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David Mills - One of the best experts on this subject based on the ideXlab platform.

  • chapter 12 conveying capability
    Pneumatic Conveying Design Guide (Third Edition), 2016
    Co-Authors: David Mills
    Abstract:

    Detailed data on the pneumatic conveying of a wide range of materials is presented in this chapter to further illustrate the differences in the performance and capability of materials having a wide range of properties in terms of size, size distribution, and density. In the previous chapter low-velocity dense phase conveying was illustrated with materials having Good Air Retention properties and in this chapter, this is extended to materials having very Good permeability. Various comparative plots of data are also provided to illustrate the potential range of conveying limits for materials, the influence of Airflow rate on conveying capability, and the potential range of minimum Airflow rates and hence minimum values of conveying Air velocity. As mentioned before, virtually anything can be conveyed pneumatically and the bulk particulate materials included here have a mean particle size range from about 10 micron to 10 millimeters and material bulk densities range from 100 to 2380 kg/m3.

  • Chapter 12 – Conveying Capability
    Pneumatic Conveying Design Guide, 2016
    Co-Authors: David Mills
    Abstract:

    Detailed data on the pneumatic conveying of a wide range of materials is presented in this chapter to further illustrate the differences in the performance and capability of materials having a wide range of properties in terms of size, size distribution, and density. In the previous chapter low-velocity dense phase conveying was illustrated with materials having Good Air Retention properties and in this chapter, this is extended to materials having very Good permeability. Various comparative plots of data are also provided to illustrate the potential range of conveying limits for materials, the influence of Airflow rate on conveying capability, and the potential range of minimum Airflow rates and hence minimum values of conveying Air velocity. As mentioned before, virtually anything can be conveyed pneumatically and the bulk particulate materials included here have a mean particle size range from about 10 micron to 10 millimeters and material bulk densities range from 100 to 2380 kg/m3.

  • Systems that Modify Material Properties
    Pneumatic Conveying Design Guide, 2016
    Co-Authors: David Mills
    Abstract:

    In many industries and for many bulk solids, there is a need to convey particulate material at a low velocity or with as little Air as possible. Unfortunately only materials having very Good Air Retention or permeability have a natural capability for being conveyed at a low velocity in a conventional pneumatic conveying system. With low-velocity conveying, there is also the possibility of reducing power requirements and hence, operating costs. There are, therefore, many driving forces and it has generally been the manufacturing industry that has undertaken the necessary research in order to increase their own capabilities in the marketplace. Independent research work, however, has been undertaken and this has helped with an understanding of the mechanisms involved. Conveying trials with sandy and floury grades of alumina are reported in tests with bypass pipelines and it is shown how material properties can be modified so that low-velocity conveying can be achieved with these granular materials.

  • Case Study 1: A Fine Material
    Pneumatic Conveying Design Guide, 2016
    Co-Authors: David Mills
    Abstract:

    In this chapter a case study is considered for a pneumatic conveying system required to convey cement. The design is based on the use of data for the cement obtained specifically from a pneumatic conveying test facility. The necessary scaling of the data obtained from the test facility, to that of the plant pipeline required, is outlined step by step with detailed explanations and calculations. A particular complexity with materials such as cement, that have Good Air-Retention properties, is that the value of the conveying-line inlet Air velocity, which is a critical design parameter, is a variable in the analysis to be undertaken. It is, therefore, essentially an iteration process and so guidance is provided on how to achieve convergence of the equations. Because pipelines are available in standard incremental sizes, precise answers are not achieved, but Air supply pressure can generally be varied quite easily and so compromise will generally provide a satisfactory solution. Both Airflow rate and power requirements are evaluated as part of the design process.

  • The use of high pressure blow tanks for the pneumatic conveying of pelletised materials
    Handbook of Powder Technology, 2001
    Co-Authors: David Mills
    Abstract:

    Blow tanks are widely used in industry as a material feeding device in pneumatic conveying systems. Because of their flexibility in operation they are also widely used to obtain conveying data for system design purposes. This is because a single unit is capable of feeding a very wide range of materials. They have a very high pressure capability and are capable of operation over a large turn-down ratio. In this chapter, the issue of their control is addressed, particularly with regard to the conveying of pelletized materials. Blow tank control characteristics are also presented, to illustrate both the means by which control is obtained, and the degree of stability achieved in conveying. A comparison with granular and fine materials is also included. Pelletized materials generally have a very distinct pressure minimum point in their operating characteristics and this feature is clearly illustrated. For comparative purposes, similar material conveying characteristics, and blow tank control characteristics, obtained for materials having Good Air Retention, and for materials having neither Good Air Retention nor Good permeability, are also included, to illustrate the similarities and differences in material conveying capability, and the potential control of blow tanks used as conveying pipeline feeding devices for these materials.

Kenneth Williams - One of the best experts on this subject based on the ideXlab platform.

  • Solids Friction Factors for Fluidized Dense-Phase Conveying
    Particulate Science and Technology, 2003
    Co-Authors: Mark Jones, Kenneth Williams
    Abstract:

    There have been numerous correlations proposed for determining a solids friction factor ( u s ) for fully suspended (dilute phase) pneumatic conveying. Currently, there are no equivalent correlations that predict u s in nonsuspension dense-phase flows. In dense-phase conveying there are two basic modes of flow: plug/slug flow, which is predominantly based on granular products, and fluidized dense-phase flow, which is more suited to fine powders exhibiting Good Air Retention capabilities. In plug/slug type flow, the stresses between the moving plug of material and the pipe wall dominate the solid-phase frictional losses. In fluidized dense-phase flow the frictional losses are characterized as a mixture of particle-wall and particle-particle losses but are heavily influenced by the gas-solid interactions. In this paper, a series of calculations were performed on experimental data in order to estimate u s for four types of material conveyed in the fluidized dense-phase flow regime. The solids frictional fact...

Mark Jones - One of the best experts on this subject based on the ideXlab platform.

  • Solids Friction Factors for Fluidized Dense-Phase Conveying
    Particulate Science and Technology, 2003
    Co-Authors: Mark Jones, Kenneth Williams
    Abstract:

    There have been numerous correlations proposed for determining a solids friction factor ( u s ) for fully suspended (dilute phase) pneumatic conveying. Currently, there are no equivalent correlations that predict u s in nonsuspension dense-phase flows. In dense-phase conveying there are two basic modes of flow: plug/slug flow, which is predominantly based on granular products, and fluidized dense-phase flow, which is more suited to fine powders exhibiting Good Air Retention capabilities. In plug/slug type flow, the stresses between the moving plug of material and the pipe wall dominate the solid-phase frictional losses. In fluidized dense-phase flow the frictional losses are characterized as a mixture of particle-wall and particle-particle losses but are heavily influenced by the gas-solid interactions. In this paper, a series of calculations were performed on experimental data in order to estimate u s for four types of material conveyed in the fluidized dense-phase flow regime. The solids frictional fact...