Water feed flow rate

Figure 21.29 Response of the two-CSTR system to 50% positive and negative changes in throughput (a) feed flow rate and setpoint (b) reactor temperatures (T, solid Tj, dashed) (c) water feed flow rate ( solid q 2 dashed, in %) (d) holdups (L, solid L, dashed).

Microstrainer for waste water applications, c/s including screen and mechanism but excluding chamber, influent and effluent constmction. FOB cost = 85 000 for a waste water feed flow rate = 155 L/s with n = 0.36 for the range 44-155 and n = 0.8 for the range 155-450. Complexity factor FOB screen and mechanism only, X 1,00 fully installed working module, X 12.3. 

D25. We wish to remove acetic acid from water using isopropyl ether as solvent. The operation is at 20°C and 1 atm (see Table 13-51. The feed is 0.45 wt frac acetic acid and 0.55 wt frac water. Feed flow rate is 2000 k A countercurrent system is used. Pure solvent is used. We desire an extract stream that is 0.20 wt frac acetic acid and a raffinate that is 0.20 wt frac acetic acid. 

D29. We are recovering pyridine from water using chlorobenzene as the solvent in a countercurrent extractor. The feed is 35 wt % pyridine and 65 wt % water. Feed flow rate is 1000 kg/h. The solvent used is pure. The desired outlet extract is 20 wt % pyridine, and the desired outlet raffinate is 4 wt % pyridine. Operation is at 25°C and 1 atm Equilibrium data are in Table 13-7. 

Check the ideal cut size of a settling tank used to remove silt from river water, the water being used as make-up water for the cooling system of a conventional coal-fired power station. The plan area of the tank is 1052 m, the water feed flow rate is 0.693 m /s, the density of the silt is 2600 kg/m, the density of water is 1000 kg/m and viscosity is 0.001 Ns/m. ... 

The problem of distillation control was addressed in Chapter 8. The issue now is how to control the reactor liquid level, the recycle tank liquid level, the recycle flow rate, the ethylene oxide feed flow rate, and the water feed flow rate. 

To test the weakness or robustness of this first control scheme, a measurement error is introduced to the flow controller manipulating the water feed flow rate. The water feed flow controller receives a signal that is too low. It adjusts the flow to meet the current set point, when in fact it is supplying excess water. The ethylene oxide flow... 

If a positive measurement error is supplied, then the flow sensor transmits a flow that is too large. Since the ethylene oxide controller is set up so that the set point is in a 1 1 ratio to the water feed flow rate due to the reaction stoichiometry, too much ethylene... 

This control scheme is more robust in the event of a disturbance. The flow rate of the stream to the recycle pump is controlled, preventing any increases in the recycle flow rate. The recycle tank level is controlled by the water feed flow rate. The reactor is still under level control by manipulating the flow rate of the liquid stream leaving the reactor. The ethylene oxide feed flow rate is also manipulated by a composition controller, which measures the exit composition of ethylene oxide from the reactor. This control scheme does not allow for excess ethylene oxide or for excess water in the system, and hence this system cannot snowball. 

To demonstrate this system s robustness, the same measurement error can be introduced to the water feed flow rate. The strip chart in Figure 10.8 shows an introduction of—5 kmol h error into the sensor transmitting a flow measurement to the water feed flow controller. 

A = 4.05 X lO " cm/(s-kPa)(4.1 X 10 cm/(s-atm)) and = 1.3 x 10 cm/s (4)//= 1 mPa-s(=cP), NaCl diffusivity in water = 1.6 x 10 cm /s, and solution density = 1 g/cm . Figure 4 shows typical results of this type of simulation of salt water permeation through an RO membrane. Increasing the Reynolds number in Figure 4a decreases the effect of concentration polarization. The effect of feed flow rate on NaCl rejection is shown in Figure 4b. Because the intrinsic rejection, R = 1 — Cp / defined in terms of the wall concentration, theoretically R should be independent of the Reynolds... 

Factors affecting RO membrane separations and water flux include feed variables such as solute concentration, temperature, pH, and pretreatment requirements membrane variables such as polymer type, module geometry, and module arrangement and process variables such as feed flow rate, operating time and pressure, and water recovery. 

The feed flow rates and the reactor and bath temperatures were monitored at five minute intervals. After five to six residence times, two samples of the reactor effluent were collected in 50 ml Erlenmeyer flasks containing approximately 20 ml of benzene saturated with water. Sufficient polymer solution was collected to give a 3.0 weight percent polymer solution. The samples were... 

Example 1.5. For a binary distillation column (see Fig. 1.6), load disturbance variables might include feed flow rate and feed composition. Reflux, steam, cooling water, distillate, and bottoms flow rates might be the manipulated variables. Controlled variables might be distillate product composition, bottoms product composition, column pressure, base liquid level, and reflux drum liquid level. The uncontrolled variables would include the compositions and temperatures on aU the trays. Note that one physical stream may be considered to contain many variables ... 

With multiple steadystates, the process outputs can be different with the same process inputs. The reverse of this can also occur. This interesting possibility, called input multiplicity, can occur in some nonlinear systems. In this situation we have the same process outputs, but with different process inputs. For example, we could have the same reactor temperature and concentration but with different values of feed flow rate and cooling water flow rate. 

In some situations it is very important to be able to increase the flow rate above the design conditions (for example, the cooling water to an exothermic reactor may have to be doubled or tripled to handle dynamic upsets). In other cases this is not as important (for example, the feed flow rate to a unit). Therefore it is logical to base the design of the control valve and the pump on having a process that can attain both the maximum and the minimum flow conditions. The design flow conditions are only used to get the pressure drop over the heat exchanger (or fixed resistance part of the process). 

The reverse osmosis membranes were tested in the standard experimental set-up (10). The experiments were carried out at three different pressures 17.4, 40.8 and 102 bars the corresponding sodium chloride concentrations were 3500 ppm, 5000 ppm and 29000 ppm. Before the reverse osmosis runs, membranes were thermally shrunk for 10 minutes in water and subsequently pressurized at 15-20% higher pressures than those used during the reverse osmosis experiments. A feed flow rate of 400 ml/mln was used giving a mass transfer coefficient k = 40 x 10 cm/s on the high pressure side of the membrane. 

Feed water salinity Feed flow rate Operating Pressure... 

A proposal is made to use a geothermal supply of hot water at 1500 kPa and 180°C to operate a steam turbine. The high-pressure water is throttled into a flash evaporator chamber, which forms liquid and vapor at a lower pressure of 400 kPa. The liquid is discarded while the saturated vapor feeds the turbine and exits at lOkPa. Cooling water is available at 15°C. Find the turbine power per unit geothermal hot-water mass flow rate. The turbine efficiency is 88%. Find the power produced by the geothermal power plant, and find the optimized flash pressure that will give the most turbine power per unit geothermal hot water mass flow rate. 

There are, however, some distinctive differences between the environmental and the other aspects of catalysis. Fust, the feed and operation conditions of environmental catalysts cannot be changed in order to increase conversion or selectivity, as commonly done for chemical production catalysts. Second, environmental catalysis has a role to play not only in industrial processes, but also in emission control (auto, ship, and flight emissions), and even in our daily life (water purifiers). Consequently, the concept of environmental catalysis is vital for a sustainable future. Last but not least, environmental catalysts often operate in more extreme conditions than catalysts in chemical production. There are also cases, such as automotive vehicles, where they have to operate efficiently for a continuously varying feed flow rate and composition. 

Fig. 42. Ti-resolved propagators for water flowing within the inter-particle space of a bed packed with ion-exchange resin ( ) and for water exchanging between inter- and intra-particle environments ( ) during the time scale of the transport measurement. Data are shown for a volumetric feed flow rate of 2inl,inin. to a column of internal diameter 20 mm. Reprinted from reference (J32) with permission from Elsevier, Copyright (2003).

Reverse-Osmosis Experiments. All reverse-osmosis experiments were performed with continuous-flow cells. Each membrane was subjected to an initial pure water pressure of 2068 kPag (300 psig) for 2 h pure water was used as feed to minimize the compaction effect. The specifications of all the membranes in terms of the solute transport parameter [(Dam/ 6)Naci]> the pure water permeability constant (A), the separation, and the product rate (PR) are given in Table I. These were determined by Kimura-Sourirajan analysis (7) of experimental reverse-osmosis data with sodium chloride solution at a feed concentration of 0.06 m unless otherwise stated. All other reverse-osmosis experiments were carried out at laboratory temperature (23-25 °C), an operating pressure of 1724 kPag (250 psig), a feed concentration of 100 ppm, and a feed flow rate >400 cmVmin. The fraction solute separation (/) is defined as follows ... 

It is necessary to obtain one or more computer projection printouts from RO plant manufacturers to ensure correct RO design with the best balance of variables (e.g., feed flow rate, brine reject water flow rate, recovery rates, flux rates, and maximum applied pressures). If, for example, flux rates on first-stage membranes are higher than the manufacturer s recommendations, membrane fouling is likely to occur. 

The evaporator was fed a mixture of methanol and water and operated at a temperature of 120 °C. Prior to coating the channels with a commercial CuO/ZnO/ ai2o3 catalyst (Synetix 33-5 from ICI), an alumina sol was coated as interface to the channel surface. The catalyst was reduced in 10% hydrogen in nitrogen at 280 °C prior to exposing it to the reaction mixture. Methanol conversion increased at S/C 1.1 from 55 to 90% on increasing the reaction temperature from 200 to 260 °C at 6 Ncm3 h 1 liquid feed flow rate. 

Problem. A mixture of methanol and water containing 40 mol per cent of methanol is to be separated to give a product of at least 90 mol per cent of methanol at the top, and a bottom product with no more than 10 mol per cent of methanol. The feed flow rate is 100 kmol h 1 and the feed is heated so that it enters the column at its boiling point. The vapour leaving the column is condensed, but not sub-cooled, and provides reflux and product. Since all the vapour from the column is condensed, the composition of the vapour from the top plate must equal that of the top product as well as that returned as reflux. 

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