KR100914616B1 - Fuel expenses and continus water supply controlling system of industrial boiler - Google Patents

Abstract

A fuel efficiency and continuous water feed control system for an Industrial boiler is provided to reduce the amount of power use because the inverter is consecutively controlled in consideration of the vapor pressure, and the steam temperature and burner part rate. A fuel efficiency and continuous water feed control system for an Industrial boiler comprises a fuel efficiency control unit, five electrode rods, and a continuous water supply unit. The fuel efficiency control unit comprises an oxygen sensor(1) and a MICOM controller(2). The MICOM controller calculates the necessary air volume for the combustion, based on the measurement signal of the amount of oxygen measured by the oxygen sensor. The MICOM controller calculates the blower operation inverter value in order to operate a blower motor(19). In five electrode rods, a contact rod(A) transmits the contact signal to the MICOM controller. A lowest water level sensing electrode rod(B) generates a lowest water level detection signal. A highest water level sensing electrode rod(E) generates a highest water level detection signal. A low limit water level sensing electrode rod(C) generates a signal by detecting an allowable low limit water level. A high limit water level sensing electrode rod(D) generates a signal by detecting an allowable high limit line. The continuous water supply unit changes the driving frequency of the feed pump to supply the necessary amount of water.

Description

Fuel expenses and continus water supply controlling system of industrial boiler

The present invention relates to an industrial boiler using LNG as a fuel, and in particular, to improve the fuel consumption control method and the continuous water supply method to comprehensively determine the correlation between the temperature, pressure and the combustion amount in the pipe, and to calculate the amount of steam consumed based on this. Fuel efficiency control and continuous control of industrial boilers that achieve continuous water supply by detecting the level change to maintain the appropriate level and controlling the head so that the water pump can be operated by operating the water supply inverter based on the signal. A water supply control system.

In boilers used for heating and industrial purposes, water is intermittently or continuously supplied to replenish evaporated steam continuously. In general, intermittent water, which is widely used as a boiler water supply method, is a method of periodically operating a water pump (on-off) based on the detection of an upper and a lower water level using an electrode, and using an electrode and an inverter. There is a method of supplying step by step by inputting a specific frequency. In general, when the intermittent water supply increases, the change in the level of the steam increases, such as the change in the dryness of the steam, the amount of evaporation, and the steam pressure. In order to compensate for this disadvantage, there is a method of continuously controlling the water level using an automatic control (PID) by a level sensor (generally outputting 4 to 20 mA depending on the water level) instead of the electrode. The use of such continuous automatic control results in a lower level of dryness, evaporation, and steam pressure than in intermittent water supply. However, such continuous automatic control requires additional level sensors, automatic control systems, motors with inverters, and the like, so that additional costs are incurred. In particular, since the level sensor is 10 times more expensive than the electrode, the cost is greatly increased.

In order to make up for this drawback, the inventors have developed a system for continuously and automatically controlling the water level using electrodes instead of expensive level sensors. Because of using low-cost electrodes instead of expensive level sensors, the cost of constructing the system is relatively low, and because the boiler level is continuously controlled, the level change is smaller than that of intermittent water supply.

On the other hand, there is an intermittent water supply system shown in Fig. 5 as a conventional method of controlling the water level of the boiler by using an electrode and an inverter.

In the conventional method, the upper and lower level detection electrodes 51 and 52 and the intermediate level detection electrodes 53 are installed in a boiler to install the upper and lower level detection electrodes 51 and the intermediate level detection electrodes. As shown in FIG. 5 as a system for maintaining the water level between 53, when the water level of the boiler reaches the intermediate level detection electrode 53, the pump is driven at the maximum speed to supply the boiler with the fastest water supply. At this time, for example, in the case of an inverter type, the pump is driven at 60 Hz, and when the water level rises as the pump is driven to reach the upper limit level detection electrode 51 and the upper limit level is detected (section a in FIG. 5), For example, if the pump is driven with 60Hz of supply electricity at the initial stage of pump operation, if the pump is operated at the upper limit level, it is reduced to 30Hz to reduce the water supply while greatly reducing the pump driving speed. In this state, since the amount of steam generated in the boiler is greater than the amount of water supply, as shown in section b of FIG. 5, the level of the boiler is gradually lowered, and the intermediate level detecting electrode 53 is lowered again by the level decrease. When the inverter detects, the inverter raises it to 60Hz and drives the pump at high speed so that water can be supplied quickly to the upper limit level. It is that the operation can be repeated.

However, the conventional method of electrode control adopts a passive control method for driving an inverter, and is a square wave form that is periodically turned on and off between 60 Hz and 30 Hz, and requires a lot of pump driving power, evaporation amount, water level and There was a problem that the stability of the system was deteriorated because of the variability in the steam pressure.

Accordingly, the present invention has been proposed in view of the above point, and its object is to calculate the optimum average level value of the target and finely adjust the driving speed of the pump in response to the operating environment of the boiler, thereby reducing the power consumption. It is small and has excellent boiler efficiency and steam dryness, and it produces steam with constant pressure and temperature, supplying steam and supplying water at a uniform speed, extending the life of piping and various instruments, and maintaining boiler system. It is to provide a continuous water supply control system of a boiler with low maintenance cost.

In order to achieve the above object, an oxygen sensor 1 is installed in a boiler exhaust part through which exhaust gas is discharged, and the oxygen amount included in the exhaust part is measured, and a signal for measuring the oxygen amount is input to the microcomputer controller 2 for combustion. Fuel economy control means for driving the blower motor 19 by calculating the air volume and calculating the blower operation inverter value;

A ground rod (A), the lowest level sensing electrode (B), the lowest level sensing electrode (C), the upper limit level sensing electrode (D), and the maximum level sensing electrode (E), each of which is installed in communication with the reservoir of the boiler pipe. Is provided with two electrodes, the ground rod (A) of the five electrodes are connected to the microcomputer controller is installed to transmit a ground signal, the lowest level detection electrode (B) is installed to generate the lowest level detection signal is the electrode level The lower end of the electrode (B) is installed so as to extend to be located at the lowest level of the boiler tube to generate the lowest level detection signal when falling out of the lower end of (B), the maximum level detection to generate a signal by detecting the highest level The electrode (E) is installed such that the bottom of the electrode (E) is located at the maximum level so that the water level rises to generate the highest level detection signal when the bottom of the electrode (E) contacts water. Located between the level and maximum level sensing electrodes (B) and (E), it is allowed to detect the minimum level of acceptable level in the tube and to generate a signal to generate a signal. The upper limit water level detection electrode (D) for generating a signal by detecting the upper limit possible is generated to generate a level detection signal, which is acceptable by the lower limit water level detection electrode (C) and the upper limit water level detection electrode (D). While the upper and lower water level is repeating a certain number of times, the water level fluctuation time is checked in real time, and the average learning value is calculated.The average learning value is used as a reference point. It is characterized in that it is equipped with a continuous water supply device to achieve the required amount of water supply by controlling the lift by changing.

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The present invention as described above is calculated by comparing the water level fluctuation rate with the reference time value and the steam pressure detected from the tube pressure sensor, the steam temperature and burner load rate by the temperature sensor continuously control the inverter device to supply the water feed pump By operating optimally, optimum continuous water supply is possible, and the steam pressure, temperature, and water supply in the pipe are stabilized and power consumption is reduced by improving pump driving efficiency.

In addition, the oxygen sensor hides the amount of oxygen contained in the exhaust gas in real time in real time, inputs the signal to the microcomputer controller, calculates the output signal, and transfers it to the blower inverter to supply as much air as necessary for the combustion amount of each load of the boiler. By replenishing, unnecessary driving of the blower can be eliminated to achieve power savings.

1 is a schematic configuration diagram of a continuous water supply control system of a boiler according to the present invention

Figure 2 is a detailed configuration of the continuous water supply control system of the boiler according to the present invention

Figure 3 is a flow chart for hot water supply control of the boiler by the water level information of the present invention

4 is a flow chart for the hot water supply control of the boiler in consideration of the steam pressure and the boiler load ratio of the present invention

5 is a prior art

[Description of Symbols for Main Parts of Drawing]

 1: boiler 2: burner

 3: water level detector 4: microcomputer controller

 5: oxygen sensor 6: tubular pressure sensor

 7: tube temperature sensor 8: burner load rate detector

 9: water level sensor (water level detection electrode, A, B, C, D, E)

10: analog calculator 11: water supply calculator

12: combustion range control distributor 13: feed water inverter control signal generator

14 Induction Motor Vector Inverter 15 Feed Pump

16: blower inverter control signal generator

17: internal combustion evaporation calculator 18: induction motor vector inverter

19: blower motor hc: low water level

hd: Upper water level h: Water level difference

Hereinafter, with reference to the accompanying drawings of the present invention will be described in detail.

1 is a schematic configuration diagram of a continuous water supply control system of a boiler according to the present invention, and FIG. 2 is a detailed configuration diagram of an in-phase boiler continuous water supply control system.

One side of the boiler (1) is provided with a burner (2) as a heat supply source for heating the water to generate steam, and also a plurality of for detecting the water level in order to adjust the appropriate water level of the boiler (1), the present invention In the embodiment shown in Fig. 5, five electrode rods A, B, C, D and E of different lengths are provided in the water level sensor 3. One of the five electrodes (represented by the symbol 9) is the grounding electrode (A), and the symbol B is the lowest level sensing electrode to detect the lowest level the boiler can accept (if the electrode detects the lowest level, Is to generate an alarm), symbol E is the maximum level sensing electrode to detect the maximum level that the boiler can tolerate (the pump is stopped when the electrode detects the maximum level), and symbols C and D Is the upper and lower limit water level detection electrode (D) (C) for detecting the appropriate upper and lower limits of the boiler.

In the present invention, in controlling the water level of the boiler (1), the water supply is not performed in the maximum and minimum water level section, but through the upper and lower level (hd, hc) sensing electrode rods (D, C) installed therebetween. In the meantime, it aims to maintain the water level. Accordingly, the optimum level is located between the upper and lower limit levels (hd, hc), and the preferred level difference (hd-hc) allowed by the boiler 1 is h.

The water level information detected by the electrode (C) (D) is sent to the microcomputer controller (4), the microcomputer controller (4), in addition to the water level information oxygen sensor (5), tube pressure sensor (6), tube temperature On the basis of various information detected by the detector 7 and the burner load rate detector 8, the information calculated through the analog calculator 10 is applied to control the water supply calculator 11, and the analog calculator 10 is again described above. The information is applied to the water supply amount calculator 11 via the combustion range control distributor 12 and the combustion evaporation amount internal calculator 17 so that the water supply amount calculator 11 receives the water supply inverter control signal generator 13 and the induction motor vector inverter 14. It is configured to drive control the feed water pump (15) via.

The combustion range control distributor 12 controls the blower inverter control signal generator 16 and the induction motor vector inverter 18 to drive control the blower motor 19.

According to the present invention having the above configuration, the oxygen sensor 1 is installed in the boiler exhaust portion through which exhaust gas is discharged, the amount of oxygen contained in the exhaust portion is measured, and the signal is input to the microcontroller 2 to calculate the amount of air suitable for combustion. And a fuel consumption control means for driving the blower motor 3 by calculating a blower operating inverter value, and five electrodes installed in communication with the reservoir of the boiler tube, wherein the ground rod A of the five electrodes It is connected to the microcomputer controller and transmits the signal and is located at the lower side of the tube to be installed to generate the lowest level detection signal, and is installed to generate the signal by detecting the lower limit of the proper level in the tube. The upper limit water level detection electrode rod (C), the upper limit water level detection electrode rod (D) for generating a signal by detecting a proper upper limit line in the tube, and the highest level detection signal are generated. The maximum level sensing electrode (E) is installed separately to generate a level detection signal, and the appropriate level is detected by the lower limit sensing electrode (C) and the upper limit level sensing electrode (D), and the level fluctuation time is checked. Find the optimum level and calculate the steam consumption obtained by comparing the pressure information detected by the pipe pressure sensor (5) with the burner load rate detected by the burner load rate sensor (7) and the temperature detected by the pipe temperature sensor (6). It is equipped with a continuous water supply device to obtain the required water supply, and to deliver it to the water supply inverter to control the head by adjusting and changing the driving frequency of the water supply pump in real time.

In the present invention, when the lower limit water level is detected, the pump is driven at a designed inverter driving value, for example, 60 Hz, and the inverter driving value is gradually considered in consideration of the reaching time of the upper limit water level until the water level rises until the upper limit water level is detected. At the time of reaching the upper limit, the pump drive speed is reduced to the designed inverter drive value, for example 30 Hz (or the pump drive may be stopped, at which point the pump drive speed from maximum to zero is increased). The pumping speed of the pump is increased or decreased in real time between 60Hz and 30Hz in consideration of the rate of water rise according to the concept of time on the way, and if the upper and lower water levels are repeatedly detected for a predetermined time, it takes into account the actual steam usage. Calculate the results in the meantime and store them as learning values The boiler is operating.

Next, the operational flow of the present invention will be described in detail by a flowchart.

3 is a flowchart for controlling the hot water supply of the boiler. When the boiler starts to operate normally, it is determined whether the lower limit water level is detected from the lower limit water level detection electrode C (step (a)). In this step, if the lower limit level sensing electrode C is turned on, it means that the current level is lower than or equal to the lower limit. Therefore, it is necessary to operate the pump 15 at high speed.

Next, in step (b), it is determined whether the upper and lower water level is set or whether the boiler has been operated for a predetermined time, for example, the upper and lower water level is detected 10 times each time, or if the boiler has been operated for 60 minutes. The pump 15 is started to drive at the designed value (C₁Hz), for example 60 Hz.

When the pump 15 is driven, water is supplied to the boiler, so it is detected whether the water level is rising (step (d)). If the water level does not rise or decreases even though the pump 15 is being driven, the amount of steam is high. In this case, after controlling to increase the pump driving speed (step (e)) and returning to step (d), if it is detected that the water level rises, the driving speed of the pump 15 is gradually inversely proportional to the level rise. (Step (bar)), where the rate of water rise is set to 10 minutes as the reference time for the water supply from the lower limit of the boiler to the upper limit. If the rise speed is lower than the design value, if the rising speed is lower than the design value, proceed to step (e) to increase the pump driving speed. Kimyeo controls to ten thousand and one is higher than the design value to delay the driving speed of the pump (step (a)).

In this way, if the speed is equal to the designed value during adjustment, the driving speed of the pump is gradually decreased as designed until the water level reaches the upper limit, and the pump is driven (C₂Hz> C₂Hz) at the upper limit water level (C₁Hz> C₂Hz) (step).

In the next step, it is judged whether the upper limit water level is detected by the upper limit water level detection electrode (D) (step (d)), and if the upper limit level is not detected yet, the process returns to step (c), and if the upper limit water level is detected, Drive the inverter to the design value (C₂Hz) (step (k)).

The next step is to determine whether the water supply is reduced and the level of water is gradually decreasing due to the increase in the amount of steam used (step (ta)). The control is made to pause (step). At this time, if the water level is gradually lowered, the driving speed of the pump is controlled to increase gradually in inverse proportion to the water level lowering (step (lower)), and if the water level lowering speed is a lower limit at the upper limit level in consideration of the design value, for example, the steam usage, If you set 20 minutes as the standard time to decrease to the water level (compared to the fall time), if the water level lowering speed is lower than the design value, the pump operation speed is lowered or stopped because the steam consumption is relatively small compared to the water supply. If the water level descending speed is higher than the design value, the steam consumption is significantly higher than the water supply. Therefore, the driving speed of the pump is controlled to be higher than the design value (step (no)). Return to continue.

However, if the rate of descent matches the design value, gradually increase the pump's drive speed to the designed value until the water level reaches the lower limit, controlling the pump drive to reach C₁Hz at the lower level (step) and again Return to).

In step (b), it is determined whether the upper and lower water level has been detected by the set number of times (or constant operating time of the boiler), for example, the upper and lower water levels are detected five times each, or the boiler is operated for 1 hour as a time unit. In this case, the average driving value is calculated to obtain an inverter driving value, and then the pump driving is controlled based on the learning value (step (ro)).

Next, a process of controlling the pump and the burner in consideration of the steam pressure fluctuation of the boiler and the load factor of the boiler in addition to the water level information will be described by the flowchart of FIG. 4.

Judging whether the lowest level detection electrode B is off (step), if the off state, the boiler water level is currently below the minimum level, and a low level alarm alarm is issued (step). Control the inverter to run at maximum value (step (more)). If the lowest level detection electrode (B) is on, the pump operation is controlled in consideration of the steam pressure. If the steam pressure of the boiler is higher than the designed value, the pumping speed and / or the load factor of the boiler is higher because the amount of steam generated is greater than the used value. Will be controlled to lower.

Accordingly, if the frequency calculation for the pressure is not completed in step (r), it is determined whether the water level is to start continuous water supply (step (mer)) and waits for the water supply stop electrode to be turned on (step (burr)). Stop and return, or return with the feed pump running.

If the water supply start level is reached in the singing phase (mer), it is determined whether the operation is started (step), otherwise it is driven to the maximum value of the water supply inverter (step (low)), and it is determined whether the water supply stop electrode is on. (Step) to stop and return the feed pump inverter if it is on (step) and to return immediately if it is not on.

If operation is started in the step (er), it is determined whether it is the first operation after the stop (step), and if yes, it is determined whether the continuous water supply delay time has exceeded the set value (step). If no, stop and return the feedwater inverter (step); if yes, return immediately.

If it is not the first operation after stopping in the step (fur), it is determined whether the current pressure is higher than the set pressure (step). After (step (2)), the pressure frequency calculation complete (flag 1) (step (lu)) and returns to step (r), if "Yes" in step (nu), the current pressure is subtracted from the set pressure After the frequency variable order is generated (step (no)), the step (r) is returned through the step (ru).

On the other hand, if the frequency calculation for the pressure is completed in the step (r), it is determined whether the combustion state of the current burner is greater than or equal to the set value (step), and if not, the secondary frequency is changed by subtracting the set combustion amount from the current combustion amount. Create an order (step), then update the constant substitution values and inverter control values in the database for the first and second variable orders (step), and if at step " If yes, the second combustion variable order is generated by subtracting the current combustion amount from the set combustion amount (step (Note)) and then proceeding to step (right).

Next, it is determined whether the control electrode is turned on (step), or returns to the initial state. If "yes", the control electrode decreases by the set% value from the current inverter control value (step), and then the pressure frequency. The operation is cleared (flag = 0) (step (ta)) and returned.

The boiler operating system of the present invention as described above is as follows. Table 1 is a diagram showing the relationship between the water level and the inverter value for the pump drive in the automatic control system of the present invention, contrast table 1 shows the relationship between the water level and the inverter value for the pump drive in a simple control system according to the prior art The diagram shown.

Table 2 is a chart showing the relationship between the vapor evaporation amount (L / h, the top graph), the water level (mm), the center graph and the water supply inverter (Hz, bottom graph) in the automatic control system of the present invention, contrast Table 2 is a chart showing the results of the prior art in contrast.

And Table 3 is a table showing the operating time (min), steam pressure (kg / cm², lower graph) and evaporation (L / h, upper graph) of the boiler in the automatic control system of the present invention, contrast Table 3 This is a table showing the results of the prior art in contrast.

Table 1

[Comparative Table 1]

[Table 2]

[Comparison Table 2]

Table 3

[Comparative Table 3]

Table 4

Table 5

As can be seen from the above diagram, in the case of the prior art, the inverter value is a square wave of the ON, OFF method that is repeatedly maintained equally for a certain time, but in the case of the present invention, the inverter value is finely adjusted in real time in consideration of the steam usage, so the average It can be seen that the water level of the boiler is maintained relatively constant compared to the prior art as well as being adjusted up and down according to the learning value as a reference point. Especially, as shown in Tables 2 and 3, about 60 minutes for the boiler load of 60% After the test, the test was performed with the steam flow sensor and the boiler water level sensor signals cut off, and as a result of the test, the evaporation level signal and the boiler water level signal did not come out after about 120 minutes. As it was confirmed, cut off the signal for about 10 minutes and then re-wired to obtain all the signals continuously. In addition, even if the signal is disconnected and reconnected during the operation of the boiler as described above, it can be seen that the water level is normally controlled regardless of this. That is, it can be seen that driving is controlled by past learning values.

On the contrary, in the case of the prior art, it can be seen that the cycle is longer when the boiler load is 60 Hz, and it can be seen that the fluctuation of the vapor evaporation amount, the water level, and the steam pressure is more severe than the present invention.

On the other hand, Table 4 is a graph showing the relationship between the water level and evaporation amount and the water level and the vapor pressure in the automatic control method and the prior art of the present invention, the pink part on the right is the present invention, and the blue part on the left is the conventional method. It can be seen that the automatic control water supply method of the method has a smaller distribution (e.g., a smaller change) of the evaporation amount and the vapor pressure than the conventional method.

In addition, Table 5 is a diagram showing the change of the evaporation amount and the water level level with time. In the case of the evaporation amount, the variation in the conventional method is severe and the change cycle is fast, and the water level fluctuates severely. The change is relatively small and stable.

Claims (2)

The oxygen sensor 1 is installed in the boiler exhaust part where exhaust gas is discharged to measure the amount of oxygen contained in the exhaust part, and the measurement signal of the oxygen amount is input to the microcomputer controller 2 to calculate the amount of air required for combustion and the blower operation inverter Fuel economy adjusting means for driving the blower motor 19 by calculating a value; A ground rod (A), the lowest level sensing electrode (B), the lowest level sensing electrode (C), the upper limit level sensing electrode (D), and the maximum level sensing electrode (E), each of which is installed in communication with the reservoir of the boiler pipe. Is provided with two electrodes, the ground rod (A) of the five electrodes are connected to the microcomputer controller is installed to transmit a ground signal, the lowest level detection electrode (B) is installed to generate the lowest level detection signal is the electrode level The lower end of the electrode (B) is installed so as to extend to be located at the lowest level of the boiler tube to generate the lowest level detection signal when falling out of the lower end of (B), the maximum level detection to generate a signal by detecting the highest level The electrode (E) is installed so that the lower end of the electrode (E) is located at the maximum level so that the water level rises to generate the highest level detection signal when the bottom of the electrode (E) comes in contact with water, Located between the lowest level and maximum level sensing electrodes (B) and (E), the lower limit level sensing electrode (C) and the appropriate level in the tube are installed to generate a signal by detecting an acceptable lower level among the appropriate levels in the tube. The upper limit water level detection electrode (D) for generating a signal by detecting an acceptable upper limit line is installed to generate a level detection signal, and the lower limit water level detection electrode (C) and the upper limit water level detection electrode (D) While the allowable upper and lower water level is repeated a certain number of times, the water level fluctuation time is checked in real time to calculate the average learning value, and then the water supply inverter is driven by the water supply inverter to satisfy the steam consumption and the required water supply using the average learning value as a reference point. Of industrial boilers equipped with continuous water supply system to achieve the required amount of water supply by controlling the lift by changing the frequency. Fuel economy control and continuous water supply system. delete