CN-121976884-A - Method for starting indirect combustion type biomass gas turbine

CN121976884ACN 121976884 ACN121976884 ACN 121976884ACN-121976884-A

Abstract

The invention belongs to the technical field of gas turbine control and thermal management, and relates to a method for starting an indirect combustion type biomass gas turbine. The invention judges the flow field establishment by taking the key gas quantity and the shafting rotating speed as criteria, and gives consideration to the rapidity and the operation safety margin of starting regulation, meanwhile, judges the wall temperature to be stable by taking the wall temperature of the high-temperature heat exchanger as criteria, relieves the problem of transient temperature difference surge of the pipe wall caused by abrupt change of heat exchange coefficient in the flow establishment process, and in addition, realizes the starting and stopping of dynamic freezing control and the limited climbing of fuel instructions by comparing the multidimensional constraint quantity of the wall temperature with the corresponding threshold value, adapts to the unsteady characteristic of biomass fuel combustion, timely inhibits the generation of transient thermal stress and local hot spot, and realizes the ordered regulation of the starting process and the thermal safety protection of the high-temperature heat exchanger in the whole process.

Inventors

XIE YONGHUI
Wang Chenyin
ZHANG DI
LIU XIJIE

Assignees

西安交通大学

Dates

Publication Date: 20260505
Application Date: 20260401

Claims (9)

1. The method for starting the indirect combustion type biomass gas turbine is characterized by being applied to an indirect combustion type biomass gas turbine system comprising a gas compressor, a turbine, a biomass boiler and a high-temperature heat exchanger, and comprises the following steps of: collecting the outlet pressure of the air compressor, the loop flow of the air compressor, the pressure ratio of the air compressor and the hot end temperature and cold end temperature of the high-temperature heat exchanger in real time; Applying traction torque to a connecting shaft system of the gas compressor and the turbine, accelerating the gas compressor along with the shaft system, and keeping a fuel instruction of the biomass boiler to be zero; Taking the collected outlet pressure of the air compressor, the loop flow of the air compressor and the pressure ratio of the air compressor as key air quantity to form a stability criterion for establishing a flow field, taking the shafting rotating speed as a rotating speed criterion for establishing the flow field, and judging that the flow field is established when the two are satisfied; On the premise of maintaining the establishment of a flow field, hot dipping and temperature equalization are carried out by adopting a low heat input mode in a non-ignition state or without causing sudden rise of the hot end of the high-temperature heat exchanger, the hot end temperature and the cold end temperature of the high-temperature heat exchanger are used as wall temperature criteria, and if the wall temperature criteria are met, the wall temperature is judged to be stable; Under the premise of meeting the establishment of a flow field and the stabilization of wall temperature, ignition control is carried out, so that the biomass boiler enters a combustion state and gradually increases a fuel instruction according to a limited slope strategy, meanwhile, the hot end temperature and the cold end temperature of the high-temperature heat exchanger are continuously collected in a preset control period, the wall temperature multi-dimensional constraint quantity set is determined by utilizing the hot end temperature and the cold end temperature of the high-temperature heat exchanger, any wall temperature multi-dimensional constraint quantity is compared with an entry threshold and an exit threshold, if the wall temperature multi-dimensional constraint quantity is larger than the entry threshold, dynamic freezing control is carried out, the fuel instruction is restrained from increasing, if all the wall temperature multi-dimensional constraint quantities are smaller than the exit threshold, the dynamic freezing control is carried out, the fuel instruction is continuously increased, limited climbing is carried out, and grid-connected operation is carried out when grid-connected conditions are met.
2. The method for starting the indirect combustion type biomass gas turbine according to claim 1, wherein when the hot end temperature and the cold end temperature of the high-temperature heat exchanger are collected, a plurality of axial stations are symmetrically arranged at the hot end and the cold end respectively along the flow direction of the high-temperature heat exchanger, a plurality of circumferential measuring points are symmetrically arranged at each axial station, and the temperatures of each axial station and each circumferential measuring point are collected respectively.
3. The method for starting an indirect combustion type biomass gas turbine according to claim 1, wherein the condition for establishing the rotation speed criterion is that the shafting rotation speed is greater than or equal to a rotation speed minimum threshold value and the state continues for a preset flow field establishment period, and the condition for establishing the stability criterion is that the relative fluctuation amplitude of the key gas momentum is less than or equal to a preset stability tolerance and the state continues for the preset flow field establishment period.
4. The method for starting the indirect combustion type biomass gas turbine according to claim 1, wherein the conditions for establishing the wall temperature criterion are any one or a combination of a first mode that the absolute value of the wall temperature change rate of the hot end and the cold end of the high-temperature heat exchanger is smaller than or equal to a preset wall temperature change rate threshold value in a continuous preset wall temperature stabilizing period, and a second mode that the difference value of the wall temperatures of the hot end and the cold end of the high-temperature heat exchanger in the axial direction or the circumferential direction is smaller than or equal to a preset wall temperature space non-uniformity threshold value in the continuous preset wall temperature stabilizing period.
5. The method of claim 1, wherein the set of wall temperature multidimensional constraints includes at least a maximum wall temperature rate of change constraint, a maximum wall penetration gradient constraint, a maximum axial gradient constraint, and a maximum circumferential gradient constraint.
6. The method for starting an indirect combustion type biomass gas turbine according to claim 1, wherein if the wall temperature multi-dimensional constraint quantity is greater than the entry threshold value, the preset overrun judgment period is required to be continued, and if the wall temperature multi-dimensional constraint quantity is smaller than the exit threshold value, the preset release judgment period is required to be continued.
7. The method for starting an indirect-combustion biomass gas turbine according to claim 1, wherein the preset cancellation determination period is equal to or greater than a preset overrun determination period.
8. The method for starting an indirect combustion type biomass gas turbine according to claim 1, wherein the dynamic freezing control is performed by using any one or a combination of a first method of forcing the fuel command change rate to be zero and keeping the fuel command unchanged and a second method of forcing the fuel command change rate to be less than zero and slowly decreasing the fuel command.
9. The method for starting an indirect combustion type biomass gas turbine according to claim 1, wherein the grid-connected condition at least comprises a state in which the relative fluctuation amplitude of the key gas momentum is smaller than or equal to a preset stability tolerance and the state continues for a preset flow field establishment period, the shafting rotating speed is larger than or equal to a rotating speed minimum threshold and continues for a preset flow field establishment period, and all wall temperature multidimensional constraint quantities are smaller than an exit threshold and continue for a preset release judgment period.

Description

Method for starting indirect combustion type biomass gas turbine Technical Field The invention belongs to the technical field of gas turbine control and thermal management, and relates to a method for starting an indirect combustion type biomass gas turbine. Background The EFGT, i.e. the indirect combustion type gas turbine, is used as an important technical path for connecting solid fuels such as biomass, waste and the like with clean power generation, and has the core advantages that the physical isolation between a combustion side and a working medium side is realized through a high-temperature heat exchanger, dust-containing and corrosive flue gas generated by combustion only flows through an external heat exchanger, and clean compressed air is independently circulated as a turbine working medium, so that the risk of damage to a compressor and turbine blades caused by ash deposition, high-temperature corrosion and particle erosion is remarkably reduced. The technology has been developed in engineering demonstration in small distributed energy stations, micro-grids in remote areas and industrial waste heat coupling power generation systems, and typical systems comprise boilers, high-temperature heat exchangers made of high-temperature resistant metal materials, compressors and turbine sets. At present, in the practical application of the EFGT, the starting stage is a key link of the operation reliability of the EFGT, because the EFGT has the special properties of a multi-loop heat transfer link and a high heat capacity heat exchange structure, the starting process is extremely easy to cause a remarkable heat-mechanical coupling problem, and if the problem cannot be effectively controlled, the service life and the operation safety of equipment can be directly influenced. Aiming at the core problems of the starting stage, a corresponding starting control strategy is formed in the prior art, and the method mainly comprises the following three points of realizing basic regulation and control of fuel supply by adopting a closed-loop fuel regulation mode taking the rotating speed, the turbine exhaust temperature or the turbine inlet side working medium temperature and the like as feedback quantities, adopting a mode of preheating first and then increasing the speed for reducing the unstable operation factors caused by low cold ignition or low-temperature heat exchange efficiency, namely, carrying out ignition preheating to a certain degree on a heat exchanger, and then increasing the turbine rotating speed to establish stable compressor flow after the heat exchanger reaches the proper temperature, and the third step of taking the upper limit of the working medium temperature such as the limiting turbine inlet temperature and the like as a core safety protection condition, and assisting in slope control of the fuel supply and the turbine rotating speed to avoid potential safety hazards caused by working condition mutation. However, when the conventional starting control strategy is actually applied to the EFGT starting working condition, the conventional starting control strategy still has a plurality of defects, namely the problem of thermal-mechanical coupling in the starting stage is difficult to effectively solve, and the specific defects are that firstly, the feedback lag is caused by the mismatch of thermal inertia and power response, the conventional closed loop control cannot achieve the regulation and control rapidity and the operation safety margin, the abnormal rise of the temperature of a combustion side is easily caused, the thermal load risk of a heat exchanger is increased, the service life of the heat exchanger is influenced, secondly, the abrupt increase of the transient temperature difference of the wall of the heat exchanger is caused in the flow establishing process, the adverse thermal stress impact is caused, the risks of low cycle fatigue, coating damage and sealing failure of a connecting part of the heat exchanger are further improved, thirdly, an active control mechanism which takes the temperature change rate of the wall temperature difference and the wall thickness direction as core constraint is not suitable for the unsteady characteristics of biomass fuel combustion, the generation of transient thermal stress and local hot spots cannot be timely restrained, and finally the stress state of key components such as a tube plate, sealing structure and the tube plate of the heat exchanger are easily damaged, the equipment is seriously damaged, and even the serious problems such as leakage and performance attenuation are caused. Disclosure of Invention The invention aims to provide an indirect combustion type biomass gas turbine starting method, which can realize the time sequence matching between the establishment of a working medium flow field and the temperature rise of a thermal field in the starting process, and effectively restrict the equal amount of wall temperature change rate an