JP4197667B2 - Preparation method before boiler ignition - Google Patents

Description

  The present invention relates to a preparation method before boiler ignition when a power plant is started.

  This type of power plant is generally composed of a boiler, a turbine, a generator, etc., and burns fuel such as heavy oil or LNG (liquefied natural gas) in the boiler to produce high-temperature and high-pressure steam, which is then used as turbine blades. It is sprayed on a car to rotate the turbine at high speed, and electricity is generated by a generator connected to the rotating shaft of the turbine.

  In order to ignite (start up) this type of boiler at the time of starting the plant, it is necessary to satisfy some requirements. Specifically, (1) The boiler is filled with (predetermined amount of water) and (2) the boiler is filled with fresh air for burning fuel, (3) It is necessary to satisfy each requirement such that the inside of the boiler can be burned safely.

  Usually, in order to satisfy the requirements (1) to (3) above, (1) a water supply process (a process for supplying water to piping in a boiler) and (2) a ventilation process (a predetermined amount of air in the boiler). And (3) purge in the boiler (furnace) and fuel leak test process are executed before the ignition of the boiler.

  By the way, the processes (2) and (3) have been conventionally performed after the process (1) is completed. In the processes (2) and (3), air is allowed to flow into the boiler. In this case, the piping in the boiler is cooled by being exposed to outside air, and temporarily (1) Even if the processes (2) and (3) are executed during the water supply process, the piping is cooled and the water pressure is prevented from rising, and as a result, the end time of the water supply process is not delayed. In addition, the reason is that there is a prediction that the water temperature will be greatly lowered than expected due to cooling of the piping, and that the water temperature rise time due to boiler ignition in the next process will be delayed.

  For the above reasons, conventionally, since the preparations for boiler ignition are executed in series in the order (1) to (3), the time required from the start of boiler ignition preparation to its completion is determined by each of the above processes. Was equal to the sum of the execution times of

  The present invention reduces the cost required for boiler ignition when starting a power plant by shortening the time required for preparation before boiler ignition by efficiently performing each process before the boiler ignition. Let it be an issue.

The preparation method before the ignition of the boiler according to the present invention includes a water supply process for supplying water into the boiler until a predetermined pressure and a predetermined flow rate at the time of starting the power plant, and air until the inside of the boiler is replaced with fresh air. A pre-ignition method before boiler ignition, including a ventilation process to be circulated and a purge and fuel leak test process in the boiler that performs purge and fuel leak check in the boiler , wherein water supplied into the boiler in the water supply process When there predetermined pressure in ing, even if the water supply process is not completed, the start the ventilation process, after the ventilating process is finished, to start the boiler purge and fuel leak test process Features.

According to the preparation method before the boiler ignition , when a predetermined condition is established during the water supply to the boiler, even if the water supply process is not completed, the ventilation system (for example, a forced air blower) is activated, air into the boiler Ru flowed (flow). Then, a predetermined time (e.g., conventional ventilation process execution time) has elapsed, the purge and leak check rows song Me of the fuel in the boiler, as in the prior art, other processes (ventilation process until the water supply process is completed, the boiler The internal purge and fuel leak test process) is not waited for, and the preparation time before boiler ignition can be shortened.

  The “purging in the boiler” refers to a process in which unburned components (unburned materials) in the furnace (boiler) are blown away by wind power such as a forced air blower.

  The “fuel leak test” is a process for checking whether or not there is a leak in the fuel system (for example, leakage from the burner valve into the furnace). Specifically, a fuel pump such as light oil is started, fuel is sealed between a predetermined shutoff valve and a closed burner valve for a certain period of time, and the presence or absence of pressure drop is checked.

The conditions for starting the ventilation process are various factors (water supply amount, temperature, pressure, air inflow amount, etc.) so that the influence on the water pressure rise is minimized even if the ventilation system is activated and air is introduced. and it is to be determined in consideration of, at present, in the water supply process, the water pressure in the boiler is and effectively realized simply that the case, which was found to be stable state I can say that.

Specifically, the pressure in the pipe is checked by a water pressure gauge (generally permanently installed) provided at a predetermined position of the pipe in the boiler, and this is a value within a predetermined range (for example, 23.63 MPa to 24.61 MPa). everyone be a stable state a calm state. That is, in the preparation method before boiler ignition according to the present invention, the predetermined pressure may be 23.63 MPa to 24.61 MPa.

  The preparation method before boiler ignition according to the present invention is not intended for a specific power plant or operation mode for its application, but is preferably used in DSS (Daily Start and Stop) operation in a thermal power plant. It is.

  The reason is that there is little variation in the boiler water pressure rise time in the DSS operation, and the boiler water temperature is kept high so that the influence on the boiler in the present invention is minimized.

  As described above, according to the present invention, the time required for preparation before boiler ignition at the time of starting the power plant can be shortened, so that the motive energy can be saved and the cost can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the overall configuration of the power plant according to the present embodiment. In the power plant shown in FIG. 1, 1 is a boiler that burns fuel to generate high-temperature and high-pressure steam, 2 is an FDF (push-in ventilator) that supplies air into the boiler 1, 3 is light oil from a fuel tank (not shown), A fuel pump that supplies fuel such as heavy oil, 4 is a burner that burns the supplied fuel, 5 is a turbine that rotates at high speed when high-temperature and high-pressure steam generated in the boiler 1 is blown, and 6 is connected to the turbine 5. A generator that generates electric power by rotational force, 7 is a condenser that cools high-temperature and high-pressure steam that rotates the turbine 6 using seawater, and 8 is a BFP that supplies water cooled by the condenser 7 to the boiler 1 again. (Water supply pump).

  The power plant according to the present embodiment having the above-described configuration is a general thermal power plant, and is not characterized by the configuration or the power generation system during operation (startup). The power plant according to the present embodiment of the present invention is characterized by a preparation procedure (method) before boiler ignition in the plant start-up.

  By the way, in general, in order to be able to ignite (start) the boiler, (1) a predetermined amount of water is sealed in the (pipe) of the boiler at a predetermined pressure (end of the water supply process), (2) the boiler The inside is filled with fresh air (end of ventilation process), (3) No unburned components (unburned material) of fuel in the boiler, and no fuel leakage (leak) has occurred ( All conditions of the purge in the boiler and the end of the fuel leak test process) must be satisfied.

  The preparation before the conventional boiler ignition performed these processes in order of said (1)-(3). Therefore, for example, if the required times of the water supply process, the ventilation process, the purge in the boiler, and the fuel leak test process are 38 minutes, 5 minutes, and 7 minutes, respectively, the preparation before the boiler ignition takes 50 minutes.

  The present invention adopts a new method of performing a ventilation process and purge in a boiler and a fuel leak test process in parallel with a water supply process that normally requires the longest time, so that the boiler ignition is compared with the conventional method. It has the feature that the previous preparation time can be shortened.

  Such feature points will be described below with reference to the flowchart of FIG. 3 with reference to FIG.

  First, the BFP 8 is activated and water is supplied from the condenser 7 into the piping of the boiler 1 (step S101). In this state, the steam control valve 21 that connects the boiler 1 and the turbine 5 is closed, and the supplied water does not pass through the turbine 5 via the pipe 22 in the boiler 1. It returns to the condenser 7 from another system which is not shown in figure, and it will be in the circulation state of sending out in a boiler again.

  If water supply is continued, the water pressure in the piping 22 will rise (step S102). When the pressure value detected by the pressure detector 23 provided at a predetermined location of the pipe 22 falls within a predetermined range (for example, 23.63 MPa to 24.61 MPa) (YES in step S103), the boiler internal pressure Are in a stable state, the FDF 2 is started, and air is allowed to flow into the boiler 1 (step S104).

  Then, when a predetermined time has elapsed after the activation of the FDF 2 (YES in step S105), purge in the boiler is performed (step S106). The predetermined time here is a time until the inside of the boiler is replaced with fresh air, but the conventional time (execution time of the ventilation process) can be employed as it is (for example, about 5 minutes).

  In the boiler purge, if the fuel residue (unburned material) in the previous plant operation remains in the boiler (furnace), it may lead to an accident such as an explosion in the furnace. This is performed to remove unburned components. Specifically, the wind power is increased by adjusting the power of the FDF 2 or increasing the opening of the damper, and the unburned components are blown away, and discharged outside via a chimney (not shown).

  Subsequently (or in parallel), a fuel leak test is performed (step S107). Specifically, fuel (for example, light oil) is sealed between a predetermined shut-off valve (not shown) and a valve (not shown) closed by the burner 4 for a certain period of time, and the presence or absence of pressure drop is checked to check the fuel. Make sure there are no leaks.

  It should be noted that in general power plants, boiler purge and fuel leak tests are handled as a batch process and are incorporated in the system, and both are generally parallel when executing the boiler purge and fuel leak test process. It is normal to be done.

  If the water supply process is completed after the above process is completed (YES in step S108), the preparation before the ignition of the boiler is completed.

  When the preparation is completed, the steam control valve 21 is closed, fuel such as heavy oil is supplied from the fuel pump 3 from the fuel tank, and burner ignition is performed.

  FIG. 4 is a diagram illustrating an example of the start timing of each process performed by the preparation method before boiler ignition according to the present embodiment. In FIG. 4, the pressure in the boiler becomes stable in 26 minutes after the start of starting the BFP 8, the FDF 2 is started, and after a predetermined time (5 minutes), the boiler purge and fuel leak test process is started. The process is completed after 7 minutes, and at the same time, the water supply process is completed, indicating that the preparations before the ignition of the boiler are completed.

  In addition, the preparation method before the boiler ignition which concerns on this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  For example, in the above embodiment, the pressure of water circulating in the boiler pipe is checked, and the ventilation process is started at a timing when it is considered to be stable. ) Is not limited to this, and any timing may be used even if air is introduced, as long as the required time for the water supply process does not exceed.

It is a figure showing the schematic structure of the power plant concerning one embodiment of the present invention. The expanded side view of the boiler which concerns on the same embodiment is shown. In the same embodiment, it is a flowchart which shows the flow of each preparation before boiler ignition. In the same embodiment, it is a figure which shows an example of the starting timing of each process.

Explanation of symbols

1 Boiler 2 FDF (Indentation Ventilator)
3 Fuel Pump 4 Burner 5 Turbine 6 Generator 7 Condenser 8 BFP (Water Supply Pump)
21 Steam control valve 22 (Inside boiler) piping 23 Pressure detector

Claims (2)

At the time of power plant startup, a water supply process for supplying water into the boiler until a predetermined pressure and a predetermined flow rate, a ventilation process for circulating air until the inside of the boiler is replaced with fresh air, purge and fuel in the boiler A boiler pre-ignition preparation method including a boiler purge for performing a leak check and a fuel leak test process ,
In the water supply process, the water supplied to the boiler ing to the predetermined pressure, even if the water supply process is not finished, to start the ventilation process, after the ventilating process is completed, the boiler A pre-boiler ignition preparation method characterized by starting an internal purge and fuel leak test process . Wherein the predetermined pressure is a method of preparation before boiler ignition according to claim 1, characterized in 23.63MPa~24.61MPa der Rukoto.

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