Explosion-proof Roots blower cylinder body structure

Abstract

The utility model discloses an explosion-proof Roots blower cylinder body structure which comprises an impeller, an electric brush, a machine shell, an impeller shaft and a monitoring system. The surface of the impeller is covered with a plasma spraying tungsten carbide-cobalt coating; an annular conductive area is arranged on one end face of the impeller, the electric brush is in elastic compression joint with the conductive area of the impeller through a spring, the electric brush is grounded through a grounding wire, and the electric brush is in clearance fit with an optimized impeller-machine shell through plasma spraying of a tungsten carbide-cobalt coating, so that double anti-explosion protection is achieved; the wear rate of the impeller can be reduced to below 1 / 5 of that of a traditional coating, and gap expansion and friction sparks caused by wear are effectively prevented.

Description

Technical Field

[0001] This utility model relates to the field of Roots blower technology, and in particular to an explosion-proof Roots blower cylinder structure. Background Technology

[0002] Roots blowers, as a type of positive displacement gas conveying device, are widely used in chemical, coal mining, and oil and gas industries due to their advantages such as simple structure, stable operation, and constant flow rate. This device achieves forced gas delivery through two meshing impellers rotating in opposite directions within the casing, making it particularly suitable for processes requiring stable flow rates. However, traditional Roots blowers face severe explosion-proof safety challenges when used in flammable and explosive environments.

[0003] The core issue of explosion-proof design lies in the mechanical sparks and electrostatic accumulation that may be generated during the high-speed rotation of the impeller. When the gap between the impeller and the casing increases to more than 0.3 mm due to wear, the spark temperature generated by metal-to-metal collision can reach over 600℃, far exceeding the minimum ignition temperature of flammable gases such as methane (537℃) and hydrogen (560℃). Simultaneously, the surface electrostatic potential of traditional non-conductive coatings can accumulate to over 5000V in a dry environment, with a discharge energy reaching 0.28mJ, exceeding the minimum ignition energy (0.26mJ) of Class IIA gases (such as propane). Existing solutions, such as adding explosion-proof motors or inert gas protection systems, not only increase equipment costs by more than 40% but also suffer from technical bottlenecks such as response delay (>2s) and complex maintenance. Utility Model Content

[0004] Purpose of the invention: The purpose of this utility model is to provide an explosion-proof cylinder structure for a Roots blower. By using a plasma-sprayed tungsten carbide-cobalt coating and an optimized impeller-casing clearance, dual explosion-proof protection is achieved: the tungsten carbide-cobalt coating has excellent wear resistance (hardness ≥1100HV), which can reduce the impeller wear rate to less than 1 / 5 of that of traditional coatings, effectively preventing the widening of the clearance and friction sparks caused by wear.

[0005] Technical solution:

[0006] An explosion-proof Roots blower cylinder structure includes an impeller, a brush, a casing, an impeller shaft, and a monitoring system; the surface of the impeller is covered with a plasma-sprayed tungsten carbide-cobalt coating; an annular conductive area is provided on one end face of the impeller, the brush is elastically pressed against the conductive area of ​​the impeller by a spring, and the brush is grounded through a grounding wire.

[0007] Furthermore, the gap between the impeller and the casing is 0.15-0.25 mm.

[0008] Furthermore, the monitoring system includes an infrared temperature sensor and a gas concentration sensor, which are connected to the control system via wires.

[0009] Furthermore, the contact end of the brush is an annular copper alloy sheet with an inner diameter that is clearance-fitted with the impeller shaft, and the outer diameter of the contact end of the brush is smaller than the minimum outer diameter of the impeller.

[0010] Furthermore, the contact end surface of the brush is coated with a tungsten carbide layer.

[0011] Furthermore, the spring is a disc spring.

[0012] Furthermore, the grounding wire is a copper braided strip.

[0013] Furthermore, one end of the impeller shaft is connected to the motor, and the other end is fixed to the mounting base via a bearing. The spring is fixedly mounted on the spring seat, and the mounting base is located in the middle of the spring seat.

[0014] Furthermore, the housing has a wire groove, and the grounding wire is installed in the wire groove.

[0015] Beneficial effects:

[0016] 1. By using plasma-sprayed tungsten carbide-cobalt coating with optimized impeller-casing clearance, dual explosion-proof protection is achieved: the tungsten carbide-cobalt coating has excellent wear resistance (hardness ≥1100HV), which can reduce the impeller wear rate to less than 1 / 5 of that of traditional coatings, effectively preventing clearance expansion and friction sparks caused by wear.

[0017] The 0.15-0.25mm gap ensures airtightness and avoids direct metal contact, keeping the operating temperature stable below 60℃, which is far below the ignition temperature of combustible gases.

[0018] 3. The design of the annular conductive area and brush assembly creates a highly efficient electrostatic discharge channel: the interface resistance between the conductive area and the tungsten carbide coating is <0.1Ω. Combined with the copper braided grounding wire (resistance ≤4Ω), the electrostatic potential of the impeller surface can be reduced from more than 5000V in the traditional structure to below 50V within the safe range. The electrostatic discharge energy is controlled within 0.05mJ, which is significantly lower than the minimum ignition energy of common combustible gases.

[0019] 4. The coordinated monitoring of infrared temperature sensor and gas concentration sensor, along with a rapid response mechanism, can immediately trigger an alarm and activate protective measures when the temperature exceeds 80℃ or the gas concentration reaches 20% of the lower explosive limit, effectively reducing the risk of accidents. Attached Figure Description

[0020] Figure 1 This is a cross-section of the cylinder body of the Roots blower of this utility model. Figure 1 ;

[0021] Figure 2This is a partially enlarged view of the cylinder body of the Roots blower of this utility model;

[0022] Figure 3 This is a cross-section of the cylinder body of the Roots blower of this utility model. Figure 1 ;

[0023] Figure 4 This is a schematic diagram of the installation of the Roots blower cylinder body of this utility model. Detailed Implementation

[0024] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] like Figure 1-4 As shown, an explosion-proof Roots blower cylinder structure includes an impeller 1, a brush 2, a housing 3, an impeller shaft 4, and a monitoring system; the surface of the impeller 1 is covered with a plasma-sprayed tungsten carbide-cobalt coating; an annular conductive area 11 is provided on one end face of the impeller 1, the brush 2 is elastically pressed against the conductive area 11 of the impeller by a spring 5, and the brush 2 is grounded through a grounding wire 6.

[0027] A dense coating (porosity <1%) is formed on the impeller surface using supersonic plasma spraying, achieving a hardness ≥1100HV and wear resistance more than four times that of traditional nickel-based coatings, fundamentally reducing the risk of frictional sparks caused by impeller wear. An uncoated metal substrate area (3-5mm wide) is left on the impeller end face through machining, forming a conductive interface (resistance <0.1Ω) with the tungsten carbide coating, serving as a physical channel for static electricity discharge. The brush 2 is dynamically pressed against the conductive area 11 by a spring 5, ensuring stable contact even during high-speed impeller rotation (up to 3000rpm) and thermal expansion (axial deformation ±0.5mm), with the contact pressure controlled within the range of 5-10N.

[0028] In this embodiment, the gap between the impeller 1 and the casing is 0.15-0.25 mm. This gap range is optimized through fluid dynamics simulation to ensure airtightness (leakage <3%) while avoiding direct contact and friction between the impeller and the casing. When the gap is >0.25 mm, increased airflow leakage leads to decreased efficiency; when the gap is <0.15 mm, thermal expansion easily causes a collision risk. The high-speed airflow within the gap can carry away frictional heat, and combined with the casing's heat dissipation groove design, it keeps the operating temperature stable below 60℃ (traditional structures often reach 80-100℃).

[0029] In this embodiment, the monitoring system includes an infrared temperature sensor and a gas concentration sensor, which are connected to the control system via wires. The infrared temperature sensor detects the impeller surface temperature in real time with an accuracy of ±0.5℃. When the temperature exceeds 80℃, a level one alarm is triggered, and when it exceeds 100℃, an emergency shutdown is initiated. The gas concentration sensor (catalytic combustion type) detects the methane / hydrogen concentration with a resolution of 0.1% LEL. When the concentration exceeds 20% LEL, inert gas injection is activated. The control system has a response time of <0.5 seconds, which is 4 times faster than traditional mechanical protection devices, effectively preventing chain reactions of explosions.

[0030] In this embodiment, the contact end of the brush 2 is an annular copper alloy sheet with an inner diameter that is clearance-fitted with the impeller shaft, and the outer diameter of the contact end of the brush 2 is smaller than the minimum outer diameter of the impeller. Alternatively, the contact end of the brush 2 may be an annular beryllium copper alloy sheet with an inner diameter that is clearance-fitted with the impeller shaft 4 (clearance 0.1-0.3 mm), and the outer diameter is smaller than the minimum outer diameter of the impeller.

[0031] In this embodiment, the contact end surface of the brush 2 is coated with a tungsten carbide layer.

[0032] In this embodiment, the spring 5 is a disc spring. The nonlinear stiffness characteristics of the disc spring can maintain pressure fluctuation of <±5% when the compression changes by ±10%, which is better than the ±20% fluctuation of the helical spring. The height of a single disc spring is only 5-8mm, which saves 60% of the installation space compared with the helical spring of the same load, and meets the compact structure requirements of the fan.

[0033] In this embodiment, the grounding wire 6 is a copper braided tape. The low resistance (≤4Ω) of the copper braided tape 6 can quickly conduct static charge to the ground, preventing potential accumulation from exceeding the safety threshold of 50V.

[0034] In this embodiment, one end of the impeller shaft 4 is connected to the motor 7, and the other end is fixed to the mounting base 8 via a bearing. The spring 5 is fixedly mounted on the spring seat 9, and the mounting base 8 is located in the middle of the spring seat 9. In this embodiment, a cylindrical roller bearing is used, which can withstand the axial thermal expansion of the impeller. Combined with the double support structure, the shaft end runout is less than 0.02 mm.

[0035] In this embodiment, the housing 3 has a wire groove 10, and the grounding wire 6 is installed in the wire groove.

[0036] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A cylinder body structure for an explosion-proof Roots blower, characterized in that, It includes an impeller (1), a brush (2), a housing (3), an impeller shaft (4), and a monitoring system; the surface of the impeller (1) is covered with a plasma-sprayed tungsten carbide-cobalt coating; an annular conductive area (11) is provided on one end face of the impeller (1), the brush (2) is elastically pressed against the conductive area (11) of the impeller by a spring (5), and the brush (2) is grounded by a grounding wire (6).

2. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, The gap between the impeller (1) and the casing is 0.15-0.25 mm.

3. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, The monitoring system includes an infrared temperature sensor and a gas concentration sensor, which are connected to the control system via wires.

4. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, The contact end of the brush (2) is an annular copper alloy sheet with an inner diameter that is clearance-fitted with the impeller shaft. The outer diameter of the contact end of the brush (2) is smaller than the minimum outer diameter of the impeller.

5. The explosion-proof Roots blower cylinder structure according to claim 4, characterized in that, The contact end surface of the brush (2) is coated with a tungsten carbide layer.

6. The explosion-proof Roots blower cylinder body structure according to claim 1, characterized in that, The spring (5) is a butterfly spring.

7. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, The grounding wire (6) is a copper braided strip.

8. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, One end of the impeller shaft (4) is connected to the motor (7), and the other end is fixed to the mounting base (8) by a bearing. The spring (5) is fixedly mounted on the spring seat (9), and the mounting base (8) is located in the middle of the spring seat (9).

9. The explosion-proof Roots blower cylinder structure according to claim 1, characterized in that, The housing (3) has a wire groove (10), and the grounding wire (6) is installed in the wire groove.

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