arranged on two sides of the steam turbine medium-pressure cylinder, and the two steam outlets are communicated with the steam inlet of the steam turbine low-pressure cylinder after being merged.

The reason that the symmetrical split flow type is adopted by the medium-pressure cylinder of the steam turbine is that the steam flow passing through each stage of blades of the medium-pressure cylinder of the steam turbine is increased along with the increase of the capacity of a unit, so that the length of the blades is increased to ensure the passing of the steam flow. However, the blades are too long and are limited by the strength of materials under the high-speed rotation of the steam turbine, and the blade fracture accident is easy to happen, so that the medium-pressure cylinders of the steam turbine of the large-capacity unit adopt a symmetrical split flow type, the lengths of all stages of blades of the medium-pressure cylinders of the steam turbine are shortened, the output of the unit is ensured, and the axial thrust can be reduced.

As a preferred implementation mode, the high-pressure heater sequentially comprises a No. 1 high-pressure heater, a No. 2 high-pressure heater, a No. 3 high-pressure heater, a No. 4 high-pressure heater, a No. 5 high-pressure heater and a No. 6 high-pressure heater, wherein the water outlet of the No. 1 high-pressure heater is communicated with the water inlet of the boiler, the steam inlet of the No. 1 high-pressure heater is communicated with the steam outlet of the ultrahigh-pressure cylinder of the steam turbine, the water inlet of the No. 6 high-pressure heater is communicated with the water outlet of the deaerator, the steam pressures in the No. 2 high-pressure heater to the No. 6 high-pressure heater are arranged from high to low, the low-pressure heater sequentially comprises a No. 8 low-pressure heater, a No. 9 low-pressure heater, a No. 10 low-pressure heater, a No. 11 low-pressure heater and a No. 12 low, the steam inlet of the No. 9 low-pressure heater is communicated with the steam outlet of the backheating type small steam turbine, the water inlet of the No. 12 low-pressure heater is communicated with the condensed water device, and the steam pressure in the No. 9 low-pressure heater and the No. 12 low-pressure heater is arranged from high to low.

During condensate water that condenses through the condenser got into No. 12 low pressure feed water heaters, low pressure feed water heater heated condensate water, and the condensate water after the heating got into the oxygen-eliminating device by No. 8 low pressure feed water heaters, and the oxygen and other gas that the oxygen-eliminating device was used for getting rid of the condensate water, and the water in the second water-feeding pump will the oxygen-eliminating device is squeezed into high pressure feed water heater, and high pressure feed water heater heats the feedwater, and the feedwater after the heating gets into the boiler by No. 1 high pressure feed water heater.

As a preferred embodiment, the first steam extraction port comprises a steam extraction port 1, a steam extraction port 2, a steam extraction port 3, a steam extraction port 4, a steam extraction port 5 and a steam extraction port 6, wherein the steam extraction port 1 is communicated with the steam inlet of the high-pressure heater 2, the steam extraction port 2 is communicated with the steam inlet of the high-pressure heater 3, the steam extraction port 3 is communicated with the steam inlet of the high-pressure heater 4, the steam extraction port 4 is communicated with the steam inlet of the high-pressure heater 5, the steam extraction port 5 is communicated with the steam inlet of the high-pressure heater 6, and the steam extraction port 6 is communicated with the steam inlet of the deaerator.

The first steam extraction port is used for sending steam in the small regenerative steam turbine to the high-pressure heater and the deaerator and further heating feed water in the high-pressure heater.

As a preferred embodiment, the second steam extraction port comprises a No. 7 steam extraction port, a No. 8 steam extraction port, a No. 9 steam extraction port and a No. 10 steam extraction port, wherein the No. 7 steam extraction port is communicated with the steam inlet of the No. 9 low-pressure heater, the No. 8 steam extraction port is communicated with the steam inlet of the No. 10 low-pressure heater, the No. 9 steam extraction port is communicated with the steam inlet of the No. 11 low-pressure heater, and the No. 10 steam extraction port is communicated with the steam inlet of the No. 12 low-pressure heater.

The second steam extraction opening is used for sending steam in the low-pressure cylinder of the steam turbine to the low-pressure heater and is used for primarily heating condensed water in the low-pressure heater.

In a preferred embodiment, the first steam outlet of the boiler and the steam inlet of the turbine ultrahigh-pressure cylinder are communicated with each other through a main steam line, the first damper valve and the gulp valve are provided in the main steam line, and the second steam outlet of the boiler and the steam inlet of the turbine high-pressure cylinder are communicated with each other through a reheat steam line.

The main steam pipeline and the reheating steam pipeline are respectively arranged and used for respectively conveying the steam which is heated for the first time to the ultrahigh-pressure cylinder of the steam turbine and conveying the steam which is heated by the primary reheater to the high-pressure cylinder of the steam turbine.

A power regulation method of a double-machine regenerative system is characterized in that an AGC (automatic gain control) or primary frequency modulation load regulation signal is introduced into a control device, and the control device controls a first regulating valve and a second regulating valve according to an AGC or primary frequency modulation load instruction.

As a preferred implementation mode, when an AGC or primary frequency modulation load instruction is reduced, the load instruction is sent to the control device, the control device controls the first regulating valve to be closed to be small, and simultaneously, the second regulating valve is opened to be large, so that steam admission of the regenerative small steam turbine is increased, and the requirement of a power grid is met.

As a preferred embodiment, when the AGC or primary frequency modulation load instruction is increased, the load instruction is sent to the control device, and the control device controls the first regulating valve to be opened largely and simultaneously closes the second regulating valve to reduce the steam admission of the regenerative small steam turbine, thereby meeting the power grid requirement.

After the technical scheme is adopted, the invention has the beneficial effects that:

1. the small regenerative steam turbine coaxially drives the small generator to jointly form a small regenerative steam turbine generator set, the steam turbine ultrahigh pressure cylinder, the steam turbine high pressure cylinder, the steam turbine medium pressure cylinder and the steam turbine low pressure cylinder form a large steam turbine, the large steam turbine and the generator are coaxially connected to jointly form a large steam turbine generator set, and a double-machine regenerative power generation system formed by the large steam turbine generator set and the small steam turbine generator set is realized.

2. Steam in a boiler enters the turbine ultrahigh-pressure cylinder through a steam inlet of the turbine ultrahigh-pressure cylinder to do work, part of the steam exhausted from the turbine ultrahigh-pressure cylinder returns to the boiler again to be heated, part of the steam enters the high-pressure heater to heat feed water, the other part of the steam enters the regenerative small turbine through a steam inlet of the regenerative small turbine to do work, part of the steam exhausted from the regenerative small turbine enters the low-pressure heater to heat condensed water, meanwhile, the steam in the regenerative small turbine enters the high-pressure heater through a first steam extraction port to heat the feed water, the steam reheated by the boiler enters the turbine high-pressure cylinder through a steam inlet of the turbine high-pressure cylinder to do work, and the steam exhausted from the turbine high-pressure cylinder enters the turbine medium-pressure cylinder to do work, and meanwhile, the steam in the low-pressure cylinder of the steam turbine enters a low-pressure heater through a second steam extraction port to heat the condensed water, and the condensed water is heated sequentially by the low-pressure heater, the deaerator and the high-pressure heater and is conveyed to the boiler for cyclic utilization. The invention adopts the regenerative small steam turbine to replace the high-pressure cylinder and the medium-pressure cylinder of the main steam turbine to extract steam respectively, thereby solving the problem of loss caused by the overhigh steam extraction superheat degree.

3. AGC or primary frequency modulation load adjustment signals are introduced into the regenerative small steam turbine control device, the control device controls the second adjusting valve according to AGC or primary frequency modulation load instructions to adjust the steam inlet quantity of the regenerative small steam turbine, the regenerative small steam turbine control device is used for being matched with the load adjustment of a main steam turbine, the AGC adjustment quality and the primary frequency modulation action quality of a unit are improved, the fluctuation of main steam pressure is slowed down, and the control of main steam parameters is facilitated.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of the present invention.

In the figure, 1-boiler; 2-a turbine ultrahigh pressure cylinder; 3-a high-pressure cylinder of the steam turbine; 4-a turbine medium pressure cylinder; 5-low pressure cylinder of steam turbine; 6-a generator; 7-a feed pump; 8-a speed regulating device; 9-a backheating type small steam turbine; 10-small generator; 11-a condenser; a No. 12-1 steam extraction port; no. 13-2 steam extraction port; no. 14-3 steam extraction port; 15-4 steam extraction port 15; a No. 16-5 steam extraction port; no. 17-6 steam extraction port; a number 18-7 steam extraction port; a No. 19-8 steam extraction port; a No. 20-9 steam extraction port; a No. 21-10 steam extraction port; no. 22-1 high pressure heater; no. 23-2 high pressure heater; 24-3 high pressure heater; 25-4 high pressure heater; 26-5 high pressure heater; 27-6 high pressure heater; 29-a deaerator; no. 31-8 low pressure heater; number 32-9 low pressure heater; no. 33-10 low pressure heater; no. 34-11 low pressure heater; number 35-12 low pressure heaters; 36-secondary reheater.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, a dual-machine regenerative system includes a boiler 1, a power generation device, a condenser 11, a regenerative device and a control device, wherein one end of the power generation device is communicated with the boiler 1, the other end of the power generation device is communicated with the condenser 11, one end of the regenerative device is communicated with the condenser 11, and the other end of the regenerative device is communicated with the boiler 1.

The power generation device comprises a main steam turbine power generation unit and a regenerative small steam turbine 9 power generation unit, wherein the main steam turbine power generation unit comprises a steam turbine ultrahigh pressure cylinder 2, a steam turbine high pressure cylinder 3, a steam turbine medium pressure cylinder 4, a steam turbine low pressure cylinder 5, a power generator 6, a steam turbine ultrahigh pressure cylinder 2, steam turbine high pressure cylinder 3, steam turbine middling pressure cylinder 4 and steam turbine low pressure cylinder 5 have constituted the main steam turbine, main steam turbine and generator 6 coaxial coupling constitute big steam turbine generating set jointly, backheating formula little steam turbine 9 generating set includes water feed pump 7, backheating formula little steam turbine 9 and little generator 10, backheating formula little steam turbine 9 one end and water feed pump 7 coaxial coupling, the other end and the little generator 10 coaxial coupling of backheating formula little steam turbine 9, constitute backheating formula little steam turbine 9 generating set jointly, it is provided with speed adjusting device 8 to connect between water feed pump 7 and the little steam turbine 9 of backheating formula.

The regenerative small turbine 9 coaxially drives the small generator 10 to jointly form a regenerative small turbine 9 generator 6 group, the turbine ultrahigh pressure cylinder 2, the turbine high pressure cylinder 3, the turbine medium pressure cylinder 4 and the turbine low pressure cylinder 5 form a large turbine, the large turbine and the generator 6 are coaxially connected to jointly form a large turbine generator 6 group, and a double-machine regenerative power generation system formed by the large turbine generator 6 group and the small turbine generator 6 group is realized.

The regenerative small steam turbine 9 is a regenerative small steam turbine with a constant speed of 3000r/min, the water feeding pump 7 has 100% capacity, the regenerative small steam turbine 9 drives the water feeding pump 7 through the speed regulating device 8, and the small generator 10 is arranged at one end of a steam outlet of the regenerative small steam turbine 9 and used for balancing power, is incorporated into an auxiliary power system and bears part of auxiliary power.

The steam inlet of the turbine ultrahigh-pressure cylinder 2 is communicated with the first steam outlet of the boiler 1, a first adjusting valve and an air compensating valve are arranged between the steam inlet of the turbine ultrahigh-pressure cylinder 2 and the first steam outlet of the boiler 1, the first adjusting valve and the air compensating valve are respectively and electrically connected with the control device, the steam outlet of the turbine ultrahigh-pressure cylinder 2 is respectively communicated with the steam inlet of the boiler 1, the steam inlet of the heat regenerating device and the steam inlet of the small heat regenerating turbine 9, the steam inlet of the turbine high-pressure cylinder 3 is communicated with the second steam outlet of the boiler 1, the steam outlet of the turbine high-pressure cylinder 3 is communicated with the steam inlet of a secondary reheater 36 of the boiler, the steam outlet of the secondary reheater 36 is communicated with the steam inlet of the turbine medium-pressure cylinder, the steam inlet of the turbine low-pressure cylinder 5 is communicated with the steam outlet of the turbine medium-pressure cylinder 4, the steam outlet of the turbine low-pressure cylinder 5 is communicated with the steam inlet of the condenser 11, and a second steam extraction opening is arranged on the low-pressure cylinder 5 of the steam turbine. A second adjusting valve is arranged between the steam inlet of the small regenerative steam turbine 9 and the steam outlet of the ultrahigh pressure cylinder of the steam turbine, the second adjusting valve is electrically connected with the control device, the steam outlet of the small regenerative steam turbine 9 is respectively communicated with the steam inlet of the regenerative device, and a first steam extraction port is arranged on the small regenerative steam turbine 9.

The heat recovery device comprises a high-pressure heater, a deaerator 29 and a low-pressure heater, wherein a water inlet of the low-pressure heater is communicated with a water outlet of the condenser 11, a water outlet of the low-pressure heater is communicated with a water inlet of the deaerator 29, a steam inlet of the low-pressure heater is communicated with a second steam extraction port, a water inlet of the high-pressure heater is communicated with a water outlet of the deaerator 29, a water outlet of the high-pressure heater is communicated with a water inlet of the boiler 1, and a steam inlet of the high-pressure heater and a steam inlet of the deaerator 29 are respectively communicated with a first steam.

Steam in the boiler 1 enters the turbine ultrahigh-pressure cylinder 2 through a steam inlet of the turbine ultrahigh-pressure cylinder 2 to do work, part of the steam exhausted from the turbine ultrahigh-pressure cylinder 2 returns to the boiler 1 again to be reheated, part of the steam enters the high-pressure heater to heat feed water, the other part of the steam enters the regenerative small turbine 9 through a steam inlet of the regenerative small turbine 9 to do work, the steam exhausted from the regenerative small turbine 9 enters the low-pressure heater under normal conditions to heat condensed water, meanwhile, the steam in the regenerative small turbine 9 enters the high-pressure heater through a first steam extraction port to heat the feed water, the steam reheated by the boiler 1 enters the turbine high-pressure cylinder 3 through a steam inlet of the turbine high-pressure cylinder 3 to do work, and the steam exhausted from the turbine high-pressure cylinder 3 enters a secondary reheater 36 of the boiler to be heated, then the steam enters a steam turbine medium-pressure cylinder 4 to do work, the steam discharged from the steam turbine medium-pressure cylinder 4 enters a steam turbine low-pressure cylinder 5 to do work, the steam discharged from the steam turbine low-pressure cylinder 5 enters a condenser 11 to be condensed into condensed water, meanwhile, the steam in the steam turbine low-pressure cylinder 5 enters a low-pressure heater through a second steam extraction port to heat the condensed water, and the condensed water is heated sequentially through a low-pressure heater, a deaerator 29 and a high-pressure heater and conveyed to the boiler 1 to be recycled. The problem of excessive extraction superheat is caused by the fact that extraction is usually carried out from a high-pressure cylinder 2 and a medium-pressure cylinder 4 of a steam turbine in the prior art. The extraction steam of the backheating type small steam turbine 9 is not reheated, has lower temperature, is used for replacing the extraction steam of the high-pressure cylinder 3 and the medium-pressure cylinder 4 of the main steam turbine to be greatly reduced, and can reduce the irreversible loss of heat transfer. The steam turbine medium pressure cylinder 4 is in a symmetrical split flow type, two steam outlets are arranged on two sides of the steam turbine medium pressure cylinder 4, and the two steam outlets are communicated with a steam inlet of the steam turbine low pressure cylinder 5 after being converged. The steam turbine low-pressure cylinder 5 is in a symmetrical split-flow type, and both sides of the steam turbine low-pressure cylinder 5 are respectively provided with a steam outlet which is communicated with a steam inlet of the condenser 11. A secondary reheater 36 of the boiler is arranged between the steam inlet of the turbine intermediate-pressure cylinder 4 and the steam outlet of the turbine high-pressure cylinder 3, and is used for reheating the steam coming out of the turbine high-pressure cylinder 3.

The reason that the symmetrical split flow type is adopted by the turbine medium pressure cylinder 4 is that the steam flow passing through each stage of blades of the turbine medium pressure cylinder 4 is increased along with the increase of the capacity of the unit, so that the length of the blades is increased to ensure the passing of the steam flow. However, the blades are too long and are limited by the strength of materials under the high-speed rotation of the steam turbine, and the blade fracture accident is easy to happen, so that the medium-pressure cylinder 4 of the high-capacity unit steam turbine adopts a symmetrical split flow type, the lengths of all stages of blades of the medium-pressure cylinder 4 of the steam turbine are shortened, the output of the unit is ensured, and in addition, the axial thrust can be reduced. The reason that the symmetrical split flow type is adopted for the low-pressure cylinder 5 of the steam turbine is that the steam flow passing through each stage of blades of the low-pressure cylinder 5 of the steam turbine is increased after the capacity of the unit is increased, so that the length of the blades is increased to ensure the steam flow to pass through. However, the blades are too long and are limited by the strength of materials under the high-speed rotation of the steam turbine, and the blade fracture accident is easy to happen, so that the low-pressure cylinder 5 of the high-capacity unit steam turbine adopts a symmetrical split flow type, the lengths of all stages of blades of the low-pressure cylinder 5 of the steam turbine are shortened, the output of the unit is ensured, and in addition, the axial thrust can be reduced.

The high-pressure heater comprises a No. 1 high-pressure heater 22, a No. 2 high-pressure heater 23, a No. 3 high-pressure heater 24, a No. 4 high-pressure heater 25, a No. 5 high-pressure heater 26 and a No. 6 high-pressure heater 27 in sequence, wherein the water outlet of the No. 1 high-pressure heater 22 is communicated with the water inlet of the boiler 1, the steam inlet of the No. 1 high-pressure heater 22 is communicated with the steam outlet of the turbine ultrahigh-pressure cylinder 2, the water inlet of the No. 6 high-pressure heater 27 is communicated with the water outlet of the deaerator 29, the steam pressures in the No. 2 high-pressure heaters 23 to 6 high-pressure heaters 27 are arranged from high to low, the low-pressure heaters comprise a No. 8 low-pressure heater 31, a No. 9 low-pressure heater 32, a No. 10 low-pressure heater 33, a No., the steam inlet of the No. 8 low-pressure heater 31 is communicated with the steam outlet of the backheating type small steam turbine 9, the steam inlet of the No. 9 low-pressure heater 32 is communicated with the steam outlet of the backheating type small steam turbine 9 and the second steam extraction port of the main steam turbine low-pressure cylinder, the water inlet of the No. 12 low-pressure heater 35 is communicated with the condensed water device, and the steam pressure in the No. 9 low-pressure heaters 32-No. 12 low-pressure heaters 35 is arranged from high to low.

The condensed water condensed by the condenser 11 enters the No. 12 low-pressure heater 35, the low-pressure heater heats the condensed water, the heated condensed water enters the deaerator 29 through the No. 8 low-pressure heater 31, the deaerator 29 is used for removing oxygen and other gases of the condensed water, the condensed water in the deaerator 29 is pumped into the high-pressure heater by the water feed pump 7, and the condensed water after being heated by the high-pressure heater enters the boiler 1 through the No. 1 high-pressure heater 22.

The first steam extraction port comprises a No. 1 steam extraction port 12, a No. 2 steam extraction port 13, a No. 3 steam extraction port 14, a No. 4 steam extraction port 15, a No. 5 steam extraction port 16 and a No. 6 steam extraction port 17, wherein the No. 1 steam extraction port 12 is communicated with a steam inlet of a No. 2 high-pressure heater 23, the No. 2 steam extraction port 13 is communicated with a steam inlet of a No. 3 high-pressure heater 24, the No. 3 steam extraction port 14 is communicated with a steam inlet of a No. 4 high-pressure heater 25, the No. 4 steam extraction port 15 is communicated with a steam inlet of a No. 5 high-pressure heater 26, the No. 5 steam extraction port 16 is communicated with a steam inlet of a No. 6 high-pressure heater 27, and the No. 6 steam extraction port 17 is communicated with a steam inlet of a deaerator 29.

The first extraction port is used to feed steam from the regenerative steam turbine 9 to the high pressure heater and deaerator 29 for further heating the feed water in the high pressure heater.

The second steam extraction port comprises a No. 7 steam extraction port 18, a No. 8 steam extraction port 19, a No. 9 steam extraction port 20 and a No. 10 steam extraction port 21, wherein the No. 7 steam extraction port 18 is communicated with a steam inlet of a No. 9 low-pressure heater 32, the No. 8 steam extraction port 19 is communicated with a steam inlet of a No. 10 low-pressure heater 33, the No. 9 steam extraction port 20 is communicated with a steam inlet of a No. 11 low-pressure heater 34, and the No. 10 steam extraction port 21 is communicated with a steam inlet of a No. 12 low-pressure heater 35.

The second extraction opening is used for sending steam in the low-pressure cylinder 5 of the steam turbine to the low-pressure heater and is used for primarily heating condensed water in the low-pressure heater.

Between the first steam outlet of boiler 1 and the steam inlet of steam turbine super high pressure cylinder 2, communicate through main steam pipeline, first accent valve and gulp valve set up on main steam pipeline, between the second steam outlet of boiler 1 and the steam inlet of steam turbine high pressure cylinder 3, communicate through reheat steam pipeline.

The main steam pipeline, the primary reheating steam pipeline and the secondary reheating pipeline are respectively arranged and used for respectively conveying the firstly heated steam to the turbine ultrahigh-pressure cylinder 2, conveying the firstly reheated steam to the turbine high-pressure cylinder 3 and conveying the secondly reheated steam to the medium-pressure cylinder 4.

A power regulation method of a double-machine regenerative system is characterized in that an AGC (automatic gain control) or primary frequency modulation load regulation signal is introduced into a control device, the control device controls a second regulating valve according to an AGC or primary frequency modulation load instruction, and the steam inlet quantity of a regenerative small steam turbine 9 is regulated and is used for being matched with load regulation of a main steam turbine to improve AGC regulation quality and unit primary frequency modulation action quality.

When the main steam turbine generator 6 set and the regenerative small steam turbine 9 generator 6 set operate normally, the second regulating valve does not participate in regulation, and the rotating speed of the water feeding pump 7 is regulated through the speed regulating device 8 to meet the requirement of the boiler 1. The surplus power of the backheating type small turbine 9 passes through the power balance small generator 10, and the part of the power is used for service.

When an AGC (automatic gain control) or primary frequency modulation load instruction is increased, the control device controls the main steam turbine to open the first modulating valve and the steam supplementing valve, meanwhile, the load instruction is sent to the control device, the second modulating valve is closed, the steam admission of the regenerative small steam turbine 9 is reduced, the output of the main steam turbine is improved, and the power grid requirement is met.

When the AGC or primary frequency modulation load instruction is reduced, the control device controls the main steam turbine to close the first modulating valve and send the load instruction to the control device, and opens the second modulating valve, so that the steam admission of the regenerative small steam turbine 9 is increased, the output of the main steam turbine is reduced, and the power grid requirement is met. When the double-machine regenerative system operates normally, in order to improve the load reduction speed of the main turbine, the second regulating valve of the regenerative small turbine 9 can be kept in an incomplete opening state when the double-machine regenerative system operates normally.

The load regulation control mode not only can quickly regulate the load of the main steam turbine, improve the AGC regulation quality, the primary frequency regulation action qualification rate and improve the economic benefit of a power plant, but also can slow down the main steam pressure fluctuation and the temperature fluctuation caused by the load fluctuation of the main steam turbine and is beneficial to parameter control because the action direction of the second regulating valve of the regenerative small steam turbine 9 is opposite to the action direction of the first regulating valve and the gulp valve of the main steam turbine.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.