JP2003322304A - Boiler having water supply starting level differentiated depending on combustion amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration of equipment in a short period of time due to short cycles from starting to stopping a water supply device. <P>SOLUTION: This boiler comprises a combustor 6 changeable in combustion amount, a water level detector 1 for detecting a water level in the boiler, the water supply device 5 for supplying boiler water into the boiler, and an operation control device 8 for controlling the operation of the boiler. The operation control device 8 for starting water supply when the water level drops down to a water supply starting level and for stopping the water supply when the water level rises up to a water supply stopping level controls the generation amount of vapor while regulating the combustion amount of the combustor 6. The water supply starting level in the case of an increasing combustion amount is lower than the water supply starting level in the case of a decreasing combustion amount, and a water level difference between the water supply starting level and the water supply stopping level in the case of the increasing combustion amount is greater than the water level difference between the water supply starting level and the water supply stopping level in the case of the decreasing combustion amount. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler in which the water supply start water level is changed according to the amount of combustion.

[0002]

2. Description of the Related Art A once-through boiler, which is constructed by a pipe and which feeds water from one end and takes out steam from the other end, is widely used. In the case of a once-through boiler, air bubbles are generated in the can water in the heating heat transfer tube, and boiling water is generated in the can water boiling in the heat transfer tube, and the can water is lifted. Set in the middle of the heat transfer tube. The canned water that came up with the steam is separated by the steam separator, but when the boiler water level becomes too high and the boiling amount of the canned water increases, the liquid content cannot be separated from the steam and contains the liquid content. Steam will be taken out. Also, the liquid component separated by the steam separator is returned to the lower part of the boiler, but when the boiler water level becomes too low and the boiling amount of can water decreases, the circulation of can water in the boiler decreases, There are adverse effects such as uneven water quality and temperature of the canned water and partial corrosion. Therefore, it is important to control the water level, and a water level detector connected to each of the steam part and the can water part of the boiler is installed to detect the presence or absence of water at the upper and lower limit positions of the water level, and the water level drops to the lower limit position. Then, the water supply is started, and when the water level rises to the upper limit water level due to the water supply, the water supply is stopped.

FIG. 3 shows the water level of a boiler for performing combustion control at three positions of high combustion, low combustion, and stop, and the operating condition of a water supply device. When the boiler is in a state of high combustion or low combustion, the boiler water evaporates in the boiler, so the water level in the boiler decreases when the operation of the water supply device is stopped. When the operation of the water supply device is started, even if the boiler is burning, the increase in the amount of canned water by the water supply device is larger than the decrease in the amount of canned water due to evaporation, so the water level in the boiler rises.

In a boiler in which combustion control is performed at three positions of high combustion, low combustion, and stop, high combustion, which has a large combustion amount, produces a larger amount of steam. Therefore, when high combustion and low combustion are compared, When the water supply device operates, the water level rises slowly and the water level decreases rapidly when the water supply device is stopped.On the contrary, in the case of low combustion, the water level rises quickly when the water supply device operates and the water level decreases when the water supply device stops. Become slow. In Fig. 3, high combustion and low combustion are extracted for the same amount of time, but since the rate of decrease in the boiler water level during high combustion is high, the number of times of water supply during low combustion is 2 The number of times of water supply is 4 times, and the frequency of starting and stopping the water supply is higher during high combustion than during low combustion. In a once-through boiler that has a small amount of water, it is necessary to repeatedly start and stop the water supply in a short time to maintain the water level in a narrow range. Will be invited.

[0005]

The problem to be solved by the present invention is to prevent the equipment from deteriorating in a short period of time due to the short start / stop cycle of the water supply device.

[0006]

The invention described in claim 1 is a boiler for heating while maintaining the water level in the boiler within a narrow range, and a combustion device and a boiler water level capable of changing the combustion amount are provided. A water level detection device that detects water, a water supply device that supplies canned water into the boiler, and an operation control device that controls the operation of the boiler are provided in advance, and the operation control device determines that the water level detected by the water level detection device is the water supply start water level. When it detects that the water level has dropped to the water level, it starts water supply, and when it detects that the water level has risen to the water supply stop level, water supply is stopped, and the amount of steam generated is controlled by adjusting the combustion amount of the combustion device. Yes,
The water supply start water level when the combustion amount is increased is
When the combustion amount is low, it is lower than the water supply start water level, and when the combustion amount is high, the water level difference between the water supply start water level and the water supply stop water level is calculated as the water level between the water supply start water level and the water supply stop water level when the combustion amount is low. It is characterized by making it larger than the difference.

According to a second aspect of the present invention, in the boiler in which the water supply start water level is changed according to the combustion amount, the operation control device sets the combustion amount of the combustion device to three positions of high combustion, low combustion and stop. It is controlled by the
The first electrode rod that detects the water supply stop water level, the second electrode rod and the third electrode rod that detect the water supply start water level that is lower than the water supply stop water level are provided, and the water level detection position of the third electrode rod is the second. It is set lower than the water level detection position of the electrode rod, water is supplied until the first electrode rod detects the presence of water after the third electrode rod detects the absence of water during high combustion, and the second electrode rod during low combustion. Is characterized in that water is supplied from when the absence of water is detected until the first electrode bar detects the presence of water.

The water supply stop water level is constant, and when the water supply start water level during high combustion is lower than the water supply start water level during low combustion, the water level difference between the water supply start water level and the water supply stop water level increases during high combustion. Therefore, the time from the start of water supply to the stop of water supply and the time from the stop of water supply to the start of the next water supply become long, and the frequency of operating the water supply device decreases, so the equipment It is possible to prevent deterioration in a short period of time.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of a boiler for carrying out the present invention,
FIG. 2 is an explanatory view of a water supply device operating state when the present invention is implemented. The boiler has a combustion chamber 2 in the center, and the periphery of the combustion chamber 2 is surrounded by a number of vertical heat transfer tubes 7. The upper and lower sides of the heat transfer tube 7 are connected to an upper header and a lower header.
A combustion device 6 that controls combustion at three positions of high combustion, low combustion, and stop is provided above the combustion chamber 2, and the heat transfer tube 7 is heated by burning the flame in the combustion chamber.

Water is supplied to the boiler through a water supply pipe 4 connected to the lower part of the boiler, and a water supply device 5 is provided in the middle of the water supply pipe 4. A steam separator 9 is connected to the upper header, and steam generated in the boiler is separated into a gas and a liquid by the steam separator 9, and only steam having a high degree of dryness is taken out. The steam taken out from the steam separator 9 is sent to a steam using unit (not shown) through the steam pipe 10. The steam pressure detecting device 3 is provided in the steam pipe 10 to detect the steam pressure supplied to the steam using unit.

The water level in the boiler is detected by the water level detecting device 1 connected to the upper and lower parts of the boiler. The water level detecting device 1 is provided with three electrode rods having different lower end positions. Each of the electrode rods has a first electrode rod 11, a second electrode rod 12, and a third electrode rod 13 in order from the one having the highest lower end position.
Then, if the lower end of the electrode rod is in water, a current flows, and the water level is detected by determining whether the water level is above or below the lower end of the electrode rod. First electrode rod 11
Indicates the water supply stop position, the second electrode rod 12 detects the water supply start position during low combustion, and the third electrode rod 13 detects the presence or absence of water at the water supply start position during high combustion.

Operation control of the boiler is performed by an operation control device 8 connected to each of the water level detection device 1, the steam pressure detection device 3, the water supply device 5, and the combustion device 6. The operation control device 8 is
The combustion amount is determined based on the steam pressure value detected by the steam pressure detection device 3. If the vapor pressure detected by the vapor pressure detection device 3 is lower than the set pressure on the low pressure side, high combustion is performed. If the vapor pressure is higher than the set pressure on the high pressure side, combustion is stopped.

The water level control by the operation control device 8 is performed by controlling the operation of the water supply device 5 based on the water level detected by the water level detection device 1. If the water level drops to the water supply start water level due to the generation of steam, the operation of the water supply apparatus 5 is started, and if the water level rises to the water supply stop water level by the operation of the water supply apparatus 5, the operation of the water supply apparatus 5 is stopped. The reference water level for starting the operation of the water supply device 5 is made different depending on the combustion amount of the combustion device 6.

When the combustion amount of the combustion device 6 is high, the water supply device 5 does not operate even if the second electrode rod 12 starts detecting the absence of water, and the third electrode rod 13 detects the absence of water. Then, the operation of the water supply device 5 is started. When the water level rises due to the operation of the water supply device 5 and the first electrode rod 11 detects the presence of water, the operation of the water supply device 5 is stopped. When the combustion amount of the combustion device 6 is low, when the second electrode rod 12 detects the absence of water, the water supply device 5 starts operating, and the operation of the water supply device 5 detects the presence of water. Then, the operation of the water supply device 5 is stopped.

If the water supply stop water level is constant and the water supply start water level during high combustion is lower than the water supply start water level during low combustion, the water level difference between the water supply start water level and the water supply stop water level becomes large during high combustion. Therefore, the time from the start of the water supply to the stop of the water supply and the time from the stop of the water supply to the next start of the water supply become long, and the frequency of operating the water supply device decreases.

In FIGS. 2 and 3, the time period for performing high combustion and the speed at which the water level changes are the same, and the operating conditions of the water supply device 5 are compared in the state where only the water supply start water level is different. In the case of FIG. 2, since the water level difference between the water supply start water level and the water supply stop water level is large during high combustion, the frequency of starting and stopping the water supply device 5 is low. At the time of high combustion in FIG.
It is understood that the water supply device 5 is operated twice at the same time at the time of high combustion in FIG. 2, and the number of times the water supply device 5 is started and stopped is reduced.

The reason why the water supply start water level at the time of high combustion can be made lower than the water supply start water level at the time of low combustion is that the boiling water state in the heat transfer tube 7 is different between high combustion and low combustion. . When the combustion amount is low and the combustion amount is low, the boiling amount of the can water is small. Therefore, when the water level in the boiler is low, the circulation of the can water is small. However, in the case of high combustion, the amount of combustion increases and the boiling of the can water increases, so even if the water level in the boiler is lowered to a relatively low position, circulation of the can water occurs and It is possible to prevent uneven temperature distribution. When the water supply start water level was the same for high combustion and low combustion, the water supply device 5 started and stopped frequently during high combustion, but the water supply start water level during high combustion should be lowered below the normal water supply start water level. Therefore, the frequency of starting and stopping the water supply device 5 at the time of high combustion can be reduced, and the life of the device can be extended. In addition,
Since the water supply stoppage level at the time of high combustion is the same as that of the conventional case, the boiling of canned water at the time of high combustion does not increase and the dryness of steam does not decrease.

Further, to make the water supply start water level during high combustion lower than the water supply start water level during low combustion means to change the viewpoint to make the water supply start water level during low combustion higher than the water supply start water level during high combustion. become.
In the case of low combustion with a small amount of combustion, if the boiler water level becomes low, the circulation of the can water will decrease, but by raising the water supply start water level, it is possible to prevent the boiler water level from becoming low, and the boiling of the can water will rise. It is possible to prevent the reduction of the circulation of the canned water.

[0019]

By implementing the present invention, the frequency of starting and stopping the water supply device can be reduced, and the life of the device can be extended.

[Brief description of drawings]

FIG. 1 is a flow chart of a boiler for carrying out the present invention.

FIG. 2 is an explanatory diagram of a water supply device operating state when the present invention is implemented.

FIG. 3 is an explanatory view of a water supply device operating state in a conventional case.

[Explanation of symbols]

1 Water level detector 2 combustion chamber 3 Steam pressure detector 4 Water supply piping 5 Water supply device 6 Combustion device 7 heat transfer tubes 8 Operation control device 9 steam separator 10 Steam piping 11 First electrode rod 12 Second electrode rod 13 Third electrode rod

Claims (2)

[Claims] 1. A boiler for heating while maintaining the water level in a boiler within a narrow range, a combustion device capable of changing the amount of combustion, a water level detection device for detecting the water level in the boiler, and the supply of can water into the boiler. A water supply device that performs the operation and an operation control device that controls the operation of the boiler are provided, and the operation control device starts water supply when it detects that the water level detected by the water level detection device has dropped to the water supply start water level, and the water supply is started. Water supply is stopped when it detects that the water level has risen to the stop water level, and the amount of steam generated is controlled by adjusting the combustion amount of the combustion device.Starting water supply when the combustion amount is increased. The water level is lower than the water supply start water level when the combustion amount is small, and the water level difference between the water supply start water level and the water supply stop water level when the combustion amount is large is calculated as the water supply start water level when the combustion amount is small. Boiler that makes the water supply start water level different according to the combustion amount, which is characterized by making it larger than the water level difference between the water supply stop level and the water supply stop level. 2. The boiler according to claim 1, wherein the water supply start water level is changed according to the combustion amount, the operation control device comprises:
The combustion amount of the combustion device is controlled at three positions: high combustion, low combustion, and stop. The water level detection device uses the first electrode rod that detects the water supply stop water level and the water level lower than the water supply stop water level. A second electrode rod and a third electrode rod for detecting a certain water supply start water level are provided, the water level detection position of the third electrode rod is set lower than the water level detection position of the second electrode rod, and the third electrode rod is used during high combustion. Water is supplied from when the first electrode bar detects the presence of water until the first electrode bar detects the presence of water, and when the second electrode bar detects the absence of water during low combustion, the first electrode bar supplies water until the first electrode bar detects the presence of water. A boiler that varies the starting water level according to the amount of combustion.