JPH0769077B2 - Combustion control device for hot water boiler - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a combustion control device for a hot water boiler, which is intended to prevent a decrease in temperature of hot water supplied to a load.

[0002]

2. Description of the Related Art Conventionally, in a hot water boiler, the temperature of hot water in a can is detected and the burner is turned on based on this detected temperature.
-OFF control is performed. In the hot water boiler,
A circulation line consisting of a circulation pump and a heat exchanger is connected, and hot water is circulated in this circulation line to perform heat exchange between hot water and cold water in the heat exchanger and load the heated water. I am trying to supply it to.

[0003]

In the hot water boiler system having such a configuration, for example, the full capacity of the can is set to 30.
If the volume is liter and the circulation rate is 160 liters / minute, the water in the can is calculated to be replaced in about 11.25 seconds. Usually, the water in the can has a high temperature layer in the upper part and a low temperature layer in the lower part, and among these temperature layers, the hot water temperature in the upper part of the can is detected to perform combustion control. It is not possible to detect the decrease in hot water temperature until the water in the low temperature layer rises in the can and reaches the upper part of the can. In order for the water in the low temperature layer to rise in the can body and reach the upper part of the can body, it takes a time equivalent to the above-mentioned can water replacement time. For this reason, if the pre-purge → combustion is performed after waiting for the low-temperature water to reach, the temperature of the can water further decreases during the pre-purge time, and the temperature of the hot water supplied to the load side also decreases substantially.
Therefore, there is a problem that it is not possible to follow the load request, and the low temperature water is supplied to the load side during the response delay time.

[0004]

The present invention has been made in view of the above-mentioned problems, and a hot water boiler is provided with a first temperature sensor for detecting a hot water temperature in a can, a circulation pump and a heat exchange. Connect the circulation line consisting of inserting the vessel,
The second position is provided upstream of the heat exchanger in this circulation line.
A temperature sensor and a third temperature sensor are provided at positions downstream of the heat exchanger, and the detected temperature T ₁ of the first temperature sensor is set.
The combustion start signal and the combustion stop signal are output to the burner attached to the hot water boiler in accordance with the value of, and the value of the temperature T ₁ detected by the first temperature sensor reaches the temperature at which the combustion start signal should be output to the burner. Even if not, the temperature detected by the second temperature sensor T ₂ and the temperature detected by the third temperature sensor T ₃
A combustion control means for outputting a combustion start signal to the burner is provided when the difference with respect to time or the amount of temporal change of the ratio is larger than a preset value.

[0005]

According to the above construction, even if the temperature of the hot water in the can is not lowered to the temperature at which the combustion start signal should be output to the burner, that is, in the burner standby state between the burner OFF and the burner ON. Also detects the difference or ratio of the hot water temperatures at the upstream and downstream positions of the heat exchanger in the circulation line, and outputs a combustion start signal to the burner when the temporal change is greater than a preset value. Therefore, it is possible to quickly detect the increasing tendency of the amount of hot water used in the load and output the combustion start signal to the burner earlier.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram of a hot water boiler according to an embodiment of the present invention. (4) is a hot water storage type hot water boiler, for example, an inner cylinder and an outer cylinder (both not shown)
A can body is constructed from the above, a hot water storage space is provided between both cylinders, and the burner is burned in the inner cylinder to heat the water supplied to the can body to warm water. Hot water outlet (10) of the hot water boiler (4)
A circulation line (7) formed by inserting a circulation pump (5) and a heat exchanger (6) in series is connected between the hot water return port (11) and the hot water return port (11). (12) is a three-way valve, which is inserted in the hot water supply line (14) connected to the load side hot water outlet (13) of the heat exchanger (6),
In order to keep the temperature of the hot water supplied to the load (15) such as curran constant, the amount of hot water from the heat exchanger (6) and the cistern tank (1
The mixing ratio of the amount of cold water from 6) is automatically controlled.

The first temperature sensor (1) is a hot water boiler (4)
The hot water temperature inside the can is detected. (2) is a second temperature sensor, which is provided upstream of the heat exchanger (6) in the circulation line (7), and (3) is a third temperature sensor, which performs heat exchange in the circulation line (7). It is provided at the downstream position of the vessel.
(9) is a combustion control means, which outputs a combustion start signal and a combustion stop signal to a burner (8) attached to the hot water boiler (4) according to the value of the temperature T ₁ detected by the first temperature sensor (1). while, when said greater than a value temporal change amount of the difference or ratio is preset between the detected temperature T ₃ of the detected temperature T ₂ and the third temperature sensor (3) of the second temperature sensor (2), wherein Burner
It has the function of outputting a combustion start signal to (8).

Next, an example of the control circuit will be described with reference to FIG. Reference numeral (17) is an operation switch including an operation switch, and (18) is a memory for storing temperature data detected by the second temperature sensor (2) and the third temperature sensor (3). The combustion control means (9) is composed of a microcomputer, and the control procedure is stored in advance in its internal memory or external memory, and each device is controlled in accordance with the control procedure. For example, a circulation pump
(5) is operated continuously while the operation switch (17) is turned on, and the burner (8) is controlled according to the control procedure as shown in FIG.

The burner control of the present invention will be described below with reference to FIG. In step S1, the temperature T ₁ detected by the first temperature sensor (1) is determined. If T ₁ is below the temperature T _{ON at} which the combustion start signal should be output to the burner (8), or if the burner (8)
Temperature above which the combustion stop signal should be output to T _OFF or T _ON
<T ₁ <T _OFF is determined. If so, the process proceeds to step S2, the pre-purge operation is performed, and then the burner
Start the combustion of (8). If it is determined in step S1, the process proceeds to step S4, the post-purge operation is performed, and then the combustion of the burner (8) is stopped.

[0010] If it is determined in step S1, the process proceeds to step S3, whether the current state is caused by the transition to T _OFF from T _ON, whether the T _OFF was caused by migration to T _ON determines . If YES is determined in the step S3, the process proceeds to a step S5 and it is determined whether or not the following expression is satisfied. (T ₂₂ −T ₃₂ ) − (T ₂₁ −T ₃₁ )> T ₀ where T ₂₁ and T ₂₂ represent the hot water temperature at the upstream position of the heat exchanger (6) in the circulation line (7), and ₂₁ is t of T ₂₂
The data before seconds, T ₃₁ and T ₃₂ are circulation lines (7)
Shows the hot water temperature at the downstream position of the heat exchanger (6) at
₃₁ is the data t seconds before T ₃₂ . For T ₂ and T ₃ , sampling is performed at a preset cycle (for example, 500 msec), sampling data for t seconds is stored in the memory (18),
I try to erase it after t seconds. This memory can be configured as a first-in, first-out FIFO memory, but may be another semiconductor memory,
It may be the internal memory of the microcomputer. t
Is set to, for example, 2 seconds, and T ₀ is set to, for example, 3 ° C.

When the amount of hot water used in the load is 0 or small, the above equation is not satisfied, and the process proceeds to step S4, in which the burner continues the combustion stopped state. When the amount of hot water used under load increases, for example, T ₂₁ which is the data 2 seconds ago becomes 80.
C., T ₃₁ was 75 ° C., and (T ₂₁ −T ₃₁ ) was 5 ° C., but the current data T ₂₂ is 80 ° C. and T ₃₂ is 70 ° C.
When (T ₂₂ −T ₃₂ ) becomes 10 ° C. at the temperature of the condition, the above equation is satisfied, and the process proceeds to step S2. Therefore, even if the detected temperature T _{1 of} the first temperature sensor (1) is equal to or higher than T _OFF , the burner combustion can be started after the pre-purge operation is performed. Therefore, the combustion of the burner can be started earlier before the low temperature water reaches the upper first temperature sensor mounting position in the can body, and the low temperature water is prevented from being supplied from the heat exchanger to the load. can do.

If NO is determined in step S3, the process proceeds to step S2 and the burner combustion is continued.

The present invention is not limited to the above-mentioned embodiment, and the hot water boiler has a can structure other than the hot water storage type.
It may be a flow-through type can body in which a large number of vertical water pipes are connected in communication between the upper header and the lower header. Also, the above equation (T
₂₂ −T ₃₂ ) − (T ₂₁ −T ₃₁ )> T ₀ is for determining the temporal change amount of the difference between the inlet side temperature and the outlet side temperature of the heat exchanger, but other than this. It may be a judgment formula,
For example, the temporal change amount of the ratio between the inlet side temperature and the outlet side temperature of the heat exchanger may be determined.

[0014]

EFFECTS OF THE INVENTION Since the present invention has the above-described structure, heat is generated before the temperature of the hot water in the can falls to the temperature at which the combustion of the burner should be started, that is, even in the burner standby state. From the time variation of the difference or ratio between the inlet hot water temperature and the outlet hot water temperature of the exchanger, the increase tendency of the hot water usage under load is quickly caught and the combustion of the burner is started much earlier than before. be able to. Therefore, it is possible to quickly respond to the request of the load, there is no response delay, and the problem that the temperature of the hot water supplied to the load side significantly decreases during the response delay time is also solved.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of a control circuit in one embodiment of the present invention.

FIG. 3 is a flowchart showing a main control operation according to the embodiment of the present invention.

[Explanation of symbols]

 1 1st temperature sensor 2 2nd temperature sensor 3 3rd temperature sensor 4 Hot water boiler 5 Circulation pump 6 Heat exchanger 7 Circulation line 8 Burner 9 Combustion control means

Claims (1)

[Claims] A circulation line comprising a hot water boiler (4) provided with a first temperature sensor (1) for detecting the temperature of hot water in a can, and a circulation pump (5) and a heat exchanger (6) inserted therein. (7)
And a second temperature sensor (2) is provided upstream of the heat exchanger (6) in the circulation line, and a third temperature sensor (3) is provided downstream of the heat exchanger (6). In addition to outputting a combustion start signal and a combustion stop signal to a burner (8) attached to the hot water boiler (4) according to the value of the detected temperature T ₁ of the first temperature sensor (1), the first temperature sensor ( 1)
Even if the value of the detected temperature T ₁ of the second temperature sensor has not reached the temperature at which the combustion start signal should be output to the burner (8).
(2) detecting when the temporal variation of the difference or ratio between the detected temperature T ₃ of the temperature T ₂ and the third temperature sensor (3) is greater than the preset value, combustion start signal the to the burner (8) A combustion control device for a hot water boiler, characterized in that a combustion control means (9) for outputting is output.