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Structure and process analysis of several fixed gas furnaces Introduction At present, the technological transformation of fixed bed intermittent gasification gas furnaces is very active. Successful technological transformation is intertwined with technological transformation that is futile or even counterproductive, forming a confusing and confusing situation. How can we use a pair of discerning eyes to see through this messy technological transformation, so that enterprises can avoid detours and obtain the best benefits in the shortest time? We must conduct a comprehensive comparative analysis of several gas stoves from their basic structures and processes. There are many types of fixed bed intermittent gasification gas furnaces in my country. Φ1980, Φ2240, Φ2400, Φ2610, Φ2650, Φ2800, Φ2740, Φ3000, Φ3200, Φ3300, Φ3600, Φ3800 mm, etc., but there are only 3 basic furnace types: That is, Φ1980, Φ2745, Φ3600, mm. Other furnace types are derived from these three basic furnace types. 1 Looking at the working operation from the structural relationship between the furnace diameter and the ash pan diameter. The ash pan diameter of the Φ1980mm gas furnace is 2820mm. The relationship between the two: (2820-1980) ÷2=420mm, the diameter of the ash pan of the Φ2740mm gas stove is Φ3520mm, the relationship between the two: (3520-2740)÷2=390mm, the diameter of the ash pan of Φ3600mm gas stove is Φ4440mm, the relationship between the two: (4440-3600)÷2=420mm. Why are the ash trays of several gas stoves 400mm longer than one side of the furnace? This is because: The materials, process principles, and the degree of ash generated during gasification of several gas furnaces are basically the same. The ash discharge port is designed to be 300mm to meet production needs. According to the requirements of the "accumulation angle of repose" of the material ash, which is 35°, the ash tray should be about 400mm wider than one side of the furnace. It can be clearly seen that the original designs of several basic furnace types are scientific and rigorous. However, with the passage of time, several basic furnace types have undergone technical transformation in production practice. The Φ1980mm gas furnace enlarges the furnace to Φ2240, Φ2400, Φ2610, Φ2650mm, until it is expanded to Φ2800mm. Because during the diameter expansion, the ash pan and furnace bottom are basically not enlarged. In order to prevent the occurrence of carbon flow and collapse, corresponding technical transformations such as "trapezoidal ballast breaking strips", "flow prevention plates", and "fake ash trays" have appeared. In gas furnaces derived from Φ1980mm gas furnaces, due to the repeated expansion of the furnace, the ash pan has been extended to Φ2820mm, destroying the "ash accumulation angle of repose", so in the process operation In order to prevent the occurrence of "char flow" and "char collapse" phenomena, the process operation is gradually increased to a higher temperature under the furnace, increasing the viscosity of the ash and the lower carbon layer, making the materials bond and support each other, and minimizing fluidity. This forms the operating characteristics of small gas stoves: The temperature under the furnace is high and the temperature above the furnace is low. The advantage of this operation is: The ash ballast formation rate is high, the coking rate is low, and the gasification intensity of the gas furnace is high. This is also an important reason why the "small nitrogen" furnace has high gasification intensity and low consumption for many years. The negative impact of this process operation is that the furnace grate and furnace bottom rotating device operate at a higher temperature, and the overhaul period is shorter, generally within one year. The Φ2740mm gas furnace has also been modified to expand the furnace diameter. However, the path it takes is completely different from the Φ1980mm gas furnace expansion transformation carried out by Huizhai. The diameter expansion of the Φ2740mm gas furnace also destroys the "angle of repose of ash accumulation", causing "char flow" and "char collapse". To solve this problem, the method is to reduce the height of the ash discharge port and add a "fake ash pan". As a result, "charcoal flow" and "charcoal collapse" are prevented. phenomenon, but at the expense of the high-intensity production of gas stoves. Under medium and low load production conditions, a low level of balance is achieved. The height of the ash discharge port of the Φ3000, Φ3200 and Φ3300 gas furnaces of China Nitrogen Plant is designed to be 240~280mm, which is 20~60mm lower than the original design of 300mm for the Φ2740mm gas furnace. The width of the ash discharge port is only 760mm, with the ash plow taking up one-third, and the effective width is only one-half of the Φ2600mm gas furnace. In order to adapt to the above-mentioned technical transformation, the process operation had to adopt the method of opening a fire furnace. The primary air volume is low, the blowing intensity is generally around 3200m³/m²·h, the dust is fragmented, the dust around Φ200mm is small, and the defocus rate is high. Both are expansion projects, but the methods of dealing with them are different and the results are completely different. 2 Looking at the process operation from the height-to-diameter ratio of the gas furnace, the furnace body of the Φ2650mm gas furnace is generally 5600~6000mm, and the height-to-diameter ratio is 2.2.: 1. The furnace body of Φ3000mm gas furnace is generally 5445mm, and the height-to-diameter ratio is 1.8: 1 Φ3600 gas furnace body is generally 6225mm, which is 1.73: 1 Due to the difference in height-to-diameter ratio, there are differences in the optional blowers for gas furnaces. The fan selected for the Φ2650mm series gas stove is D600 type, and the blowing air distribution is 6780m³/m²·h ； The fan selected for the Φ3000mm series gas stove is D700 type, and the blowing air distribution is 6000m³/m²·h ； The fan selected for the Φ3600mm series gas stove is D1100 type, and the blowing air distribution is 6600m³/m²·h ； It is obvious that the air distribution intensity of the Φ2650mm series gas furnace is higher than that of the other two furnace types, and its blower head is also higher than that of other furnace types. In actual production, due to the differences in the above conditions, the blowing intensity of gas furnaces varies greatly. The blowing intensity of Φ2650 series gas stoves is generally around 4520 m³/m²·h, the blowing intensity of Φ3000mm series gas stoves is generally around 3800 m³/m²·h, and the blowing intensity of Φ3600 gas stoves is generally around 4300 m³/m²·h. ； Right and left, blowing is the basis of gasification and power. It is obvious that the Φ3000mm series gas furnace still uses the Φ2740mm gas furnace because of its furnace structure, which causes the blowing air to form a beam opening in the upper part of the furnace and accelerates, making the wind blowing intensity lower. The Φ3600mm gas furnace has a part of the furnace structure in the "dome" structure. The blowing airflow cannot be well buffered and settled in the upper part of the furnace, and the wind blowing intensity is also obviously lower than other furnace types. In recent years, some people mistakenly believe that: Burning low-quality fuel or briquettes can easily blow over and is not suitable for fans with high wind pressure and large flow. As we all know, the important characteristics of inferior raw materials and briquettes are reduced heat generation and low ash melting point. In this case, for high-intensity production, the gasification efficiency must be improved. Therefore, it is necessary to increase the effective carbon layer and increase the heat storage capacity of the carbon layer, which requires the pressure and flow rate of the fan to be increased, and the height-to-diameter ratio of the gas furnace to reach 2: 1 or more. Especially in the case of burning coal briquettes, briquettes are flammable, have high void ratio, and are well ventilated, making them more suitable for operations with high carbon layers and large air volumes. The new gas furnace burns briquettes, and the primary air volume is higher than burning lump coal, which is an example of Xuanming. 3 Gas Furnace Jacketed Boiler and Process Analysis The main function of the gas furnace jacketed boiler is to prevent the medium and high temperature gasification layer materials from hanging on the wall of the carbon layer. However, in recent years, the technical transformation of some gas furnaces seems to have forgotten the original mission of the jacket, and regarded the jacket as a steam boiler whose main task is to produce more steam. For example, it is unrealistic to increase the height of the jacketed boiler infinitely, even to the point of "fully jacketed". The generation of a gas stove is an energy conversion process. The law of conservation of energy is a basic scientific law. The limited energy is used for gasification reaction to the maximum extent, which is the fundamental purpose. A jacketed boiler that is too high, or even a "fully jacketed" boiler, will inevitably use part of the heat to produce steam instead of gas. Especially in the down-blowing stage, the steam fills the upper air layer of the furnace. The steam temperature should have been increased in this range to improve the gasification efficiency. Because the jacketed boiler is too high, the steam temperature not only does not increase, but decreases. (Because the jacket temperature is lower than the steam temperature entering the furnace). This will inevitably lead to a reduction in gasification efficiency during the down-blowing stage, affecting gas output and quality.