Octadecylamine Boiler Shutdown Protection Agent

OctadecylamineShutdownProtectant

I. Product Characteristics: This product is a boiler shutdown corrosion inhibitor produced using modern advanced physical dissolution technology. It does not contain any other chemical components. The product has stable performance, is convenient to use without heating, disperses well in pure water, does not deteriorate or separate during long-term storage.
II. Basic Performance:
Item Indicator
Appearance White paste-like liquid Density (20℃) g/cm³ 0.98-1.03
pH (1% aqueous solution) 7.8-8.2 Content % ≥10%
III. Usage Requirements:
Drum pressure >7 MPa
Main steam pressure 420-470℃
Dosage: Calculated based on the water capacity of the water-steam system, the dosage is 150-200 mg/l (based on active ingredient);

IV. Usage Effect:

V. Usage Method and Packaging: Add via a dedicated dosing device to the deaerator outlet during unit sliding shutdown. Packaged in 25 kg plastic drums.
I. Overview of Pure Octadecylamine Protection Method:
Octadecylamine is an excellent method for the shutdown protection of thermal power units. Its protection of metals is based on forming a hydrophobic protective film on the metal surface. This film acts as a physical barrier, preventing contact between the material and water, moisture, or corrosive gases, thereby enhancing the metal's corrosion resistance to achieve protection.
Currently, the preferred method for using octadecylamine involves preparing it into an emulsion using special physical methods, without any additives. It is reliable to use, and good results can be achieved as long as the process is well-controlled. It is also important to emphasize that the dosing system should be promptly flushed after adding octadecylamine to prevent clogging of the dosing pipes.
II. Preparations Before Shutdown Protection
1. Dosing Equipment and Dosing System
1.1. If there is dedicated dosing equipment, ensure it is tested and operating normally before shutdown protection.
1.2. Dosing System Connection: Connect the outlet pipe of the dosing equipment to the outlet pipe of the feedwater ammonia dosing pump. Use condensate water for debugging to ensure the dosing pump operates normally at maximum flow.
1.3. If there is no dedicated dosing system, the ammonia (hydrazine) dosing system can be used. Calculate the required volume of the chemical solution in the dosing tank based on the pump's output (dosing time should be 1~2 hours). To ensure dosing effectiveness, consider using a phosphate dosing pump for two-point dosing. However, phosphate pumps generally have low output, so the chemical cannot be evenly distributed between the two points (calculate the dosage based on the pump's maximum output). When using ammonia and phosphate pumps for dosing, adjust both the frequency and stroke to the maximum to ensure rapid dosing.
2. Chemical Preparation and Mixing:
2.1. 200 kg of 10% octadecylamine emulsion is required.
2.2. Prepare the octadecylamine emulsion in the solution tank at approximately 3–5 times the volume. The main goal is to ensure the chemical can pass through the pump normally. There is no need for excessive dilution; generally, ensure the chemical is fully dosed within about 1~2 hours.
II. Octadecylamine Shutdown Protection Operation
1. To improve protection effectiveness, during the unit's sliding parameter shutdown, calculate the dosing time based on the shutdown schedule. Generally, start dosing about 4 hours before shutdown. At this time, the unit's operating parameters are low, and dosing takes about 2 hours. After dosing, allow 1~2 hours for circulation.
2. Before starting protection dosing, complete the following tasks:

2.1. Ensure the dosing device and chemical solution are in good standby condition:
2.2. Operate one feedwater pump, close the inlet valve of the stopped feedwater pump, close the primary valve of the ammonia dosing pipe for the stopped feedwater pump, and open the primary valve of the ammonia dosing pipe for the operating feedwater pump;
2.3. Partially close the deaerator exhaust valve;
2.4. Minimize the recirculation flow of the operating feedwater pump to zero;
2.5. Stop dosing for feedwater and boiler water;
2.6. Shut down the online dissolved oxygen meter, and keep the online pH and conductivity meters operational.
3. During the sliding parameter shutdown phase of the unit, and when approximately 4 hours remain until shutdown and boiler flameout (usually estimated based on the pulverized coal bunker level), notify the chemical department to start dosing via the shift supervisor (or unit head).
4. Chemical personnel should control the dosing to be completed within 2 hours. Condensate water can be added to the dosing tank to control the dosing time. After dosing, flush the dosing tank and dosing pump with water. Notify the shift supervisor (or unit head) after dosing is complete. The unit should shut down about 1~2 hours after dosing, close the main steam valve, and extinguish the boiler flame.
5. After dosing is complete, add condensate water (or demineralized water) to the dosing tank to flush the dosing pipes for about 0.5~1 hour. This prevents chemical deposition in the dosing pipes.
III. Protection Effect Check (If Necessary)
1. Check the hydrophobicity of the internal surfaces (steam-water side) of the deaerator, condenser, and drum, as well as the surfaces of turbine blades and heaters.
2. Perform tube cutting at the following locations to check the hydrophobicity of the tube samples:
Water wall Superheater Economizer Reheater
Cut tube length should be about 1 m. The cut tubes must not undergo any high-temperature cutting afterward.
IV. Other
1. During unit startup, follow normal operational controls.

2. After dosing begins, monitor water samples from each sampling point. When the water sample turns white and turbid, it indicates normal dosing. If no turbidity occurs, it means the chemical has not fully entered the system, and the dosing system (including the feedwater system) should be checked promptly.

3. Ensure no foreign objects are present in the chemical solution during preparation. Lumps of octadecylamine should be stirred to prevent pump clogging.

4. The condensate polishing mixed bed can be shut down about 1~2 hours after adding octadecylamine to ensure shutdown effectiveness.