In coking plant production, the high-pressure ammonia water circulating pump serves as a core environmental protection equipment. Though it appears to be an ordinary transfer pump, it directly determines whether smokeless operation can be achieved during coal charging of coke ovens, making it an indispensable key device for coking production lines. Many people tend to confuse it with ordinary low-pressure ammonia water pumps. In fact, the two types have clear responsibilities and different functions.
Simply put, low-pressure ammonia water pumps handle large-flow circulation to cool coal gas, focusing on stable flow and temperature reduction. The core task of high-pressure ammonia water circulating pumps is high-pressure boosting and atomization for dust removal. They are specially used to resolve flue gas overflow and excessive pollution during coke oven coal charging, acting as a core guarantee to meet environmental standards for coking production.
Its working principle is relatively straightforward. When the equipment operates, stacked multi-stage impellers build up pressure step by step. The ordinary ammonia water from the ammonia tank is pressurized to 1.8～3.0 MPa and delivered to special nozzles on the coke oven bridge pipe. At the moment coal charging starts, high-pressure ammonia water sprays out in fine atomized droplets, creating negative suction around the charging hole. All smoke, dust and raw coke oven gas generated during operation are drawn into the collecting main to prevent gas escape and realize smokeless coal charging. Meanwhile, it cools raw coke oven gas and adsorbs impurities. The ammonia water circulates and recycles for repeated use, delivering energy-saving and high-efficient performance. For such characteristics, corrosion-resistant self-balancing multi-stage centrifugal pumps are mostly adopted.
To adapt to the harsh working conditions in coking plants, the configuration of this pump requires careful selection. The transported alkaline ammonia water contains impurities such as tar and coal powder, which easily corrode and abrade components. Therefore, the wetted parts are generally made of 304 or 316L stainless steel. Copper fittings are completely prohibited to avoid corrosion damage. The self-balancing multi-stage centrifugal pump is the mainstream choice in the industry. It abandons the traditional balance disc structure, thoroughly solving common problems including rotor axial thrust, seizure and wear, and greatly improving operational stability. Equipped with an explosion-proof motor and corrosion-resistant mechanical seal, it fits the special coking conditions featuring flammability, explosiveness and leakage risks.
In daily operation, most failures of high-pressure ammonia water circulating pumps are caused by impurities in the medium. The most frequent issue is mechanical seal leakage: accumulated tar impurities abrade the sealing faces and lead to ammonia gas escape. Second, blockage of the inlet filter causes pump cavitation and fluctuation of outlet pressure, which directly impairs the smokeless dust removal effect. Long-term scouring also results in impeller wear and reduced equipment efficiency.
Daily operation and maintenance are critical to achieve durable equipment and minimize breakdowns. Plants generally adopt a "one operational, one standby" setup and regularly switch pumps to avoid long-term overloading of a single unit. Air inside the pump must be fully vented before startup to prevent cavitation damage. The inlet filter needs regular cleaning to intercept coal powder and tar impurities. During production, monitor pressure, vibration and bearing temperature in real time. Follow standard shutdown procedures: close the outlet valve first before stopping the motor.
In summary, the self-balancing multi-stage centrifugal pump is compact yet functionally vital. With stable high-pressure delivery and wear & corrosion resistance, it safeguards the bottom line of environmentally friendly production in coking plants. Proper pump selection and meticulous maintenance can reduce downtime caused by faults, greatly extend equipment service life and ensure efficient, green and stable operation of the production line.