Flow rate flue gas

The instrumentation and control system of the furnace controls and measures important parameters such as fuel flow rate, flue gas composition, and furnace temperature. Below is a list of instrumentation and control equipment functions that will be discussed ... 

Fuel mass flow rate Flue gas temperature Excess air Flue gas mass flow rate Heat loss... 

Coal rate (1) Flue gas flow rate Flue gas specific weight Flue gas temperature Flue gas pressure at ESP inlet Inlet particle concentration (1) Collection efficiency t/h Nm /h kg/Nm °C mmH20 g/Nm % 16 175000 1.32 155 -150 10 16 99.6... 

Step 2. System calculations over the entire range of possible operating conditions are required. The range must cover from the air blower minimum flow point to the expander bypass point for all reasonable variations in the applicable parameters of COj/CO ratio, fresh feed rate, flue gas temperature, ambient air temperature, and so forth. 

Fast-fluidized retorted shale is cooled from 990°F (482°C) to about 175°F (79°C) by contacting it countercurrently with balls from the preheat section. Since the conveying (flue) gas is cooled and contracts as it rises, it may be desirable to reduce the vessel size accordingly in the upper portion to maintain the desired flow rate of gas. 

Cold air can be sucked into the furnace convective section through holes in the furnace skin. This reduces the efficiency of heat recovery from the hot flue gas. At lower crude rates, flue gas flow drops, but cold air in-leakage remains constant. Thus, at lower crude rates, holes in the furnace exterior will hurt efficiency more than at higher throughputs. A roll of aluminum tape can go a long way toward correcting this problem. 

Example 7 Radiation in Gases Flue gas containing 6 percent carbon dioxide and 11 percent water vapor by volume (wet basis) flows through the convection bank of an oil tube stiU consisting of rows of 0.102-m (4-in) tubes on 0.203-m (8-in) centers, nine 7.62-m (25-ft) tubes in a row, the rows staggered to put the tubes on equilateral triangular centers. The flue gas enters at 871°C (1144 K, 1600°F) and leaves at 538°C (811 K, 1000°F). The oil flows in a countercurrent direction to the gas and rises from 316 to 427°C (600 to 800°F). Tube surface emissivity is 0.8. What is the average heat-input rate, due to gas radiation alone, per square meter of external tube area ... 

Coal is fed as a paste containing 25 wt % water, and sorbent is fed diy by a lock-hopper system with pneumatic conveying. The top size of each feedstock is 3 mm in). The latent heat lost evaporating the water fed with the paste is compensated by increased gas turbine power output resulting from the increased flue-gas mass flow rate. For the 80-MWe unit, there are six coal feed points (one per 4.5 m" [48 ft"]) and four sorbent feed points (one per 6.7 m" [72 ft"]), all entering beneath the tube bank along one wall. The bed depth is... 

An inerease in ambient air temperature will deerease the available energy for the generator. This assumes that the fresh feed and eoke burn remains eonstant. The expander horsepower does not ehange, but the air blower horsepower inereases with inereased air temperature, eausing the exeess energy to deerease. Steam and water may need to be added to the flue gas flow at various points in the system to eontrol afterburning. In Figure 4-64, the solid eurves are for a normal flow of steam. The dotted eurves are for inereases in the steam rate by 3.05 times, 4.85 times, and 6.05 times the normal flowrate. 

At the rated duty point, the differential pressure eontroller is aetive. The inlet eontrol valve and trip valve are eompletely open. The main bypass valve is eompletely elosed and the small bypass valve eontrols the differential pressure. Approximately 96%-98% of the flue gas flows through the expander, with the rest passing through the small bypass valve, orifiee ehamber, and double slide valve to the expander outlet to rejoin the main flue gas flow. 

We assume one second as the basis for the calculations, and define A and F as the volumetric flow rates for air and flue gas, respectively. We will also adopt the consistent use of volumetric flow-rate units of cubic meters per second. 

These scrubbers have had limited use as part of flue gas desulfurization (FGD) systems, but the scrubbing solution flow rate must be carefully controlled to avoid flooding. When absorption is used for VOC control, packed towers are usually more cost effective than impingement plate towers (discussed later). 

Tier I The focal point of Tier I is the waste feed. This tier limits the hourly feed rate of individual metals into the combustion device. These limits have been developed by U.S. EPA and can be found in Part 266, Appendix I.5 U.S. EPA established these feed rate limits by considering flue gas flows, stack height, terrain, and land use in the vicinity of the facility. It determined acceptable air quality levels for each type of metal as a function of terrain, stack height, and land use in the vicinity of the facility. This value is also the waste feed rate, as Tier I assumes that 100% of the metals that are fed into the unit will be released into the atmosphere. 

After the flue gas leaves the combustion chamber, most furnace designs extract further heat from the flue gas in horizontal banks of tubes in a convection section, before the flue gas is vented to the atmosphere. The temperature of the flue gases at the exit of the radiant section is usually in the range 700 to 900°C. The first few rows of tubes at the exit of the radiant section are plain tubes, known as shock tubes or shield tubes. These tubes need to be robust enough to be able to withstand high temperatures and receive significant radiant heat from the radiant section. Heat transfer to the shock tubes is both by radiation and by convection. After the shock tubes, the hot flue gases flow across banks of tubes that usually have extended surfaces to increase the rate of heat transfer to the flue gas. The heat transferred in the radiant section will usually be between 50 and 70% of the total heat transferred. 

The air and gas supply of domestic appliances is usually adapted using the fraction of C02 in the flue gas. The changes in the minimum required amount of air and in the total flue gas flow rate cannot be taken into account, but are negligibly small. This also applies to the maximum C02 fraction for the combustion of common natural gas, which differs by less than 1%. Therefore the variations in equivalence ratio 0 remain within tolerable limits. 

Furthermore factors such as stoichiometric value, heat load and design of the burner as well as the combustion chamber have a significant impact on the emission of pollutant gases. Depending on the reaction of a combustion system to a changing equivalence ratio decisions can be made how to minimize the pollutant emissions by adapting the flow rate of air or gas. A combustion control system based on monitoring the CO fraction in the flue gas could thus be considered. 

The primary air flow rate and moisture content of the fuel was given before each combustion run. Flue gas samples were taken continuously and the bed temperature was monitored on-line. The bed weight and mass loss rate were also continuously measured. 

Mass flow rate of steam Flue gas temperature entering high-temperature side 1 Ibm/sec... 

A counter-flow heater as shown in Fig. 7.3a heats helium at 101 kPa from a temperature of 20°C to 800°C. The temperature of the heating flue gas (air) entering and leaving are 1800°C and 1200°C at 101 kPa. Find (A) the LMTD, rate of helium flow, and heat transfer based on a unit of heating flue gas, and (B) the LMTD, rate of helium flow, and heat transfer for a parallel-flow heat exchanger under these identical operating conditions. 

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