Formic acid vent gas purification and recovery treatment device

Abstract

The utility model provides a kind of formic acid venting tail gas purification recycling processing device, including washing absorption tower, washing absorption tower is provided with tail gas inlet pipe, top setting gas phase outlet pipe, it is characterized by: washing absorption tower's gas phase outlet pipe is sequentially communicated tail gas cooler, demister, dryer and compressor, tail gas is washed, condensed, dewatered and pressurized after being introduced into carbonyl system.The utility model has beneficial effect in that: it solves the formic acid industry venting tail gas processing problem.By selecting a kind of washing absorption liquid, after washing tower, using efficient filler, the formic acid in venting tail gas is washed and neutralized and absorbed, after absorption, venting air is cooled, demisted, dried to obtain clean venting tail gas without formic acid and low dew point, realize environmental protection standard discharge, and the formic acid potassium solution produced after absorption and neutralization can be recycled to potassium salt evaporation system to realize resource utilization.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically to a formic acid venting tail gas purification and recovery treatment device. Background Technology

[0002] The vent gas emitted from the distillation column (commonly known as the dicarboxylic acid column) in the distillation unit of the diacid production plant has extremely high resource value. Its core component, carbon monoxide (CO), maintains a stable high purity level of ≥98%, and the flow rate reaches 1000 standard cubic meters per hour (Nm³ / h). If such high-grade, high-flow-rate carbon-rich gas can be effectively recovered, it can theoretically serve as a high-quality raw material for the carbonyl synthesis process, significantly reducing production costs and carbon emissions. However, the persistent trace amounts of formic acid (HCOOH) impurities and saturated water vapor in this vent gas pose a significant technical obstacle. Formic acid is highly corrosive, and its direct entry into the carbonyl synthesis system will cause electrochemical corrosion of critical equipment such as reactors, heat exchangers, and pipelines, significantly shortening equipment lifespan and increasing the risk of leakage. At the same time, the accompanying water vapor, after entering the high-pressure carbonyl reaction environment, will not only dilute the concentration of reactants but also accelerate the hydroxylation deactivation process of precious metal catalysts, leading to an abnormal increase in catalyst consumption and a substantial increase in production and operating costs.

[0003] Due to the aforementioned technological limitations, existing treatment methods have been forced to abandon the resource utilization path of exhaust gas and instead adopt a water washing-incineration disposal mode: firstly, most of the formic acid and water-soluble components in the exhaust gas are removed by washing in a water spray tower, and then the washed gas is transported to a coal-fired boiler for high-temperature incineration. Although this process can avoid direct damage to the carbonyl system, it generates new systemic risks: while the water washing process can remove some formic acid, the low-concentration formic acid solution generated makes the exhaust gas highly acidic, with a pH usually below 3.0. Such moist acidic gas can cause severe acid dew point corrosion to carbon steel pipes, valves, and boiler burners during transportation. More seriously, the acidic gases produced by the decomposition of formic acid during incineration and the unburned hydrocarbons may generate toxic pollutants such as dioxins under certain operating conditions. In addition, the emission of acidic flue gas significantly aggravates the corrosion of the tail flue and the burden on the desulfurization system, making the entire disposal chain face multiple risks of equipment integrity damage and exceeding environmental emission standards, essentially turning high-value resources into potential sources of environmental responsibility. Utility Model Content

[0004] This invention addresses the problem that formic acid venting exhaust gas, being a moist acidic gas, causes severe acid dew point corrosion to carbon steel pipes, valves, and boiler burners during transportation.

[0005] A formic acid venting tail gas purification and recovery treatment device is provided, including a scrubbing absorption tower. The scrubbing absorption tower is provided with a tail gas inlet pipe and a gas phase outlet pipe at the top. The gas phase outlet pipe of the scrubbing absorption tower is connected in sequence to a tail gas cooler, a demister, a dryer and a compressor. The tail gas is fed into a carbonyl system after being scrubbed, condensed, dehydrated and pressurized.

[0006] As a preferred embodiment, the bottom of the washing absorption tower is provided with a liquid phase outlet pipe that is connected in parallel to the washing water cooler and the liquid phase vent pipe, and the outlet pipe of the washing water cooler is connected to the washing absorption tower.

[0007] As a preferred embodiment, the liquid phase outlet pipe is equipped with a washing water circulation pump.

[0008] As a preferred embodiment, the exhaust gas inlet pipe is equipped with an inlet buffer tank.

[0009] As a preferred embodiment, a gas venting pipe is provided between the exhaust gas cooler and the demister, and a moisture content sensor is provided between the dryer and the compressor. The moisture content sensor is connected to the valve of the gas venting pipe and the valve of the demister to control the valve opening and closing.

[0010] As a preferred embodiment, the washing absorption tower is equipped with a level gauge electrically connected to a valve of the liquid phase venting pipeline and a washing water circulation pump.

[0011] As a preferred embodiment, the gas phase outlet pipe is equipped with a flow sensor electrically connected to the valve of the exhaust gas inlet pipe.

[0012] The beneficial effects of this utility model are as follows:

[0013] This invention solves the problem of vent gas treatment in the formic acid industry by independently developing and designing a vent gas washing, absorption, cooling, and drying treatment facility for primary and secondary acid towers. By selecting a washing and absorption liquid, the vent gas passes through a washing tower using high-efficiency packing to wash, neutralize, and absorb the formic acid. The absorbed vent gas is then cooled, demisted, and dried to obtain clean vent gas free of formic acid and with a low dew point, mainly containing carbon monoxide. This gas is then transported to a carbonyl system for recycling via a compressor system, achieving environmentally compliant emissions. Furthermore, the potassium formate solution produced after absorption and neutralization can be recycled to a potassium salt evaporation system for resource utilization. The system recovers 1000 Nm³ / h of high-purity (≥98%) CO vent gas annually, generating approximately 10 million RMB in economic benefits per year. Attached Figure Description

[0014] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0015] Figure 1 This is a schematic diagram of the structure of this utility model.

[0016] The numbers in the attached diagram are:

[0017] 1. Imported buffer tank; 2. Washing water circulation pump; 3. Washing absorption tower; 31. Tail gas inlet pipe; 32. Gas phase outlet pipe; 33. Liquid phase outlet pipe; 34. Flow sensor; 35. Liquid level gauge; 4. Washing water cooler; 5. Tail gas cooler; 6. Demister; 7. Dryer; 8. Compressor. Detailed Implementation

[0018] To illustrate the features of this utility model, the following description, in conjunction with the accompanying drawings and embodiments, will further explain this utility model.

[0019] Example:

[0020] Please see Figure 1 This embodiment provides a formic acid venting tail gas purification and recovery treatment device. Specifically, the washing absorption tower 3 has a tail gas inlet pipe 31 at its bottom for introducing the formic acid venting tail gas to be treated. An inlet buffer tank 1 is installed on the tail gas inlet pipe 31 to stabilize the airflow. The washing absorption tower 3 has a gas phase outlet pipe 32 at its top for discharging the pre-purified tail gas. The gas phase outlet pipe 32 is also equipped with a flow sensor 34, which is electrically connected to a valve on the tail gas inlet pipe 31 to monitor and adjust the inlet flow rate.

[0021] The gas phase outlet pipe 32 of the scrubbing absorption tower 3 is sequentially connected to the tail gas cooler 5, demister 6, dryer 7, and compressor 8. The tail gas treated by the scrubbing absorption tower 3 flows sequentially through the tail gas cooler 5 for condensation and cooling, enters the demister 6 to remove entrained droplets, then passes through the dryer 7 for deep dehydration, and finally is pressurized by the compressor 8 and delivered to the carbonyl system. A gas phase vent pipe is installed on the connecting pipe between the tail gas cooler 5 and the demister 6 for emergency or necessary gas discharge.

[0022] A liquid phase outlet pipe 33 is installed at the bottom of the washing absorption tower 3. The liquid phase outlet pipe 33 connects to two parallel paths: one is a liquid phase vent pipe for discharging waste liquid; the other connects to the inlet of the washing water cooler 4. A washing water circulation pump 2 is installed on the liquid phase outlet pipe 33 to drive the washing liquid circulation. The outlet pipe of the washing water cooler 4 connects back to the washing absorption tower 3, forming a circulating cooling loop for the washing liquid. A level gauge 35 is installed on the washing absorption tower 3. This level gauge 35 is electrically connected to a valve on the liquid phase vent pipe and the washing water circulation pump 2, and is used to automatically control waste liquid discharge and the start / stop of the circulation pump based on the liquid level inside the tower.

[0023] In summary, this device, through the washing absorption tower 3, washing water cooler 4, tail gas cooler 5, demister 6, dryer 7, compressor 8 and their connecting pipes and valves, along with components such as the inlet buffer tank 1, flow sensor 34, washing water circulation pump 2, and level gauge 35, achieves a complete treatment process for the purification, condensate and droplet removal, deep drying, pressurization of formic acid venting tail gas, and ultimately its recovery to the carbonyl system.

[0024] The above embodiments and accompanying drawings are only used to illustrate the technical solutions of this utility model and are not intended to limit this utility model. This utility model has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of this utility model do not depart from the spirit of this utility model and should also fall within the protection scope of the claims of this utility model. Other related technical structures not disclosed in detail in this utility model are existing technologies in the art.

Claims

1. A formic acid vent gas purification and recovery treatment device, comprising a washing absorption tower (3), the washing absorption tower (3) is provided with a tail gas inlet pipe (31), and a gas phase outlet pipe (32) is arranged at the top, characterized in that: The gas phase outlet pipe (32) of the washing absorption tower (3) is connected with the tail gas cooler (5), the mist eliminator (6), the dryer (7) and the compressor (8) in sequence, and the tail gas is introduced into the carbonyl system after washing, condensation, dehydration and pressure increase.

2. The formic acid purge off-gas purification and recovery treatment device according to claim 1, characterized by: The bottom of the washing absorption tower (3) is provided with a liquid phase outlet pipe (33) connected with the washing water cooler (4) and a liquid phase vent pipe in parallel, and the outlet pipe of the washing water cooler (4) is connected with the washing absorption tower (3).

3. The apparatus for purifying and recovering a formic acid purge tail gas according to claim 2, characterized by: The liquid phase outlet pipe (33) is provided with a washing water circulating pump (2).

4. The formic acid purge off-gas purification and recovery treatment device according to claim 1, characterized by: The tail gas inlet pipe (31) is provided with an inlet buffer tank (1).

5. The formic acid purge off-gas purification and recovery treatment device according to claim 1, characterized by: A gas phase vent pipe is arranged between the tail gas cooler (5) and the mist eliminator (6), a water content sensor is arranged between the dryer (7) and the compressor (8), and the water content sensor is connected with the valve of the gas phase vent pipe and the valve of the mist eliminator (6) to control the opening and closing of the valves.

6. The formic acid purge off-gas purification and recovery treatment device according to claim 2, characterized by: The washing absorption tower (3) is provided with a liquid level meter (35) electrically connected with the valve of the liquid phase vent pipe and the washing water circulating pump (2).

7. The formic acid purge off-gas purification and recovery treatment device according to claim 1, characterized by: The gas phase outlet pipe (32) is provided with a flow sensor (34) electrically connected with the valve of the tail gas inlet pipe (31).

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