Recycling process of non-condensable gas from waste tire oil refining

Non-condensable gas is one of the outputs of waste tire refining process, the yield is between 8%-12%, usually not as the final target product, directly treated by the desulfurization and purification system and then introduced into the heating unit for combustion, and the generated flue gas is treated by the flue gas purification system and discharged to the standard. The output of non-condensable gas from waste tire oil refining and the recycling process are as follows.

The energy required for 1 ton of waste tire refining is 1994MJ, which can produce non-condensable gas 80kg, and the calorific value of the gas is 30-40MJ/kg. The calorific value of combustible gas is calculated according to 35MJ/kg, and the heat utilization rate of refining equipment is calculated according to 80%, and the heat provided by the total combustion of combustible gas is 2240MJ. From this point of view, the non-condensable gas generated from waste tire oil refining can fully realize the heat required for tire oil refining, and it is very important to do a good job in recycling waste tire oil non-condensable gas.

In the actual production process, the non-condensable gas produced by a single waste tire oil furnace varies with the different process of cracking oil refining. In order to balance the balance of production and consumption of the gas, a reasonable staggered cracking and mutual gas supply are adopted to avoid the phenomenon of large amounts of filling gas and large amounts of recoverable gas caused by heating and gas production at the same time. At the same time, the combustible gas adopts the main pipe, the non-condensing gas generated by each oil furnace is summarized to the main pipe, after purification, the oil furnace that needs to be heated introduces the combustible gas from the main pipe, which is more conducive to the balance of production and consumption of combustible gas. Under ideal conditions, if the first oil furnace from the room temperature to 250-280℃ within 4 hours by natural gas as fuel heating, 4 hours later, the generation of gas tends to be stable, in the supply of its own oil furnace fuel at the same time, part of the fuel can be used as the second oil furnace start-up fuel; When the second furnace runs for 4 hours, it can also supply fuel to the third furnace, and so on.

It should be noted that in addition to flammable organic gases, the non-condensing gas produced by waste tire oil refining also contains H2S, NOX, COX, SOX and other polluting gases, so it needs to be purified before recycling. Non-condensing gas first. After being desulfurized by spraying water and lye, it enters the combustion chamber as fuel and then enters the flue gas purification and dust removal tower together with the gas combustion tail gas. The dust and smoke gas is introduced tangentially from the lower part of the cylinder through the induced draft fan and rotates upward. The dust particles are separated by the centrifugal force and thrown to the inner wall of the cylinder, where they are absorbed by the lye layer flowing in the inner wall of the cylinder, and discharged through the dust outlet with the water flow to the bottom cone to achieve the purpose of desulfurization and dust removal.

Due to the instability of non-condensing gas, that is, at certain times, there will be insufficient supply of gas and insufficient heat generation; Or there is an excess of combustible gas, the supply exceeds the demand, and due to the characteristics and safety of the non-condensable combustible gas itself, the surplus combustible gas can not be stored, and only the part of combustible gas can be burned. Therefore, according to the actual production situation, natural gas needs to be replenished at any time when there is insufficient gas to maintain the continuous and stable refining of waste tires. When there is excess gas, the excess non-condensable gas is burned (about 5-10%) through an independent non-condensable gas combustor.