Landing, tank cleaning, and tank bottom oil sludge

1. Scheme Description

Processing objectives: landing oil sludge, tank cleaning oil sludge, pool bottom oil sludge, etc.

Recommended technical route: Different pre-treatment methods are adopted based on the properties of oil sludge from different sources: screening and damaging the "landing oil sludge" with high solid content; Heat wash and separate the viscous tank cleaning oil sludge, and after initial reduction and resource utilization, enter the drying system together with the bottom oil sludge for drying treatment. The oil sludge that has undergone quality separation pretreatment enters the vacuum thermal desorption device to deeply recover the "oil" in the sludge.

Disposal objective: To deeply recycle the "oil" in the sludge, and reduce the oil content in the treated sludge to below 0.3%, achieving a harmless level.

2. Process flow

Figure 1 Process flowchart

After being mechanically screened and crushed, the landing sludge can be directly transported to the thermal desorption device. The screening and damage device can effectively remove impurities (stones, bricks, metals, plastics, etc.) carried in the oil sludge, while homogenizing the material, with a maximum size of 10-30mm, making transportation and thermal desorption more efficient and stable.

The bottom oil sludge is not suitable for direct entry into the thermal desorption device due to its high water content and relatively high solid content. This project adopts the "turbo thin layer drying process" to reduce the water content of the bottom oil sludge to below 25%, increase the solid content to over 60%, and synchronously increase the oil content to over 15%. Then, the dry sludge is transported to the thermal desorption device for subsequent treatment. The sewage separated by the drying process is discharged into the self built sewage treatment station in the factory area, and after treatment, it meets the standard for discharge. The sludge generated by the sewage station is filtered by a screw press and returned to the input port of the drying machine for re drying.

"Clear tank oil sludge" contains high petroleum and water content, low solid content, and good fluidity. First, the "hot washing separation" process is adopted to increase the solid content by 2 times (reaching more than 20%), and then it is transported to the drying process section. Together with the "bottom tank oil sludge", it undergoes drying process and finally enters the thermal desorption device. The "regenerated crude oil" separated from hot washing is transported to the product storage tank through pipelines. The separated wastewater will be discharged into the sewage treatment station in the factory area, mixed with the wastewater generated from drying, and discharged after reaching the standard through the sewage treatment process.

3. Technological advantages

The plan not only considers the harmless treatment of oil sludge, but also fully considers the recovery and reuse of crude oil, taking into account system safety, stability, and automated operation.

At the same time, by combining different processes and utilizing by-products reasonably, the goal of resource utilization is achieved:

(1) The hot water required for the "hot washing separation" process is utilized from the waste heat of the drying process waste gas condensation cooling section; The mixed liquid required for the hot washing separation process should prioritize the use of wastewater generated from the drying process section (about 90 ℃). The proportion of mixed liquid to be added will be determined based on the composition, fluidity, and viscosity of the oil sludge;

(2) The heat energy required for the drying process and thermal desorption process is provided by heating the heat transfer oil in a gas (or diesel) boiler, respectively. The heat transfer oil system is equipped with heat transfer oil storage tanks, gas gathering devices, expansion tanks, circulating water pumps, temperature and pressure sensing instruments, etc;

(3) The final slag discharge and cooling water facilities for the hot desorption process should prioritize the use of wastewater treatment plants that meet the discharge standards. While cooling and suppressing dust, they should not cause secondary pollution of the slag;

(4) The final destination of the harmless slag material will be determined by the customer. A more mature disposal experience is to provide it to cement plants or brick factories at a low price or for free as an alternative raw material, which can also be used for paving or bedding in oil fields.