Implementation method of single auxiliary machine steam pump RB of circulating fluidized bed unit

Abstract

The invention discloses an implementation method of a single auxiliary machine steam pump RB of a circulating fluidized bed unit, which comprises the following steps: after the steam pump trips, the action condition of the steam pump RB: opening a front electric door and a rear electric door of a boiler water supply bypass adjusting door when the RB acts; when the RB acts, the current of the electric pump is 200A and the outlet pressure of the electric pump is more than 20MPa, an outlet regulating valve of the electric pump is opened to 35%; coordinating to a turbine following TF mode, and forcibly switching a unit operation mode to a sliding pressure mode; after RB occurs, AGC is automatically cut off, meanwhile, an instruction is sent to a DEH system, and a sequence valve is cut into a single valve; and when the load of the unit is reduced to the target load for 3 seconds or the operator presses down a steam pump RB ending button, the RB process is ended. The system has the advantages that after the single steam pump trips, the unit load is changed to the target load without manual intervention of an operator, so that the operation intensity of the operator in an accident state is greatly reduced, and the probability of misoperation of the operator is reduced; the load range of a boiler BT is increased from 80MW to 160MW when a steam pump trips out, so that a larger safe and stable operation space is provided for a unit; bT accidents are avoided, and the purpose of saving coal consumption is achieved.

Description

Technical Field

[0001] The invention relates to a steam pump operation method, in particular to a method for realizing a single auxiliary steam pump RB of a circulating fluidized bed unit. Background Art

[0002] In the 300MW circulating fluidized bed unit, the steam pump is a single auxiliary machine configuration, equipped with a 100% load steam pump and a 30% load electric pump. During the normal operation of the unit, BT tripping occurs, and the unit's load capacity decreases. The operating personnel need to quickly complete the unit's load reduction, switch the feedwater bypass, and adjust the electric pump outlet valve to maintain the main steam pressure and load steadily reduced, as well as the stability of the drum water level. The operation is difficult, requires high psychological quality of the on-duty personnel, and is prone to accidents. The control method of the steam pump trip RB is faster and more accurate than manual operation, so that the steam pump trip does not trigger the increase in the load range of the boiler BT, which can give the unit a larger safe and stable operation space. The goal of "steam pump tripping triggers steam-driven feedwater pump RB, the unit automatically and quickly sheds load to 100MW, the coal feeder and primary and secondary fans are automatically controlled, the feedwater is switched from the steam pump to the electric pump, the electric pump outlet valve is automatically adjusted, the feedwater is automatically switched from the main line to the bypass, the main steam pressure and load are maintained to decrease steadily, and the drum water level is kept stable until the steam-driven feedwater pump RB ends" has been achieved. It has been demonstrated that when the load is less than 160MW, the steam pump tripping triggers the steam-driven feedwater pump RB, and the unit automatically and quickly sheds load to 100MW, so that the steam pump tripping can ensure that the boiler BT is not triggered, and the load range in which the steam pump tripping does not trigger the boiler BT is increased from 80MW to 160MW. The steam pump tripping and high bed temperature have been modified to when the load is less than 160MW, the steam pump tripping will not trigger the boiler BT. This requires that after the steam pump tripping, the operating personnel must quickly complete the unit load reduction, switch the feed water bypass and adjust the electric pump outlet valve to maintain a steady reduction in main steam pressure and load, as well as stability of the boiler drum water level. The operation is difficult, has high psychological requirements for the on-duty personnel, and is prone to accidents. Summary of the invention

[0003] The object of the present invention is to provide a method for realizing a single auxiliary steam pump RB of a circulating fluidized bed unit to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for realizing a single auxiliary steam pump RB of a circulating fluidized bed unit comprises the following steps: after the steam pump trips, the steam pump RB operates:

[0006] 1.1. When RB is in action, open the front and rear electric doors of the boiler feed water bypass adjustment door. After the front and rear electric doors are fully opened, open the bypass adjustment door to 100%. When the bypass adjustment door is opened to 30%, close the main feed water electric door;

[0007] 1.2. When RB is in action, when the electric pump current is 200A and the electric pump outlet pressure is above 20MPa, open the electric pump outlet regulating valve to 35%, that is, give the valve adjustment command to 35%, open the electric pump middle tap electric door in parallel, and after the electric pump outlet regulating valve is greater than 30%, close the electric pump and recirculate to 30%;

[0008] 1.3. Coordinate and switch to the turbine following TF mode, the unit operation mode is forcibly switched to the sliding pressure mode, the RB sliding pressure rate is 0.5MPa / min, and when the main steam pressure is greater than 16.2MPa, the turbine control door is closed and the boiler main control is switched to manual;

[0009] Sliding pressure curve:

[0010]

[0011] 1.4. After RB occurs, AGC is automatically cut off and a command is sent to the DEH system at the same time, and the sequence valve is cut into a single valve;

[0012] 1.5. When No. 2 and No. 7 coal feeders are running after RB occurs, No. 1 and No. 8 coal feeders are shut down, and the coal flow of No. 2 and No. 7 coal feeders is automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5, and No. 6 coal feeders is automatically adjusted to 10t / h;

[0013] 1.6. When No. 2 coal feeder stops operating after RB occurs, only No. 8 coal feeder will be switched off, and the coal flow of No. 1 and No. 7 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h;

[0014] 1.7. When No. 7 coal feeder stops operating after RB occurs, only No. 1 coal feeder will be tripped, and the coal flow of No. 2 and No. 8 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h;

[0015] 1.8. After RB occurs, all dampers of the secondary air are automatically closed to 10%, and the secondary fan rotor blades are automatically closed to 10%. After the rotor blades are in place, the secondary fan is automatically opened for recirculation to 100%, and the recirculation rate is not more than 1% / second;

[0016] 1.9. After RB occurs, the primary wind turbine blades automatically close to 50% at a rate no greater than 1% / second;

[0017] 1.10. After RB occurs, the opening of all superheater and reheater cooling water adjustment doors will automatically reduce by 50% of the current opening (5-second pulse), and ensure that the cooling water will not automatically exit due to large deviations;

[0018] 1.11. Steam pump RB ends: When the unit load drops to the target load for 3 seconds or the operator presses the steam pump RB end button, the RB process ends.

[0019] Furthermore, the operating conditions of this patent are as follows:

[0020] 1. The steam pump RB function is automatically put into operation: the steam pump is running, the electric pump is stopped, the unit coordinated control mode is put into operation, and the unit active power is greater than 110MW. If all four conditions are met, the RB function is automatically put into operation;

[0021] 2. Automatic cut-off of steam pump RB function:

[0022] (1) The unit steam turbine master control is not automatically put into operation, and the RB function is automatically cut off;

[0023] (2) When the active power of the unit is less than 100MW, the RB function will be automatically cut off;

[0024] (3) When the electric pump is running, the RB function is automatically cut off;

[0025] 3. Steam pump RB action conditions:

[0026] When the RB function is in operation, the steam pump trips and the boiler BT signal is not sent, triggering the steam pump RB action.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The tripping of a single steam pump triggers the steam-driven feedwater pump RB, and the unit automatically dumps the load to 100MW. The coal feeder and primary and secondary fans are automatically controlled, and the feedwater is switched from the steam pump to the electric pump, realizing automatic adjustment of the electric pump outlet valve. The feedwater is automatically switched from the main line to the bypass, maintaining a steady decrease in the main steam pressure and load, and keeping the drum water level stable until the steam-driven feedwater pump RB stops;

[0029] (2) After a single steam pump trips, the unit load is reduced to the target load without manual intervention by the operator, which greatly reduces the operating intensity of the operator in an accident state and reduces the probability of operator error;

[0030] (3) The load range in which the steam pump tripping does not trigger the boiler BT is increased from 80MW to 160MW, giving the unit more room for safe and stable operation;

[0031] (4) Avoid BT accidents and save coal consumption. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In an embodiment of the present invention, a method for realizing a single auxiliary steam pump RB of a circulating fluidized bed unit includes the following steps: after the steam pump trips, the action of the steam pump RB is:

[0034] 1.1. When RB is in action, open the front and rear electric doors of the boiler feed water bypass adjustment door. After the front and rear electric doors are fully opened, open the bypass adjustment door to 100%. When the bypass adjustment door is opened to 30%, close the main feed water electric door;

[0035] 1.2. When RB is in action, when the electric pump current is 200A and the electric pump outlet pressure is above 20MPa, open the electric pump outlet regulating valve to 35%, that is, give the valve adjustment command to 35%, open the electric pump middle tap electric door in parallel, and after the electric pump outlet regulating valve is greater than 30%, close the electric pump and recirculate to 30%;

[0036] 1.3. Coordinate and switch to the turbine following TF mode, the unit operation mode is forcibly switched to the sliding pressure mode, the RB sliding pressure rate is 0.5MPa / min, and when the main steam pressure is greater than 16.2MPa, the turbine control door is closed and the boiler main control is switched to manual;

[0037] Sliding pressure curve:

[0038]

[0039] 1.4. After RB occurs, AGC is automatically cut off and a command is sent to the DEH system at the same time, and the sequence valve is cut into a single valve;

[0040] 1.5. When No. 2 and No. 7 coal feeders are running after RB occurs, No. 1 and No. 8 coal feeders are shut down, and the coal flow of No. 2 and No. 7 coal feeders is automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5, and No. 6 coal feeders is automatically adjusted to 10t / h;

[0041] 1.6. When No. 2 coal feeder stops operating after RB occurs, only No. 8 coal feeder will be switched off, and the coal flow of No. 1 and No. 7 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h;

[0042] 1.7. When No. 7 coal feeder stops operating after RB occurs, only No. 1 coal feeder will be tripped, and the coal flow of No. 2 and No. 8 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h;

[0043] 1.8. After RB occurs, all dampers of the secondary air are automatically closed to 10%, and the secondary fan rotor blades are automatically closed to 10%. After the rotor blades are in place, the secondary fan is automatically opened for recirculation to 100%, and the recirculation rate is not more than 1% / second;

[0044] 1.9. After RB occurs, the primary wind turbine blades automatically close to 50% at a rate no greater than 1% / second;

[0045] 1.10. After RB occurs, the opening of all superheater and reheater cooling water adjustment doors will automatically reduce by 50% of the current opening (5-second pulse), and ensure that the cooling water will not automatically exit due to large deviations;

[0046] 1.11. Steam pump RB ends: When the unit load drops to the target load for 3 seconds or the operator presses the steam pump RB end button, the RB process ends.

[0047] Furthermore, the operating conditions of this patent are as follows:

[0048] 1. The steam pump RB function is automatically put into operation: the steam pump is running, the electric pump is stopped, the unit coordinated control mode is put into operation, and the unit active power is greater than 110MW. If all four conditions are met, the RB function is automatically put into operation;

[0049] 2. Automatic cut-off of steam pump RB function:

[0050] (1) The unit steam turbine master control is not automatically put into operation, and the RB function is automatically cut off;

[0051] (2) When the active power of the unit is less than 100MW, the RB function will be automatically cut off;

[0052] (3) When the electric pump is running, the RB function is automatically cut off;

[0053] 3. Steam pump RB action conditions:

[0054] When the RB function is in operation, the steam pump trips and the boiler BT signal is not sent, triggering the steam pump RB action.

[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for realizing a single auxiliary steam pump RB of a circulating fluidized bed unit, characterized in that it comprises the following steps: after the steam pump trips, the action of the steam pump RB: 1.

1. When RB is in action, open the front and rear electric doors of the boiler feed water bypass adjustment door. After the front and rear electric doors are fully opened, open the bypass adjustment door to 100%. When the bypass adjustment door is opened to 30%, close the main feed water electric door; 1.

2. When RB is in action, when the electric pump current is 200A and the electric pump outlet pressure is above 20MPa, open the electric pump outlet regulating valve to 35%, that is, give the valve adjustment command to 35%, open the electric pump middle tap electric door in parallel, and after the electric pump outlet regulating valve is greater than 30%, close the electric pump and recirculate to 30%; 1.

3. Coordinate and switch to the turbine following TF mode, the unit operation mode is forcibly switched to the sliding pressure mode, the RB sliding pressure rate is 0.5MPa / min, and when the main steam pressure is greater than 16.2MPa, the turbine control door is closed and the boiler main control is switched to manual; 1.

4. After RB occurs, AGC is automatically cut off and a command is sent to the DEH system at the same time, and the sequence valve is cut into a single valve; 1.

5. When No. 2 and No. 7 coal feeders are running after RB occurs, No. 1 and No. 8 coal feeders are shut down, and the coal flow of No. 2 and No. 7 coal feeders is automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5, and No. 6 coal feeders is automatically adjusted to 10t / h; 1.

6. When No. 2 coal feeder stops operating after RB occurs, only No. 8 coal feeder will be switched off, and the coal flow of No. 1 and No. 7 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h; 1.

7. When No. 7 coal feeder stops operating after RB occurs, only No. 1 coal feeder will be tripped, and the coal flow of No. 2 and No. 8 coal feeders will be automatically adjusted to 17t / h, and the coal flow of No. 3, No. 4, No. 5 and No. 6 coal feeders will be automatically adjusted to 10t / h; 1.

8. After RB occurs, all dampers of the secondary air are automatically closed to 10%, and the secondary fan rotor blades are automatically closed to 10%. After the rotor blades are in place, the secondary fan is automatically opened for recirculation to 100%, and the recirculation rate is not more than 1% / second; 1.

9. After RB occurs, the primary wind turbine blades automatically close to 50% at a rate no greater than 1% / second; 1.

10. After RB occurs, the opening of all superheater and reheater cooling water adjustment doors will automatically reduce by 50% of the current opening, i.e. 5-second pulse, and ensure that the cooling water will not automatically exit due to large deviation; 1.

11. Steam pump RB ends: When the unit load drops to the target load for 3 seconds or the operator presses the steam pump RB end button, the RB process ends.

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