阅读说明：本技术 一种高效低温低压蒸汽余热利用联合发电系统及其控制方法 (Efficient low-temperature low-pressure steam waste heat utilization combined power generation system and control method thereof ) 是由 邓浩 郭擎 李鹏春 张建云 谢小华 周东 文鑫 吴小荣 刁钟洋 陈华露 于 2021-10-08 设计创作，主要内容包括：本发明涉及蒸汽机装置领域,具体涉及一种高效低温低压蒸汽余热利用联合发电系统及其控制方法,包括余热蒸气通入汽轮机中驱动双伸轴发电机发电；汽轮机排出的蒸气进入蒸发器中加热工质；工质膨胀驱动双伸轴发电机发电；工质冷却后循环流回蒸发器中；提升双伸轴发电机转速至额定转速；双伸轴发电机并网柜合闸；提升双伸轴发电机的输出功率至额定功率运行。从而可以分级对余热中的能量进行使用,提高工作效率。(The invention relates to the field of steam engine devices, in particular to a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system and a control method thereof, wherein waste heat steam is introduced into a steam turbine to drive a double-extension-shaft generator to generate power; steam exhausted by the steam turbine enters an evaporator to heat a working medium; the working medium expands to drive the double-extension-shaft generator to generate electricity; after being cooled, the working medium circularly flows back to the evaporator; the rotating speed of the double-extension-shaft generator is increased to a rated rotating speed; closing the grid-connected cabinet of the double-extension-shaft generator; and the output power of the double-extension-shaft generator is improved to the rated power for operation. Therefore, the energy in the waste heat can be used in a grading manner, and the working efficiency is improved.)

1. A high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system which is characterized in that,

the double-extension-shaft generator comprises a steam turbine, an evaporator, an organic working medium turbine, a double-extension-shaft generator and a working medium circulating mechanism, wherein the evaporator is connected with the steam turbine, the organic working medium turbine is connected with the evaporator, two ends of the double-extension-shaft generator are respectively connected with the steam turbine and the organic working medium turbine, and the working medium circulating mechanism is arranged between the organic working medium turbine and the evaporator.

2. The high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system of claim 1,

the double-extension-shaft generator comprises a motor body, a steam speed reducer and a working medium speed reducer, wherein two ends of the motor body are respectively connected with the steam speed reducer and the working medium speed reducer, the steam speed reducer is connected with the steam turbine, and the working medium speed reducer is connected with the organic working medium turbine.

3. The high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system of claim 1,

the double-extension-shaft generator comprises a motor body, a steam speed reducer, a working medium speed reducer and an overrunning clutch, wherein two ends of the motor body are respectively connected with the steam speed reducer and the working medium speed reducer, the steam speed reducer is connected with the steam turbine, the overrunning clutch is connected with the working medium speed reducer, and the organic working medium turbine is connected with the overrunning clutch.

4. The high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system of claim 1,

the working medium circulating mechanism comprises a condenser and a circulating pump, the condenser is connected with the organic working medium turbine, one end of the circulating pump is connected with the condenser, and the other end of the circulating pump is connected with the evaporator.

5. The high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system of claim 1,

the evaporator comprises an evaporator body, a working medium inlet valve and a working medium bypass valve, the working medium inlet valve is communicated with the working medium bypass valve and communicated with the evaporator body, the organic working medium turbine is connected with the working medium inlet valve, and the working medium circulating mechanism is connected with the working medium bypass valve.

6. The high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system of claim 1,

the steam turbine comprises a steam turbine body, a steam inlet valve and a steam bypass valve, wherein the steam inlet valve is communicated with the steam bypass valve and is communicated with the steam turbine body.

7. A control method of the high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system is applied to the high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system as claimed in claim 1,

the method comprises the following steps:

introducing waste heat steam into a steam turbine to drive a double-extension-shaft generator to generate electricity;

steam exhausted by the steam turbine enters an evaporator to heat a working medium;

the working medium expands to drive the double-extension-shaft generator to generate electricity;

after being cooled, the working medium circularly flows back to the evaporator;

the rotating speed of the double-extension-shaft generator is increased to a rated rotating speed;

closing the grid-connected cabinet of the double-extension-shaft generator;

and the output power of the double-extension-shaft generator is improved to the rated power for operation.

Technical Field

The invention relates to the field of steam engine devices, in particular to a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system and a control method thereof.

Background

The industrial energy consumption of China accounts for about 70% of the total energy consumption, and 60% -65% of the industrial energy consumption is converted into waste heat with different carriers and different temperatures. The method has the advantages that a large number of low-temperature waste heat steam resources exist in the industries of steel, glass, chemical industry and the like, various low-temperature waste heat steam resources in the industrial production process are recycled, the energy problem of China is solved, the environmental pollution in the industrial production process can be effectively reduced, and the method has very important practical significance.

The condensing steam turbine system is a common means for recovering low-temperature waste heat steam energy, but when a traditional condensing steam turbine system is adopted to recover waste heat from low superheat degree or saturated low-temperature waste heat steam resources with small flow, the steam turbine system cannot realize efficient operation and cannot fully recover and utilize the low-temperature waste heat steam energy due to the limitation of technical conditions such as the characteristics of steam (shown in fig. 1, the steam turbine system belongs to wet fluid), the height of a steam turbine blade, the partial steam admission degree and the steam exhaust water content.

Disclosure of Invention

The invention aims to provide an efficient low-temperature low-pressure steam waste heat utilization combined power generation system and a control method thereof, and aims to improve the efficiency of waste heat power generation.

In order to achieve the purpose, the invention provides a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system and a control method thereof.

The double-extension-shaft generator comprises a motor body, a steam speed reducer and a working medium speed reducer, wherein two ends of the motor body are respectively connected with the steam speed reducer and the working medium speed reducer, the steam speed reducer is connected with the steam turbine, and the working medium speed reducer is connected with the organic working medium turbine.

The double-extension-shaft generator comprises a motor body, a steam speed reducer, a working medium speed reducer and an overrunning clutch, wherein two ends of the motor body are respectively connected with the steam speed reducer and the working medium speed reducer, the steam speed reducer is connected with the steam turbine, the overrunning clutch is connected with the working medium speed reducer, and the organic working medium turbine is connected with the overrunning clutch.

The working medium circulating mechanism comprises a condenser and a circulating pump, the condenser is connected with the organic working medium turbine, one end of the circulating pump is connected with the condenser, and the other end of the circulating pump is connected with the evaporator.

The evaporator comprises an evaporator body, a working medium inlet valve and a working medium bypass valve, wherein the working medium inlet valve is communicated with the working medium bypass valve and is communicated with the evaporator body.

The evaporator comprises an evaporator body, a working medium inlet valve and a working medium bypass valve, the working medium inlet valve is communicated with the working medium bypass valve and communicated with the evaporator body, the organic working medium turbine is connected with the working medium inlet valve, and the working medium circulating mechanism is connected with the working medium bypass valve.

In a second aspect, the present invention further provides a control method for a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system, including: introducing waste heat steam into a steam turbine to drive a double-extension-shaft generator to generate electricity; steam exhausted by the steam turbine enters an evaporator to heat a working medium; the working medium expands to drive the double-extension-shaft generator to generate electricity; after being cooled, the working medium circularly flows back to the evaporator; the rotating speed of the double-extension-shaft generator is increased to a rated rotating speed; closing the grid-connected cabinet of the double-extension-shaft generator; and the output power of the double-extension-shaft generator is improved to the rated power for operation.

The invention relates to a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system and a control method thereof. The work done by the steam turbine and the organic working medium expander is output through the double-extension-shaft generator, the cascade utilization of the energy of the waste heat steam is realized, and the utilization rate of the energy is improved. The conventional steam turbine pursues efficiency, and the exhaust pressure is lower, so that the water content is higher, and the service life of a blade is short. The invention adopts the back pressure type design, so the water content of the exhaust gas is low, the design difficulty of the steam turbine is reduced, the service life of the blade is prolonged, and the service life of the system is further ensured.

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, 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 the drawings without creative efforts.

FIG. 1 is a water vapor temperature entropy diagram;

FIG. 2 is a schematic temperature entropy diagram of the steam turbine-ORC system of the present invention;

FIG. 3 is a graph of steam turbine flow rate versus speed according to the present invention;

FIG. 4 is a graph of the flow rate and rotational speed of the organic working medium turbine of the present invention;

FIG. 5 is a structural view of embodiment 1 of the present invention;

FIG. 6 is a structural view of embodiment 2 of the present invention;

FIG. 7 is a structural view of embodiment 3 of the present invention;

fig. 8 is a flowchart of embodiment 4 of the present invention.

The system comprises a steam turbine 1, a steam turbine 2, an evaporator 3, an organic working medium turbine 4, a double-extension-shaft generator 5, a working medium circulating mechanism 11, a steam turbine body 12, a steam inlet valve 13, a steam bypass valve 21, an evaporator body 22, a working medium inlet valve 23, a working medium bypass valve 41, a motor body 42, a steam reducer 43, a working medium reducer 44, an overrunning clutch 51, a condenser and a circulating pump 52.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Example 1

Referring to fig. 5, the present invention provides a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system, including:

the system comprises a steam turbine 1, an evaporator 2, an organic working medium turbine 3, a double-extension-shaft generator 4 and a working medium circulating mechanism 5, wherein the evaporator 2 is connected with the steam turbine 1, the organic working medium turbine 3 is connected with the evaporator 2, two ends of the double-extension-shaft generator 4 are respectively connected with the steam turbine 1 and the organic working medium turbine 3, and the working medium circulating mechanism 5 is arranged between the organic working medium turbine 3 and the evaporator 2.

In the present embodiment, the exhaust heat steam drives the steam turbine 1 to rotate; waste heat steam dead steam from the tail part of the steam turbine 1 exchanges heat with the liquid organic working medium, so that the working medium becomes a high-temperature high-pressure overheated organic working medium; the high-temperature high-pressure overheated organic working medium expands and does work in the organic working medium turbine 3 to drive the double-extension-shaft generator 4 to rotate; then the working medium circulating mechanism 5 condenses the low-temperature low-pressure organic working medium exhaust steam discharged after the organic working medium turbine 3 does work into a low-temperature low-pressure liquid saturated organic working medium, and pressurizes the low-temperature low-pressure liquid organic working medium discharged from the condenser 51 so as to enable the low-temperature low-pressure liquid organic working medium to enter the evaporator 2 for the next circulation.

When the temperature and pressure of the steam waste heat are T1 and P1, and the temperature and pressure of the exhaust steam after the system does work are T3 and P3, if only the traditional condensing steam system is adopted, the steam turbine efficiency is low because the steam is low-temperature low-pressure saturated steam or the superheat degree is low, and the turbine outlet point must enter a latent heat zone, namely the final stage of the steam turbine 1 must contain water. Aiming at the phenomenon, the invention provides the graded utilization of energy, namely high-grade energy in a heat source supplied to a power generation system is supplied to a steam turbine 1 to do work, and low-grade energy is supplied to an organic working medium turbine 3 to do work. As shown in fig. 2, the temperature and pressure of the steam at the inlet of the steam turbine 1 are T1 and P1, and the temperature and pressure of the steam at the outlet are T2 and P2, at this time, the outlet of the steam turbine 1 is gas, the water content is extremely low, and the efficiency of the steam turbine 1 is high. And then, taking the outlet steam of the steam turbine 1 as a heat source of an ORC system, introducing the heat source into the evaporator 2 to exchange heat with the organic working medium, heating the organic working medium to the superheated organic working medium with the temperature and the pressure of T2 'and P2', and expanding the superheated organic working medium to work to the low-temperature and low-pressure organic working medium of T3 and P3 through the organic working medium turbine 3.

Through analysis, compared with a method for realizing waste heat recovery and utilization of low-temperature and low-pressure steam through a steam turbine 1-ORC combined power generation system, energy loss generated when steam and an organic working medium exchange heat in an evaporator 2 exists in the middle of the steam turbine 1 system, but comprehensive calculation finds that the total efficiency of the system is improved by 15% -20% compared with that of the steam turbine 1 system.

Example 2

Referring to fig. 6, the present invention provides a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system, including:

the system comprises a steam turbine 1, an evaporator 2, an organic working medium turbine 3, a double-extension-shaft generator 4 and a working medium circulating mechanism 5, wherein the evaporator 2 is connected with the steam turbine 1, the organic working medium turbine 3 is connected with the evaporator 2, two ends of the double-extension-shaft generator 4 are respectively connected with the steam turbine 1 and the organic working medium turbine 3, and the working medium circulating mechanism 5 is arranged between the organic working medium turbine 3 and the evaporator 2.

The double-extension-shaft generator 4 comprises a motor body 41, a steam speed reducer 42 and a working medium speed reducer 43, wherein two ends of the motor body 41 are respectively connected with the steam speed reducer and the working medium speed reducer 43, the steam speed reducer is connected with the steam turbine 1, and the working medium speed reducer 43 is connected with the organic working medium turbine 3.

The working medium circulating mechanism 5 comprises a condenser 51 and a circulating pump 52, the condenser 51 is connected with the organic working medium turbine 3, one end of the circulating pump 52 is connected with the condenser 51, and the other end of the circulating pump 52 is connected with the evaporator 2.

The evaporator 2 comprises an evaporator body 21, a working medium inlet valve 22 and a working medium bypass valve 23, the working medium inlet valve 22 is communicated with the working medium bypass valve 23 and is communicated with the evaporator body 21, the organic working medium turbine 3 is connected with the working medium inlet valve 22, and the working medium circulating mechanism 5 is connected with the working medium bypass valve 23.

The steam turbine 1 includes a turbine body 11, a steam inlet valve 12, and a steam bypass valve 13, and the steam inlet valve 12 and the steam bypass valve 13 are communicated with each other and with the turbine body 11.

In the present embodiment, steam enters from the steam inlet valve 12 and the steam bypass valve 13 to drive the steam turbine body 11 to rotate, and the steam speed reducer can reduce the speed to improve safety; the evaporator 2 exchanges heat with the liquid organic working medium by utilizing waste heat steam dead steam from the tail part of the steam turbine 1 to make the working medium become a high-temperature high-pressure overheat organic working medium; the high-temperature high-pressure overheated organic working medium expands in the organic working medium turbine 3 through the working medium inlet valve 22 and the working medium bypass valve 23 to do work, drives the generator to rotate, and improves the safety through the working medium speed reducer 43; then the condenser 51 condenses the low-temperature low-pressure organic working medium exhaust steam discharged after the organic working medium turbine 3 does work into a low-temperature low-pressure liquid saturated organic working medium, and the circulating pump 52 pressurizes the low-temperature low-pressure liquid organic working medium discharged from the condenser 51 and makes the low-temperature low-pressure liquid organic working medium enter the evaporator 2 for the next circulation.

The steam inlet valve has the functions of adjusting and quickly closing, and the rotating speed of the steam turbine 1 is controlled by adjusting the steam inlet valve

The working medium inlet valve 22 has the functions of adjusting and quickly closing, and realizes the control of the rotating speed of the organic working medium turbine 3.

When the waste heat combined generator set has an emergency, the steam bypass valve and the working medium bypass valve 23 are opened simultaneously, and the steam inlet valve and the working medium inlet valve 22 are closed simultaneously, so that the emergency stop of the generator set is realized.

When the system operates under variable working conditions, the system does not have the overrunning clutch 44, and if only the steam inlet valve is adjusted, the system is difficult to maintain stable, so when the system operates under variable working conditions, the flow and rotating speed curves (as shown in fig. 3 and 4) of the steam turbine 1 and the organic working medium turbine 3 are obtained through simulation calculation according to the flow power characteristic curves of the steam turbine 1 and the organic working medium turbine 3, and further the valve opening ratio of the steam inlet valve and the working medium inlet valve 22 is obtained. And then the steam inlet valve and the working medium inlet valve 22 are simultaneously adjusted according to the proportion, so that the system can rapidly achieve stable operation.

The generator is connected to the power grid, the generator is an asynchronous generator, after the rotating speed of the generator is dragged to the rated rotating speed, the grid cabinet breaker is combined, the terminal voltage and the frequency of the generator are kept consistent with those of the power grid after the generator is switched on, the rotating speed of the generator is increased, the rotating speed of a rotor of the generator exceeds the synchronous rotating speed, and the generator outputs electric energy to the power grid. By increasing the air input of the turbine, the output power of the generator is improved.

The steam turbine adopts the suspension type structure, and the steam turbine directly hangs in the high-speed axle head of reduction gears promptly, can reduce the mechanical loss of unit, improves unit efficiency. Meanwhile, when the flow of the waste heat steam is small, the limitation of the traditional steam turbine by the rotating speed is avoided, the rotating speed of the steam turbine can be increased, and the efficiency of the steam turbine can be improved.

The organic working medium turbine can select the type of the organic working medium, the turbine type of the organic working medium expander and the like according to the exhaust steam state discharged by the steam turbine, and whether an organic working medium turbine reduction gear mechanism is used or not, so that the compatibility is extremely high.

The steam turbine, the organic working medium turbine, the steam turbine speed reducing mechanism, the organic working medium turbine speed reducing mechanism and the double-extension-shaft generator jointly form a waste heat utilization combined generator set. Mechanical loss of the system in the process of converting heat energy into electric energy is reduced, and system efficiency is improved. Meanwhile, the generator set adopts an integrated skid-mounted structure, and is small in size and convenient to install and transport.

Example 3

Referring to fig. 7, the present invention provides a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system, including:

the system comprises a steam turbine 1, an evaporator 2, an organic working medium turbine 3, a double-extension-shaft generator 4 and a working medium circulating mechanism 5, wherein the evaporator 2 is connected with the steam turbine 1, the organic working medium turbine 3 is connected with the evaporator 2, two ends of the double-extension-shaft generator 4 are respectively connected with the steam turbine 1 and the organic working medium turbine 3, and the working medium circulating mechanism 5 is arranged between the organic working medium turbine 3 and the evaporator 2.

The double-extension-shaft generator 4 comprises a motor body 41, a steam reducer 42, a working medium reducer 43 and an overrunning clutch 44, wherein two ends of the motor body 41 are respectively connected with the steam reducer and the working medium reducer 43, the steam reducer is connected with the steam turbine 1, the overrunning clutch 44 is connected with the working medium reducer 43, and the organic working medium turbine 3 is connected with the overrunning clutch 44.

The working medium circulating mechanism 5 comprises a condenser 51 and a circulating pump 52, the condenser 51 is connected with the organic working medium turbine 3, one end of the circulating pump 52 is connected with the condenser 51, and the other end of the circulating pump 52 is connected with the evaporator 2.

The evaporator 2 comprises an evaporator body 21, a working medium inlet valve 22 and a working medium bypass valve 23, wherein the working medium inlet valve 22 is communicated with the working medium bypass valve 23 and is communicated with the evaporator body 21.

The steam turbine 1 includes a turbine body 11, a steam inlet valve 12, and a steam bypass valve 13, and the steam inlet valve 12 and the steam bypass valve 13 are communicated with each other and with the turbine body 11.

The difference between this embodiment and embodiment 2 is the overrunning clutch 44, and therefore the overrunning clutch 44 will be mainly described in detail. After steam dead steam from the steam turbine 1 enters the evaporator 2, heating and generating organic working medium steam, realizing the control of the rotating speed of the organic working medium turbine 2 by adjusting the working medium inlet valve 22, reducing the speed of the organic working medium turbine 3 by the working medium speed reducer 43, and automatically engaging the overrunning clutch 44 with the double-extension-shaft generator 4 when the rotating speed reaches the rated rotating speed. Therefore, the system can quickly reach a stable operation state.

Example 4

Referring to fig. 8, the present invention provides a control method for a high-efficiency low-temperature low-pressure steam waste heat utilization combined power generation system, which is characterized by comprising:

s101, introducing waste heat steam into a steam turbine 1 to drive a double-extension-shaft generator 4 to generate electricity;

the waste heat steam drives the steam turbine 1 to rotate and drive the double-extension-shaft generator 4 to generate electricity.

S102, steam exhausted by the steam turbine 1 enters an evaporator 2 to heat working medium;

waste heat steam dead steam from the tail part of the steam turbine 1 exchanges heat with the liquid organic working medium, so that the working medium becomes the high-temperature high-pressure overheated organic working medium.

S103, expanding the working medium to drive the double-extension-shaft generator 4 to generate electricity;

the high-temperature high-pressure overheated organic working medium expands and acts in the organic working medium turbine 3 to drive the double-extension-shaft generator 4 to rotate

S104, cooling the working medium, and then circularly flowing back to the evaporator 2;

then the working medium circulating mechanism 5 condenses the low-temperature low-pressure organic working medium exhaust steam discharged after the organic working medium turbine 3 does work into a low-temperature low-pressure liquid saturated organic working medium, and pressurizes the low-temperature low-pressure liquid organic working medium discharged from the condenser 51 so as to enable the low-temperature low-pressure liquid organic working medium to enter the evaporator 2 for the next circulation.

S105, increasing the rotating speed of the double-extension-shaft generator to a rated rotating speed;

s106, closing the grid-connected cabinet of the double-extension-shaft generator;

s107, the output power of the double-extension-shaft generator is increased to the rated power for operation.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.