Weekly topic for ammonia synthesis production: How to increase the production capacity of fixed-bed gas generators?

1. Appropriately increase the thickness of the gasification layer. 2. Use superheated steam at 220°C. 3. Select a furnace with a large and uniform air distribution capacity, appropriate for the type of raw coal used. 4. The lower the content of fine ash in the slag, the better. Such measures.

To ensure even distribution of the blast air over the entire coal layer in the furnace, 220°C superheated steam is used

I. Adoption of a water jacket for the new conical gas generation furnace. The jacket slag strip is strip-shaped, extending to the upper shell of the ash bin, with the upper and lower parts arranged in a sinusoidal pattern. The slag-breaking strips are arranged alternately at different heights to facilitate the formation of primary and secondary slag-breaking zones. By introducing the large slag lumps into the ash layer, they are broken down into medium-sized slag lumps, which are then removed again. This ensures a uniform distribution of the medium-sized slag lumps within the ash layer, thereby guaranteeing a even distribution of the gasifying agents. This helps to stabilize the furnace conditions and reduce the amount of residual carbon. II. The coal feeding section uses an automatic coal feeding system. III. Select the appropriate grate. The grate is a core component of a gas stove, and the amount of gas produced by the stove as well as its consumption level depend to a large extent on the quality of the grate. The basic requirements for grates are usually: (1) the raw materials must be highly suitable, have good elasticity, and allow for smooth operation ； (2) Strong slag breaking capacity, smooth slag discharge, and low operating load ； (3) Reasonable distribution of fibers, high air volume, high yield, and low coking rate ； (4) The flow channel is not clogged, there is little waste material carried away, it can withstand high temperatures, is resistant to wear, operates stably, and has a long service life. IV. Control of the ash angle of rest. The size of the \"angle of rest\" is determined by the diameter of the ash disk and the height of the ash outlet; it directly affects the slag discharge capacity and the operating conditions of the furnace. "If the \"angle of repose\" is too small, the resistance to the discharge of ash and slag is high, which can lead to accumulation of such materials and make it difficult to remove them. If the \"angle of repose\" is too large, the resistance to the discharge of ash and slag is low, resulting in easy flow and collapse, and thus an increased rate of carbon reformation in the ash and slag. A way to reduce carbon return in the slag is to slow down the speed of the furnace bars; as a result, the grate’s ability to stir and break up the slag decreases. The slag masses formed inside the furnace cannot be broken down in time, leading to uneven material distribution and uneven gas distribution across the same cross-section of the furnace. This worsens the furnace conditions, prevents an increase in air flow, and limits the ability to increase the load. When this phenomenon occurs, the damaged ash layer is more likely to wrap around the grates. V. The higher the operating temperature, the greater the vapor decomposition rate, resulting in higher gas production and better quality, as well as improved gas production efficiency. However, a high furnace temperature also accelerates the reaction rate of CO2 being reduced to CO; as a result, the CO content in the blast air increases, more heat is carried away, leading to greater heat loss and a decrease in the efficiency of the blast air. Furthermore, if the furnace temperature is too high, exceeding the ash melting point of the fuel, it can lead to scorching on the furnace walls, affecting normal operation. Therefore, the temperature of the gas generation furnace should be about 50°C below the ash melting point, and is generally controlled within the range of 1000–1200°C. Since the temperature of the vaporization layer cannot be measured directly in practice, the temperature of the furnace should be kept low to reduce the rate of fragmentation of the raw material when it is heated. The upstream temperature is generally controlled at ≤280°C. The upper part of the conical furnace has a narrow diameter, resulting in fast gas flow; if the temperature rises upward, the amount of gas carried away will increase rapidly. The downward temperature of the middle zone is generally maintained at 250–300°C, while the downward temperature of the particle zone is usually kept between 190–250°C. Ideally, the gasification layer should be positioned 300 mm above the grate air nozzles, so that heat can be accumulated to the desired temperature. This reduces heat loss and prevents scarring and sticking to the wall. VI. Increasing the wind speed provides more oxygen to the oxide layer, accelerating the oxidation of carbon and causing the furnace temperature to rise rapidly. It also reduces the residence time of carbon dioxide in the reduction layer, lowers the carbon monoxide content in the blowing gas, and decreases heat loss. However, if the blowing speed is too high, it is easy to blow small fuel particles out of the furnace, resulting in increased losses and the formation of wind tunnels within the fuel layer, which deteriorates the gasification conditions. VII. The longer steam is supplied into the gas generator, the greater the flow rate and thus the higher the amount of gas produced. However, if steam supply is excessive for too long, the furnace temperature will drop rapidly, which is unfavorable for gas production. Also, the steam flow rate is too high. The short contact time with the fuel results in a reduced rate of steam decomposition; as a consequence, more unreacted water vapor and carbon dioxide end up in the gas, which lowers the quality of the gas. Moreover, the unreacted steam carries away a large amount of heat from the fuel layer, leading to significant heat losses. Too little steam is used; although the contact time between steam and the fuel layer increases, which improves the quality of the gas, it reduces the production capacity of the gas furnace and can cause scorching or fouling. VIII. During the gas production stage, the fuel layer is thick, resulting in a longer contact time between steam and fuel. This not only leads to a higher rate of steam decomposition but also facilitates the reduction of CO2 in the gas, thereby improving the quality of the gas. However, during the blowing stage, the fuel layer is high, allowing for a longer contact time between air and fuel, which facilitates the reduction of carbon dioxide to carbon monoxide. Heat loss is high, and at the same time, the resistance inside the furnace also increases. The power consumption for conveying air increases. If the fuel layer is too thin, blowing air can easily create wind tunnels, affecting the quality of the gas and being detrimental to gas production. IX. Cycle time and its distribution: A longer cycle time results in greater fluctuations in vaporization temperature, gas production volume, and quality ； The cycle time is short, and the vaporization temperature as well as the gas production volume and quality remain relatively stable. However, the time required to open and close the valves is relatively long, resulting in a shorter effective gas production time; moreover, frequent opening and closing of the valves can lead to damage.

What was said upstairs is correct. The problem is that the content does not match the title. Could you give a brief introduction?

Reducing system resistance is a quite important aspect.

Reply 6# jingsan: Stabilizing the furnace conditions is a prerequisite for increasing the production capacity of gas furnaces.