Temperature estimate method by measuring the width of Precipitates Free Zone ( PFZ) was applied to the waste tube of low alloy steel (STBA24) used in thermal power plant boiler superheater, reheater, etc., to ensure the possibility of temperature estimate. Also, residual life assessment method by using estimated temperature and measured corrosion rates was developed.

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Low grade coal accounts for the half of total coal resources in the world and super high moisture coal with the moisture content higher than 50% is one kind of it. When such super high moisture coal is applied to conventional USC boilers, the shortage of mill drying capacity and the decline of ignitability and combustibility caused by the decrease of oxygen concentration in burner zones and the increase of moisture content of coal particles are the main concerns. In this research, grinding test and combustion test using super high moisture coal were carried out. And the stable grinding conditions for preventing particles adhesion in mills under high humid atmosphere, and the stable combustion under low oxygen concentration in primary air were verified. These results enabled to utilize low grade and super high moisture coal in conventional USC boilers.

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Coal is one of the widely abundant and highly demanded energy resources. We have developed ultra-low NOx coal firing M-PM burner. Three items of low NOx concepts were proposed based on our operation experience of various low NOx burners and simulation technology which has exceedingly improved recently. Our state-of-the art low NOx concept consists of enhanced ignition due to good mixing of pulverized coal and primary air and wide ignition points, low oxygen combustion by flame holding at the flame inside, and controlling oxygen concentration at outer circumference of the flame by secondary air injection from adequate location. M-PM burner designed according to these concepts was validated with the 4t/h single burner firing test furnace. NOx was successfully reduced by 20-40%, and unburned carbon was reduced by 25-50% comparing with original A-PM burner. NOx emission was between 50 and 110 ppm at the actual 4 unit (350-700MW, bituminous coal) installed M-PM burner and AA nozzle after retrofitting.

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Toshiba has developed and applied the optimal startup methodology to overseas power plants and domestic power plants to match the needs shortening of the startup time of a steam turbine generator. Toshiba reports the optimal startup methodology and some experiences at the commissioning stage in the domestic power plants.

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In the Hamaoka nuclear power plant, when the microbe adhered on the sea water heat exchanger tube of a reactor building closed cooling sea water system, the phenomenon to which heat exchanger entrance difference pressure rises for a short period of time occurred. For this reason, a measure for difference pressure rise control was desired. Then, as a result of doing a model test paying attention to practical use of gaseous microbubble water, CO₂ acquired the prospect of being effective to adhesion control and removal of the adhered microbe. It was based on these results and the verification examination was done.

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TEPCO has been introducing sub-bituminous coal as an economical fuel at Hitachinaka thermal power station, in addition to the bituminous coal that has been used for a long time.This approach has created a new problem in that wastewater from the flue-gas desulfurization facility causes rapid decrease in the Flux of the wastewater treatment filter. This article shows the result of the cause investigation.

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Pipes used in power plants are usually thermally insulated and protected by cover sheet. Numerical simulation and measurement carried out in this study showed that by using an optimized probe which is of small footprint and be able to induce strong eddy currents, pulsed eddy current testing (PECT) was able to detect 30% wall thinning occurred in the inner side of a 11mm thick carbon steel pipe, over a 65mm thick insulation layer. The feasibility of PECT for the inspection of wall thinning was verified.

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A crystal orientation analysis method for visualizing microscopic deformation in metal crystal has been established. This method is used for gas turbine blade materials for which it is difficult to assess degradation and damage. Applying this method, the cause of cracking in actual damaged blades has been clarified. Furthermore, the remaining lifespan from distinct striped patterns observed on the cross section of the cracked surface has been assessed.

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High temperature tensile properties of two nickel-based superalloys, Alloy 740H and Alloy 617, were investigated for evaluating its reliability as a component material of advanced ultrasupercritical (A-USC) power plants. Tensile tests with various strain rates were conducted at 700 °C and 800 °C, and effects of the strain rate and temperature on tensile property were discussed. In addition, influence of the notch on tensile deformation and fracture was presented using circumferential notched specimen.

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Serious heat transfer troubles caused by deposition of powder scale on the surface of boiler tubes have been reported for coal-fired power plants applying CWT in Japan. In order to decrease the amount of iron oxide powder scale carried into the boiler though the low pressure heater drainage, iron removal efficiency of a filter, which can be applied at a high temperature up to 140 degrees Celsius, was investigated. The results obtained in this study suggest that the following advantages are expected by applying this filter to the drainage from low-pressure heater: Reduction of time required for the start-up operation of the coal-fired power plant by lowering the iron concentration in the condensate recovered into the low-pressure heater. Reduction of the amount of iron oxide powder scale carried into the boiler by removing the iron that is contained at high concentration in the low-pressure heater drainage.

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In thermal power plants using Oxygenated feed-water Treatment (OT), the operation of Condensate Polishers (CP) for ion exchange resins is limited to the way in hydrogen form in order to produce highly-pure boiler feed-water.
On the other hand, as recent improvement in resin regeneration technique enable CP operation even in ammonia form to produce high-purity water, it is possible that the ammonia form of CP operation is to be applied to the power plant using OT. We have carried out a field trial to operate CP in ammonia form in an OT plant based on experience and knowledge from our previous studies. This paper shows the results obtained from the filed trial.

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In order to reduce maintenance costs of De-NOx catalyst in the Hekinan Power Station, we determined the deterioration cause of the catalyst performance. And then, we considered the application of recovering catalyst performance with chemical cleaning. As a result, it was confirmed that chemical cleaning by sodium fluoride is effective in recovering catalyst performance.

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