A skid-mounted heat exchanger for LNG cold energy ice making

Abstract

The application discloses a skid-mounted heat exchanger for ice making by LNG cold energy, which comprises a first heat exchanger, a second heat exchanger, a cold medium flow pipeline and a hot medium flow 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; the inner side of the first heat exchanger shell is provided with an LNG flow channel, an EG flow channel and an intermediate medium flow channel; the outer side of the second heat exchanger shell comprises an NG inlet, an NG outlet, an EG inlet and an EG outlet; the second heat exchanger is provided with an NG flow channel and an EG flow channel; the NG outlet of the first heat exchanger is connected with the NG inlet of the second heat exchanger through the cold medium flow pipeline; the EG inlet of the first heat exchanger is connected with the EG inlet of the second heat exchanger through the hot medium pipeline; the first heat exchanger and the second heat exchanger are both of a tube-shell heat exchanger structure. The gasifier has the characteristics of strong corrosion resistance, small maintenance investment and long service life.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, specifically a skid-mounted heat exchanger for LNG cold energy ice making. Background Technology

[0002] In recent years, natural gas has played an increasingly important role in global energy due to its advantages such as high efficiency, cleanliness, economy, and safety. Liquefied natural gas (LNG), with its ease of storage and transportation, flexibility, and efficiency, has seen its share in my country's natural gas supply increase year by year, becoming a crucial component in ensuring my country's natural gas supply. Before use, LNG needs to be vaporized into a gas at room temperature. Traditional LNG vaporization stations release the cold energy of LNG into the surrounding environment through ambient air vaporizers or water bath vaporizers, which not only wastes energy but also causes cold pollution to the local environment. Therefore, the utilization of LNG's cold energy is now essential.

[0003] LNG cryogenic heat transfer equipment is the core equipment for ensuring LNG vaporization and simultaneously recovering LNG cold energy. Currently, there are three main types of equipment under development for LNG cold energy heat exchange: open-frame vaporizers (ORV), water bath vaporizers (SCV), and intermediate medium heat exchangers (IFV). Intermediate medium heat exchangers are widely used due to their advantages such as resistance to freezing and blockage, high heat exchange efficiency, and ease of control.

[0004] Traditional intermediate medium heat exchangers typically consist of an evaporator, a condenser, and a thermostat, 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 within the evaporator are all straight sections, resulting in a large footprint, large heat exchange area, and high equipment cost. Traditional intermediate medium heat exchangers lack internal baffles, leading to uneven heat exchange in the condenser tubes. Furthermore, when installed under turbulent conditions such as marine environments, traditional intermediate medium heat exchangers may experience "dry burning" of the evaporator heat exchange tubes and wetting of the condenser heat exchange tubes, affecting the heat exchange efficiency of both parts. Traditional intermediate medium heat exchangers use seawater as the heat medium to transfer cold energy to the surrounding environment, failing to achieve the effect of LNG cold energy recovery and utilization, resulting in significant energy waste. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a skid-mounted heat exchanger for LNG cold energy ice making, which is used to recover and utilize the large amount of cold energy released during LNG vaporization. It has advantages such as small heat exchange area, small footprint, high heat exchange efficiency, and long service life.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] The first and second heat exchangers are arranged in parallel, and connected in series via a heat medium pipeline. This reduces the length of the heat exchangers, decreases the floor space required, facilitates maintenance, and lowers operating and maintenance costs.

[0008] As a further aspect of the present invention, the intermediate medium heat exchanger uses an ethylene glycol aqueous solution as the heat medium. Compared to traditional intermediate medium heat exchangers that use seawater as the heat medium, the ethylene glycol aqueous solution has no electrochemical corrosiveness, and the heat exchange tubes do not require special materials such as titanium steel. Skid-mounted heat exchangers using ethylene glycol aqueous solutions have a longer service life and are cheaper to manufacture. Furthermore, ethylene glycol aqueous solutions have stronger cold storage capacity, a wider range of applications, and can realize the recovery and utilization of LNG cold energy.

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

[0010] As a further aspect of the present invention, the 50% ethylene glycol aqueous solution flow channel inside the shell of the second heat exchanger is a straight pipe. The diameter of all 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 pattern. Baffles with a 30% segment radius are uniformly arranged inside the shell of the second heat exchanger. By increasing the flow path of the fluid in the shell, the convective heat transfer coefficient of the fluid inside the shell is improved, thereby increasing the heat transfer coefficient of the second heat exchanger and reducing the heat exchange area.

[0011] As a further aspect of the present invention, the first heat exchanger is provided with a guide plate. The guide plate inside the first heat exchanger is arranged asymmetrically with a vertical spacing of 20mm, which is 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 aspect of the present invention, the first heat exchanger is provided with a temperature detection unit, an intermediate medium level detection unit, and a control unit. The intermediate medium level detection unit is disposed within the shell of the first heat exchanger and is used to detect the intermediate medium level. The control valve is disposed in the heat medium pipeline and is used to regulate 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 level detection unit, and the control unit are electrically connected to the control valve. The temperature detection unit adjusts the opening angle of the valve according to the detected fluid temperature. When the intermediate medium level detected by the intermediate medium detection unit is lower than a set level, it outputs an intermediate medium replenishment signal.

[0013] As a further embodiment of the present invention, the outlet of the first heat exchanger NG and the inlet of the second heat exchanger NG are connected by a refrigerant pipeline, and the inlet of the first heat exchanger EG and the outlet of the second heat exchanger EG are connected by 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, this invention incorporates two guide vanes within the first heat exchanger. These vanes are arranged asymmetrically with a vertical spacing of 20mm. This guide vanes guide the vaporized intermediate medium to flow evenly upwards along the shell wall, solving the problem of uneven heat exchange in traditional condensers and enhancing the heat exchanger's efficiency.

[0016] Secondly, this invention uses an ethylene glycol aqueous solution as the heat medium, avoiding the electrochemical corrosion that occurs in traditional heat exchangers using seawater as the heat medium, thus reducing the operating and maintenance costs of the heat exchanger and extending its service life. Furthermore, the low-temperature ethylene glycol aqueous solution can be used in cold energy recovery projects such as ice making, thereby achieving the goal of recovering and utilizing the cold energy from LNG vaporization.

[0017] Furthermore, the present invention includes a temperature detection unit, an intermediate medium level detection unit, and a control unit within the first heat exchanger. These units are electrically connected to a control valve. The temperature detection unit adjusts the valve's opening angle based on the detected fluid temperature. When the intermediate medium level detected by the intermediate medium detection unit is lower than a set level, it outputs an intermediate medium replenishment signal, thereby improving the equipment's service life.

[0018] Finally, the vaporizer of this invention is made of stainless steel, which has the characteristics of strong corrosion resistance, low maintenance investment, and long service life. Attached Figure Description

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

[0020] Figure 2 This is a diagram showing the internal structure of the first heat exchanger of the present invention.

[0021] Figure 3 This is a diagram showing the internal structure of the second heat exchanger of the present invention.

[0022] Wherein: E1—First heat exchanger; E2—Second heat exchanger; 1—Baffle plate; 2—Heat exchange tube; 3—End flange; 4—End; 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 tube; 12—Condenser tube; 13—Evaporator tube; 14—Refrigerator pipeline; 15—Heat medium pipeline; 18—Intermediate medium flow channel; 19—Guide plate; 20—Condenser tube with a diameter of 20mm; 21—Evaporator tube with a diameter of 12mm; 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 Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1-3 As described in the background section, existing heat exchangers for LNG cold energy recovery have problems such as large footprint, low heat exchange efficiency, high equipment cost, short service life, and high maintenance cost. In order to solve the above problems, this application proposes a skid-mounted heat exchanger for LNG cold energy ice making.

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

[0026] The first heat exchanger has a shell on its outer side, which includes an LNG inlet 7b, an NG outlet 8b, an EG inlet 9b, and an EG outlet 10b. The shell of the first heat exchanger E1 has an LNG flow channel 12, an EG flow channel 13, and an intermediate medium flow channel 18.

[0027] The outer side of the shell of the second heat exchanger includes an NG inlet 7a, an NG outlet 8a, an EG inlet 9a, and an EG outlet 10a. 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 NG inlet 7a of the second heat exchanger through a refrigerant pipe 14. The EG inlet 9b of the first heat exchanger is connected to the EG inlet 9a of the second heat exchanger through a heat medium pipe 15.

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

[0029] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

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

Claims

1. A skid-mounted heat exchanger for LNG cold energy ice making, characterized in that: The system includes a first heat exchanger and a second heat exchanger. The first heat exchanger has an external liquefied natural gas (LNG) inlet, a cryogenic natural gas outlet, a 50% ethylene glycol aqueous solution inlet, and a 50% ethylene glycol aqueous solution outlet. The inlets and outlets of the heated and cooled substances should be arranged vertically or horizontally. The first heat exchanger has an LNG flow channel and a 50% ethylene glycol aqueous solution flow channel on its internal side. The intermediate medium exchanges heat between the LNG flow channel and the 50% ethylene glycol aqueous solution flow channel. Both the LNG flow channel and the 50% ethylene glycol aqueous solution flow channel inside the first heat exchanger are U-shaped tubes. The second heat exchanger has 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 its outer side; the second heat exchanger shell has a low-temperature natural gas flow channel and a 50% ethylene glycol aqueous solution flow channel on its inner side. The inlet of the first heat exchanger and the outlet of the second heat exchanger are connected by a heat medium pipeline; The natural gas outlet of the first heat exchanger is connected to the natural gas inlet of the second heat exchanger via a refrigerant pipeline; It also includes a temperature detection unit, an intermediate medium level detection unit, and control valves. The temperature detection unit is installed at the liquefied natural gas inlet, natural gas outlet, ethylene glycol aqueous solution inlet, and ethylene glycol aqueous solution outlet of the first heat exchanger, and at the natural gas inlet, natural gas outlet, ethylene glycol aqueous solution inlet, and ethylene glycol aqueous solution outlet of the second heat exchanger, for detecting the inlet and outlet temperatures of natural gas and ethylene glycol aqueous solution. The intermediate medium level detection unit is configured inside the first heat exchanger shell and is used to detect the intermediate medium level. The control valves are configured in the heat medium pipeline and are used to regulate 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, intermediate medium level detection unit, control unit, and control valve are electrically connected. The temperature detection unit adjusts the opening angle of the valve according to the detected fluid temperature. When the intermediate medium detection unit detects that the liquid level is lower than the set liquid level, it outputs an intermediate medium replenishment signal.

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

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

4. The skid-mounted heat exchanger according to claim 3, characterized in that, The ethylene glycol inlet and ethylene glycol aqueous solution outlet of the second heat exchanger are located on both sides of the ethylene glycol aqueous solution 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 between 4 and 14.

6. The skid-mounted heat exchanger according to claim 5, characterized in that, The condenser tube of the first heat exchanger has a diameter of 20 mm, the evaporator tube has a diameter of 12 mm, and the heat exchange tubes of the first heat exchanger are arranged in a triangular pattern.

7. The skid-mounted heat exchanger according to claim 6, characterized in that, The first heat exchanger is equipped with two guide vanes, which are arranged asymmetrically with a height spacing of 20mm.

8. The skid-mounted heat exchanger according to claim 7, characterized in that, The heat exchange tubes of the second heat exchanger have a diameter of 12 mm and are arranged in a triangular pattern.

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

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