About The Exhaust Gas Treatment Process In Pharmaceutical Workshops

Pharmaceutical workshops often produce certain waste gases, including smoke, dust particles, and organic waste gases. For dust, dust and other particles, mechanical dust removal, washing dust removal, filter dust removal, electrostatic dust removal and other processes can be used. For organic waste gas, processes such as absorption, adsorption, condensation, incineration, biological treatment, photocatalytic oxidation, and low-temperature plasma purification can be used. In practice, in order to improve the removal efficiency and reduce the treatment cost, multiple processes can be combined.

Pharmaceuticals are a key industry in society and are related to national health. Since the 21st century, the domestic pharmaceutical industry has developed rapidly, which has brought protection to the people’s livelihood, but the pollution generated in the manufacturing process has inevitably brought pressure to the environment. Pharmaceutical processes include fermentation, chemical synthesis, bioengineering, extraction, etc., all of which may generate a certain amount of waste gas, pollute the atmospheric environment, threaten the ecology, and endanger human health. Under the background that the central and local governments are gradually strengthening environmental protection and governance, pharmaceutical companies have also become the focus of relevant departments. For this reason, it is very necessary to sort out and summarize the treatment process of organic waste gas in the pharmaceutical process.

Part 1 Exhaust Gas And Its Hazards In Pharmaceutical Workshops

In order to achieve a given drug effect, the ingredients of the drug are complex, and these ingredients need to be combined in a certain way, which determines that drug manufacturing is a complicated process, and it is inevitable to generate various waste gases, especially organic exhaust gas.

(1) Sulfur-containing compounds can further produce hydrogen sulfide and sulfur dioxide, and even produce sulfur trioxide, sulfuric acid and other sulfate radical compounds.

(2) Nitrogen-containing compounds can regenerate nitric oxide, nitrogen dioxide, and even nitric acid, nitric acid compounds, and ozone.

(3) Hydrocarbons, further generating carbon monoxide and carbon dioxide.

(4) Hydrocarbons are easy to form volatile organic compound complexes and regenerate aldehydes and ketones.

(5) Halogen compounds can further generate pollutants such as hydrogen chloride and hydrogen fluoride.

(6) Inorganic particulate matter, mainly dust and smoke generated after crushing, grinding, screening, incineration and other processes. On the other hand, because a large amount of volatile organic solvents such as ethyl acetate, acetone, benzene, alcohols, butyl acetate, etc. are used in the processing process, VOCs pollution will also be generated.

It can be seen that the waste gas generated in the pharmaceutical process is not only complex in composition and diverse in type, but also has a large amount and flow rate of waste gas, making it difficult to deal with. Many pollutants in pharmaceutical waste gas have certain pollution, which will cause harm to the environment and human body. Part of the particulate matter in it is dust and smoke, which will damage human eyes, nasal cavity, pharynx, lungs and other organs, and will also carry certain harmful microorganisms; too high a concentration of carbon monoxide will cause human poisoning; nitrogen oxides will damage various organs of the human body , corrode human skin; sulfur oxides irritate the eyes and can cause cancer; VOCs are mostly toxic, and some have carcinogenic ability, which can damage the liver, kidneys, circulatory system, reproductive system, etc. And these pollutants have the “capacity” to destroy the ozone layer, corrode surrounding buildings and other infrastructure, endanger animals and plants and destroy the ecosystem, and are flammable and explosive, which are extremely harmful.

Part 2 Particulate Waste Gas Treatment Process In Pharmaceutical Workshop

Smoke and dust generated in the pharmaceutical process can generally be eliminated by means of machinery, washing, filtration, and static electricity.

2.1 Mechanical Dust Removal Process

This method is mainly based on the physical properties of exhaust gas particles, through mechanical intervention, so that they are gradually separated based on inertia, centrifugal force and gravity after a certain movement or balance. Among them, the gravity settling chamber is to set a pipe for the passage of smoke and dust on the top, and leave sufficient time in the middle position, and set corresponding upper and lower obstacles, so that the dust and smoke will fall to the device below by its own gravity, without smoke and dust. The relatively clean gas of dust flows out through the pipe opening on the other side. The inertial dust collector gives the dusty gas a large downward thrust, making it move forward in a fixed direction, and then turns sharply above the dust collection basket, so that the air can turn and flow away, while the dust and smoke can be retained by inertia In the basket, the air is purified as much as possible. The cyclone dust collector is a device with a three-dimensional cone. After the dusty gas enters, it is rotated. The smoke and dust are gradually separated to the bottom due to centrifugal force, while the purified air rises in the middle and is discharged.

2.2 Washing And Dust Removal Process

For the particulate matter existing in the exhaust gas, it can also be eliminated by washing. The specific method is to use pure water or a liquid with a certain washing function to let the exhaust gas pass through the liquid, and the particles can then combine with the liquid, and the clean air can overflow from the water, so that the air can be purified. . In order to improve the removal efficiency, the liquid substance can also be formed into a film, which makes the passage of exhaust gas easier and faster. This method of dust removal by means of water is also called wet method. In practice, a spray scrubber is used as the basic installation. Under normal pressure and gas input rate, the removal efficiency can reach 80%. To improve this efficiency, methods such as increasing the pressure can be used.

2.3 Filtration And Dust Removal Process

For the smoke and dust particles in the exhaust gas, it can also be retained by filtering. Because of the smaller size of particulate matter, smaller filter membranes are required to successfully filter them. Generally speaking, the diameter of dust particles produced in pharmaceutical workshops is about 60 μm, which requires the pore size of the filter membrane to be about 10 μm. Relevant studies have shown that the filtration method has a better dust removal effect while reducing the wind speed. Increasing the thickness of the particle layer can improve the effect of dust removal. As the filtration works, dust and soot particles will accumulate on one side of the filter membrane, which needs to be further removed for repeated use. In practice, the filtration and mechanical processes can also be combined, so that the smoke and dust particles can be separated first, and then pass through the filter membrane, so that the air purification effect is better, and the dust and smoke removal rate can reach 99%.

2.4 Electrostatic Precipitator Process

For dust and smoke particles, a high-voltage electrostatic field can be used to adsorb them to the positive and negative poles, thereby realizing the purification of exhaust gas. In practice, this process is more suitable for the treatment of soot, because the strong electric field can adsorb ions more accurately, making the removal rate as high as 99%. However, the removal effect of this method is not good for dust particles. Therefore, it is often seen that such equipment is installed above the chimneys of some pharmaceutical factories, and the exhausted smoke is directly passed through a strong electric field, and the smoke is directly discharged into the air after being better treated.

Part 3 Organic Waste Gas Treatment Process In Pharmaceutical Workshop

In addition to tiny particles such as dust and smoke, pharmaceutical workshops will also release certain organic waste gas. The treatment processes that can be used include absorption, adsorption, condensation, combustion, biological treatment, photocatalytic oxidation, plasma purification, etc.

3.1 Absorption Process

This method refers to the absorption of organic waste gas through a certain solution, so that the pollutants are retained in the liquid, and the clean air can be released. This method of treating organic waste gas is similar to the principle of using a washing process to remove dust and smoke. The difference is that this method not only dissolves organic pollutants in water, but also reacts them with chemical substances in the liquid to generate other harmless substances. Generally speaking, alkaline substances such as sodium hydroxide, sodium carbonate, lime, and ammonia water are used as solvents in the absorption liquid, or sulfuric acid and hydrochloric acid are used as solvents, and even simple fats, ethers, and ketones are used as solvents. Absorb and dissolve various organic waste gases. Generally speaking, the organic waste gas treatment efficiency brought by this method can reach more than 95%.

3.2 Adsorption Process

The principle of the adsorption process is to use some materials with adsorption capacity to adsorb pollutants on the surface, so that they can be concentrated and further processed. At present, common adsorption materials include activated carbon, molecular sieve, zeolite, diatomaceous earth, silica gel, activated alumina, etc. The adsorption process determines that it requires more materials to adsorb a certain range of pollutants, that is, it is difficult to treat a large number of pollutants quickly at the same time. Based on its good treatment capacity and insufficient treatment capacity, it is suitable for the treatment of some pollutants with high toxicity but low concentration. After adsorption, it can be rewet recovered, incinerated, etc. According to relevant research results, it is found that using activated carbon as an adsorption material and giving sufficient contact time can absorb more than 95% of pollutants. Because these materials need to be replaced, whether it is the labor required for replacement or the material itself, more costs will be required.

3.3 Condensation Process

Using the principle of different freezing points of different air components, the organic waste gas is cooled and pressurized, so that the organic waste gas can be separated from the air. Because the condensation technology is used, it is called the condensation method. In practice, cooling liquid is needed. If it needs to contact cooling liquid, it is called contact condensation process. If it does not need to contact condensate, it is called surface contact condensation process, which relies on cooling walls to conduct heat. The advantage of using this process is that the treated waste gas can obtain a single substance according to different condensation points, so it has a high purity and can be recycled.

3.4 Combustion Purification Process

Most of the substances contained in organic waste gas are mainly carbon, hydrogen, and oxygen. These organic substances usually produce harmless water and carbon dioxide after combustion. It can be seen that the use of incineration technology can easily remove organic pollutants. In practice, direct incineration, thermal incineration and catalytic incineration can be used in three ways. Among them, direct incineration refers to using other fire sources to directly heat the exhaust gas to the ignition point, and incineration reaction with oxygen, which is suitable for some exhaust gases with relatively high density, that is, the density is high enough to be directly incinerated; thermal incineration refers to continuous combustion through other heating means. Heating the gas so that it reacts with oxygen at a higher temperature environment does not necessarily burn itself, which is suitable for some waste gases with low density; catalytic combustion refers to using a catalyst to place the waste gas at about 300 °C Temperature, so that it reacts with oxygen to form water and carbon dioxide. Relatively speaking, catalytic combustion is safer and does not require too high a temperature, but the disadvantage is that the catalyst is often toxic.

In actual exploration, the regenerative incinerator can be used to carry out direct incineration, which can provide high temperature conditions for the combustion of organic waste gas. The heat energy released by this incineration can also be absorbed by the heat storage body, and then provide for the subsequent organic waste gas. The heat kept it burning. This kind of device has high processing efficiency and can also process a lot of waste gas at one time, but the disadvantage is that the cost is high and a large initial investment is required. In order to incinerate exhaust gases with different characteristics, it is also possible to combine direct incineration with thermal incineration, combining different time periods or different incineration spaces. In fact, simple incineration does not necessarily eliminate all pollutants in the exhaust gas. Therefore, the air after incineration can also be washed. Because of the higher temperature of this washing, spray the corresponding Liquids such as water work better. Combining incineration and washing, the removal rate can reach more than 99%.

3.5 Biological Treatment Process

Biological metabolism has the effect of “turning decay into magic”, which can absorb some pollutants and generate other harmless substances through the internal biological operation. Among them, microorganisms have become the best choice for dealing with various pollutants because of their rapid reproduction, high bioenergy, and directional cultivation. For organic waste gas, there are a variety of biological treatment methods. First, the wet absorption method is used to dissolve the pollutants into the water body, and then the microorganisms are cultivated in the water body to decompose the pollutants. This is called the biological absorption method. Adsorbing microorganisms on solid filter materials and directly contacting organic waste gas to allow pollutants to be adsorbed and treated is called biological filtration.

Relatively speaking, the biological absorption method fixes the pollutants in the water body, which can have sufficient time to decompose, which is safer, while the biological filtration method is not efficient because of the fluidity of the gas. According to the technical principle, it can be seen that the method of microbial degradation of waste water and waste gas has obvious advantages, has high safety, and purifies pollutants thoroughly, and does not require too high operation and maintenance costs after the one-time investment. But there are also certain disadvantages, including a large footprint and biomes that need to be dealt with. In recent years, the academic circle has studied some other biological treatment processes, including biological filter, biological washing, biological trickling and so on. Among them, the biological filter is composed of water pump, blower, biological filler, air supply pipeline, filter tank, etc.; the biological scrubber includes biological washing tank, regeneration reaction tank, water pump and other components; Liquid and other components.

In practice, the two methods of biological washing and biological trickling can be combined, and the water body that has absorbed organic waste gas can be used as circulating water, and certain fillers can be placed in the washing tower and biochemical tower to cultivate microorganisms that decompose pollutants in a directional way. Pollutants can be reduced by 90% in a week.

3.6 Photocatalytic Oxidation Process

This process was invented in recent years. It decomposes organic waste gas into harmless water and carbon dioxide based on the strong oxidizing hydroxyl radicals and negative oxygen ions generated by semiconductor photocatalysts driven by light of a certain wavelength. The most effective material in practice is titanium dioxide, because it is non-toxic and widely exists in nature, and the cost of obtaining it is relatively low. At the same time, it can be used as a catalyst without too harsh conditions, and the effect is more in line with expectations. There is a process called multi-stage ozone photocatalysis, which covers three processes of ultraviolet photolysis, ozone oxidation, and ozone catalytic oxidation. It requires blowers, activated carbon adsorption beds, air pumps, ozone photocatalytic towers and other components. From the blower through the air pump into the activated carbon adsorption bed, after adsorption, it is photolyzed by ultraviolet light, and then introduced into the ozone photocatalytic tower for ozone oxidation and catalytic oxidation, and finally clean gas is obtained. Using this process, the removal rate of organic waste gas in pharmaceutical workshops can reach 85%.

3.7 Low Temperature Plasma Purification Process

This technology takes advantage of the characteristics of the plasma state of matter. Its technical idea is that in addition to the solid-liquid-gas three-phase, the object also has a plasma state, which is an unstable state in which a substance is ionized in a gaseous state. Molecular states are partially broken to form electrons, ions, atoms and free radicals. For organic waste gas, there will be certain hydroxide ions, ozone, etc. in this form. The plasma state is that the number of positive and negative charges in these ions is equal. A high-voltage electric field is applied to the organic waste gas, so that electrons impact the organic waste gas molecules at high speed, so that they form a plasma state at low temperature, and thus generate small molecular harmless substances. In practice, the treatment of exhaust gas will use pulsed corona discharge or dielectric barrier discharge, which can be carried out under normal pressure.

Part 4 Conclusion

Due to the complex pharmaceutical process, various types of polluting waste gas will be produced in the pharmaceutical workshop, including granular dust and smoke, as well as some organic pollutants. These pollutants can be eliminated in a variety of ways, and in order to better improve the removal effect and reduce the treatment cost, a variety of treatment methods should be combined, and active innovations should be made in the fields of bioengineering and catalysts.