JPH0136053Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a bleed air control device in a vacuum hot water generator.

Conventionally, in a hot water generator that generates steam by heating a heat medium liquid, such as water, sealed in a closed container and heats an object with the steam, by reducing the pressure inside the closed container, There is a vacuum-type hot water generator that improves the efficiency of steam generation, but since this equipment is operated at a pressure within the closed container below atmospheric pressure, there is a risk of air entering the container. If atmospheric inert gas accumulates inside the container, the heat exchange efficiency will drop significantly, so a method is used to periodically bleed air from the sealed container using a timer to maintain a constant pressure. However, since air is always extracted periodically regardless of pressure changes inside the container, steam is also extracted periodically at the same time as air extraction, causing a decrease in water, heat loss when replenishing water, and loss of make-up water. Separation of dissolved air has the disadvantage of reducing heat exchange efficiency, and for this reason, the Japanese Patent Publication No. 52-47083 was developed as a device that can bleed air within the necessary limits depending on the pressure inside the closed container. There is a technology disclosed in the publication, which involves providing a gas reservoir separately in communication with the outside of the sealed container, detecting the temperature inside the gas reservoir, and extracting air from the gas reservoir as the temperature changes and sealing the container. It is designed to keep the pressure inside the container constant by extracting air only when the pressure in the container is below a set value determined by temperature measurement.A separate gas reservoir chamber must be constructed, and the temperature inside the gas reservoir chamber must be kept constant. In order to detect this, it is necessary to measure the temperature inside the gas reservoir, and the difference between the temperature inside the gas reservoir and the temperature inside the closed container is used as the standard, regardless of the actual temperature of the hot water that was heat exchanged. There is a risk that the measured temperature may vary depending on the location within the gas reservoir or the sealed container, or that the temperature may be inaccurate due to the temperature being lowered only near the point where the air enters. Since it does not measure the temperature inside the container, it was not possible to accurately detect the pressure inside the container, that is, the partial pressure of the inert gas.

This idea compares the difference between the steam temperature inside the closed container and the heated water temperature that has been heat exchanged, and automatically bleeds air when the difference exceeds a certain level.
A microcomputer samples the steam temperature in the container and the hot water temperature after heat exchange at predetermined time intervals, and bleeds air in the sealed container for a preset and memorized bleed operation time based on the temperature difference between the two. By controlling the bleed device to perform the necessary and sufficient bleed air, the bleed air control device in the bleed type heat exchange device can be used to minimize the temperature drop, decrease in heat transfer water, and heat loss caused by the bleed air. This is what we intend to provide.

An embodiment of this invention will be described in detail based on the drawings. A indicates a vacuum hot water generator, and the device A includes a closed container 2 filled with canned water 1 as a heating medium, a heated It is composed of a burner 3 as a device, a water pipe 4 for heat exchange between the steam in the container 2 and the water to be heated, an air extraction device 5, and a microcomputer 6 for controlling the entire device A. .

The airtight container 2 has a steam temperature sensor 7 attached to the inner wall of the container 2, and the output of the sensor 7 is as follows.
Input a is input to a microcomputer 6, and a water level detector 8 for canned water 1 is also provided, and when the water level falls below the lower limit, a water supply valve 9 is activated.
It is configured to open and supply water up to the same water level upper limit.

The burner 3 is for heating and evaporating the canned water 1, and a microcomputer 6 controls the blinking and the amount of heat generated b.

The water pipe 4 communicates with an external pipe line 10, and a circulation pump 11 transfers the heat of the steam inside the closed container 2 to the heated water passing through the water pipe 4, and at the same time, the steam condenses into the canister. The water becomes water 1 and is heated and evaporated again by the heat of the burner 3. A hot water temperature sensor 12 is attached to the outlet of the water pipe 4, and the output of the sensor 12 is input to the microcomputer 6. It is becoming more and more like this.

The air bleed device 5 extracts the gas phase in the closed container 2 using the air bleed pump 13. A check valve 14 that flows only in the direction of the pump 13 and a microcomputer 6
A solenoid valve 15 that opens and closes according to the output e from the solenoid valve 15 is interposed in series.

The microcomputer 6 has a built-in clock timer, and samples the output a from the steam temperature sensor 7 and the output c from the hot water temperature sensor 12 at predetermined time intervals to calculate the temperature difference ΔT between the two. Then, the optimum bleed time is set in advance based on the same temperature difference △T, and the same time is read out from the storage device 6-1 so that it can be accessed at the same temperature difference △T. can be,
As an example, in this embodiment, when the temperature difference △T is 10°C or less, air bleed is not performed, and when the same temperature difference △T is 10°C, air bleed is not performed.
If the same temperature difference △T exceeds 10℃ for 1 minute, increase 1 minute for every 5℃, and when the same temperature difference △T is 55℃
A bleed time of 10 minutes is set and arrayed and stored in the storage device 6-1, and the corresponding bleed time is read out based on the same temperature difference ΔT.

If the temperature difference △T is 10°C or more, the microcomputer 6 starts the extraction pump 13 via the output relay group 16 for a predetermined period of time (5 in this example).
When the inside of the air extraction device 5 has been sufficiently reduced in pressure after 3 seconds), the electromagnetic valve 15 is opened for the above-mentioned air extraction time to bleed out the inert gas inside the closed container 2.

In addition, 6-2 in the figure is an AD converter.

Furthermore, an air bleed command can be manually input into the microcomputer 6 at any time to operate the air bleed device for any desired period of time.

In addition, the microcomputer 6 includes the burner 3 ignition procedure, burner extinguishing procedure, initial air extraction procedure for the first operation of the hot water generator A, steam temperature control procedure, etc.
Routines necessary for the operation of the heat exchanger A are set in advance and input into the storage device 6-1.

In addition, as another embodiment, a pressure sensor 23, a cold water temperature sensor 24 at the water pipe inlet, a flow rate sensor 25 in the middle of the external water pipe, etc. are added to the closed container 22, and the output is inputted to the microcomputer 26, and the temperature of the water pipe 27 is increased. The amount of heat exchanged is calculated, the amount of heat is referred to the pressure inside the container and the steam temperature, the partial pressure of the inert gas is calculated, the partial pressure of the gas is set in advance as a reference, and the partial pressure is input into the storage device 26-1. It is also possible to configure the air bleed device 28 to operate only for the set air bleed operation time.

The embodiment of this invention is constructed as described above, and when a command to start the hot water generator A is input to the microcomputer 6, the computer 6 follows the burner 3 ignition procedure and performs pre-purge and pre-ignition of the burner 3. After steps such as fuel injection, the burner 3 is ignited, and the canned water 1 in the sealed container 2 is heated and evaporated to a predetermined temperature (88°C in this example).
When this is reached, the first bleed operation is performed.

Since canned water 1 releases the largest amount of inert gas during initial evaporation, the initial extraction operation is performed regardless of the time interval. 7, the computer 6 immediately starts the bleed pump 13, and after a predetermined period of time (5 seconds in this example) has passed and the pressure in the bleed device 5 has been sufficiently reduced, it starts the solenoid valve 15. By opening the valve 15 and keeping it open for a set time, the valve 15 is closed to bleed out the gas containing the inert gas in the closed container 2.

After the first air extraction operation, the hot water generator A enters steady operation, and if the water level of canned water 1 decreases, the water supply valve 9
is opened to maintain the same water level, and the burner 3 is controlled by the computer 6 via the sensor 7 to maintain a substantially constant temperature.

When a predetermined period of time (in this example, 2 hours) has elapsed after entering steady operation, the computer 6 samples the above-mentioned temperature and hot water temperature using the same sensors 7 and 12 (in this example, averages over 3 minutes), and calculates the temperature between the two. The temperature difference is calculated, the bleed time stored in advance in the storage device 6-1 is read out, and the bleed device 5 is operated according to the above bleed procedure. This operation is performed only for the time read out by ΔT, and thereafter, the above-mentioned air extraction operation is performed at predetermined time intervals.

The extraction time is set based on the temperature difference between the steam temperature and the hot water temperature, and in this example,
If the temperature difference between the first two is 10°C or less, do not bleed air and
℃ for 1 minute, every 5℃ above 10℃
The bleed time is increased to 10 minutes at 55°C. Note that heating by the burner 3 is not performed while the bleed device is in operation.

According to this invention, the extraction device of the vacuum hot water generator is controlled by a microcomputer that calculates the partial pressure of the inert gas from various sensor inputs attached to the heat exchanger. By performing extraction operation for an optimally set time depending on the pressure, heat loss such as steam loss and steam temperature drop due to extraction can be minimized. It is possible to minimize the inert gas contamination with the water supply and break the vicious cycle of air extraction, steam loss, canned water reduction, water supply, inert gas increase, and air extraction again, making it possible to improve vacuum hot water generators. It has the effect of always maintaining a highly efficient state.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a vacuum hot water generator having a bleed air control device according to the gist of the present invention. FIG. 2 is a schematic diagram of another embodiment. A...Vacuum hot water generator, △T...Temperature difference, 2
... airtight container, 5 ... air extraction device, 6 ... microcomputer, 6-1 ... storage device.

Claims (1)

[Scope of utility model registration request] The output of the steam temperature sensor 7 in the closed container 2 of the vacuum hot water generator A and the output of the hot water temperature sensor 12 after receiving heat are input to the microcomputer 6, and the computer 6 calculates the temperature difference ΔT between the former two. Then, the air bleed time set based on the same temperature difference ΔT stored in the storage device 6-1 in advance is read out, and the air bleed device 5 is operated for the read air bleed time based on the output from the computer 6. A bleed air control device for a vacuum hot water generator configured to