—————  ◆ Industrial exhaust gas analysis ◆ —————  

>> Source of acid mist exhaust gas

There are two main mechanisms for the formation of acid mist:
   

 (1) The surface of the acid solution evaporates, acid molecules enter the air, and condensate with the water in the air to form mist droplets;

 (2) There is a chemical reaction in the acid solution, the bubbles form and float on the liquid surface, and then explode, bringing out the droplets.

 (3) In addition, the accompanying acid mist emission process will inevitably have the emission of molecular acidic gaseous pollutants such as SO2 and NOX, so the emission process and the composition of the emissions are relatively complicated.

>> Acid mist exhaust gas composition

There are several common gases that can form acid mist:
   

 (1) Hydrogen halide (HX) is a colorless, irritating odor gas, easily soluble in water, and the aqueous solution is acid (hydrohalic acid), which is volatile and easy to form acid mist.

 (2) The combination of sulfur dioxide and water vapor can easily form acid mist.

 (3) SO3 is easily absorbed by water. If high temperature, it is easy to form acid mist with water vapor.

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>> Design Principles

(1) Assist enterprises to adopt scientific and reasonable collection methods, and reduce gas volume as much as possible on the premise of achieving the collection effect.

(2) Actively and steadily adopt new technologies and new equipment, and adopt advanced and reliable pollution control technology in accordance with the status quo and management level of the enterprise, and strive to achieve stable operation, low cost, convenient management, and easy maintenance, so as to completely eliminate exhaust gas pollution and protect Environmental purpose. (2015-01-01)

(3) Properly resolve the pollutants generated during the construction and operation of the project to avoid secondary pollution.

(4) Strictly implement current national, local, and other codes, regulations, and standards on fire prevention, safety, health, and environmental protection.

(5) Select new, high-efficiency, low-noise equipment, pay attention to energy saving and consumption reduction.

(6) The overall plan layout strives to be compact, reasonably smooth, simple and practical. Minimize project occupation and construction difficulty.

(7) Strictly implement relevant national design codes and standards, and pay attention to fire protection and safety work. (GB16297-1996)

(8) Control industrial pollution in accordance with relevant national and local environmental protection laws, regulations and industrial policy requirements, and give full play to the social, environmental and economic benefits of construction projects.

>> Project scope and standards

1. Project scope  

(1) The designer is responsible for the design, manufacture, installation, commissioning of the exhaust gas treatment equipment, and the design of the relevant pipelines.

(2) The designer is responsible for training the equipment operator of the owner unit.

(3) The owner unit is responsible for the supporting public works of the project, including power supply, water vapor, compressed air, circulating cooling water, etc.

2.Technical requirements

(1) The project does not consider land acquisition and uses the original factory land, which cannot seriously affect production;

(2) Adopt mature exhaust gas treatment technology, which requires technology to be safe, reliable, and economically reasonable;

(3) The disposal of by-products should not cause secondary pollution;

(4) All equipment and materials are new;

(5) Simple observation, monitoring and maintenance;

(6) Ensure personnel and equipment safety;

(7) Save energy, water and raw materials;

>> Emission Standard

The acid mist exhaust gas emission standard implements the Comprehensive Air Pollutant Emission Standard (GB16297-1996). The implementation standards are as follows:

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(1) Project-related information provided by the owner

(2) Environmental Protection Law of the People's Republic of China (2015-01-01)

(3) Law of the People's Republic of China on the Prevention and Control of Atmospheric Pollution (2016-01-01)

(4) Ambient air quality standard (GB3095-2012)

(5) Decree No. 72 of the President of the People's Republic of China on the Law of the People's Republic of China on Cleaner Production Promotion

(6) "National 13th Five-Year Plan"

(7) "Integrated Emission Standard of Air Pollutants" (GB16297-1996)

(8) Emission Standard of Odor Pollutants (GB14554-1993)

(9) "Code for Environmental Protection Design of Construction Projects" (GB50483-2009)

(10) Design Code for Heating Ventilation and Air Conditioning (GB50019-2003)

(11) Code for Fire Protection of Building Design (GB50016-2014)

(12) Design Specification for Power Supply and Distribution System (GB50052-2009)

(13) "Control Standards for Emissions of Volatile Organic Compounds in Industrial Enterprises" DB13 / 2322-2016

(14) Guangzhou Puhua Environmental Technology Co., Ltd.'s comprehensive experience based on years of exhaust gas treatment project engineering and technology research and development

———————————————  ◆ Exhaust gas system design ◆ ——————————————     

>> Acid mist exhaust gas treatment process

Considering the operating cost and safety of the acid mist exhaust gas to be treated , nitric acid, sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, hydrosulfuric acid and other acid mist exhaust gas purification schemes are similar, and all adopt the process of absorption and recycling: exhaust gas source → 1-level acid mist absorption tower → Level 2 acid mist absorption tower → Discharge up to standard. The process route diagram is as follows:

Exhaust gas source → demister → purification tower → core purification module → induced draft fan → deep purification 

>> Introduction of acid mist exhaust gas treatment process

(1) System composition of process flow: It consists of exhaust gas collection system, air induction system, exhaust gas purification system, and exhaust system.

(2) The exhaust gas has entered the first and second acid mist exhaust gas purification towers. The alkaline scrubbing liquid in the absorption tower is pumped by the circulating pump to the tower and flows downward through the packing. The acid mist exhaust gas rises countercurrently, and the wet surface of the packing comes into contact with gas and liquid. A series of physical and chemical reactions occur, and due to the concentration difference, the Quality process, thus completing the purification process of the gas, the purified exhaust gas is dehydrated and discharged by a centrifugal fan after reaching the standard. The circulating fluid is regularly discharged to the sewage treatment station.

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