Weyerhaeuser Company Limited

Gregory K Brock

Daniel M Shellhammer

David G Halley

Eugene W Arnold

Bruce R Knowlen

R Kent James

John D Karna

Pierre E Leroueil

The invention is a method for controlling sootblowing in a power boiler or chemical recovery boiler. The method comprises assigning the sootblowers into a number of groups. Sootblowers within a group are generally adjacent to each other and cover heat transfer surfaces having similar fouling deposit formation characteristics. Each group will typically have up to 4 sootblowers. Every sootblower is assigned a weight factor which is the percentage of the total number of sootblowing cycles that the sootblower will be operative. Every sootblowing cycle in the boiler begins with the most upstream sootblower group and proceeds progressively through all of the other groups in the direction of the flow of combustion gases until the most downstream sootblower group is reached. By blowing in this manner the dislodged fouling deposits from the upstream heat transfer surfaces are swept in the direction of combustion gases. This sootblowing strategy is designed to maintain the boiler at or near maximum operating efficiency. Reduction in sootblowing steam usage is a secondary consideration, even though in one installation the usage was lowered to about two thirds of that previously needed. On-line instrumentation to determine heat transfer characteristics can be used to modify the default values of the weight factors assigned to the individual sootblowers in order to accommodate on-line changes in operating characteristics. The method is well adapted for use either in a feedback or feed forward control strategy and may also be used with a combination of these techniques.

Boiler sootblowing control system

The invention is a method and apparatus for non-contact measurement of the length and height or diameter of geometrically regular objects. The objects enter a first measurement station where horizontally opposed echo ranging transducers make sequential differential measurements to determine the length and transverse position of the object. Position information is sent to a microprocessor. The object is then advanced under a transverse array of downwardly oriented echo ranging transducers. The microprocessor preferrably selects the single transducer located most closely to the mid-length position of the object to make a height or diameter measurement. In the case of cylindrical objects, the object should be oriented with its axis parallel to a line projected between the opposed length measuring transducers. As the object is moved by the diameter sensing transducer, the microprocessor selects the measurement indicating the shortest distance between the object and the transducer. Diameter of the object can then be readily determined. The invention is particularly well adapted for measurement of objects that may be randomly located across a moving conveyor system.

Method and apparatus for measurement of length and height of objects

A seed sowing system and method employing photoelectric sensing equipment to detect singulated seeds and to actuate stepping equipment that ensures separate delivery of seeds to individual planting loci. The seed may come to the sensing equipment via a singulator and a low-pressure air stream. The photoelectric sensor is actuated each time the air stream carries a seed past a certain locus, and the sensor, in turn, actuates a cyclic stepping device by which each seed in a cycle is delivered into a different delivery tube and from there is deposited in a separate receptacle of a shutter. The stepping device is interconnected electronically with shutter indexing mechanism, by which the shutter is advanced and reindexed after each row of its seed-receiving openings has received its seeds, which may come from a single cycle or from a plurality of cycles. When the shutter is filled, the shutter moves over a planting location, beneath which may be a flat or a rack of seed-receiving capsules, held in a receiving position below a distributing assembly. The shutter releases the seeds from the shutter into a distributing assembly, from which they fall into the flat or the capsules. The system is very rapid and has the advantage of being able to handle a wide variety of seed types of different shapes, sizes, and weights.

Optical electronic seed sowing system

Monitoring of the recirculated atmosphere of an oxygen pulping reactor to determine when the inflammability level of combustible gases in the reactor atmosphere has reached a predetermined percentage of the lower explosive limit (LEL) of the reactor atmosphere in terms of combustible organic vapors and carbon monoxide is disclosed. Continuous or discrete samples of the reactor atmosphere are taken at spaced regions, and the samples are applied to: (1) flame ionization detectors, which determine the concentration of combustible organic vapors (e.g., aliphatic, olefinic, aromatic, acetylenic, alcohols, aldehydes, ketones, etc.) in the samples; and, (2) carbon monoxide analyzers, which determine the concentration of carbon monoxide in the samples. The outputs of the flame ionization detectors are calibrated in terms of percent LEL for the contributing combustible organic vapors and, thus, provide percent combustible organic vapor LEL information. The outputs of the carbon monoxide analyzers are calibrated in terms of percent LEL based on the carbon monoxide in the samples. The outputs of the flame ionization detectors are compared and the highest percent output is applied to an alarm and recording subsystem. These outputs are also compared to determine if they are close to one another. If the comparison indicates that a substantial difference exists, a differential sensor activates a further alarm to denote a wide variance that may indicate a faulty detector channel. Similarly, the outputs of the two carbon monoxide analyzers are compared and the highest percent output is applied to an alarm and recording subsystem. Also, if the outputs are substantially different a differential indicator is activated. In addition, in an alternate embodiment, the highest flame ionization output is summed with the highest carbon monoxide analyzer output and the result applied to a controller that continuously controls the position of a vent valve, as well as to an alarm and recording subsystem. Finally, an oxygen analyzer is provided for measuring the oxygen concentration of at least one of the reactor atmosphere samples.

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Auburn, WA, United States of America

Gregory K Brock