Reaction of high-pressure ammonia water in coke ovens with recycled ammonia water

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The interaction between high-pressure ammonia water and recycled ammonia water in coke ovens: High-pressure ammonia water and recycled ammonia water are two essential substances in the coke production process. Although both are referred to as “ammonia water,” they differ significantly in terms of their functions, pressure levels, and points of use. Below, I will explain in detail their respective functions and differences. Summary Comparison Table: Characteristics of High-Pressure Ammonia Water Circulation Ammonia Water
Core Function: Cooling waste gas during coal charging without producing smoke
Working Pressure: High (usually 2.0 – 3.5 MPa); Low (usually 0.2 – 0.4 MPa)
Injection Location: At the root of the riser (or inside the bridge tube); In the collector duct (with multiple nozzles)
Working Principle: Generates suction through high-speed jets; Cools directly by absorbing heat through evaporation
Operation Mode: Intermittent (used only during coal charging); Continuous (used throughout the coking cycle)
Destination of Ammonia Water: Enters the collector duct together with the gas after injection, becoming part of the circulating ammonia water; After cooling the gas, it flows into the gas-liquid separator along with tar and other substances, and is then reused after cooling.
I. Role of Circulating Ammonia Water: Circulating ammonia water serves as the “primary coolant” in coke oven production, and its function is continuous. Cooling and condensing raw gas: The raw gas that emerges from the carbonization chamber through the rising pipe is at a very high temperature, ranging from 650 to 800°C. After entering the gas collection duct, the high-temperature waste gas is intensely washed and cooled by a large amount of circulating ammonia water (at about 75–80°C), which is sprayed through multiple nozzles installed at its upper part. Ammonia water evaporates rapidly upon contact with hot gas, absorbing a large amount of latent heat, which causes the temperature of the gas to drop sharply to around 80-85°C. This is the main principle of the cooling process (evaporation absorbs heat). Preliminary purification of gas: During the cooling process, most of the tar and dust present in the raw gas are condensed and washed away, flowing away together with ammonia water. Transport medium: The cooled gas, the condensed tar, and ammonia water form a mixture that flows together toward the gas-liquid separator (also known as the tar-ammonia water separation tank) due to the slope of the gas collection pipes. Recycling: In the gas-liquid separator, ammonia water, tar, and tar residue are separated. Part of the ammonia water after separation (referred to as residual ammonia water) is sent for distillation, while the other part is cooled and then pumped back into the gas collection tube via a circulating ammonia water pump for reuse, which is how the term \"circulating ammonia water\" came about. In simple terms, circulating ammonia water is the key medium for ensuring the proper operation of gas collection pipes, as well as for cooling and transporting gas. II. The role of high-pressure ammonia water: Its function is intermittent and tactical, mainly used to address specific problems. Core function: Smoke-free coal loading. Background of the problem: After coke is removed from the carbonization chamber of a coke oven, it is necessary to reload coal into the high-temperature cavity (around 1000°C). At this time, a large amount of raw gas mixed with dust is emitted from the coal loading port and the furnace door, severely polluting the environment. Solution: At the start of the coal charging operation, by switching valves, high-pressure ammonia water (instead of steam or low-pressure ammonia water) is injected into the base of the riser or inside the bridge tube. Working principle: High-pressure ammonia water is ejected at extremely high speeds through special nozzles, creating a strong suction force (jet effect) inside the rising tube. This suction force forces the smoke generated inside the carbonization chamber to be drawn away, allowing it to enter the purification system through the gas collection pipes, thereby significantly reducing the amount of dust that escapes from the coal loading port and achieving \"smoke-free coal loading\". This is one of the most important environmental protection measures for modern coke ovens. Auxiliary cleaning: The strong impact force of high-pressure ammonia water also helps to prevent and remove the deposition of graphite and tar residues in the riser pipes and collection pipes, thus keeping the pipes unobstructed. The strong impact force of high-pressure ammonia water also helps to prevent and remove the deposition of graphite and tar residues in the riser and collector pipes, thus keeping the pipes unobstructed. III. The connection and coordination between the two Although they serve different functions, the high-pressure ammonia system and the circulating ammonia system are closely linked: They share the same source – high-pressure ammonia is usually obtained by diverting a portion of the fluid from the outlet pipe of the circulating ammonia pump, and then pressurizing it using a high-pressure ammonia pump. They all come from the same ammonia source (a circulating ammonia system). All converging at one point: After being sprayed through the riser, the high-pressure ammonia water carries along the drawn-in raw coal gas into the collecting main, where it mixes with the sprayed recirculated ammonia water to jointly accomplish the tasks of cooling and transportation. Conclusion: Circulating ammonia water serves as the “cooling circulation system” of coke ovens; it is responsible for continuously cooling and transporting coal gas. High-pressure ammonia water acts as an \"environmental protection vacuum cleaner\" for coke ovens; it is activated mainly during coal loading, using high pressure to achieve smoke-free operation, and is a key environmental protection facility.