The amount of compressed air used in the chemical process covers many aspects and needs to be calculated comprehensively according to the specific process flow, equipment requirements and production scale. Its core components include gas consumption for process, gas consumption for equipment driving, gas consumption for instrument control, gas consumption for purging and cleaning, gas consumption for safety and emergency the following is a specific analysis:
1. Gas consumption for process
refers to the compressed air demand that is directly involved in chemical reactions, material transportation or process control, and is the core gas part of chemical production.
- Typical Scene:
- pneumatic conveying conveying powdery or granular materials with compressed air (such as cement, plastic particles, catalyst), the gas consumption shall be calculated according to the conveying distance, material density and conveying speed.
- chemical reaction gas supply: Provide oxidant for gas-solid or gas-liquid reaction (such as sulfuric acid production by air oxidation method), inert gas protection (such as polymerization reaction under nitrogen protection, degreasing and dehumidification if compressed air is used) or stirring gas (such as fermentation tank ventilation).
- Drying and Dehydration: Purge the surface moisture of materials with compressed air (such as the drying process of chemical products), which shall be calculated according to the water content of materials, drying time and air flow rate.
- Calculation Points: It needs to be determined in combination with process parameters (such as reaction rate, conveying capacity, drying efficiency) and equipment specifications (such as conveying pipe diameter, reactor volume).
2. Gas consumption for equipment driving
refers to the compressed air required to drive pneumatic equipment (such as valves, pumps, agitators), which is the key to ensure the normal operation of the equipment.
- Typical Scene:
- pneumatic valve: To control the on-off or flow regulation of fluid in the pipeline, the gas consumption shall be calculated according to the number of valves, switching frequency and action time.
- pneumatic pump: The transportation of liquid or gas (such as chemical raw material pump, vacuum pump) shall be calculated according to the displacement, working pressure and running time of the pump.
- Pneumatic agitator: Stirring materials in the reaction kettle or storage tank shall be calculated according to the power, speed and medium viscosity of the stirrer.
- Calculation Points: It is necessary to refer to the air consumption parameters provided by the equipment manufacturer (such as air consumption per minute) and comprehensively calculate it in combination with the running time of the equipment.
3. Gas consumption for instrument control
refers to the compressed air that provides the power source for pneumatic instruments (such as pressure transmitters, flow meters, and regulating valves) to ensure precise control of process parameters.
- Typical Scene:
- pressure control pneumatic pressure transmitter monitors pipeline or equipment pressure and requires stable air supply support.
- Flow regulation pneumatic control valve adjusts the fluid flow according to the process requirements, and requires continuous gas supply.
- Temperature control: Pneumatic actuator drives cooling water valve or steam valve to maintain stable reaction temperature.
- Calculation Points: The gas consumption of the instrument is usually small, but it is necessary to consider the simultaneous use factor (such as the peak demand when multiple instruments operate at the same time) and reserve a certain margin.
4. Gas consumption for purging and cleaning
refers to the use of compressed air to purge pipelines, equipment or clean up residues to ensure production safety and product quality.
- Typical Scene:
- purging of pipeline before overhaul or switching process, use compressed air to remove residual chemical raw materials or gases in the pipeline, which shall be calculated according to the pipeline volume, purge pressure and purge times.
- Equipment cleaning: Clean up the sediment in the reaction kettle, filter or heat exchanger, and determine the gas consumption according to the size of the equipment and the difficulty of cleaning.
- Safety purge in flammable and explosive areas (e. g. storage tank area), the replacement of combustible gas with compressed air shall comply with safety regulations (e. g. purging time, replacement efficiency).
- Calculation Points: The amount of gas used for purging is usually intermittent, but peak flow needs to be considered (e. g. a large amount of gas used in a short period of time).
5. Safety and emergency gas consumption
refers to the compressed air reserved for safety systems (such as fire fighting, emergency shutdown) or emergency equipment (such as breathing apparatus, pneumatic tools) to ensure production safety.
- Typical Scene:
- fire protection system pneumatic fire monitor and fire valve shall be driven by compressed air and shall be calculated according to the specifications and coverage of fire fighting equipment.
- Emergency cut-off: Pneumatic emergency shut-off valve closes the pipeline quickly in the event of an accident to ensure that the instantaneous air supply is sufficient.
- Emergency Breathing: Provide clean air for staff (such as positive pressure air respirator), which should be calculated according to the number of personnel and the use time.
- Calculation Points: The safe gas consumption shall be designed according to the most unfavorable situation (such as triggering multiple safety devices at the same time), and sufficient margin shall be reserved.
Gas consumption calculation method and matters needing attention
- itemized calculation: The above types of gas consumption are calculated and summarized to obtain the total gas consumption.
- Coefficient of simultaneous use: Consider the overlap of gas consumption when different equipment or processes are running at the same time, and appropriately reduce the total gas consumption (e. g. take the coefficient of 0.7-0.9).
- Gas tank capacity: Configure gas storage tanks according to the fluctuation of gas consumption to balance the contradiction between supply and demand (e. g. gas tank replenishment at peak gas consumption).
- Selection of air compressor: Select the type and quantity of air compressor according to the total gas consumption, pressure requirements (such as 0.6-1.0MPa) and gas quality (such as oil-free and dry).
- energy saving optimization: Reduce energy consumption and improve gas efficiency through frequency conversion control, waste heat recovery and other technologies.
