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Utility stream

In this context, the points correspond to process and utility streams and the lines to heat exchange matches between the heat sources and heat sinks. [Pg.214]

Equation (7.2) put in words states that the minimum number of units required is one less than the number of streams (including utility streams). [Pg.215]

Before any matches are placed, the target indicates that the number of units needed is equal to the number of streams (including utility streams) minus one. The tick-off heuristic satisfied the heat duty on one stream every time one of the units was used. The stream that has been ticked off is no longer part of the remaining design problem. The tick-off heuristic ensures that having placed a unit (and used up one of our available units), a stream is removed from the problem. Thus Eq. (7.2) is satisfied if eveiy match satisfies the heat duty on a stream or a utility. [Pg.370]

Following the pinch rules, there should be no heat transfer across either the process pinch or the utility pinch by process-to-process heat exchange. Also, there must be no use of inappropriate utilities. This means that above the utility pinch in Fig. 16.17a, high-pressure steam should be used and no low-pressure steam or cooling water. Between the utility pinch and the process pinch, low-pressure steam should be used and no high-pressure steam or cooling water. Below the process pinch in Fig. 16.17, only cooling water should be used. The appropriate utility streams have been included with the process streams in Fig. 16.17a. [Pg.381]

Normal Operation. The designer of a chemical plant must provide an adequate interface between the process and the operating employees. This is usually accompHshed by providing instmments to sense pressures, temperatures, flows, etc, and automatic or remote-operated valves to control the process and utility streams. Alarms and interlock systems provide warnings of process upsets and automatic shutdown for excessive deviations from the desired ranges of control, respectively. Periodic intermption of operations is necessary to ensure that instmments are properly caUbrated and that emergency devices would operate if needed (see Flow measurement Temperaturemeasurement). [Pg.100]

Figure 12.9 shows the temperature recording during the experiment A at the inlet and outlet of the reactor for process and utility streams. At t = 700 s, the reactor is fed with reactants instead of water. [Pg.279]

Two methods have been used to calculate the conversion rate in the reactor. They are based on thermal balances first between inlet and outlet of process and utility streams in the reactor and then between sampling and thermal equilibrium in the Dewar vessel. The former leads to the conversion rate obtained in the reactor, x and the latter gives the conversion rate downstream from the reactor outlet, 1 - X-... [Pg.279]

This approach consists in estimating heat exchanged by each stream in order to determine the heat provided to the system by the reaction. Actually, at steady state, the heat of reaction wiU lead to a temperature rise of process and utility streams, while the utility stream aims at limiting this increase (cooling effect). The conversion rate, x, is easily calculated by... [Pg.280]

Temperature difference in the reactor was less important than in the Dewar vessel because of the efhdent exchange with the utility stream. That is the reason error estimation in the reactor is higher than in the Dewar vessel. [Pg.280]

Finally, the oxidation reaction has to been run under strict conditions of temperature, which are impossible to be operated in a batch reactor. Indeed, utility stream in the Shimtec reactor was heated to 47 °C, which first initiates the reaction, accelerates its kinetics, and then controls the temperature when the heat of the reaction is too important. In a batch reactor, working with such UF temperature is impossible because of security constraints. It would certainly lead to a reaction runaway. We now consider this question in the next section. [Pg.281]

Comparison between the heat exchanged per unit of volume during oxidation experiment in the Shimtec reactor and the maximal heat exchanged in a classical batch reactor (with a double jacket) highlights the effectiveness of the former. Indeed, in oxidation reaction experiments, a mean value of the heat exchanged per unit of volume in the HEX reactor is estimated with utility stream temperature of 47 °C ... [Pg.281]

Then, the quantity of heat that could be removed in batch reactors whose volume varies from 11 to 1 m is calculated. In order to compare with experimental results, the temperature gradient is fixed at 45 °C (beyond which water in the utility stream would freeze and another cooling fluid should be used). The maximum global heat-transfer coefficient is estimated at an optimistic value of 500 W m K h The calculated value of the global heat transfer area of each batch reactor. A, is in the same range as the one given by the Schweich relation [35] ... [Pg.281]

Thickness of the wall between process and utility streams (m) Flow rate (kg s )... [Pg.284]

The next thing that is needed is a program that keeps track of all the process and utility streams, and determines the order in which the individual equipment calculations will be performed. This is sometimes referred to as the executive program. The user of this system has merely to put into computer language the flow diagram, which identifies the units (areas of heat exchangers, number of trays in a distillation column) and their interrelations, and to list the operating characteristics of each unit (the pressures, temperatures, exit compositions), the input variables to the plant... [Pg.418]

A hypothetical example of such a chart is shown below. All intended chemicals and common contaminants (such as utility streams that might leak in) are listed on both the horizontal and vertical axes. Each box in the chart represents the interaction of the two gridded components. Each half of the chart represents all possible binary (two-component) mixtures. Therefore, only one half of the matrix needs to be filled out to assess possible two-component combinations. This kind of simple analysis does not consider order of mixing (X mixing into Y is treated the same as Y mixing into X), which may be an important consideration such as when handling strong acids. [Pg.205]

Al) Energy balances on each hot process and utility stream in each temperature interval (TI) of the multiperiod MILP transshipment model. Each energy balance involves the residuals (heat cascaded) to and from the TI and the heat transferred in each stream match in the TI. [Pg.76]

A2) Energy balances on each cold process and utility stream in each TI. (A3) Zero residual to the hottest TI and from the coldest TI. [Pg.77]

The above overall heat balances state that the heat load of each process stream equals the sum of heat exchanged of that process stream with other process and utility streams. Note that the first subindex denotes the hot stream, the second the cold stream, and the third the stage. [Pg.367]

Operability The ability of a process to be regulated at desired operating conditions under uncertainty in feed or utility streams. [Pg.129]

The time constant of any process is the result of its capacitance and resistance. Usually, the heat exchanger outlet temperature is the controlled variable, and the flow rate of the heat transfer fluid is the manipulated variable. The time constant of an exchanger is a function of the mass and the specific heat of the tube material, the mass flow, and the specific heat of the process and utility streams and their heat transfer coefficients. [Pg.277]

The fewest exchangers usually needed is N-l, where N is the total number of both process and utility streams involved in the network. [Pg.67]

Minimum-Cost Network by the Thermodynamic (Minimum-Availability-Loss) Matching Rule. The thermodynamic matching rule states that "The hot process and utility streams, and cold process... [Pg.163]

Let us consider a CSTR/separator/recycle system, where the first-order reaction A —> P takes place. Figure 4.3(a) presents the conventional control of the plant. The fresh feed flow rate is kept constant at the value F0. The reactor holdup V is controlled by the effluent. The reaction takes place at a constant temperature, which is achieved by manipulating the utility streams. Dual-composition control of the distillation column ensures the purities of the recycle and product streams. [Pg.108]


See other pages where Utility stream is mentioned: [Pg.216]    [Pg.463]    [Pg.266]    [Pg.278]    [Pg.388]    [Pg.408]    [Pg.465]    [Pg.169]    [Pg.272]    [Pg.18]    [Pg.528]    [Pg.20]    [Pg.100]    [Pg.307]    [Pg.3]    [Pg.205]    [Pg.161]    [Pg.162]    [Pg.162]    [Pg.163]    [Pg.164]    [Pg.164]    [Pg.173]    [Pg.248]   
See also in sourсe #XX -- [ Pg.266 , Pg.278 ]




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