Steam and Power Supply

For smaller plants or for supplementary purposes, steam and power can be supplied by package plants which are shippable and ready to hook up to the process. Units with capacities in the range of sizes up to about 350,000 Ib/hr steam at 750° F and 850 psi are on the market and are obtainable on a rental/purchase basis for energy needs. 

Modern steam plants are quite elaborate structures that can recover 80% or more of the heat of combustion of the fuel. The simplified sketch of Example 1.2 identifies several zones of heat transfer in the equipment. Residual heat in the flue gas is recovered as preheat of the water in an economizer and in an air preheater. The combustion chamber is lined with tubes along the floor and walls to keep the refractory cool and usually to recover more than half the heat of combustion. The tabulations of this example are of the distribution of heat transfer surfaces and the amount of heat transfer in each zone. 

Both process steam and supplemental power are recoverable from high pressure steam which is readily generated. Example 1.3 is of such a case. The high pressure steam is charged to a turbine- 

Start-up of plant section when rest of plant down Start-up of plant section when other plant on-stream Start-up of plant after maintenance Preparation of plant for its start-up on demand 

D2 Are the limits of operating parameters, outside which remedial action must be taken, known and measured (C1 above) 

D3 To what extent should plant be shut down for any deviation beyond the operating limits Does this require the installation of alarm and/or trip Should the plant be partitioned differently How is plant restarted ( 9.6) 

D4 In an emergency, can the plant pressure and/or the inventory of process materials be reduced effectively, correctly, safely What is the fire resistance of plant ( 9.5,9.6) 

D5 Can the plant be shut down safely Check the following  

---

Steam and power balances provide the link between the process utility requirements and the utility supply. The... 

In addition to using energy more efficiently in the process, another common strategy is to produce energy more efficiently. Many plants have their own on-site power plants that primarily exist to provide steam and power to the process units, but may also supply electricity to the grid when electricity price is high. 

After the process heat recovery is done, the next design step is to determine the utility supply in terms of heating and cooling, and power based on the needs and characteristics of process energy demand. In this step, the means of heat supply for the reaction and separation system will be addressed. For example, a choice for the reboiling mechanism must be made for a separation column between a fired heater and steam heater. Similarly, a choice of process driver between steam turbine and motor will be determined. Selection is made based on operation considerations, reliability and safety limits, and capital cost. Selection of process utility supply defines the basis for the design of a steam and power system. 

Energy supply optimization is about generating steam and power at the lowest cost via optimizing boilers and turbines. At the same time, it is about optimizing power... 

An example of where the utility optimization solution was applied was at a petrochemical site in Korea. The plant had three oil-fired boilers and three backpressure steam turbines that provide steam and power to the process units, and also supplied excess power to the national grid. The solution used the combustion... 

---