Control method for optimizing generated power of solar-aided coal-fired power system under off-design working conditions

Patent metadata

Field	Value
Publication number	US-11359807-B2
Application number	US-202117598902-A
Country	US
Kind code	B2
Filing date	Jan 25, 2021
Priority date	Feb 19, 2020
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

A control method for optimizing generated power of a solar-aided coal-fired power system under off-design working conditions sets maximizing generated power without changing main steam flow rate as a control goal. A solar-coal feedwater flow distribution ratio is adjusted to adjust water flow rate heated by a solar heat collection system, so as to achieve the control goal. Control steps include reading relevant information; calculating the water flow rate range heated by the solar heat collection system, and an applicable solar-coal feedwater flow distribution ratio range; establishing a correspondence between the generated power and the solar-coal feedwater flow distribution ratio within this range; selecting a solar-coal feedwater flow distribution ratio corresponding to the maximum generated power; and adjusting the water flow rate entering the solar heat collection system to an optimized value. The present invention can flexibly control the solar-coal coupling and improve the economy.

First claim

What is claimed is:

1. A control method for optimizing generated power of a solar-aided coal-fired power system under off-design working conditions, comprising steps of:
setting maximizing the generated power as an optimal control goal; and maximizing the generated power referring that under conditions of keeping a main steam flow rate, a main steam temperature and a reheat steam temperature of a steam turbine of the solar-aided coal-fired power system unchanged, adjusting a solar-coal feedwater flow distribution ratio of a solar-coal complementary loop to adjust a water flow rate heated in a solar heat collection system, thereby maximizing an output power of the steam turbine;
wherein the generated power is obtained by using a formula (1) to calculate a specific enthalpy of water heated by the solar heat collection system and water heated by a high-pressure heater after being mixed, and then by using formula (2) and combining a calculation method for a thermal system under off-design conditions to calculate the generated power;
h w(i−1),in =α TCS ×h s,out +(1−α TCS ) h wi,out   (1)

wherein h w(i−1),in is the specific enthalpy of the water heated by the solar heat collection system and heated by the high-pressure heater after being mixed, i=1, 2, . . . , n, kJ/kg; n is a total number of regenerative heaters in the solar-aided coal-fired power system, and the regenerative heaters are numbered from 1 to n in an order of high pressure to low pressure; α TCS is the solar-coal feedwater flow distribution ratio; h s,out is a specific enthalpy of the water heated by the solar heat collection system, kJ/kg; h wi,out is a specific enthalpy of the water heated by the high-pressure heater, kJ/kg;

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wherein D 0 is the main steam flow rate of the solar-aided coal-fired power system, kg/s; h 0 is a specific enthalpy of main steam of the solar-aided coal-fired power system, kJ/kg; D zr is a reheat steam flow rate of the solar-aided coal-fired power system, kg/s; h zr is a specific enthalpy of reheat steam of the solar-aided coal-fired power system, kJ/kg; D i is an i-th stage extraction steam flow rate of the steam turbine of a coal-fired power generation system in the solar-aided coal-fired power system, kg/s; h wi,in is a specific enthalpy of an i-th stage extraction steam of the steam turbine of the coal-fired power generation system in the solar-aided coal-fired power system, kJ/kg; D c is an exhaust steam flow rate of the solar-aided coal-fired power system, kg/s; h c is a specific enthalpy of exhaust steam of the solar-aided coal-fired power system, kJ/kg; D sg1 and D sg2 are a front shaft seal steam flow rate and a rear shaft seal steam flow rate of the coal-fired power generation system in the solar-aided coal-fired power system, kg/s; h sg1 and h sg2 are specific enthalpies of front shaft seal steam and rear shaft seal steam of the coal-fired power generation system in the solar-aided coal-fired power system, kJ/kg;
the control method for optimizing the generated power comprises specific steps of:
Step 1: obtaining operating conditions required by the solar-aided coal-fired power system, and obtaining relevant information of the solar heat collection system connected in parallel with high-pressure heaters, the coal-fired power generation system, and environmental conditions;
Step 2: determining a water flow rate range heated by a solar heat collection unit according to a heat transfer oil working temperature range and an equipment safe working range of the solar heat collection unit; and then, according to a ratio of the water flow rate range to a feedwater flow rate of the coal-fired power generation system, determining a solar-coal feedwater flow distribution ratio range applicable by the solar-aided coal-fired po

Assignees

• Univ Xi An Jiaotong

Inventors

• Yan Hui
• Chong Daotong
• Li Xin
• Liu Ming
• Yan Junjie

Classifications

• F22D5/26 Primary

  Automatic feed-control systems · CPC title

• F22B1/006

  using solar heat · CPC title

• F03G6/06

  with solar energy concentrating means · CPC title

• F24S50/00 Primary

  Arrangements for controlling solar heat collectors · CPC title

• F24S20/40

  Solar heat collectors combined with other heat sources, e.g. using electrical heating or heat from ambient air · CPC title