CN-121977195-A - Boiler instantaneous energy precise regulation and control rapid load change system and control method

CN121977195ACN 121977195 ACN121977195 ACN 121977195ACN-121977195-A

Abstract

The invention relates to the technical field of coal-fired power plant boilers and provides a boiler instantaneous energy precise regulation and control rapid load-changing system and a control method, wherein the system comprises a main steam system, a reheat steam system, a first bypass steam system, a second bypass steam system and a control unit, wherein an inlet of the first bypass steam system is connected to a water-cooled wall outlet of the main steam system, and an outlet of the first bypass steam system is connected to a screen-type superheater inlet of the main steam system; the control unit is configured to adjust the steam working medium flow rates of the first bypass steam system and the second bypass steam system according to a load instruction during the load rising period of the unit. The scheme has low reconstruction cost and small implementation difficulty, and provides a feasible technical path for realizing rapid load change and accurate energy quality regulation and control standard reaching of the active machine set.

Inventors

FAN QINGWEI
ZHANG FENG
SHI YONGQIANG
LIU YANG
Lei Lifu
HUANG YUPING

Assignees

西安热工研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260205

Claims (10)

1. The boiler instantaneous energy precise regulation and control rapid load change system is characterized by further comprising a first bypass steam system (11), a second bypass steam system (12) and a control unit respectively connected with the first bypass steam system (11) and the second bypass steam system (12), wherein an inlet of the first bypass steam system (11) is connected to an outlet of a water cooling wall (2) of the main steam system, an outlet of the first bypass steam system is connected to an inlet of a screen-type superheater (5) of the main steam system, an inlet of the second bypass steam system (12) is connected to an outlet of a low-temperature reheater (7) of the reheat steam system, an outlet of the second bypass steam system is connected to an inlet of a high-temperature reheater (8) of the reheat steam system, and the control unit is configured to regulate steam working medium flow rates of the first bypass steam system (11) and the second bypass steam system (12) in real time according to load instructions during unit load increase and is used for precisely matching total heat energy input into a boiler.
2. The boiler instantaneous energy precise regulation and control rapid load change system according to claim 1 is characterized in that the main steam system sequentially comprises an economizer (11), a water cooling wall (2), a wall-covering superheater (3), a low-temperature superheater (4), a screen superheater (5) and a high-temperature superheater (6) according to the steam flow direction, the high-temperature superheater (6) is communicated with a turbine high-pressure cylinder (9), the reheat steam system sequentially comprises a low-temperature reheater (7) and a high-temperature reheater (8) according to the steam flow direction, and the high-temperature reheater (8) is communicated with a turbine intermediate-pressure cylinder (10).
3. The boiler instantaneous energy precise regulation and control rapid load change system according to claim 1, wherein the pipelines of the first bypass steam system (11) and the second bypass steam system (12) are respectively provided with a regulating valve group capable of realizing real-time independent flow regulation.
4. The boiler instantaneous energy precise regulation and control rapid load change system according to claim 1, wherein the control unit is further configured to control the first bypass steam system (11) and the second bypass steam system (12) to operate in a higher flow state for matching the boiler instantaneous greatly increased fuel heat energy at the initial stage of load increase, to control the flow rate of the first bypass steam system (11) and the second bypass steam system (12) to gradually decrease for matching the reduction of the boiler fuel overshoot at the middle stage of load increase, and to control the flow rate of the first bypass steam system (11) and the second bypass steam system (12) to gradually close to zero for matching the reverse overshoot of the boiler fuel deficiency at the later stage of load increase.
5. The method for controlling the instantaneous energy quality accurate regulation and rapid load change of the boiler by the system according to any one of claims 1to 4 is characterized by comprising the following steps: Receiving an automatic power generation control load increasing instruction, wherein the instruction comprises a target load increment delta P and an initial load P 0 ; According to the instruction, on the basis of the overshoot factor A set by the original fuel control instruction, an additional overshoot factor B is further added, so that the total fuel increment delta B 2 is satisfied with delta B 2 =B×A×(ΔP/P 0 )×b 0 , wherein B 0 is an initial fuel instruction, and B >1; synchronously increasing the boiler water supply flow for matching the instantaneous heat energy overshoot of the boiler; the first bypass steam system (11) is started, the steam flow of the first bypass steam system is regulated and controlled to be the water supply flow which is set to be 0.9 multiplied by (B-1), the second bypass steam system (12) is started, and the reheat steam flow of the second bypass steam system is regulated and controlled to be the steam flow which is set to be 0.9 multiplied by (B-1).
6. The method for controlling the instantaneous energy precise regulation and control rapid load change of the boiler according to claim 5, wherein the additional overshoot factor B is determined according to the target load rise time Deltat 1 and the actual required load rise time Deltat 2 of the unit, and B=1+ (t 2 - t 1 ) / t 1 , wherein t 1 is a theoretical target moment, and t 2 is a moment when the target load is actually reached when the unit is not modified.
7. The method for controlling the instantaneous energy precise regulation and control rapid load change of the boiler according to claim 6, wherein the additional overshoot factor B is dynamically changed in the load increasing process, and is rapidly increased from 1 to 1+ (t 2 - t 1 ) / t 1 ) in a period from t 0 to t 1 , and is rapidly decreased from 1+ (t 2 - t 1 ) / t 1 to 1) in a period from t 1 to t 2 .
8. The method for controlling the instantaneous energy quality accurate regulation and control rapid load change of the boiler according to claim 5, wherein the flow rate of the first bypass steam system (11) is a real-time regulation variable, and the method is characterized in that the flow rate of the first bypass steam system (11) is increased if the screen type superheater is overtemperature, and the flow rate of the first bypass steam system (11) is reduced on the premise of ensuring that the screen type superheater is not overtemperature if the main steam temperature is greatly reduced.
9. The method for controlling the instantaneous energy quality accurate regulation and control rapid load change of the boiler according to claim 5, wherein the flow rate of the second bypass steam system (12) is a real-time regulation variable, and the method is modified by increasing the flow rate of the second bypass steam system (12) if the high-temperature reheater is over-temperature and decreasing the flow rate of the second bypass steam system (12) if the high-temperature reheater steam temperature is greatly reduced.
10. The method for controlling the instantaneous energy quality accurate regulation and control of the rapid variable load of the boiler according to claim 5, wherein the value of A is 1.2-2.0.

Description

Boiler instantaneous energy precise regulation and control rapid load change system and control method Technical Field The invention relates to the technical field of coal-fired power station boilers, in particular to a boiler instantaneous energy precise regulation and control rapid load change system and a control method. Background The energy structure in China has the remarkable characteristics of more coal, less oil and less gas, which determines the long-term dominant position of the coal-fired thermal power in the installed capacity and the generated energy. However, with the rapid increase of the ratio of new energy installation to power generation, the role of coal-fired thermal power units is gradually changed from dominant power to guaranteed power. In order to meet the requirement of a novel power system on flexible regulation capability, in the action implementation scheme (2025-2027 years) special for upgrading new generation coal and electricity (originating and modifying energy source [ 2025 ] 363), a higher standard is provided for the load response rate of a coal-fired thermal power unit. The existing coal-fired unit is difficult to meet the performance index set by the document without key technical transformation, and especially cannot realize the requirements of accurate regulation and control of instantaneous energy and rapid load change of the boiler. A central factor limiting the load response capability of coal-fired units is the thermal inertia of the boiler system. After receiving the load increasing instruction, the boiler can convert the chemical energy of the fuel into the heat energy of the steam through a series of complex processes such as fuel regulation, fuel preparation, combustion heat release, gradual heat absorption of a heating surface and the like. In contrast, the conversion process of steam heat energy into electric energy is quick in response and less restricted. Therefore, the method and the device improve the internal energy conversion speed of the boiler and enhance the steam output efficiency, and become the key for breaking through the thermal inertia bottleneck of the boiler. The heat absorption process in the boiler is extremely complicated, namely, the water supply firstly absorbs radiant heat in the water-cooled wall of the hearth to generate superheated steam, the heat transfer rate is higher at the stage, then, the steam flows through the wall-wrapped superheater and the low-temperature superheater to form primary superheated steam through convection heat exchange, the stage is limited by the heat transfer coefficient of the flue gas side and the flue gas temperature, the heat transfer rate is obviously slowed down, the primary superheated steam returns to the upper part of the hearth, the radiant heat is absorbed again in the screen-type superheater, the heat transfer rate is higher, and finally, the final heating is finished in the high-temperature superheater, and the stage has the characteristics of radiation and convection heat exchange and the heat transfer rate is centered. Therefore, in the whole steam generation flow, the link with the slowest heat transfer rate is concentrated on the wall-wrapped superheater and the low-temperature superheater which are positioned at the front section, so that the overall variable load response performance is impaired, and the core bottleneck which restricts the accurate regulation and control of the instantaneous energy quality is formed. In the aspect of flue gas flow, the fuel combustion reaction is rapid, the released heat is rapidly transferred to the water-cooled wall and the screen-type superheater in a radiation mode, and after the flue gas enters the high-temperature superheater and the tail heating surface, the temperature is reduced, the convection heat transfer coefficient is reduced, and a heat transfer hysteresis zone is formed. The heat transfer characteristics of the two sides of the steam and the flue gas are combined, and the main source of the thermal inertia of the boiler is not a radiation heat absorption area in the hearth, but a medium-low temperature convection heat absorption stage after the hearth outlet. In summary, in the process of lifting load of the boiler, the total input heat of the instantaneous boiler is concentrated in the furnace area of the boiler, and at this time, the water supply flow of the boiler cannot be completely matched with the total input energy, otherwise, the problem of reduced steam parameters caused by insufficient heat absorption capacity of the heating surface at the tail of the boiler is expressed as mismatching between the total input heat of the boiler and the flow of working medium. If the total fuel input amount of the boiler is forcibly increased, the high-temperature heating surfaces such as the water-cooled wall, the screen type superheater and the like can be possibly overheated due to relatively small flow of working medium. Therefore, in the pr