Heat recovery steam generator and power plant

Abstract

According to the embodiment of the present invention, there are provided a first stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the superheater, a second stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the evaporator, a fuel supply system configured to distribute fuel so as to be supplied to the first stage auxiliary burner and the second stage auxiliary burner. Distribution of fuel charged to each of the first stage auxiliary burner and the second stage auxiliary burner is controlled in accordance with a predetermined distribution ratio of each charging quantity to whole charging quantity in all the range thereof.

1 . A heat recovery steam generator in which a plurality of heat exchangers consisting of a superheater, an evaporator and an economizer are installed in a duct along a flow direction of exhaust gas from a gas turbine, so as to generate steam by utilizing the exhaust gas of the gas turbine, the heat recovery steam generator comprising:
 a first stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the superheater;   a second stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the evaporator;   a fuel supply system configured to distribute fuel so as to be supplied to the first stage auxiliary burner and the second stage auxiliary burner; and   a fuel distribution control means configured to control distribution of fuel charged to each of the first stage auxiliary burner and the second stage auxiliary burner, in accordance with a predetermined distribution ratio of each charging quantity to whole charging quantity in all the range thereof.   
     
     
         2 . The heat recovery steam generator according to  claim 1 , wherein the fuel distribution control means is configured to control distribution of fuel, with increase in steam amount, such that the charging quantity of fuel to the second stage auxiliary burner is increased in the beginning, and after that the charging quantity of fuel to the first stage auxiliary burner is increased. 
     
     
         3 . The heat recovery steam generator according to  claim 2 , wherein the fuel distribution control means is configured to increase the charging quantity of fuel to the second stage auxiliary burner, maintaining the charging quantity to the first stage auxiliary burner at a constant flow rate with pilot flame therein keeping, while the degree of superheating of steam in the superheater is sufficiently high. 
     
     
         4 . A power plant comprising:
 a gas turbine configured to drive a turbine in rotation by combustion gas of high temperature and high pressure;   a heat recovery steam generator in which a plurality of heat exchangers consisting of a superheater, an evaporator and an economizer are installed in a duct along a flow direction of an exhaust gas from the gas turbine, so as to generate steam by utilizing the exhaust gas of the gas turbine;   a steam turbine configured to be driven by the steam generated by the heat recovery steam generator; and   a generator configured to be driven by the gas turbine and the steam turbine;   wherein the heat recovery steam generator includes:   a first stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the superheater;   a second stage auxiliary burner configured to heat up the exhaust gas in the upstream side of the evaporator;   a fuel supply system configured to distribute fuel so as to be supplied to the first stage auxiliary burner and the second stage auxiliary burner; and   a fuel distribution control means configured to control distribution of fuel charged to each of the first stage auxiliary burner and the second stage auxiliary burner, in accordance with a predetermined distribution ratio of each charging quantity to whole charging quantity in all the range thereof.   
     
     
         5 . The power plant according to  claim 4 , wherein the fuel distribution control unit of the heat recovery steam generator is configured to control distribution of fuel, with increase in steam amount, such that the charging quantity of fuel to the second stage auxiliary burner is increased linearly in the beginning, and after that the charging quantity of fuel to the first stage auxiliary burner is increased. 
     
     
         6 . The power plant according to  claim 5 , wherein the fuel distribution control unit of the heat recovery is configured to increase the charging quantity of fuel to the second stage auxiliary burner, maintaining the charging quantity to the first stage auxiliary burner at a constant flow rate with pilot flame therein keeping, while the degree of superheating of steam in the superheater is sufficiently high.