KR20060074117A - Gas heater with vacuum steam heating type - Google Patents

Abstract

The present invention relates to a vacuum heated gas heater used in a supply control station, and more particularly, a furnace passage provided inside an outer body of the gas heater; An association connected with the furnace to induce exhaust gas; A first connecting pipe connected to one side of the lower portion of the outer cylinder; An economizer connected to the first connection pipe and formed in an independent configuration to the outside of the outer body provided to exchange heat with the working fluid filled therein; A second connecting pipe connected to one side of the economizer, the second connecting pipe being connected to the intermediate portion of the outer cylinder; It relates to a vacuum heating gas heater comprising a heat exchanger for heating natural gas formed on the outer body.

 The present invention relates in particular to a heat exchange method and structure including an economizer provided on the outside of a vacuum gas heater, and improves the safety of the device by reducing the heat transfer area and suppressing corrosion by the heat exchange efficiency of the high pressure natural gas heat exchanger. By changing the structure, the latent heat of the combustion gas array is recovered to cope with the supply gas load in the range of 15: 1, maintaining high thermal efficiency in the entire load area, reducing the gas heater operating cost, and improving the durability and maintenance of the equipment. It is convenient and the pressure loss on the combustion gas side is characterized in that it can reduce noise and vibration.

Gas Heater, Decompression Steam, Vacuum, Heat Exchanger, Economizer

Description

Gas heater with vacuum steam heating type

1 is a schematic view showing a vacuum heated gas heater according to the present invention,

2 is a schematic view showing an associated economizer of a vacuum heating gas heater according to the present invention;

3 is a schematic view showing a water pipe type economizer of a vacuum heating gas heater according to the present invention;

Figure 4 is a schematic diagram showing the internal heat transfer state of the vacuum heating gas heater according to the present invention.

<Description of Symbols for Main Parts of Drawings>

1: burner and blower 2: associated

3: 1st connector 4: economizer

5: communication 6: heat exchanger

7: External body 8: Roton

9: flange 10: second connector

11: connection 12: baffle

13: vacuum sensor 14: vacuum pump

15: safety valve 16: gas detection unit

17: circulation pump 18: heat exchanger header

The present invention relates to a vacuum heated gas heater used in a supply control station, and more particularly, a furnace passage provided inside an outer body of the gas heater; An association connected with the furnace to induce exhaust gas; A first connecting pipe connected to one side of the lower portion of the outer cylinder; An economizer connected to the first connection pipe and formed in an independent configuration to the outside of the outer body provided to exchange heat with the working fluid filled therein; A second connecting pipe connected to one side of the economizer, the second connecting pipe being connected to the intermediate portion of the outer cylinder; It relates to a vacuum heating gas heater comprising a heat exchanger for heating natural gas formed on the outer body.

In the prior art, the purpose of operating a gas heater used by a natural gas supply control center is to reduce the pressure of a gas supplied from an LNG takeover base to a constant pressure in order to supply power to a power plant and a city gas company. In order to prevent the low temperature damage to the downstream equipment of the constant pressure, the gas heater is installed and operated in front of the constant pressure in order to preheat the gas upstream of the constant pressure.

However, in the case of the gas heater currently in operation, since the heat exchange method adopts the natural convection method, the flow rate of the intermediate heat medium is not large, resulting in corrosion of the heat exchanger tube for high pressure gas such as gap corrosion caused by stagnation in the tube of the heat exchanger. Due to this, the tube thickness is reduced, and thus maintenance management such as equipment replacement is required to increase the stability of the high-pressure gas supply equipment, and a combustion furnace and an economizer, which is a heat exchanger side of the gas heater combustion gas, are installed inside the equipment, and the load fluctuation of the supply gas is changed. The design and manufacture of this large gas heater is based on the maximum capacity, so it is difficult to repair and repair the equipment due to the corrosion of the exhaust gas side heat exchanger due to the exhaust gas condensation at the low load operated under the maximum load even if the proper efficiency is maintained at high load. Operation at high load due to deterioration of efficiency at high load and combustion noise and vibration Difficult problems arise.

The present invention has been made to solve such a problem, in terms of device efficiency, the heat transfer experiment is carried out in a natural convection method (conventional method) and the vacuum heating method to be implemented in the present invention for the gas heater having the same structure and heat transfer area As a result, the thermal efficiency rises about 7-8% at high loads, and the heat exchange efficiency of the natural gas heat exchanger is about 2--8% higher than that of the existing natural convection method as the heat transfer method is changed. It increased 2.5 times, resulting in a reduction in heat transfer area.

  In terms of the maintenance of the natural gas heat exchanger, it is difficult to remove dissolved oxygen even during the operation of the conventional method in the range of 50-70 ℃, and the dissolved oxygen is high when the device is stopped, and the corrosion inhibitor is continuously added and managed. Required.

In addition, when dissolved oxygen is present in the intermediate heat medium, iron is eluted by the corrosion reaction, and corrosion progresses. Pitting and corrosion of natural gas heat exchanger due to the gap corrosion due to the difference in oxygen concentration between the corrosion area and the surrounding fluid. Due to the installation of baffles to prevent vibration, crevice corrosion occurs at the baffle and tube contacts, which deteriorates the safety of the heat exchanger of the natural gas heat exchanger with high pressure of 70kg / ㎠, but maintains vacuum in the case of vacuum heating method. Hazards can significantly slow the progress of corrosion reactions by removing the air inside the device and removing dissolved oxygen in the intermediate heat medium, and improve the safety of the device.

In the combustion furnace and economizer, the existing gas heater is installed inside the equipment by installing the combustion furnace and economizer, and when repairing the equipment, the entire associated heat exchanger is repaired separately from the equipment. Maintenance is difficult because work is possible, but when economizer is installed separately from device, maintenance work is easy.

Due to the seasonal fluctuation of natural gas supply flow, there is a problem of noise and vibration caused by corrosiveness due to exhaust gas condensation at low load and large back pressure at high load during actual gas heater operation, but economizer is separated from main body and combustion gas The efficiency of the device is increased by inducing condensation in the economizer, and the economizer can be centrally managed using materials that are highly resistant to corrosion.

Hereinafter, a vacuum heating gas heater according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view showing a vacuum heated gas heater according to the present invention, which will be described in detail.

      A furnace (8) provided inside the outer body (7) of the gas heater; An association (2) connected to the furnace (8) to induce exhaust gas; A first connecting pipe connected to one side of the lower portion of the outer cylinder (7); An economizer (4) connected to the first connection pipe (3) and formed in an independent configuration to the outside of the outer body provided for heat exchange with a working fluid filled therein; A second connecting pipe 10 connected to one side of the economizer 4 and provided to be connected to an intermediate portion of the outer cylinder 7; It is a vacuum heating gas heater including a heat exchanger 6 for heating natural gas formed on the outer body.

Here, the heat exchange unit 6 for heating natural gas is made of a shell tube type or a plurality of tubes, and natural gas is introduced into the inlet of the heat exchange unit and heated to the outlet.

The economizer 4 may be a heat exchanger having an associated or water pipe type as shown in FIGS. 2 and 3 as heat exchange between the combustion flue gas and the intermediate heat medium.

 The first connecting pipe 3 and the second connecting pipe 10 is made to be easily removable by the connecting portion (11).

Figure 2 is a schematic diagram showing the internal heat transfer state of the vacuum heating gas heater according to the present invention, the operation principle according to the present invention described above are as follows.

The present invention is a vacuum heating gas heater, the pressure inside the outer cylinder (7) is always maintained at a pressure below the large company, in the case of water used as the working fluid of the intermediate heat medium using the principle that the boiling temperature is lowered as the operating pressure is lowered It is a device that heats natural gas through evaporation and condensation.

In order to discharge the non-condensable gas present in the gas heater to maintain a vacuum state, a vacuum pump 14 is provided outside the outer cylinder 7, and the degree of vacuum inside the gas heater is sensed to detect the vacuum pump 14. As a relay device for operating the required vacuum pressure to maintain the required vacuum pressure to detect the temperature difference between the gas and liquid portion of the intermediate heat medium to detect the degree of vacuum or to operate the vacuum pump 13 above the set pressure the outer cylinder (7) ) It is installed on the outside to maintain high heat transfer efficiency, and when the internal pressure of the device leaks high pressure natural gas from the natural gas heating heat exchanger, the safety valve 15 is installed outside the outer cylinder 7 to protect the device. The heat transfer efficiency and safety of the heater can be improved.

In order to recover the sensible and latent heat, which are the final stages of the exhaust gas heat recovery, which is delivered to the intermediate heat medium in the pipe (2), a tube of the economizer (4) formed in the form of a plurality of heat exchange tubes is installed outside the gas heater, and the lower part of the outer cylinder (7) The first connecting pipe 3 is provided on the side and the lower side of the economizer 4, and the second connecting pipe 10 is formed on the upper side of the economizer 4 and the middle of the outer cylinder 7. In addition, the first connection pipe 3 and the second connection pipe 10 are fastened by a connection part 11, and the economizer is easily connected to the economizer and the combustion gas outlet side by a flange 9, thereby making it easy to repair or replace the economizer. It is composed of a structure.

The economizer (4) the internal structure can be configured in a structure capable of heat exchange of various types in which the exhaust gas and the intermediate heat medium can be heat-exchanged, when the exhaust gas and the intermediate heat medium is heat-exchanged when the associated or water pipe heat exchanger structure is applied It is a structure that allows natural circulation by changing density due to boiling of intermediate heat medium in the process.

The economizer (4) is a part for finally recovering the exhaust gas heat generated from the associative (2) until latent heat, so the possibility of corrosion caused by the exhaust gas condensation is very high, so that the decomposition and maintenance is easy and the material is also a gas heater It is possible to choose a material that is resistant to corrosion and other material materials.

In the gas heater according to the present invention, a gas heater having the same structure and heat transfer area is subjected to a heat transfer test using a natural convection method (conventional method) and a vacuum heating method according to the present invention. As the heat exchange efficiency of the natural gas heat exchanger 6 changes the heat transfer method, the heat exchange efficiency of the natural gas heat exchanger 6 is about 2 to 2.5 compared to the existing natural convection method. As a result of the increase, heat transfer area was reduced.

In the case of the prior art, it is difficult to remove dissolved oxygen even during the operation of the maintenance operation temperature of the natural gas heat exchanger 6 in the range of 50 to 70 ° C., and the dissolved oxygen is high when the device is stopped. Is required.

In addition, when dissolved oxygen is present in the intermediate heat medium, iron is eluted by the following corrosion reaction, and corrosion proceeds, pitting due to gap corrosion due to the difference in oxygen concentration between the corrosion area and the surrounding fluid, and for natural gas Due to the installation of baffles to prevent vibration of the heat exchanger (6), gap corrosion occurs at the baffle and the heat exchanger tube contact portion, which deteriorates the safety of the high-pressure tube bundle with a natural gas supply pressure of 70 kg / ㎠ In the case of the heating method, the rate of corrosion reaction can be significantly slowed down and the safety of the device can be improved by removing air inside the device and removing dissolved oxygen in the intermediate heat medium.

In the case of the conventional gas heater, since the combustion furnace and economizer are installed inside the equipment, the entire tube is repaired separately from the equipment when the equipment is repaired, and the tube (2) and economizer (4) tubes are repaired. Maintenance is difficult because work is possible outside the city, but maintenance work is easy when the economizer (4) is separated from the equipment.

There is a problem of noise and vibration caused by corrosiveness due to exhaust gas condensation at low load and large back pressure at high load during actual gas heater operation due to severe change of natural gas supply flow rate by season, but economizer (4) Separating and inducing the condensation of the combustion gas to occur in the economizer part 4 increases the efficiency of the device, and centralizes the economizer 4 using materials that are highly resistant to corrosion, maintenance and economizers. (4) It is easy to replace and it is possible to increase the efficiency of gas heater and reduce the maintenance cost.

In addition, it is possible to increase the heat exchange capacity of the economizer 9 by mounting the circulation pump 17 in the first connecting pipe 3 to increase the circulation flow rate of the intermediate heat medium.

As described above, the vacuum heating gas heater according to the present invention includes the following effects.

By keeping the inside of the device in a vacuum to prevent corrosion and improve heat exchange efficiency inside the gas heater, dissolved oxygen in the intermediate heat medium is removed to prevent corrosion progress inside the device, reducing device life and maintenance costs. As the heat exchange process is heat transfer by evaporation and condensation due to the phase change temperature of the intermediate heat medium, the heat transfer efficiency is higher than that of the existing natural convection method, which reduces the heat transfer area and improves the efficiency of the natural gas heat exchanger. .

In addition, the combustion gas-side heat exchanger structure is installed in a furnace, plumbing, and economizer integrally inside the equipment to reduce the exhaust gas temperature inside the equipment by installing a combustion chamber and plumbing inside the equipment and installing an economizer outside the equipment. The combustion furnace outlet temperature is maintained above the exhaust gas condensation temperature even under load operation, and the heat exchanger repair and replacement cycle due to the exhaust gas condensation is longer than the existing method. For this purpose, various heat exchangers such as shell tubes are installed outside the equipment to maintain a constant exhaust gas outlet temperature during low load and high load operation, and condensate and recover the combustion gases in the full load range for maximum equipment efficiency.

In addition, it is possible to concentrate the management by inducing the combustion gas to be condensed in the economizer, and the maintenance is easy by separating and repairing the economizer during maintenance. It is possible to suppress the noise and vibration of the gas heater caused by the increase of the pressure loss on the side.

Claims (5)

A furnace (8) provided inside the outer body (7) of the gas heater; An association (2) connected to the furnace (8) to induce exhaust gas; A first connecting pipe 3 connected to a lower portion of the gas heater outer cylinder 7; An economizer (4) connected to the first connection pipe (3) and provided to exchange heat between the intermediate heat medium and the exhaust gas filled therein; A heat exchange part 9 formed on the outer body 7 to heat natural gas; Vacuum heating gas heater, characterized in that it comprises a second connecting pipe (10) which is connected to one side of the economizer (4) and is connected to the heat exchange unit (9). A furnace (8) provided inside the outer body (7) of the gas heater; An association (2) connected to the furnace (8) to induce exhaust gas; A first connecting pipe 3 connected to the lower portion of the gas heater outer cylinder 7; An economizer (4) connected to the first connection pipe (3) and provided to exchange heat between the intermediate heat medium and the exhaust gas filled therein; A heat exchange part 9 formed on the outer body 7 to heat natural gas; The second connection pipe 10 is connected to one side of the economizer 4 and is provided to be connected to the heat exchanger 9, and discharges the non-condensable gas present in the gas heater to maintain a vacuum state. The vacuum pump 14 and the relay device for driving the vacuum pump 14 by sensing the vacuum degree inside the gas heater to detect the temperature difference between the gas and liquid portion of the intermediate heat medium to detect the vacuum degree or more than the set pressure Vacuum heated gas heater including a vacuum sensing device (13) for driving a vacuum pump and a safety valve (15) for protecting the device when natural gas of high pressure leaks from the natural gas heating heat exchanger. . The method according to claim 1 or 2, The inside of the economizer 4 is a heat exchanger type in which the flue gas and the intermediate heat medium are heat-exchanged, and is formed in the heat exchanger type of an associated or water pipe type. The intermediate heat medium is heated and the combustion gas is discharged to the outside through the communication (5), the intermediate heat medium flows in from the first connection pipe and is heated by the combustion gas, and naturally flows into the outer cylinder through the second connection pipe by buoyancy. Vacuum heated gas heater, characterized in that circulated. The method according to claim 1 or 2, Association (2) The outlet side and the connection between the stack (5) and the economizer (4) are connected by a flange (9) and the first connector (3) and the second connector (10) are connected by a connector (11). Vacuum heating type gas heater, characterized in that provided to facilitate removal. The method according to claim 1 or 2, Vacuum heating gas heater, characterized in that the circulation pump 17 is mounted on the first connecting pipe (3) for forced circulation of the exhaust gas.

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