Stream connections

A second property, closely related to the first, is the abiHty of the heat pipe to effect heat-flux transformation. As long as the total heat flow is ia equiHbrium, the fluid streams connecting the evaporatiag and condensing regions essentially are unaffected by the local power densities ia these two... 

Run-around coils. Where the incoming and outgoing air streams are remote it is necessary to use a run-around coil to couple them. A pumped liquid to a heat exchanger in the cold stream connects a heat exchange coil in the warm exhaust. The effectiveness can be up to 60 per cent. 

Show each significant step as a block, linked by lines and arrows to show the stream connections and flow direction. 

This chapter covers the preparation and presentation of the process flow-sheet. The flowsheet is the key document in process design. It shows the arrangement of the equipment selected to carry out the process the stream connections stream flow-rates and compositions and the operating conditions. It is a diagrammatic model of the process. 

Uj i i = the fraction of the total flow of component k entering unit i that leaves in the outlet stream connected to the unit j the split-fraction coefficient , gi 0 lc = any fresh feed of component k into unit i flow from outside the system (from unit 0). 

A reactor is represented as two units (Figure 4.10). The split-fractions for the first unit are chosen to account for the loss of material by reaction. The second unit divides the reactor output between the streams connected to the other units. If the reactor has only one outlet stream (one connection to another unit), the second unit forming the reactor can be omitted. 

Where each D, i l,2...,p represents the topology of each disjoint subsystem. The agregation of the balance equations to form the chain of disjoint subsystems, eliminate the streams among the units of each disjoint system. This leaves only the streams that will connect a particular disjoint system with similar others. These streams together with the streams connected to one unit are called external and the parameters belonging to these streams are called external parameters. 

The first step in setting up a process for the sequential modular approach is to reconstruct the process flowchart in terms of blocks or modules (process units or operations) and streams connecting them. Several types of blocks and names that might be given to them are as follows ... 

Field tests were conducted on a slip-stream connected downstream of the multicyclone, on a 5MW-bark fired boiler. The instrumentation of the set-up was as indicated in Fig. 2. Connections for isokinetic dust sampling (gravimetrical determination) were mounted on the upstream and downstream side of the filter unit. The following signals were connected to the data acquisition unit for continuous sampling of Pressure difference, between filter inlet and outlet (PTl) volume flow... 

Two extremes are encountered in flowsheeting software. At one extreme the entire set of equations (and inequalities) representing the process is written down, including the material and energy balances, the stream connections, and the rela-... 

Once the information flowsheet is set up, the determination of the process topology is easy, that is, you can immediately write down the stream interconnections between the modules (or subroutines) that have to be included in the input data set. For Fig. 5.5 the matrix of stream connections (the process matrix) is (a negative sign designates an exit stream)... 

Travers, K., 2005. The leaf-stream connection, The Volunteer Monitor, 17(2) 16-17. 

Now, for each stream connecting a source and a target plant region, a... 

Figure 2. Recycle CFE device, a. Schematic of elution port to inlet port connection. Eluant is continuously reinjected at the chamber inlet. Feed is injected into one of the recycle streams, b. Schematic of complete RCFE device. Recycle streams connect the elution and inlet ports in the recycle section. Separated products are recovered through the elution ports flanking the recycle section, and an equal volume of buffer is fed through the inlet ports on either side of the recycle section.

Sensitivity analysis can show which plantwide manipulated inputs (setpoints of BFS control) are necessary. Variability of the streams connecting BFS indicates which disturbances must be rejected. In this way, the designer can identify control objectives of the basic flowsheet structures, and set them as explicit targets for design. 

Chemical conversion of impurities in R4 makes possible alternative recycle structures by keeping the same equipment, but changing the stream connections. The recycle of impurities to Rl may cancel. Figure 17.17 shows three supplementary alternatives to die base-case. 

The neutralising agent and process water are fed to the homogeniser via a flow control system. The alkali stream is normally split in two streams a main stream (90-95% of required amount) and a secondary stream connected to the paste pH control (see 5.6.1.). 

The reader can certainly imagine the case where there are more than two cooperating plants interconnected by energy streams only, with arbitrary numbers of streams connecting the plants with the environment. We obtain again a partition such as in (3.1.9), with several matrices C, C2, and row vectors a, 0C2, . Each of the matrices (3.1.10) is that of a connected graph (node n is formally split into two or more environment nodes). 

To summarise, besides mass streams, there are two utilities, electric energy and steam. The System is connected to the environment which consists of several environment nodes. The introduction of several environment nodes may look confusing. The reason for that is the need for keeping information about detailed source or destination of streams connecting the system with the... 

Whereas the two above mentioned cases do not hinder carrying out the balance calculations, an excessive use of fixed quantities (constants not affected by reconciliation) can make the balance problem unsolvable. Fig. 13-5c shows a simple case where all streams connected with a node are fixed. If the values of the flows are chosen independent one from another, the balance equation around this node will probably not be satisfied. The following Fig. 13-5d illustrates the same problem in a slightly more complex form (fixed streams around subsystem formed by two nodes). 

The statistical method conceives the computed balance difference as a random quantity which is function of flow measurement precision for streams connected with the node, and which is characterised by the maximum measurement error. In the IBS, the value of is found using pertinent statistical tables. Another method of gross error detection is computing the generalized least squares criterion (2 , see Section 9.4. 

---