Adopting Gas Energy Shock Wave Rotary Soot Blower to Solve the Problem of Soot Accumulation in Waste Heat Boiler

At present, there are several types of soot blowing devices for waste heat boilers in the cement industry, and the appropriate soot blowing devices can be selected by analyzing their advantages and disadvantages.

2 the form and characteristics of several kinds of soot blower

2.1 mechanical vibration dust removal

Mechanical vibration dust removal is a traditional dust removal method, which is composed of a transmission device, a swing device and a spring anvil assembly device. The drop hammer is rotated by the transmission device. When it rotates to a certain position, the swing device is driven by the fork to lift to a certain height. When the pendulum falls freely, it hits the guide force shaft of the spring anvil and generates a suitable vibration frequency, the vibration mode of the natural frequency of the water wall is fully excited, the maximum effective vibration is obtained, and the best cleaning effect is obtained.

Advantages: simple structure, flexible and convenient control, widely used in traditional equipment, and good effect on floating ash. Disadvantages: high failure rate of mechanical devices, large maintenance volume, with the attenuation of transmission rod distance energy, poor cleaning effect on viscous ash.

2.2 steam soot blower

Steam soot blower is also a traditional way of cleaning ash, relying on the powerful kinetic energy release of high-temperature steam, directly on the heating surface for injection, a large number of large units used in the power industry.

Advantages: It can directly blow soot on the heating surface, has strong adaptability, and has good effect on coking slag ash and viscous ash. Disadvantages: the equipment is easy to jam, the failure rate is high, the maintenance requirement is high, and the pipeline at the soot blowing part is damaged.

2.3 sonic soot blower

The sonic soot blower is a soot blower developed in recent years and is widely used in waste heat boilers in cement plants. The principle is to rely on the vibration of sound waves to drive the vibration of dust in the flue gas, and then the dust is taken away with the flue gas.

Advantages: The sound wave is relatively non-directional, belongs to the dust removal without dead corners, and can receive sound wave vibration at every position and angle; only compressed air is required to generate sound waves, and the equipment is safe to operate; the power consumption is negligible and the operating cost is low. Disadvantages: The vibration ash cleaning of the sonic soot blower is greatly affected by the ash characteristics. For example, the ash cleaning effect on viscous ash and coking viscous ash is relatively poor, and it is only suitable for floating ash.

2.4 gas shock wave soot blower

The gas shock wave soot blower is a gas (usually acetylene) and air in a certain proportion, ignited by an igniter, and a micro explosion occurs in the shock wave generator tank, thus generating a shock wave, which acts on the ash of the heated area and cleans up the ash.

Advantages: large soot blowing force, good soot blowing effect at the corresponding position of the nozzle. Disadvantages: Because the nozzle is fixed, the directionality is strong, and there is a blind area for soot blowing; the operating cost is high, and acetylene is used as a fuel for micro-explosion, and the consumption is large; there are potential safety hazards, such as squibs and tempering; if the installation angle or position Improper, may damage the furnace wall, and blow damage occurs at the direct blowing part.

2.5 gas energy shock wave rotary soot blower

The gas energy shock wave rotary soot blower is a new type of soot blower that uses compressed air (nitrogen) as the medium, adopts instantaneous pressure relief release technology, and uses the energy of instantaneous supersonic fluid shock wave (shock wave) to remove boiler soot. The shock wave generator with special structure is used, the duration of each pulse is greater than 100 ms, and the shock wave intensity in the nozzle tube can reach Mach 5.

The principle is that after the plane normal shock wave in the tube leaves the nozzle, a spherical shock wave is formed. The diameter of the spherical shock wave continues to increase, and its center moves forward along the nozzle axis. At the same time, with the increase of the diameter of the spherical shock wave, the intensity continues to decay, and finally It weakens into sound waves. In the limited space of the boiler flue, the shock wave will be reflected and refracted by the four walls of the flue, and the transmission, refraction and reflection will be generated between the heating surface tube bundles. In the limited space, the effective action space of the shock wave will be larger than that in the free space field. The shock wave will be reflected at the physical interface between the ash deposit and the substrate, and can be introduced into the ash deposit through refraction. The intense pressure longitudinal wave of the shock wave will produce an effect of first pressing and then pulling on the ash deposit, causing the ash deposit to break. The refracted shock wave introduced into the ash deposit will also produce a transverse wave in the ash body, which will interact with the incident wave and the reflected wave to make the ash deposit separate from the substrate.

At the same time, due to the impact of shock wave and high-speed airflow, extremely strong nozzle noise is generated at the nozzle. The sound intensity is 160~170 dB at 1 m away from the nozzle, which will have a separation effect on the adhesion state of ash and coking on the heating surface, and cause fatigue fracture and crushing tendency of ash and coking. After the compressed air sprayed from the nozzle reaches the pipe wall of the heating surface, the ash scale layer and coking attached to it tend to crack and fall off.

The nozzle ejects high-speed airflow (speed> sound speed) after the shock wave, and the kinetic energy of the direct, refracted and reflected airflow directly acts on the ash and coking layer, so that the ash and coking attached to the surface of the heating surface are directly separated by the mechanical external force of the airflow.

Advantages: high air energy shock wave intensity and good soot blowing effect; The nozzle can be rotated and can blow soot without dead corners. Only compressed air is required for operation, and the consumption is very small, and the operation cost is almost negligible. Only compressed air equipment is needed to ensure safety. The soot blowing position is not fixed and there is no blow damage to the pipeline. Soot blowing intensity can be adjusted according to site conditions, with strong flexibility. Equipment failure rate is low. Disadvantages: Almost no disadvantages. Only the air source pressure is required, and 0.6~0.7 MPa is recommended. The air in the compression station of the general factory can meet the requirements. Only 0.6~0.7 MPa of compressed air 0.12 m3 is required for each shock wave release at a single point, and the cost is only 0.075 yuan (calculated by electricity charge 1 yuan/kWh). According to the ash accumulation, it is enough to blow soot for 1~2 times in each class.