Auxiliary steam system running based on deep peak regulation working condition

Abstract

The utility model relates to an auxiliary steam system operating based on a deep peak regulation working condition, and solves the technical problem that in the prior art, when a plurality of adjacent units of the same power plant enter the deep peak regulation working condition to operate at the same time, the auxiliary steam system cannot supply steam to steam using systems of the adjacent units. The device comprises a reheating cold section, wherein the reheating cold section is connected with a spare steam mother pipe through a steam extraction pipeline; the spare steam mother pipe is connected with the spare steam header through a spare steam header pressure regulating valve group; the standby steam header is connected with the standby steam header of the adjacent unit through a connecting pipe; an auxiliary steam extraction pipeline is further connected between the reheating cold section and the steam preparation main pipe; a first auxiliary gate valve, an auxiliary check valve and a second auxiliary gate valve are sequentially installed on the auxiliary steam extraction pipeline in the steam circulation direction. An auxiliary emptying pipeline and an auxiliary drainage pipeline are connected to the position, between the auxiliary check valve and the second auxiliary gate valve, of the auxiliary steam extraction pipeline; the first auxiliary gate valve is an electric gate valve capable of stopping and is used for being connected with an external monitoring system.

Description

Technical Field

[0001] The utility model relates to a steam turbine unit system, in particular to an auxiliary steam system operating under a deep peak regulation working condition, which is used for a coal-fired thermal power unit. Background Art

[0002] With the rapid development of society and the transformation of energy structures, clean energy has been developed and utilized on a large scale. Coupled with changes in electricity consumption, the demand for flexible peak-shaving power sources is growing. In the context of promoting the widespread use of clean energy and optimizing the electricity consumption structure, the role of traditional coal-fired power plants in the power system is gradually shifting to supporting the stable output of renewable energy. In this context, to achieve efficient operation of the power system and rational energy allocation, coal-fired power plants need to be able to provide additional power output during peak hours and reduce power output during off-peak hours.

[0003] "Deep peak shaving" refers to the ratio of coal-fired power plants' boilers' minimum stable combustion capacity to the maximum level possible. Typically, this load factor ranges from 40% to 30% of rated load. However, due to factors such as increased coal consumption, achieving deep peak shaving presents numerous practical challenges. Therefore, optimizing the operating strategies of coal-fired power plants to support flexible peak shaving in the power system is a pressing technical challenge facing the power industry.

[0004] The auxiliary steam system in existing coal-fired power units (hereinafter referred to as units) is generally connected to the four-stage extraction steam pipeline and the reheat cold section pipeline leading to the boiler reheater. The extraction steam pipeline passes through the extraction steam isolation valve and the extraction steam pressure regulating valve in sequence and then merges into the standby steam main pipe. Then it passes through the standby steam header pressure regulating valve and supporting valves to the standby steam header of the unit. The standby steam headers of multiple units are connected by connecting pipes to connect the auxiliary steam systems of multiple units to each other.

[0005] The auxiliary steam system's steam source comes from the four-stage extraction, the reheat-cold section, the auxiliary steam systems of adjacent units, and the steam consumption system of adjacent power plants. During normal unit operation, the auxiliary steam system is supplied by the four-stage extraction of the main steam turbine. When the unit load falls below 80%, the auxiliary steam system switches from the four-stage extraction to the reheat-cold section (i.e., the reheat-cold section and two-stage extraction under deep peaking conditions). The auxiliary steam pressure is controlled between 0.588 and 0.785 MPa using the extraction pressure regulating valve. During unit startup, load shedding, or shutdown for maintenance, the auxiliary steam system is supplied by the steam consumption system of adjacent units. When the unit load exceeds 70%, the auxiliary steam system is switched to the auxiliary steam system. Therefore, when a single unit enters deep peaking operation, the auxiliary steam system should be supplied by the steam consumption system of the adjacent units.

[0006] However, the existing auxiliary steam system can no longer meet the needs of deep peak regulation. When multiple units in a power plant operate simultaneously in deep peak regulation conditions, the auxiliary steam system will experience insufficient pressure. Furthermore, in the event of an emergency in an adjacent unit, such as a boiler fire or plant power outage, steam cannot be supplied to the adjacent unit's steam system. Insufficient auxiliary steam pressure can prevent users from securing a stable steam supply, leading to unstable steam supply and even major accidents such as insufficient steam feedwater pump output leading to water shortages in the steam drum, and insufficient steam supply pressure to the main engine shaft seal leading to cooling water and air ingress to the turbine. Utility Model Content

[0007] The purpose of the utility model is to solve the technical problem in the prior art that when multiple adjacent units in the same power plant enter deep peak-shaving operation at the same time, the auxiliary steam system cannot supply steam to the steam systems of adjacent units, and to provide an auxiliary steam system operating under deep peak-shaving operation.

[0008] In order to achieve the above objectives, the technical solutions provided by this utility model are as follows:

[0009] An auxiliary steam system operating under deep peak load regulation conditions comprises a cold reheat section leading to a boiler reheater, an extraction steam pipeline connected to the cold reheat section, an extraction steam isolation valve and an extraction steam pressure regulating valve installed in sequence along the steam flow direction on the extraction steam pipeline, and then connected to a standby steam main pipe; a standby steam header pressure regulating valve group is installed on the standby steam main pipe, and its outlet is connected to the standby steam header; the standby steam header is connected to the standby steam headers of other adjacent units via a connecting pipe;

[0010] Its special features are:

[0011] An auxiliary steam extraction pipeline is also connected between the reheat cold section and the standby steam main pipe. The inlet end of the auxiliary steam extraction pipeline is connected to the reheat cold section, and the outlet end is connected to the standby steam main pipe.

[0012] On the auxiliary steam extraction pipeline, a first auxiliary gate valve, an auxiliary check valve and a second auxiliary gate valve are installed in sequence along the steam flow direction;

[0013] The auxiliary steam extraction pipeline is located between the auxiliary check valve and the second auxiliary gate valve, and is connected to the auxiliary drain pipeline and the auxiliary drain pipeline through valves respectively, for the pipe warming operation before commissioning;

[0014] The first auxiliary gate valve is a stoppable electric gate valve used to connect to an external monitoring system to quickly cut off the steam source in the event of pipeline overpressure or other emergency conditions.

[0015] Furthermore, the auxiliary exhaust pipe and the auxiliary drain pipe are both arranged on the auxiliary steam extraction pipe between the auxiliary check valve and the second auxiliary gate valve.

[0016] Furthermore, the auxiliary exhaust pipe is arranged on the auxiliary steam extraction pipe at a side close to the auxiliary check valve; the auxiliary drain pipe is arranged on the auxiliary steam extraction pipe at a side close to the second auxiliary gate valve.

[0017] Furthermore, the first auxiliary gate valve adjusts the auxiliary steam pressure in the auxiliary steam extraction pipeline in a range of 0.588 to 0.785 MPa.

[0018] Furthermore, the second auxiliary gate valve is a manual gate valve, which is used to isolate the gas source during maintenance.

[0019] Furthermore, the first auxiliary gate valve is connected to an external DCS control system.

[0020] Furthermore, the inlet access point of the auxiliary steam extraction pipeline is located on the reheat cold section, before the inlet access point of the steam extraction pipeline; the outlet access point of the auxiliary steam extraction pipeline is located on the standby steam main pipe, before the standby steam manifold pressure regulating valve group.

[0021] Furthermore, the spare steam manifold pressure regulating valve group includes a first switch valve, a spare steam pressure regulating valve and a second switch valve installed in sequence along the steam flow direction, and a third switch valve connected in parallel with the first switch valve, the pressure regulating valve and the second switch valve.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention provides an auxiliary steam system operating under deep peak-shaving conditions. This system is modified by adding a steam extraction scheme to the reheat cold section. This scheme involves adding an auxiliary steam extraction pipeline and corresponding first auxiliary gate valves, auxiliary check valves, and second auxiliary gate valves, and performing thermal control. The auxiliary steam pressure of each unit in the same power plant is controlled by opening and closing the first auxiliary gate valve when it enters deep peak-shaving conditions. This increases the steam extraction volume of the reheat steam system, improving the flow and pressure of the auxiliary steam to ensure the normal operation of each auxiliary system of the unit. This provides sufficient plant steam for the auxiliary steam systems of multiple units in the same power plant, increasing the reliability of the plant steam pressure supply. Furthermore, while improving the flexibility of the auxiliary steam system, it ensures the safe operation of the units. The auxiliary steam system can also serve as a backup for the original steam extraction system, alternating between online maintenance operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural principle diagram of an embodiment of the auxiliary steam system of the utility model operating under deep peak regulation conditions.

[0025] The following are the descriptions of the accompanying figures:

[0026] 01-reheat cold section; 02-extraction steam pipeline; 03-extraction steam isolation valve; 04-extraction steam pressure regulating valve; 05-connecting pipe; 06-standby steam main pipe; 07-standby steam header pressure regulating valve group; 08-steam header;

[0027] 1-First auxiliary gate valve; 2-Auxiliary check valve; 3-Auxiliary exhaust pipe; 4-Auxiliary drain pipe; 5-Second auxiliary gate valve; 6-Auxiliary steam extraction pipe. DETAILED DESCRIPTION

[0028] The specific technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] Coal-fired power plants are typically operated on a plant-by-plant basis, with multiple units simultaneously performing deep peak load regulation. When multiple adjacent units in the same plant, such as 300MW units, simultaneously operate in deep peak load regulation, insufficient auxiliary steam system pressure can occur. This prevents steam from being supplied to the steam systems of adjacent units, and the steam source pressure in these systems cannot be guaranteed.

[0030] The auxiliary steam system ensures safe and reliable startup and shutdown of the unit, provides the necessary steam source with the required parameters and quantity under low load and abnormal operating conditions, and provides steam for production heating to related equipment. Insufficient auxiliary steam system pressure will not guarantee safe operation of the unit.

[0031] The present utility model proposes to add a new steam extraction line (auxiliary steam extraction pipeline) to the reheat cold section of the reheat steam system of this unit and to install relevant equipment in the new pipeline, so that this unit can increase the steam source pressure of this unit under deep regulation conditions while ensuring the stable and sufficient steam source of the adjacent units. That is, one of the units in this plant is renovated, its auxiliary steam system is pressurized, and the normal operation of the auxiliary steam systems of all units in the plant is guaranteed through the communication pipes between the adjacent units. When a single unit is deeply peak-shaving, the gas source of this unit can also be made more stable, which is a supplement to the original steam extraction pipeline. On the premise of improving the flexibility of the auxiliary steam system, it ensures the safety of the unit operation, and can also serve as a backup for the original system and perform online maintenance operations alternately.

[0032] like Figure 1 The figure shows an auxiliary steam system of a unit modified using an embodiment of the present invention operating under deep peak-shaving conditions when all units in the same power plant enter deep peak-shaving conditions at the same time, including a reheating cold section 01 leading to the boiler reheater. The reheating cold section 01 is used to send the steam that has done part of the work in the turbine back to the boiler for reheating and returning to the turbine to do work again.

[0033] The reheat cold section 01 is connected to an extraction steam pipeline 02, on which an extraction steam isolation valve 03 and an extraction steam pressure regulating valve 04 are installed in sequence along the steam flow direction, and then connected to the standby steam main pipe 06; a standby steam header pressure regulating valve group 07 is installed on the standby steam main pipe 06, and its outlet is connected to the standby steam header 08; the standby steam header 08 is connected to the standby steam headers of other adjacent units through a connecting pipe 05; specifically, each unit is equipped with a standby steam header with a pressure of 0.588~0.785MPa and a temperature of 250℃.

[0034] An auxiliary steam extraction pipeline 6 is also connected between the reheat cold section 01 and the standby steam main pipe 06. In other embodiments of the present invention, it can also be connected to other places, depending on the actual layout of the original pipeline, as long as the pressure level is the same.

[0035] The inlet of the auxiliary steam extraction pipeline 6 is connected to the cold reheat section 01, and the outlet is connected to the standby steam main pipe 06. The inlet of the auxiliary steam extraction pipeline 6 is located on the cold reheat section 01, before the inlet of the steam extraction pipeline 02. The outlet of the auxiliary steam extraction pipeline 6 is located on the standby steam main pipe 06, before the standby steam header pressure regulating valve group 07. The standby steam header pressure regulating valve group 07 comprises a first on-off valve, a standby steam pressure regulating valve, a second on-off valve, and a third on-off valve connected in parallel with the first, pressure regulating valves, and the second on-off valves, which are installed in sequence along the steam flow direction.

[0036] On the auxiliary steam extraction pipe 6, a first auxiliary gate valve 1, an auxiliary check valve 2 and a second auxiliary gate valve 5 are installed in sequence along the steam flow direction;

[0037] The first auxiliary gate valve 1 is a fully intelligent, stoppable, electric gate valve designed to connect to an external DCS control system and rapidly shut off the steam supply in the event of pipeline overpressure or other emergencies. The first auxiliary gate valve 1 adjusts the auxiliary steam pressure in the auxiliary steam extraction pipeline 6 within a range of 0.588 to 0.785 MPa. The second auxiliary gate valve 5 is a manual gate valve used to isolate the gas supply during maintenance.

[0038] The auxiliary steam extraction pipe 6 is located between the auxiliary check valve 2 and the second auxiliary gate valve 5, and is also connected to the auxiliary emptying pipe 3 and the auxiliary drain pipe 4 through valves, which are used for pipe warming operations before commissioning; the auxiliary emptying pipe 3 and the auxiliary drain pipe 4 are both arranged on the auxiliary steam extraction pipe 6 between the auxiliary check valve 2 and the second auxiliary gate valve 5, the auxiliary emptying pipe 3 is arranged on the auxiliary steam extraction pipe 6 close to the auxiliary check valve 2 side, and the auxiliary drain pipe 4 is arranged on the auxiliary steam extraction pipe 6 close to the second auxiliary gate valve 5 side. Because liquid water may remain in the system during the pipeline installation process or when the unit is running, if the pipeline is not drained, a steam-water two-phase flow phenomenon may occur, causing the pipeline to vibrate violently; when encountering maintenance work, after the system is isolated, the emptying pipe can depressurize the system to protect the safety of the staff. The auxiliary emptying pipe 3 and the auxiliary drain pipe 4 are one of the equipment to ensure the safety of the system.

[0039] After the modification is complete, thermal control adjustments are required for this embodiment of the utility model. This involves performing thermal control logic configuration on the DCS (adding pressure and temperature measurement points as needed) and adding corresponding valves and pipelines to the corresponding screen. This allows operators to add the electric gate valve 1 by jogging, while also facilitating operation and monitoring of system operating parameters, controlling the auxiliary steam pressure between 0.588 and 0.785 MPa. Thus, while ensuring sufficient steam supply for the unit itself, the connecting pipe 05 installed between the auxiliary steam headers of each unit can provide sufficient steam to adjacent units.

[0040] The method of using the embodiment of the utility model is as follows:

[0041] S1, establish the plant steam system pressure;

[0042] S2, fully drain and warm the auxiliary steam extraction pipe 6;

[0043] S3, open the manual gate valve (second auxiliary gate valve 5);

[0044] S4, through DCS remote inching operation, slowly open the electric gate valve (first auxiliary gate valve 1), monitor the auxiliary steam pressure to keep it at 0.588~0.785MPa;

[0045] S5 ensures the auxiliary steam pressure is stable. At this time, adjacent units can also use this steam source through the connecting pipe 05, thus ensuring the safety of steam supply for the entire plant.

[0046] The above content is only an embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformation made using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, is included in the scope of patent protection of the present invention.

Claims

1. An auxiliary steam system operating under deep peak regulation conditions, comprising a reheat cold section (01) leading to a boiler reheater, the reheat cold section (01) being connected to a steam extraction pipeline (02), the steam extraction pipeline (02) being sequentially installed with a steam extraction isolation valve (03) and a steam extraction pressure regulating valve (04) along the steam flow direction, and then connected to a standby steam main pipe (06); a standby steam header pressure regulating valve group (07) being installed on the standby steam main pipe (06), the outlet of which is connected to a standby steam header (08); the standby steam header (08) being connected to the standby steam headers of other adjacent units via a connecting pipe (05); Its characteristics are: An auxiliary steam extraction pipeline (6) is further connected between the reheat cold section (01) and the standby steam main pipe (06), wherein the inlet end of the auxiliary steam extraction pipeline (6) is connected to the reheat cold section (01), and the outlet end is connected to the standby steam main pipe (06); A first auxiliary gate valve (1), an auxiliary check valve (2), and a second auxiliary gate valve (5) are sequentially installed on the auxiliary steam extraction pipeline (6) along the steam flow direction; The auxiliary steam extraction pipe (6) is located between the auxiliary check valve (2) and the second auxiliary gate valve (5), and is connected to the auxiliary exhaust pipe (3) and the auxiliary drain pipe (4) through valves, respectively, for pipe warming operations before commissioning; The first auxiliary gate valve (1) is a stoppable electric gate valve, which is used to connect to an external monitoring system and quickly cut off the steam source in the event of pipeline overpressure or other emergency conditions.

2. The auxiliary steam system operating under deep peak load regulation according to claim 1, characterized in that: The auxiliary exhaust pipe (3) and the auxiliary drain pipe (4) are both arranged on the auxiliary steam extraction pipe (6) between the auxiliary check valve (2) and the second auxiliary gate valve (5).

3. The auxiliary steam system operating under deep peak load regulation according to claim 2, characterized in that: The auxiliary exhaust pipe (3) is arranged on the auxiliary steam extraction pipe (6) near the auxiliary check valve (2); The auxiliary drain pipe (4) is arranged on the auxiliary steam extraction pipe (6) near the side of the second auxiliary gate valve (5).

4. The auxiliary steam system operating under deep peak load regulation according to claim 1, characterized in that: The first auxiliary gate valve (1) adjusts the auxiliary steam pressure in the auxiliary steam extraction pipeline (6) in a range of 0.588 to 0.785 MPa.

5. The auxiliary steam system operating under deep peak load regulation according to claim 1, characterized in that: The second auxiliary gate valve (5) is a manual gate valve used to isolate the gas source during maintenance.

6. The auxiliary steam system operating under deep peak load regulation according to claim 1, characterized in that: The first auxiliary gate valve (1) is connected to an external DCS control system.

7. The auxiliary steam system operating under deep peak load regulation according to claim 1, characterized in that: The inlet access point of the auxiliary steam extraction pipeline (6) is located on the reheat cold section (01), before the inlet access point of the steam extraction pipeline (02); the outlet access point of the auxiliary steam extraction pipeline (6) is located on the standby steam main pipe (06), before the standby steam manifold pressure regulating valve group (07).

8. The auxiliary steam system operating under deep peak load regulation according to claim 7, characterized in that: The standby steam header pressure regulating valve group (07) comprises a first switch valve, a standby steam pressure regulating valve and a second switch valve which are sequentially installed along the steam flow direction, and a third switch valve which is connected in parallel with the first switch valve, the pressure regulating valve and the second switch valve.

Images