Dual-drop SCR tail gas post-processing system

Release time:2019-04-26 17:27

Product technical route

According to the requirement of reformation and management of diesel vehicle market in use, the product not only meets the requirement of reducing PM in exhaust gas, but also meets the requirement of reducing NOX. Therefore, Zhongzi company specially developed the dual-degraded diesel vehicle aftertreatment product (DOC+DPF+SCR), which better meets the market demand.

Dual post-processing products work principle

  The DOC, DPF and SCR are integrated by Zhongzi Environmental Protection Company, and DOC+CDPF+SCR double-degraded post-treatment products are successfully developed (a catalyst with precious metal catalyst is coated on DPF carrier, namely CDPF). On the one hand, DOC in this product oxidizes NO to NO2 in appropriate temperature range, which provides sufficient NO2 for the downstream CDPF to achieve passive regeneration smoothly, and also provides NO2 for the fast reduction reaction of SCR. On the other hand, it makes use of the excellent fuel ignition of DOC to realize CDPF active regeneration smoothly, improve CDPF active regeneration efficiency, reduce fuel consumption and improve fuel economy.

This DOC+CDPF+SCR system integrates many modern advanced technologies, such as precious metal catalyst for diesel vehicle, selective catalytic reduction technology, polymer ceramic material, high precision sensor technology, SCR injection control technology and online monitoring and alarm technology. It is the leading product in the field of exhaust emission control technology of road diesel engine in China.

The product monitors the internal work of the system through temperature and pressure sensors in real time, and uploads it to the monitoring platform of the refitted vehicle. At the same time, it controls the processing of NOx accurately through multiple temperature, nitrogen and oxygen sensors, gas flow sensors or speed sensors.

By optimizing the integrated system of DOC+CDPF+SCR, the CO, HC, NOx and PM in the exhaust gas of the reformed diesel engine are obviously reduced, and the emission requirements are met. The fuel consumption of the product increases by no more than 5% after loading, and the urea consumption does not exceed 5% of the fuel consumption.
product type

  DOC+DPF+SCR, developed by SINOCAT Environmental Protection Company, includes air-assisted dual-drop tail gas treatment system and non-air-assisted dual-drop tail gas treatment system, and designs products with different structures according to the different layout of the original body.
Three Structures of Products

One-character structure
The structure is simple and practical, and can be disassembled for trucks or vehicles with cylindrical mufflers at the bottom of the original vehicle.

S structure
The structure is compact, the front and rear barrels can be side-by-side or turning links at different angles, and can be disassembled. The original muffler is arranged on the side of the car.

Box structure
It is the most compact structure and is very suitable for replacing square mufflers on most diesel trucks. Since the original muffler can be directly replaced, the fixed position and mode of the original muffler can be used for the installation and fixing of the product, and the installation of the product is convenient and firm. In this way, the structure of the whole vehicle will not change and the safety of the vehicle will be guaranteed.

Product performance parameterscontrol strategy
The self-contained control strategy is a model-based open-loop control strategy, which uses a hydrogen peroxide sensor and adds a feedforward control link.

Fuel adaptability

The self-made products can be adapted to the five-stage automotive diesel oil in China (sulfur content S < 10ppm). Our company's pre-sale and after-sales personnel and instructions will focus on the need to use more than 4 national standards of diesel, that is, sulfur content is less than 50 PPM. If my company's after-sales personnel have doubts about the use of non-standard diesel oil by users, we can consult with customers to sample the diesel oil in the tank and send it to the third party professional inspection agencies for oil identification.

The catalyst used in this system has excellent sulfur resistance and can work at least 200 hours under 350 ppm fuel. If the truck driver accidentally adds the substandard oil, it will not have an irreversible impact on the whole system in a short time.

Even if the sulfur content in the fuel reaches 3500 ppm, experiments have been done. Although the catalyst can continue to work after about 20 hours of use, its performance has been significantly weakened.


When the catalyst is switched to Guowu diesel oil, the sulfate covered on the catalyst can be removed from the surface of the catalyst (SO3-SO4) after about 30 minutes. The catalyst can also be successfully desulfurized and regenerated, and its performance can be significantly improved, basically reaching the initial performance state. It is proved that the modified catalyst can withstand diesel oil with high sulfur content in a short time to the maximum extent.

After extracting the online monitoring data of 100 diesel vehicles, it is found that the exhaust temperature is higher than 350 C. In addition, if the DOC effect decreases, the regeneration performance of CDPF decreases, and the exhaust temperature increases with the increase of back pressure. We can also heat and regenerate the post-processing system during maintenance to ensure that the service life of the system is not limited by occasional circumstances.

7. Product physical drawings (double-drop S-type product physical drawings)

8. Thermal Management Scheme
Same: Particle trap DPF

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