Skid-mounted heat exchanger for LNG cold energy ice making

Abstract

The invention discloses a skid-mounted heat exchanger for LNG cold energy ice making. The skid-mounted heat exchanger comprises a first heat exchanger body, a second heat exchanger body, a refrigerant circulation pipeline and a heating medium circulation pipeline. The outer side of the first heat exchanger shell comprises a liquefied natural gas inlet, a natural gas outlet, an ethylene glycol water solution inlet and an ethylene glycol water solution outlet. An LNG runner, an EG runner and an intermediate medium runner are arranged in the first heat exchanger shell. An NG inlet, an NG outlet, an EG inlet and an EG outlet are formed in the outer side of a shell of the second heat exchanger, and an NG runner and an EG runner are arranged in the second heat exchanger. An NG outlet of the first heat exchanger is connected with an inlet of the second heat exchanger NG through a refrigerant circulation pipeline, and an inlet of the first heat exchanger EG is connected with an inlet of the second heat exchanger EG through a heating medium pipeline. The first heat exchanger and the second heat exchanger are both of a shell-and-tube heat exchanger structure. The gasifier disclosed by the invention has the characteristics of high corrosion resistance, low maintenance investment and long service life.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchangers, in particular to a skid-mounted heat exchanger used for making ice using LNG cold energy. Background Art

[0002] In recent years, natural gas has played an increasingly important role in global energy with its advantages of high efficiency, cleanliness, economy and safety. Liquefied natural gas (LNG) is easy to store and transport, flexible and efficient. In recent years, its share in my country's natural gas supply has increased year by year, becoming one of the important components to ensure my country's natural gas supply. Before use, LNG needs to be gasified into room temperature gas. Traditional LNG gasification stations release LNG cold energy into the surrounding environment through air-temperature gasifiers or water-bath gasifiers, which not only causes energy waste, but also causes cold pollution to the local environment. Therefore, the use of LNG cold energy has become indispensable.

[0003] LNG low temperature heat transfer equipment is the core equipment to ensure LNG gasification and recover LNG cold energy. Currently, there are three main types of equipment developed for LNG cold energy heat exchange: open rack vaporizer (ORV), water bath vaporizer (SCV) and intermediate medium heat exchanger (IFV). Intermediate medium heat exchanger has the advantages of not easy to freeze, high heat exchange efficiency and easy control, and is widely used.

[0004] Traditional intermediate medium heat exchangers are usually composed of evaporators, condensers, and thermostats, all of which are usually shell and tube heat exchangers. In traditional intermediate medium heat exchangers, the evaporator and condenser are connected in series, and the heat exchange tubes in the evaporator are all straight tube sections, which have the problems of large floor space, large heat exchange area, and high equipment cost. There is no guide plate installed inside the traditional intermediate medium heat exchanger, resulting in uneven heat exchange of the heat exchange tubes in the condenser. In addition, when the traditional intermediate medium heat exchanger is installed under sloshing conditions such as sea conditions, the evaporator heat exchange tubes may "dry burn" and the condenser heat exchange tubes may be wetted, affecting the heat exchange rate of the two parts of the heat exchanger. The traditional intermediate medium heat exchanger uses seawater as a heat medium to transfer cold energy to the surrounding environment, and does not achieve the effect of LNG cold energy recovery and utilization, resulting in a large amount of energy waste. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a skid-mounted heat exchanger for LNG cold energy ice making, which is used to recycle a large amount of cold energy released when LNG is vaporized. It has the advantages of small heat exchange area, small footprint, high heat exchange efficiency and long service life.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The first heat exchanger and the second heat exchanger are arranged in parallel, and the first heat exchanger and the second heat exchanger are connected in series through a heat medium pipeline. In this way, the length of the heat exchanger can be reduced, the floor space can be reduced, maintenance is facilitated, and the operation and maintenance cost of the heat exchanger can be reduced.

[0008] As a further solution of the present invention, the intermediate medium heat exchanger uses ethylene glycol aqueous solution as the heat medium. Compared with the traditional intermediate medium heat exchanger using seawater as the heat medium, ethylene glycol aqueous solution has no electrochemical corrosion, and the heat exchange tube does not need to use special pipes such as titanium steel. The skid-mounted heat exchanger using ethylene glycol aqueous solution has a longer service life and a lower cost. In addition, ethylene glycol aqueous solution has a stronger cold storage capacity and a wider range of applications, and can realize the recycling of LNG cold energy.

[0009] As a further solution of the present invention, the ethylene glycol aqueous solution flow channel in the first heat exchanger adopts a U-shaped tube, and the footprint of the first heat exchanger is reduced by increasing the number of heat medium fluid tubes. The diameter of the condenser tube in the shell of the first heat exchanger is 20mm, and the diameter of the evaporator tube is 12mm. The heat exchange tubes in the shell of the first heat exchanger are all arranged in a triangular shape.

[0010] As a further solution of the present invention, the flow channel of the 50% ethylene glycol aqueous solution in the shell of the second heat exchanger adopts a straight tube. The diameter of the heat exchange tubes in the second heat exchanger is 12 mm. The heat exchange tubes of the second heat exchanger are arranged in a triangular shape. Baffles with a circularity ratio of 30% are evenly arranged in the shell of the second heat exchanger, and the convective heat transfer coefficient of the fluid in the shell is increased by increasing the flow rate of the shell-side fluid, thereby improving the heat transfer coefficient of the second heat exchanger and reducing the exchange area.

[0011] As a further solution of the present invention, a guide plate is provided in the first heat exchanger. The guide plates in the first heat exchanger are arranged asymmetrically, with a spacing of 20 mm between the upper and lower parts, and are used to guide the vaporized intermediate medium to flow upward along the shell wall, thereby solving the problem of uneven heat exchange in traditional intermediate medium heat exchangers and enhancing heat exchange efficiency.

[0012] As a further solution of the present invention, a temperature detection unit, an intermediate medium liquid level detection unit and a control unit are provided in the first heat exchanger. The intermediate medium liquid level detection unit is arranged in the shell of the first heat exchanger, and is used to detect the intermediate medium liquid level. The control valve is arranged in the heat medium flow pipeline, and is used to adjust the flow rate of the ethylene glycol aqueous solution entering the first heat exchanger and the second heat exchanger respectively. The temperature detection unit, the intermediate medium liquid level detection unit and the control unit are electrically connected to the control valve, and the temperature detection unit adjusts the valve size and the opening angle of the valve according to the detected fluid temperature. When the liquid level detected by the intermediate medium detection unit is lower than the set liquid level, an intermediate medium replenishment signal is output.

[0013] As a further solution of the present invention, the first heat exchanger NG outlet is connected to the second heat exchanger NG inlet through a refrigerant circulation pipeline, and the first heat exchanger EG inlet is connected to the second heat exchanger EG outlet through a heat medium pipeline and an electronic three-way valve.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] First, the present invention sets two guide plates in the first heat exchanger. The guide plates are arranged asymmetrically with a spacing of 20 mm between the upper and lower plates. They are used to guide the vaporized intermediate medium to flow evenly and upward along the shell wall, solving the problem of uneven heat exchange of heat exchange tubes in traditional condensers and enhancing the heat exchange efficiency of the heat exchanger.

[0016] Secondly, the present invention uses ethylene glycol aqueous solution as heat medium, avoiding the electrochemical corrosion phenomenon caused by the traditional heat exchanger using seawater as heat medium, reducing the operation and maintenance costs of the heat exchanger, and increasing the service life of the heat exchanger. In addition, the low-temperature ethylene glycol aqueous solution can be used for cold energy recovery projects such as ice making, thereby achieving the purpose of recycling the cold energy of LNG gasification.

[0017] In addition, the present invention provides a temperature detection unit, an intermediate medium liquid level detection unit and a control unit in the first heat exchanger. The temperature detection unit, the intermediate medium liquid level detection unit and the control unit are electrically connected to the control valve, and the temperature detection unit adjusts the valve size and the opening angle of the valve according to the detected fluid temperature. When the liquid level detected by the intermediate medium detection unit is lower than the set liquid level, an intermediate medium replenishment signal is output, thereby increasing the service life of the equipment.

[0018] Finally, the gasifier of the present invention is made of stainless steel, and has the characteristics of strong corrosion resistance, small maintenance investment and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the skid-mounted heat exchanger used for LNG cold energy ice making according to the present invention.

[0020] Figure 2 The internal structure diagram of the first heat exchanger of the present invention is

[0021] Figure 3 The internal structure diagram of the second heat exchanger of the present invention is

[0022] Wherein: E1—first heat exchanger; E2—second heat exchanger; 1—baffle; 2—heat exchange tube; 3—head flange; 4—head; 5—tube shell; 6—base; 7a—natural gas (NG) inlet; 8a—NG outlet; 9a—ethylene glycol aqueous solution (EG) inlet; 10a—EG outlet; 7b—liquefied natural gas (LNG) inlet; 8b—NG outlet; 9b—EG inlet; 10b—EG outlet; 11—heat exchange warp; 12—condenser; 13—evaporator; 14—refrigerant pipeline; 15—heat medium pipeline; 18—intermediate medium flow channel; 19—guide plate; 20—condenser with a diameter of 20 mm; 21—evaporator with a diameter of 12 mm; 22—liquid intermediate heat exchange medium; 23—gas intermediate heat exchange medium; 24—outer wall of heat exchanger; 25—inner wall of second heat exchanger; 26—heat exchange tube; 27—outer wall of second heat exchanger. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1-3 As described in the background technology, the existing heat exchangers used for LNG cold energy recovery have the problems of large footprint, low heat exchange efficiency, high equipment cost, short service life, high maintenance cost, etc. In order to solve the above problems, the present application discloses a skid-mounted heat exchanger for LNG cold energy ice making.

[0025] In a typical embodiment of the present invention, Figure 1 As shown, a skid-mounted heat exchanger for LNG cold energy ice making is provided, which is composed of a first heat exchanger E1, a second heat exchanger E2, a refrigerant circulation pipeline 14, and a heat medium circulation pipeline 15. The first heat exchanger E1 and the second heat exchanger E2 are both horizontal shell and tube heat exchangers. The first heat exchanger E1 and the second heat exchanger E2 are connected in series through the heat medium pipeline 15b and the refrigerant pipeline 14, and are arranged side by side.

[0026] The first heat exchanger is provided with a shell having a liquefied natural gas (LNG) inlet 7b, a natural gas (NG) outlet 8b, an ethylene glycol aqueous solution (EG) inlet 9b, and an ethylene glycol aqueous solution (EG) outlet (10b) on the outside of the shell, and the first heat exchanger (E1) is provided with an LNG flow channel (12), an EG flow channel (13) and an intermediate medium flow channel (18) inside the shell;

[0027] The outer side of the second heat exchanger shell includes an NG inlet (7a), an NG outlet (8a), an EG inlet (9a), and an EG outlet (10a), and the second heat exchanger is provided with an NG flow channel (2) and an EG flow channel (5); the NG outlet (8b) of the first heat exchanger is connected to the inlet (7a) of the second heat exchanger NG through a refrigerant flow pipeline 14, and the inlet 9b of the first heat exchanger EG is connected to the inlet 9a of the second heat exchanger EG through a heat medium pipeline 15b;

[0028] In actual use, the intermediate medium flow channel 18 in the first heat exchanger E1 is filled with an intermediate medium, and the intermediate medium may be propylene, propane, R410a, R32, or R404.

[0029] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A skid-mounted heat exchanger for LNG cold energy ice making, characterized by: It comprises a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is provided with a liquefied natural gas inlet, a low-temperature natural gas outlet, a 50% ethylene glycol aqueous solution inlet, and a 50% ethylene glycol aqueous solution outlet on the outside, and the inlet and outlet of the heated substance and the cooling substance should be arranged correspondingly up and down or left and right; the first heat exchanger is provided with a liquefied natural gas flow channel and a 50% ethylene glycol aqueous solution flow channel inside; the intermediate medium exchanges heat between the liquefied natural gas flow channel and the 50% ethylene glycol aqueous solution flow channel; the liquefied natural gas flow channel and the 50% ethylene glycol aqueous solution flow channel inside the first heat exchanger are both U-shaped tubes; The second heat exchanger is provided with a low-temperature natural gas inlet, a low-temperature natural gas outlet, a 50% ethylene glycol aqueous solution inlet, and a 50% ethylene glycol aqueous solution outlet on the outside. The second heat exchanger shell is provided with a low-temperature natural gas flow channel and a 50% ethylene glycol aqueous solution flow channel on the inside; 50% ethylene glycol aqueous solution, the ethylene glycol aqueous solution inlet of the first heat exchanger is connected to the ethylene glycol aqueous solution outlet of the second heat exchanger through a heat medium circulation pipeline; NG inlet, the first heat exchanger NG outlet is connected with the second heat exchanger NG outlet via a refrigerant pipeline; It also includes a temperature detection unit, an intermediate medium liquid level detection unit and a control valve. The temperature detection unit is arranged at the LNG inlet, NG outlet, ethylene glycol aqueous solution inlet, and ethylene glycol aqueous solution outlet of the first heat exchanger, and the NG inlet, NG outlet, ethylene glycol aqueous solution inlet, and ethylene glycol aqueous solution outlet of the second heat exchanger, and is used to detect the inlet and outlet temperatures of NG and ethylene glycol aqueous solution; The intermediate medium liquid level detection unit is arranged in the first heat exchanger shell and is used to detect the intermediate medium liquid level; The control valve is arranged on the heat medium circulation pipeline, and is used to adjust the flow rate of the 50% ethylene glycol aqueous solution entering the first heat exchanger and the second heat exchanger respectively; The temperature detection unit, the intermediate medium liquid level detection unit, the control unit and the control valve are electrically connected. The temperature detection unit adjusts the valve size and the opening angle of the valve according to the detected fluid temperature. When the liquid level detected by the intermediate medium detection unit is lower than the set liquid level, an intermediate medium replenishment signal is output.

2. The skid-mounted heat exchanger according to claim 1, characterized in that The LNG inlet, the NG outlet, the ethylene glycol aqueous solution inlet, and the ethylene glycol aqueous solution outlet of the first heat exchanger are all on one side of the first heat exchanger.

3. The skid-mounted heat exchanger according to claim 2, characterized in that The NG inlet and the NG outlet of the second heat exchanger are located on both sides of the NG flow channel.

4. The skid-mounted heat exchanger according to claim 3, characterized in that The ethylene glycol inlet and the ethylene glycol aqueous solution outlet of the second heat exchanger are located on both sides of the EG flow channel.

5. The skid-mounted heat exchanger according to claim 4, characterized in that The ratio of the shell diameter to the tube length of the second heat exchanger is set to be greater than 4 and less than 14.

6. The skid-mounted heat exchanger according to claim 5, characterized in that The diameter of the condensing tube of the first heat exchanger is 20 mm, the diameter of the evaporating tube is 12 mm, and the heat exchange tubes of the first heat exchanger are arranged in a triangle.

7. The skid-mounted heat exchanger according to claim 6, characterized in that Two guide plates are arranged in the first heat exchanger, and the guide plates are arranged asymmetrically with a height spacing of 20 mm.

8. The skid-mounted heat exchanger according to claim 7, characterized in that The diameter of the heat exchange tube of the second heat exchanger is 12 mm, and the heat exchange tube of the second heat exchanger is arranged in a triangle.

9. The skid-mounted heat exchanger according to claim 8, characterized in that The pipe box flange of the first heat exchanger is arranged on one side of the first heat exchanger. The pipe box flange of the second heat exchanger is arranged on both sides of the NG flow channel.

Images