Safety interlock protection device for waste acid treatment system

Abstract

The safety interlock protection device of the waste acid treatment system of the present invention relates to the technical field of waste acid treatment. By installing a pressure sensor on the concentration device to detect the pressure inside the concentration device in real time, when the pressure inside the concentration device exceeds the preset value, the supply of high-temperature steam to the waste acid treatment system is stopped, and the three-way valve is switched so that the gas in the waste acid treatment system flows through the pneumatic three-way valve and then flows to the wastewater collection pool after being absorbed by low-pressure steam, thereby avoiding excessive pressure inside the concentration device and solving the problem that the concentration equipment in the prior art may be damaged due to excessive pressure. The present invention is applicable to waste acid treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of waste acid treatment, and particularly to a safety interlock protection device for a waste acid treatment system. Background Art

[0002] The waste acid treatment system is usually for the treatment of nitric acid and sulfuric acid, and uses the different boiling points of sulfuric acid, nitric acid and water for distillation and concentration. Usually, steam heating is adopted. However, direct heating distillation consumes a large amount of steam and requires a high pressure. Therefore, the vast majority adopt vacuum heating distillation and concentration method to achieve the concentration and recovery of sulfuric acid and nitric acid.

[0003] In the existing waste acid treatment system, most of the concentration equipment uses enamel materials. However, the concentration equipment made of enamel materials is prone to cracking of the enamel glaze under positive pressure impact. In the existing waste acid treatment system, due to sudden abnormal conditions such as misoperation, water cut-off, power cut-off, etc., it may cause positive pressure impact on the concentration equipment and damage it, thus affecting the normal use of the equipment and being unable to be repaired. The cost of replacing the equipment is expensive, which brings serious troubles to the stable operation of the waste acid treatment device. Summary of the Invention

[0004] The technical problem to be solved by the present invention: Provide a safety interlock protection device for a waste acid treatment system to solve the problem that the concentration equipment in the prior art may be damaged due to excessive pressure.

[0005] The technical solution adopted by the present invention to solve the above technical problem: The safety interlock protection device for a waste acid treatment system, the waste acid treatment system includes a concentration device, vacuum heating is carried out on the concentration device through high-temperature steam, and waste acid is treated by distillation and concentration method. The waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port; it includes a pressure sensor, a three-way valve, an ejector and a waste water collection tank; the pressure sensor is connected to the concentration device for detecting the pressure in the concentration device; the first end of the three-way valve is connected to the exhaust port of the waste acid treatment system, the second end is connected to the waste gas absorption system, the third end is connected to a fluid inlet of the ejector, and the other fluid inlet of the ejector is connected to low-pressure steam. The outlet of the ejector extends into the sealed liquid level of the waste water collection tank; when the pressure in the concentration device does not exceed the preset value, the waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port and the three-way valve; when the pressure in the concentration device exceeds the preset value, stop providing high-temperature steam to the waste acid treatment system and switch the three-way valve, so that the gas in the waste acid treatment system passes through the pneumatic three-way valve and then flows to the waste water collection tank after being absorbed by the low-pressure steam.

[0006] Further, the concentration device includes a nitric acid concentration device and a sulfuric acid concentration device.

[0007] Further, the nitric acid concentration device includes a nitric acid concentration kettle and a nitric acid concentration tower.

[0008] Further, the sulfuric acid concentration device includes a sulfuric acid concentration kettle and a scrubber.

[0009] Further, the supply of high-temperature steam to the waste acid treatment system is stopped by closing the steam valve.

[0010] Further, the safety interlock protection device of the waste acid treatment system further includes a DCS control system. The DCS control system is respectively connected to the steam valve, the pressure sensor and the three-way valve. The DCS control system controls the opening and closing of the steam valve and switches the flow direction of the three-way valve according to the pressure data of the pressure sensor.

[0011] Further, the formula for calculating the height h at which the outlet of the ejector extends below the sealed liquid level of the wastewater collection tank is: h = (P1 - Pa) / ρg, where h represents the height, P1 represents the exhaust pressure at the outlet of the ejector, Pa represents the standard atmospheric pressure, ρ represents the density of water, and g represents the acceleration due to gravity.

[0012] Advantages of the present invention: The safety interlock protection device of the waste acid treatment system of the present invention installs a pressure sensor on the concentration device to detect the pressure inside the concentration device in real time. When the pressure inside the concentration device exceeds the preset value, the supply of high-temperature steam to the waste acid treatment system is stopped, and the three-way valve is switched, so that the gas in the waste acid treatment system passes through the pneumatic three-way valve and then flows to the wastewater collection tank after being absorbed by the low-pressure steam, thereby avoiding excessive pressure inside the concentration device and solving the problem that the concentration equipment in the prior art may be damaged due to excessive pressure. Description of the Drawings

[0013] Att Figure 1 is a schematic diagram of an embodiment of the safety interlock protection device of the waste acid treatment system of the present invention, where h represents the height at which the outlet of the ejector extends below the sealed liquid level of the wastewater collection tank. Detailed Embodiments

[0014] Safety interlock protection device for waste acid treatment system of the present invention. The waste acid treatment system includes a concentration device, which is vacuum-heated by high-temperature steam, and the waste acid is treated by distillation and concentration. The waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port. It includes a pressure sensor, a three-way valve, an ejector and a waste water collection tank. The pressure sensor is connected to the concentration device for detecting the pressure inside the concentration device. The first end of the three-way valve is connected to the exhaust port of the waste acid treatment system, the second end is connected to the waste gas absorption system, the third end is connected to a fluid inlet of the ejector, the other fluid inlet of the ejector is connected to low-pressure steam, and the outlet of the ejector extends below the sealed liquid level of the waste water collection tank. When the pressure inside the concentration device does not exceed the preset value, the waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port and the three-way valve. When the pressure inside the concentration device exceeds the preset value, the supply of high-temperature steam to the waste acid treatment system is stopped, and the three-way valve is switched, so that the gas in the waste acid treatment system passes through the pneumatic three-way valve and then flows to the waste water collection tank after being absorbed by the low-pressure steam.

[0015] Specifically, the concentration device includes a nitric acid concentration device and a sulfuric acid concentration device. The nitric acid concentration device includes a nitric acid concentration kettle and a nitric acid concentration tower. The sulfuric acid concentration device includes a sulfuric acid concentration kettle and a washing tower. The stop of supplying high-temperature steam to the waste acid treatment system is achieved by closing the steam valve, such as installing a steam valve at the high-temperature steam inlet of the concentration device.

[0016] In order to achieve automatic control, therefore, a DCS control system is introduced. The DCS control system is respectively connected to the steam valve, the pressure sensor and the three-way valve. The DCS control system controls the opening and closing of the steam valve and the flow direction of the three-way valve according to the pressure data of the pressure sensor, that is, when the pressure inside the concentration device does not exceed the preset value, the waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port and the three-way valve. When the pressure inside the concentration device exceeds the preset value, the supply of high-temperature steam to the waste acid treatment system is stopped, such as closing the steam valve at the high-temperature steam inlet of the concentration device, and the three-way valve is switched, so that the gas in the waste acid treatment system passes through the pneumatic three-way valve and then flows to the waste water collection tank after being absorbed by the low-pressure steam.

[0017] An embodiment of the present invention, as attached Figure 1 As described, a steam valve, a pressure sensor, a three-way valve, an ejector, a waste water collection tank and a DCS control system are added to the existing waste acid treatment system. The steam valve is installed at the high-temperature steam inlet of the nitric acid concentration kettle. The pressure sensor is used to detect the pressure inside the nitric acid concentration kettle. The three-way valve is installed between the waste acid treatment system and the waste gas absorption system, and a branch is led out to be connected to a fluid inlet of the ejector. The other fluid inlet of the ejector is connected to low-pressure steam, and the outlet of the ejector extends below the sealed liquid level of the waste water collection tank.

[0018] Working principle during the operation of the waste acid treatment system: The pressure sensor continuously detects the pressure inside the nitric acid concentration kettle and transmits the pressure to the DCS control system. The DCS control system executes the following logic: When the pressure inside the nitric acid concentration kettle is within the preset value, the waste gas generated by the waste acid treatment system flows through the three-way valve to the waste gas absorption system. When the pressure inside the concentration device exceeds the preset value, the DCS control system controls the steam valve to close and switches the three-way valve, so that the gas in the waste acid treatment system passes through the pneumatic three-way valve and then flows to the wastewater collection tank after being absorbed by the low-pressure steam.

[0019] Specifically, the preset value is determined by the performance of the nitric acid concentration kettle, such as 96 Kpa. The safety interlock protection device of the waste acid treatment system includes a UPS power supply, which does not affect the normal operation of the safety interlock protection device of the waste acid treatment system when the mains power is cut off.

[0020] In addition, the calculation formula for the height h at which the outlet of the ejector extends below the sealed liquid level of the wastewater collection tank is: h = (P1 - Pa) / ρg, where h represents the height, P1 represents the exhaust pressure at the outlet of the ejector, Pa represents the standard atmospheric pressure, ρ represents the density of water, and g represents the acceleration due to gravity. Thus, the range of h can be determined according to the depth of the wastewater collection tank, and then the exhaust pressure at the outlet of the ejector can be calculated. Based on the premise that the wastewater in the wastewater collection tank does not flow back into the ejector, the pressure range of the low-pressure steam can be deduced. To prevent the waste gas from escaping everywhere, a rain shower device is also installed in the wastewater collection tank to absorb the acid smoke in the waste gas.

Claims

1. Safety interlock protection device for waste acid treatment system, the waste acid treatment system includes a concentration device, vacuum heating the concentration device by high-temperature steam, treating waste acid by distillation and concentration method, and the waste gas generated by the waste acid treatment system flows to the waste gas absorption system through the exhaust port; characterized in that, It includes a DCS control system, a steam valve, a pressure sensor, a three-way valve, an ejector, and a wastewater collection tank; The pressure sensor is connected to the concentration device and is used to detect the pressure inside the concentration device; The first end of the three-way valve is connected to the exhaust port of the waste acid treatment system, the second end is connected to the waste gas absorption system, the third end is connected to a fluid inlet of the ejector, the other fluid inlet of the ejector is connected to low-pressure steam, and the outlet of the ejector extends below the sealed liquid level of the wastewater collection tank; The DCS control system is respectively connected to the steam valve, the pressure sensor, and the three-way valve. The DCS control system controls the opening and closing of the steam valve and switches the flow direction of the three-way valve according to the pressure data of the pressure sensor: When the pressure inside the concentration device does not exceed the preset value, the waste gas generated by the waste acid treatment system flows through the exhaust port and the three-way valve to the waste gas absorption system; When the pressure inside the concentration device exceeds the preset value, the steam valve is closed to stop providing high-temperature steam to the waste acid treatment system, and the three-way valve is switched so that the gas in the waste acid treatment system passes through the three-way valve and then flows to the wastewater collection tank after being absorbed by the low-pressure steam.

2. The safety interlock protection device of the waste acid treatment system according to claim 1, characterized in that, The concentration device includes a nitric acid concentration device and a sulfuric acid concentration device.

3. The safety interlock protection device of the waste acid treatment system according to claim 2, wherein, The nitric acid concentration device includes a nitric acid concentration kettle and a nitric acid concentration tower.

4. The safety interlock protection device of the waste acid treatment system according to claim 2, characterized in that, The sulfuric acid concentration device includes a sulfuric acid concentration kettle and a washing tower.

5. The safety interlock protection device of the waste acid treatment system according to claim 1, characterized in that, Stopping providing high-temperature steam to the waste acid treatment system is achieved by closing the steam valve.

6. The safety interlock protection device of the waste acid treatment system according to any one of claims 1-5, characterized in that, The calculation formula for the height h at which the outlet of the ejector extends below the sealed liquid level of the wastewater collection tank is: h = (P1 - Pa) / ρg, where h represents the height, P1 represents the exhaust pressure at the outlet of the ejector, Pa represents the standard atmospheric pressure, ρ represents the density of water, and g represents the acceleration due to gravity.

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