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Silicon carbide pipe/nozzles in power plants

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Silicon Carbide Products in power plant

The main function of the silicon carbide nozzle of the burner is to inject the pulverized coal air mixture (primary air) supplied by the pulverized coal preparation system and the secondary air required for combustion into the furnace at a certain concentration and speed, respectively, so as to achieve stable ignition and combustion in the suspended state.

  • 1. The structure of silicon carbide nozzle must be simple, not easy to block, easy to repair and replace, long service life, and improve economic efficiency.
  • 2. The silicon carbide nozzle adopts an integrated casting molding process, which is high temperature resistant, wear-resistant and reduces maintenance costs.

The burner nozzles of power plant generally adopts cast steel structure. The proper swing of the burner nozzle can change the position of the flame center to adjust the reheat steam temperature level; The thick and thin pulverized coal burner can prevent furnace coking and high-temperature corrosion, and has the characteristics of stable ignition, good combustion stability at low load, and low NOx emission. After the primary air cast steel nozzle of the burner is burnt and deformed, the deviation between the furnace flame center and the design value is large, and the deviation between the nozzle size and the original size is large. The initial momentum of the jet is reduced compared with that before the burning loss, the range is shorter, and the rigidity is poor. The pulverized coal ignites near the nozzle, and the temperature near the nozzle is high, which is easy to produce slagging. The primary air nozzle of the burner needs to be replaced after it is burnt. During the replacement, the powder pipes connected to the outside of the burner need to be disconnected, the primary air nozzle of the burner and the nozzle should be pulled out together, then replaced, and then loaded. The workload is large, the environment is poor, and it costs labor, time, and money, resulting in great economic losses.

The silicon carbide nozzle of the burner produced by our company is wear-resistant, high-temperature resistant, non-deformable, and its service life is 3-5 times that of the cast steel nozzle, which improves the boiler efficiency, reduces NOX emissions, saves energy and environmental protection, reduces maintenance costs, and improves economic benefits.

It adopts integrated molding process, which is resistant to high temperature, abrasion and deformation.

 

The defects of cast steel nozzle mainly include the following aspects. 

1. The nozzle of cast steel is not wear-resistant, corrosion resistant, high temperature resistant and has short service life. The boiler needs to be shut down for replacement, resulting in great economic losses.

2. The cast steel nozzle is easy to be damaged during the operation of the unit, and the blunt body of the nozzle often falls off, threatening the operation of the burner and the safe operation of the slag extractor.

3. Because the nozzle material is G40Cr20Ni5, which works under high temperature for a long time, when the combustion of pulverized coal is unstable, it will cause uneven temperature distribution in the furnace or coking at the nozzle, resulting in thermal stress at the nozzle due to temperature difference, resulting in serious local deformation of the nozzle, short range of primary air, poor rigidity, pulverized coal ignition near the nozzle, high temperature near the nozzle, and local additional stress in the component. When the temperature fluctuation is large, The thermal stress changes greatly, causing thermal fatigue cracks on the nozzle surface, which will cause the burner nozzle and nozzle to burn over a long period of time.

4. Because the primary air flow is a high-speed gas-solid two-phase flow, the uneven scouring of pulverized coal particles leads to serious local wear of the blunt body and even wear off the blunt body. The nozzle and the blunt body are integrated. On the other hand, the thermal stress at high temperature is easy to cause serious deformation of the nozzle, even burning out, so the nozzle can not play its due role.


Product Detail

Product Tags

Application

The burner nozzle is generally of cast steel structure, and the proper swing of the burner nozzle can change the position of the flame center to adjust the reheat steam temperature level; Dense and thin pulverized coal burners can prevent furnace coking and high temperature corrosion, have stable ignition, good combustion stability at low load, and low NOx emissions. After the primary air cast steel nozzle of the burner is burnt out and deformed, the deviation between the furnace flame center and the design value is large, and the deviation between the nozzle size and the original size is large. The initial momentum of the jet is reduced compared with that before burning out, the range is shorter, and the rigidity is also poor. The pulverized coal catches fire near the nozzle, the temperature near the nozzle is high, and slagging is easy to occur. The primary air nozzle of the burner needs to be replaced after burning. During replacement, the powder pipes connected outside the burner need to be disconnected. The primary air nozzle and the nozzle of the burner need to be pulled out together for replacement, and then installed again. The workload is large, the environment is poor, and it is labor, time, and money consuming, resulting in great economic losses.

The burner silicon carbide nozzle produced by our company is wear-resistant, high temperature resistant, and does not deform. Its service life is 3-5 times that of the cast steel nozzle, which improves boiler efficiency, reduces NOX emissions, saves energy and environmental protection, reduces maintenance costs, and improves economic benefits.

Integrated molding process is adopted, which is resistant to high temperature, abrasion and deformation.

Comparison between silicon carbide nozzle and cast steel nozzle

1. The integral silicon carbide nozzle can effectively prevent contamination and slagging: when the boiler burns the coal easy to be contaminated and slagging, it is easy to have contamination, coking and slagging at the burner nozzle, thus affecting the combustion performance of the boiler. As the nozzle of conventional burner is made of cast steel, this material will deform under high temperature environment for a long time, resulting in uneven nozzle and eddy current;

2. Cast steel materials are also prone to high temperature corrosion. The nozzle surface is uneven due to corrosion pits, and the roughness is significantly increased. These two factors will lead to the problems of contamination, slag hanging and coking of the cast steel nozzle, which will seriously block the nozzle and cause potential safety hazards.

How to prevent the silicon carbide nozzle from clogging?

3. The silicon carbide nozzle has good temperature resistance, erosion resistance and corrosion resistance, which enables the silicon carbide nozzle structure to be kept flat, the surface to be kept smooth and clean, and the roughness to be low for a long time. These characteristics can enable the silicon carbide nozzle to still have good resistance to slagging and contamination when burning coal that is easy to coke and slagging. Moreover, the silicon carbide nozzle has the application performance of burning a large number of slagging prone coals such as Xinjiang coal, Mengdong coal, Zhundong coal, etc., which is good overall. It can significantly improve the coking and slagging problem of the cast steel nozzle, improve the combustion performance, reduce the maintenance workload, and save costs.

SNBSC materials

The main products of KSINO include SNBSC protection tubes, SNBSC bricks, SNBSC plates, SiC nozzles, wear-resistant products, wear-resistant pipes, concentrator nozzle, wear-resistant nozzle of pulverized coal burner, central air duct of pulverized coal conveying, etc. The products are widely used in many industries, such as electric power industry, steel industry, non-ferrous metals industry, chemical and building materials industry and so on. They have advantages of energy saving, environmental protection, high temperature resistance, corrosion resistance and so on.

Physicochemical Parameters

Physical Parameters Volume Densityg/cm3 Apparent Porosity% Normal temperature compressive strengthMPa Bending strength at normal temperatureMPa
  ≥2.65 ≤10.7 ≥170 ≥30
Chemical Parameters% SiC Si3N4 Fe2O3 FSi
  ≥60 ≥37 ≤1.5 ≤1.0

Performance and Application

1.SNBSC products have superior hardness, whose Mohs hardness is about 9. Among non-metallic materials, the hardness of SNBSC materials is only second to diamond.
2.SNBSC products have high strength at room temperature.
At the high temperature of 1200-1400℃, it almost maintains the same strength and hardness of SNBSC within normal temperature. Depending on different using atmospheres, the maximum temperature can reach 1650-1750 ℃.
3.SNBSC has small thermal expansion coefficient. Comapring the SiC and other material products, SNBSC products have high thermal conductivity, which is not easy to generate thermal stress. In the comparison, SNBSC products have superior thermal shock stability, long service life, high temperature creep resistance, corrosion resistance, extreme cold and heat resistance, and oxidation resistance. Thus, SNBSC materials can be easy to make products with high dimensional accuracy。
4.The products are widely used in steel industry, non-ferrous metals industry, chemical and building materials and other industries to save energy, protect the environment and reduce costs.
5.SNBSC products are also widely used in kiln and other industries. SNBSC material is a new type of high-grade refractory material. SNBSC products are formed by nitrogen high-temperature sintering. Then, the dense protective layer is formed on the product surface after high-temperature oxidation treatment. SNBSC products have an absolute advantage in the production of sanitary ware and high-grade daily-use porcelain.

Common SNBSC products

Kiln furniture
Pulverized coal pipeline
Pulverized coal air chamber assembly with SiC linings
Wear resistant pipe and elbow
SiC central air duct of power plant
Swirl burner accessories
SiC concentrator
SiC concentration ring
SiC burner nozzle
SiC coal chute
SiC burner
SiC flame stabilizing tooth
Secondary reheat SiC protective bushing
SiC separator
SiC stopper
SiC plate
SiC wear-resistant customized parts
SiC impeller
SiC lined pump


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