JP3166189B2 - Control method of decompression boiler type vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum boiler type evaporator
It relates to a control method .

[0002]

2. Description of the Related Art Recently, use of LNG (liquefied natural gas) as a low-pollution energy source is rapidly expanding. LNG is a natural gas mainly composed of methane (CH4) cooled to cryogenic temperature and liquefied. It is temporarily stored in an LNG storage facility, etc., introduced into a vaporizer, and supplied for various uses. It is supposed to. As the LNG vaporizer, there are a device using seawater, river water, or the like as a heating source of LNG, and a device using combustion heat of LNG or the like. Further, a vaporizer using an intermediate heat medium has been devised. As an example of this method, a decompression boiler type vaporizer can be mentioned. This decompression boiler type vaporizer 1
Applies low-temperature steam in a decompressed state as an intermediate heat medium. As shown in FIG.
A reduced-pressure steam can 3 communicating with the reduced-pressure steam generator 2. The reduced-pressure steam generator 2 is provided with a heating medium pipe 4 through which heated steam is circulated, and water is retained therein. The vacuum steam can 3 is provided with a heat transfer tube 5 that circulates LNG. The air in the reduced-pressure steam generator 2 and the reduced-pressure steam can 3 communicating therewith is sucked by a vacuum pump (not shown) to reduce the pressure, and the water in the reduced-pressure steam generator 2 is supplied with a heating medium through which heated steam is passed. The low-temperature steam is generated by the tube 4, and the low-temperature steam vaporizes LNG flowing through the heat transfer tube 5. In such a reduced-pressure boiler-type vaporizer 1, the temperature of water in the reduced-pressure steam generating can 2 is detected by a water temperature sensor, and a flow rate control valve is controlled by a controller so that the temperature becomes a set temperature. Temperature control for adjusting the amount of steam flowing into the fuel cell 4 is performed.

[0003]

However, the temperature of water
In the conventional method of controlling by directly detecting the degree,
The heat capacity of the water inside the steam generator can
The water temperature sensor used for detection itself has a detection delay
The dead time and the time constant are both large due to
Control after disturbance due to change in flow rate of hot fluid
There is a problem that it takes time to stabilize. one
On the other hand, the temperature and pressure of water in the reduced-pressure steam generator can be one-to-one.
As described above, the water temperature is detected and
Instead of controlling the pressure, the pressure inside the reduced pressure steam
Although it can be controlled, the water temperature and pressure
The one-to-one correspondence is that the inside of the vacuum steam generator is saturated.
Only when non-condensable gas such as air
Therefore, if the non-condensable gas stays, the correspondence between the temperature and the pressure of the water in the reduced-pressure steam generator is shifted , and the vaporized LNG
Temperature may be lowered. The present invention has been made in view of such problems, there is a stable, enabling good good control responsive and the control of the vacuum boiler type evaporator
The aim is to provide a method .

[0004]

In order to solve the above-mentioned problems, a control method for a reduced-pressure boiler-type vaporizer according to the present invention includes a reduced-pressure steam generating can provided with a heating medium tube and retaining water.
A reduced-pressure steam can provided with a heat transfer tube communicating with the reduced-pressure steam generator and flowing a low-temperature fluid, wherein a water temperature detecting means in the reduced-pressure steam generating can and a pressure detecting means in the reduced-pressure steam generating can are provided. In addition, the heat transfer tube is provided with an outgassing temperature detecting means for detecting the temperature of the vaporized low-temperature fluid, and the controller of the flow control valve provided in the heat transfer tube is provided with a detection signal cutoff.
The temperature detecting means and the pressure detecting means via the switching means.
Feedback control is performed selectively as
And the pressure detection means and the outgassing temperature detection.
The correspondence between the detection signals of
Compare with the correspondence in the ideal state where there is no stagnation
To detect non-condensable gas stagnation by detecting the deviation.
Control means for outputting the detection signal,
Switch to the force detection means side, and the pressure in the
The flow control valve is flown by the controller so as to reach the set pressure.
Feedback control to control the amount of heat medium flowing through the heat medium tube.
Control means, and the pressure detecting means and the outgassing temperature detecting means.
The corresponding relationship between the detection signals of
If the control means detects that the response has deviated,
Switch the detection signal switching means to the temperature detection
A controller so that the temperature of the water in the steam generator can reach the set temperature.
Feedback control of the flow rate control valve by
The supply amount of the heat medium flowing through is controlled . In addition, the control method of the decompression boiler type vaporizer of the present invention
If the flow rate of the low-temperature fluid is changed in the
Switch the signal switching means to the temperature detecting
The temperature of the water in the generator can
The flow control valve is fed back by the controller until the
Control the supply amount of the heat medium flowing through the heat medium tube
In both cases, when the set temperature is reached, the detection signal
Switch to the force detection means side, and the pressure in the
The flow control valve is flown by the controller so as to reach the set pressure.
Feedback control to control the amount of heat medium flowing through the heat medium tube.
It is characterized by controlling.

[0005]

[Action] In the reduced pressure steam generator and in the reduced pressure steam can
The temperature, i.e., the can water temperature and the pressure inside the can, have a one-to-one correspondence.
This correspondence can be represented by a saturated vapor pressure curve.
Wear. For this reason, instead of controlling by temperature, by pressure
Controlling the supply amount of heat medium flowing through the heat medium tube by control
Can be. However, this one-to-one correspondence is as described above.
In a saturated state, non-condensable gas such as air
This is only true in the ideal case where the stagnation does not stay.
On the other hand, still water temperature (Θs), low-temperature fluid flow rate (G), outlet gas temperature
(Θ) and the low-temperature fluid inlet temperature (Θi), the following relationship holds: Θ = (1−f (G)) Θs + f (G) Θi (where f (G) is a parameter of the heat transfer area).
Data is a monotonically increasing function). That is, the low-temperature fluid flow rate
(G) and the state where the inlet temperature of low-temperature fluid (Θi) does not change
, The gas temperature leaving the boiler water temperature (Θs) (Θ) is one-to-one
There is a correspondence. Therefore, in the ideal state described above,
Means that the water temperature (Θs) and the pressure inside the can have a one-to-one correspondence.
Therefore, the pressure in the can and the outgassing temperature (Θ)
There is a correspondence. However, non-condensing property such as air in the can
If gas is stagnated, the water temperature in the ideal condition
Deviate from the one-to-one correspondence between (Θs) and the pressure in the can
From the same, one-to-one pairing of the can pressure and the outgassing temperature (Θ)
Responsiveness is also lost. Conversely speaking, can pressure and outgassing temperature
(Θ) corresponds to the ideal state
If it is detected that non-condensable gas has
Can be detected. Therefore, in the present invention,
Normally, control by the pressure inside the can is used instead of control by the water temperature.
Control can eliminate the former disadvantage of control.
In both cases, the change in the correspondence between can pressure and outgassing temperature (Θ)
Detected that non-condensable gas has accumulated in the can.
Control from can pressure to can water temperature
By switching, appropriate control can be performed. Also low temperature
When changing the flow rate of the fluid,
Control by the water temperature until the temperature reaches the set temperature
Thus, appropriate control can be performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a control method of a decompression boiler type vaporizer according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 10 denotes a reduced-pressure boiler-type vaporizer. The reduced-pressure boiler-type vaporizer 10 has a configuration in which a reduced-pressure steam generator 11 and a reduced-pressure steam can 12 are communicated with each other. ), The pressure in the exhaust gas is reduced, and the water stored in the depressurized can is heated to generate low-temperature steam, and this steam is used as a heating source for LNG vaporization. The reduced-pressure steam generating can 11 is
Heat medium pipe 14 for flowing hot steam through flow control valve 13
Are arranged and configured to pass through the stored water.
ing. On the other hand , LNG flows into the reduced pressure steam can 12 at a flow rate of
A heat transfer tube 16 circulated through the control valve 15 is disposed and configured.
Have been. The reduced-pressure steam generating can 11 has a reduced-pressure steam.
Detecting the temperature of water in the gas generating can 11, that is, the can water
Temperature sensor 17 for measuring the pressure inside the reduced pressure steam generating can 11
A pressure sensor 18 for detecting the force, that is, the pressure in the can, is provided.
Have been killed. Further, the heat transfer tube 16 was vaporized.
An output gas temperature sensor 19 for detecting the temperature of LNG is provided.
Have been. On the upstream side of the heat medium tube 14 and the heat transfer tube 16
Are provided with flow control valves 13 and 15, respectively.
The flow control valves 13 and 15 are controlled by controllers 21 and 22, respectively.
The amount is controlled. To do so, the heating medium tube
14 and the heat transfer tube 16 have differential pressure type flow rate detecting means 25, 26
Is provided. Controller 2 of flow control valve 13 of heat medium pipe 14
Reference numeral 1 denotes a water temperature sensor 17 and
And electrically connected to any one of pressure sensor 18
Configuration. On the other hand, the flow rate of the heat transfer tube 16 is controlled.
The controller 22 of the node valve 15 corresponds to the flow rate of the inflowing LNG.
To determine the flow rate of the heated steam supplied through the heat medium pipe 14.
To calculate the feedforward signal for
Is electrically connected to the forward amount setting unit 24,
This feed forward amount setting unit 24
Electrically connected to the controller 21 of the flow control valve 13
ing. Reference numeral 20 denotes control means.
Is a pressure cell as a pressure detecting means in the reduced-pressure steam generator 11.
Sensor 18 and an output gas for detecting the temperature of the vaporized low-temperature fluid.
Each of the output gas temperature sensors 19 as the temperature detection means
Check the correspondence of the detection signals to make sure that non-condensable gas
Compare the corresponding relationship in the ideal state and detect the deviation.
It is configured to detect stagnation of non-condensable gas by issuing
The switching signal of the detection signal switching means 23 is generated.
It has been done. For this purpose, the control means 20
Input signal lines from the sensor 18 and the outlet gas temperature sensor 19,
An output signal line to the detection signal switching means 23 is configured.

Next, the configuration of the control means 23 will be described. Ma
In addition, as described above,
Temperature that put the steam cans 12, i.e. the boiler water temperature and Kan'nai pressure
There is a one-to-one correspondence, which corresponds to a saturated vapor pressure curve.
It can be represented by a line. Therefore, control by temperature
Instead of pressure, the heat medium flowing through the heat medium tube is controlled by pressure.
The supply amount can be controlled. However, this one-to-one pair
As described above, the response is
In an ideal state where no noncondensable gas such as air
Only in cases. On the other hand, can water temperature (Θs), low-temperature fluid
Flow rate (G), outgassing temperature (Θ) and low temperature fluid inlet temperature
(Θi), the following relationship holds: Θ = (1−f (G)) Θs + f (G) Θi (where f (G) is a parameter of the heat transfer area
Data is a monotonically increasing function). That is, the low-temperature fluid flow rate
(G) and the state where the inlet temperature of low-temperature fluid (Θi) does not change
Then, the water temperature (Θs) and the outgassing temperature (Θ) are one-to-one.
There is a correspondence. In addition, low temperature fluid flow (G) or low temperature
When the fluid inlet temperature (Θi) changes, each value
Has a one-to-one correspondence different from the above.
Therefore, in the ideal condition described above, the water temperature (Θ
s) and the pressure inside the can have a one-to-one correspondence,
The internal pressure and the outgassing temperature (も) also have a one-to-one correspondence.
However, if non-condensable gas such as air stays in the can
In the case, the water temperature in the ideal condition (Θs) and the internal pressure of the can
Similarly, because it is out of the one-to-one correspondence of forces,
The one-to-one correspondence between the pressure and the outgassing temperature (Θ) is also lost.
Conversely, the correspondence between the pressure inside the can and the outgassing temperature (Θ)
Is out of correspondence in the ideal state
Detects that non-condensable gas has accumulated in the can
be able to.

[0008] From the above, the control means 20 includes:
In the ideal state, the pressure in the can and the outgassing temperature (Θ)
Means for storing the response, pressure sensor 18 and outgassing.
Compare these values according to the input signal from the temperature sensor 19
Therefore, these values correspond to the correspondence in the ideal state.
It has a comparison judgment means to judge whether
ing. As mentioned above, the cryogenic fluid flow (G) or low
If the hot fluid inlet temperature (Θi) changes,
Value is a one-to-one correspondence different from the above
Therefore, the correspondence between the pressure in the can and the outgassing temperature (Θ) is as follows:
The low-temperature fluid flow rate (G) and low-temperature fluid inlet temperature (Θi)
You only need to store them as parameters.
The method of comparison and judgment is a method using a data table
Alternatively, a method using a functional expression can be applied.

In the above configuration, the present invention
Normally sets the detection signal switching means 23 to the pressure sensor 18 side.
The pressure in the reduced pressure steam generation can 11 is switched to the set pressure.
The flow control valve 13 is fed by the controller 21 so that
Back control to control the supply amount of heat medium flowing through the heat medium tube 14
At the same time, the control means 20 outputs the pressure sensor 18
From the input signal from the gas temperature sensor 19,
Is the cryogenic fluid flow (G) and the low
In an ideal state corresponding to the temperature of the fluid inlet (） i)
Matches the correspondence between the pressure inside the can and the outgassing temperature (Θ)
It is determined at any time whether or not this is the case. And the result of the comparison is
If it is determined that the current operating state of the pressure
maintain. On the other hand, as a result of the comparison,
If it is determined that there is a deviation, non-condensable gas
The exhaust inside the can by the exhaust means
And switching the detection signal switching means 23 to the water temperature sensor 17.
Side, and the temperature of the water in the reduced-pressure steam generation can 11 is set.
The flow rate control valve 1 is controlled by the controller 21 so as to maintain a constant temperature.
3 by feedback control of the heat medium flowing through the heat medium pipe 14.
An operation to control the supply amount is performed. Doing such driving
From the pressure sensor 18 and the outgassing temperature sensor 19,
Correspondence between can pressure and outgas temperature (に よ る) by input signal of
When the clerk again becomes consistent with that of the ideal state
In this case, the detection signal switching means 23 is again switched to the pressure sensor 18.
Side, and the pressure in the reduced-pressure steam generation can 11 becomes the set pressure.
The flow control valve 13 is filtered by the controller 21 so that
To control the supply amount of the heat medium flowing through the heat medium pipe 14
Perform controlled operation.

Next, when changing the flow rate (G) of the low-temperature fluid,
In this case, the detection signal switching means 23 is switched to the water temperature sensor 17 side.
In other words, the temperature of the water in the reduced pressure steam
The flow control valve 13 is turned on by the controller 21 so that
Supply amount of the heat medium flowing through the heat medium pipe 14 under feedback control
Control operation. With this operation, reduced pressure steam is generated.
The temperature of the water in the raw can 11 changes the flow rate of the changed low-temperature fluid.
When the set temperature corresponding to (G) is reached, a detection signal
The switching means 23 is switched to the pressure sensor 18 side to
Controller 2 so that the pressure in gas generating can 11 becomes the set pressure.
The feedback control of the flow control valve 13 by the
An operation for controlling the supply amount of the heat medium flowing through the pipe 14 is performed. This
At this time, the feed forward amount setting unit 24
Detection signal concerning the flow rate of LNG from the 15 controllers 22
The flow rate of the heated steam flowing through the heat medium pipe 14 is determined based on the
The controller 2 of the flow control valve 13 is calculated by calculating a signal for determining
1 to perform feedforward control. Like this
When the water temperature reaches the target value,
In the can by the input signal from 18 and the outgassing temperature sensor 19
Due to the correspondence between pressure and outgassing temperature (Θ),
It is possible to detect abnormalities in which compressible gas has accumulated
Then, the detection signal switching means 23 is again moved to the pressure sensor 18 side.
The pressure in the reduced pressure steam generation can 11 is switched to the set pressure.
The flow control valve 13 is fed by the controller 21 so that
Back control to control the supply amount of heat medium flowing through the heat medium tube 14
Driving can be performed.

As described above, the control of the decompression boiler type vaporizer of the present invention.
The method has been described with reference to one embodiment.
4 and a reduced-pressure steam generating can 1
A burner tube is arranged in 1 to transfer the heat of combustion of the combustion burner.
You may make it.

[0012]

As described above, according to the present invention, usually, cans
Instead of the control according to the water temperature, the control is conducted according to the in-can pressure
Control that greatly reduces waste and delay time.
It is strong against disturbance and stable control is possible.
Become. In addition, changes in the correspondence between can pressure and outgassing temperature (Θ)
To detect that non-condensable gas has accumulated in the can.
In this case, control from pressure in the can
Switch to control based on water temperature and perform appropriate control
Can be. When changing the flow rate of the low-temperature fluid,
Can water temperature until the set temperature corresponding to the changed flow rate is reached
The appropriate control can be performed by controlling
Wear. Thus, in the present invention, quick follow-up can always be performed.
Control and stable supply of vaporized low-temperature fluid
It works.

[Brief description of the drawings]

FIG. 1 shows a vacuum boiler type vaporizer to which the method of the present invention is applied.
FIG. 2 is a system explanatory diagram showing a configuration example.

FIG. 2 is a system explanatory diagram showing a conventional decompression boiler type vaporizer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Decompression boiler type vaporizer 11 Decompression steam generation can 12 Decompression steam can 13 Flow control valve 14 Heat medium tube 15 Flow control valve 16 Heat transfer tube 17 Water temperature sensor 18 Pressure sensor 19 Outgoing gas temperature sensor 20 Control means 21, 22 Controller 23 Detection signal switching means 24 Feed forward amount setting unit 25, 26 Differential pressure type flow rate detection means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kanji Karui, 5-5-43-211 Higashi-Terao, Tsurumi-ku, Yokohama, Kanagawa (72) Inventor, Masahiro Arakawa 4-8-3, Kosaku, Funabashi-shi, Chiba (56) Reference Reference JP-A-63-80105 (JP, A) JP-A 2-115604 (JP, U) JP-A 62-180202 (JP, U) JP-A 60-55935 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) F22B 3/04

Claims (2)

(57) [Claims] 1. A reduced-pressure steam generator in which a heat transfer pipe is provided and water is retained, and a reduced-pressure steam can connected to the reduced-pressure steam generator and provided with a heat transfer tube through which a low-temperature fluid flows are provided. provided with a pressure detection means of the vacuum vapor generating vacuum vapor generating the can and temperature detection means of the water in the can, the heat transfer tube is provided with outlet gas temperature detecting means for detecting the temperature of the vaporized cryogen, heat Adjustment of the flow control valve provided in the medium pipe
The pressure gauge communicates with the temperature detecting means through the detection signal switching means.
Selective connection with any of the force detection means
And the pressure detection means.
Correspondence relationship between each detection signal of the stage and the output gas temperature detection means
In an ideal state where non-condensable gas does not stay
Non-condensation by detecting the deviation compared to the correspondence
Configures control means for detecting stagnation of reactive gas, and usually detects
Switch the signal switching means to the pressure detecting means side, and
Adjust the controller so that the pressure inside the generator can reaches the set pressure.
Feedback control of the flow control valve to flow through the heat medium pipe
In addition to controlling the supply amount of the heat medium, the pressure detection means and the
The correspondence between the detection signals of the gas temperature detection means is ideal.
The control means detects that the correspondence has deviated from the
Output, switch the detection signal switching means to the temperature detection means side.
Switch the temperature of the water in the decompression steam generator to the set temperature.
The flow rate control valve is fed back by the controller so that
Control the supply amount of the heat medium flowing through the heat medium tube
Control method for a decompression boiler type vaporizer characterized by the following: (2) When changing the flow rate of the low-temperature fluid, the
The information signal switching means is switched to the temperature detection
Set the temperature of the water in the gas generating can according to the changed flow rate
Feed the flow control valve by the controller until the temperature reaches
Back control to control the supply amount of heat medium flowing through the heat medium tube
Also, when the set temperature is reached, the detection signal switching means
Switch to the pressure detection means side and set the pressure in the
The flow rate control valve is adjusted by the controller so that
Feedback control to control the supply amount of the heat medium flowing through the heat medium tube
The decompression boiler according to claim 1, wherein the boiler is controlled.
Control method