Energy-saving improvement method of large melamine device with low-pressure process

Abstract

The invention discloses an energy-saving improvement method of a large melamine device with a low-pressure process. The method comprises steps as follows: S1, after carrier gas sequentially passes by a first carrier gas preheater, a second carrier gas preheater and a third carrier gas preheater, the temperature of carrier gas is increased from 190 DEG C to 400 DEG C; S2: an insulation gas heater is directly heated with the adoption of molten salt. According to the energy-saving improvement method of the large melamine device with the low-pressure process, although net byproduct steam with the gauge pressure of 1.2 MPa or 2.2 MPa can be produced at 5-6 t / h with an existing low-pressure-process melamine production process, energy of the byproduct steam comes from fuel coal, the energy utilization rate is relatively lower than that of a large boiler, and accordingly, a large amount of byproduct steam should be avoided to the greatest extent in process design; after improvement of the process, coal is saved by 0.152 t for melamine per ton, coal is saved by about 6840 t every year, the purchasing cost of coal is saved by 8,000,000 yuan, annual carbon emission reduction is about 10,878 t, and the energy saving and emission reduction effects are remarkable.

Description

technical field [0001] The invention relates to an energy-saving improvement method for a melamine plant, in particular to an energy-saving improvement method for a large-scale melamine plant with a low-pressure method, and belongs to the field of environmental protection and energy conservation. Background technique [0002] The production methods of melamine at home and abroad are divided into dicyandiamide method and urea method according to the raw materials; according to the process flow, there are gas phase quenching method, liquid phase quenching method and dry capture and re-refining method; according to the operating pressure, there are high pressure method and low pressure method. and normal pressure method; at present, the production of melamine at home and abroad generally adopts the process route using urea as raw material, and there are many technical routes for producing melamine with urea as raw material in China; the development of melamine production process...

AI Technical Summary

Problems solved by technology

[0002] The production methods of melamine at home and abroad are divided into dicyandiamide method and urea method according to the raw materials; according to the process flow, there are gas phase quenching method, liquid phase quenching method and dry capture and re-refining method; according to the operating pressure, there are high pressure method and low pressure method. and normal pressure method; at present, the production of melamine at home and abroad generally adopts the process route using urea as raw material, and there are many technical routes for producing melamine with urea as raw material in China; the development of melamine production process technology is developing in the direction of large-scale, energy saving and environmental protection , Each process technology has its own advantages and disadvantages: the high-pressure method process device runs smoothly, the production cycle is long, the labor intensity is low, and the product quality is stable, but the investment amount is large, the technical cost is high, the key equipment needs to be imported, and the energy consumption and production cost are high. ; Atmospheric pressure process used to be a widely used production process in China, but the scale of a single set of equipment is limited. When building large-scale equipment, due to the huge equipment, it will be limited by the difficulty of equipment processing and manufacturing and transportation exceeding the limit to a certain extent; In other words, the low-pressure process unit has less investment, low energy and material consumption, and has cost advantages. Although the existing low-pressure melamine production process can net by-product 1.2MPa (gauge pressure) or 2.2 MPa (gauge pressure) steam 5~6 t / h, but the energy of the by-product steam comes from fuel coal, and compared with large boilers, the energy utilization rate is relatively low