Efficiency heater

Assume compressors are adiabatic with 100% efficiency, heater and cooler are isobaric, and both hot and cold sides of the heat exchanger are isobaric. 

Replacement of inefficient heaters with more efficient heaters. 

Depending on the kinds of commodities and services and their market prices (i.e., the costs of labor and services supporting them), we may cause the expenditure of more energy than the amount previously saved by using a more efficient heater. 

Efficient heater operation requires that excess air entering the convection section be minimized, whieh is indicated by a very small negative pressure at the convection section inlet. To achieve this, it should have a well balanced draft pressure profile between the firebox and stack. The hot gas pushes so that the pressure is always greatest at the firewall while the stack draft pulls. When this draft is eorreetly balanced, the pressure at the bridge waU should be around 0.1-0.2 WG (water gauge). Too mueh draft allows cold air leakage into the fired box resulting in wasted fuel. 

The Stamicarbon wastewater system consisting of two desorbers, hydrolyzer, hydrolyzer heater, reflux condenser, desorber heat exchanger, and a wastewater cooler is very efficient. Also, in many plants, as the water contains less than 1 ppm of NH and of urea, it can be used as cooling water make-up, or boiler-feed water. 

High efficiency compressors with crankcase heaters... 

Fired Hester a.s a. Reactor. When viewed as a reactor, the fired heater adds a unique set of energy considerations, such as. Can the heater be designed to operate with less air by O2 and CO analy2ers How does air preheating affect fuel use and efficiency How can a lower cost fuel (coal) be used Can the high energy potential of the fuel be used upstream in a gas turbine ... 

Fired Heater as a Heat-Exchangee System. Improved efficiency in fired heaters has tended to focus on heat lost with the stack gases. When stack temperatures exceed 150°C, such attention is proper, but other losses can be much bigger when viewed from a lost-work perspective. For example, a reformer lost-work analysis by Monsanto gave the breakdown shown in Table 2. 

Equipment Tests. Procedures for rigorous, detailed efficiency determination are available (ASME Test Codes) but are rarely used. For the objective of defining conservation potentials, relatively simple measurements are adequate. For fired heaters, stack temperature and excess O2 ia stack should be measured for turbiaes, pressures (ia and out) and temperatures (ia and out) are needed. 

Fields of Application One of the major advantages of the gravity-bed technique is that it lends itself well to true intimate counter-current contacting of solids and gases. This provides for efficient heat transfer and mass transfer. Gravity-bed contacting also permits the use of the sohd as a heat-transfer medium, as in pebble heaters. 

A simple vei tical cylindrical heater has vertical tubes arrayed along the walls of a combustion chamber fired vertically from the floor. This type of heater does not include a convection sec tion and is inexpensive. It nas a small footprint but low efficiency, and it is usually selec ted for small-duty applications (0.5 to 21 GJ/h [0.5 to 20 10 Btii/hj). 

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