JP2002250503A - Method and device for recovering and supplying high- pressure drain from and to multitubular once-through boiler equipped with economizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive energy conservation and, at the same time, prevent the breakage of an economizer by water hammers at the time of recovering and supplying high-pressure drains from and to a multipipe once-through boiler equipped with the economizer. SOLUTION: In a method of recovering and supplying high-pressure drain from and to multipipe once-through boiler, a high-pressure high-temperature drain overflowing the steam separator 30 of the multipipe once-through boiler 10 equipped with the economizer 12 is once stored in a high-pressure drain tank and then is supplied to the economizer 12. The drain from the drain tank is supplied to the economizer 12 by controlling a high-pressure drain supply open/close valve 16 and a high-pressure drain supply quantity control valve 18 in accordance with burner combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for collecting a high-pressure drain and supplying it to an economizer in a multi-tube once-through boiler provided with an economizer.

[0002]

2. Description of the Related Art Conventionally, there has been known a method of exchanging heat between boiler exhaust gas and combustion air to recover heat and save energy. In this case, the air temperature is high and the NOx
And it was difficult to respond to pollution regulations. Conventionally, high-pressure drain recovery in a multi-tube once-through boiler has been performed only with the configuration of the boiler main body, and installation of an economizer is not generally performed. Therefore, the exhaust gas temperature is high and the energy saving effect is small. For example,
At a boiler steam temperature of 1.2 MPa, the saturation temperature is 190 ° C., and it is difficult to collect heat with the exhaust gas temperature of 200 ° C. or less using only the boiler body.

[0003]

The recovery of high-pressure drain in a boiler is performed by applying pressure to a used condensate drain and supplying high-pressure, high-temperature drain water higher than the atmospheric pressure to the boiler to release heat to the atmosphere. It is a system that reduces energy consumption and saves energy, and is expected to spread in the future. On the other hand, in order to save energy, the boiler exhaust gas temperature is required to be 200 ° C. or less, but in this case, if an economizer is installed to increase the thermal efficiency, the economizer will overheat and generate steam, and the water hammer will damage the economizer. There was a fear.

[0004] The present invention has been made in view of the above points,
An object of the present invention is to provide a high-pressure drain water supply opening / closing valve and a high-pressure drain water supply amount control valve of a high-pressure drain recovery system in a multi-tube once-through boiler with an economizer, by using a multi-stage water supply according to burner combustion (forced water supply for protecting the economizer). It is an object of the present invention to provide a method and an apparatus which save energy by controlling and prevent the economizer from being damaged by a water hammer.

[0005]

In order to achieve the above-mentioned object, a method for recovering and supplying high-pressure drain in a multi-tube once-through boiler with an economizer according to the present invention is provided. After storing the high-pressure high-temperature drain in the high-pressure drain tank once,
In this method, the high-pressure high-temperature drain from a high-pressure drain tank is supplied to the economizer by controlling a high-pressure drain water supply opening / closing valve and a high-pressure drain water supply amount control valve in accordance with burner combustion.

In this method, low-temperature water supply is performed by on-off control, and when the high-temperature water supply is at a high water level and the burner is burning, the water is automatically switched to economizer protection water supply for forcibly supplying water to protect the economizer. Be composed.

Further, in this method, the boiler output is set to 1
00, the water supply by the water supply on-off valve is 140 to 16
0%, for example, 150%, and 70 to 90%, for example, 80% at the time of high combustion of the economizer protection water supply, and 30 to 50%, for example, 40% water supply control at the time of low combustion of the economizer protection water supply. preferable.

The high-pressure drain recovery / supply device in the multi-tube once-through boiler with the economizer according to the present invention includes a high-pressure drain water supply opening / closing valve and a high-pressure drain water supply from the upstream side to the high-pressure drain water supply pipe to the economizer in the multi-tube once-through boiler equipped with the economizer. A quantity control valve is provided in series, a low-temperature water supply pipe equipped with a low-temperature water supply pump is connected in parallel to the high-pressure drain supply pipe, and at least two fuel supply valves are connected in parallel to a burner of the boiler main body. A pressure switch is provided on the conduit or steam separator, a level switch is provided on the water level detection cylinder, and at least two fuel supply valves and a pressure switch can be controlled to a high pressure drain water supply amount control valve via a fuel controller. The level switch is connected to the high-pressure drain water supply opening / closing valve, high-pressure drain water supply amount control valve, and low-temperature water supply pump via the water level controller. It is characterized by connecting a fine water supply pump controllably. In this apparatus, it is preferable that a large number of, for example, six water level control electrodes are attached to the water level detection cylinder.

[0009]

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments at all, and can be implemented with appropriate modifications. FIG. 1 shows an overall flow of a high-pressure drain recovery and supply device in a multi-tube once-through boiler with an economizer according to a first embodiment of the present invention, and FIG. 2 shows a flow of a main part in FIG. Multi-tube once-through boiler 10 is an economizer 1
The high-pressure drain water supply pipe 14 to the economizer 12 is provided with a high-pressure drain water supply opening / closing valve 16 and a high-pressure drain water supply amount control valve 18 in series from the upstream side.

A low-temperature water supply pipe 22 having a low-temperature water supply pump 20 is connected in parallel with the high-pressure drain supply pipe 14, and at least two, for example, two fuel supply valves 26, 28 are connected in parallel. Steam-water conduit 32 between the boiler body and steam-water separator 30
Alternatively, a steam pressure controller such as a pressure switch 34 is provided in the steam / water separator (in the drawing, a steam / water conduit is shown), and a level switch 38 is provided in a water level detection cylinder (water column pipe) 36.
And the like, and two fuel supply valves 26,
28 and a pressure switch 34 are controllably connected to the high-pressure drain water supply control valve 18 via a combustion controller 40, and the level switch 38 is connected to the high-pressure drain water supply opening / closing valve 16 via a water level controller 42. The on-off valve 16, the control valve 18, and the pump 20 are controllably connected to the high-pressure drain water supply amount control valve 18 and the low-temperature water supply pump 20.
44 is a high-pressure drain tank, 46 is a drain pump, 48 is a low-pressure tank, 50 is a primary pressure control valve, 52 is an overflow pipe, and 54 is an overflow valve (high-pressure drain valve).

As an example, six water level control electrodes are attached to the water level detection cylinder 36. These electrodes are as follows from below. B: Low water level cutoff L: Low temperature water supply on (pump) H: Low temperature water supply off (pump) DL: High temperature water supply on (high pressure drain valve) DH: High temperature water supply off (high pressure drain valve) DHH: High water level detection

The electrodes of the multi-tube once-through boiler 10 are turned on and off by detecting a change in the water supply height by electrodes. On the other hand, in burner combustion, three-position control of high combustion, low combustion, and stop is performed by a change in steam pressure. Each does not interlock and performs a separate operation. Therefore, when the water is full, the water supply becomes zero, and the economizer is overheated. In the present invention, even in the case of high water level and no water supply,
At the time of combustion, control for continuously supplying water is performed in accordance with the operation state so that there is no evaporation in the economizer 12 and overheating does not occur.
In order to provide appropriate water supply, supply the appropriate amount of water with standard, high combustion, and low combustion. The water supply is turned off when combustion stops.
Combustion is 3 points as an example, and water supply is 4 points as an example.
Automatically control by switching between multiple points.

The amount of continuous water flow is controlled in accordance with the amount of combustion, and the amount of water supply is controlled, for example, by four points. For example, if the boiler output is 100, the on-off water supply is 150%,
The water supply control is set to 80% during high combustion of the economizer protection supply water and 40% during low combustion of the economizer protection supply water. Here, economizer protection water supply refers to forced water supply to protect the economizer when the boiler water level is high.

Next, an example of the operation will be described. (1) Low-temperature water feed pump 20 (water levels H to L): Initial water injection is performed. At the water level L, the water supply pump 20 is turned on, and at the water level H, the water supply pump 20 is turned off. Since the water supply amount is 150% (the boiler evaporation amount is 100%), the water supply is turned on and off. (2) High-pressure drain water supply on-off valve 16 (water level DL to D
H): Open / close by the water level controller 42 during the drain recovery operation.
At the water level DL, the condition differs depending on the combustion state of the burner 24 at the water level DH. Water supply is 150% (control valve 18 is 15%
0% opening). When the burner is off (non-combustion), the valve 16 is closed on the water level DH and the water supply is turned off. During burner-on (combustion), the valve 16 is opened even on the water level DH. (3) High-pressure drain water supply amount control valve 18: The control valve 18 changes when the water level is equal to or higher than DH and combustion occurs. (A) When the water level is equal to or higher than DH and the combustion is high, the opening of the valve 18 is set to 80%. 80% <10
At 0%, the water level drops gradually. When the water level falls to DL, the flow returns to the above (2) and the water supply becomes 150%, and the water level rises. When the water level rises to DH, 80% water is supplied. (B) When the water level is equal to or higher than DH and the combustion is low, the opening of the valve 18 is set to 40%. 40% water supply, so 40% <50%
The water level gradually falls. When the water level drops to the water level DL, the water level becomes 150% and the water level rises. When the water level rises to DH, the water supply is 40%. (C) In non-combustion, when the water level is DH or more, the drain on-off valve 1
6 is closed and the water supply is stopped. These are summarized in Table 1.

[0015]

[Table 1]

(4) Overflow valve 54: The overflow valve 54 opens when the water level reaches the high water level of DHH.

[0017]

As described above, the present invention has the following effects. (1) In high pressure drain recovery and supply in a multi-tube once-through boiler equipped with an economizer, energy can be saved and the economizer can be prevented from being damaged by a water hammer due to steaming due to overheating.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an entire flow of a high-pressure drain recovery and supply device in a multi-tube once-through boiler with an economizer according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a flow of a main part in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multi-tube once-through boiler 12 Economizer 14 High-pressure drain water supply pipe 16 High-pressure drain water supply opening / closing valve 18 High-pressure drain water supply amount control valve 20 Low-temperature water water supply pump 22 Low-temperature water water supply pipe 24 Burner 26, 28 Combustion supply valve 30 Gas-water separator 32 Gas Water conduit 34 Pressure switch 36 Water level detection cylinder 38 Level switch 40 Combustion controller 42 Water level controller 44 High pressure drain tank 46 Drain pump 48 Low pressure tank 50 Primary pressure control valve 52 Overflow pipe 54 Overflow valve (high pressure drain valve)

Claims (5)

[Claims] 1. A method for temporarily storing a high-pressure high-temperature drain overflowing from a steam separator in a multi-tube once-through boiler provided with an economizer in a high-pressure drain tank, and then supplying the high-pressure high-temperature drain to the economizer. A method for recovering and supplying high-pressure drain in a multi-tube once-through boiler with an economizer, wherein the drain is supplied to an economizer by controlling a high-pressure drain water supply opening / closing valve and a high-pressure drain water supply amount control valve according to burner combustion. 2. The low-temperature water supply is performed by on / off control, and when the high-temperature water supply is at a high water level and a burner is burning, the water is automatically switched to an economizer protection water supply for forcibly supplying water to protect the economizer. -Pressure drain recovery and supply method in a multi-tube once-through boiler with economizer. 3. Assuming that the boiler output is 100, the water supply by the water supply on / off valve is 140 to 160%, 70 to 90% at the time of high combustion of the economizer protection flow, and 30 to 50 at the time of low combustion of the economizer protection flow. % Water supply control.
A method for collecting and supplying high-pressure drain in a multi-tube once-through boiler with an economizer as described in the above. 4. A high-pressure drain water supply pipe to an economizer in a multi-tube once-through boiler provided with an economizer, a high-pressure drain water supply opening / closing valve and a high-pressure drain water supply amount control valve are provided in series from the upstream side, and are parallel to the high-pressure drain water supply pipe. A low-temperature water supply pipe equipped with a low-temperature water supply pump, a boiler body with at least two fuel supply valves connected in parallel, a steam switch or a steam separator provided with a pressure switch, and a water level detection cylinder. A level switch, at least two fuel supply valves and a pressure switch are controllably connected to a high-pressure drain water supply amount control valve via a fuel controller, and the level switch is connected to a high-pressure drain via a water level controller. A multi-pipe with an economizer characterized in that the water supply on-off valve, high-pressure drain water supply amount control valve, and low-temperature water supply pump are controllably connected to the on-off valve and water supply pump. High pressure drain recovery and supply device in a flow boiler. 5. The high-pressure drain recovery and supply device in a multi-tube once-through boiler with an economizer according to claim 4, wherein six water level control electrodes are attached to the water level detection cylinder.