Steam generating heater

Abstract

This invention proposes a steam heating element, comprising a shell, a coil disposed within the shell, and a heating element. The heating element is located within the space where the coil rotates. One end of the coil is a water inlet, and the other end is a steam outlet. The heating element heats the coil, causing the liquid water inside to vaporize and generate steam. The diameter of the liquid water section at the front of the coil is larger than the diameter of the steam section at the rear of the coil; and / or the gap between the outer walls of the tubes in the steam section at the rear of the coil is larger than the gap between the outer walls of the tubes in the liquid water section at the front of the coil. This invention achieves high-efficiency heat exchange and low flow resistance at high power density in the liquid water section at the front of the coil through a combination of "large diameter + small pitch," thus improving heat absorption efficiency. In the steam section at the rear of the coil, a combination of "small diameter + even smaller pitch" creates a large heat exchange surface area per unit length, increasing the heat dissipation rate, significantly alleviating overheating problems caused by poor heat dissipation in the rear section of the coil, and extending its service life.

Description

Technical Field

[0001] This utility model belongs to the field of electric heating device technology, specifically relating to a steam heating element. Background Technology

[0002] A steam heating element is a device that uses heat energy to rapidly vaporize water. It is widely used in agricultural production, medical disinfection, pharmaceuticals, chemicals, material maintenance (such as tea fermentation, component maintenance, and cable steaming), and reactor equipment. As a new type of equipment to replace traditional boilers, it has significant advantages in terms of automation, high efficiency, energy saving, and environmental protection.

[0003] Steam heating elements vaporize liquid water inside a heating coil to produce steam. Their core structure typically includes a coil, a heating element, and inlet / outlet ports. In existing technologies, the coils often employ a design with evenly spaced distribution and uniform diameter (e.g., patents CN206247302U, CN117985655A). While this structure is simple, it suffers from significant thermodynamic imbalances during actual operation, leading to low heating efficiency, localized overheating, and shortened lifespan. Specific manifestations are as follows:

[0004] 1) Insufficient heating in the front section (liquid water zone) of the coil, and overheating in the rear section (steam zone). The water near the coil inlet is low-temperature liquid water with a high specific heat capacity, requiring a large amount of heat to reach its boiling point. If the heat flux provided by the heating element is insufficient (e.g., uniform power distribution of the heating wire), this section will heat up slowly, reducing steam generation efficiency. Once the liquid water is completely vaporized, the convective heat transfer coefficient between the steam and the coil wall is significantly lower than that of the liquid water (due to the poor thermal conductivity of steam). Heat cannot be effectively transferred to the medium (e.g., air), leading to an abnormally high temperature on the rear section of the coil wall. Insufficient heating in the front section and heat accumulation in the rear section create a "thermal imbalance," resulting in decreased overall thermal efficiency. Long-term operation can easily lead to material oxidation, creep, or even burnout.

[0005] 2) The coil has a consistent diameter throughout and is arranged in a uniform spiral. The contact area between the heating element and each section of the coil is the same. However, the difference in heat absorption capacity between liquid water and steam is not taken into account, resulting in unreasonable energy distribution and significantly reducing service life. Utility Model Content

[0006] To address the technical problems existing in the prior art, the first aspect of this utility model is to provide a steam heating element.

[0007] In this embodiment of the invention, a steam heating element includes a shell, a coil disposed within the shell, and a heating element. The heating element is located within the space where the coil rotates. One end of the coil is a water inlet, and the other end is a steam outlet. The heating element is used to heat the coil, causing the liquid water inside to vaporize and generate steam. The diameter of the liquid water section in the front part of the coil is larger than the diameter of the steam section in the rear part of the coil. And / or the gap between the outer walls of the steam section in the rear part of the coil is larger than the gap between the outer walls of the liquid water section in the front part of the coil.

[0008] Compared with the prior art, the beneficial effects of the superior technical solution of this utility model include:

[0009] 1. The liquid water zone at the front of the coil achieves high-efficiency heat exchange (utilizing the high heat transfer coefficient of water) and low flow resistance under high power density through the combination of "large pipe diameter + small pitch", thereby improving heat absorption efficiency. The steam zone at the rear of the coil creates a huge heat exchange surface area per unit length through the combination of "small pipe diameter + even smaller pitch", increasing the heat removal rate, reducing the pipe wall temperature required to achieve thermal equilibrium, significantly alleviating the overheating problem caused by poor heat dissipation at the rear of the coil, and extending its service life.

[0010] 2. The heating element adopts three-phase wiring, which utilizes the natural current balance characteristics of three-phase power supply to effectively reduce single-phase current and line load, alleviate the line heating problem from the root, improve safety and reduce cable costs; moreover, three-phase power supply provides more flexible and stable power output, laying the foundation for precise temperature control.

[0011] 3. The power of the heating element decreases gradually from the water inlet to the air outlet. The high power in the front section of the heating element quickly raises the water temperature to the boiling point, while the low power in the back section avoids overheating of the steam zone and improves the overall thermal efficiency. Moreover, the low power in the back section can reduce ineffective heating in the steam zone and reduce energy consumption. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of a steam heating element in one embodiment.

[0013] The reference numerals in the accompanying drawings include: outer casing 1, coil 2, water inlet 2a, air outlet 2b, front section of coil 21, rear section of coil 22, heating element 3, first heating wire 31, second heating wire 32, third heating wire 33, first lead wire connector 34, second lead wire connector 35, and third lead wire connector 36. Detailed Implementation

[0014] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0015] This embodiment provides a steam heating element, such as... Figure 1 As shown, it includes a housing 1, a coil 2 disposed in the housing 1, and a heating element 3. The heating element 3 is inserted into the space where the coil 2 is coiled. One end of the coil 2 is a water inlet 2a, and the other end of the coil 2 is an air outlet 2b. For example, the housing 1 is arranged horizontally, the water inlet 2a is located on the left side of the housing 1, and the air outlet 2b is located on the right side of the housing 1. The heating element 3 is used to heat the coil 2 so that the liquid water inside it vaporizes to produce water vapor.

[0016] In a preferred embodiment, the diameter of the liquid water section 21 of the coil is larger than the diameter of the steam section 22 of the coil; the helical pitch of the liquid water section 21 of the coil is larger than the helical pitch of the steam section 22 of the coil; and the gap between the outer walls of the steam section 22 of the coil is larger than the gap between the outer walls of the liquid water section 21 of the coil.

[0017] In one embodiment of this utility model, the diameter of the liquid water section 21 of the coil is 1.5-2.5 times, for example, 2 times, the diameter of the steam section 22 of the coil. The gap between the outer walls of the pipes in the steam section 22 of the coil is 1.5-2 times the gap between the outer walls of the pipes in the liquid water section 21 of the coil, for example, the gap between the outer walls of the pipes in the liquid water section 21 of the coil is 0.5-1.5 mm, and the gap between the outer walls of the pipes in the steam section 22 of the coil is 1-2 mm.

[0018] Specifically, the pipe diameter of the liquid water section 21 in the front section of the coil is 7mm, and the spiral pitch of the liquid water section 21 in the front section of the coil is 8mm, so the gap between the outer walls of the pipes in the liquid water section 21 in the front section of the coil is 1mm. The pipe diameter of the steam section 22 in the rear section of the coil is 3.5mm, and the spiral pitch of the steam section 22 in the rear section of the coil is 5mm, so the gap between the outer walls of the pipes in the steam section 22 in the rear section of the coil is 1.5mm.

[0019] In this invention, the coil 2 is made of stainless steel, such as 316L stainless steel or a nickel-based alloy. It maintains stability even under high-temperature conditions in the steam zone, preventing oxide scale from detaching and contaminating the water vapor. It also exhibits excellent creep resistance, making it less prone to deformation and cracking during long-term thermal cycling. The outer shell can be made of materials that are high-temperature resistant, corrosion-resistant, have high mechanical strength, and are electrically safe, such as 316L stainless steel (with a nano-ceramic coating on the inner wall), aluminum alloy, titanium alloy, flame-retardant PPS plastic, PEEK plastic, or carbon fiber composite material.

[0020] The steam heating element of this invention uses a φ7mm stainless steel tube in the liquid water zone of the coil front section 21. The larger tube diameter provides a larger internal flow cross-sectional area and external heat exchange surface area, improving heat absorption efficiency. Simultaneously, it employs a tight spiral winding with an 8mm small spiral pitch, resulting in extremely small gaps (approximately 1mm) between the outer walls of the tube, forming a highly dense heat exchange area. This combination of "large tube diameter + small pitch (8mm)" achieves an extremely high effective heating surface area per unit axial length. The aim is to efficiently and rapidly transfer a large amount of heat energy to the liquid water, significantly shortening the time required for the liquid water to reach saturation temperature, thus solving the core problem of low water temperature and slow heating at the inlet 2a. At the same time, the larger tube diameter helps maintain smooth flow of liquid water in the coil front section 21, reducing the flow resistance of the liquid water.

[0021] The steam zone of the rear section 22 of the coil uses φ3.5mm stainless steel tubes with a more compact 5mm pitch spiral winding. The gap between the outer walls of the tubes is 1.5mm, forming a highly compact heat exchange structure. This combination of "small tube diameter + smaller pitch (5mm)" creates a huge heat exchange surface area per unit length. At the same time, increasing the gap between the outer walls of the tubes directly aims to increase the heat dissipation rate, thereby reducing the tube wall temperature required to achieve thermal equilibrium. This significantly alleviates the overheating problem caused by poor heat dissipation in the rear section of the coil 2 and extends its service life.

[0022] like Figure 1 As shown, in another preferred embodiment of this utility model, the heating element 3 includes at least one U-shaped heating wire, which extends along the length of the outer shell. Specifically, the opening of the U-shaped heating wire can be as follows: Figure 1 The side near the air outlet 2a can also be near the water inlet 2a.

[0023] More preferably, the heating element 3 is a three-phase power supply heating structure. The heating element 3 includes three U-shaped heating wires and three lead wire connectors. The three heating wires are the first heating wire 31, the second heating wire 32 and the third heating wire 33, and the three lead wire connectors are the first lead wire connector 34, the second lead wire connector 35 and the third lead wire connector 36.

[0024] The first lead connector 34 is electrically connected to the first end of the first heating wire 31 and the first end of the second heating wire 32. The second lead connector 35 is electrically connected to the second end of the first heating wire 31 and the second end of the third heating wire 33. The third lead connector 36 is electrically connected to the first end of the third heating wire 33 and the second end of the second heating wire 32. This allows electrical energy to be supplied to the starting ends of the first heating wire 31 and the second heating wire 32 through the first lead connector 34, to the ends of the first heating wire 31 and the third heating wire 33 through the second lead connector 35, and to the ends of the second heating wire 32 and the starting end of the third heating wire 33 through the third lead connector 36.

[0025] The heating element 3 is powered by three-phase AC (380V). The three lead connectors connected to the three heating wires can be connected to a three-phase socket (380V AC) using a star (Y-type) or delta (Δ-type) connection (the specific circuit connection method is existing technology and will not be detailed here), ensuring balanced three-phase load, avoiding overload of any one phase, and improving energy utilization. Furthermore, the heating element 3 has three heating wires. If one heating wire is damaged (e.g., open circuit), the remaining two can still maintain heating function (power reduced but not completely failed), improving the equipment's fault tolerance. Moreover, compared to a single heating wire structure, the parallel operation of three heating wires reduces the operating current of a single heating wire, reduces heat loss, and extends service life.

[0026] In another preferred embodiment, three U-shaped heating wires are located on the same plane and nested together. For example, the first heating wire 31 is located in the outermost layer, the second heating wire 32 is embedded inside the first heating wire 31 in the middle layer, and the third heating wire 33 is embedded inside the second heating wire 32 in the innermost layer. This makes the heating body 3 a flat structure, and the outer shell 1 and the coil 2 can be set as cylindrical or flat rectangles according to the actual situation.

[0027] In another preferred embodiment, the heating element 3 employs a non-uniform power distribution, with the heating power near the water inlet 2a being higher than that near the air outlet 2b, resulting in a higher power output at the front end of the heating element 3 compared to the rear end. The high power at the front end of the heating element 3 rapidly raises the water temperature to the boiling point, while the low power at the rear end prevents overheating in the steam zone, thus improving overall thermal efficiency. Furthermore, the low power at the rear end reduces ineffective heating in the steam zone, lowering energy consumption.

[0028] More preferably, the heating element 3 is a heating wire, whose resistivity gradually decreases along the direction from the water inlet 2a to the air outlet 2b, achieving high power at the front and low power at the back. No complex control system is needed; the power gradient distribution is automatically achieved through the material's resistivity characteristics, resulting in a simple and reliable structure. Moreover, compared to independent temperature control solutions, it reduces circuit design and manufacturing costs.

[0029] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A steam heating element, comprising a shell, a coil disposed within the shell, and a heating element, wherein the heating element is located within the space where the coil rotates, one end of the coil is a water inlet, and the other end of the coil is a steam outlet, and the heating element is used to heat the coil to vaporize the liquid water inside to generate steam; characterized in that: The diameter of the liquid water section in the front part of the coil is larger than the diameter of the steam section in the rear part of the coil, and the diameter of the liquid water section in the front part of the coil is 1.5-2.5 times the diameter of the steam section in the rear part of the coil. And / or the helical pitch of the liquid water section in the front section of the coil is greater than the helical pitch of the steam section in the rear section of the coil, and the gap between the outer walls of the pipes in the steam section in the rear section of the coil is greater than the gap between the outer walls of the pipes in the liquid water section in the front section of the coil.

2. The steam generating body according to claim 1, wherein The gap between the outer walls of the pipes in the steam zone of the coil section is 1.5-2 times the gap between the outer walls of the pipes in the liquid water zone of the coil section.

3. The steam generating body according to claim 2, wherein The gap between the outer walls of the pipes in the liquid water zone at the front of the coil is 0.5-1.5 mm, and the gap between the outer walls of the pipes in the steam zone at the rear of the coil is 1-2 mm.

4. The steam generating body according to claim 1, wherein The diameter of the liquid water section in the front part of the coil is 7 mm, and the diameter of the steam section in the rear part of the coil is 3.5 mm.

5. The steam generating body according to claim 4, wherein The spiral spacing of the liquid water zone at the front of the coil is 8mm, and the spiral spacing of the steam zone at the rear of the coil is 5mm.

6. The steam generating body according to claim 1, wherein The heating element includes at least one U-shaped heating wire that extends along the length of the outer shell.

7. The steam generating body according to claim 6, wherein The heating element is a three-phase power supply heating structure. The heating element includes three U-shaped heating wires and three lead wire connectors. The three heating wires are the first heating wire, the second heating wire, and the third heating wire. The three lead wire connectors are the first lead wire connector, the second lead wire connector, and the third lead wire connector. The first lead connector is electrically connected to both the first end of the first heating wire and the first end of the second heating wire. The second lead connector is electrically connected to both the second end of the first heating wire and the second end of the third heating wire. The third lead connector is electrically connected to both the first end of the third heating wire and the second end of the second heating wire.

8. The steam generating body according to claim 1, wherein The heating element is an electric heating wire, whose resistivity decreases gradually from the water inlet to the air outlet.

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