A plant-level multi-unit coupling system to improve the flexibility of thermal power units

Abstract

The present invention discloses a plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units, including a peak-shaving boiler, a superheater, a small steam turbine, a generator, and a condensate leveling system; the main steam pipeline is connected to the outlet of the superheater, the small steam turbine is connected to the main steam pipeline through a steam flow regulating valve and a first pressure gauge, and the outlet of the small steam turbine is connected to the reheater inlet pipeline of other units in the plant through a pressure regulating valve and a second pressure gauge. This system extracts part of the main steam to reduce the power generation load under the premise that the load of the peak-shaving boiler remains unchanged. After the main steam is extracted, it passes through a small steam turbine and enters other units as reheat steam, thereby improving the energy utilization rate. The electricity generated by the small steam turbine is used for the plant power system in the plant, reducing the plant power consumption rate of each unit. This system can achieve deep peak-shaving and safe and stable operation of thermal power units, and has low investment costs.

Description

Technical Field

[0001] The invention belongs to the technical field of generator sets, and relates to a plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units. Background Art

[0002] At present, thermal power is facing the risk of structural overcapacity, and new energy is facing great pressure to absorb. Therefore, thermal power is bound to face deep peak regulation in order to make way for the development of new energy. Thermal power units are divided into heating units and non-heating units according to whether they undertake civil heating.

[0003] For the "Three Norths" region, the contradiction between wind and fire during the heating period is particularly prominent. The best period of wind resources is during the winter heating period. The growing demand for heating and the continuous increase in clean energy installed capacity have resulted in very limited peak-shaving space. Especially in the Northeast, most of the thermal power units are cogeneration units, and the peak-shaving capacity is only 10-20%, which affects the consumption of new energy stocks and the development of new energy increments. The hard gap in peak-shaving capacity has caused serious new energy power restrictions in some areas. The deep peak-shaving of heating units is mainly to solve the problem of thermal and electric decoupling, and the research in this area is relatively in-depth and the technology is relatively mature. Commonly used technologies include heat storage tanks and electrode boilers.

[0004] For non-heating units, deep peak regulation is currently mainly achieved through combustion system modification to improve the stable combustion characteristics of the units. However, due to the poor quality and unstable coal quality of domestic coal, the modified units have different degrees of safety issues such as boiler low-load stable combustion and hydrodynamic circulation, full-load denitrification device and low-load cooling of steam turbines, control system flexibility during long-term low load and rapid load changes, equipment operation cycle and life attenuation, etc., all of which need to be further optimized and resolved. Non-heating units are large in size. If their peak regulation capabilities can be improved, the proportion of new energy consumption in the entire power grid can be significantly increased. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units. The system can achieve deep peak regulation and safe and stable operation of thermal power units with low investment cost.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A plant-level multi-unit coupling interoperation system for improving the flexibility of thermal power units includes a peak-shaving boiler, a small steam turbine and a generator; a superheater is arranged in the peak-shaving boiler, the outlet of the superheater is connected to a main steam pipeline, the main steam pipeline is connected to an inlet of the small steam turbine, and the outlet of the small steam turbine is connected to an inlet of a reheater inlet pipeline and the generator.

[0008] A further improvement of the present invention is that the small steam turbine is a back pressure unit.

[0009] A further improvement of the present invention is that the power generation of the small steam turbine is 10% of the power generation of the unit at full load.

[0010] A further improvement of the present invention is that the main steam pipeline is connected to the inlet of the small steam turbine via a steam flow regulating valve.

[0011] A further improvement of the present invention is that a first pressure gauge is provided between the steam flow regulating valve and the small steam turbine.

[0012] A further improvement of the present invention is that the steam flow regulating valve is started when the load of the peak load regulating unit is lower than 40%.

[0013] A further improvement of the present invention is that the outlet of the small steam turbine is connected to the inlet of the reheater inlet pipeline via a pressure regulating valve.

[0014] A further improvement of the present invention is that a second pressure gauge is provided between the pressure regulating valve and the reheater inlet pipe.

[0015] A further improvement of the present invention is that it also includes a condensate leveling system, which includes a condenser, a condensate flow regulating valve, a water pump and a peak-shaving unit condenser; there are several condensers, and the outlet of each condenser is connected to the water pump via a condensate flow regulating valve, the water pump is connected to the condenser of the peak-shaving unit, and the outlet of the reheater inlet pipe is connected to the inlet of each condenser.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units described in the present invention reduces the power generation load of the peak-shaving unit by extracting the main steam of the peak-shaving unit under the condition that the boiler load remains unchanged, and the reduction range is as high as 10% of the full-load power generation of the unit, which greatly improves the flexibility of the unit's deep peak regulation. After the main steam drives the motor to generate electricity through the small steam turbine, it is cooled and reduced in pressure and passed into the cold re-steam pipeline of other units in the plant. Under the premise that the boiler load remains unchanged, the power generation load of other units is increased, and the electricity generated by the small steam turbine is used for the plant power system of all units in the plant, thereby minimizing the energy consumption loss of the unit during the flexible peak regulation process, improving the stability of boiler operation, and having a low investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the system of the present invention;

[0019] Figure 2 It is a schematic diagram of the condensate leveling system in the present invention.

[0020] Among them, 1 is the peak-shaving boiler, 2 is the superheater, 3 is the main steam pipeline, 4 is the steam flow regulating valve, 5 is the first pressure gauge, 6 is the small steam turbine, 7 is the generator, 8 is the pressure regulating valve, 9 is the second pressure gauge, 10 is the reheater inlet pipeline, 11 is the condenser of other units in the plant, 12 is the condensate flow regulating valve, 13 is the water pump, and 14 is the condenser of the peak-shaving unit. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0023] In addition, when an element in the present invention is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0024] refer to Figure 1 and Figure 2 The plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units described in the present invention comprises a peak-shaving boiler 1, a small steam turbine 6, a generator 7 and a condensate leveling system;

[0025] A superheater 2 is provided in the peak-shaving boiler 1, and the outlet of the superheater 2 is connected to the main steam pipeline 3, and the main steam pipeline 3 is connected to the inlet of the small steam turbine 6 through the steam flow regulating valve 4 and the first pressure gauge 5, and the outlet of the small steam turbine 6 is connected to the inlet of the reheater inlet pipeline 10 of other units in the plant through the pressure regulating valve 8 and the second pressure gauge 9. The outlet of the reheater inlet pipeline 10 is connected to the condensate leveling system.

[0026] The small steam turbine 6 is connected to the generator 7, and the generated electricity is connected to the factory power system.

[0027] The small steam turbine 6 is a back pressure unit.

[0028] The power generation of the small steam turbine 6 is 10% of the power generation of the unit at full load.

[0029] The condensate leveling system includes condensers 11, condensate flow regulating valves 12, water pumps 13 and peak load condensers 14 of other units in the plant; there are several condensers 11, and the outlet of each condenser 11 is connected to the water pump 13 via the condensate flow regulating valve 12, and the water pump is connected to the peak load condenser 14. The outlet of the reheater inlet pipe 10 is connected to the inlet of each condenser 11.

[0030] The steam flow regulating valve 4 is started when the load of the peak load regulating unit is lower than 40%.

[0031] The adjustment method of this system is:

[0032] The steam flow regulating valve 4 is controlled jointly by the unit power generation load and the boiler load. On the premise that the power generation load meets the dispatching requirements, the boiler load is kept not less than 35% and the boiler load is increased as much as possible.

[0033] The pressure regulating valve 8 is controlled by the second pressure gauge 9 behind the valve, so that the steam is reduced in pressure after passing through the pressure regulating valve 8 to the pressure behind the valve indicated by the second pressure gauge 9. The pressure regulating valve 8 corresponding to the second pressure gauge 9 with the largest reading on different branches is fully open.

[0034] The back pressure of the small steam turbine 6 is determined by the reheater inlet pipe 10 of the branch where the second pressure gauge 9 with the largest reading is located.

[0035] The condensate flow regulating valve 12 is determined by the deaerator water level of the unit. By adjusting the condensate flow regulating valve 12, the deaerator water level of the unit is kept constant.

[0036] The specific working process of the present invention is:

[0037] When the load of the peak-shaving unit is lower than 40%, the load continues to decrease, and the peak-shaving boiler 1 will face low-load stable combustion and water dynamic problems. At this time, the load of the peak-shaving boiler 1 is kept unchanged, and part of the main steam is extracted to reduce the power generation load. The power generation load is reduced under the premise that the load of the peak-shaving boiler 1 remains unchanged. After the main steam is extracted, it is cooled and depressurized by the small steam turbine 6, and passed into the reheater inlet pipe 10 of other units in the plant, and enters the inside of other units as reheated steam, which improves the energy utilization rate. The small steam turbine 6 is connected to the generator 7, and the electricity generated is used for the plant power system in the plant, reducing the plant power rate of each unit and further improving the energy utilization rate. In addition, the condensate flow rate of each unit is balanced through the condensate flow regulation system. This system can achieve deep peak regulation and safe and stable operation of thermal power units, and the investment cost is low.

[0038] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units, characterized in that: The peak-shaving boiler (1) comprises a small steam turbine (6) and a generator (7); a superheater (2) is arranged in the peak-shaving boiler (1); the outlet of the superheater (2) is connected to a main steam pipeline (3); the main steam pipeline (3) is connected to an inlet of the small steam turbine (6); the outlet of the small steam turbine (6) is connected to an inlet of a reheater inlet pipeline (10) of another unit and the generator (7); The main steam pipeline (3) is connected to the inlet of the small steam turbine (6) via the steam flow regulating valve (4); The steam flow regulating valve (4) is activated when the load of the peak load regulating unit is lower than 40%; The outlet of the small steam turbine (6) is connected to the inlet of the reheater inlet pipe (10) of another unit through a pressure regulating valve (8); It also includes a condensate leveling system, which includes a condenser (11), a condensate flow regulating valve (12), a water pump (13) and a peak-shaving unit condenser (14); there are a plurality of condensers (11), the outlet of each condenser (11) is connected to the water pump (13) via the condensate flow regulating valve (12), the water pump is connected to the peak-shaving unit condenser (14), and the outlets of the reheater inlet pipes (10) of other units are connected to the inlet of each condenser (11).

2. A plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units according to claim 1, characterized in that: The small steam turbine (6) is a back pressure unit.

3. A plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units according to claim 1, characterized in that: The power generation of the small steam turbine (6) is 10% of the power generation of the unit at full load.

4. A plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units according to claim 1, characterized in that: A first pressure gauge (5) is provided between the steam flow regulating valve (4) and the small steam turbine (6).

5. A plant-level multi-unit coupling intermodal system for improving the flexibility of thermal power units according to claim 1, characterized in that: A second pressure gauge (9) is provided between the pressure regulating valve (8) and the inlet pipe (10) of the reheater of another unit.

Images