Automatic steam source switching system of feed pump turbine

Abstract

The utility model discloses an automatic steam source switching system of a water-feeding pump turbine, which can supply steam reliably by multiple steam sources and comprises a main engine four-section steam extraction and supply system and an auxiliary steam main pipe steam supply system. A check valve and an electric isolation valve are arranged on a steam supply pipeline for extracting steam from a main engine to a water-feeding pump turbine in four sections, a check valve and a manual isolation valve are arranged on a steam supply pipeline for assisting steam to the water-feeding pump turbine, and steam can be supplied to the front of a main steam valve of the water-feeding pump turbine through two paths of steam supply, so that steam is provided for the turbine; wherein auxiliary steam is provided by an auxiliary steam main pipe, and a steam source of the auxiliary steam main pipe is provided by a main engine four-section extraction steam and main engine low-temperature reheat steam supply door. According to the system, the steam source of the small steam turbine can be automatically switched when the unit is under the high-load and low-load working conditions only by adjusting the working state of equipment. In low load, throttling loss caused by small opening degree of the adjusting valve of the medium-low pressure communicating pipe of the main engine is avoided, the working state of the low-pressure cylinder is improved, and the working efficiency of the main engine is superior to that of the throttling operation mode of the adjusting valve of the medium-low pressure communicating pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine systems, in particular to an automatic switching system for steam sources of a water feed pump steam turbine. Background Art

[0002] 300MW thermal power generating units usually have two steam-driven feedwater pumps to supply water to the boiler. The small steam turbine that drives the feedwater pump is provided with steam source by the four-extraction steam of the main engine as the normal operation steam source. In addition, an auxiliary steam source is provided by the auxiliary steam main pipe. During the heating transformation of the unit, in order to improve the heating capacity of the medium-pressure cylinder exhaust steam, an adjustment gate is installed between the medium-pressure cylinder exhaust steam and the low-pressure cylinder inlet steam to increase the medium-pressure cylinder exhaust steam pressure (also the four-extraction pressure).

[0003] With the increasing amount of renewable energy power generation, deep peak regulation of thermal power units has become the norm. When 30% Pe deep peak regulation is carried out, the four-extraction pressure is relatively low and cannot meet the working needs of small steam turbines. Therefore, the four-extraction pressure is increased by closing the connecting pipe of the medium and low-pressure cylinders and adjusting the gate pressure. This operation method can meet the working needs of small steam turbines, but it will cause the working efficiency of the main engine to decrease. Utility Model Content

[0004] In view of the above-mentioned technical deficiencies, the purpose of the utility model is to provide an automatic switching system for the steam source of a feed pump turbine, which connects the auxiliary steam source and the four-extraction steam source of the small steam turbine in parallel to provide steam source to the small steam turbine, thereby improving the working efficiency of the main engine.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] The utility model provides a steam source automatic switching system for a water pump steam turbine, including reliable steam supply from multiple steam sources, including a main engine four-stage extraction steam supply system and an auxiliary steam main pipe steam supply system; a steam supply pipeline from the main engine four-stage extraction steam to the water pump steam turbine is provided with a check valve and an electric isolation door, and a steam supply pipeline from the auxiliary steam to the water pump steam turbine is provided with a check valve and a manual isolation door, and both steam supply routes can supply steam to the front of the main steam valve of the water pump steam turbine to provide steam for the steam turbine;

[0007] The auxiliary steam is provided by the auxiliary steam main pipe, and the steam source of the auxiliary steam main pipe is provided by the four-stage extraction steam of the main engine and the low-temperature reheat steam of the main engine; an automatic adjustment door is set from the low-temperature reheat steam to the auxiliary steam main pipe; the auxiliary steam main pipe provides steam source for multiple equipment, including providing steam source to the feed water pump turbine.

[0008] The beneficial effect of the utility model is that the utility model system does not require any equipment investment or modification, and only by adjusting the working state of the equipment, the unit can automatically switch the steam source of the small steam turbine under high and low load conditions. Under low load, the throttling loss caused by the small opening of the medium and low pressure connecting pipe adjustment door of the main engine is avoided, the working state of the low pressure cylinder is improved, and the working efficiency of the main engine is better than the operation mode of throttling of the medium and low pressure cylinder connecting pipe adjustment door. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 This is a schematic diagram of the auxiliary steam main pipe steam supply system of the feedwater pump turbine steam source automatic switching system provided in Example 1 of the utility model.

[0011] Figure 2 This is a schematic diagram of the automatic switching system for the steam source of a feedwater pump turbine provided in Example 1 of the utility model. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Example 1

[0013] The steam source automatic switching system for the feedwater pump steam turbine includes the steam supply system from the main engine four-stage extraction steam and the auxiliary steam to the feedwater pump steam turbine. The steam supply pipeline from the main engine four-stage extraction steam to the feedwater pump steam turbine is equipped with a check valve and an electric isolation door, and the steam supply pipeline from the auxiliary steam to the feedwater pump steam turbine is equipped with a check valve and a manual isolation door. Both steam supply routes can supply steam to the main steam valve of the feedwater pump steam turbine to provide steam for the steam turbine. Figure 2 shown.

[0014] The auxiliary steam is provided by the auxiliary steam main pipe, and the steam source of the auxiliary steam main pipe is provided by the four-stage extraction steam of the main engine and the low-temperature reheat steam of the main engine. An automatic adjustment gate is set from the low-temperature reheat steam to the auxiliary steam main pipe, and the steam supply pressure constant value can be set (for example, when the automatic adjustment gate is set to 0.5MPa, when the four-stage extraction steam pressure is higher than 0.5MPa, the four-stage extraction steam supplies steam to the auxiliary steam main pipe, and the auxiliary steam main pipe pressure and the four-stage extraction steam pressure are basically the same, and the low-temperature reheat steam to the auxiliary steam main pipe adjustment gate is automatically closed. When the four-stage extraction steam pressure is lower than 0.5MPa, the auxiliary steam main pipe pressure is reduced accordingly, and the low-temperature reheat steam to the auxiliary steam main pipe adjustment gate is automatically opened to supply steam to the auxiliary steam main pipe, maintaining the auxiliary steam main pipe pressure at 0.5MPa). The auxiliary steam main pipe provides steam source for multiple equipment, including providing steam source to the feedwater pump turbine. Figure 1 shown.

[0015] Working principle:

[0016] The steam pipeline from the fourth extraction to the small steam turbine is provided with a check valve, and the steam pipeline from the auxiliary steam to the small steam turbine is also provided with a check valve. When the fourth extraction steam and the auxiliary steam supply steam to the small steam turbine at the same time, the high-pressure steam can enter the small steam turbine, and the low-pressure steam cannot enter the small steam turbine. Due to the check valve, steam return will not occur.

[0017] When the unit load is high, the four-extraction steam pressure is relatively high, and the steam for the small turbine is provided by the four-extraction steam, which is a normal working mode.

[0018] When the unit load decreases, the four-extraction steam pressure decreases accordingly. When the four-extraction steam pressure is lower than the auxiliary steam pressure, the auxiliary steam can automatically supply steam to the small turbine.

[0019] When the unit load gradually increases, the four-extraction steam pressure increases accordingly. When the four-extraction steam pressure is higher than the auxiliary steam pressure, the four-extraction steam is restored to the normal mode of supplying steam to the small turbine.

[0020] This system does not require any equipment investment or modification. It can automatically switch the steam source of the small steam turbine under high and low load conditions by adjusting the working state of the equipment. At low load, it avoids the throttling loss caused by the small opening of the medium and low pressure connecting pipe adjustment door of the main engine, improves the working state of the low pressure cylinder, and makes the working efficiency of the main engine better than the operation mode of throttling of the medium and low pressure cylinder connecting pipe adjustment door.

[0021] The system has multiple steam sources for reliable steam supply, including four-stage extraction steam supply from the main engine and auxiliary steam main pipe supply. Both steam sources can supply steam to the main steam valve of the feedwater pump turbine, providing it with reliable and stable working steam.

[0022] This system adjusts the valve status of the steam turbine steam system to achieve automatic switching of the steam source of the feed pump turbine between four-stage extraction steam and auxiliary steam when the main engine load changes significantly.

[0023] This system does not require additional transformation investment. By innovating the operation mode of the steam supply system, it not only ensures the reliability of the steam source for the feedwater pump turbine, but also avoids a significant drop in the efficiency of the main engine during deep peak regulation.

[0024] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. The automatic switching system of steam source for feedwater pump turbine is characterized by: Reliable steam supply from multiple steam sources, including the main engine four-stage extraction steam supply system and the auxiliary steam main pipe steam supply system; the main engine four-stage extraction steam to the feedwater pump steam turbine steam supply pipeline is equipped with a check valve and an electric isolation door, and the auxiliary steam to the feedwater pump steam turbine steam supply pipeline is equipped with a check valve and a manual isolation door. Both steam supply routes can supply steam to the main steam valve of the feedwater pump steam turbine to provide steam for the steam turbine; The auxiliary steam is provided by the auxiliary steam main pipe, and the steam source of the auxiliary steam main pipe is provided by the four-stage extraction steam of the main engine and the low-temperature reheat steam of the main engine; an automatic adjustment door is set from the low-temperature reheat steam to the auxiliary steam main pipe; the auxiliary steam main pipe provides steam source for multiple equipment, including providing steam source to the feed water pump turbine.

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