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  • Jul
    07
    What are SCR and SNCR denitration in circulating fluidized bed coal-fired boilers?
    Reply: SCR is the abbreviation of Selective Catalytic Reduction. Under the action of catalyst, NOx in flue gas is reduced to N2 and H2O by injecting ammonia.The main components of the catalyst are TiO2 and V2O5.SNCR is the abbreviation of selective non-catalytic reduction. The reducing agent containing NH3 group is sprayed into the furnace temperature range of 800-950 ℃, and the reducing agent is rapidly thermally decomposed into NH3, which can be directly reacted with NOx in flue gas without catalyst catalysis. The reaction produces N2
  • Jul
    07
    What matters should be paid attention to in the selection of welding materials for boilers and pressure vessels?
    1. Welding materials for welding pressure vessels include electrodes, wires, steel strips, fluxes, gases, electrodes and gaskets.2. Selection principle of welding materials: According to the chemical composition, mechanical properties and welding performance of the base metal, and combined with the structural characteristics, operating conditions, welding methods and manufacturing processes of the pressure vessel, the welding materials are selected comprehensively, for example: ① Stress and pressure welding For joints, firstly, the welding materials should be selected according to the principle of joint strength; ②For the welding structure working at low temperature, the low-temperature toughness of each area of ​​the joint should be ensured first, which is more important than the strength of the joint; ③For containers with only corrosion tendency, first ensure the container Corrosion resistance of the parts where the inner wall is in contact with the medium; ④ Secondly, consider the processing technology of the welded structure, such as shearing, cold stamping, cold coiling, hot coiling and the influence of various heat treatment processes on the joint performance (cold stamping, shearing and cooling Coiling and other processes require welding joints to have high plastic deformation capacity; while hot coiling and heat treatment processes require joints
  • Jul
    07
    What is the difference between normalizing heat treatment and normalizing rolling of Q345R steel plate?
    ①Normalizing is a method of metal heat treatment. It heats the steel to a certain temperature and keeps it warm, and then cools it in the air to obtain a heat treatment process that is close to a balanced structure. The function is to improve the mechanical properties of the steel.②The normalizing heat treatment of Q345R steel plate is to heat the steel plate to a temperature slightly higher than the Ac3 transformation point (usually the temperature is 890℃~950℃) after the steel plate is rolled, stay at this temperature for a short time and then cool it in still air.Normalizing rolling of Q345R steel plate is a rolling method of rolling at normalizing temperature (generally, rolling starts at 1100℃~1200℃, and the final deformation is controlled above 850℃), which can make the state of the material and the specified value of mechanical properties. Same as normalizing heat treatment.③ Therefore, normalizing rolling actually obtains the microstructure and mechanical properties of normalizing heat treatment through precise temperature-controlled rolling (including final rolling deformation).
  • Jul
    07
    Where is the phenomenon of boiler steam with water?What is the specific reason?
    The phenomenon of boiler steam with water is a normal phenomenon in steam boilers.According to the provisions of JB/T10094 "General Technical Conditions for Industrial Boilers", the steam humidity of saturated steam boilers is not more than 3%, which is qualified, but the excessive amount of water must be treated.If the following phenomenon occurs, it should be caused by excessive steaming water.The boiler feed water volume is much larger than the boiler outlet steam volume, the boiler feed water pump is fully open at the power frequency, the boiler water level continues to drop, a large amount of water flows out of the trap at the sub-drum, and the steam pipeline vibrates in severe cases.Cause analysis: ① Check whether the device in the pot (steam-water separator) is manufactured incorrectly.② Check whether the boiler water is qualified (whether the salt content of the boiler water exceeds the standard).③ Check the operation record of the boiler and understand the steam usage of the owner, whether there is excessive fluctuation in the compliance of steam usage and sudden surge in load.④Whether the water level of the boiler is normal, and the water level of the boiler is kept too high.Beyond the allowable variation range, the accident state false water level.2. WNS
  • Jul
    01
    What are the advantages and disadvantages of single-impulse water level adjustment and three-impulse water level adjustment?
    The single-impulse water level automatic adjustment system is the simplest adjustment method. It adjusts the opening of the feed water control valve according to the water level deviation of the steam drum.The advantage is that the adjustment is simple, and only one water level signal is used as the adjustment amount.The main disadvantage of the single-impulse water level adjustment method is that when the evaporation or steam pressure changes suddenly, the steam content in the boiler water will change rapidly, resulting in a false water level in the boiler drum, resulting in misadjustment of the feed water control valve.Therefore, single-impulse regulation is generally used for small-capacity boilers with relatively stable loads.The three-impulse water level automatic adjustment system is a relatively complete adjustment method. In addition to the drum water level signal, the system also includes steam flow and feed water flow.The water level of the steam drum is the main signal; the steam flow rate is the feedforward signal. Due to the existence of the feedforward signal, it can effectively prevent the malfunction of the regulator caused by "false water level", and improve the adjustment quality under the disturbance of evaporation or steam pressure. ; The feed water flow signal is the feedback signal of the medium, which can overcome the feed water
  • Jul
    01
    What is single-impulse adjustment and three-impulse adjustment of boiler water level?
    In the process of boiler water level control, the adjustment method in which the drum water level is used as the feedback signal is called the single-impulse adjustment of the boiler water level.Single-impulse water level control is the simplest and most basic form of automatic control of boiler drum water level.The three-impulse water level adjustment is in the process of automatic water level control, according to the three impulses of the drum water level, feed water flow, and steam flow through PID calculation to adjust the opening of the feed water valve, so as to achieve the purpose of automatic control of the feed water flow.Three-impulse regulation is actually a cascade control system with a feedforward signal.The liquid level controller and the flow controller constitute a cascade control system.Drum level is the primary variable and feed water flow is the secondary variable.The introduction of secondary variables enables the system to have a strong ability to overcome fluctuations in feedwater pressure (flow).The signal of the steam flow is introduced as a feedforward signal.Because the fluctuation of the steam flow is a factor that causes the change of the liquid level in the steam drum, it is a disturbance effect. When the steam flow fluctuates, it is introduced by measuring
  • Jul
    01
    Oven Precautions
    1. Oven time and temperature control points are different due to different refractory materials and metal heating surface materials. It should be carried out in strict accordance with the heating curve of the oven. The temperature should be raised slowly, and the flame distribution should be uniform.For example, the oven temperature of high-strength wear-resistant castables in a circulating fluidized bed boiler can be referred to as follows: temperature range (℃) rise (decrease) temperature speed (℃/h) required time (h) normal temperature ~ 1505 ~ 1013 ~ 26150± 5024150~31510~1511~16.5315±5036315~54020~257.5~9540±5024540-Normal temperature<25/2. During the oven, the boiler water level should be kept normal, and the expansion of the boiler drum and each header should be monitored and recorded.
  • Jul
    01
    Operation steps of the oven
    1. Turn on the induced draft fan to discharge the gas from the furnace; spread the prepared firewood and base material, with a thickness of about 250 mm, and then ignite it with a torch. At the beginning, the ventilation volume should be small, and the fire should be carried out according to the requirements of the heating curve. Turn on the induced draft fan to make the flue gas flow slowly, increase the rotational speed of the induced draft fan in the middle and late stages, and heat up according to the oven curve.2. Oven standard: based on the moisture content of the brick wall.When the refractory brick mortar moisture content of the furnace wall reaches about 7%, and the red brick mortar reaches 7-10%, it is possible to start the furnace without baking the furnace separately. After the furnace is finished, the moisture content of the furnace wall mortar is below 2.5%. Oven finished.
  • Jul
    01
    The conditions that the oven must have
    1. The boiler body is installed, the furnace wall and insulation work are completed, and the natural maintenance is 5-7 days; 2. The trial operation of each boiler system is completed; 3. The thermal instruments and measuring points required for the oven have been installed and calibrated; 4. Prepare enough fuel for the oven (such as firewood, bottom material, carbon block); 5. Contact the steam turbine personnel to fill the boiler with water to ensure that the water level is at the normal water level.6. After inspection by the testing department, the hydraulic test is qualified.
  • Jul
    01
    Purpose of the oven
    In order to ensure the reliability of each part of the furnace wall of the boiler and long-term use at different temperatures, gradually evaporate the water, and ensure the strength and airtightness of the furnace wall, the newly installed boiler and the newly built furnace wall are naturally cured. , the oven must be carried out.The oven process is actually two stages, namely the natural drying stage during construction and the heating and baking stage.
  • Jun
    22
    Hancheng Thermal Power Co., Ltd. 2x116MW corner tube boiler
    Project address: Hancheng
    Equipment model: DHL116-1.6/130/70-P
  • Jun
    22
    Kunming Xunhechuan Mining Co., Ltd. QCF32.4-1300-23-4.2
    Project address: Kunming
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