CN116930649A - Load shedding test unit for double-suction reheating back pressure unit - Google Patents

Abstract

The invention discloses a load shedding test unit of a double-extraction reheating back pressure unit, which relates to the technical field of automatic control of thermal power units and comprises the following components: the main steam port of the boiler is connected with a bypass regulating valve through a pipeline, and the bypass regulating valve is connected to a sub-cooling system of the boiler through a pipeline; the high-pressure cylinder is provided with high-pressure regulating doors at two sides respectively, and the main steam port is connected with the high-pressure regulating doors; the two sides of the medium pressure cylinder are respectively provided with a medium pressure regulating door, a reheat steam port of the boiler and the medium pressure regulating door are connected with a high pressure deaerator, and four sections of steam extraction ports of the medium pressure cylinder, the high pressure deaerator, a water supply pump and the water inlet side of the boiler are sequentially connected; the low-pressure steam supply pipe is provided with a reheat-to-low pressure regulating valve between the reheat steam port and the low-pressure steam supply pipe, and the three-section steam extraction port of the medium pressure cylinder is connected with the low-pressure steam supply pipe; and a reheat-to-medium pressure regulating valve is arranged between the reheat steam port and the medium pressure steam supply pipe. The unit can quickly recover medium-pressure steam supply and low-pressure steam supply during load shedding.

Description

Load shedding test unit for double-suction reheating back pressure unit

Technical Field

The invention relates to the technical field of automatic control of thermal power units, in particular to a load shedding test unit of a double-suction reheat back pressure unit.

Background

In the related technology, along with the continuous increase of the specific gravity of the energy industry in modern life, how to supply steam for petrochemical enterprises with high quality, high efficiency and large flow is an important problem to be solved at present, however, the traditional thermal power enterprise owner adopts a steam turbine to extract steam to realize petrochemical steam supply or resident heat supply, the efficiency is generally lower, and once a machine set is stopped due to the occurrence of a problem, the stability of steam supply is affected, and serious economic loss is caused for downstream users.

The load shedding test is an important test for checking the dynamic characteristics of a unit regulating system, is also a test for the most severe unit, when an external network has faults and the power grid is disconnected, the boiler normally operates, and the steam turbine maintains the rated rotation speed to operate so that the external network line can be quickly recovered when normal, and is more important for a heating system, and because the load shedding instantaneous steam extraction valve is closed, low-pressure steam extraction is disconnected, so how to quickly recover medium-pressure steam and low-pressure steam supply during the load shedding period is important.

In summary, how to quickly recover the medium and low pressure steam supply during the load shedding period is a problem to be solved by those skilled in the art.

Disclosure of Invention

Therefore, the invention aims to provide a load shedding test unit of a double-extraction reheating back pressure unit, which can quickly recover medium-pressure steam supply and low-pressure steam supply during load shedding so as to ensure the safety and stability of downstream heat source users in abnormal conditions of the unit.

In order to achieve the above object, the present invention provides the following technical solutions:

a double-pumping reheating back pressure unit load shedding test unit comprises:

a main steam port of the boiler is connected with a bypass regulating valve through a pipeline, and the bypass regulating valve is connected to a sub-cooling system of the boiler through a pipeline;

the two sides of the high-pressure cylinder are respectively provided with a high-pressure regulating door, and the main steam port is connected with the high-pressure regulating door;

the two sides of the medium pressure cylinder are respectively provided with a medium pressure regulating door, and a reheat steam port of the boiler is connected with the medium pressure regulating door;

the four sections of steam extraction ports of the medium pressure cylinder, the high pressure deaerator, the water supply pump and the water inlet side of the boiler are connected in sequence;

the low-pressure steam supply pipe is provided with a reheat-to-low pressure regulating valve between the reheat steam port and the low-pressure steam supply pipe, and the three-section steam extraction port of the medium pressure cylinder is connected with the low-pressure steam supply pipe;

and a reheat to medium pressure regulating valve is arranged between the reheat steam port and the medium pressure steam supply pipe.

Preferably, four sections of steam extraction check valves and four sections of steam extraction gate valves are sequentially arranged between the four sections of steam extraction ports and the high-pressure deaerator;

the four-section steam extraction check valve is a pneumatic driving valve, and the four-section steam extraction gate valve is an electric driving valve.

Preferably, a three-section steam extraction check valve, a three-section steam extraction pressure control valve and a three-section steam extraction gate valve are sequentially arranged between the three-section steam extraction port and the low-pressure steam supply pipe;

the three-section steam extraction check valve is a pneumatic drive valve, the three-section steam extraction pressure control valve is a hydraulic drive valve, and the three-section steam extraction gate valve is an electric drive valve.

Preferably, the reheating-to-low pressure regulating valve comprises a reheating-to-low pressure steam supply pipeline check valve, a reheating-to-low pressure temperature and pressure reducer regulating valve and a reheating-to-low pressure temperature and pressure reducer temperature and pressure reducing water regulating valve which are connected in sequence;

the check valve of the reheating-to-low pressure steam supply pipeline is a pneumatic drive valve, and the regulating valve of the reheating-to-low pressure temperature-reduction pressure reducer and the regulating valve of the temperature-reduction water are hydraulic drive valves.

Preferably, a reheat low-pressure steam supply to deaerator gate valve is arranged between the reheat low-pressure temperature-reduction pressure reducer temperature-reduction water regulating valve and the high-pressure deaerator, and a reheat low-pressure steam supply pipeline gate valve is arranged between the reheat low-pressure temperature-reduction pressure reducer temperature-reduction water regulating valve and the low-pressure steam supply pipe;

and the valve of the reheating low-pressure steam supply pipeline and the valve of the reheating low-pressure steam supply deaerator are electrically driven valves.

Preferably, the reheating-to-medium pressure regulating valve comprises a reheating-to-medium pressure steam supply pipeline check valve, a reheating-to-medium pressure steam supply pipeline regulating valve and a reheating-to-medium pressure steam supply pipeline gate valve which are connected in sequence;

the reheating to medium pressure steam supply pipeline regulating valve is a hydraulic drive valve, the reheating to medium pressure steam supply pipeline check valve is a pneumatic drive valve, and the reheating to medium pressure steam supply pipeline gate valve is an electric drive valve.

Preferably, a bypass temperature-reducing water regulating valve is arranged between the bypass regulating valve and the sub-cooling system of the boiler;

the bypass regulating valve and the bypass temperature-reducing water regulating valve are both hydraulically driven valves.

Preferably, the high-pressure regulating gate and the medium-pressure regulating gate are both hydraulically driven valves.

Preferably, the high-pressure deaerator is respectively connected with two water supply pumps through pipelines, the water supply pumps are connected with a main water supply door of the boiler through a main pipe, and the main water supply door is connected with the water inlet side of the boiler through a pipeline;

the water supply pump is a pneumatic drive pump or an electric drive pump, and the main water supply valve is an electric drive valve.

Preferably, the control method of the bypass regulating valve includes:

judging the running condition of the unit;

if the unit normally operates, the bypass regulating valve is controlled to be in a fully closed state;

if the unit is in a load shedding running state, controlling the bypass regulating valve to open a preset opening, wherein the opening is a function value corresponding to the main steam flow of the boiler in the load shedding state;

and if the unit is in an automatic operation state, controlling the bypass regulating valve to open a preset opening, wherein the opening is a function value corresponding to the reheat steam flow of the boiler in the automatic operation state.

When the double-extraction reheating back pressure unit load shedding test unit provided by the invention is used, when the unit normally operates, the main steam port, the high-pressure regulating door and the high-pressure cylinder of the boiler are sequentially connected to supply steam to the high-pressure cylinder of the steam turbine. The reheat steam port, the intermediate pressure regulating door and the intermediate pressure cylinder of the boiler are sequentially connected to supply steam to the intermediate pressure cylinder of the steam turbine. And the low-pressure steam supply pipe can be supplied with steam through three sections of steam extraction of the medium-pressure cylinder, and the medium-pressure steam supply pipe is supplied with steam through reheat steam of the boiler. In addition, four sections of steam extraction ports, a high-pressure deaerator, a water supply pump and the water inlet side of the boiler of the medium-pressure cylinder are sequentially connected, so that the water circulation and the normal operation of the boiler are realized.

When the unit fails, the low-pressure steam supply pipe and the medium-pressure steam supply pipe can be respectively supplied with steam through reheat steam of the boiler, so that the stability of the system is improved, and the stable operation of a downstream user is ensured. And when the unit fails, the bypass regulating valve can carry out bypass regulation on the pressure of the boiler so as to ensure that the pressure of the steam supply source is stable under any working condition, and the unit can be automatically put into use during load shedding without manual intervention of operators, so that the emergency treatment capacity under the accident condition is improved.

The system can effectively utilize the waste heat in the high-temperature smoke exhaust, improve the power generation efficiency, reduce the energy loss and reduce the energy consumption, thereby realizing high efficiency and energy conservation. Moreover, the system can be suitable for various industrial applications, such as the fields of thermal power plants, metallurgy, petrochemical industry, chemical industry and the like, and can ensure the safety and stability of downstream heat source users in the case of abnormal conditions of units.

In summary, the load shedding test unit of the double-extraction reheating back pressure unit provided by the invention can quickly recover medium-pressure steam supply and low-pressure steam supply during load shedding, so that safety and stability of downstream heat source users are ensured in abnormal conditions of the unit.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic structural diagram of a load shedding test unit of a double-suction reheat back pressure unit provided by the invention;

fig. 2 is a schematic flow chart of a control method of a bypass regulating valve provided by the invention.

In fig. 1-2:

the boiler is characterized in that the boiler is 1, the high-pressure cylinder is 2, the medium-pressure cylinder is 3, the high-pressure deaerator is 4, the water supply pump is 5, the main water supply door is 6, the bypass regulating valve is 7, the bypass temperature-reducing water regulating valve is 8, the high-pressure regulating valve is 9, the medium-pressure regulating valve is 10, the four-section steam extraction check valve is 11, the four-section steam extraction gate valve is 12, the three-section steam extraction check valve is 13, the three-section steam extraction pressure control valve is 14, the three-section steam extraction gate valve is 15, the reheating to low-pressure steam supply pipeline check valve is 16, the reheating to low-pressure temperature-reducing pressure-reducing regulating valve is 17, the reheating to low-pressure temperature-reducing pressure-reducing valve is 18, the reheating to low-pressure-reducing water supply valve is 19, the reheating to medium-pressure steam supply pipeline check valve is 20, the reheating to medium-pressure steam supply pipeline check valve is 21, the reheating to medium-pressure steam supply pipeline regulating valve is 22, the reheating to medium-pressure steam supply pipeline gate valve is 23, the reheating to the medium-pressure supply pipeline gate valve is 24, the low pressure supply pipeline valve is 24, and the low pressure supply pipeline is 25.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The core of the invention is to provide a load dump test unit of a double-extraction reheating back pressure unit, which can quickly recover medium-pressure steam supply and low-pressure steam supply during load dump so as to ensure the safety and stability of downstream heat source users in abnormal conditions of the unit.

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of a load shedding test unit of a double-pumping reheat back pressure unit provided by the invention; fig. 2 is a schematic flow chart of a control method of a bypass regulating valve provided by the invention.

The embodiment provides a load shedding test unit of a double-suction reheat back pressure unit, which comprises:

the boiler 1, the main steam port of the boiler 1 is connected with the bypass regulating valve 7 through a pipeline, and the bypass regulating valve 7 is connected to a sub-cooling system of the boiler 1 through a pipeline;

the high-pressure cylinder 2, the both sides of the high-pressure cylinder 2 are equipped with the high-pressure control door 9 separately, the main steam port is connected with high-pressure control door 9;

the middle pressure cylinder 3, there are medium pressure regulating doors 10 on both sides of the middle pressure cylinder 3 separately, reheat steam of the boiler 1. Steam port and medium pressure regulating door 10 are connected;

the four sections of steam extraction ports of the high-pressure deaerator 4 and the medium-pressure cylinder 3, the high-pressure deaerator 4, the water supply pump 5 and the water inlet side of the boiler 1 are connected in sequence;

a reheat to low pressure regulating valve is arranged between the reheat steam port and the low pressure steam supply pipe 24, and the three-section steam extraction port of the medium pressure cylinder 3 is connected with the low pressure steam supply pipe 24;

a reheat to intermediate pressure regulating valve is arranged between the intermediate pressure steam supply pipe 25 and the reheat steam port and the intermediate pressure steam supply pipe 25.

The high-pressure cylinder 2 and the medium-pressure cylinder 3 of the steam turbine are supplied with steam heat energy from the boiler 1, the steam inflow of the steam turbine is controlled through the high-pressure regulating gate 9 and the medium-pressure regulating gate 10, and the main steam pressure is controlled through the bypass regulating valve 7. The bypass regulating valve 7 is pre-opened to a certain opening degree when the load is thrown and is automatically put into an automatic state, and the regulated quantity of the bypass regulating valve 7 is switched from a main steam pressure signal to a reheat steam pressure signal when the unit is started.

And, the unit heating system includes a medium-pressure steam supply pipe 25 and a low-pressure steam supply pipe 24. Wherein, the medium pressure steam supply pipe 25 controls the medium pressure steam supply pressure by the reheat-to-medium pressure regulating valve of the boiler. The low-pressure steam supply pipe 24 supplies steam by two modes of three-section steam extraction and supply and reheat steam of the middle pressure cylinder 3 of the steam turbine after passing through a temperature and pressure reducer.

When the double-extraction reheating back pressure unit load shedding test unit provided by the invention is used, when the unit normally operates, the main steam port, the high-pressure regulating door 9 and the high-pressure cylinder 2 of the boiler 1 are sequentially connected to supply steam to the high-pressure cylinder 2 of the steam turbine. The reheat steam port, the intermediate pressure regulating gate 10 and the intermediate pressure cylinder 3 of the boiler 1 are connected in order to supply steam to the intermediate pressure cylinder 3 of the steam turbine. And, can supply steam for the low pressure steam supply pipe 24 through the three-stage extraction steam of the medium pressure cylinder 3, supply steam for the medium pressure steam supply pipe 25 through the reheat steam of the boiler 1. In addition, four sections of steam extraction ports of the medium pressure cylinder 3, the high pressure deaerator 4, the water feeding pump 5 and the water inlet side of the boiler 1 are sequentially connected, so that the water circulation and normal operation of the boiler 1 are realized.

When the unit fails, the low-pressure steam supply pipe 24 and the medium-pressure steam supply pipe 25 can be respectively supplied with the reheat steam of the boiler 1, so that the stability of the system is improved, and the stable operation of a downstream user is ensured. Moreover, when the unit fails, the bypass regulating valve 7 can carry out bypass regulation on the pressure of the boiler 1 so as to ensure the pressure stability of the steam supply source under any working condition, and the unit can be automatically put into use during load shedding without manual intervention of operators, so that the emergency handling capacity under the accident condition is improved.

The system can effectively utilize the waste heat in the high-temperature smoke exhaust, improve the power generation efficiency, reduce the energy loss and reduce the energy consumption, thereby realizing high efficiency and energy conservation. Moreover, the system can be suitable for various industrial applications, such as the fields of thermal power plants, metallurgy, petrochemical industry, chemical industry and the like, and can ensure the safety and stability of downstream heat source users in the case of abnormal conditions of units.

In summary, the load shedding test unit of the double-extraction reheating back pressure unit provided by the invention can quickly recover medium-pressure steam supply and low-pressure steam supply during load shedding, so that safety and stability of downstream heat source users are ensured in abnormal conditions of the unit.

On the basis of the above embodiment, it is preferable that four sections of steam extraction check valves 11 and four sections of steam extraction gate valves 12 are sequentially arranged between the four sections of steam extraction ports and the high-pressure deaerator 4; the four-section steam extraction check valve 11 is a pneumatic drive valve, and the four-section steam extraction gate valve 12 is an electric drive valve.

That is, the four sections of steam extraction of the medium pressure cylinder 3 are connected with the four sections of steam extraction check valves 11 through pipelines, the four sections of steam extraction check valves 11 are connected with the four sections of steam extraction gate valves 12 through pipelines, and the four sections of steam extraction gate valves 12 are connected with the high pressure deaerator 4 through pipelines. In addition, the four-section steam extraction check valve 11 is controlled in a pneumatic driving mode, and has the advantages of being quick in response and low in cost. The four-section steam extraction gate valve 12 is controlled in an electric driving mode, so that flushing of an adjusting door can be reduced, and an isolation effect is achieved.

Preferably, a three-section steam extraction check valve 13, a three-section steam extraction pressure control valve 14 and a three-section steam extraction gate valve 15 are sequentially arranged between the three-section steam extraction port and the low-pressure steam supply pipe 24; the three-section steam extraction check valve 13 is a pneumatic drive valve, the three-section steam extraction pressure control valve 14 is a hydraulic drive valve, and the three-section steam extraction gate valve 15 is an electric drive valve.

The steam turbine is a double-extraction back pressure machine, three sections of exhaust steam of a middle pressure cylinder 3 of the steam turbine are connected with three sections of steam extraction check valves 13 through pipelines, the three sections of steam extraction check valves 13 are connected with three sections of steam extraction pressure control valves 14 through pipelines, the three sections of steam extraction pressure control valves 14 are connected with three sections of steam extraction gate valves 15 through pipelines, and the three sections of steam extraction gate valves 15 are connected to a low-pressure steam supply pipe 24 through pipelines. The three-section steam extraction check valve 13 is controlled in a pneumatic driving mode, and has the advantages of being quick in reaction and low in cost. The three-section steam extraction pressure control valve 14 is controlled in a hydraulic driving mode, and has the advantages of quick response and accurate control. The three-section steam extraction gate valve 15 is controlled in an electric driving mode, so that flushing of an adjusting door can be reduced, and an isolation effect is achieved.

Preferably, the reheating-to-low pressure regulating valve comprises a reheating-to-low pressure steam supply pipeline check valve 16, a reheating-to-low pressure temperature-reduction pressure reducer regulating valve 17 and a reheating-to-low pressure temperature-reduction pressure reducer temperature-reduction water regulating valve 18 which are connected in sequence; the check valve 16 of the reheating-to-low pressure steam supply pipeline is a pneumatic driving valve, and the regulating valve 17 of the reheating-to-low pressure temperature-reduction pressure reducer and the regulating valve 18 of the reheating-to-low pressure temperature-reduction pressure reducer are hydraulic driving valves.

Preferably, a reheat low-pressure steam supply to deaerator gate valve 20 is arranged between the reheat low-pressure temperature-reduction pressure reducer temperature-reduction water regulating valve 18 and the high-pressure deaerator 4, and a reheat low-pressure steam supply pipeline gate valve 19 is arranged between the reheat low-pressure temperature-reduction pressure reducer temperature-reduction water regulating valve 18 and the low-pressure steam supply pipe 24; the reheat-to-low pressure steam supply pipeline gate valve 19 and the reheat-low pressure steam supply-to-deaerator gate valve 20 are both electrically driven valves.

The reheater outlet of the boiler 1 is connected with a check valve 16 of the reheating low-pressure steam supply pipeline through a pipeline, the check valve 16 of the reheating low-pressure steam supply pipeline is connected with a regulating valve 17 of the reheating low-pressure temperature-reduction pressure reducer through a pipeline, the regulating valve 17 of the reheating low-pressure-reduction pressure reducer is connected with a gate valve 19 of the reheating low-pressure steam supply pipeline through a pipeline, and the gate valve 19 of the reheating low-pressure steam supply pipeline is connected with a low-pressure steam supply pipeline 24 through a pipeline; the reheat to low pressure temperature and pressure reducer regulating valve 17 is connected with a reheat to low pressure temperature and pressure reducer water regulating valve 18 through a pipeline, the reheat to low pressure temperature and pressure reducer regulating valve 18 is connected with a reheat to low pressure steam supply pipeline gate valve 19 through a pipeline, and the reheat to low pressure steam supply pipeline gate valve 19 is connected with the high pressure deaerator 4 through a pipeline.

The medium-pressure regulating gate 10, the regulating valve 17 of the reheating-to-low-pressure temperature-reduction pressure reducer and the temperature-reduction water regulating valve 18 of the reheating-to-low-pressure temperature-reduction pressure reducer of the steam turbine are controlled in a hydraulic driving mode, and the hydraulic driving type low-pressure temperature-reduction pressure reducer has the advantages of being rapid in reaction and accurate in control. The reheating to low pressure steam supply pipeline gate valve 19, the reheating low pressure steam supply to deaerator gate valve 20 and the reheating to medium pressure steam supply pipeline gate valve 23 are all controlled by adopting an electric driving mode, and the electric driving control mode has the advantages of reducing flushing of an adjusting gate and playing an isolating effect on the adjusting gate.

Preferably, the reheat-to-medium pressure regulating valve comprises a reheat-to-medium pressure steam supply pipe 25 check valve 21, a reheat-to-medium pressure steam supply pipe regulating valve 22 and a reheat-to-medium pressure steam supply pipe gate valve 23 which are connected in sequence; the reheat-to-medium pressure steam supply pipeline regulating valve 22 is a hydraulic drive valve, the reheat-to-medium pressure steam supply pipeline check valve 21 is a pneumatic drive valve, and the reheat-to-medium pressure steam supply pipeline gate valve 23 is an electric drive valve.

That is, the reheater outlet of the boiler 1 is connected to the reheat to intermediate pressure steam supply pipe 25 pipe check valve 21 through a pipe, the reheat to intermediate pressure steam supply pipe 25 pipe check valve 21 is connected to the reheat to intermediate pressure steam supply pipe regulating valve 22 through a pipe, the reheat to intermediate pressure steam supply pipe regulating valve 22 is connected to the reheat to intermediate pressure steam supply pipe gate valve 23 through a pipe, and the reheat to intermediate pressure steam supply pipe gate valve 23 is connected to the intermediate pressure steam supply pipe 25 through a pipe. The check valve 16 for reheating to the low-pressure steam supply pipeline and the check valve 21 for reheating to the medium-pressure steam supply pipeline are controlled in a pneumatic driving mode, and have the advantages of faster reaction and lower cost.

On the basis of the above embodiment, it is preferable that a bypass desuperheating water regulating valve 8 is provided between the bypass regulating valve 7 and the sub-cooling system of the boiler 1; the bypass regulating valve 7 and the bypass temperature-reducing water regulating valve 8 are both hydraulically driven valves.

The main steam port of the boiler 1 is connected to a bypass control valve 7 through a pipe, the bypass control valve 7 is connected to the sub-cooling system of the boiler 1 through a pipe, and a bypass desuperheating water control valve 8 is connected to the bypass control valve 7 through a pipe. The bypass regulating valve 7 and the bypass temperature-reducing water regulating valve 8 are controlled in a hydraulic driving mode, and the hydraulic control valve has the advantages of being quick in response and accurate in control. The bypass control valve 7 has a capacity of 100% bmcr (Boiler maximum continuous rating, maximum continuous evaporation capacity of boiler) and is mainly configured to meet the maximum output under the conditions of steam parameters and furnace safety, so that the bypass control valve 7 has a quick-opening function at high pressure.

Preferably, the high-pressure regulating gate 9 and the medium-pressure regulating gate 10 are all hydraulically driven valves, wherein the regulating gates are controlled in a hydraulically driven mode, and the hydraulic control valve has the advantages of quick response and accurate control.

Preferably, the high-pressure deaerator 4 is respectively connected with two water feed pumps 5 through pipelines, the water feed pumps 5 are connected with a main water feed door 6 of the boiler 1 through a main pipe, and the main water feed door 6 is connected with the water inlet side of the boiler 1 through a pipeline; the water supply pump 5 is a pneumatic drive pump or an electric drive pump, and the main water supply valve 6 is an electric drive valve. Therefore, the driving modes of the water feed pump 5 and the main water feed gate 6 can be determined according to the actual conditions and the actual demands in the actual application process.

Preferably, the control method of the bypass regulating valve 7, the flow chart of which is shown in fig. 2, includes:

judging the running condition of the unit;

if the unit normally operates, the bypass regulating valve 7 is controlled to be in a fully closed state;

if the unit is in a load shedding running state, controlling the bypass regulating valve 7 to open a preset opening, wherein the opening is a function value corresponding to the main steam flow of the boiler 1 in the load shedding state;

if the unit is in an automatic operation state, the bypass regulating valve 7 is controlled to open a preset opening degree, wherein the opening degree is a function value corresponding to the reheat steam flow of the boiler 1 in the automatic operation state.

It should be noted that, before the load shedding test of the unit, the overspeed protection test of the steam turbine should be completed, the activity test of the high-pressure main valve and the medium-pressure main valve is completed, and the interlocking start test of the alternating-current lubricating oil pump and the direct-current lubricating oil pump is completed, so as to ensure that the test is qualified and the action is correct.

The power generator outlet breaker switch is manually disconnected, the power generator is disconnected, and a load shedding signal of the steam turbine is triggered, at the moment, the rotating speed of the steam turbine can be rapidly increased, so that the stable operation of the steam turbine is maintained.

When the unit normally operates, the bypass regulating valve 7 is in a fully closed state so as to ensure the efficiency of the unit, after the load shedding signal is triggered, the high-pressure bypass regulating valve 7 is pre-opened by a certain opening degree so as to ensure that the main steam pressure is not overrun, the pre-opened opening degree is a function value corresponding to the current main steam flow when the load shedding is performed, the function value can be set according to the actual condition of the unit, the following description is given by the condition of a double-extraction reheat back pressure unit at the first stage of a factory in China, and the setting function is shown in the following table 1:

TABLE 1

The bypass regulating valve 7 is automatically put into an automatic state, and the regulated quantity is switched from a main steam pressure signal to a reheat steam pressure signal when the unit is started so as to maintain the stability of steam supply pressure. The bypass regulating valve 7 is set to reheat steam pressure during load shedding, and the upper limit of the set value is 6MPa.

The bypass temperature-reducing water regulating valve 8 is pre-opened to 50 percent and is automatically put into an automatic state, and the set value is 380 ℃.

The regulating valve 17 of the reheated low-pressure temperature-reducing pressure reducer is automatically put into an automatic state, the set value is the low-pressure steam supply pressure value during load shedding, the regulating valve 17 of the reheated low-pressure temperature-reducing pressure reducer is regulated on the basis of the current valve position, so that the stability of the low-pressure steam supply pressure is ensured, and the minimum opening is 8%.

The water temperature reducing regulating valve 18 of the low-pressure temperature and pressure reducer is pre-opened to 15 percent, and the automatic state is automatically put into operation, and the set value is the low-pressure steam supply temperature during load shedding.

The main control of the boiler 1 is switched to a manual mode, the output value is 50% of the total water supply flow during load shedding, and the minimum flow threshold is set to be 400t/h.

The feed pump 5 controls the rotation speed of the pneumatic feed pump 5 or the opening of the scoop tube of the electric feed pump 5 according to the output value of the main control of the boiler 1 as a set value.

All coal feeders are automatically put into an automatic state, and a fuel master control is automatically put into the automatic state, the coal feeding amount of each coal feeder is evenly distributed to each coal feeder by the fuel master control, the fuel master control is given by the function value of the master control of the boiler 1, and the master control output function of the fuel master control corresponding to the master control output of the boiler 1 is shown in the following table 2:

TABLE 2

Boiler main control output (t/h)	Fuel master control output (t/h)
		0	20
300	20
		360	30
500	73.53
		800	119.4
1000	149.3
		1200	179

If the middle point temperature is in an automatic state, the command output of the middle point temperature is locked for 35 seconds, and frequent adjustment of the coal quantity and the water supply quantity during load shedding is eliminated.

The interlocking opens the reheat low pressure steam supply to the deaerator gate valve 20 to ensure a substantial drop in deaerator pressure during load shedding, resulting in cavitation of the feed pump 5.

The auxiliary steam is preheated to 15% by a shaft seal steam supply pressure regulating valve, and the auxiliary steam is automatically put into an automatic state, and the set value is the shaft seal steam main pipe pressure during load shedding.

The safety measures and precautions in the load shedding test process comprise:

the high-pressure bypass system has no water impact, and the support hanger and the pipeline have no abnormality;

after load shedding, OPC acts normally, and after the rotation speed of the unit is stable, the rotation speed is recorded to be increased to the highest rotation speed;

because the pressure of the high-pressure deaerator 4 possibly fluctuates after load shedding, false water level is caused, and the water level control of the high-pressure deaerator 4 needs to be closely paid attention to;

tripping of the steam turbine, and quick closing of valves such as a main steam valve, a regulating valve, a three-section steam extraction pressure control valve and the like;

checking the change conditions of vibration, expansion difference, radial bearing, thrust bearing temperature, axial displacement, exhaust steam temperature and the like of the unit;

confirming that the high-pressure bypass regulating valve acts correctly and the temperature reduction water is regulated normally;

checking that each auxiliary machine runs normally without tripping;

and (5) checking the opening condition of each drain valve of the steam turbine body and the steam extraction pipeline.

Load shedding test judges success standard: the steam turbine regulating system has good dynamic characteristics, overspeed protection is not operated, all interlocking devices are automatically put into operation, the regulating effect is good, the dynamic process is rapid and stable, the low-pressure steam supply pressure is stable, and the medium-pressure steam supply pressure is stable.

Compared with other types of generator sets, the double-extraction reheating back pressure unit has the following advantages:

1. high efficiency and energy saving: the double-extraction reheating back pressure unit adopts a reheating repressing energy-saving circulation technology, so that the waste heat in high-temperature smoke exhaust can be effectively utilized, the power generation efficiency is improved, the energy loss is reduced, and the energy consumption is reduced, thereby realizing high efficiency and energy conservation.

2. The heat efficiency is high: the double-extraction reheating back pressure unit has high heat efficiency, can fully exert the heat power of the unit in the power generation process, and reduces heat loss. For example, during high temperature seasons, the output of the unit is increased, and meanwhile, the use efficiency of cooling water in the unit is also increased, so that the thermal efficiency is further improved.

3. The stability is good: when the double-extraction reheating back pressure unit operates, steam is supplied to the low-pressure pipeline through unit steam extraction, steam is supplied to the medium-pressure pipeline through the reheater, and when the unit fails, the low-pressure and medium-pressure pipeline is supplied through the reheater temperature and pressure reducer, so that the stability of the system is improved, and the stable operation of a downstream user is ensured.

4. The adaptability is strong: the double-extraction reheating back pressure unit has strong adaptability and can be suitable for various industrial applications, such as the fields of thermal power plants, metallurgy, petrochemical industry, chemical industry and the like. In addition, under the trend of increasing energy crisis and environmental protection pressure, the double-pumping reheating back pressure unit is used as a high-efficiency energy-saving and environment-friendly unit type, and is widely applied and popularized.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. Any combination of all the embodiments provided in the present invention is within the protection scope of the present invention, and will not be described herein.

The load shedding test unit of the double-suction reheat back pressure unit provided by the invention is described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims (10)

1. The utility model provides a two take out reheat backpressure unit load shedding test unit which characterized in that includes:

a boiler (1), the main steam port of the boiler (1) is connected with a bypass regulating valve (7) through a pipeline, and the bypass regulating valve (7) is connected to a sub-cooling system of the boiler (1) through a pipeline;

the high-pressure cylinder (2), two sides of the high-pressure cylinder (2) are respectively provided with a high-pressure regulating door (9), and the main steam port is connected with the high-pressure regulating door (9);

the system comprises a medium pressure cylinder (3), wherein medium pressure regulating doors (10) are respectively arranged on two sides of the medium pressure cylinder (3), and a reheat steam port of the boiler (1) is connected with the medium pressure regulating doors (10);

the four sections of steam extraction ports of the medium pressure cylinder (3), the high pressure deaerator (4), a water supply pump (5) and the water inlet side of the boiler (1) are connected in sequence;

a low-pressure steam supply pipe (24), wherein a reheat-to-low pressure regulating valve is arranged between the reheat steam port and the low-pressure steam supply pipe (24), and the three-section steam extraction port of the medium pressure cylinder (3) is connected with the low-pressure steam supply pipe (24);

and a reheating to medium pressure regulating valve is arranged between the reheating steam port and the medium pressure steam supply pipe (25).

2. The double-extraction reheating backpressure unit load shedding test unit according to claim 1, wherein four sections of steam extraction check valves (11) and four sections of steam extraction gate valves (12) are sequentially arranged between the four sections of steam extraction ports and the high-pressure deaerator (4);

the four-section steam extraction check valve (11) is a pneumatic driving valve, and the four-section steam extraction gate valve (12) is an electric driving valve.

3. The double-extraction reheating backpressure unit load shedding test unit according to claim 1, wherein a three-section extraction check valve (13), a three-section extraction pressure control valve (14) and a three-section extraction gate valve (15) are sequentially arranged between the three-section extraction port and the low-pressure steam supply pipe (24);

the three-section steam extraction check valve (13) is a pneumatic drive valve, the three-section steam extraction pressure control valve (14) is a hydraulic drive valve, and the three-section steam extraction gate valve (15) is an electric drive valve.

4. The double-pumping reheating back pressure unit load shedding test unit according to claim 1, wherein the reheating-to-low pressure regulating valve comprises a reheating-to-low pressure steam supply pipeline check valve (16), a reheating-to-low pressure temperature and pressure reducer regulating valve (17) and a reheating-to-low pressure temperature and pressure reducer temperature and pressure reducing water regulating valve (18) which are connected in sequence;

the check valve (16) of the reheating-to-low pressure steam supply pipeline is a pneumatic driving valve, and the regulating valve (17) of the reheating-to-low pressure temperature-reducing pressure reducer and the regulating valve (18) of the reheating-to-low pressure temperature-reducing pressure reducer are both hydraulic driving valves.

5. The double-pumping reheating back pressure unit load shedding test unit according to claim 4, wherein a reheating low-pressure steam supply to deaerator gate valve (20) is arranged between a reheating low-pressure temperature and pressure reducer temperature and pressure reducing water regulating valve (18) and the high-pressure deaerator (4), and a reheating low-pressure steam supply pipeline gate valve (19) is arranged between the reheating low-pressure temperature and pressure reducer temperature and pressure reducing water regulating valve (18) and the low-pressure steam supply pipe (24);

the reheating-to-low-pressure steam supply pipeline gate valve (19) and the reheating-to-low-pressure steam supply-to-deaerator gate valve (20) are electric driving valves.

6. The double-pumping reheat back pressure unit load shedding test unit as defined in any one of claims 1 to 5, wherein the reheat-to-medium pressure regulating valve comprises a reheat-to-medium pressure steam supply pipe check valve (21), a reheat-to-medium pressure steam supply pipe regulating valve (22) and a reheat-to-medium pressure steam supply pipe gate valve (23) which are sequentially connected;

the reheating to medium pressure steam supply pipeline regulating valve (22) is a hydraulic drive valve, the reheating to medium pressure steam supply pipeline check valve (21) is a pneumatic drive valve, and the reheating to medium pressure steam supply pipeline gate valve (23) is an electric drive valve.

7. The double-extraction reheating back pressure unit load shedding test unit according to any one of claims 1-5, characterized in that a bypass desuperheating water regulating valve (8) is arranged between the bypass regulating valve (7) and the sub-cooling system of the boiler (1);

the bypass regulating valve (7) and the bypass temperature-reducing water regulating valve (8) are hydraulically driven valves.

8. The double-suction reheat back pressure unit load shedding test unit according to any one of claims 1 to 5, wherein the high pressure regulating gate (9) and the medium pressure regulating gate (10) are both hydraulically driven valves.

9. The double-pumping reheating backpressure unit load shedding test unit according to any one of claims 1 to 5, wherein the high-pressure deaerator (4) is respectively connected with two water feeding pumps (5) through pipelines, the water feeding pumps (5) are connected with a main water feeding door (6) of the boiler (1) through a main pipe, and the main water feeding door (6) is connected with the water inlet side of the boiler (1) through a pipeline;

the water supply pump (5) is a pneumatic drive pump or an electric drive pump, and the main water supply valve (6) is an electric drive valve.

10. The double-suction reheat back pressure unit load rejection test unit according to any one of claims 1 to 5, characterized in that the control method of the bypass regulating valve (7) includes:

judging the running condition of the unit;

if the unit normally operates, the bypass regulating valve (7) is controlled to be in a fully closed state;

if the unit is in a load shedding running state, controlling the bypass regulating valve (7) to open a preset opening, wherein the opening is a function value corresponding to the main steam flow of the boiler (1) in the load shedding state;

and if the unit is in an automatic operation state, controlling the bypass regulating valve (7) to open a preset opening, wherein the opening is a function value corresponding to the reheat steam flow of the boiler (1) in the automatic operation state.