PTC heater for flow battery

Abstract

The present invention discloses a PTC heater for a flow battery, comprising an inner tube, an outer tube and a PTC heating group, wherein the inner tube is made of an insulating, corrosion-resistant and high thermal conductivity material, the outer tube is arranged outside the inner tube, a gap is arranged between the outer tube and the inner tube, the PTC heating group is arranged in the gap, a first flange connected to the outer tube is arranged at both ends, a non-metallic support seat is arranged at both ends of the outer tube, the inner tube passes through the support seat, a non-metallic second flange is arranged at one end of the support seat away from the outer tube, the center of the second flange has a through hole, the end of the through hole facing the outer tube is a stepped hole, the inner tube extends into the stepped hole, and a gap is arranged between the two end edges of the inner tube and the end of the stepped hole away from the inner tube. Compared with the prior art, the invention realizes strong alkali corrosion resistance and improved thermal conductivity, thereby preventing the electrolyte from directly contacting the PTC heating group and improving safety; the outer tube is arranged outside the inner tube to improve the overall impact resistance.

Description

Technical Field

[0001] The invention relates to a PTC heater, in particular to a PTC heater for a liquid flow battery. Background Art

[0002] The electrolyte in the liquid flow battery of the energy storage system is a strong alkali with a pH value greater than 14. During the electrochemical reaction, it needs to be maintained between 45-50°C to ensure the normal operation of the system. Therefore, precise control of the heating, temperature control and insulation of the electrolyte is particularly important.

[0003] The existing technology is that the electric heating tube is wrapped with a 1mm thick Teflon sleeve to form a heating part immersed in the electrolyte to solve the problem of the electric heating tube's resistance to strong alkali corrosion. A thermistor (NTC) is built in between the electric heating tube and the Teflon sleeve, and the heating and temperature control are carried out through the main circuit control.

[0004] Problems encountered during use:

[0005] 1. After the electric heating tube is started, the temperature rises quickly, with the highest temperature being 600-700℃. The electric heating tube is a constant resistance, and the power is stable under the same voltage. The temperature will continue to rise. It is necessary to feedback the temperature to the main circuit through NTC, and continuously adjust the voltage or disconnect the circuit to control the temperature. High temperature will damage the structure of the Teflon sleeve in the electrolyte, resulting in leakage. At the same time, excessive temperature will cause irreversible damage to the NTC, affecting its accuracy and stability. Continuous high temperature after NTC failure will bring great safety hazards to the liquid flow system. In addition, the electric heating tube has a short service life, and frequent failure and replacement will bring high maintenance costs.

[0006] 2. Teflon has poor thermal conductivity, and its thermal conductivity coefficient is not higher than 0.3W / (m·K), so the wall thickness needs to be thinner. However, thinner-walled casings are easily damaged during production and use, which may cause battery leakage and pose a great safety hazard.

[0007] 3. The heating method of this product is to directly immerse it in the electrolyte for heating. When the NTC fails, the electric heating tube will be continuously heated, which will eventually cause the electrolyte temperature to be too high and accelerate the chemical reaction inside the battery, causing damage and failure of the internal structure of the battery, thereby shortening the battery life. Summary of the invention

[0008] The purpose of the present invention is to provide a PTC heater for a liquid flow battery, and the technical problem to be solved is to improve the heating efficiency and safety.

[0009] To solve the above problems, the present invention adopts the following technical solutions: a PTC heater for a liquid flow battery, comprising an inner tube, an outer tube and a PTC heating group, the inner tube being made of an insulating, corrosion-resistant and high thermal conductivity material, the outer tube being arranged outside the inner tube, a gap being arranged between the outer tube and the inner tube, the PTC heating group being arranged in the gap, first flanges connected to the outer tube being arranged at both ends, non-metallic support seats being arranged at both ends of the outer tube, the support seats being abutted against the first flanges, the inner tube passing through the support seats, a non-metallic second flange being arranged at one end of the support seat away from the outer tube, the second flange being connected and fixed to the support seat and the first flange by a bolt assembly, a through hole being provided in the center of the second flange, the end of the through hole facing the outer tube being a stepped hole, the inner tube extending into the stepped hole, the inner tube and the stepped hole being sealed by a corrosion-resistant and waterproof first sealing ring, and gaps being provided between the edges of both ends of the inner tube and the end of the stepped hole away from the inner tube.

[0010] Furthermore, the inner tube is made of ceramic material.

[0011] Furthermore, the inner tube is made of silicon carbide material.

[0012] Furthermore, a corrosion-resistant and waterproof second sealing ring is provided between the support seat and the second flange.

[0013] Furthermore, a corrosion-resistant and waterproof rubber pad is provided between the first flange and the support seat.

[0014] Furthermore, one of the support seats is provided with a through hole for the cable of the PTC heating group to extend out, and waterproof silicone is provided between the through hole and the cable.

[0015] Furthermore, the outer tube is wrapped with a thermal insulation layer.

[0016] Furthermore, a heat shrink tubing is provided outside the thermal insulation layer.

[0017] Compared with the prior art, the present invention realizes resistance to strong alkali corrosion and improved thermal conductivity by making the inner tube for the electrolyte of the flow battery flow out of an insulating, corrosion-resistant and highly thermally conductive material, and arranges the PTC heating group outside the inner tube so that the electrolyte enters the heating space formed by the PTC heating group for heating, thereby improving safety. Since the PTC heating group and the electrolyte are isolated and heated by the insulating, corrosion-resistant and highly thermally conductive inner tube, direct contact between the electrolyte and the PTC heating group is prevented, thereby improving safety. An outer tube is arranged outside the inner tube to improve the overall impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a perspective view of the present invention.

[0019] Figure 2 It is a schematic diagram of the internal structure of the present invention.

[0020] Figure 3 It is a schematic diagram of the connection between flanges of the present invention.

[0021] Figure 4 yes Figure 2 A partial enlarged view of .

[0022] Figure 5 It is an exploded schematic diagram of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figures 1 to 5 As shown, the present invention discloses a PTC heater for a flow battery, which mainly includes:

[0025] An inner tube 3, the inner tube 3 is made of an insulating, corrosion-resistant and high thermal conductivity material, the inner tube 3 is used to allow the electrolyte to flow through the inner tube 3, and the inner tube 3 is made of a ceramic material;

[0026] The outer tube 5 is arranged outside the inner tube 3, and the outer tube 5 and the inner tube 3 are coaxially arranged, and a gap is provided between the outer tube 5 and the inner tube 3; the outer tube 5 is used to improve the impact resistance of the product, and at the same time protect the inner tube 3 from external impact; the outer tube 5 is made of stainless steel, preferably 304 stainless steel.

[0027] The PTC heating group 13 is arranged in the gap. The PTC heating group 13 includes a plurality of PTC heating cores, which surround the inner tube 3. The PTC heating cores extend along the axis of the inner tube 3. The electric heating tube is changed into a PTC heating group. A PTC low-temperature sheet with a working temperature not higher than 200°C is selected. Since the PTC heating core has a self-limiting temperature characteristic, the maximum core temperature does not exceed 200°C. When the liquid is 45°C at a flow rate of 300L / min, the surface temperature of the inner tube 3 does not exceed 50°C, which can meet the heating requirement of 45-50°C for the electrolyte.

[0028] like Figures 1 to 3As shown, first flanges 4 connected thereto are welded at both ends of the outer tube 5, a first flange through hole is provided on the first flange 4, the first flange 4 is made of the same material as the outer tube 5, and non-metallic support seats 9 are provided at both ends of the outer tube 5, respectively, which are waterproof and insulated while protecting the internal wires, the support seat 9 is annular, and an extended edge 16 is provided at the end opposite to the first flange 4, the edge 16 is against the first flange 4, a support seat through hole opposite to the position of the first flange through hole is provided on the edge 16, a corrosion-resistant and waterproof rubber pad 10 is provided between the edge 16 and the first flange 4, the rubber pad 10 is made of ethylene propylene diene monomer (EPDM) rubber or silicone rubber, the inner tube 3 passes through the support seat 9, and a non-metallic second flange 8 is provided at the end of the support seat 9 away from the outer tube 5, in addition to the second flange through hole opposite to the support seat through hole, the second flange 8 , and a pipeline connection hole for connecting to the liquid flow battery pipeline is provided; the second flange 8 is connected and fixed to the support seat 9 and the first flange 4 by a bolt assembly 14, and the center of the second flange 8 has a through hole, and the end of the through hole facing the outer tube 5 is a stepped hole 18, and the inner tube 3 extends into the stepped hole 18. The inner tube 3 and the stepped hole are sealed by a corrosion-resistant and waterproof first sealing ring 1, and the first sealing ring 1 is sleeved on the inner tube 3. A gap 19 is provided between the two end edges of the inner tube 3 and the end of the stepped hole 18 away from the inner tube 3. The gap 19 is used to provide a buffer space for the second flange under axial external force to prevent it from colliding with the inner tube 3 under axial external force. The first sealing ring 1 is used to achieve sealing between the inner tube 3 and the through hole of the second flange 8 to prevent the electrolyte from flowing out of the gap 19, causing leakage or entering the gap between the outer tube 5 and the inner tube 3.

[0029] In the present invention, the inner tube 3 is preferably made of silicon carbide material. The thermal conductivity of silicon carbide is usually 100-490W / (m·K) and has excellent strong alkali resistance and insulation performance, so it can be used in liquid flow batteries. The second flange, outer tube, support seat and rubber pad at both ends are assembled into a load-bearing and waterproof integrated shell structure through the bolt assembly 14 to alleviate the bump damage caused to the silicon carbide inner tube by external force.

[0030] like Figure 2 As shown, a corrosion-resistant and waterproof second sealing ring 2 is provided between the support seat 9 and the second flange 8 to further seal and waterproof the gap between the outer tube 5 and the inner tube 3 to prevent external liquid from entering the gap.

[0031] like Figure 2 As shown, a through hole 15 is provided on one of the support seats 9 for the cable 7 of the PTC heating group 13 to extend out, and a waterproof silica gel 6 is provided between the through hole 15 and the cable 7 to ensure the waterproof effect of this position.

[0032] like Figure 2As shown, the outer tube 5 is wrapped with an insulation layer 11, and a heat shrink sleeve 12 is arranged outside the insulation layer 11. These two components are non-essential components and can be removed in actual use. Of course, in addition to the insulation function, the insulation layer 11 can also play a buffering role, which can further improve the ability to resist external forces. The insulation layer 11 adopts aluminum silicate insulation cotton.

[0033] In the present invention, the support seat 9 is made of polyhexamethylene adipamide (PA66) and glass fiber material, which can increase the strength and play an insulating role; the second flange 8 is made of homopolymer polypropylene material, which has excellent chemical corrosion resistance, wear resistance, high temperature resistance, corrosion resistance, aging resistance and insulation; the first sealing ring 1 and the second sealing ring 2 are both made of ethylene propylene diene monomer (EPDM) rubber.

[0034] like Figure 2 As shown, an NTC temperature sensor 17 is provided on the outer wall of the inner tube 3 to monitor the temperature of the inner tube 3 .

[0035] The present invention has the following advantages:

[0036] In order to solve the incompatibility between strong alkali corrosion resistance and heating efficiency, ceramic materials, especially silicon carbide materials, are selected. Their thermal conductivity is usually 100-490W / (m·K) and they have excellent strong alkali resistance, thus meeting the requirements of strong alkali resistance and high thermal conductivity.

[0037] The electric heating tube is replaced with a PTC heating core, and the maximum temperature of the core with self-limiting temperature characteristics does not exceed 200°C. When the liquid is 45°C and the flow rate is 300L / min, the surface temperature of the silicon carbide inner tube (3) does not exceed 50°C. The NTC (17) is mainly manifested in low flow rate or dry burning state, and the temperature changes to control the temperature, meet the use requirements, and can avoid the problem of electrolyte overheating.

[0038] The whole product is sealed and waterproofed by the second flange, the support seat, the first flange, the sealing ring and the rubber pad. Since the silicon carbide inner tube has high hardness but weak toughness, the outer tube is assembled with the aforementioned accessories to form an integrated load-bearing and waterproof outer shell, thereby alleviating the problem of electrolyte leakage caused by collision damage to the silicon carbide inner tube due to external forces.

Claims

1. A PTC heater for a flow battery, characterized in that: The invention comprises an inner tube (3), an outer tube (5) and a PTC heating group (13), wherein the inner tube (3) is made of an insulating, corrosion-resistant material with high thermal conductivity, the outer tube (5) is arranged outside the inner tube (3), a gap is arranged between the outer tube (5) and the inner tube (3), the PTC heating group (13) is arranged in the gap, first flanges (4) connected to the outer tube (5) are arranged at both ends, the first flanges (4) are provided with first flange through holes, non-metallic support seats (9) are respectively arranged at both ends of the outer tube (5), the support seats (9) are in a circular shape, an end of the support seat (9) opposite to the first flange (4) is provided with an extended edge (16), the edge (16) abuts against the first flange (4), the edge (16) is provided with a support seat through hole opposite to the first flange through hole, the inner tube (3) passes through the support seat (9), and the inner tube (3) passes through the support seat (9). A non-metallic second flange (8) is provided at one end of the support seat (9) away from the outer tube (5). The second flange (8) is connected and fixed to the support seat (9) and the first flange (4) by a bolt assembly (14). The center of the second flange (8) has a through hole. The end of the center through hole of the second flange (8) facing the outer tube (5) is a stepped hole. The inner tube (3) extends into the stepped hole. The inner tube (3) and the stepped hole are sealed by a corrosion-resistant and waterproof first sealing ring (1). The first sealing ring (1) is sleeved on the inner tube 3. A gap (19) is provided between the two end edges of the inner tube (3) and the end of the stepped hole away from the inner tube (3). A through hole (15) for the cable (7) of the PTC heating group (13) to extend is provided on one of the support seats (9). A waterproof silica gel (6) is provided between the through hole (15) and the cable (7).

2. The PTC heater for a flow battery according to claim 1, characterized in that: The inner tube (3) is made of ceramic material.

3. The PTC heater for a flow battery according to claim 2, characterized in that: The inner tube (3) is made of silicon carbide material.

4. The PTC heater for a flow battery according to any one of claims 1 to 3, characterized in that: A corrosion-resistant and waterproof second sealing ring (2) is provided between the support seat (9) and the second flange (8).

5. The PTC heater for a flow battery according to claim 4, characterized in that: A corrosion-resistant and waterproof rubber pad (10) is provided between the first flange (4) and the support seat (9).

6. The PTC heater for a flow battery according to claim 5, characterized in that: The outer tube (5) is wrapped with a thermal insulation layer (11).

7. The PTC heater for a flow battery according to claim 6, characterized in that: A heat shrink tubing (12) is provided outside the thermal insulation layer (11).

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