阅读说明：本技术 一种超临界循环流化床锅炉bt后防止炉膛结焦的运行调控方法 (Operation regulation and control method for preventing hearth from coking after BT (BT) of supercritical circulating fluidized bed boiler ) 是由 郑兴胜 郭强 吴朝刚 李果 李维成 周棋 苏虎 巩李明 薛燕辉 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种超临界循环流化床锅炉BT后防止炉膛结焦的运行调控方法包括：S1锅炉床温高于650℃；S2启动风机；S3加大一次流化风量,使炉膛中/下层床温温升稳定；S4逐渐降低一次流化风量；S5立即启动给煤机进行投煤；S6判断炉膛密相区中/下层床温随煤量和流化风量的变化,以及炉膛差压是否正常,若正常则执行S7,否则执行S10；S7判断锅炉是否超温,若超温则执行S8,否则执行S9；S8开大汽机高、低旁；S9锅炉及机组正常运行；S10停止给煤或减少给煤量,然后进行脉冲式吹扫,若无改善则停炉。本发明能够有效避免超临界CFB锅炉BT后,在重启过程中出现炉内堆积燃料爆燃,床温快速飞升,造成炉膛结焦,造成锅炉重启失败和机组事故停炉的问题。(The invention discloses an operation regulation and control method for preventing a hearth from coking after a supercritical circulating fluidized bed boiler BT (BT) is adopted, which comprises the following steps: the bed temperature of the S1 boiler is higher than 650 ℃; s2, starting the fan; s3, increasing the primary fluidized air quantity to stabilize the temperature rise of the bed at the middle/lower layer of the hearth; s4, gradually reducing the primary fluidization air quantity; s5, immediately starting a coal feeder to feed coal; s6, judging whether the bed temperature of the middle/lower layer in the dense phase region of the hearth changes along with the coal quantity and the fluidization air quantity and whether the differential pressure of the hearth is normal or not, if so, executing S7, otherwise, executing S10; s7, judging whether the boiler is over-temperature, if so, executing S8, otherwise, executing S9; s8, starting the high and low sides of the steam turbine; s9 normal operation of the boiler and the unit; and S10, stopping feeding coal or reducing the feeding coal amount, then performing pulse purging, and stopping the furnace if no improvement exists. The method can effectively avoid the problems of boiler restart failure and unit accident shutdown caused by hearth coking caused by deflagration of accumulated fuel in the boiler and rapid rise of bed temperature in the restart process of the supercritical CFB boiler BT.)

1. An operation regulation and control method for preventing a hearth from coking after a supercritical circulating fluidized bed boiler BT is characterized by comprising the following steps:

s1, when the temperature of the boiler bed is higher than 650 ℃, starting without oil feeding, and executing S2;

s2, starting the fan, and executing S3;

s3, increasing the primary fluidizing air quantity of the left side and the right side of the air chamber to be more than 300KNm³The temperature rise of the bed at the middle/lower layer of the dense-phase zone of the hearth is stable, and S4 is executed;

s4, gradually reducing the primary fluidizing air quantity of the left side and the right side of the air chamber to 200KNm³Step h, executing S5 when the fluidization air volume is stable;

s5, starting the coal feeder immediately to feed coal, and executing S6;

s6, judging whether the bed temperature of the middle/lower layer in the dense phase region of the hearth changes along with the coal quantity and the fluidization air quantity and whether the differential pressure of the hearth is normal or not, if so, executing S7, otherwise, executing S10;

s7, continuing heating and boosting the boiler, judging whether the boiler exceeds the highest temperature of the steam turbine, if so, executing S8, otherwise, executing S9;

s8, opening the high side and the low side of the steam turbine, and opening to exhaust steam to the air;

s9, performing steam turbine conversion and unit grid connection to enable the boiler and the unit to normally operate;

s10, controlling the coal feeder to stop feeding coal or reduce the coal feeding amount, and then adopting the coal feeding amount larger than 350KNm³And pulse purging is carried out on the primary fluidized air volume per hour, whether the bed temperature of the middle/lower layer of the dense-phase region of the hearth changes normally along with the coal volume and the fluidized air volume is observed, and if the bed temperature is not normal, the furnace is shut down.

2. The operation control method for preventing the furnace from coking after the supercritical circulating fluidized bed boiler BT according to claim 1, wherein in step S1, when the temperature of the boiler bed is lower than 650 ℃, oil feeding start is performed, the fan is started and an oil gun under the bed is put into the boiler bed, after the temperature of the boiler bed rises to 650 ℃ and is stable and normal, the oil gun under the bed is stopped, and then S5-S10 are performed.

3. The operation control method for preventing the coking of the hearth after the BT in the supercritical circulating fluidized bed boiler according to claim 1, wherein in the step S3, the stable temperature rise of the hearth middle/lower layer bed means that the temperature rise rate is less than 10 ℃/min.

4. The operation control method for preventing the coking of the furnace after the supercritical circulating fluidized bed boiler BT according to claim 1 or 3, wherein in the step S3, if the bed temperature rise of the middle/lower layer of the furnace is unstable, the primary fluidized air volume is increased again.

5. The operation control method for preventing the coking of the furnace after the BT in the supercritical circulating fluidized bed boiler according to claim 1, wherein in the step S4, the stable air volume to be fluidized means that the displayed value of the bed temperature of the middle/lower layer of the furnace is normal and the deviation is less than 50 ℃, and the differential pressure of the furnace is more than 14 KPa.

6. The operation control method for preventing the furnace from coking after the supercritical circulating fluidized bed boiler BT according to claim 1, wherein in step S9, after the boiler and the unit normally operate, the amount of coal is controlled to increase or decrease < 5t/h, and the load lifting rate is controlled to be < 12 MW/min.

Technical Field

The invention relates to the technical field of circulating fluidized bed boilers, in particular to an operation regulation and control method for preventing a hearth from coking after a supercritical circulating fluidized bed boiler BT.

Background

The main direction of development of Circulating Fluidized Bed (CFB) boilers is large-scale and supercritical (super) critical parameters, CFB boilers with 350MW and 600MW grade supercritical parameters are put into commercial operation at present, and then CFB boilers with larger capacity and super supercritical parameters (660 MW, Wei Hz 660MW, Guizhou) are put into commercial operation.

The 300MW subcritical CFB boiler put into operation at an early stage and the 600MW, 350MW supercritical CFB boiler put into operation at present cause boiler BT (accident shutdown) due to various reasons such as unit equipment, power grid, manual operation and the like. In the process of restarting the boiler BT, coking accidents occur for many times due to operation misoperation and improper treatment measures, so that the operation of the boiler and a unit fails.

A Baima 600MW supercritical CFB boiler is a CBF boiler with the maximum capacity and supercritical parameters for the first operation of the boiler, multiple boiler BT accidents occur at the initial stage of boiler starting and commissioning, and serious coking of a hearth occurs due to improper operation in the subsequent fire-pressing starting process, so that the accidents of damage of an air cap in the boiler and falling off of a water wall castable are caused.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the existing problems, the operation regulation and control method for preventing the hearth from coking after the supercritical circulating fluidized bed boiler BT is provided, and the quick start and the safe and stable operation of the boiler are effectively ensured.

The technical scheme adopted by the invention is as follows:

an operation regulation and control method for preventing a hearth from coking after a supercritical circulating fluidized bed boiler BT, which comprises the following steps:

s1, when the temperature of the boiler bed is higher than 650 ℃, starting without oil feeding, and executing S2;

s2, starting the fan, and executing S3;

s3, increasing the primary fluidizing air quantity of the left side and the right side of the air chamber to be more than 300KNm³The temperature rise of the bed at the middle/lower layer of the dense-phase zone of the hearth is stable, and S4 is executed;

s4, gradually reducing the primary fluidizing air quantity of the left side and the right side of the air chamber to 200KNm³Step h, executing S5 when the fluidization air volume is stable;

s5, starting the coal feeder immediately to feed coal, and executing S6;

s6, judging whether the bed temperature of the middle/lower layer in the dense phase region of the hearth changes along with the coal quantity and the fluidization air quantity and whether the differential pressure of the hearth is normal or not, if so, executing S7, otherwise, executing S10;

s7, continuing heating and boosting the boiler, judging whether the boiler exceeds the highest temperature of the steam turbine, if so, executing S8, otherwise, executing S9;

s8, opening the high side and the low side of the steam turbine, and opening to exhaust steam to the air;

s9, performing steam turbine conversion and unit grid connection to enable the boiler and the unit to normally operate;

s10, controlling the coal feeder to stop feeding coal or reduce the coal feeding amount, and then adopting the coal feeding amount larger than 350KNm³And pulse purging is carried out on the primary fluidized air volume per hour, whether the bed temperature of the middle/lower layer of the dense-phase region of the hearth changes normally along with the coal volume and the fluidized air volume is observed, and if the bed temperature is not normal, the furnace is shut down.

Further, in step S1, when the temperature of the boiler bed is lower than 650 ℃, oil feeding is started, the blower is started and the oil gun under the bed is fed, after the temperature of the boiler bed rises to 650 ℃ and is stable and normal, the oil gun under the bed is stopped, and then S5 to S10 are executed.

Further, in step S3, the stable temperature rise of the middle/lower bed layer in the dense-phase zone of the furnace chamber means that the temperature rise rate is less than 10 ℃/min.

Further, in step S3, if the bed temperature rise in the middle/lower layer of the dense-phase zone of the furnace is not stable, the primary fluidized air volume is increased again.

Further, in step S4, the stable air flow to be fluidized means that the bed temperature in the middle/lower layer of the dense-phase zone of the furnace is normal and the deviation is less than 50 ℃, and the differential pressure of the furnace is more than 14 KPa.

Further, in step S9, after the boiler and the unit normally operate, the coal amount is controlled to be increased or decreased to be less than 5t/h, and the load lifting rate is controlled to be less than 12 MW/min.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the method can effectively avoid the problems of boiler restart failure and unit accident shutdown caused by hearth coking caused by deflagration of accumulated fuel in the boiler and rapid rise of bed temperature in the restart process of the supercritical CFB boiler BT.

2. The invention can effectively prevent and quickly process the boiler BT accident, and then cause the restart shutdown accident again, thereby ensuring the safe operation and normal production of the power plant equipment and avoiding causing huge economic loss to the power plant (the boiler needs to be restarted once at least and costs more than million yuan).

3. At present, the number of supercritical CFB boiler units is large, the supercritical CFB boiler is put into operation at present, and in the whole starting process and the initial trial run stage, due to improper operation and debugging methods and insufficient debugging experience, the restarting and coking accidents after the boiler BT accidents easily occur, so that secondary shutdown is caused, and therefore the technical scheme of the invention has good guiding effect and practical value.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a flow chart of the operation regulation and control method for preventing the hearth from coking after the supercritical circulating fluidized bed boiler BT is adopted.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, an operation regulation and control method for preventing a hearth from coking after a supercritical circulating fluidized bed boiler BT comprises the following steps:

s1, when the temperature of the boiler bed is higher than 650 ℃, starting without oil feeding, and executing S2;

in some embodiments, when the temperature of the boiler bed is lower than 650 ℃, oil feeding starting is carried out, a fan is started and an oil gun under the bed is put in, after the temperature of the boiler bed is raised to 650 ℃ and is stable and normal, the oil gun under the bed is stopped, and then S5-S10 are carried out;

s2, starting the fan, and executing S3;

s3, increasing the primary fluidizing air quantity of the left side and the right side of the air chamber to be more than 300KNm³The temperature rise of the bed at the middle/lower layer of the dense-phase zone of the hearth is stable, and S4 is executed; the stable bed temperature rise of the middle/lower layer in the dense-phase zone of the hearth refers to that: the temperature rise rate is less than 10 ℃/min, and the stable temperature rise is the bed temperature and the stable combustion; in addition, if the temperature rise of the bed temperature of the middle layer or the lower layer in the dense-phase region of the hearth is unstable, the primary fluidized air quantity is increased again until the temperature of the bed temperature of the middle layer or the lower layer in the dense-phase region of the hearth does not rapidly rise any more (namely the temperature rise rate)＜10℃/min)；

S4, gradually reducing the primary fluidizing air quantity of the left side and the right side of the air chamber to 200KNm³Step h, executing S5 when the fluidization air volume is stable; the stable air quantity to be fluidized means that the displayed value of the bed temperature of the middle/lower layer in the dense-phase region of the furnace hearth is normal and the deviation is less than 50 ℃, and the differential pressure of the furnace hearth is more than 14 KPa;

s5, starting the coal feeder immediately to feed coal, and executing S6; namely, the coal feeder should be started immediately after the fluidized air volume is stable to prevent the bed temperature from dropping rapidly;

s6, judging whether the bed temperature of the middle/lower layer in the dense phase region of the hearth changes along with the coal quantity and the fluidization air quantity and whether the differential pressure of the hearth is normal or not, if so, executing S7, otherwise, executing S10; the abnormal change of the bed temperature of the middle/lower layer in the dense-phase zone of the hearth along with the coal quantity and the fluidization air quantity refers to that: the bed temperature of the middle/lower layer of the dense-phase region of the hearth cannot change along with the coal quantity and the fluidized air quantity or change abnormally; when the bed temperature changes and the hearth differential pressure abnormally fluctuates, if the coking phenomenon is considered to occur, S10 is executed;

s7, continuing to heat and boost the boiler, and judging whether the boiler exceeds the highest temperature of the steam turbine to make a transition (generally 500 ℃), if so, executing S8, otherwise, executing S9;

s8, opening the high side and the low side of the steam turbine (the original opening degree of the high side and the low side of the steam turbine is lower than 10%, and the opening is required to be larger than 10%), and opening to exhaust steam to the air to avoid the overtemperature of the heated surface wall of the boiler and the steam temperature for a long time (not allowed to be larger than 2 hours);

s9, performing steam turbine conversion and unit grid connection to enable the boiler and the unit to normally operate; after the boiler and the unit normally operate, controlling the coal quantity to be increased and decreased to be less than 5t/h and the load lifting rate to be less than 12 MW/min;

s10, controlling the coal feeder to stop feeding coal or reduce the coal feeding amount (generally reducing by 5-10t/h each time), and then adopting more than 350KNm³And pulse purging is carried out on the primary fluidized air volume per hour, whether the bed temperature of the middle/lower layer of the dense-phase region of the hearth changes normally along with the coal volume and the fluidized air volume is observed, and if the bed temperature is not normal, the furnace is shut down.