JPS5939643B2 - Multi-tubular once-through boiler - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an arrangement in which an upper header that connects the upper end of the heating tube group and a lower header that connects the lower end of the group of heating tubes in the boiler body are connected to a steam separator outside the boiler body through a connecting pipe. Regarding multi-tubular once-through boilers.

In general, the water supply system for this type of multi-tubular once-through boiler separates steam and water from a water supply pump that is controlled by a water level detector in a water column pipe installed in a connecting pipe that externally communicates both headers located above and below the combustion chamber. Water was supplied directly to the lower pipe header below the water level of the vessel.

For this reason, the amount of hot water returned (circulated amount) from the steam separator is small, and the amount of heat absorbed by the inflow water to the lower header fluctuates greatly. The tube wall temperature rises, causing the heating tube to overheat and burn out.

In addition, since the upper portion of the heating tube from the water surface is directly exposed to the combustion gas from immediately after burner ignition to when the burner is ignited during boiler on/off control, overheating is inevitable.

Therefore, there was a drawback that the life of the heating tube was shortened.

In view of the above-mentioned circumstances, the present invention provides a means for protecting the heating tube before air-breathing by covering the heating tube with a combustion gas blocking member from the water surface at the time of ignition of the burner, and from immediately after the burner ignition to air-breathing. In order to prevent the heating pipes from overheating during this period and to protect the heating pipes after aeration, a water supply pipe is opened in the steam chamber of the steam separator, and the steam and water mixture introduced from the upper pipe header into the same steam chamber is By supplying hot water to the lower header together with hot water separated from the air-water mixture heated by cyclone mixing with the feed water, and keeping the heat absorption of the water flowing into the lower header almost constant, By preventing heating tubes from being overheated and burnt out due to scale adhesion due to fluctuations in heat absorption, the heating tubes are protected throughout the boiler operation, whether before or after the heat buildup, thereby extending the lifespan of the heating tubes. The aim is to provide a once-through boiler.

An embodiment of the present invention will be described below with reference to the drawings.A boiler main body 2 has a burner 1 mounted downward on its top surface, and around the combustion chamber 3, two rows of four groups of upright heating tubes are arranged. The lower end is connected to a semi-cylindrical annular upper header 5 and a lower header 6, the upper header 5 is connected to the side of the steam chamber 9 of the steam water separator 8 by a cyclone pipe 7, and the lower header 6 is connected to a return pipe. 10 is connected to the lower end of the water storage chamber 11 of the steam/water separator 8.

As shown in FIG. 3, the steam/water separator 8 of this embodiment is connected to a water supply pump 14 through a connecting pipe 13 to an upper cylinder of an inner cylinder 12 for extracting dry steam and deaerated dissolved oxygen to the load side. A ring-shaped water supply pipe 15 is arranged, and a large number of throttle holes 16 are bored in the surface facing the upper lid, and the upper lid 17 and the steam cylinder 18 are used as water sprinkling plates to atomize the water supply inside the steam chamber 9. .

In addition, a control water level 2 is provided at the upper part of the water column pipe 21 that communicates with the steam chamber 9 and water storage chamber 11 of the steam separator 8 through the communication pipes 19 and 20.
2. A water level detector 23 is attached to the heating tube 4, which controls the pump by detecting the upper and lower limits of the water level (same level as the water level in the heating tube when the burner is ignited). The upper pipe header 5 is also covered with a combustion gas blocking member such as a refractory material 24.

Since this embodiment has the above-mentioned configuration, the water surface of the heating tube 4 when the burner is ignited is located at the area where the refractory material 24 is covered at the upper part of the heating tube, so that heating by the combustion gas is possible from immediately after the burner ignition until the time of extinguishing. There is no overheating of the tubes and therefore there is less localized or concentrated precipitation of scale within the tubes.

Therefore, during the atmosphere, the inside of the heating tube 4 boils and generates bubbles, and the water level appears to be lower than before the atmosphere, but the water level detector 230 that controls the pump always controls the water level. Since the above-mentioned apparent water level is at a position considerably higher than the water level at the previous control water level, the can water circulation force becomes large due to this positional water head.

On the other hand, all the supplied water is introduced into the steam chamber 9 of the steam-water separator 8, and is ejected from the throttle hole 16 of the water supply pipe 15 to the upper cover 17 and the steam barrel 1.
8 is used as a water sprinkling plate to scatter as thin ice particles, and these ice particles are heated and degassed by cyclone mixing with the air-water mixture ejected from the cyclone tube 7, and heated as return water together with the hot water separated from the air-water mixture. It is supplied to tube 4.

Therefore, the amount of heat absorbed by the water flowing into the heating tube is approximately constant, and scale adhesion due to local concentration of can water hardly occurs.

The dry steam and degassed dissolved oxygen produced by separating hot water from the steam/water mixture are taken out of the inner cylinder 12 at a slow flow rate to the outside of the steam/water mixture in the steam chamber. Prevents entrainment or contamination of moisture.

As is clear from the above explanation, in the present invention, since the heating tube is covered with a combustion gas blocking member from the water surface point upward when the burner is ignited, the combustion gas is Overheating of the heating tube is eliminated, and localized or concentrated precipitation of scale inside the tube is reduced.

In addition, since water is supplied to the steam chamber of the steam separator, the amount of heat absorbed by the water flowing into the heating tube is approximately constant after the air is released, and there is almost no scale adhesion due to local concentration of the water in the can.
It is possible to prevent overheating and burnout of the heating tube due to scale.

Therefore, it is possible to protect the heating tubes throughout the boiler operation, whether before or after the boiler is in use, and thus it is possible to provide a once-through boiler with a long heating tube life.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially cutaway side view, Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, and Fig. 3 is a view of air-water separation. It is a longitudinal cross-sectional view of the vessel. 1... Burner, 2... Boiler body, 3...
Combustion chamber, 4... Heating tube, 5... Upper header, 6... Lower header, 7... Cyclone pipe, 8... ...Steam water separator, 9...
Steam room, 10...Return pipe, 11...Water storage chamber, 12...Inner cylinder, 14...Water pump, 15... Ring-shaped water supply pipe, 16...
...Aperture hole, 21...Water column pipe 22...
Control water level, 23... Water level detector, 24... Fireproof material.

Claims (1)

[Claims] 1. In a multi-tubular once-through boiler in which an upper header that connects the upper end of a group of heating tubes and a lower header that connects a lower end of a group of heating tubes in the boiler body are connected to a steam water separator outside the boiler body by a connecting pipe, the steam water A multi-tube once-through boiler, characterized in that a water supply pipe is opened in the steam chamber of the separator, and the heating pipe is covered with a combustion gas blocking member above the water surface at the time of burner ignition.