What is chemical cleaning?
Chemical cleaning involves using chemical solutions to remove fouling stains from processing equipment. The cleaning operation could be solely chemical (like the use of mineral acids to break down inorganic salt scales) or it could be aided by physical techniques like steam or turbulent water movement. After cleaning, these pipelines must be free of all pollutants, including hydrocarbons, grease, oils, rust, scale, and others. Chemical cleaning is the process of removing hard deposits from surfaces of process equipment or pipelines by dissolving or loosening them with chemicals.
Procedure of chemical cleaning
Following are the steps :-
- Preparation work for chemical cleaning
The following tasks must be finished before beginning chemical cleaning procedures –
- Setting up and erecting temporary equipment, such as a circulation pump, a chemical injection pump, a chemical dissolving tank, and an ejector, a steam mixing heater, a hydrazine injection system, a waste neutralising tank, and a wastewater pump.
- Interconnecting pipework between temporary equipment and the permanent facility’s tie-in point. (To facilitate bypass, circulation, and other uses)
- Attaching the solution recovery line to the vent and drain with a rubber hose.
- At safety valves and unnecessary equipment, blind plates must be inserted.
- The system’s restricting orifice must be installed, item
- Checking the system’s lines and valves, including any temporary piping,
- Water flushing and leak test
Until the drainage has been visually clear, water flushing must be done using a temporary circulation pump.
After water flushing, water must circulate in the cleaning loop and be pressurised to the Circulation Pump’s maximum pressure. If there is a leak, it must be fixed.
- Heating up
After establishing water circulation, steam from the existing steam line must be added to the cleaning system. Heating must continue until the temperature reaches 70°C.
The contractor must fill the Chemical Injection Tank with the necessary amount of chemicals while the heating process is underway. Following the completion of the heating process, the chemical solution must be injected into the system being cleaned by the Chemical Injection Pump.
Under atmospheric pressure, the cleaning solution must be drained from each low point. Effluent, including the waste water produced after rinsing, must be conveyed to neutralisation facilities provided by the contractor. Until the cleaning system is filled with water, water must be supplied into it. Down Flow must provide the initial flushing prior to filling.
After establishing water circulation, steam from the cleaning system’s existing steam line must be added. Heating must continue until the temperature reaches 70°C.
- Acid cleaning
The contractor must put the necessary chemicals in the Chemical Injection Tank while it is heating up. The chemical solution must be injected into the system to be cleaned once the heating process is complete. Acid cleaning must be done while maintaining continuous circulation.
The system must stop steaming into the cleaning loop and be allowed to cool naturally to 60°C while maintaining continuous circulation.
A steady injection of ammonia is used to ammoniate the circulating solution, bringing its pH up to between 8.5 and 9.0. At each stop along the cleaning loop, the pH must be determined.
In the chemical dissolving tank, sodium nitrite must be prepared as a passivation agent before being introduced into the chemical cleaning loop.
- Final rinsing
Under positive nitrogen pressure, the cleaning solution must be drained from every low point. Effluent, including post-rinsing effluent, must be delivered to the contractor’s provided neutralisation facility.
- Final Drain Out
Rinsing water must be removed and air must be blown. Nitrogen purging ought to be done upon completion for prevention.
Pipingmart is B2B portal specializes in industrial, metal and piping products. Also, share latest information and news related to products, materials and different types grades to help business dealing in this industry.