With the development of gas turbine technology, people have found a way to effectively solve this problem. Using gas turbine combined cycle to utilize waste gas can significantly increase electric power output and increase steam production, while also reducing NOx emissions. The technical transformation route and measures of a steel mill in Italy will be introduced below. 1 general condition of the new device Italy's large steel mill Ilva has several rolling mills in Tarano, one of which was selected as a pilot for power plant retrofits. The rolling mill originally had two steam turbine generator sets in operation. One is the old CET21 installed in the early 1960s with a rated power of 160 MW; the other is the CET22 installed in the 1980s with a rated power of 480 MW. They generate electricity and process steam. The average power supply efficiency is about 36%, which is low. In addition, the boiler can only burn part of the recovered gas. These problems, coupled with the need to reduce NOx emissions from the site and take advantage of the Italian government's tax incentives, have led the mill to replace CET21 with new, more reliable and capacity-packed devices, while modernizing CET22 and continuing to invest. Shipped. The new unit is the M S9001E gas turbine combined cycle unit, named CET23. It is rated at 530 MW, has a total power supply efficiency of 45% and can produce up to 150,000 tons of process steam. The gas turbine not only drives the generator and supplies waste heat to the waste heat boiler to produce steam, but also drives the compressor to pressurize the waste gas to meet the gas turbine combustion requirements. The device was put into operation in 1997. The design of the unit is based on the use of three different sources of waste gas: blast furnace gas having a calorific value of 800 kcal Nm 3 , coke oven gas at 4500 kcal Nm 3 and converter gas at 2100 kcal Nm 3 . In terms of volume, the volume of blast furnace gas is the largest, but the highest calorific value due to nitrogen content. Coke oven gas has the highest calorific value but the smallest volume. The composition and volume of by-product gas are largely affected by the steel production process, and the best conditions occur during the leaching process. Following the Taranto rolling mill, Ilva Steel is modifying its power plant at its second rolling mill in Livorno. As with the Taranto rolling mill, a single 9E combined cycle unit is also used. It is expected to be put into operation in the third quarter of 2000. Both power plant retrofit projects were designed by the new Singapore company. 2 characteristics of the new power unit 211 combustion chamber design The 9E Low Calorific Value Combustion System is the result of years of development of coal and biomass gasification technologies. All 14 combustion chambers on the gas turbine have the same external dimensions as the standard natural gas version, but have been modified to allow dual fuel to operate DD to burn natural gas alone, or to mix natural gas with a variable composition of low calorific value gas. The burner of each combustion chamber consists of an outer ring that burns low calorific value gas and an inner ring that burns natural gas. This combustion chamber can be operated with a mixture of natural gas and waste gas having a calorific value in the range of 1500 to 2000 kcal Nm 3 . The waste gas is first purified during operation and then pressurized to the pressure value required by the gas turbine combustion system. A large amount of dusty impurities in the blast furnace gas and the converter gas and liquid hydrocarbons in the coke oven gas must be removed. The Taranto rolling mill uses a Lurgi filter system based on a wet electrostatic filter. It consists of two converter gas electrostatic filters, three coke oven gas decoking electric filters and a final electrostatic filter for purifying the mixture of three gases. Before coke oven gas is mixed with some converter gas, it must first increase the gas pressure through a booster. In order to improve reliability, both the filter and the blower are arranged in a redundant parallel arrangement to ensure that the waste gas flows into the compressor unit without interruption. 212 fuel gas compression These processes are performed prior to the clean gas entering the fuel gas compressor and gas turbine to prevent damage to components in the kit. A small amount of converter gas does not enter the compressor, but is sent to the waste heat boiler for refueling. The compressor is selected based on two main parameters, the final pressure required to inject fuel into the gas turbine combustor and the volume to be compressed (heat content of the waste gas). Centrifugal compressors are usually used. However, reciprocating compressors can be used in small steel plants. In very large steel mills, axial compressors are used in the initial compression stage, and centrifugal compressors are advantageous later. This is because the gas volume is large in the previous compression. The waste gas mixture enters the combined cycle unit at a pressure close to atmospheric pressure (20-40 m barg) and approximately seven times the volume of natural gas having the same energy. With a three-stage cold compression system, the gas pressure is increased to 22 barg. The compression system is driven by a gas turbine through an upshift gearbox (3000 to 5040 rpm). The compression system performs one stage compression in one cylinder and the remaining two stages in the second cylinder. The Taranto unit has a dual-flow DM CL 1006 low pressure cylinder in which the incoming gas is split into two strands that are drawn in at both ends of the horizontal split cylinder. The gas is compressed from a single outlet in the middle of the cylinder and then cooled. It is sent to the next 2M CL 1007 cylinder, where the gas is pressurized to 8 bar, pumped out for cooling again, and then sent back for final compression to 22 bar. In addition to replacing the DM CL 1006 with a DM CL 1007 compressor, Livinor The same configuration is used in the rolling mill. The pressurization process absorbs about 27 MW of power, but it is possible to recover about two-thirds of the above energy, that is, about 18 MW, by increasing the volume of the gas after it has been expanded by the 9E turbine. 213 single axis sequence The gas turbine generator set, the upshift gearbox and the gas compressor form a five-machine single-axis arrangement of approximately 50 meters in length. The reason why it prefers to use a single-axis solution instead of a motor or steam turbine is because it has better reliability and higher efficiency. For the latter option, the gas compressor will require a large and expensive variable speed motor. In addition, replacing the turbine drive with a gas turbine drive allows full capacity operation even in the event of a steam cycle failure. At the Taranto and Livorno rolling mills, the start of gas turbines is based on the use of natural gas. One reason is that the 22 bar injection pressure is only achieved when the gas turbine and gas compressor are running at full speed. Another reason is that the unit has problems such as ignition and flame and stability below a certain temperature. In the Taranto rolling mill to ensure the performance of the combined cycle, the gas calorific value must meet the following conditions, the calorific value of the gas required for normal operation is 1800kcal Nm 3, 1475kcal Nm 3 is the minimum value to ensure good flame stability, 1975kcal Nm 3 gas Low availability. 214 better performance The rated power of the 9E single-cycle unit operating with natural gas is currently 12314 MW, and the corresponding heat rate is 10653 kJ kW h. The mass flow is 403 kg sec and the exhaust temperature is 594 °C. The rated power of the combined cycle operation designed in the 1×1 mode (ie S109E) is 18,912 MW, and the corresponding heat consumption rate is 6,935 kJ kW h. Earlier, the output of each combined cycle system at the Taranto rolling mill was scheduled to be: 103 MW for gas turbine generators and 68 MW for turbine generators. The total output of all three systems is close to 520 MW. When the gas turbine burns waste gas, A The gas turbine generator supplied by nsaldo has a rated output of 129 MVA at 15 kV. It is cooled by air and the excitation is static. The waste heat boilers of the Taranto and Livorno rolling mills are three-pressure reheating units with refueling facilities. A part of the gas turbine is sent to the non-combustion flue in the upper part of the waste heat boiler, and a part is sent to the lower combustion chamber, and the burner assembly raises the temperature of the flue gas in the superheater and the reheater in the waste heat boiler flue to 540 ° C. 3 process The high pressure portion produces steam having a pressure of 95 to 100 bar and a temperature of 540 ° C; the medium pressure portion with reheating provides steam having a gauge pressure of 25 bar and a temperature of 540 ° C; and the low pressure portion generates saturated steam for the deaerator. The burner for the afterburning of the waste heat boiler was designed at the Genoa test station using waste gas from the ironmaking process for this application. The impulse reaction steam turbine with reheater and condensing unit from Asnaldo has a rated output power of 68 MW. Under normal operating conditions, these steam turbines operate in a sliding manner to keep the intake valve fully open. The exhaust gas is condensed in a two-box, two-channel surface condenser. To enhance the cooling effect, the pumping capacity of the coolant is increased and measures are taken to improve reliability. In addition to the heat generated by conventional combined cycle units, special techniques are employed in the cooling design of the system to accommodate more heat output from the power unit. The main reason is the use of a waste gas cooler. Taranto equipment fulfills this requirement by introducing a valve-type recirculating seawater loop, along with a make-up water facility from the existing working range. If the turbine is shut down, to ensure continued support of the steel plant for electricity and steam, the design provides a bypass valve between the new steam and the cold reheater and between the hot reheater and the condenser. The coal-fired power plant is unchanged, and another gas turbine waste heat boiler system is built. The steam and water supply pipelines are used to connect them with the original steam boiler steam turbine to form a dual-source parallel combined cycle power plant. The dual-source parallel transformation cost is not much, because the original boiler does not make any changes, the new gas turbine waste heat boiler can be positioned and installed relative to the original unit, with little trouble and no adverse effects. A bypass valve and a bypass chimney are installed on the gas turbine exhaust passage, and it can also be operated in a single cycle. The dual-source parallel retrofit cycle is short, and the original unit only needs to be shut down for six weeks in order to connect the supplementary steam line to the turbine and the water supply return line to the condenser water supply heater. The dual-source parallel combined cycle power plant has a very flexible operation mode, which can burn coal and burn natural gas; it can run at the same time and independently of each other, and spare each other. This second transformation route has different plans and will not be described again. In short, when downstream users of natural gas pipelines are building combined cycle power plants, Nanjing Automobile can provide services. 4 Provide reliable spare parts for gas turbines in two stations With its decades of experience in manufacturing turbomachinery, its strong production capacity, the wisdom of hundreds of technicians, and the support of new industrial equipment, Nanjing Auto can provide customers with excellent localized spare parts. . In the future, the spare parts of hundreds of gas turbine units on natural gas pipelines will cost hundreds of millions of dollars each year if they all rely on imports. Based on domestic and domestically produced production methods, the cost of replacing parts will be greatly reduced, and at the same time, the level of domestic manufacturing will be improved. For customers, saving time and tariffs, reducing downtime and increasing availability at both stations. In the future, spare parts must be based on domestic production, and Nanjing Automobile has a unique advantage to become a strong base for providing domestic spare parts for gas turbines. Horn Relay Wiring,4 Pin Horn Relay Wiring,Car Horn Wiring,Horn Button Wiring Taishan Yuanjin Auto Parts CO., LTD , https://www.tsyuanjin.com
Large steel mills produce large amounts of waste gas during the production process, including blast furnace gas, coke oven gas and converter gas. Traditionally, these waste gases are vented to the atmosphere, flashed or sent to a boiler for combustion to produce steam for use in processes or to drive turbine generator sets. The disadvantage of this type of disposal is that the energy contained in the waste gas is not fully utilized and has a detrimental effect on the environment.