A dynamic positive pressure explosion-proof control device and method

Abstract

The present invention discloses a dynamic positive pressure explosion-proof control device and method, the device comprising: a positive pressure box connected to an air source and receiving dynamic protective gas input from the air source; a vent provided on the positive pressure box; a gas flow meter connected to the vent for obtaining the gas flow rate through the vent; a differential pressure sensor connected to the positive pressure box for measuring the pressure difference between the inside and outside of the positive pressure box, the differential pressure sensor and the gas flow meter both being provided outside the positive pressure box; and a positive pressure control panel connected to the differential pressure sensor and the gas flow meter via the safety barrier for obtaining the pressure difference and comparing it with a preset pressure difference range and / or the gas flow rate with a preset gas flow rate threshold to determine whether to issue an alarm. The present invention uses a dynamic positive pressure method to improve the service life and stability of electrical equipment, and avoids the risk of protective gas entering the dynamic positive pressure explosion-proof control device and generating a release source therein.

Description

Technical Field

[0001] The present invention relates to the field of positive pressure explosion-proof control, and in particular to a dynamic positive pressure explosion-proof control device and method. Background Art

[0002] With the rapid development of my country's industry, the production scale of industries such as petroleum and chemical industry is expanding, and the safety production standards of enterprises need to be continuously improved. Positive pressure explosion-proof systems are widely used in electrical equipment systems working in explosion-hazardous areas. At present, the main explosion-proof measures in hazardous areas of these industries are to use dielectric isolation of explosion sources. All electrical components of the user are installed in a shell filled with pressurized clean medium, so that the flammable and explosive mixed gas in the external environment cannot come into contact with the electric sparks or dangerous temperatures generated by the electrical components during normal operation, thereby achieving the purpose of electrical explosion protection. Traditional positive pressure explosion-proof control systems have the following disadvantages:

[0003] 1. The cabinet of the traditional electrical equipment control cabinet is of positive pressure compensation type. The internal gas fluidity is poor, and it cannot quickly remove the heat generated by the electrical equipment in the control cabinet, which affects the service life and stability of the electrical equipment. In addition, the exhaust speed of this control cabinet is slow, resulting in a long time for gas replacement in the control cabinet, which is very inconvenient for on-site operation. In addition, the traditional positive pressure compensation type is static positive pressure compensation. Positive pressure adjustment will also make the pressure in the control cabinet unstable.

[0004] 2. Traditional electrical equipment control cabinets require special explosion-proof solenoid valves and other live equipment to control the pressure inside the control cabinet to achieve pressure compensation or pressure release. If the electrical equipment control cabinet is not thoroughly ventilated during the initial purge phase, explosive gas will remain, leaving a safety hazard.

[0005] 3. Traditional positive pressure explosion-proof control systems place sensors used to measure air pressure and airflow inside electrical equipment control cabinets. If the air source leaks, the internal and external spaces will be connected, leading to the risk of explosion.

[0006] 4. Traditional positive pressure explosion-proof control systems all process on-site alarms, but such sites are all explosive hazardous areas, and the number of people going there should be reduced, resulting in the inability to quickly detect alarms and handle problems in a timely manner. Summary of the Invention

[0007] To address the above technical issues, the present invention provides a dynamic positive pressure explosion-proof control device and method, which can maintain the pressure of the protective gas inside the electrical equipment control cabinet higher than the external atmospheric pressure, preventing external explosive gases from entering the electrical equipment control cabinet to achieve the purpose of explosion protection, while also achieving a dynamic ventilation type of the protective gas inside the cabinet. The present invention provides the following technical solutions:

[0008] A dynamic positive pressure explosion-proof control device, comprising:

[0009] A positive pressure box is connected to a gas source and receives dynamic protective gas inputted by the gas source; the positive pressure box is provided with an air release port;

[0010] a gas flow meter connected to the gas vent and used to obtain the gas flow rate passing through the gas vent;

[0011] A differential pressure sensor is connected to the positive pressure box and is used to measure the pressure difference between the inside and outside of the positive pressure box. The differential pressure sensor and the gas flow meter are both arranged outside the positive pressure box.

[0012] The positive pressure control panel is connected to the differential pressure sensor and the gas flow meter through a safety barrier to obtain the pressure difference and compare it with a preset pressure difference range and / or the gas flow rate with a preset gas flow rate threshold to determine whether to alarm.

[0013] Preferably, an explosion-proof infrared camera is provided in the positive pressure box.

[0014] Preferably, the flow rate of the dynamic protection gas filled into the positive pressure box by the gas source and the flow rate of the air vent are both manually adjusted by the one-way vent valve.

[0015] Preferably, the positive pressure control board is powered by a DC regulated power supply, and the DC regulated power supply also powers the gas flow meter and the differential pressure sensor through the safety barrier. The positive pressure control board, the DC regulated power supply and the safety barrier are all arranged in a flameproof enclosure.

[0016] The present invention also provides a control method using the above-mentioned dynamic positive pressure explosion-proof control device, comprising the following steps:

[0017] Adjust the gas source flow rate to provide dynamic protective gas for the positive pressure box;

[0018] Obtain the gas flow rate at the vent of the positive pressure box and the pressure difference between the inside and outside of the positive pressure box;

[0019] The determination of whether to issue an alarm is made based on the comparison between the air pressure difference and a preset air pressure difference range and / or the gas flow rate and a preset gas flow rate threshold.

[0020] Preferably, after obtaining the gas flow rate of the positive pressure box vent and the pressure difference inside and outside the positive pressure box, the following steps are also included: when the pressure difference between the inside and outside of the positive pressure box and the flow rate of the exhaust gas reach the set threshold, start recording the volume of the exhaust gas, and when the exhaust gas volume exceeds five times the volume of the positive pressure box cavity, the air purge ends; if there is no alarm after the air purge ends, the dynamic positive pressure explosion-proof control device will turn on the power inside the positive pressure box cavity and enter the normal monitoring stage.

[0021] Preferably, before obtaining the gas flow rate of the positive pressure box vent and the pressure difference inside and outside the positive pressure box, the following steps are also included: powering the explosion-proof infrared camera, and only after the explosion-proof infrared camera outputs the video signal normally, start real-time monitoring of the pressure difference inside and outside the positive pressure box cavity and the flow rate of the exhaust gas.

[0022] Preferably, after entering the normal monitoring stage, the following steps are further included: when the differential pressure sensor detects that the pressure difference between the inside and outside of the positive pressure box continuously deviates from the normal range or the deviation is too large, it will automatically alarm.

[0023] Preferably, before providing dynamic protective gas to the positive pressure box, the following steps are also included: after the dynamic positive pressure explosion-proof control device is started, it is first initialized.

[0024] Preferably, the regulating gas source flow rate is obtained by manual adjustment.

[0025] The beneficial effects of the dynamic positive pressure explosion-proof control device of the present invention are as follows: the dynamic positive pressure explosion-proof control device realizes the clean medium flowing in the electrical system with dynamic positive pressure, quickly takes away the heat generated by the instruments and meters in the target electrical system, avoids the influence of the temperature in the cabinet on the electrical equipment, and improves the service life and stability of the electrical equipment; it only needs to add a one-way vent valve at the input and output ports to realize the continuous input of protective gas, and no longer needs solenoid valves and other electrical equipment to control the on and off of the gas path, which can ensure the closedness of the system, simplify the electrical equipment of the control system, and improve the stability of the system; the differential pressure sensor and the flow sensor are directly connected to the target The control cabinet of the standard electrical system is connected, so that the measurement of air pressure and airflow is placed outside the dynamic positive pressure explosion-proof control device, and only the collected signals are connected to the dynamic positive pressure explosion-proof control device, thereby avoiding the risk of protective gas entering the dynamic positive pressure explosion-proof control device and generating a release source inside it, and also avoiding a factor that may cause an explosion; in addition to providing an explosion-proof power indicator light and sound and light alarm on its own system, the dynamic positive pressure explosion-proof control device also provides serial asynchronous semi-duplex RS485 communication based on the MODBUS-RTU protocol, which can realize remote alarm in the monitoring room within 1000 meters so that timely measures can be taken. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of a dynamic positive pressure explosion-proof control device;

[0027] Figure 2 This is the three-view drawing of the explosion-proof electrical control box;

[0028] Figure 3 This is the operating status flow chart of the dynamic positive pressure explosion-proof control device;

[0029] Figure 4 This is the flow chart of the wind sweeping mode;

[0030] Figure 5 This is the monitoring mode control flow chart. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] Example

[0033] The positive pressure box 1 is connected to the gas source and receives the dynamic protective gas input by the gas source; the positive pressure box 1 is provided with an air release port; the positive pressure box 1 adopts a PX type positive pressure box.

[0034] A gas flow meter 2, connected to the gas vent, for obtaining the gas flow rate passing through the gas vent;

[0035] A differential pressure sensor 3 is connected to the positive pressure box 1 and is used to measure the pressure difference between the inside and outside of the positive pressure box 1. The differential pressure sensor 3 and the gas flow meter 2 are both arranged outside the positive pressure box 1;

[0036] The positive pressure control board 4 is connected to the differential pressure sensor 3 and the gas flow meter 2 through the safety barrier 5 to obtain the pressure difference and compare it with the preset pressure difference range and / or the gas flow rate with the preset gas flow rate threshold to determine whether to alarm.

[0037] In this embodiment, an explosion-proof infrared camera is provided in the positive pressure box 1 .

[0038] In this embodiment, the flow rate of the dynamic protection gas filled into the positive pressure box 1 by the gas source and the flow rate of the air vent are both manually adjusted by the one-way vent valve.

[0039] In this embodiment, the positive pressure control board 4 is powered by a DC regulated power supply 6, and the DC regulated power supply 6 also powers the gas flow meter 2 and the differential pressure sensor 3 through the safety barrier 5. The positive pressure control board 4, the DC regulated power supply 6 and the safety barrier 5 are all arranged in a flameproof enclosure.

[0040] The target electrical system is located in the positive pressure box 1, and the interior of the positive pressure box 1 always maintains a positive pressure state. According to the requirements of the national standard GB3836.20-2010 / IEC 60079-26:2006, the pressure difference between the interior of the positive pressure box 1 and the outside is not less than 50pa, and at the initial moment, the interior of the positive pressure box 1 cavity needs to be purged so that the volume of the discharged gas is not less than five times the volume of the positive pressure box 1 cavity.

[0041] The dynamic positive pressure explosion-proof control device mainly includes a flameproof shell, a differential pressure sensor 3, a gas flow meter 2, an explosion-proof infrared camera and an explosion-proof sound and light alarm.

[0042] Preferably, the shell of the explosion-proof electrical control box 301 is made of steel plate welding, cast aluminum alloy or 304 stainless steel die-casting, the surface is high-voltage electrostatic sprayed to prevent static electricity, the explosion-proof joint surface is smooth, and anti-rust oil is evenly applied to the explosion-proof joint surface. Generally, a composite structure composed of a flameproof shell and an increased safety shell is adopted.

[0043] Preferably, the flameproof housing can be equipped with explosion-proof components such as buttons, signal lights, transfer switches and instruments, as well as functional modules such as AC contactors, thermal relays and thermostats; the increased safety housing can be equipped with explosion-proof components such as buttons, control switches and instruments.

[0044] Preferably, the front of the explosion-proof shell includes four control alarm units, namely an explosion-proof self-locking switch, a 12V explosion-proof green power indicator light, a 12V explosion-proof red alarm indicator light, and a 12V explosion-proof flashing buzzer, all of which are connected to the positive pressure control panel; there are four M20*1.5 threaded wire outlet holes on the four sides, which are convenient for using explosion-proof flexible pipes to connect the explosion-proof shell and the sensor.

[0045] Preferably, the explosion-proof components and functional modules in the explosion-proof enclosure can be arranged according to user requirements to achieve multiple functions. The wiring can be done by steel pipes, cables or explosion-proof hoses. It is developed and manufactured in full accordance with the standard requirements of the National Standard of the People's Republic of China GB3836.2 "Explosive Atmospheres" Part 2: Equipment protected by explosion-proof enclosure "d", and has relevant certification certificates, making it safe and reliable to use.

[0046] Preferably, the differential pressure sensor 3 is used to monitor the pressure difference between the inside and outside of the positive pressure box 1 in real time.

[0047] Preferably, the gas flow meter 2 is used to monitor the flow rate of the gas discharged from the positive pressure box 1 in real time.

[0048] Preferably, the explosion-proof infrared camera is arranged inside the positive pressure box 1, connected to the positive pressure control board and DC regulated power supply in the flameproof shell, and the collected video signal is transmitted to the switch in the monitoring room through a Category 5e network cable.

[0049] Preferably, the explosion-proof sound and light alarm supports RS485 communication protocol, is connected to the positive pressure control board 4 through a 485 line, and is controlled by a signal sent by the positive pressure control board 4.

[0050] The working principle of the dynamic positive pressure explosion-proof control device: Because flammable and explosive dangerous gases may enter the cavity of positive pressure box 1, a purge is required before the power supply system inside the cavity of positive pressure box 1 is powered. According to national standards, the exhaust gas volume must be no less than five times the volume of the cavity of positive pressure box 1. The exhaust gas flow rate is monitored and the volume of the exhaust gas is calculated. The power supply inside the cavity of positive pressure box 1 is not activated until the standard is met.

[0051] Example 2

[0052] This embodiment provides a control method using the dynamic positive pressure explosion-proof control device in embodiment 1, such as Figure 2 As shown, the following steps are included:

[0053] S100, adjusting the gas source flow rate to provide dynamic protective gas for the positive pressure box 1;

[0054] S200, obtaining the gas flow rate of the vent port of the positive pressure box 1 and the pressure difference between the inside and outside of the positive pressure box 1;

[0055] S300 , comparing the air pressure difference with a preset air pressure difference range and / or the gas flow rate with a preset gas flow rate threshold to determine whether to issue an alarm.

[0056] In this embodiment, after obtaining the gas flow rate of the air vent of the positive pressure box 1 and the pressure difference inside and outside the positive pressure box 1, the following steps are also included: when the pressure difference between the inside and outside of the positive pressure box 1 and the flow rate of the exhaust gas reach the set threshold, the volume of the exhaust gas is recorded. When the volume of the exhaust gas exceeds five times the volume of the cavity of the positive pressure box 1, the air purge ends; if there is no alarm after the air purge ends, the dynamic positive pressure explosion-proof control device will turn on the power inside the cavity of the positive pressure box 1 and enter the normal monitoring stage.

[0057] In this embodiment, before obtaining the gas flow rate of the air vent of the positive pressure box 1 and the pressure difference inside and outside the positive pressure box 1, the following steps are also included: powering the explosion-proof infrared camera, and only after the explosion-proof infrared camera outputs the video signal normally, start real-time monitoring of the pressure difference inside and outside the cavity of the positive pressure box 1 and the flow rate of the exhaust gas.

[0058] In this embodiment, after entering the normal monitoring stage, the following steps are also included: if the differential pressure sensor 3 detects that the pressure difference between the inside and outside of the positive pressure box 1 continues to deviate from the normal range or the deviation is too large, it will automatically alarm.

[0059] In this embodiment, the following steps are further included before providing dynamic protective gas to the positive pressure box 1: after the dynamic positive pressure explosion-proof control device is started, it is first initialized.

[0060] In this embodiment, the flow rate of the regulated gas source is obtained by manual adjustment.

[0061] In this embodiment, the control process of the dynamic positive pressure explosion-proof control device in Example 1 is as follows:

[0062] 1. Automatic air sweeping and ventilation

[0063] Automatic air purge and ventilation is a purging process. After the dynamic positive pressure explosion-proof control device is initialized, the gas five times the volume of the positive pressure box 1 cavity is replaced through a certain period of purging, making the positive pressure box 1 a safe environment.

[0064] 2. Low pressure warning and over pressure alarm

[0065] When the pressure in the positive pressure box 1 is lower than or higher than the set threshold of the pressure detection switch, the dynamic positive pressure explosion-proof control device will send a signal to control the sound and light alarm, explosion-proof buzzer, and alarm indicator light to work.

[0066] 3. Automatically cut off power supply when low voltage is applied

[0067] When the pressure in the positive pressure box 1 is less than 200 Pa, the pressure detection switch inside the positive pressure box 1 detects a low pressure signal and issues a low voltage power-off instruction to cut off the power supply in the cavity of the positive pressure box 1.

[0068] like Figure 3 As shown in the figure, the operating status of the dynamic positive pressure explosion-proof control device includes four stages: starting the air sweeping S01, air sweeping S02, normal monitoring S03 and alarm S04. The operating status of each stage is processed and switched through the timer interrupt service. The specific control method is as follows:

[0069] Start: After the dynamic positive pressure explosion-proof control device is started, it is initialized first and then enters the start-up purge phase S01.

[0070] Start the purge stage S01: When the pressure difference between the inside and outside of the positive pressure box 1 and the flow rate of the exhaust gas are automatically monitored and reach the set threshold, the dynamic positive pressure explosion-proof control device enters the purge stage S02.

[0071] Sweep phase S02: Figure 4 As shown, after entering the purge stage S02, the purge flag in the dynamic positive pressure explosion-proof control device 03 will be turned on, and the time period during which the gas flow rate reaches the set threshold will be timed. When the flow rate of the exhaust gas from the positive pressure box 1 is lower than the set threshold, if the timing is detected to be overtime, and then the changes caused by the unstable gas source are filtered out, the dynamic positive pressure explosion-proof control device 03 will automatically alarm; when the pressure difference between the inside and outside of the positive pressure box 1 and the flow rate of the exhaust gas exceed the set threshold, the exhaust timing starts, and the volume of the exhaust gas starts to be recorded at the same time. When the volume of the exhaust gas exceeds five times the volume of the cavity of the positive pressure box 1, the purge ends; if there is no alarm after the purge ends, the dynamic positive pressure explosion-proof control device 03 will turn on the power inside the cavity of the positive pressure box 1 and enter the normal monitoring stage S03.

[0072] Normal monitoring stage S03: The dynamic positive pressure explosion-proof control device 03 first supplies power to the explosion-proof infrared camera 304. After the explosion-proof infrared camera 304 transmits the video signal normally, it starts to monitor the air pressure difference inside and outside the positive pressure box 1 cavity and the flow rate of the exhaust gas in real time to ensure that the dynamic positive pressure explosion-proof control device 03 is in a stable operating state.

[0073] Alarm stage S04: If Figure 5 As shown, in the normal monitoring stage S03 of the dynamic positive pressure explosion-proof control device 03, the differential pressure sensor 302 will issue an early warning when it detects that the air pressure difference between the inside and outside of the positive pressure box 1 deviates from the normal range. When the air pressure difference deviates too much continuously, it will automatically count. When the number of excessive deviations reaches the upper limit, an alarm will be issued.

[0074] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A dynamic positive pressure explosion-proof control device, characterized in that: include: A positive pressure box is connected to a gas source and receives dynamic protective gas input from the gas source; The positive pressure box is provided with an air release port; a gas flow meter connected to the gas vent and used to obtain the gas flow rate passing through the gas vent; A differential pressure sensor is connected to the positive pressure box and is used to measure the pressure difference between the inside and outside of the positive pressure box. The differential pressure sensor and the gas flow meter are both arranged outside the positive pressure box. The positive pressure control board connects the differential pressure sensor and the gas flow meter through a safety barrier, obtains the pressure difference and compares it with a preset pressure difference range and / or the gas flow rate with a preset gas flow rate threshold to decide whether to alarm; when the pressure difference inside and outside the positive pressure box and the flow rate of the exhaust gas reach the set threshold, the volume of the exhaust gas starts to be recorded, and when the volume of the exhaust gas exceeds five times the volume of the positive pressure box cavity, the air purge ends; if there is no alarm after the air purge ends, the dynamic positive pressure explosion-proof control device will turn on the power supply inside the positive pressure box cavity and enter the normal monitoring stage; the pressure difference inside and outside the positive pressure box and the gas flow rate are monitored in real time to ensure that the dynamic positive pressure explosion-proof control device is in a stable operating state.

2. A dynamic positive pressure explosion-proof control device according to claim 1, characterized in that: An explosion-proof infrared camera is arranged in the positive pressure box.

3. A dynamic positive pressure explosion-proof control device according to claim 1 or 2, characterized in that: The flow rate of dynamic protection gas from the air source of the dynamic positive pressure explosion-proof control device to the positive pressure box and the flow rate of the air release port are both manually adjusted by the one-way vent valve.

4. A dynamic positive pressure explosion-proof control device according to claim 1, characterized in that: The positive pressure control board is powered by a DC regulated power supply, which also powers the gas flow meter and the differential pressure sensor through the safety barrier. The positive pressure control board, the DC regulated power supply and the safety barrier are all arranged in a dynamic positive pressure explosion-proof control device inside a flameproof enclosure.

5. A dynamic positive pressure explosion-proof control method, characterized in that: The dynamic positive pressure explosion-proof control device according to any one of claims 1 to 4 is used, comprising the following steps: Adjust the gas source flow rate to provide dynamic protective gas for the positive pressure box; Obtain the gas flow rate at the vent of the positive pressure box and the pressure difference between the inside and outside of the positive pressure box; Comparing the gas pressure difference with a preset gas pressure difference range and / or the gas flow rate with a preset gas flow rate threshold to determine whether to issue an alarm; After obtaining the gas flow rate of the positive pressure box vent and the pressure difference inside and outside the positive pressure box, the following steps are also included: when the pressure difference inside and outside the positive pressure box and the flow rate of the exhaust gas reach the set threshold, the volume of the exhaust gas is recorded. When the exhaust gas volume exceeds five times the volume of the positive pressure box cavity, the air purge ends; if there is no alarm after the air purge ends, the dynamic positive pressure explosion-proof control device will turn on the power inside the positive pressure box cavity and enter the normal monitoring stage.

6. A dynamic positive pressure explosion-proof control method according to claim 5, characterized in that: Before obtaining the gas flow rate of the positive pressure box vent and the pressure difference inside and outside the positive pressure box, the following steps are also included: powering the explosion-proof infrared camera, and only after the explosion-proof infrared camera outputs the video signal normally, it starts to monitor the pressure difference inside and outside the positive pressure box cavity and the flow rate of the exhaust gas in real time.

7. A dynamic positive pressure explosion-proof control method according to claim 6, characterized in that: After entering the normal monitoring stage, the following steps are also included: if the differential pressure sensor detects that the air pressure difference between the inside and outside of the positive pressure box continues to deviate from the normal range or the deviation is too large, it will automatically alarm.

8. A dynamic positive pressure explosion-proof control method according to any one of claims 5 to 7, characterized in that: Before providing dynamic protective gas to the positive pressure box, the following steps are also included: after the dynamic positive pressure explosion-proof control device is started, it is first initialized.

9. A dynamic positive pressure explosion-proof control method according to any one of claims 5 to 7, characterized in that: The flow rate of the regulating gas source is obtained by manual adjustment.

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