Gasification unit, gasification unit control device and method, and integrated gasification combined cycle

Abstract

A gasification unit includes a gasifier configured to gasify a carbon-containing solid fuel; a pressure vessel housing the gasification furnace; a pressure holding section that is to be filled with a pressurizing gas and is provided between the gasifier and the pressure vessel; a pressurizing gas supply device configured to supply a pressurizing gas to the pressure holding section; pressure equalizing pipes by which the inside of the gasifier is communicated with the pressure holding section; a pressure difference detection and estimation device configured to detect or estimate a pressure difference between a first pressure on the gasifier side and a second pressure on the pressure holding section side; and a control device configured to control the pressurizing gas supply device such that the second pressure is higher than the first pressure based on a detection or estimation result of the pressure difference detection and estimation device.

1 . A gasification unit comprising:
 a gasifier configured to gasify carbonaceous feedstock;   a pressure vessel housing the gasifier;   a pressure holding section to be filled with a pressurizing gas, the pressure holding section being provided between the gasifier and the pressure vessel;   a pressurizing gas supply device configured to supply a pressurizing gas to the pressure holding section;   pressure equalizing pipes by which the inside of the gasifier is communicated with the pressure holding section:   a pressure difference detection and estimation device configured to detect or estimate a first pressure difference between a first pressure on the gasifier side and a second pressure on the pressure holding section side; and   a control device configured to control the pressurizing gas supply device such that the second pressure is higher than the first pressure based on a detection result or an estimation result of the pressure difference detection and estimation device.   
     
     
         2 . The gasification unit according to  claim 1 , wherein the pressure difference detection and estimation device includes a first pressure sensor provided apart from the pressure equalizing pipes in a gas flow direction to detect the first pressure in the gasifier, a second pressure sensor provided apart from the pressure equalizing pipes in the gas flow direction to detect the second pressure in the pressure holding section, and a calculator configured to calculate the first pressure difference from a detection value of the first pressure sensor and a detection value of the second pressure sensor. 
     
     
         3 . The gasification unit according to  claim 1 , wherein
 the pressure difference detection and estimation device detects or estimates a second pressure difference between a thud pressure on an opening of the pressure equalizing pipe on the gasifier side and a fourth pressure on an opening of the pressure equalizing pipe on the pressure holding section side, and   the control device controls the pressurizing gas supply device such that the fourth pressure is higher than the thud pressure based on a detection result or an estimation result of the pressure difference detection and estimation device.   
     
     
         4 . The gasification unit according to  claim 3 , comprising a heat exchanger arranged in a vertically upper part of the gasifier, wherein
 the pressure equalizing pipes are arranged vertically above the heat exchanger,   the pressure difference detection and estimation device includes a third pressure sensor configured to detect the third pressure, a fourth pressure sensor configured to detect the fourth pressure, and a calculator configured to calculate the second pressure difference from a detection value of the third pressure sensor and a detection value of the fourth pressure sensor, and   the control device controls the pressurizing gas supply device such that the second pressure difference is a lower limit value with a tolerance set in advance added or more.   
     
     
         5 . The gasification unit according to  claim 4 , wherein the third pressure sensor and the fourth pressure sensor are arranged at a same height position. 
     
     
         6 . The gasification unit according to  claim 1 , wherein
 a supply amount of the pressurizing gas is controlled as the sum of a standard supply amount and a fluctuating supply amount, the standard supply amount being set such that the first pressure difference is a certain pressure difference or more, the certain pressure difference providing a pressure difference at a normal situation during normal rated operation, and   the control device calculates the fluctuating supply amount to be additionally supplied at a pressure rising rate of the second pressure detected by the second pressure sensor in the pressure holding section.   
     
     
         7 . The gasification unit according to  claim 1 , wherein a supply position of the pressurizing gas to the pressure holding section by the pressurizing gas supply device is a position apart from the pressure equalizing pipes vertically downward by a certain distance. 
     
     
         8 . The gasification unit according to  claim 1 , wherein
 the pressure difference detection and estimation device includes a first pressure sensor provided apart from the pressure equalizing pipes in a gas flow direction to detect a first pressure in the gasifier, a second pressure sensor provided apart from the pressure equalizing pipes in the gas flow direction to detect a second pressure in the pressure holding section, and a calculator configured to calculate a second pressure difference from a detection value of the first pressure sensor and a detection value of the second pressure sensor, and   the control deuce controls the pressurizing gas supply device such that the second pressure difference is an upper limit value set based on a furnace wall strength of the gasifier or less.   
     
     
         9 . The gasification unit according to  claim 3 , wherein
 the pressure difference detection and estimation device includes a first pressure sensor configured to detect a first pressure, a second pressure sensor configured to detect a second pressure in a lower part of the pressure holding section, and an estimator configured to estimate the second pressure difference from a detection value of the first pressure sensor, a detection value of the second pressure sensor, and a height position of the pressure equalizing pipes, and   the control device controls the pressurizing gas supply device such that the second pressure difference is maintained within a certain range set in advance.   
     
     
         10 . The gasification unit according to  claim 1 , wherein
 the pressure difference detection and estimation device includes a fuel flow sensor configured to detect a fuel flow to be supplied to the gasifier and an estimator configured to estimate a pressure in the gasifier based on a detection value of the fuel flow sensor to estimate the first pressure difference, and   the control device controls the pressurizing gas supply device such that the first pressure difference is maintained within a certain range set in advance.   
     
     
         11 . The gasification unit according to  claim 1 , wherein
 the pressure difference detection and estimation device includes a pressure sensor configured lo detect a pressure in the gasifier and an estimator configured to calculate a furnace pressure rising rate of the gasifier based on a detection value of the pressure sensor to estimate the first pressure difference, and   the control device controls the pressurizing gas supply device such that the first pressure difference is maintained within a certain range set in advance.   
     
     
         12 . The gasification unit according to  claim 1 , wherein
 the pressure difference detection and estimation device includes a calculator configured to calculate the first pressure difference in accordance with a load change of the gasifier at start-up set m advance, and   the control device controls the pressurizing gas supply device such that the first pressure difference is maintained within a certain range set in advance.   
     
     
         13 . A control device for a gasification unit that includes
 a gasifier configured to gasify a carbon-containing fuel,   a pressure vessel housing the gasifier,   a pressure holding section to be filled with a pressurizing gas, the pressure holding section being provided between the gasifier and the pressure vessel,   a pressurizing gas supply device configured to supply a pressurizing gas to the pressure holding section, and   pressure equalizing pipes by which the inside of the gasifier is communicated with the pressure holding section,   the control device controlling the pressurizing gas supply device such that a second pressure on the pressure holding section side is higher than a first pressure on the gasifier side.   
     
     
         14 . A control method for a gasification unit that includes
 a gasifier configured to gasify a carbon-containing fuel,   a pressure vessel housing the gasifier,   a pressure holding section to be filled with a pressurizing gas, the pressure holding section being provided between the gasifier and the pressure vessel,   a pressurizing gas supply device configured to supply a pressurizing gas to the pressure holding section, and   pressure equalizing pipes by which the inside of the gasifier is communicated with the pressure holding section, the control method comprising:   detecting or estimating a first pressure difference between a first pressure on the gasifier side and a second pressure on the pressure holding section side; and   controlling the pressurizing gas supply device such that the second pressure is higher than the first pressure.   
     
     
         15 . An integrated gasification combined cycle comprising:
 the gasification unit according to  claim 1  configured to gasify carbonaceous feedstock to generate a combustible gas;   a gas purification unit configured to remove impurities from the combustible gas generated by the gasification unit to perform gas purification;   a gas turbine unit configured to combust a mixed gas of at least part of the combustible gas subjected to gas purification by the gas purification unit and compressed air to rotatingly drive a turbine;   a heat recovery steam generator configured to generate steam by a flue gas from the gas turbine unit; and   a steam turbine unit configured to rotatingly drive a turbine by the steam generated by the heat recovers steam generator.