Exhaust gas stack

Abstract

An exhaust gas stack includes an elongate, tubular stack member having inlet and outlet ends and a central longitudinal axis. An end section is mounted on the outlet end and has open first and second ends, the first end connected to the outlet end of the stack member and a frustoconical passage extending between these ends. An inner duct section has a central axis co-axial with the axis of the stack member and is mounted centrally in the end section. An annular gas passage is formed between the duct section and the end section. An air plug is movable between an open position at which exhaust gases can flow through the inner duct section and another position at which the plug restricts or prevents passage of exhaust gases through this duct section. An actuator is connected to the plug in order to move it between an open and other positions.

Description

BACKGROUND OF THE INVENTION[0001]The present disclosure is directed to exhaust gas stacks and to apparatus and devices for controlling the velocity of exhaust gases exiting from exhaust stacks.[0002]A variety of exhaust gas stacks and exhaust ducts are known in industry for the purpose of exhausting gases from sources such as furnaces. Vertical exhaust stacks can vary in height and in some cases can be of substantial height. Existing conventional exhaust gas stacks are generally constant geometry (fixed discharge area) devices. In many cases, such stacks are sized so as to maintain approximately 4,000 fpm velocity at the stack discharge at the maximum flow rate for the particular exhaust application in order to diffuse the exhaust gases into the atmosphere as required by local building codes.[0003]With a conventional stack design, the velocity of the gases at the stack discharge will drop when the airflow volume changes to lower than maximum since the discharge area of the stack rem...

AI Technical Summary

Benefits of technology

"The present patent provides an improved exhaust gas stack and velocity control apparatus for use in exhaust systems. The exhaust gas stack has a net opening area that can be adjusted to maintain a predetermined exhaust airflow velocity at the outlet of the stack. It also has sound attenuating features and can use a smaller motor for the exhaust fan, resulting in energy efficiency. The velocity control apparatus includes an inner duct section and an end section with a frustoconical passage, and an air plug member that can be moved between an open position and a closed position to control the flow of exhaust gases. Overall, the present patent provides advancements in exhaust gas stacks and velocity control for improved performance and efficiency."

Problems solved by technology

As the exhaust air quantity drops, these dampers are opened to introduce outside air into the fan inlet chamber so that the fan delivers constant airflow at all times. However, the operation of this exhaust system is not energy efficient.

Another concern with a standard exhaust stack design is the amount of noise that eminates from the exhaust stack.

This is becoming a more significant problem for industry and for laboratories because the allowable noise levels that can be radiated to the environment is becoming more restricted by local by-laws and other legislation.

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