The University of Waterloo

Alberta Oil Sands Technology and Research Authority

Edward Rhodes

John R Wynnyckyj

Robert Marr

Allan K Chambers

Donald S Scott

Fouling of the convection section of a steam generator by ash or other solid deposit from the product gas stream is monitored using radiation pyrometers which determine the temperature drop across a bank of heat exchanger tubes and calculation therefrom of a fouling factor related to the degree of fouling. Soot blowers are actuated, in manual response or automatic response, to the fouling factor, to effect cleaning of the heat exchanger tubes. Heat flux meters also may be provided to determine variations in the degree of fouling transverse to the flow of the gas stream and the determinations may be used to actuate selective cleaning of parts of the tube bank.

Convection section ash monitoring

A heat flux meter for measuring heat flux in a hot environment, such as, a coal-fired boiler, includes a cup-shaped body member of one-piece construction having an internal cavity in which is mounted an annular thermoelectrically-dissimilar member from that of the body member and in heat and electrically conducting contact with the body member. Electrically conducting wires of the same metal as the annular member enter the cavity and are connected to the center of the circular portion of the body member and to the annular member. An e.m.f. is induced by the difference in temperature between the center of the disc portion and the annular member. Since the body member is of one piece construction and the heat flux meter is sealed to the walls of the boiler, gases from the hot environment cannot enter the cavity and cause failure of the meter.

Heat flux meter

The tubular flowmeter is capable of measuring two different physical parameters in a flowing mixture of liquid and gas (such as wet steam). These measurements are such that they can be used to determine the individual gas and liquid flowrates. The flowmeter comprises first means, such as an orifice plate or a twisted tape, for causing an accelerational or frictional pressure drop in the total flow. Suitable means measure such pressure drop. Downstream of the first means, is positioned means for inducing rotational motion of the total flow, to cause the mixture to separate while remaining within the same conduit into discrete liquid and gas flows. Such means may comprise a rib extending helically along the inner surface of the flowmeter. Means, such as a pitot-static tube assembly, measure a pressure head indicative of the velocity of the gas flow. Downstream from this velocity measurement device, the two phases are permitted to mix freely again, all the time remaining within the same conduit. The total flow pressure drop and gas flow velocity head measurements are used to compute or determine the individual gas and liquid flowrates.

Two phase flowmeter

The build up of ash in a pulverized coal-fired boiler and other similar ash producing combustion operations is achieved by comparing the heat flux simultaneously detected by a first flux detector which is maintained free of deposits and a second flux detector on which deposits are permitted to form. The net values from the heat flux comparison is proportional to the heat flux which is not reaching the boiler walls as a result of the ash deposits.

Furnace wall ash monitoring system

The build up of ash in a pulverized coal-fired boiler is achieved by comparing the heat flux simultaneously detected by a first flux detector which is maintained free of deposits and a second flux detector on which deposits are permitted to form. The net values from the heat flux comparison is proportional to the heat flux which is not reaching the boiler walls as a result of the ash deposits.

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Waterloo, Canada

Edward Rhodes