Sterling Drug Inc.

Zimpro Inc.

Waterfront N.v.

Frederick M Lewis

George A Berken

A two-stage starved air furnace system is controlled to simultaneously achieve desired temperatures and percent stoichiometric air operation in the primary stage by modulating transformation relay functions acting upon measured temperature deviations to change both primary combustion air and primary auxiliary burner operation. At the set-point value of percent stoichiometric air, the relay functions are modulated in reverse direction to satisfy changing heat demands.

Method and apparatus for controlling auxiliary fuel addition to a

The present invention relates to a method for efficiently incinerating waste material, particularly dewatered sludge, in a multiple hearth furnace by controlling the temperature of the individual hearths of the furnace within certain prescribed limits by modulating the amount of combustion air, and controlling the temperature of the after-burner or combustion hearths to within certain prescribed limits by splitting the feed sludge between the first two upper waste material handling hearths.

Method for controlling temperatures in the afterburner and combustion

A method for controlling two-stage combustion furnaces having a first stage operated with sub-stoichiometric airflow and a second stage operated with excess air, whereby the first stage airflow is controlled such that the ratio of first stage airflow to total airflow is maintained less than ##EQU1## where N lies between zero and unity.

Furnace control method

The present invention relates to a method and apparatus for controlling the operation of a multiple hearth furnace system for efficiently incinerating combustible materials, such as sludge in which the air of combustion is essentially all introduced at the bottom of the furnace to incinerate solid materials. This control involves the following essential steps:

Method and apparatus for efficiently controlling the incineration of

The present invention relates to a method for efficiently incinerating waste material, particularly dewatered sludge, in a multiple hearth furnace by controlling the temperature of the individual hearths of the furnace within certain prescribed limits by modulating the amount of combustion air, and controlling the temperature of the afterburner or combustion hearths to within certain prescribed limits by splitting the feed sludge between the first two upper waste material handling hearths.

A process is disclosed in which any off-gas generated in a wastewater treatment plant, which off-gas has a low calorific (or BTU) value about one-tenth of that of natural gas, and usually even less, may be profitably burned in a multiple hearth furnace if the off-gas is first wet-scrubbed to a temperature below about 90.degree. F., then pre-heated by passing it through the center shaft of a multiple hearth furnace, before the pre-heated gas is burned. Such cooling of the off-gas by wet-scrubbing has the effect of lowering the moisture content of the wet-scrubbed gas sufficiently so that it may be advantageously pre-heated in the center shaft of the furnace and recycled to the hearths to assist in the combustion of sludge. In addition to providing desirable savings in auxiliary fuel usage, wet-scrubbed off-gas is unexpectedly cleansed of a sufficient amount of its corrosive components so as to permit ducting the wet-scrubbed gas in mild steel or cast iron equipment. Further, burning an odorous gas conveniently deodorizes it. The greater opening efficiency thus achieved provides more economical operation of a wastewater treatment facility. The process is most profitably utilized with decant tank off-gas ('DTO') which is generated in an amount about equal to the normal cooling gas capacity ('CG') of the furnace's center shaft, and which DTO is about equal to the volume of combustion air ('CA') which would be required to burn the sludge.

Process for utilizing low calorific value off-gases and simultaneous

A method of pyrolyzing sewage sludge to transform the same into activated carbon, with the combustible pyrogas and volatile liquids included therewith that arise from the pyrolysis operation being burned to sustain the transformation operation. A first portion of the hot activated carbon resulting from the operation is mixed with the wet sewage sludge to provide a dry sludge mixture that is subsequently subjected to the pyrolyzing operation. Water vapor that discharges as the hot activated carbon is mixed with the wet sewage sludge is heated by the burning of the pyrogas and transformed to steam. The resulting steam is in contact with the dry mixture during the pyrolyzing operation, and as a result the dry mixture is transformed to activated carbon. A second portion of the resulting activated carbon is separated from the first portion thereof, with this second portion being available for use apart from the method.

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Mountain View, CA, United States of America

Frederick M Lewis