JPH0134055Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a boiler dry firing prevention device. To be more specific, this invention detects abnormalities by capturing the combustion equipment operating time when the water supply pump is stopped and comparing this with the set time. This relates to prevention of boiler dry firing.

Overheating of the can due to an abnormal drop in the boiler water level can lead to serious accidents such as splitting and bursting of the can. Conventionally, as a method for detecting this abnormal drop in water level, an electrode method that takes advantage of the property of boiler water to easily conduct electricity has been generally used. That is, a water level gauge box is installed outside the boiler, and its upper part is connected to the steam section of the boiler through an upper connecting pipe, and its lower part is connected to the water section of the boiler through a lower connecting pipe, so that the water level inside the water level gauge box can be monitored. The method used was to detect the water level using a water surface detection rod installed inside the water level meter box. However, with this method, the water level control device may malfunction due to blockage of the upper and lower connecting pipes, scale adhesion to the electrode holder of the water level detection rod, and in the worst case, an abnormally low water level. However, the combustion continued, and there were even cases of dry burning.

In view of the above points, the present invention aims to provide a boiler dry firing prevention device with a simple structure that avoids the effects of scale, sludge, etc. that are unavoidable for boilers. Compare the operation time t ₀ of the water supply pump with the set time T ₀ corresponding to the standard operation time of the water supply pump under normal conditions,
Discriminator circuit A that outputs a first electrical signal (special water supply signal) if t ₀ is greater than T ₀ and outputs a second electrical signal (normal water supply signal) if t ₀ is smaller than T ₀ is connected to the feed water pump by a signal line, receives the operation signal from the combustion device installed in the boiler and the stop signal from the water feed pump, integrates the combustion device operating time _t1 while the water feed pump is stopped, and calculates the output from the discriminator A. If the signal is the first electric signal (special water supply signal), compare the set time T _{11 corresponding to the standard combustion time while the water supply pump is stopped immediately after performing a special water supply such as full blowing of canned water with the above t 1 .}
If t ₁ is greater than T ₁₁ , the third electric signal (abnormal signal) is output, and if the signal from discriminator A is the second electric signal (normal water supply signal), the can water amount within the boiler water level control width is output. The _set time T ₁₂ corresponding to _the standard combustion time when _the feed water pump is stopped, which is calculated from This boiler dry firing prevention device is characterized in that a discrimination circuit B that outputs a signal) is connected to the water pump/discrimination circuit A and the combustion device through a signal line.

The present invention will be described below with reference to the drawings. The figure is an explanatory diagram of an embodiment of the present invention. In the figure, a water supply pump 2 is installed in the water supply section of a boiler 1, and the water supply pump 2 is turned on and off by a water supply control device (not shown) provided in the boiler 1.
During normal operation, the water level of the boiler 1 is maintained at a constant range, and when the boiler is started, water is supplied to the boiler 1 to a level higher than the water level during normal operation to prevent overheating of the steam section. A combustion device 4 is provided in the combustion section of the boiler 1, and this combustion device 4 performs ON-OFF combustion by a boiler pressure control device (not shown) provided in the boiler 1 to maintain the boiler pressure within a constant range. . The discrimination circuit A3 is connected to the water supply pump 2 through a signal line, and receives the operation signal from the water supply pump 2 to determine the operation time of the water supply pump in the -cycle.
t ₀ is integrated, and this water supply pump operation time t ₀ is compared with the set time T 0 corresponding to the water supply pump standard operation time during normal operation, which is set in the discrimination circuit A, and t _{0 is}
If t ₀ is greater than T 0 , a first electrical signal (special water supply signal) is output, and if t ₀ is smaller than T ₀ , a second electrical signal (normal water supply signal) is output. The discrimination circuit B5 includes the water pump 2, the discrimination circuit A3, and the combustion device 4.
is connected by a signal line, receives the operation signal of the combustion device and the stop signal of the water supply pump, integrates the combustion device operation time t ₀ while the water supply pump is stopped, and the signal from the discrimination circuit A3 is connected to the first If it is an electric signal (special water supply signal), the combustion device operating time _t1 is determined by the discrimination circuit B5.
Compare with the set time T ₁₁ corresponding to the standard operating time while the water supply pump is stopped immediately after performing special water supply such as full blow-off of can water or high-position water supply to prevent overheating of the can at boiler startup. , if t ₁ is greater than T ₁₁ , a third electrical signal (abnormal signal) is output, and if the signal from the discrimination circuit A3 is a second electrical signal (normal water supply signal), the combustion device operating time is
Compare t ₁ with the set time T ₁₂ corresponding to the standard combustion time during normal operation calculated when the feed water pump is stopped from the boiler water level control width set in the discrimination circuit B5 and the evaporation amount of the boiler capacity. , t ₁ is T ₁₂
If it is larger, a third electrical signal (abnormal signal) is output. Note that the combustion device operation time _t1 while the water supply pump is stopped is reset to the original state when the water supply pump is activated, and if the combustion device shifts to combustion while the water supply pump is stopped, the integration of the operation time is started again.

Next, the effect will be explained. At startup, a water level control device (not shown) supplies water to a level higher than the water level during normal operation to prevent overheating of the steam section, and after steaming, the water level is controlled to the level during normal operation. On the other hand, the combustion device is a boiler pressure control device (not shown)
The boiler pressure is maintained within a certain range by performing ON-OFF combustion. Note that if the boiler continues to operate for a long time and the can water becomes concentrated, the boiler operation is stopped, and after all the can water is blown out, water is supplied to the specified water level by the water level control device, and combustion begins. During the operation of the boiler, the discrimination circuit A integrates the operating time _t0 of the -cycle of the feed water pump, and compares this operating time _t0 with a set time _T0 corresponding to the standard operating time of the water pump during normal operation. When the boiler water level is set higher than during normal operation when the boiler is started, or when water is supplied immediately after all of the canned water has been blown, the operating time of the water pump will be longer than the standard operating time of the water pump during normal operation. That is, t ₀ becomes larger than T ₀ and the discrimination circuit A outputs the first electric signal (special water supply signal). The discrimination circuit B that receives the first electric signal (special water supply signal) receives the activation signal from the combustion device and the stop signal from the water supply pump, integrates the combustion device operating time t ₀ while the water supply pump is stopped, and calculates the special The set time T ₁₁ corresponding to the standard combustion time while the water supply pump is stopped immediately after the water supply is performed is compared with the above-mentioned t ₁ .
If the water supply control system is normal and the water supply pump is operating normally on and off by the water supply control device, t ₁ is T ₁₁
Although it will be smaller, if an abnormality occurs in the water supply control system, combustion will continue with the water supply pump stopped and _t1 will be greater than _T11 , causing discriminator B to output the third electric signal (abnormal signal).
Output. If the boiler is started normally, steaming is completed, and normal operation begins, T ₀ is set to the standard combustion time, so t ₀ becomes equal to or less than T ₀ , and discriminator circuit A and second Outputs an electrical signal (normal water supply signal). Upon receiving this second electrical signal (normal water supply signal), the discrimination circuit B integrates the combustion device operating time _t1 while the water supply pump is stopped, based on the signals from the combustion device and the water supply pump, and calculates the amount of canned water within the boiler water level control width. Set time T ₁₂ corresponding to the standard combustion time when the feed water pump is stopped, calculated from the evaporation amount of the boiler capacity
is compared with _t1 above. If the water supply system is normal and the water supply pump is operated ON-OFF by the water supply control device, t ₁ will be smaller than T ₁₂ , but if an abnormality occurs in the water supply control system, the water supply pump will be stopped as in the case of special water supply. As combustion continues, t ₁ becomes larger than T ₁₂ and discriminator B
Also at this time, the third electric signal (abnormal signal) is output. Although not shown in this embodiment, this abnormality signal can be used to display an abnormality on an alarm display device, or to stop combustion to directly prevent the boiler from running dry.

As detailed above, this invention is a method of detecting abnormalities in the operating time of the combustion equipment using the operating signals of the combustion equipment and the feed water pump, and preventing dry firing. - It is possible to create a dry firing prevention device with a very simple structure that is not affected by sludge, etc.

[Brief explanation of the drawing]

The figure is an explanatory diagram of an embodiment of the present invention. 1...Boiler, 2...Water pump, 3...Discrimination circuit A, 4...Combustion device, 5...Discrimination circuit B.

Claims (1)

[Scope of utility model registration request] Compare the operating time t ₀ of the feed water pump 2 installed in the boiler 1 with the set time T ₀ corresponding to the standard operating time of the water pump in normal times, and if t ₀ is greater than T ₀ , the first
A signal line connects the water supply pump 2 to the discrimination circuit A3 which outputs an electric signal (special water supply signal) and outputs a second electric signal (normal water supply signal) if t ₀ is smaller than T ₀
The signal from the discriminator A3 is connected to the boiler 1, receives the operating signal from the combustion device 4 provided in the boiler 1, and the stop signal from the water feed pump 2, integrates the combustion device operating time _t1 while the water feed pump is stopped, and outputs the first signal from the discriminator A3. If this is an electric signal (special water supply signal), compare the set time T ₁₁ corresponding to the standard combustion time while the water supply pump is stopped immediately after performing a special water supply such as full blowing of canned water with the above t ₁ to find out that t ₁ is T If it is greater than ₁₁ , a third electrical signal (abnormal signal) is output,
If the signal from discriminator A is the second electric signal (normal water supply signal), the setting corresponds to the standard combustion time when the water supply pump is stopped, which is calculated from the amount of water in the boiler water level control width and the evaporation amount in the boiler capacity. Said time T ₁₂
A discrimination circuit B5, which outputs a third electric signal (abnormal signal) when compared with _t1 and if _t1 is greater than _T12 , is connected to the water pump 2, discrimination circuit A3, and combustion device 4 through a signal line. A boiler dry firing prevention device characterized by: