JPH06341602A - Pressure reducing boiler type vaporizer and control thereof - Google Patents

Abstract

PURPOSE:To provide a pressure reducing boiler type vaporizer stable and good in control responsiveness. CONSTITUTION:A pressure reduced steam generating boiler 11 and a pressure reduced steam boiler 12 are installed in communication with each other and a heating medium pipe 14 for passing steam therethrough is provided in the pressure reduced steam generating boiler 11. A heat transfer pipe 16 for passing LNG into the pressure reduced steam boiler 12 is provided. The water temperature and pressure in the pressure reduced steam generating boiler 11 and the outlet gas temperature of LNG in the heat transfer pipe 16 are detected and the interior temperature of the boiler, the flow amount of LNG and the outlet gas temperature in an ideal condition are judged by comparison and, if any deviation is detected, a non-condensable gas can be considered to be mixed in the boiler. When the non-condensable gas is mixed, since the judgement by comparison is stopped and since a detection signal switching means 23 is switched to effect feed-back control based on the detection signal from a water temperature sensor 18, there is no possibility of erroneous judgement and this method provides a good control responsiveness as well as stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum boiler type vaporizer and a control method thereof.

[0002]

2. Description of the Related Art Recently, LNG (liquefied natural gas) is rapidly expanding as an energy source with little pollution. L
NG is a natural gas containing methane (CH ₄ ) as a main component, cooled to an extremely low temperature and liquefied. Once stored in an LNG storage facility or the like, this is introduced into a vaporizer and supplied for various purposes. It is supposed to do. As the LNG vaporizer, there are a LNG heating source that uses seawater, river water, and the like, and a device that uses combustion heat of LNG and the like. Furthermore, a vaporizer of a type using an intermediate heat medium has been devised. An example of this system is a decompression boiler type vaporizer. The decompression boiler type vaporizer 1 applies low-temperature steam in a decompressed state as an intermediate heat medium. As shown in FIG. 2, the decompression steam generation can 2 and the decompression steam can communicating with the decompression steam generation can 2. 3, the reduced pressure steam generating can 2 is provided with a heat medium pipe 4 in which heating steam is circulated, and water is retained therein, while LNG is circulated in the reduced pressure steam can 3. A heat transfer tube 5 is arranged.
The reduced pressure steam generating can 2 and the air in the reduced pressure steam can 3 communicating with the reduced pressure steam generating can 2 are sucked by a vacuum pump (not shown) to reduce the pressure,
The water in the reduced pressure steam generating can 2 is vaporized into a low temperature by the heating medium pipe 4 in which the heating vapor is circulated, and the LNG flowing in the heat transfer pipe 5 is vaporized by the low temperature vapor. In the decompression boiler type vaporizer 1, the temperature of the water in the decompression steam generator can 2 is detected, the steam flowing into the heat medium pipe 4 is adjusted, and the temperature of the water in the decompression steam generator can 2 is set to the set temperature. Therefore, the temperature is controlled.

[0003]

However, in the temperature control system in the decompression boiler type vaporizer 1 as described above, the change in the water temperature in the decompression steam generator can 2 is that the heat capacity of the decompression steam generator can 2 itself is large. Since the temperature detection means has a detection delay, both the dead time and the time constant are large, and it takes too much time until the control is stabilized after the disturbance is introduced. Further, in the method of detecting and controlling the pressure in the reduced pressure steam generation can 2, when the non-condensable gas stays, the correspondence relationship between the temperature of the water in the reduced pressure steam generation can 2 and the pressure is broken, and the temperature of the vaporized LNG is decreased. There is a risk of lowering. The present invention has been made in view of such problems,
It is an object of the present invention to provide a decompression boiler type vaporizer and a control method thereof that are stable and enable good control with good responsiveness.

[0004]

In order to solve the above-mentioned problems, the present invention provides a reduced pressure steam generating can in which a heat medium pipe is arranged and water is retained, and a low temperature steam generating can which is in communication with the reduced pressure steam generating can. A reduced pressure steam can provided with a heat transfer tube for circulating a fluid is provided, and while the temperature detection means of water in the reduced pressure steam generation can and the pressure detection means in the reduced pressure steam generation can are provided, the heat transfer tube is vaporized. A means for detecting the temperature of the low-temperature fluid is provided to detect the temperature of the low-temperature fluid. ,
It is characterized in that a control means for detecting an abnormal state is provided as compared with the relationship of the low temperature fluid inlet temperature. Further, the present invention detects the water temperature in the reduced pressure steam generating can, the pressure in the reduced pressure steam generating can and the pressure in the reduced pressure steam can, and the outlet gas temperature, and performs feedback control based on the detection signal related to these water temperature and pressure. It is characterized in that retention of the non-condensable gas is detected by comparing a detection signal concerning the output gas temperature and pressure with the relationship between the output gas temperature and pressure under an ideal state to detect a deviation. Furthermore, in the present invention, when retention of non-condensable gas is detected in the reduced pressure steam generation can and in the reduced pressure steam can, until the water temperature in the reduced pressure steam generation can reaches a target value, a detection signal relating to the water temperature is detected. It is characterized in that feedback control is performed based on this.

[0005]

The relationship between the temperature and the pressure in the reduced pressure steam generating can and in the reduced pressure steam can can be represented by a saturated vapor pressure curve. Further, between the temperature in the can (Θs), the flow rate of the low temperature fluid (G), the temperature of the discharged gas (Θ) and the temperature of the low temperature fluid inlet (Θi), Θ = (1-f (G)) Θs + f (G) Θi The following relationship is established (however, f (G) is a monotonically increasing function having the heat transfer area as a parameter). Therefore, these elements are stored as values in an ideal state (a state where the inside of the can is filled with steam), and the respective values during operation of the apparatus are obtained to obtain the ideal state. It is possible to determine that there is an abnormal state (for example, non-condensable gas is mixed) by detecting the deviation by comparing with the value in. When it is determined that the non-condensable gas is mixed, the exhaust is performed and the temperature inside the reduced pressure steam generating can and the inside of the reduced pressure steam can are controlled to a predetermined temperature. In addition, each element (for example, the flow rate of the cryogenic fluid)
When (G)) is changed, the control is executed so that each of the other elements has a value corresponding to the flow rate (G) of the low temperature fluid. At that time, until the temperature inside the can (Θs) reaches a predetermined temperature, the comparison judgment with the values of each element in the ideal state described above is stopped, and the temperature of the water inside the depressurized steam generation can reaches the target value. In such a case, the above-mentioned comparison judgment is made again.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a decompression boiler type carburetor and a control method according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 10 indicates a decompression boiler type carburetor, and this decompression boiler type carburetor 10 comprises a reduced pressure steam generating can 11 and a reduced pressure steam can 12 in communication with each other and a vacuum pump (not shown) inside the can. ) To reduce the exhaust pressure, heat the water stored in the depressurized can to generate low-temperature steam, and use this steam as a heating source for LNG vaporization. The reduced pressure steam generating can 11 is arranged so that a heating medium pipe 14 in which heating steam is circulated through a flow rate control valve 13 passes through the stored water. On the other hand, the reduced pressure steam can 12 contains LNG.
A heat transfer tube 16 is provided to allow the heat transfer tube 16 to flow through the flow rate control valve 15. In addition, in the reduced pressure steam generating can 11,
A water temperature sensor 17 for detecting the temperature of water in the reduced pressure steam generating can 11 and a pressure sensor 18 for detecting the pressure in the reduced pressure steam generating can 11 are provided. Further, the heat transfer tube 16 is provided with an outlet gas temperature sensor 19 for detecting the temperature of the vaporized LNG. The detection signals from the water temperature sensor 17, the pressure sensor 18, and the gas temperature sensor 19 are taken into the control system 20. Based on the detection signal, the control system 20 determines the can temperature (Θs), the low temperature fluid flow rate (G), the outlet gas temperature (Θ) and the LNG inlet temperature (Θ) in an ideal state.
If a deviation is detected by performing a comparison judgment with i), it is determined that there is an abnormal state and feedback control is performed. In the reduced pressure steam generating can 11 and the reduced pressure steam can 12, in an ideal state, the temperature inside the can (Θs), the low temperature fluid flow rate (G), the outlet gas temperature (Θ) and the low temperature fluid inlet temperature.
Since (Θi) has a relationship of Θ = (1−f (G)) Θs + f (G) Θi, the control system 20 sets the value of each element to the value of another element corresponding to that value. Can be stored in advance and means for comparing the stored value with the value detected during the actual operation, and the above-described comparison / determination can be executed. Further, the control system 20 performs the arithmetic processing of the relational expression from the value detected at the time of driving to derive the values of other elements, and the derived values and the other elements detected at the time of driving. It is also possible to adopt a configuration in which the procedure of comparing with the detected value is executed. The flow rate control valve 13 in the heat medium tube 14 and the flow rate control valve 15 in the heat transfer tube 16 are provided with controllers 21 and 22, respectively, and the controllers 21 and 22 are signals from the differential pressure detector related to the flow rate. The value converted into the set value is compared with the set value, the result is calculated, and then a signal for adjusting the valve opening of the flow rate adjusting valves 13 and 15 is sent as an operation signal to continuously adjust and control the valve opening. It is a thing. The controller 2
1 is electrically connected to the water temperature sensor 17 and the pressure sensor 18 via the detection signal switching means 23, while the controller 22 of the flow rate control valve 15 in the heat transfer tube 16 corresponds to the inflowing LNG flow rate. Further, it is electrically connected to the feedforward amount setting unit 24 that calculates a signal that determines the flow rate of the heated steam flowing into the heat medium pipe 14. Further, the feedforward amount setting unit 24 is electrically connected to the controller 21 of the flow rate control valve 13 in the heat medium pipe 14.

In the pressure reducing boiler type carburetor 10 and the control method as described above, the temperature inside the pressure reducing steam generator can 11 and the pressure reducing steam can 12 (Θs), the low temperature fluid flow rate
(G), outlet gas temperature (Θ) and low temperature fluid inlet temperature (Θi)
Based on the relationship of Θ = (1-f (G)) Θs + f (G) Θi between these values, these elements are stored in a storage means (not shown) constituting the control system 20 as values in an ideal state. It is stored and compared with a detection signal detected during the operation of the decompression boiler type carburetor 10 and the stored value, and a deviation is detected to detect an abnormal state (for example,
Non-condensable gas is mixed in). When it is determined that the non-condensable gas is mixed, the control system 20 exhausts the gas and at the same time controls the detection signal switching means 23 to supply the detection signal from the water temperature sensor 17 to the controller 21. , Reduced pressure steam generator can 1
Temperature control is performed so that the temperature in 1 and in the reduced pressure steam can 12 is set to a predetermined temperature. Further, when the above-mentioned respective elements (for example, the flow rate (G) of the low temperature fluid) are changed, the control is executed so that the other elements are set to values corresponding to the flow rate (G) of the low temperature fluid. At that time, the control system 20 stops the comparison and judgment with the values of the respective elements in the ideal state described above until the temperature inside the can (Θs) reaches a predetermined temperature, and controls the detection signal switching means 23 to switch, Feedback control is executed based on the detection signal from the water temperature sensor 17. At this time, the feedforward amount setting unit 24 sets the heat transfer tube 16
The feedforward control is performed based on the detection signal related to the flow rate of LNG from the controller 22 of the flow rate control valve 15 in. That is, the feedforward amount setting unit 2
Reference numeral 4 calculates a signal that determines the flow rate of the heating steam flowing through the heat medium pipe 14, sends it to the controller 21 of the flow rate control valve 13 in the heat medium pipe 14, and adjusts the heating steam flowing into the heat medium pipe 14. Then, execute the procedure to adjust the water temperature to the target value. When the water temperature reaches the target value, the control system 20 again makes a comparison judgment with the can temperature (Θs), the low temperature fluid flow rate (G), the outlet gas temperature (Θ) and the low temperature fluid inlet temperature (Θi) in the ideal state. To execute.

The decompression boiler type carburetor and the control method therefor according to the present invention have been described above with reference to an embodiment. In addition to the structure in which heating steam is circulated in the heat medium pipe 14, the decompression steam generator can 11 is also provided. A burner tube may be arranged in the above to transfer the combustion heat of the combustion burner.

[0009]

As described above, according to the present invention, it is possible to perform control in which waste and delay time are significantly shortened as compared with the procedure of only temperature control, so that stable control is possible against disturbance. Is possible. Also, when the flow rate of the low temperature fluid is changed, once the comparison judgment with the relation between the temperature inside the can, the low temperature fluid flow rate, the outlet gas temperature, and the low temperature fluid inlet temperature is stopped, and the water temperature reaches the target value, Since the comparison determination is executed again, there is no possibility of making an erroneous determination, rapid follow-up is always possible, and stable supply of the vaporized low-temperature fluid becomes possible.

[0010]

[Brief description of drawings]

FIG. 1 is a system explanatory view showing a decompression boiler type vaporizer according to the present invention.

FIG. 3 is a system explanatory view showing a conventional decompression boiler type carburetor.

[Explanation of symbols]

 10 Decompression boiler type vaporizer 11 Decompression steam generator can 12 Decompression steam can 13 Flow rate control valve 14 Heat transfer medium pipe 15 Flow rate control valve 16 Heat transfer pipe 17 Water temperature sensor 18 Pressure sensor 19 Outlet gas temperature sensor 20 Control system 21, 22 Regulator 23 Detection signal switching means 24 Feedforward amount setting unit

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[Procedure amendment]

[Submission date] February 26, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

FIG. 2 is a system explanatory view showing a conventional decompression boiler type carburetor.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Delete

(72) Inventor Kanji Whalei 5-5-43- 211 Higashiterao, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture (72) Masahiro Arakawa 4-8-3 Old Works, Funabashi City, Chiba Prefecture

Claims (3)

[Claims] 1. A reduced pressure steam generating can, which is provided with a heat medium pipe and retains water, and a reduced pressure steam can, which is connected to the reduced pressure steam generating can and is provided with a heat transfer pipe for circulating a low temperature fluid, On the other hand, the temperature detection means for detecting the temperature of water in the reduced pressure steam generating can and the pressure detection means for detecting the pressure inside the reduced pressure steam generating can are provided. An abnormal state is detected by comparing the detection signals of the temperature detecting means, the pressure detecting means and the outlet gas temperature detecting means with the relationship among the temperature inside the can, the low temperature fluid flow rate, the outlet gas temperature and the low temperature fluid inlet temperature in the ideal state. A decompression boiler type vaporizer characterized in that a control means is provided. 2. The water temperature in the reduced pressure steam generation can, the pressure in the reduced pressure steam generation can and the pressure in the reduced pressure steam can, and the temperature of the discharged gas are detected, and feedback control is performed based on the detection signals relating to these water temperature and pressure. A decompression boiler characterized by detecting non-condensable gas retention by detecting deviations by comparing detection signals related to gas temperature and pressure with the relationship between gas temperature and pressure under ideal conditions. Control method of a carburetor. 3. When the non-condensable gas retention is detected in the depressurized steam generating can and the depressurized steam can according to claim 1, the water temperature in the depressurized steam generating can is increased until it reaches a target value. A method of controlling a decompression boiler type carburetor, characterized by performing feedback control based on such a detection signal.