KR20110051731A

KR20110051731A - Cofferdam temperature control method & facility of membrane lng carrier

Info

Publication number: KR20110051731A
Application number: KR1020090108464A
Authority: KR
Inventors: 박두삼
Original assignee: 현대중공업 주식회사
Priority date: 2009-11-11
Filing date: 2009-11-11
Publication date: 2011-05-18

Abstract

The present invention relates to a membrane LNG carrier ship cofferdam temperature control method and apparatus therefor, the purpose of which is to measure the outlet temperature of the glycol water discharged from the steam heater to directly control the flow rate of steam flowing into the steam heater and through this The present invention provides a membrane LNG carrier ship cofferdam temperature control method and apparatus capable of optimizing cofferdam temperature by preventing overheating.

The present invention measures the outlet temperature of the glycol water discharged from the steam heater by a temperature sensor, and controls the flow rate of the steam flowing into the steam heater from the control unit in accordance with the measured value detected by the temperature sensor to overheat the glycol water In addition, the cofferdam temperature can be optimized.

Description

Membrane LNG carrier carrier cofferdam temperature control method and apparatus {Cofferdam Temperature Control Method & Facility of Membrane LNG Carrier}

The present invention relates to a membrane LNG carrier ship cofferdam temperature control method and apparatus therefor, by sensing the temperature of the glycol water outlet, by directly controlling the steam flow to the heater in accordance with the detection value can optimize the glycol water discharge temperature control A membrane LNG carrier ship cofferdam temperature control method and apparatus therefor.

In general, liquefied natural gas (LNG) consists mainly of methane, but also contains small amounts of other liquefied gases, although current economic interest is focused on LNG transport, problems related to the transport and handling of large quantities of liquefied gas are ammonia, ethylene The same applies to liquefied gases such as propane, butane and chlorine.

As LNG emerged as an energy resource, an efficient transportation method for transporting a large amount from the production base to the destination of the demand site was considered to use this gas as energy, and the result was an LNG carrier for maritime transportation of LNG. appear.

In LNG carriers, LNG storage tanks are built for the storage and transportation of LNG liquefied at cryogenic conditions. In these storage tanks, attention is paid to complete leakage prevention, complete insulation, and stability of low-temperature and shrinking tanks. .

In general, LNG is transported at vapor pressures slightly above atmospheric pressure and boiling temperatures of about -260 ° F (-163 ° C), and all containment systems must be constructed of materials that can withstand extremely low temperatures, and from ambient conditions to field conditions. It must be designed to have temperature insulations that are effective in accommodating a wide range of temperature changes, preventing heat ingress and preventing cooling of the ship's basic hull structure.

In general, a cofferdam (1: cofferdam) having a shape similar to the cross-sectional shape of the tank is installed before and after each storage tank T of the membrane type liquefied natural gas storage ship.

As mentioned above, LNG cargoes are stored at an extremely low temperature of -163 ° C, so if there is no heating device for temperature rise between the transverse bulkheads of the storage tank, the LNG cargo is about -50 ° C to -100 ° C by heat transfer. It is in a low temperature state, and general steel structures may be damaged by hull due to the low temperature brittleness of the material.

Eventually, a separate heating system is used to raise the air temperature of the cofferdam to at least 0 ° C to 5 ° C, and general class approved steel is used.

The heating system is a heating coil is installed in the inside of the copper dam (A), the inside of the heating coil is filled with glycol water (Glycoled Water) used as an antifreeze, the outside of the copper dam is equipped with a pump, The pump circulates inside the cofferdam (A) and pulls the cooled glycol water and sends it to the steam heater. That is, the glycol water heated from the steam heater is configured to heat the cofferdam steel structure while moving inside the cofferdam A along the heating coil.

The heating system used in the prior art, as shown in Figure 3, in order to control the temperature of the cofferdam, sense the temperature of the glycol water discharge line of the steam heater, glycol water with a 3-way valve 10 on the same line The flow rate was controlled to control the temperature of the cofferdam.

However, the conventional heating system as described above does not have a function of adjusting the amount of steam introduced into the steam heater, so that the glycol water inside the steam heater may be overheated, which makes it difficult to keep the temperature of the cofferdam constant. There was a point.

In addition, the conventional heating system requires a three-way valve 10 and a bypass line 11 to be installed for the cofferdam temperature control, which requires a lot of time to install, and a problem in maintenance due to a complicated installation structure. there was.

The present invention is to solve the above object, the object is to measure the outlet temperature of the glycol water discharged from the steam heater to directly control the flow rate of steam flowing into the steam heater and thereby prevent overheating of glycol water The present invention provides a membrane LNG carrier ship cofferdam temperature control method and apparatus for optimizing the cofferdam temperature.

It is still another object of the present invention to provide a membrane LNG carrier ship cofferdam temperature control method and apparatus which can simplify the structure, reduce material costs, and reduce production man-hours through the 3-way valve and bypass line installation. .

As such, the present invention controls the flow rate of steam flowing into the steam heater according to the glycol water outlet temperature without installing the 3-way valve and the bypass line, thereby preventing overheating of the glycol water, thereby easily optimizing the cofferdam temperature. Can be done.

In addition, the present invention can omit the installation of the 3-way valve and the bypass line, which can simplify the structure of the device, thereby reducing the installation time and can proceed quickly the work process, reducing material costs There are many effects, such as saving money.

Figure 1 shows a longitudinal cross-sectional view of the ship, Figure 2 shows an exemplary view showing a configuration according to the present invention, the present invention is glycol water filled in the heating coil inside the cofferdam is drawn up by the pump (2) In the membrane LNG carrier ship cofferdam temperature control method of moving to the steam heater (3a, 3b) and heated, the heated glycol water is moved along the heating coil in the inside of the cofferdam (A) to heat the cofferdam (1) ;

The outlet temperature of the glycol water discharged from the steam heaters 3a and 3b is measured by the temperature sensor 4 and the steam heater 3a is controlled by the controller 5 according to the measured value detected by the temperature sensor 4. By controlling the flow rate of the steam flowing into the 3b), while preventing overheating of the glycol water, the temperature of the cofferdam 1 is maintained by maintaining a constant temperature of the glycol water discharged from the steam heaters 3a and 3b. It can be optimized.

The glycol water refers to ethylene glycol, which is a nonvolatile liquid boiling at 197 ° C., is a viscous, sweet colorless liquid, and absorbs moisture well.

The steam heaters 3a and 3b heat the glycol water by the supplied steam flow rate, and are installed on the glycol water line 6, and the main steam heater 3a and the preliminary steam heater 3b are respectively installed. It is.

The temperature sensor 4 is installed in the outlet side line 7 discharged from the steam heaters 3a and 3b, and measures the temperature of the glycol water in the outlet side line 7 of the steam heater, respectively, and the measured measurement. The value is input to the controller.

The control unit 5 may utilize a control unit that is conventionally used or may further install a separate control unit, and on the steam supply line 9 connected to the steam heaters 3a and 3b according to the measured value of the temperature sensor 4. By controlling the steam supply valve (8) to control the steam flow rate in real time.

As described above, the membrane LNG carrier ship cofferdam temperature control apparatus of the present invention circulates the inside of the cofferdam (A) and the cooled glycol water steam heaters (3a, 3b) by the steam supplied through the steam supply line (9) Glycol water heated by the steam heaters 3a and 3b is moved to the inside of the cofferdam through the steam heater outlet line 7 and the cofferdam steel structure is heated. A cofferdam temperature control device;

The temperature sensor 4 is installed in the outlet line 7 of the steam heater, the control unit 5 is connected to the temperature sensor 4, and the steam supply valve 8 driven by the control unit 5 is steam. It is intended to be installed in the supply line (9).

Hereinafter, the present invention will be described in detail by way of examples.

Example 1

The glycol water temperature of the glycol waterline on the outlet side of the steam heater was measured, and the flow rate of steam flowing into the steam heater was controlled according to the measured value, and the cofferdam temperature was measured according to the result. In this case, the steam heater was measured for the main steam heater of the heating system having a main steam heater and a preliminary steam heater, the results are shown in Table 1 below.

Table 1

Example 2

The glycol water temperature of the glycol waterline on the outlet side of the steam heater was measured, and the flow rate of steam flowing into the steam heater was controlled according to the measured value, and the cofferdam temperature was measured according to the result. In this case, the steam heater was measured for the preliminary steam heater of the heating system having a main steam heater and a preliminary steam heater, the results are shown in Table 2 below.

[Table 2]

As in Examples 1 and 2, it can be seen that the heating system according to the present invention can control the cofferdam temperature in almost real time.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a longitudinal cross-sectional schematic diagram of a ship

2 is an exemplary view showing a configuration according to the present invention

3 is an exemplary view showing a conventional configuration

DESCRIPTION OF THE REFERENCE NUMERALS

(1): copper dam (2): pump

(3a, 3b): Steam heater (4): Temperature sensor

(5): control unit (6): glycol waterline

(7): Outlet line (8): Steam supply valve

(9): Steam supply line

Claims

The outlet temperature of the glycol water discharged from the steam heater is measured by a temperature sensor, and the control unit controls the flow rate of steam flowing into the steam heater from the controller according to the measured value detected by the temperature sensor to prevent overheating of the glycol water. At the same time, the cofferdam temperature control method and apparatus for a membrane LNG carrier, characterized in that the cofferdam temperature can be optimized.

The inside of the cofferdam is circulated and the cooled glycol water is heated in the steam heater by steam supplied through the steam supply line, and the glycol water heated by the steam heater is re-coffered through the steam heater outlet line. In the membrane LNG carrier ship cofferdam temperature control device is moved to the inside (A) to heat the cofferdam steel structure;

A temperature sensor is installed in the outlet line of the steam heater, the control unit is connected to the temperature sensor, the steam LNG supply line cofferdam temperature control device, characterized in that the steam supply valve driven by the control unit is installed in the steam supply line.