SU1326836A1 - Boiler - Google Patents

Abstract

The invention relates to the field of energy and provides an increase in the efficiency of the boiler by improving the quality of cleaning the air preheater. The boiler contains a furnace, a tubular air heater with a bypass duct, a bypass air duct connecting the duct of a cold air heater with a bypass duct. Means are installed in the boiler for taking flue gases from the boiler furnace with supplying them to the cold air duct and a system for periodically supplying water to the cold air duct, which ensures thermal destruction of the deposit. Research Institute and improves the quality of cleaning. 2 hp f-ly, 1 ill. with GS O5 OO OO a

Description

The invention relates to the energy sector and can be used in various industries of the national economy.

The purpose of the invention is to increase the efficiency of the boiler by improving the quality of cleaning the air preheater.

Sufficiency of the invention consists in increasing the temperature of the pipe wall of the low-temperature part of the air heater by reducing the air supply to it with simultaneous supply of flue gases taken from the boiler furnace and periodically moistening the gas-air mixture, at which the thermal destruction of deposits takes place.

The drawing shows a convective flue gas boiler.

The flue gases 1 enter the high-temperature 2 and low-temperature 3 parts of the air preheater. The recirculation exhaust fan 4 and pipe 5 serve to supply flue gases from the boiler furnace to the air duct 6. Fan 7 serves to supply air, pump 8 to supply water for humidification of the gas-air mixture. Through the conduit 9, the air is supplied to the high-temperature portion and through the conduit 10 hot air flows into the boiler burners. The change in the air and flue gas flow rates is made by the gates 11-15, the water flow is changed by the valve 16, and through the pipeline 17 the gas-air mixture has eaten the low-temperature part is discharged into the boiler furnace.

The cleaning of the air preheater is performed as follows.

When the boiler is working, when the surface of the heater is not cleaned, air is blown by fan 7 through duct 6 first to the low temperature part 3 of the air heater, then to the high temperature part 2 air heater and then through pipe 10 to the boiler burner. In this mode of operation of the boiler, recirculation fan 4 and pump 8 are turned off, no flue gases from the furnace and water are supplied to the duct 6, the gate valves 11, 12, 14 and the valves 16 are in the closed position, and the gate valves 13 and 15 are open. The second mode of operation of the boiler, when cleaning of the low-temperature part 3 of the air preheater occurs. Before the start of cleaning, the recycling exhauster 4 is turned on, the pump 8, the valve 17 is opened and the gate 11, 12, 14, the gate 15 closes, and the gate 13 also is in the open position. The amount of air passed through the low-temperature part 3 and the high-temperature part 2 of the preheater is controlled by acting on the gate 12 and 13. After mixing with the flue gases and moistening with water through the duct 6, the air is supplied to the low-temperature part 3

five

0

five

0

five

0

five

0

heater, then through the pipeline 17 is sent to the boiler furnace, and the other part (the main air flow) through the duct 9 is fed into the high-temperature part 2 of the air heater and after heating it enters the boiler burner. A gas-air mixture moistened with water is fed to the low-temperature part of air preheater 3 every 20-24 hours 20-30 minutes. During the cleaning period (20–30 min), periodic heating and cooling of the pipes is carried out, for which water is fed into the gas – air mixture for 1–2 min at intervals of 10–15 min.

The working medium washes the surface of the pipes outside, i.e., from the air side, where the surface is relatively clean (there are no gold deposits), which ensures a high rate of heating of the pipe walls, due to the high thermal conductivity of the metal compared to ash deposits. At the same time, the dusty flue gases move inside the pipes, therefore two-sided heating of the pipes is provided. The efficiency and reliability of cleaning the heat transfer surfaces of the failures is primarily determined by the thermal effect of the destruction of these deposits, which in turn depends on the wall temperature and the temperature difference between the inner and outer surfaces of the deposits. Mixing air with high-temperature gases taken from the furnace of the boiler allows maintaining a sufficiently high temperature of the gas-air mixture and, therefore, heating the walls of the air preheater to much higher temperatures than during heating with exhaust gases from the inside of the pipes. The temperature difference between the inner and outer surfaces of the deposits significantly increases the thermal effect of the destruction of the deposits. In addition, by periodically supplying water at intervals of 10-15 minutes to the gas-air mixture, a sharp short-term decrease in the mixture temperature is achieved, which in turn creates a variable temperature field on the surface of the air preheater pipes. Thus, the temperature of the pipe wall is variable and the presence of a temperature gradient over the thickness of the sediments significantly increases the thermal effect of the sediment destruction and the efficiency of cleaning the air preheater surface from contamination.

The efficiency of the boiler operation of the proposed design is improved by improving the quality of cleaning the heater air heater, as well as due to the fact that the gas-air mixture after the low-temperature part of the air heater is directed into the boiler furnace and is not released into the environment.

Claims (3)

1. A boiler containing a furnace, a tubular air heater with a bypass duct with a damper, a bypass air duct with a damper connecting the cold air duct of the air heater with a bypass duct, characterized by the fact that it improves the quality of cleaning of the air heater Equipped with a means for collecting flue gases from boiler furnaces and a pipe connected to it with a valve for supplying flue gases to the cold air duct. 2. A boiler according to claim 1, characterized in that it is provided with a periodic feeding system water in the cold air box. 3. A boiler according to Claim 2, characterized in that the periodic water supply system includes a pump and a pipeline connected at one end to the pump and the other to a cold air duct. MEMBERS To burned / am / YU FROM the boiler furnace Air f-t 6 13 sixteen eight To Diposos (/