JPS6053242B2 - Water hammer prevention type waste heat recovery boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiler device that prevents water hammer in an energy saver, and particularly to a device that can be suitably implemented as a waste heat recovery boiler.

Waste heat recovery boilers, which recover various types of waste heat as steam, have been attracting attention as part of recent energy conservation measures.

Because the power-generating waste heat recovery boiler uses waste heat, its startup and shutdown depend on the equipment that serves as the heat source, so startup and shutdown are often performed. In addition, as a means to enable rapid startup, instead of stopping the boiler completely, an intermediate stop state (in which warm water is stored in the boiler in preparation for the next startup) is used.
(hereinafter referred to as "packing"). In a boiler with economizer heat exchanger tubes installed vertically above and below, the generated steam stays in the upper header. When the boiler drum is filled with water in order to restart the boiler in this state, the steam causes the feed water to flow discontinuously through the economizer, giving a severe impact and causing what is called water hammer. In this case, water hammer can be prevented to some extent by lowering the flow rate of the feed water, but rapid startup of the boiler becomes impossible.
Steam is also extracted from the upper header of the economizer, but it is impossible to extract it completely. In addition, in order to prevent steaming inside the economizer, a pipe that connects the economizer and the boiler drum may be provided with a pipe that recirculates a portion of the water supplied at the outlet of the economizer. In this case, the accumulated steam will flow through this pipe.

For this reason, the indication of the flow meter provided in this conduit fluctuates drastically, making it impossible to control the amount of bypass. An object of the present invention is to eliminate the above-mentioned problems and to provide a boiler device in which water hammer does not occur when restarting the boiler after boiler banking is stopped.

In short, this invention connects the lower part of the economizer and the downcomer pipe, and by arranging a valve in this conduit, the boiler drum and the economizer are communicated with each other during packing. This invention relates to a boiler that prevents steam from forming inside the boiler.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a economizer, and heat transfer tubes constituting the economizer are erected in the direction of gravity. Drain pipes 30 are connected to the economizer lower header 1a connected to the lower end of each heat transfer tube, and each drain pipe 30
merges into the main drain pipe 31. Reference numerals 6, 7, and 8 are piston valves provided in these drain pipes that perform two operations: opening and closing. Further, 16, 17, and 18 are drain valves. Reference numerals 9, 10, 11, 12, and 13 are drain valves for discharging the water in the economizer 1 and the water supply pipe 32 to the outside, and the drain valves 16, 17, 18 are used during boiler operation and during puncture. It is also fully closed to increase safety. 19 is a drain funnel into which these drains flow.

Next, a main communication pipe 33 is connected to the downcomer pipe 5 via a drain valve 15, and further this main communication pipe 33 is connected to the valve 1.
The main drain pipe 31 is
is connected to. On the other hand, the economizer 1 and the drum 2 are connected by an economizer outlet line 35, and a recirculation line 36 for preventing steaming of the economizer is connected to the outlet line 35. 3 is a flow meter provided in the same pipe, and 4 is a flow rate control valve.

Reference numerals 20, 21, and 22 are air vent valves provided in the upper header 1b of the economizer. In the above device, during normal operation of the boiler, the piston valves 6, 7, 8 and other valves 9
, 10, 11, 12, 13, 14, 16, 17, and 18 are also fully closed.

As a result, the water supplied from the water supply pipe 32 is transferred to the energy saver 1.
After passing through and being heated to a predetermined temperature, the steam S flows into the drum 2 through the outlet pipe 35, and the generated steam S flows into a superheater (not shown). During this time, if there is a risk that steaming may occur in the economizer, adjust the valve 4 to bypass a portion of the water supply in the outlet pipe 35 to increase the flow rate of the water supply inside the economizer and keep the water supply at a predetermined temperature. to hold. Next, we will explain how to operate when puncturing.

．． During puncturing, water is filled until the drum level reaches its maximum level in order to maintain the boiler in a hot can state so that the next startup can be performed quickly. That is, during the water filling operation, the piston valves 6, 7, and 8 are kept fully closed as in normal operation, and the water is routed through the water supply pipe so that the water does not flow into the main drain pipe 31 side. 32, economizer 1, feeding drum 2 via outlet line 35. In this state, when the drum level reaches its maximum, the water supply is stopped and pumping begins. If it becomes punching, valve 14
, piston valves 6, 7, 8, and drain valves 16, 17, 18 are fully opened.

Thereby, the drum 2 and the economizer 1 are brought into communication via the downcomer pipe 5, the main communication pipe 33, the sub communication pipe 34, the main drain pipe 31, and each drain pipe 30. In other words, these pipes
The drum 2 and the economizer 1 are placed at both ends to serve as a U-shaped conduit. For this reason, the drum 2 and the economizer 1 are in communication with each other, and a head difference H1 occurs, so that only the supplied water is stored in the economizer 1, and no steam retention area is generated. Furthermore, because of this head difference H1, steam does not flow backward from the drum 2. . In addition, if steam is generated in the economizer due to self-flushing of water supply B, etc., the vent valve 20,
21 and 22 are opened to exhaust steam. Of course, in this case, since there is a head difference H2 between the recirculation pipe 36 and the drum 2, only the supplied water stays in the recirculation pipe 36. Next, when puncturing is canceled and the boiler is started, the piston valves 6, 7, and 8 are fully closed, and similarly, the valve 14 and the drain valves 16, 17, and 18 are fully closed before starting.

Subsequently, water is supplied to the drum 2 via the economizer 1 in order to restore the level of the drum 2 that has fallen during puncturing. In this case, water hammer does not occur because there is no steam retention area within the economizer. Furthermore, since no steam flows into the recirculation pipe 36, subsequent recirculation amount control can be performed normally. When the drum level reaches the appropriate value, normal operation begins. Note that the communication valves 6, 7, and 8 also serve as drain valves for the economizer, so when it is desired to drain the water supplied in the economizer, the communication valves 6, 7, and 8 are opened.

Of course, in this case, the drain valve 12 and the like are also opened. By implementing this invention, during puncturing, the boiler drum and the economizer are communicated through a connecting pipe, and the interior of the economizer is constantly filled with water only due to the head difference between the boiler drum and the economizer. Since no steam accumulation occurs, water hammer does not occur when the boiler is restarted.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a waste heat recovery boiler according to the present invention. 1...Coal economizer, 2...Boiler drum,
5... Downpipe, 6, 7, 8... Zestone valve, 30... Drain pipe line, 31... Main drain pipe line, 33...・・Main connection pipe, 34...
... Sub-connection pipe.

Claims (1)

[Claims] 1 In a case where the heat transfer tubes constituting the economizer are installed vertically in the direction of gravity and headers are attached to the upper and lower ends of the heat transfer tubes, the economizer and the boiler drum are connected with a certain head difference, and A water hammer prevention type waste heat recovery boiler characterized in that the lower header of the economizer and the downcomer pipe are connected to each other by pipes each having a piston valve, so that the boiler drum and the economizer are in communication during banking.