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Home-Application-SCR Tail Gas Treatment



The high-pressure linear delivery of urea solution is one of the important quality features of the SCR system (Selective Catalytic Reduction system also called Exhaust Gas Treatment System). Marine and vehicle diesel engines using traditional diaphragm metering pumps to deliver urea with large pulses for exhaust gas treatment, is difficult to achieve stable and smooth delivery. The MR series precision urea gear pump can achieve fast, accurate and high-pressure injection of urea solution, with features of high atomization uniformity, high neutralization performance, and stability & reliability, and is able to effectively purify carbon monoxide (CO), hydrocarbons (HC) and Particulate (PM) and other waste gas.


Current Situation of SCR Exhaust Gas Treatment Industry

“Since July 1, 2021, the national six emission standards for heavy-duty diesel vehicleswill be fully implemented nationwide, and the production and sale of heavy-duty diesel vehicles that do not meet the national six emission standards will be prohibited. Exhaust gas after-treatment technologies have been proposed and are under development, among which technologies such as catalytic oxidation (DOC), particulate filter (DPF), and selective catalytic reduction (SCR) of NOx are expected to be put into practical use. “ Selective catalytic reduction is also called SCR (Selective Catalytic Reduction) method. This technology can accelerate the reduction of NOx in the exhaust gas while effectively inhibiting the oxidation reaction, and can make the NOx conversion rate reach 90% without reducing the engine efficiency. Good fuel economy and high sulfur resistance. In order to meet the emission standards of China VI, Euro IV, and Euro V, the purification of exhaust gas reduces nitrogen oxides and fine dust particles for environmental protection and improvement of air quality in large port cities.



As one of the core components of the SCR exhaust gas treatment industry, the urea pump is responsible for pressurizing the urea solution from the storage tank to the injector or nozzle to ensure that an appropriate amount of urea enters the catalytic reactor. Choosing a safe, reliable and stable operation urea pump becomes cricial. What pump is suitable for the SCR exhaust gas treatment system?

Usually, the urea pump is used in the power system, and the following points need to be considered for the selection of the urea pump:

1. Quality, safety and reliability are very important;

2. In terms of function, the pressure is required to be about 0.7-1Mpa, the pressure resistance of the pump is 2.5Mpa, and the flow and pressure performances are continuous linear output;

3.The urea solution has certain corrosiveness, and at the same time, the urea solution has no lubricity; the flow contact material of the pump should be corrosion-resistant, and the friction parts should have self-lubricating properties;

4. The installation space is limited, requiring the pump to be small in size;

5. Maintenance cost.

Based on the above conditions, we will combine a variety of types of positive displacement pump to do an horizontal and vertical comparative analysis. (Centrifugal pump due to pressure limitations, temporarily not considered)

Horizontal comparison of traditional positive displacement pumps mainly include diaphragm metering pumps, screw pumps, gear pumps, etc.

Diaphragm metering pumps are plunger-type reciprocating pumps with metering functions, but there is pressure pulse in the delivery, which cannot meet the requirements of continuous delivery. At the same time, the diaphragm is short life and needs to be replaced regularly, making it difficult to maintain.

Screw pumps and gear pumps both belong to positive displacement rotor pumps. Traditional rotor pumps use metal rotors, which have no self-lubricating properties. They are suitable for conveying some viscous media, and their volume is relatively large. The rotor for conveying urea solution will be severely worn, and the pressure flow cannot be satisfied.

Is there any more fittable pump for SCR tail treatment system?

The emergence of micro magnetic gear pump is the perfect solution to the problem of pressurerized linear delivery of SCR urea solution. The micro magnetic gear pump has the characteristics of small flow, 0 pulsation, high linearity, high pressure difference, 0 leakage, and precise metering.

Next, we will focus on analyzing the micro magnetic gear pump.

Longitudinal analysis of the characteristics of various micro magnetic gear pumps.

Before understanding the micro magnetic gear pump, we must first understand the core gear material PEEK of the micro magnetic gear pump. Since the birth of PEEK special engineering plastics, PEEK has been used in precision structural parts, seals, bearings, gears and other fields. With the development of various modified additives(such as carbon fiber, molybdenum disulfide, glass fiber, PTFE, ceramics), various formulations of PEEK are derived, with different properties. Compared with pure PEEK, they have higher mechanical strength and better wear resistance. , PEEK with ceramic fillers has a service life more than 5 times that of pure PEEK, and can be used in various harsh working conditions.

The micro gear pump is developed based on PEEK modification technology. The micro gear pump can operate under low viscosity or even no lubrication conditions. At the same time, it adopts the magnetic coupling design to achieve high pressure with 0 leakage.

Various micro magnetic gear pump technical routes of domestic and foreign manufacturers at present:

Through the material modification of PEEK gear shaft and the breakthrough in processing technology direction;

Breakthrough in the direction of PEEK sliding bearing material and processing technology;

The structural design direction of the miniature magnetic gear pump has been improved.

Years of research and experience in micro magnetic gear pumps tell us that if the overall design direction is wrong, the accuracy, performance and life of the pump will be greatly reduced.

Material modification of PEEK gear shaft and breakthrough in processing technology

The gear shaft material is divided into two parts, one is the gear part, and the other is the shaft part.

The first solution: traditional European and American gear pumps (some domestic gear pump manufacturers), the gear material is mainly made of ordinary PEEK filled carbon fiber, the shaft is made of stainless steel 316L material, and it is used in occasions with small loads. It is processed by hobbing after injection molding into a cylinder. PEEK filled carbon fiber is easy to process, and the machining accuracy is good, but the shaft made of 316L is relatively soft. After running for about 5-6 months, the shaft will become more and more thin, and the gears will run out and wear seriously, until the pump body and gears are worn out, and it will not appear in short-term using.


Traditional PEEK+ SS shaft shaft abrasion situation

The second option: the gear material is made of imported PEEK, high-strength wear-resistant material, and the shaft is made of zirconia nano-ceramic material. Due to the difficulty of PEEK machining, many of them are formed by one-time injection molding of the tooth shape. The injection molding is easily deformed by the injection temperature. The gear processing consistency of each batch is poor, which affects the flow rate. Meanwhile, the production cost is low.


JONSN import PEEK+Nano-ceramic shaft

The third solution: the gear shaft of JONSN precision micro gear pump, the gear is made of high-strength wear-resistant PEEK material imported from the UK, the shaft is made of zirconia nano-ceramic material, and the gear is finished by precision CNC rolling. Through improving the coating of the tool material, and strict control of tool processing time, it solves the problem of imported high-strength wear-resistant PEEK gear processing. At the same time, the tooth shape is shaped by several hours of high-temperature molding heat treatment. The gear has high precision, stable size, smooth surface, high consistency, and long service life. The disadvantages are: High cost, it is suitable for heavy-duty high-precision occasions.

Breakthrough in the direction of PEEK sliding bearing materials and processing technology

The traditional bearing material is mainly made of ordinary PEEK filled carbon fiber material, which is easy to process, has weak wear resistance and load-bearing performance, it can only be used in light-load conditions.

JONSN precision grade miniature gear pump sliding bearing, made of special modified PEEK-based composite nanoscale ceramic formula, made of special processing and molding technology, high strength, strong resistance to dry wear, used in heavy-duty occasions, life up to 20,000 more than hours.

Improvement of the structural design direction of the micro magnetic gear pump

The structural design of the traditional micro gear pump has continued the American design (three-stage structure + PTFE diaphragm seal design) more than 20 years ago. The gap between the two ends of the gear is easily affected by the thickness of the gasket, resulting in large internal leakage and poor delivery accuracy. Inefficient, the structure is as follows:

传统三段式结构 拷贝

Three-stage structure design

The structural design of JONSN micro gear pump adopts (two-stage structure + static sealing ring design picture as follows), and its advantages are as follows:

(1) High assembly precision of the gear shaft;

(2) Reduce the number of sealing rings and reduce the number of leakage points;

(3) The gaps between the gear and the cavity are completely guaranteed by machining accuracy, with high matching precision and high consistency, and there is no need for manual grinding and repair of the gear and cavity. The more human intervention, the worse the consistency;

(4) The internal structure adopts a large-diameter flow channel design to reduce fluid movement resistance and ensure high transmission efficiency;

(5) Modular design, the motor can choose DC 24V, AC 380V or 440V motor according to the equipment space requirements;


According to the working condition requirements of marine SCR urea delivery system:

Flow rate: 130L/h; pressure: 10bar; marine voltage 440V, meeting the design requirements of classification societies.

The urea solution is required to be delivered with high linearity without pulse.

According to customer requirements:

The MR series precision micro magnetic gear pump is selected. The MR series precision micro magnetic gear pump has the characteristics of high delivery pressure and no pulse linear transmission. Combined with the gear pump selection application software developed by JONSN  to simulate and calculate the working conditions, The system selection scheme is as follows:


The system integrator can combine the SCR central closed-loop control system to control the speed to quickly, high-pressure, and accurately neutralize the specific amount of exhaust gas generated by the urea solution, especially when the load changes and stabilizes injection.

Jonsn application engineers believe that the exhaust gas treatment process is a complex calculation process. At present, urea pumps at home and abroad are also uneven. It is very important to choose a precision gear pump with reliable and stable quality. Through the simulation calculation of the working conditionsbythe selection application software, you can reduce the risk of use.

Jonsn has been approved by several classification societies, and the whole series of products have obtained the type certification of CCS China Classification Society.

Model-Confugiration code





Related certificates




Founded in 2010, JONSN is a company deeply involved in the R&D, production and sales of gear pumps. Since the establishment of Jonsn company, we have clearly put forward the business philosophy of " Focus on making each gear pump attentively". Jonsn has a gear pump assembly line, as well as gear hobbling machine, gear grinding machine, surface grinding machines, CNC machine tools, machining centers and all around comprehensive testing, and experiment equipments.  

Due to the changes in internal & external markets since 2019, Shanghai Jonsn Fluid Equipment Co., Ltd. made a new plan which was establishing new factory in the central region. Benefit from Ganzhou high-efficiency business environment and Ganzhou gear industry processing ability, the new factory was officially located in Ganzhou National Economic Technological Development Zone. Our factory has passed German TUV Rheinland ISO9001-2005 quality management system certification, China CCS, France BV, American ABS, Japan NK and other classification societies, and has obtained a number of patented technologies. The company has an excellent R&D and innovation team, cooperates with foreign companies, relies on our rich experience in the field of gear pumps for many years, through innovating technology, adopting new processes and new materials, optimizing the internal structure of the pump, and improving the gear pump. The quality and technical level of the pump have made major breakthroughs in a number of key technical fields of precision gear pumps. JONSN gear pumps have become key control equipment online delivery in many high-end manufacturing industries.

JONSN is a micro gear pump company that entered the field of marine SCR system application earlier in China. Jonsn occupies a large market share in the field of SCR exhaust gas treatment urea pump and has professional and mature solutions.

JONSN-MR precision micro gear pump has the following advantages in the SCR exhaust gas treatment industry:

1. Small and compact, providing a solution for limited space

The small and compact design of the JONSN-MR Precision Micro Gear Pump allows it to be easily integrated into existing SCR systems. Whether it's automotive, power or industrial, space is often at a premium and limited. This compact design provides greater flexibility for the SCR exhaust gas treatment equipment, enabling it to operate efficiently in a limited space and provide reliable liquid delivery support for the exhaust gas treatment system.

2. High-precision flow delivery to ensure the effect of exhaust gas treatment

JONSN-MR precision micro gear pump is able to provide precise flow and pressure output. In the SCR system, the precise injection of urea solution into the catalyst reactor and the full reaction of NOx in the exhaust gas is the key. Through the high-precision control of the precision micro-gear pump, we can accurate delivery of the urea solution,realzie the stable operation of the SCR system, improve the exhaust gas treatment effect, reduce the harmful gas emission , and make positive contributions to environmental protection.

3. Corrosion resistance, improve the reliability of equipment

In the SCR exhaust gas treatment industry, the use of corrosive liquids such as urea solution is very common. JONSN-MR precision micro gear pumps are usually made of corrosion-resistant materials, which can resist chemical corrosion and improve the service life and stability of the equipment. This corrosion resistance makes precision micro gear pumps a reliable choice in the SCR exhaust gas treatment industry, capable of continuous operation in harsh working environments, ensuring system stability and reliability.

On the whole, the application of JONSN-MR precision micro gear pump in the SCR exhaust gas treatment industry has obvious advantages. Its small and compact design enables it to meet the requirements of limited space, high-precision control ensures the effect of exhaust gas treatment, corrosion resistance improves the reliability of equipment, and low noise and vibration improve the working environment and operating comfort. It is an ideal solution for the SCR exhaust gas treatment industry!

JONSN Marketing Department (Original)