Circulating air type ash blocking preventing device and rotary air preheater

Abstract

The invention discloses a circulating air type ash blocking preventing device and a rotary air preheater. The circulating air type ash blocking preventing device comprises a circulating air bin, a circulating draught fan, a conveying pipe, a grinding bin and a control unit, wherein the upper end of the circulating air bin is a hot end, and the lower end of the circulating air bin is a cold end; an upper air channel is connected to the outside of the hot end of the circulating air bin, and a lower air channel which is connected with an air outlet of the circulating draught fan is connected to the outside of the cold end of the circulating air bin; the upper air channel is connected with an air inlet of the circulating draught fan; the conveying pipe communicates with the lower air channel; a grinding solenoid valve which is mounted on the conveying pipe is arranged at a discharging port of the grinding bin; a control end of the grinding solenoid valve is connected with a control unit. The rotary air preheater is provided with the abovementioned circulating air type ash blocking preventing device. The circulating air type ash blocking preventing device influences the smoke exhausting temperature a little, and does not influence the primary air, the secondary air and the smoke; the grinding sweeping mode shows good effect on sweeping an intermediate temperature area of a heat storing plate; the damage of NH4HSO can be effectively solved, and the quantity of air leaking in smoke as well as the air leakage rate can be reduced.

Description

technical field [0001] The invention relates to the structural improvement of a rotary air preheater used in the field of thermal power, and specifically discloses a circulating wind anti-clogging ash device and a rotary air preheater. Background technique [0002] There are two types of air preheaters widely used in power plant boilers: tubular air preheaters and rotary air preheaters. The rotary air preheater is divided into two types: heating surface rotation and wind cover rotation. With the SCR / SNCR flue gas denitrification system put into use and the national pollutant discharge policy becoming stricter, due to the 3 The dust accumulation and corrosion of the rotary air preheater caused by the escape rate exceeding the standard and the burning of high-sulfur coal are relatively common. Precautionary measures such as air heaters, hot air recirculation, and dual-medium soot blowing are widely used in power plants, but there are problems such as the increase in exhaust ...

AI Technical Summary

Problems solved by technology

In order to meet the sufficient air supply volume, the load of the fan increases and the power consumption increases, which increases the operating cost of the power plant. When the resistance of the flue reaches a certain level, the load of the fan may be insufficient and the boiler cannot operate at full load.

(2) Affect heat transfer efficiency and increase exhaust gas temperature

When ash accumulates on the surface of the heat storage element, since the thermal conductivity of the ash is much smaller than that of the metal heat storage plate, it will affect the heat exchange between the flue gas fluid and the heat storage plate. When the gap of the heat storage plate in a certain area is completely blocked , the heat storage plate in this area does not participate in heat exchange at all, so that the heat exchange area of ​​the entire air preheater is reduced, the heat exchange efficiency is reduced, the exhaust gas temperature is increased, the exhaust gas loss of the boiler is increased, and the thermal efficiency is reduced

(3) Aggravate corrosion

For the heat storage element of the air preheater, corrosion and ash deposition are often accompanied. When the air preheater is ash-deposited, it is easier to absorb sulfuric acid vapor and NH4HSO4 in the flue gas. "Hotbed", thus aggravating corrosion and affecting the service life of the heat storage plate

(4) Furnace pressure fluctuates greatly

The ash blocking of the air preheater generally starts from a certain area, and the heat storage element is rotating, which causes the continuous movement of the ash blocking area and the constant change of the resistance of the air flue, which leads to the fluctuation of the boiler furnace pressure and directly affects the furnace. Stability and economy of internal fuel combustion

(5) Increased air leakage

After the air preheater is blocked by dust, due to the increase of resistance, the pressure difference between the fluid medium on the flue gas side and the air side increases, which makes the air leakage problem of the air preheater more serious

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