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Computational Fluid Dynamics CFD

Computational Fluid Dynamics CFD

Computational Fluid Dynamics (CFD) is a method of simulating processes and devices connected with fluid flow, heat transfer and chemical reactions. The method uses well-known complex mathematical equations (Conservation of Mass, Momentum, and Energy) which are not enable to solve in even simple cases without powerful computers.

With increasing of computers power, CFD methods found application in many fields of science such as mechanical and power engineering. CFD software is able to obtain accurate information connected with:

  • Velocity distribution field.
  • Pressure distribution field.
  • Temperature distribution field.

Advantages of CFD modelling in opposite to conservative methods (physical modeling, field testing):

  • CFD modeling is almost always faster.
  • CFD modelling is cheaper (generally 20-40% less cost).
  • Obtain the same accuracy when it comes to flow field, velocity and pressure.
  • Enable to compute models in full size (most physical models are built to scale).
  • Enable to make simple and fast construction changes without additional cost.
  • Enable to investigate work of device in many conditions which is often impossible in laboratory conditions.
  • Enable to obtain full visualization of results in each location of device.
  • Models are stored on computers and might be use many times.

Continuous and very rapid development of computer power let claim that CFD method will be one of the most accurate and effective tool in solving engineering and mechanical issues.

Technical facilities, range of expertize

SBB Energy S.A. has many years of experience in using world class software ANSYS Fluent. Well qualified engineers staff is equipped with high processing-speed workstations what guarantee rapid and comprehensive solutions of different technical issues. SBB Energy S.A. ensures wide range of CFD support, including:

  • Assessment of technological solutions.
  • Identification of problem sources and offer of their solutions.
  • Technological processes optimization.
  • New technology development.

Exact range of work and technical support is customized for needs of each Client. Basic CFD works conducted by SBB Energy S.A. are:

  1. Combustion analysis in coal fired boilers.
  2. Flow analysis in pulverized coal duct.
  3. Flow analysis in swirl burners
  4. Flow analysis in windboxes.
  5. Assessment of proper injections ports placement in SNCR method.
  6. Optimisation of deNOx primary methods.
  7. Flow analysis of SCR systems.
  8. Calculation of pressure drop.
  9. Optimisation of shape for ducts and turning vanes.
  10. Calculation of heat transfer.

Exemplary calculation results from accomplished projects

  • Combustion analysis

In order to optimize combustion process as well as to design flue gas denitrification installations with the highest possible efficiency, SBB Energy S.A. uses numerical methods. It enables to conduct plenty of variant calculations which would be impossible during real facility tests. Calculation result of combustion in boiler with swirl burners is presented in figure 1. CFD calculation enables to determine temperature in any zone in combustion chamber.

Figure 1. Boiler with swirl burners – temperature

CFD calculations enable to define flow at the outlet from burner and visualize shape of a swirl in tangential firing boiler. Velocities vectors at two levels of combustion chambers as well as temperature profiles are presented in figure 2. This results enable to notice possible anomalies and give valuable clues during designing phase.

 

 

Figure 2. Model of tangential firing boiler – temperatures and velocities profiles

  • Flow calculations

Numerical analysis enable to calculate pressure drop, velocity profiles and examine flow pattern in investigated installation. Calculation results of pressure drop for deNOx SCR system are presented in in figure 3.

Figure 3. Pressure in SCR installation

Fuel flow in combustion chamber is a significant part of combustion optimize process. Particles path lines of pulverized coal are showed in figure 4. This results enable to investigate influence of nozzles tilt on particles trajectories.

Figure 4. Trajectories of pulverized coal particles

During modernization of boilers and mechanical facilities, a great deal of importance is attached to air flow pattern in ducts and burners. Figure 5 presents flow of air in modernized swirl burner.

Figure 5. Air flow in swirl burner

 

Figure 6 presents air flow in windbox of tangential fired boiler. This type of analysis enable to assess air flow for any vanes setting.

Figure 6. Air flow in windbox – velocity

CFD analysis is a perfect tool during designing phase of turning vanes in flow duct, calculating flow through pipes with dampers and during optimize shape of ducts. Figure 7 presents results from calculation of turning vanes in SCR installation.

Figure 7. Turning vanes in SCR installation

  • Heat flow calculations

Numerical calculation enable to count and calculate heat transfer in mechanical devices and heat exchangers. Figure 8 presents results from calculation of regenerative heat exchanger.

Figure 8. Heat transfer in regenerative heat exchanger

Numerical investigation enable to assess flow of small particels of any material. This type of symulation is used to determine flow of pulverized coal in ducts (figure 9).

Figure 9. Symulation of pulverized coal flow in coal duct – particle diameter, m

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