1. A low-pressure cylinder cutting heat supply unit low-pressure heating and back-heating system is characterized by comprising a medium-pressure cylinder, a low-pressure cylinder communicated with the medium-pressure cylinder through a communicating pipe, a low-pressure heating system connected with the medium-pressure cylinder, a drainage system connected with the low-pressure heating system, and a deaerator connected with the medium-pressure cylinder; and the input end of the deaerator is connected with the low pressure feeding system.

2. The low-pressure cylinder cutting cylinder heat supply unit low-heating reheating system of claim 1, wherein the low-heating reheating system comprises a low heating unit and a fourth heating unit, a low heating unit and a third heating unit, a low heating unit and a second heating unit, and a low heating unit and a first heating unit which are sequentially connected with a deaerator;

the low pressure cylinder and the high pressure cylinder are connected with a medium pressure cylinder or a low pressure cylinder; the low pressure cylinder is connected with the low pressure cylinder;

the hydrophobic system is connected with the lower heater.

3. The low-pressure cylinder cutting cylinder heat supply unit low-heating and back-heating system according to claim 2, wherein a fourth low-heating and draining pipeline is further arranged between the fourth low-heating and the third low-heating, a third low-heating and draining pipeline is further arranged between the third low-heating and the second low-heating, and a second low-heating and draining pipeline is further arranged between the second low-heating and the first low-heating; the condenser is connected with the lower-plus-one part; a first low pressure drainage pipeline is arranged between the first low pressure drainage pipeline and the condenser;

a hydrophobic isolation valve is arranged on the third low-pressure drainage pipeline; and the third low plus hydrophobic pipeline is connected with a hydrophobic system.

4. The low-pressure cylinder cutting cylinder heating unit low-heating-return system as claimed in claim 3, wherein the intermediate pressure cylinder is provided with a heating steam extraction pipeline, and the low-heating tee is connected with the heating steam extraction pipeline through the heating steam extraction and return pipeline; the heat supply steam extraction heat return pipeline is sequentially provided with a heat supply steam extraction heat return check valve, a heat supply steam extraction heat return regulating valve and a heat supply steam extraction heat return shutoff valve; the heat supply steam extraction regenerative shutoff valve is arranged between the low heating valve III and the heat supply steam extraction regenerative regulating valve.

5. The low-pressure cylinder cutting cylinder heating unit low-heating reheating system according to claim 4, wherein the low-heating unit III is connected with the low-pressure cylinder through a third low-heating steam extraction pipeline; the third low pressure steam extraction pipeline is sequentially provided with a steam extraction check valve and a steam extraction shutoff valve; the steam extraction shutoff valve is positioned between the steam extraction check valve and the lower valve.

6. The low-pressure cylinder-switching heating unit low-heating back-heating system as claimed in claim 5, further comprising a bypass outlet shutoff valve between the low-heating three and the low-heating two, and a bypass inlet shutoff valve at the input end of the low-heating one.

7. The low-pressure cylinder cutting cylinder heating unit low-heating reheating system according to claim 6, wherein the low-heating system further comprises a bypass pipeline, a bypass valve installed on the bypass pipeline; one end of the bypass pipeline is connected with a pipeline between the low-plus-three valve and the bypass outlet shutoff valve, and the other end of the bypass pipeline is connected with the input end of the bypass inlet shutoff valve.

8. The low-pressure cylinder-cutting heating unit low-heating-rate reheating system according to claim 7, wherein an input end of the bypass inlet shutoff valve is connected with a condensed water pipeline.

9. The low-pressure cylinder cutting cylinder heat supply unit low-heating and back-heating system according to any one of claims 3 to 8, wherein the drainage system comprises a drainage and expansion pipeline connected with a third low-heating and drainage pipeline, a drainage regulating valve installed on the drainage and expansion pipeline, and a drainage flash tank connected with the output end of the drainage and expansion pipeline.

10. The low-pressure cylinder cutting cylinder heating unit low-heating reheating system according to claim 9, wherein a heating butterfly valve is installed on the communicating pipe.

Background

According to the conventional thermal power generating unit, after the low-pressure cylinder is switched to supply heat, the low-pressure cylinder is cut off, the steam extraction and heat return part of the low-pressure cylinder is correspondingly cut off, and meanwhile, in order to reduce the blast loss of the low-pressure last-stage blade, the low-pressure cylinder exhausts steam to maintain low back pressure.

In operation, because the low-pressure cylinder operates at low back pressure, and the water supplement for heat supply and steam extraction is supplemented to the condenser, because the steam exhaust amount of the steam turbine is very small, the newly supplemented chemical water cannot be regenerated sufficiently, and the condensed water in the condenser has the characteristics of low water temperature, high supercooling degree and high oxygen content; during the operation of the regenerative system, because of the working condition of cylinder cutting, there is no regenerative heat of the steam extraction of the low pressure cylinder part, the temperature of the condensed water is low when the condensed water enters the heater of the steam extraction section of the medium pressure cylinder, the heat load of the heater is large, which causes the large steam extraction amount of the low pressure heater of the stage and the high flow rate of the pipeline, and simultaneously, because the required heat load is large, the area of the original heater is seriously insufficient, which causes the large difference of the outlet end of the heater; the heat exchange effect of the next-stage hybrid heater (deaerator) is influenced, the outlet temperature of the deaerator is low, and the deaerator cannot deaerate thoroughly due to the fact that the supercooling degree of condensed water in the deaerator is large, and the oxygen content of the condensed water is high; the oxygen content of the condensed water is high, so that the heat transfer of the subsequent surface heat exchanger is deteriorated, and the heat economy of the unit is reduced; it also causes corrosion of the thermal power equipment and its pipes, where the dissolved carbon dioxide also increases the oxygen corrosion

Disclosure of Invention

The invention aims to solve the technical problem of providing a low-heating and back-heating system of a low-pressure cylinder cutting heat supply unit; the water temperature at the inlet of the deaerator is increased, the deaerator is operated according to the capacity of the original deaerator, and the deaerator capacity is ensured; the steam extraction quantity of a deaerator stage (high energy level) can be correspondingly reduced, the steam extraction quantity of the medium pressure cylinder exhaust steam (low energy level) is mostly utilized, and the running economy of the unit is improved.

The technical problem to be solved by the invention is as follows:

a low-pressure cylinder cutting heat supply unit low-pressure heating and back-heating system comprises a medium-pressure cylinder, a low-pressure cylinder communicated with the medium-pressure cylinder through a communicating pipe, a low-pressure heating system connected with the medium-pressure cylinder, a drainage system connected with the low-pressure heating system, and a deaerator connected with the medium-pressure cylinder; and the input end of the deaerator is connected with the low pressure feeding system.

In some possible embodiments, the low-pressure feeding system comprises a low-pressure feeding device, a low-pressure feeding device and a low-pressure feeding device, which are sequentially connected with the deaerator;

the low pressure cylinder and the high pressure cylinder are connected with a medium pressure cylinder or a low pressure cylinder; the low pressure cylinder is connected with the low pressure cylinder;

the hydrophobic system is connected with the lower heater.

In some possible embodiments, a fourth low plus hydrophobic pipeline is further arranged between the low plus four and the low plus three, a third low plus hydrophobic pipeline is further arranged between the low plus three and the low plus two, and a second low plus hydrophobic pipeline is further arranged between the low plus two and the low plus one; the condenser is connected with the lower-plus-one part; a first low pressure drainage pipeline is also arranged between the first low pressure drainage pipeline and the condenser;

a hydrophobic isolation valve is arranged on the third low-pressure drainage pipeline; and the third low plus hydrophobic pipeline is connected with a hydrophobic system.

In some possible embodiments, the intermediate pressure cylinder is provided with a heating steam extraction pipeline, and the low heating tee is connected with the heating steam extraction pipeline through a heating steam extraction and return pipeline; the heat supply steam extraction heat return pipeline is sequentially provided with a heat supply steam extraction heat return check valve, a heat supply steam extraction heat return regulating valve and a heat supply steam extraction heat return shutoff valve; the heat supply steam extraction regenerative shutoff valve is arranged between the low heating valve III and the heat supply steam extraction regenerative regulating valve.

In some possible embodiments, the low plus three is connected with the low pressure cylinder through a number three low plus steam extraction line; the third low pressure steam extraction pipeline is sequentially provided with a steam extraction check valve and a steam extraction shutoff valve; the steam extraction shutoff valve is positioned between the steam extraction check valve and the lower valve.

In some possible embodiments, the low-plus system further comprises a bypass outlet shutoff valve disposed between the low plus three and the low plus two, a bypass inlet shutoff valve disposed at the low plus one input.

In some possible embodiments, the low pressure feed system further comprises a bypass conduit, a bypass valve mounted on the bypass conduit; one end of the bypass pipeline is connected with a pipeline between the low-plus-three valve and the bypass outlet shutoff valve, and the other end of the bypass pipeline is connected with the input end of the bypass inlet shutoff valve.

In some possible embodiments, the input of the bypass inlet shutoff valve is connected to a condensate line.

In some possible embodiments, the drainage system comprises a drain and expansion pipeline connected with a third low plus drainage pipeline, a drain regulating valve installed on the drain and expansion pipeline, and a drain flash tank connected with the output end of the drain and expansion pipeline.

In some possible embodiments, a heat supply butterfly valve is installed on the communicating pipe.

Compared with the prior art, the invention has the beneficial effects that:

the invention effectively realizes that the water temperature at the inlet of the deaerator is increased under the condition that the unit is in the cylinder cutting working condition, and the deaerator ensures the deaerating capability;

after the cylinder of the low-pressure cylinder is cut, the system fully utilizes the low-pressure heater which needs to be cut off for heat exchange, so that the outlet water temperature of the deaerator is improved, and the deaerator is ensured not to have high supercooling degree of condensed water generated by the operation of an ultra-heat load and influence on the operation safety of a unit due to high oxygen content;

the invention fully utilizes the middle exhaust steam extraction after cylinder cutting to heat the condensed water, correspondingly reduces the steam extraction amount of a deaerator (high energy level) or even a higher energy level, and improves the economical efficiency of unit operation;

the heat supply steam extraction heat return pipeline is led out from the steam extraction pipeline, and is provided with the regulating valve to regulate the steam extraction pressure, so that the interstage pressure difference of the heater is met, the drainage step-by-step self-flow of the original system is realized, and the compatibility of the original control system is high.

The system of the invention has the advantages of small change, no influence on the original thermodynamic system, high reliability, flexible operation, low investment cost and short construction period, and can be used for the transformation of newly built units or old machines.

Drawings

FIG. 1 is a schematic diagram of the connection relationship of the present invention;

wherein: 1. an intermediate pressure cylinder; 2. a low pressure cylinder; 3. a deaerator; 4. adding four for low; 5. adding three for low; 6. adding two at low; 7. adding one less; 8. a third low pressure steam extraction pipeline; 9. a communicating pipe; 10. a heat supply steam extraction pipeline; 11. a heat supply steam extraction heat return pipeline; 12. a condensate line; 13. a third low plus drain line; 14. dredging and expanding a pipeline; 15. a drain regulating valve; 16. a heat supply butterfly valve; 17. a heat supply steam extraction heat return check valve; 18. a heat supply steam extraction heat return regulating valve; 19. a heat supply steam extraction heat regeneration shutoff valve; 20. a steam extraction check valve; 21. a steam extraction shutoff valve; 22. a bypass inlet shutoff valve; 23. a bypass outlet shutoff valve; 24. a bypass valve; 25. a hydrophobic isolation valve; 26. a hydrophobic flash tank; 27. a first low plus drain line; 28. a condenser; 31. a fourth low plus drain line; 32. and a second low plus hydrophobic pipeline.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail and completely with reference to the accompanying drawings. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.

In the description of the present invention, it is to be understood that the terms indicating an orientation or positional relationship are based on the orientation or positional relationship shown in the drawings only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the drawings of the present invention, it should be understood that different technical features which are not mutually substituted are shown in the same drawing only for the convenience of simplifying the drawing description and reducing the number of drawings, and the embodiment described with reference to the drawings does not indicate or imply that all the technical features in the drawings are included, and thus the present invention is not to be construed as being limited thereto.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; either directly or indirectly through intervening media, either internally or in any other relationship. Reference herein to "first," "second," and similar words, does not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. In the implementation of the present application, "and/or" describes an association relationship of associated objects, which means that there may be three relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In the description of the embodiments of the present application, the meaning of "a plurality" means two or more unless otherwise specified. For example, the plurality of positioning posts refers to two or more positioning posts. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The present invention will be described in detail below.

As shown in fig. 1, a low-pressure cylinder cutting heat supply unit low-pressure heating system comprises a medium pressure cylinder 1, a low pressure cylinder 2 communicated with the medium pressure cylinder 1 through a communication pipe 9, a low-pressure heating system connected with the medium pressure cylinder 1, a drainage system connected with the low-pressure heating system, and a deaerator 3 connected with the medium pressure cylinder 1; and the input end of the deaerator 3 is connected with a low pressure feeding system.

In some possible embodiments, the low-pressure feeding system comprises a low-pressure feeding system and a low-pressure feeding system, wherein the low-pressure feeding system comprises a low-pressure feeding system and a low-pressure feeding system, the low-pressure feeding system is connected with a deaerator 3, the low-pressure feeding system comprises a low-pressure feeding system and a low-pressure feeding system, the low-pressure feeding system is connected with a low-pressure deaerator 3, the low-pressure feeding system comprises a low-pressure feeding system and a low-pressure feeding system, the low-pressure feeding system is connected with the low-pressure feeding system, and the low-pressure feeding system, and the low-pressure;

the low pressure cylinder 4 is connected with the intermediate pressure cylinder 1 or the low pressure cylinder 2; the low pressure cylinder 3 and the low pressure cylinder 2 are respectively connected with the low pressure cylinder 3 and the low pressure cylinder 2, and the low pressure cylinder 6 and the low pressure cylinder 7 are respectively connected with the low pressure cylinder 2;

the hydrophobic system is respectively connected with the lower part plus three 5 and the lower part plus one 7.

Preferably, the lower plus two 6 and the lower plus one 7 are arranged at the throat part of the condenser.

In some possible embodiments, a fourth low plus hydrophobic pipeline 31 is further arranged between the low plus four 4 and the low plus three 5, a third low plus hydrophobic pipeline 13 is further arranged between the low plus three 5 and the low plus two 6, and a second low plus hydrophobic pipeline 32 is further arranged between the low plus two 6 and the low plus one 7; the condenser 28 is connected with the lower-plus-one 7; a first low pressure drainage pipeline 27 is also arranged between the first low pressure addition 7 and the condenser 28;

a hydrophobic isolation valve 25 is arranged on the third low-pressure drainage pipeline 13; the third low plus hydrophobic pipeline 13 is connected with a hydrophobic system.

Through the arrangement, the drained water with the addition of four 4, the three 5, the two 6 and the one 7 flows automatically step by step through the drainage pipeline, and is drained into the condenser 28.

In some possible embodiments, the intermediate pressure cylinder 1 is provided with a heating steam extraction line 10, and the low heating cylinder 5 is connected with the heating steam extraction line 10 through a heating steam extraction heat return line 11; the heat supply steam extraction heat return pipeline 11 is sequentially provided with a heat supply steam extraction heat return check valve 17, a heat supply steam extraction heat return regulating valve 18 and a heat supply steam extraction heat return shutoff valve 19; the heat supply extraction steam regenerative shutoff valve 19 is arranged between the low heating valve III 5 and the heat supply extraction steam regenerative regulating valve 18.

The heat supply steam extraction heat return pipeline 11 is connected to a third low-pressure steam extraction pipeline 8 from a heat supply steam extraction pipeline 10 for discharging steam from the intermediate pressure cylinder 1, and after the steam extraction shut-off valve 21 is located at the merging position, a heat supply steam extraction heat return check valve 17, a heat supply steam extraction heat return adjusting valve 18 and a heat supply steam extraction heat return shut-off valve 19 are sequentially arranged from the heat supply steam extraction pipeline 10 to the third low-pressure steam extraction pipeline 5.

In some possible embodiments, the low plus three 5 is connected to the low pressure cylinder 2 through a No. three low plus steam extraction line 8; the third low pressure steam extraction pipeline 8 is sequentially provided with a steam extraction check valve 20 and a steam extraction shutoff valve 21; the extraction shutoff valve 21 is located between the extraction check valve 20 and the low plus three 5.

In some possible embodiments, the low-plus system further comprises a bypass outlet shutoff valve 23 between the low plus three 5 and low plus two 6 setting, a bypass inlet shutoff valve 22 setting at the input of the low plus one 7.

In some possible embodiments, the low pressure addition system further comprises a bypass conduit, a bypass valve 24 mounted on the bypass conduit; one end of the bypass pipeline is connected with the pipeline between the low plus three 5 and the bypass outlet shutoff valve 23, and the other end of the bypass pipeline is connected with the input end of the bypass inlet shutoff valve 22.

In some possible embodiments, the input of the bypass inlet shutoff valve 22 is connected to the condensate line 12.

In some possible embodiments, the drainage system comprises a drain and drain line 14 connected with a third low plus drain line 13, a drain regulating valve 15 installed on the drain and drain line 14, and a drain flash tank 26 connected with the output end of the drain and drain line 14.

The drain and drain pipeline 14 is led out from the front of the drain and drain isolation valve 25 and connected to a drain flash tank 26.

In some possible embodiments, the communicating tube 9 is provided with a heating butterfly valve 16.

Example 1:

this embodiment is shown in FIG. 1: the embodiment provides a low heating and back heating system of a low-pressure cylinder 2-cylinder-cutting heat supply unit, wherein in the running process of the unit under a pure condensation working condition, a heat supply butterfly valve 16 is opened, and a heat supply steam extraction back heating check valve 17 and a heat supply steam extraction back heating shutoff valve 19 are closed; opening the steam extraction check valve 20 and the steam extraction shutoff valve 21; opening a bypass inlet shutoff valve 22 and a bypass outlet shutoff valve 23, closing a bypass valve 24, and enabling condensed water to flow through a low-plus-one (7), a low-plus-two (6), a low-plus-three (5) and a low-plus-four (4) in sequence to enter a deaerator 3 for thermal deoxidization; opening the hydrophobic isolation valve 25 and closing the hydrophobic adjusting valve 15; draining water with the volume of four 4 low, three 5 low, two 6 low and one 7 low flows automatically step by step through a draining pipeline, and the draining water is discharged into a condenser 28; the operating mode of the working condition is consistent with the original operating mode.

Example 2:

this embodiment is substantially the same as embodiment 1, except that: when the unit is in operation under the heat supply working condition, the heat supply butterfly valve 16 is partially opened.

Example 3:

this embodiment is substantially as shown in fig. 1: the embodiment provides a low heating and back heating system of a low-pressure cylinder 2 cylinder-cutting heat supply unit, wherein in the working condition of cylinder-cutting heat supply, a heat supply butterfly valve 16 is closed to realize cylinder cutting, a steam extraction check valve 20 and a steam extraction shutoff valve 21 are closed to cut off a steam extraction source of a low-pressure cylinder 2 with three 5 heating devices; opening a heat supply steam extraction regenerative check valve 17 and a heat supply steam extraction regenerative shutoff valve 19 to introduce the exhausted steam of the intermediate pressure cylinder 1 into the low pressure heater 5 to exchange heat with the condensed water and heat the condensed water; meanwhile, the heat supply steam extraction heat return regulating valve 18 is opened to adjust the steam extraction pressure, and the interstage pressure difference of low plus three 5 and low plus four 4 is maintained in a reasonable range; simultaneously closing the hydrophobic isolation valve 25 and opening the hydrophobic adjusting valve 15 for hydrophobic treatment; closing the bypass inlet shutoff valve 22 and the bypass outlet shutoff valve 23, opening the bypass valve 24, and cutting off the low plus one 7 and the low plus two 6; the condensed water sequentially flows through a low-plus-three (5) and a low-plus-four (4) and enters a deaerator (3) for thermal deoxidization; the low plus four 4 drains are gravity fed through drain lines to low plus three 5 drains and the low plus three 5 drains are discharged to a drain flash tank 26.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.