Device for controlling RTO front-end safe air intake

Abstract

The utility model belongs to the technical field of automatic control of instruments, and provides a device for controlling safe air intake at the front end of an RTO. The gas-liquid separation tank collects waste gas from each unit of a plant area, and the gas-liquid separation tank sends the waste gas into RTO equipment through a pipeline for combustion treatment, so that the treated waste gas discharged into the atmosphere meets the environmental protection requirement. The content of oxygen in the waste gas entering the RTO equipment is uncertain, and in order to ensure that the waste gas is not in the explosion limit, the volume concentration of the oxygen in the waste gas is required not to exceed the interlocking value alpha. According to the utility model, multiple explosion-proof measures are taken; the first oxygen analyzer and the third oxygen analyzer are used for valuing, so that high safety and high availability can be ensured; 2, during resetting, CO2 or N2 can ensure that the oxygen concentration of the entered waste gas does not exceed a dangerous value; and thirdly, under a more harsh condition, the two gas-liquid separation tanks ensure that more waste gas can be contained.

Description

Technical Field

[0001] The utility model belongs to the technical field of automatic control of instruments, designs a process and instrument flow for controlling the air intake at the front end of an RTO, and particularly relates to a safety control device for the air intake at the front end of an RTO in an explosive gas environment. Background Art

[0002] The principle of the regenerative thermal incinerator (RTO) is to use natural gas thermal oxidation to heat the organic waste gas to above 750°C, and after staying in the combustion chamber for 0.7 to 1.0 seconds, the VOCs in the waste gas are oxidized and decomposed into CO2 and H2O.

[0003] When the concentration of combustible gas or vapor in the air is lower than the lower explosion limit or higher than the upper explosion limit, the gas environment cannot explode.

[0004] The high-concentration exhaust gas from various units in the factory is collected in the gas-liquid separation tank, and the exhaust gas is sent to the RTO equipment through the pipeline through the pressure difference for combustion treatment. Therefore, the exhaust gas concentration entering the RTO is required to be lower than the lower explosion limit or higher than the upper explosion limit. Since the exhaust gas is a high-concentration exhaust gas, the utility model requires that the exhaust gas concentration is higher than the upper explosion limit. Utility Model Content

[0005] The utility model aims to provide a method for controlling the safe air intake of the front end of an RTO.

[0006] The technical solution of this utility model:

[0007] A device for controlling the safe air intake of an RTO front end, mainly comprising a first gas-liquid separation tank 1, a second gas-liquid separation tank 2, a first oxygen analyzer 3, a second oxygen analyzer 4, a third oxygen analyzer 5, a fan 6, a first switch valve 7, a second switch valve 8, a first pipeline 9, a flow meter 10, a regulating valve 11, an ignition controller 12, an RTO device 13, a second pipeline 14, a third pipeline 15 and a fourth pipeline 16, wherein the oxygen analyzer, the fan 6, the switch valve, the flow meter 10, the regulating valve 11 and the ignition controller 12 are all connected to a programmable logic controller (PLC), and the programmable logic controller realizes the control of the device through collected signals and settings;

[0008] The waste gas from each unit of the plant enters the first gas-liquid separation tank 1 and the second gas-liquid separation tank 2 through the first pipeline 9. After the first gas-liquid separation tank 1 and the second gas-liquid separation tank 2 are merged through the pipeline, they are connected to the ignition controller 12. Three oxygen analyzers and a first switch valve 7 are sequentially arranged on the first pipeline 9 between the gas-liquid separation tank and the ignition controller 12; CO2 or N2 gas is connected to the ignition controller 12 through the fourth pipeline 16, and the fourth pipeline 16 is provided with a flow meter 10 and a regulating valve 11; the ignition controller 12 is connected to the RTO equipment 13; the fan 6 is connected to the ignition controller 12 through the third pipeline 15, and a second switch valve 8 is arranged on the third pipeline 15 of the two.

[0009] The gas-liquid separation tank collects waste gas from various units in the plant area, and the gas-liquid separation tank sends the waste gas to the RTO device 13 through the second pipeline 14 for combustion treatment, ensuring that the waste gas discharged into the atmosphere after treatment meets environmental protection requirements. The oxygen content in the waste gas entering the RTO device 13 is uncertain. In order to ensure that the waste gas is not at the explosion limit, the oxygen volume concentration in the waste gas is required not to exceed the interlock value α.

[0010] The normal pressure value of the gas-liquid separation tank is between 0.2kPa and 0.5kPa. Under the action of pressure difference, the exhaust gas enters the RTO equipment 13 through the second pipeline 14. The flow rate of the exhaust gas is set to βm / s. During normal transportation, the fan 6, the first switch valve 7, and the second switch valve 8 are all in the open state, and the regulating valve 11 is in the closed state; when two values ​​of the three oxygen analyzers are higher than α, the fan 6, the first switch valve 7, and the second switch valve 8 are closed to prevent the exhaust gas from entering the RTO equipment 13.

[0011] When resetting, the regulating valve 11 is first opened. At this time, the opening of the regulating valve 11 is adjusted by the flow meter 10. The set value of the flow meter 10 is calculated by the oxygen analyzer value, and the calculation is as follows:

[0012]

[0013] Where x is the oxygen analyzer value; y is the CO2 or N2 flow rate;

[0014] After the regulating valve 11 is opened, the first switch valve 7, the second switch valve 8 and the fan 6 are opened in sequence;

[0015] When the distance from the oxygen analyzer to the first switch valve 7 is a meter, the response time of the oxygen analyzer on the programmable logic controller is b seconds, and the response time of the first switch valve 7 on the programmable logic controller is c seconds, the following relationship is guaranteed:

[0016]

[0017] This ensures that when the measured oxygen content of the exhaust gas exceeds the standard, the exhaust gas cannot enter the RTO device 13 .

[0018] In special cases, when the exhaust gas does not meet the conditions for entering the RTO device 13 and the pressure in the first gas-liquid separation tank 1 is too high or cannot accommodate more exhaust gas, the second gas-liquid separation tank 2 is activated and the exhaust gas will enter the second gas-liquid separation tank 2.

[0019] The effects and benefits of the utility model are: the utility model is equipped with multiple explosion-proof measures; first, three oxygen analyzers are used to take values, which ensures high safety and high availability; second, when resetting, CO2 or N2 can ensure that the oxygen concentration of the incoming exhaust gas does not exceed the dangerous value; third, in more demanding situations, two gas-liquid separation tanks ensure that more exhaust gas can be accommodated. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The utility model discloses a method for controlling the safe air intake of the front end of an RTO.

[0021] In the figure: 1 first gas-liquid separation tank, 2 second gas-liquid separation tank, 3 first oxygen analyzer, 4 second oxygen analyzer, 5 third oxygen analyzer, 6 fan, 7 first switch valve, 8 second switch valve, 9 first pipeline, 10 flow meter, 11 regulating valve, 12 ignition controller, 13 RTO equipment, 14 second pipeline; 15 third pipeline; 16 fourth pipeline. DETAILED DESCRIPTION

[0022] The specific implementation of the utility model is described in detail below in combination with the technical scheme and the accompanying drawings.

[0023] Example:

[0024] The oxygen content in the exhaust gas entering the RTO is uncertain. In order to ensure that the exhaust gas is not within the explosion limit, the utility model requires that the oxygen concentration in the exhaust gas does not exceed 5%.

[0025] The normal pressure value of the gas-liquid separation tank is between 0.2kPa and 0.5kPa. Under the action of pressure difference, the exhaust gas enters the RTO through the pipeline. The flow rate of the exhaust gas is calculated to be 8 m / s. During normal transportation, the fan 6, the first switch valve 7, and the second switch valve 8 are all in the open state, and the regulating valve 11 is in the closed state.

[0026] When two values ​​of the three oxygen analyzers are higher than 5%, the fan 6, the first switch valve 7 and the second switch valve 8 are closed to prevent the exhaust gas from entering the RTO.

[0027] When resetting, the regulating valve is first opened. At this time, the opening of the regulating valve 11 is adjusted by the value of the flow meter 10, and the set value of the flow meter 10 is calculated by the value of the oxygen analyzer.

[0028] The calculation is as follows:

[0029]

[0030] To ensure that the oxygen concentration in the exhaust gas entering the RTO is less than 5%.

[0031] After the regulating valve is opened for 5 seconds, the first switch valve 7, the second switch valve 8 and the fan 6 are opened in sequence.

[0032] When the distance between the oxygen analyzer and the first switch valve 7 is 150 meters, the response time of the oxygen analyzer is 6 seconds, and the response time of the switch valve is 5 seconds, the following relationship is ensured:

[0033]

[0034] It is ensured that when the oxygen content of the measured exhaust gas exceeds 5%, the switch valve is closed in time before the exhaust gas reaches the switch valve, thereby preventing the dangerous exhaust gas from entering the RTO.

[0035] The utility model ensures safety in dangerous environments through multiple measures. In addition, when selecting the oxygen analyzer and the switch valve, attention should be paid to their response time.

Claims

1. A device for controlling the safety air intake at the front end of an RTO, characterized in that: The device mainly comprises a first gas-liquid separation tank (1), a second gas-liquid separation tank (2), a first oxygen analyzer (3), a second oxygen analyzer (4), a third oxygen analyzer (5), a fan (6), a first switch valve (7), a second switch valve (8), a flow meter (10), a regulating valve (11), an ignition controller (12), an RTO device (13) and pipelines, wherein the oxygen analyzer, the fan (6), the switch valve, the flow meter (10), the regulating valve (11) and the ignition controller (12) are all connected to a programmable logic controller, and the programmable logic controller controls the device through collected signals and settings; Waste gas from each unit in the plant enters the first gas-liquid separation tank (1) and the second gas-liquid separation tank (2) through pipelines. After the first gas-liquid separation tank (1) and the second gas-liquid separation tank (2) are merged through pipelines, they are connected to an ignition controller (12). Three oxygen analyzers and a first switch valve (7) are arranged in sequence on the pipeline between the gas-liquid separation tank and the ignition controller (12); CO2 or N2 gas is connected to the ignition controller (12) through pipelines, and the pipelines are provided with a flow meter (10) and a regulating valve (11); the ignition controller (12) is connected to an RTO device (13); the fan (6) is connected to the ignition controller (12) through pipelines, and a second switch valve (8) is arranged on the pipelines between the two.

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