Blow Tank Research Articles

Prediction of Pressure Drop at the Entry Section from Top Discharge Blow Tank in a Pneumatic Conveying System

Although some literature can be found on the behavior of blow tanks, very few studies could be found on the pressure loss at the entry section to a pipeline (henceforth called entry pressure loss) from a top discharge blow tank in a pneumatic conveying system, even though its magnitude can be significant as compared to the total system pressure drop. This article presents the results of an experimental study carried out to assess this entry pressure loss. The results indicate that it is possible to scale up the entry pressure loss based on laboratory-scale tests with a reasonable degree of accuracy.

An Experimental Investigation into the Feed Rate Capacity of Rotary Valve and Blow Tank Feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.

Constrained model predictive control of blow tank consistency

Consistency control at the outlet of blow tanks and hi-density towers, the so-called double-dilution problem, is an area where further control development is needed. The task is to coordinate the manipulation of two input variables, coarse and fine dilution, to control the consistency, while simultaneously mid-ranging the fine dilution to keep it from saturating. This is made difficult by process nonlinearities, complex dynamics and tight manipulated variable saturation constraints. To address these problems, a model-based predictive controller (MPC) was applied to blow tank consistency control in a pulp mill. One of the unique features of the proposed MPC algorithm is that it is well suited to run on standard distributed control system (DCS) hardware of the type that already exists in most process plants. Several control strategies were tested, including MPC and the previously implemented scheme, with and without a ratio control scheme aimed at removing the dominant process nonlinearity. The results of a mill trial indicate that both controllers, when implemented as ratio controllers, give excellent disturbance rejection for production rate changes, keeping the consistency within 0.1% of target. However, MPC outperformed the conventional strategy in its response to setpoint changes and unmeasured disturbances, and was able to cope with actuator failure.

Pneumatic conveying of powders over long distances and at large capacities

This paper reviews design and operating requirements for long-distance and large-throughput pneumatic conveying. Emphasis is placed on: blow tank design to provide an efficient and controlled discharge of material; semi-empirical techniques to predict pressure drop with good accuracy; optimisation of stepped-diameter pipelines to minimise air flow, pressure, wear and power; reliable valves for abrasive and high temperature conditions; back-pressure unblocking techniques. These developments are advancing considerably the reliability and future potential of large-throughput and long-distance pneumatic conveying technology.

高温粉粒体供給の計測と制御

The author developed a new pulverized coal injection system using to the discharge nozzles of a blow tank of blast furnaces based on a pressure loss measuring method. He recommended a prediction and simulation method for the dense phase two phase flow of solid particles using a Jenike's cell instead of an actual pneumatic transport test.The author wants to develop a new mass flow measuring and control system for high temperature (above 1000°C) solid particles dense phase gravity feed. He describes a summary of the measurement and control methods that are known in printed publications for the above mentioned feed.The author wants to develop a new testing and extrapolation method for the high temperature solid flow characteristics of gravity feed as well as one using the Jenike's cell method for pneumatic transport.

Similarity of granular flow in a blow tank solids conveyor

By measuring velocity profiles of non-cohesive granular material for different feed rates at different times in a blow tank solids conveyor in which the conveying pipe exits at the upper part of the tank, it is found that there is similarity in the vertically downward component of solid velocity in a region distant from the free surface and from the pipe inlet where the particles are not fluidized.

Feed rate characteristics of a blow tank solids conveyor in transport of granular material

Feed rate characteristics of a blow tank solids conveyor in which the conveying pipe exits at the upper part of the tank are experimentally examined by the use of polyethylene pellets having a large minimum fluidizing velocity. The flow pattern of solid particles in the tank resembles suction flow at the pipe inlet and bears a strong resemblance to that of gravity discharge of solids from an orifice, and there exists a dead solids region on the porous support through which compressed air is blown. Within this region pipe inlet height from the porous support and tank size have no effect on the feed rate. For a given tank, the feed rate increases with an increase in pipe diameter. An empirical equation is proposed to relate these variables.

Pneumatic Transport of Solids by a Blow Tank System

Characteristics of a Fluxo-type blow tank conveying system for solid materials are examined experimentally. The discharge weight flow rate of the materials is fixed only by the air velocity blown into the tank and it is independent of the free falling velocity of the solid particle. With the weight flow rate being kept constant, the conveying air velocity can be increased by adding air into the pipe at the immediate downstream of the tank. The difference of solids flow pattern in the tank between fine particles and granular materials is visualized by the use of a small scale model tank of semi-circular crosssection.

Conveying Characteristics of Pneumatic Conveyor : Part 4, Minimum Velocity of Air Flow through a Pipe Required for Conveying Granular Solid and its Pressure as to Blow Off the Plugging Layer of Solids in Pipe

The authors have introduced a new formula for a minimum velocity of air flow required for the pneumatic conveyance of solid through a pipe. They have examined experimentally the minimum air quantity required for feeding a solid substance from a feeder of blow tank type. These studies are effective in deciding the air velocity and quantity required for the conveyance of solids through a pipe or to feed them from a feeder. Moreover they have introduced the formulas for the air pressure required for blowing off the plugging layer of solids in pipe.