JPS59195003A - Method of controlling water level - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a water level control method in a boiler.

In a multi-tube once-through boiler, the liquid level inside the boiler can changes depending on the steam load, and since can water has a high steam content, the water level control device is placed outside the boiler can. Therefore, even if the water level in the water level control device does not change, the liquid level in the boiler can fluctuates because the steam content in the liquid changes depending on the steam load, and when the load is high, the liquid level becomes high.

In order to improve the dryness of the steam under high load conditions, the operating water level should be 60 or higher than the water pipe length. (It is set at a position of about 7%.) When operating at this operating water level, the liquid level in the boiler can will not rise when the load is light, and the water pipes, upper header, etc. will overheat.

In the boiler described above, the present invention can prevent overheating of the upper header, etc., by appropriately changing the average boiler water level according to the steam load ratio, regardless of the steam load ratio. The purpose is to provide equipment.

The present invention includes a boiler steam load measuring device, and a water level control device that increases the operating average boiler water level when the boiler steam load is low and lowers the operating average boiler water level when the steam load is high. It is something.

Examples of the present invention will be described below.

FIG. 1A is a block explanatory diagram showing the configuration of such a boiler system, and a cross section of the boiler is shown. FIG. 1 CB) is a sectional view taken along line A-A in FIG. 1(A).

In the figure, inside the boiler /, a large number of water pipes /-C are installed along the inner peripheral surface of the wall /a, and the water pipes /-D are made of a hollow cylindrical body, and the lower end thereof is an annular lower header. /C (Himuro)
? This, and its upper end is also an annular upper pipe header/
A (steam room) is connected to a hole Zl, and canned water is stored in the lower header 10 and the lower part of the water pipe /b.

The central part of the boiler surrounded by water pipes b is the combustion chamber i.
An air passage th is formed above the air passage th, which communicates with a blower /g driven by an electric motor /f, and a nozzle rod /i and an electrode rod lj are vertically disposed within the air passage /h. be done.

The lower end of the combustion chamber /e communicates with the flue /k through a hollow space between a number of water pipes /b. From the upper header td, a communication pipe 11 extends outside the wall/a and communicates with the lower header/(l).

A water level gauge 1 m for visually displaying the canned water level and a water level detector are installed in the middle of the communication pipe /J. A water supply control section 3 is connected to the water level detection section 2, and its output terminal is connected to an electric motor tIa that drives a water supply pump q. The inlet pipe of the water supply pump communicates with a water source (not shown), and the discharge pipe thereof communicates with the lower header IC.

Additionally, a pressure detection section S is connected to the upper part of the communication pipe /i, and its output terminal is connected to the heating control section B. A control signal line Otsu 1a-AIC extends from the heating control section 6 to a motor /f and an electrode rod /j.

It is connected to each of the fuel pumps 6'd. An inlet pipe of the fuel pump 61CL communicates with a fuel tank (not shown), and a discharge pipe thereof communicates with a nozzle shaft/iJ.

Then, the blow pipe In extends from the lower header IC,
It communicates with a drainage channel (not shown) via a blowcock/p,
A steam pipe /q extends from the upper header td and communicates with a desired steam load (not shown).

In the configuration of the boiler system described above, when generating steam, a blower/g is driven by an electric motor /f to forcefully feed air into the air passage lh, and a high voltage is applied to the electrode rod /j to generate steam through the nozzle rod /g. The fuel injected from the tip of i is ignited and combusted in the combustion chamber le. The high-temperature combustion gas generated by such combustion enters the middle part of the water pipe /b from the lower shoulder end of the combustion chamber /e, passes through it, reaches the flue /k, and is exhausted. During this time, heat exchange takes place and the canned water in the water pipe /b is heated to become steam, which is collected and accumulated in the upper header td and supplied to the steam load through the steam pipe /q.

And heating control? In this regard, the steam pressure in the upper header td is extracted through the communication pipe 11 and supplied to the pressure detection section S, and the pressure detection section S has the steam pressure in the upper header /fi set in advance. When it is detected that the lower steam pressure limit has been reached, a lower steam pressure signal is sent to the heating control section B. Similarly, when it is detected that the upper steam pressure has been reached, the upper steam pressure signal is sent to the heating control section B.

The heating control unit 6 continues to consume steam and the upper header td
When the vapor pressure in the airway drops and a lower limit vapor pressure signal is received, the electric motor /f is started through the control signal line 4 + a, the air passage /h is purged with air using the blower /g, and then the control signal line is A high voltage is applied to the electric rod /j through the nozzle rod 61b, and the fuel pump bId is started through the control signal line AIc to ignite the fuel injected from the nozzle rod 7i to start combustion, and further, When the generation of steam continues and the steam pressure rises, and an upper limit steam pressure signal is received from the pressure detection section S, the fuel pump gld is stopped via the control signal line 41c to cut off the fuel supply, thereby stopping combustion. At the same time, after the combustion gas is discharged, the electric motor /f is stopped via the control signal line b l a and the air blowing from the blower /g is cut off.

Thus, by intermittent control of combustion, the steam pressure in the upper header td can be maintained at a pressure value between the two positive pressure values preset as the upper and lower steam pressure limits.

In addition, in a simple device, electric motor/f, fuel pump 6°d
Start/stop control and application of high voltage to electrode rod /j may be performed simultaneously.

Furthermore, regarding the water supply system, changes in the canned water level in the air-water interface in the communication pipe iJ, that is, in the water pipe /1) are transmitted to the water level detection section -, and the water level detection section detects the canned water level in advance. When it is detected that the set lower limit water level has been reached, it sends a lower limit water level signal to the water supply control section 3.

When the can water level in the water pipe drops due to steam consumption and a lower limit water level signal is received from the water level detector ko, the water supply controller 3 starts the electric motor pa and uses the water feed pump q to send water through the lower pipe header/C. Water supply to water pipe /b is started, water supply continues, the canned water level rises, and after the set time has elapsed by the timer, based on the time-up signal, electric motor Ua is stopped and water supply to water pipe /b is started. cut off.

Thus, by intermittent control of water supply, the can water level in the water pipe/1) can be maintained at a water level value corresponding to a preset steam load.

The intermittent control of water supply and the intermittent control of combustion are performed separately and independently from each other.

Further, when blowing canned water, by opening the blow cock /p, part or all of the canned water in the lower header /C and water pipe /1) can be blown out through the drain pipe In.

In addition, blower/g, air passage/h, nozzle rod/1, electrode rod/
The burner consisting of j is not limited to this, and if necessary, it is sufficient to heat the canned water in the water pipe /b to generate steam, so it generally includes an electric heater, etc. Any heating device may be used.

Similarly, the heating control section 6 may also be of any type as long as it can turn the heating device on and off.

Next, an example of a steam load measuring device according to the present invention will be described. In the present invention, it is not necessary to determine the amount of evaporation; it is only necessary to express the steam load as a percentage of the total load. In addition, even if the steam load is determined as a percentage of the total load, it is not necessarily required to be determined with high accuracy.
It may be a percentage determined approximately. The state of this steam load fluctuation has already been clarified by the inventors, and a measuring device for the heating time and heating stop time has been proposed.
The steam load can be determined by the ratio. FIG. 2 is a control block diagram showing a heating control section, a heating time measuring section, and a heating stop time measuring section.

The pressure sensor 5a outputs a corresponding steam pressure signal SO in response to the steam pressure in the upper header ld led through the communication pipe/work.
) When the vapor pressure is higher than the lower limit vapor pressure PL as shown in a = /, the reference voltage is equal to the lower limit set value of the vapor pressure signal SΩ corresponding to the lower limit vapor pressure PL supplied from the reference voltage source 3eL. (2) Since the vapor pressure signal So becomes larger than L, the first comparator 5b detects this and outputs "l" as shown in FIG. 3(0)b-/.

Then, the steam pressure decreases as the steam is consumed or the temperature decreases, and when it reaches the lower limit steam pressure PL, as shown in Figure 3 (B) C-/, the steam pressure signal SO becomes lower than the reference voltage This is detected and the first comparator 5
b outputs "d" as shown in FIG. 3(C) d-/.

The flip-flop 6' receives the inversion of the output signal of the first comparator 5b from "/" to
b is set to "l", and its positive phase output signal is inverted from "example to figure" as shown in FIG. 3(D) e-/.

Upon receiving this signal, driver B becomes conductive, and relay 1. e is energized, contact Oe l, ,, 6
! +, 60II+ is closed, electric motor/f, electrode rod/
Since power is supplied to the j1 fuel pump gld, the canned water is heated.

During the period when the flip-flop 4b is set to "/", heating continues, and the vapor pressure continues to rise as shown in FIG. 3(A) f-/.

Eventually, as shown in FIG. 3(A) g-t, when the vapor pressure reaches the upper limit vapor pressure PH, the vapor pressure signal So that has been supplied from the reference voltage source 5e corresponds to the upper limit vapor pressure Because it was smaller than the reference voltage vH, which is equal to the upper limit setting value of the vapor pressure signal So, the second comparator SC, which was outputting the same voltage, As shown in i-/, 'd' will be output.

p of the output signal of the second comparator 5C" to "
/'' is reversed from r/J to p'' by inverter Aa.
It is converted into the inverse of , and is supplied to the reset terminal of the flip-flop 6b, which is reset to "sub.".

As shown in FIG. 3 (Dlj-/), the positive phase output signal of the flip-flop 6b becomes "0", so the relay 6e becomes de-energized, and the contacts te', t, e''
4 e Ill is opened and heating of canned water is stopped.

In this way, the time Th+ (hereinafter referred to as heating time) from when the heating device starts until it stops is specified by the time during which the flip-flop 6b is at r/J,
Furthermore, the time Th from when the heating device stops until it starts
2 (hereinafter referred to as heating stop time) is the flip-flop 6
It is specified by the time when "b" becomes "p".

After stopping heating, as shown in Figure 3 (A) ki,
The flip-flop 6b remains at "0" until the steam pressure decreases again as the steam is consumed or the temperature decreases and reaches the lower limit steam pressure PL, forming a heating stop time Thz. The operation is repeated to maintain the vapor pressure between the lower limit vapor pressure PH and the lower limit vapor pressure Pj.

For example, if the amount of evaporation (steam load) increases in the process of increasing steam pressure, the amount of heat flowing out of the boiler system due to evaporation of canned water increases in proportion to the amount of evaporation, so more water is removed from the boiler system. The amount of heat is taken away, and as shown in Figure 3 (
A) As shown in f"-l, the rising gradient of vapor pressure becomes slower.

Now, hypothetically, at the time shown in FIG. 3(A) c-t, at the same time, the flip-flop 6b is inverted to "d" as shown in FIG. 3(E) e'-/ζ. Heating time T
Assuming that the transition has occurred to time h1, if the amount of evaporation increases, at the time shown in FIG. 3(A) g'-/, the flip-flop xb becomes Since the value is reversed to "0", a heating time Th+" is formed which is longer than the heating time Th+ before the amount of evaporation increases.

A quantitative consideration of the change in the heating time Th1 depending on the change in the amount of evaporation is as follows.

In general, changes in internal thermal energy held by a boiler system d
U is (i'[J=ηB-Hu-dt+Gy-Iw-dt-G
s7Is-dt-QH*at...
...Represented by (1).

However, η...Boiler efficiency (excluding heat radiation loss) B...
...Fuel calorific value Hu...Fuel consumption (flow rate) Gw...Water supply amount (flow rate) to the boiler W...
- Enthalpy of water supply G, ... evaporation amount (flow rate), s11... Steam enthalpy QR ..... Heat radiation amount (heat flow rate) of the boiler.

Regarding the right side of equation (1), the first term is the amount of heat flowing into the boiler system due to the heating of canned water, the second term is the amount of heat flowing into the boiler system due to the supply of canned water, and the third term is the amount of heat flowing into the boiler system due to the supply of canned water. The term G represents the amount of heat flowing out of the boiler system due to evaporation, and the term G represents the amount of heat flowing out of the boiler system due to heat radiation.

By the way, in general, in a boiler system, the variable amount of canned water that is replenished by intermittent control of the water supply system is small compared to the amount of canned water held during operation. Therefore, the amount of water held in the boiler system during operation can be considered to be a constant value unique to each boiler system. The internal thermal energy U possessed by the boiler system at the end of the heating time Th1 corresponding to the thermal energy UL and the upper limit steam pressure PH
Each of H is specified to a value unique to each boiler system.

Therefore, based on equation (1), the increase in internal thermal energy (UH-UL) generated in the boiler system with the passage of one heating time Th+ is approximated by:

In reality, the difference between the upper and lower vapor pressure limits PH2PL is not large, so for the sake of simplicity, calculate the average enthalpy value s+n corresponding to the upper and lower vapor pressure limits, and let it be expressed as s-sin.
Equation (2) is r Th + UH-UL: (η・B-Hu) Th1 + engineering wj G
ydt〇-(1n from Gs) Th+-Q, R-Th1"
” ・(3).

Furthermore, considering the heating time Th+, within one heating time Th1, water is supplied a number of times according to the amount of evaporation due to intermittent control of water supply, which is performed independently of heating control. The amount of water supplied (flow rate) that exceeds the amount of evaporation (flow rate) flows into the boiler; on the other hand, during the water supply stop period, water is not supplied at all, and the amount of water supplied (flow rate) that flows into the boiler becomes zero.

However, from a long-term perspective over a large number of heating times, in an operating boiler system, the average water supply amount (flow rate) supplied by water supply control is in equilibrium with the evaporation amount (flow rate), so the amount of water held in the boiler is approximately It is kept at a constant value.

Therefore, fGwat = G3Th1
− − − −(4) holds true.

Then, the evaporation amount GS is obtained from equations (3) and (4).

However, if , and the feed water enthalpy is constant, both are constants unique to each boiler system.

Therefore, in equation (5), (!=C!B-OR...(6) Then, the evaporation amount G8 is It is expressed as

Further, C represents the amount of evaporation when the heating time Th+ is infinite (continuous heating), that is, the maximum amount of evaporation unique to each boiler system.

Therefore, even if the amount of evaporation (steam load) is zero, this heating time T10 is the minimum heating required to maintain the boiler system in an operating state by compensating for the thermal energy that flows out mainly due to heat radiation from the boiler. It's time.

FIG. 3 is a graph illustrating the relationship between the heating time Th1 and the evaporation amount Gs expressed by the equation (7).

In this way, the boiler system heating time Th1 is the evaporation iGS!
Therefore, it is specified as a value unique to each boiler system, so if the heating time Th1 is measured and specified, the above (5) to (
7) The evaporation amount Gs can be calculated according to the formula.

Next, for example, in the process of lowering the vapor pressure, the amount of evaporation (steam load)
When the amount of boiler water increases, the amount of heat flowing out of the boiler system due to evaporation of can water increases in proportion to the amount of evaporation, so as in the process of increasing steam pressure, more heat is taken away from the boiler system. Therefore, Fig. 5 (A) corresponding to Fig. 3
As shown in k'-1, the downward slope of the vapor pressure becomes steeper.

Now, suppose that at the time shown in Fig. 5 (A) g -/l, at the same time, Fig. S (g)) j' -/i is 1 as shown in
Assuming that the flip-flop 6b is also reversed and the transition to the Calothermal stop time occurs, when the evaporation force S increases, at the time shown in FIG. (
As shown in g))m'-/, the flip-flop 6b is reversed to "/", so the heating stop time Thz is shorter than the heating stop time Th2 before the amount of evaporation increases. ' is formed.

A quantitative consideration of the change in the heating stop time Th2 depending on the change in the amount of evaporation is as follows.

During the heating stop time, there is no heating of canned water, the first term on the right side of equation (1) becomes zero, and the change in internal thermal energy key aU is am = GW・WCLt”E3・■6−at−Q,
R, at ...-(9), and the decrease in internal thermal energy (UL - UH) with the passage of one heating stop time Th2 is Th2 UL - UH = = Iv, Layer, Gwdt - (GB・Works, n) Thz-QHTh2----α
It is expressed as ψ.

(L(y1 in formula σTh2 , 0w6-t = GS Thz ・；。

Then, to find the evaporation amount GS, becomes.

However, R ISlr: -Eng.
, ---(/le) and G
B = (Heating stop time T at 7, is, and even if the evaporation amount (steam load) is zero, the heating stop time T20 is the upper limit steam pressure mainly due to the outflow of thermal energy due to heat radiation from the boiler. This is the maximum heating stop time required to reach the lower limit vapor pressure.

Therefore; even when the steam load is no load, the boiler system heating device has a heating time of T10. Intermittent control is performed with heating stop time T2°.

FIG. 6 is a graph illustrating the relationship between the heating stop time Th2 and the evaporation amount Gs expressed by the formula 09.

In this way, the heating stop time Th2 of the boiler system also depends on the evaporation ft
Since it is specified as a value unique to each boiler system according to G5, by measuring the heating stop time Th2 and specifying it, the above I
The evaporation amount Gs can be calculated according to the formula.

Next, return to Figures 2 and 3 and check the Nathermal time measurement section T.
The operations of H/ and heating period calculating section g-/ are as follows.

During intermittent control of the heating device, the positive phase output signal of the flip-flop 4b is, for example, as shown in FIG. 3(D).
It becomes "/" during the heating time Th+.

In response to this positive phase output signal, the AND gate 1) opens and the clock pulse oscillator 7 opens only during the heating period.
The clock pulse from a-7 is guided to Carantuff C-/ and counted.

Then, as shown in FIG. 3(D) j -/, when the flip-flop 6b is inverted from "/" to "O", its positive phase output signal is inverted from "/" to "θ" and the ant game
)'7b-/ is closed and the supply of clock pulses to the counter 7C-/ is cut off, and a digital code representing the heating time Th1 is outputted to the counter 7C-/ as a heating time signal 51-1. Ru.

At the same time, the arithmetic unit ffa-/ receives the inversion of the positive phase output signal of the flip-flop 6b from "/" to "θ" at the control terminal, and executes the arithmetic processing described below.

After the arithmetic processing by the arithmetic unit zaa-/ is completed, the positive phase output signal of the flip-flop xb mentioned above becomes ``/''.
f:, upon reversal to roJ, the monostable multi-nog ibrator 7a was triggered and transitioned to a metastable state.
- / returns to a stable state and the clear pulse is sent to the counter '
Since the counter 7C-/ is sent to the clear terminal of 70-/, the counter 7C-/ is cleared and prepared for the next measurement.

On the other hand, the heating stop time measuring section THj, which has the same configuration as the heating time measuring section TH/, receives a reset signal from the complementary output terminal of the flip-flop Ab, and receives a signal 5 representing the heating stop time Thz.
2-1 is output to the arithmetic unit &a- via the storage device MTH2.
/ is input.

The arithmetic unit ga- is cleared before the counter '/C-/ is cleared.
/ outputs a steam load factor load factor signal 85 from signals 51-1 and 52-1, and sends it to the water supply control section.

FIG. 7 is a block diagram showing a water level detection section and a water supply control section.

When the water level is higher than the lower limit water level, the lower limit water level probe 2a is submerged in water, and the underwater electrode -0 is in a state of constant communication through water, and the current detector 2e, Since a load circuit consisting of the lower limit water level probe 2a1 and the underwater electrode 2C is formed, a current flows through the current detector θ, and upon detecting this, the current detector 2e outputs "/".

Then, when the water level drops and reaches the lower limit water level IJJ,
The tip of the lower limit water level probe 2a leaves the water surface and the load circuit to the AC power supply 2d is cut off, so the current detector 2
The current passing through e becomes zero, and detecting this, the current detector 2e outputs the current.

In response to the inversion of the output signal of the current detector 2e from "/" to "example", the flip-flop 3b changes to "p".
, and its positive phase output signal is inverted from "sub" to "/". Upon receiving this signal, the driver 3C becomes conductive, the relay 3e is excited, the contact 3eI is closed, and power is supplied to the electric motor (la), so canned water is supplied to the boiler.

Thus, water is supplied and the water level continues to rise.

At the same time, the positive phase output of flip-flop 3b becomes "/
'', the AND gate 3f opens and the clock pulse from the clock pulse oscillator 3m is guided to the counter 3g, and counting begins. Then, the load signal S5 from the computing unit ga-/ is input to the computing unit 3h, which calculates the set water supply time corresponding to the load signal s5, and then calculates the set water supply time corresponding to the load signal s5. When the water supply time reaches the set water supply time, a water supply stop signal S6 is output. This water supply stop signal S6 is sent to the flip-flop 3
The positive phase output of the flip-flop 3b is reversed from "L" to "Q", the relay 3e becomes de-energized, the contact 3e'' is opened, and the water supply is stopped.

At the same time, the AND gate 3f closes and the counter 3g stops counting. Subsequently, the water supply stop signal S4 triggers the monostable multi-vibration break 31, which had been in a quasi-stable state, to return to a stable state and send a clear pulse to the counter 3g.
The counter 3g is cleared and prepared for the next water supply time measurement.

Next, to explain the calculation in the calculator 3h to obtain the set water supply time corresponding to the load signal S5, the set water supply time is determined by dividing the coefficient C, which determines its value by the water supply time at the reference steam load rate, by the steam load rate Z. It can be found by calculating.

FIG. 8 is a time chart of the present invention. / is a line indicating 0N-0'E'F of the heating device, ia, ia are computing units,
? Lines indicating the operation of the heating time timer and heating stop time timer in a-/, IS is the line indicating the upper and lower levels of the canned water level, 17
is a line indicating the operation of the lower limit water level probe 2a, it is a line indicating ON/OFF of the water supply pump, and /9 is a line indicating the counter value during the water supply period.

When the pressure decreases due to steam consumption, time! At step 5, the pressure detection section S detects the lower limit steam pressure, and the heating device is turned on. Then, as shown by line 13, the heating time timer starts operating, and at the same time, the heating stop time timer shown by Ml Hiroshi starts operating.
FF. Heating continues until time 26, and at time 26, the pressure detection unit S detects the upper limit steam pressure and operates, the heating device is turned off, and the heating time timer is turned off.
The heating stop timer is turned on. Then, when the pressure decreases due to steam consumption, the pressure detection section S detects the lower limit steam pressure at time 27, and the heating device is turned on. and line 13
As shown in , the heating time timer starts operating, and at the same time, the heating stop time timer shown by line /4' turns OFF. Repeat the same below.

Heating time Th+ and heating stop time T
With h2, Th+/(Th+-1-Th2) is calculated, which value approximately represents the steam load.

The steam load factor between time 2S and time 1 is calculated by the computing unit ra-/ at the time core and is output to the water supply control unit 3. Now, when the water level falls and reaches the lower limit water level probe 2a at time 2g, the water supply pump q becomes operational, and the water supply time counter 3g counts as shown by line 19.

While water is being supplied, the water level rises and the water supply counter value increases. The arithmetic unit 3h constantly compares the set water supply time specified by the steam load signal S inputted to the water supply control unit 3 with the output of the water supply time counter 3g, and as shown at time 29, the output of the water supply time counter 3g is When the set water supply time is reached, the water supply pump stops and the water supply time counter 3
g stops counting and is then cleared.

As the steam load decreases, the amount of evaporation also decreases, so the water level is 13 tons.
As shown in s-t, the gradient of the water level decrease becomes smaller.

As shown from time 3Q to time 32, as the steam load decreases, the heating time Th+ decreases, the heating stop time Th2 increases, and the steam load rate in this section decreases. Therefore, the set water supply time increases, and at time 33, which is the time after time 32, the water level drops to the lower limit water level probe 2a.The water supply time in the water supply operation from time 2g to time 2q increases. It is longer than time,
Water is supplied from time 33 to time 3.

Therefore, the reached can water level at time 3q is higher than the reached can water level at time 29. In this way, in the present invention, the length of one water supply time changes depending on the evaporation load rate, and when the steam load rate is low, the water supply time during 7 ON-OFF periods of the water supply pump changes. The length of time becomes longer and the amount of water supplied increases.

Therefore, the canned water level when the water supply is stopped becomes higher, and accordingly, the average canned water level in each period of ON-OFF of the water supply pump also becomes higher. On the other hand, when the steam load factor is high, the water supply time during the seven 0N-OFF operations of the water supply pump becomes shorter, and therefore the can water level when the water supply is stopped becomes lower. The average can water level in each cycle of ON-OFF of the water supply pump becomes lower.

In the above embodiment, the relationship between the set water supply time and the steam load rate is set as shown in FIG. 2, but the present invention is not limited to the above embodiment.
For example, as shown in FIG. 9Y, it is possible to divide the steam load rate into a high load area, a medium load area, and a low load area, and change the set water supply time in stages. As shown in U, the relationship between the steam load rate and the set water supply time can also be expressed linearly. In normal cases, Figure 9 X, Y
, U in combination as appropriate. For example, in extremely low load areas, the set water supply time is set to a constant value as shown by line Y, and in other load areas, the set water supply time is set to a constant value as shown by line X. It is desirable that the set water supply time also be changed.

In the above explanation, the steam load factor was calculated from the heating time and heating stop time, but the steam load was calculated based on the 0N of the heating device.
- It is not limited to calculation from OFF, and any calculation that can be performed continuously during operation may be used. Note that the water level may be detected by a level switch.

As described above, the present invention allows the canned water level to be adjusted to 0N using the water supply device.
- In the boiler l, which is controlled by turning OFF, the average can water level can be raised or lowered depending on the steam load, and the average can water level can be controlled to a high level when the steam load is small. Overheating of the upper pipe girder, etc. is eliminated.

[Brief explanation of drawings]

Figure 1 (5) is a block diagram showing the configuration of a small boiler system to which the configuration of the present invention can be attached, and Figure 1 (B) is a cross-sectional view of boiler f at A and -A in Figure 1 (A). , second
The figure is a heating control diagram, Figures 3 and 5 are waveform diagrams of the main parts of the heating control section in Figure 2, the second figure is a graph showing the relationship between heating time Th1 and evaporation amount Gs, and Figure 6 is a heating control diagram. Stop time Th
FIG. 2 is a water level control diagram, FIG. g is a time chart of the present invention, and FIG. 9 is a graph showing the relationship between steam load factor and set water supply time. 2a: Lower limit water level detection probe s5: Load factor signal. Patent Applicant Ebara Corporation Agent Arai Partial Figure 1 (E3)

Claims (1)

[Claims] / Water level detection means that detects the canned water level and outputs a lower limit water level signal, and intermittent control that starts a water feed pump that supplies water to the boiler in response to the lower limit water level signal and stops the water pump in response to a timer. In a boiler system equipped with a water supply control means, a means for calculating a steam load factor and a signal from the means for calculating a steam load factor are received, and a set time of the timer is set according to the steam load factor. Water level control method in boiler system.