what are three characteristics of a good solvent to use for refluxing

Reflux Condenser

Meanwhile, the reflux condenser installed in the elevation distillation column is used to remove the lost methanol, and the remaining FFA content in the last process can be recycled into the process system for reuse and the enzymes can be recycled in the reaction.

From: Biofuels and Bioenergy , 2022

Parameters and concepts

F. Reventos , in Thermal-Hydraulics of Water Cooled Nuclear Reactors, 2017

3.2.three.5 Reflux condenser mode

Reflux condenser fashion is a cooling mechanism that could occur in a PWR usually in defined phases of small-break LOCA (SBLOCA) ( Pretel, 1997). At a reduced inventory vapor is produced in the core and flows through the hot leg to SG U-tubes where it can condense, fall back to the vessel, and help absurd the core. The secondary side of the SG has to be agile (or at least full of water) to provide the condensing capability. As well, during such cooling mode counter current flow occurs in hot leg since vapor flows forward to the SG and liquid flows backward to the vessel.

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CONDENSERS

R.Westward. Serth , in Process Heat Transfer, 2007

11.ii.5 Reflux condenser

A reflux condenser, too called a vent condenser or knockback condenser, is a vertical tube-side condenser in which the vapor flows upward, as indicated in Figure eleven.7. These units are typically used when relatively small amounts of light components are to exist separated from a vapor mixture. The heavier components condense and flow downward along the tube walls, while the light components remain in the vapor stage and exit through the vent in the upper header. In distillation applications they are near oft used as internal condensers [4], where the condensate drains back into the elevation of the distillation column to supply the reflux, or equally secondary condensers attached to accumulators (Figure 11.8). These units have first-class venting characteristics, but the vapor velocity must be kept low to prevent excessive entrainment of condensate and the possibility of flooding. The fluid placement (coolant in shell) entails the aforementioned disadvantages equally the tube-side downflow condenser.

Effigy 11.seven. Reflux condenser

(Source: Ref. [1]).

Figure eleven.8. A reflux condenser used equally a secondary condenser on an accumulator

(Source: Ref. [4])

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Crude Stabilization

Maurice Stewart , Ken Arnold , in Emulsions and Oil Treating Equipment, 2009

2.3.4 Stabilizer Reflux System

A stabilizer reflux system consists of a reflux condenser, reflux accumulator, and reflux pumps. The system is designed to operate at a temperature necessary to condense a portion of the vapors leaving the top of the stabilizer. The temperature range tin exist determined by computing the overhead vapor's dew-point temperature. The heat duty required is determined by the amount of reflux required.

Selection of the blazon of exchanger for the reflux condenser depends upon the design temperature required to condense the reflux. The lower the operating pressure of the stabilizer, the lower the temperature required for condensing the reflux will be. In nearly installations, air-cooled exchangers may exist used. Other instances may require refrigeration, and a shell-and-tube-type exchanger will exist used.

The reflux accumulator is a ii-phase separator with several minutes of retention time to allow separation of the vapors and liquids. The reflux accumulator is normally located beneath the reflux condenser, with the line sloped from the condenser to the accumulator. The reflux accumulator must exist located to a higher place the reflux pumps to provide the necessary net positive suction head (NPSH) required by the pumps. The size of the reflux accumulator depends on the amount of reflux required and the full amount of vapors leaving the tower.

Reflux pumps are sized to pump the required reflux from the reflux accumulator back to the top of the stabilizer. Normally, these pumps are designed with a delta pressure of 50 psi (340 kPa). Depending upon the reflux apportionment rate, ii 100% pumps or three 50% pumps may be installed. This allows either a 100% spare or a fifty% spare pump.

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Debris bed hydrodynamics, convective heat transfer and dryout

Arun Nayak , Parimal Kulkarni , in Severe Accidents in Nuclear Reactors, 2021

9.4.iii.1 Tiptop flooding condition

Once the liquid starts boiling, the reflux condenser at the top is started which helps in maintaining a liquid pool on the top of the bed and no additional water is pumped in to the bed. The water flows down the bed past gravity and a counter current flow is established. Pressure drops are recorded once steady country is reached. Pressure drib is measured at diverse heating power in increasing social club below the dryout heat flux. As the heating power increases, the vapor velocity increases. It limits the inflow of the liquid. Dryout occurs at a particular vapor velocity when the counter current flooding limitation is reached. The vapor velocity is calculated every bit follows:

(9.2) $J_g\left(z\right)=\frac{\underset{0}{\overset{z}{\int }}\stackrel{{}^{″\prime }}{Q}\left(z\right)dz}{{\rho }_{\mathrm{chiliad}}{h}_{fg}}$

The experimental results are shown in Fig. nine.12. Equally seen in the figure, the ii phase force per unit area drop characteristic shows typical S shaped curve. Initially, at low vapor velocities, the pressure gradient is negative. It indicates the reduction in hydrostatic head of the h2o due to presence of a low density steam phase. The drag force between vapor and liquid plays important role in this region. As the vapor velocity increases, the elevate strength between vapor and droppings particles becomes dominating which leads to increase in pressure level gradient. At college vapor velocities (higher powers), the upflowing vapor creates resistance in the path of downcoming h2o resulting into lower cooling. At a item power when the vapor balances the inflow of water, dryout occurs. It can be seen that, due to dryout, as there is no water present in the porous medium, the pressure level gradient drastically reduces equally shown in Fig nine.12.

Figure ix.12. Measured force per unit area gradient at different heat flux conditions at 1 bar.

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Industry

Walther Grot , in Fluorinated Ionomers (Second Edition), 2011

Example 2

In a 100-ml four-necked flask equipped with a reflux condenser, a dropping funnel and a magnetic stirrer, which was purged with nitrogen gas, viii.24 g of sodium carbonate stale at 280°C for 2 h and forty ml of anhydrous diethyleneglycol dimethyl ether are charged.

The mixture is stirred and 20.0 g of vi-carboethoxy-perfluoro-2-methyl-3-oxa-hexanoyl fluoride of Comparative Example 1 is added dropwise at room temperature for 3 h.

Subsequently the addition, the stirring is connected for further i h and the solvent of diethyleneglycol dimethyl ether is distilled off. The remainder is stale at lxxx°C at 3 mmHg for 2 h to obtain 25.2 chiliad of a solid mixture of the object chemical compound having the formula

and NaF and sodium carbonate.

According to the analysis, the amount of the object compound is xx.3 g and the yield is 97%.

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Performance, combustion, and emission characteristics of DI diesel engine using mahua biodiesel

A. Santhoshkumar , ... R. Anand , in Advanced Biofuels, 2019

12.9.2.1 Esterification

The esterification process was performed on a hot plate which is equipped with reflux condenser, magnetic stirrer, and temperature controller. Mahua oil is initially heated at sixty°C for an hour to evaporate the moisture. Afterward that 1:6 ratio of methanol and 2   wt% of sulfuric acid were added one past 1 to the oil. Then the esterification was carried out for thirty   min on a hot plate with electrical power of 350   West at 55°C. After completion of the esterification process, the mixture is shifted to separating funnel and kept for 2   h to class two distinct layers. In these two layers, top layer consists of excess methanol, impurities goad and bottom layer contain esterified Mahua oil. The acid value of esterified Mahua oil is determined by titration method which is found to 0.8   mg KOH/g of oil.

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Scientific Bases for the Preparation of Heterogeneous Catalysts

P. County , ... N. Pernicone , in Studies in Surface Science and Catalysis, 2000

2.3 Catalytic measurements

Benzaldehyde hydrogenation was carried out in a glass batch reactor fitted with a reflux condenser, a mechanical stirrer and an external thermostating jacket [9]. The catalyst (corresponding to 4   mg Pd) was suspended in the solvent (100   ml ethanol) and pretreated in H_two menstruum (thirty   ml/min) at 80   °C for 1   h. After cooling to the reaction temperature (20   °C) benzaldehyde (1.0   ml) and n-octane (0.3   ml), used as internal standard, were added through a serum cap fitted to i arm of the reactor. The reactor was stirred at 1500   rpm and operated at atmospheric force per unit area in H₂ flow. The progress of the reaction was followed by gas-chromatographic analysis of samples withdrawn from the reaction mixture. The absence of external diffusion limitations was verified past preliminary runs performed under different stirring conditions.

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Introduction

Chuan Li , Xianguo Hu , in Biodiesel Soot, 2021

Experimental methods

The experiments were conducted in a 500-mL flask connected to a reflux condenser and the reaction mixture was agitated by a magnetic stirrer at 300 rpm. Ethanol and KOH calculated every bit per experimental design were blended and and so mixed with the cottonseed oil. The reaction mixture was heated to the reaction temperature when placed in an oil bath warmed at the reaction temperature. The reaction was stopped by removing the oil bathroom and adding 0.i mol/L hydrochloric acid as buffer solution. The upper-layer mixture was removed then purified. The yellow opaque liquid (i.e., biodiesel) was obtained later on neutralization, sedimentation, washing, filtration, and drying.

The glycerin content of the resultant mixture is equal to the conversion rate of triglycerides [86]. The glycerin yield (Eq. 1.i) was calculated using the following equation:

(1.1) $\text{One thousand}\left(\%\right)=\text{R}\text{One thousand}\left(\%\right)-\text{K}\text{K}\left(\%\right)$

where Chiliad (%) is the full yield of glycerin, RG (%) is the content of glycerin in the resultant mixture, and MG (%) is the content of glycerin in cottonseed oil.

The conversion rate of triglycerides can be calculated using the following Eq. (1.2):

(i.two) $\text{C}\text{o}\text{n}\text{5}\text{e}\text{r}\text{s}\text{i}\text{o}\text{n}\text{Inner space (0xEF07)}\left(\%\right)=\frac{\text{M}\text{1000}-\text{B}\text{K}}{\text{G}\text{One thousand}}\times 100\%$

where conversion (%) is the conversion rate of triglycerides; MG is the percent of glycerin ester in cottonseed oil; BG is the pct of glycerin ester in biodiesel.

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REACTION-KINETIC SYSTEMS

W. Fred Ramirez , in Computational Methods in Procedure Simulation (Second Edition), 1997

4.i CHLORINATION OF BENZENE

The chlorination of benzene produces monochlorobenzene, dichlorobenzene, and trichlorobenzene through the successive reactions

$\begin{array}{c}{C}_6{H}_6+C{\mathrm{fifty}}_2\stackrel{k_1}{\to }{C}_6{H}_{5}Cl+HC\mathrm{50}\\ C_6{H}_{5}Cl+C{l}_2\stackrel{k_{\mathrm{ii}}}{\to }{C}_{\mathrm{six}}{H}_{4}c{l}_2+HCl\\ C_6{H}_{4}C{l}_2+C{\mathrm{fifty}}_2\stackrel{{\mathrm{chiliad}}_2}{\to }{C}_6{H}_{3}c{l}_3+HCl\end{array}$

These reactions are carried out in a lead-lined or fe vessel, as shown in Effigy 4.1. Ferric chloride (FeCl _iii ) is used equally a catalyst. The vessel is fitted with cooling coils, since the reactions are exothermic. There is a reflux condenser, which returns vaporized chlorobenzenes to the organization, while assuasive the hydrogen chloride ( HCl) and backlog chlorine vapor to exit the system. In order to maintain the reacting mixture at a uniform temperature and to minimize mass transfer furnishings, the reacting mixture is well agitated. The corporeality of the chlorine gas which dissolves in the liquid phase is limited by the solubility of chlorine in the reacting mixture.

Figure 4.1. Reactor for Chlorination of Benzene

The following assumptions can exist made:

1.

There is no liquid or vapor agree–upward in the reflux condenser, i.eastward., no dynamics are involved.

2.

The system operates nether isothermal and isobaric weather condition.

3.

Volume changes in the reacting mixture are negligible.

4.

Hydrogen chloride vaporizes and leaves the system.

5.

In that location is negligible mass transfer resistance between the gaseous Cl _two and the Cl ₂ in solution, i.east., the Cl ₂ goes immediately into solution up to the solubility limit.

Commonly what is required is to know the time for (1) maximizing monochlorobenzene, (two) maximizing dichlorobenzene, and (3) maximizing trichlorobenzene.

We will presume that the feed rate of the dry out chlorine is 1.4 kg mol of chlorine per hr per kg mol of initial benzene charge. The following rate constants are estimated values for the catalyst used at 55°C (assumed for this problem):

$\begin{array}{c}{g}_1=510{\left(\text{kg}{\text{mol/m}}^3\right)}^{-1}{\left(\text{hr}\right)}^{-\mathrm{i}}\\ {\mathrm{grand}}_{\mathrm{two}}=64{\left(\text{kg}{\text{mol/m}}^3\right)}^{-\mathrm{ane}}{\left(\text{hr}\right)}^{-\mathrm{i}}\\ {\mathrm{1000}}_3=2.1{\left(\text{kg}{\text{mol/grand}}^3\right)}^{-\mathrm{i}}{\left(\text{hour}\right)}^{-\mathrm{ane}}\end{array}$

There is negligible liquid or vapor agree–upwardly in the reflux condenser. Volume changes in the reacting mixture are negligible, and the volume of liquid in the reactor remains constant at 1.46 thou³/kg mol of initial benzene charge.

Hydrogen chloride has a negligible solubility in the liquid mixture. The chlorine gas fed to the system goes into the liquid solution immediately up to its solubility limit of 0.12 kg mol of chlorine per kg mol of original benzene and this value and then remains constant. Each reaction is 2nd–gild as written.

The material balance for benzene is

where

N_B = moles of benzene

N_C = moles of chlorine

Five = volume of reactor

The material residuum for monochlorobenzene is

(4.one.2) $\frac{d{N}_G}{dt}=\frac{k_1{N}_B{N}_C}{V}-\frac{{\mathrm{thousand}}_2{\mathrm{Due\; north}}_K{\mathrm{Due\; north}}_C}{V}$

where N_Yard = moles of monochlorobenzene

The material balance for dichlorobenzene is

(4.one.3) $\frac{d{\mathrm{Northward}}_D}{dt}=\frac{{\mathrm{yard}}_2{\mathrm{North}}_{\mathrm{Grand}}{N}_C}{\mathrm{Five}}-\frac{g_3{N}_D{N}_C}{V}$

The textile residual for trichlorobenzene is

The material balance for chlorine is

(4.1.five) $\frac{d{N}_C}{dt}=F-\frac{{\mathrm{grand}}_1{N}_B{N}_C}{\mathrm{Five}}-\frac{k_{\mathrm{two}}{N}_{\mathrm{Grand}}{N}_C}{V}-\frac{{\mathrm{grand}}_3{N}_D{N}_C}{V}$

There is a maximum chlorine concentration of

where North _B0 = number of moles of benzene charged (which is 50 kg mol). Figure 4.2 presents the information–flow diagram for this arrangement.

Figure iv.2. Data–Flow Diagram for Chlorination of Benzine.

four.1.1 Society of Magnitude Analysis for Chlorination of Benzene

If the chlorination of benzene instance is to be solved using an IMSL integration routine, then the describing equations should offset be order–of–magnitude scaled. To exercise this nosotros want to create dimensionless variables of order one. For this problem we tin choose a characteristic concentration of Northward _B0 and a characteristic fourth dimension associated with the primary

reaction charge per unit $\tau =\frac{V}{{\mathrm{thou}}_1}.$ With these feature values the dimensionless variables of the problem are

$\begin{array}{cc}{N}_B^{*}=\frac{N_B}{N_{B0}}& N_T^{*}=\frac{N_T}{N_{B0}}\\ N_M^{*}=\frac{N_M}{N_{B0}}& N_C^{*}=\frac{N_C}{{\mathrm{North}}_{B0}}\\ {\mathrm{North}}_D^{*}=\frac{N_{D\mathrm{south}}}{N_{B0}}& t^{*}=\frac{t}{\tau }\end{array}$

Introducing these dimensionless variables, the describing differential equations become

(iv.one.8) $\frac{d{N}_{\mathrm{Yard}}^{*}}{d{t}^{*}}=N_B^{*}{N}_C^{*}-\frac{{\mathrm{yard}}_2}{k_1}{\mathrm{North}}_{\mathrm{Thousand}}^{*}{N}_C^{*}$

(4.1.9) $\frac{d{N}_D^{*}}{d{t}^{*}}=\frac{k_2}{k_{\mathrm{ane}}}{\mathrm{Due\; north}}_{\mathrm{One\; thousand}}^{*}{N}_C^{*}-\frac{k_{\mathrm{three}}}{k_{\mathrm{i}}}{N}_D^{*}{N}_C^{*}$

(4.1.10) $\frac{d{\mathrm{North}}_T^{*}}{d{t}^{*}}=\frac{k_3}{{\mathrm{grand}}_1}{N}_D^{*}{\mathrm{Northward}}_C^{*}$

(4.i.11) $\frac{d{\mathrm{Due\; north}}_C^{*}}{d{t}^{*}}=\frac{FV}{{\mathrm{chiliad}}_1}-N_B^{*}{N}_C^{*}-\frac{{\mathrm{thou}}_2}{k_1}{\mathrm{Northward}}_M^{*}{N}_C^{*}-\frac{k_{\mathrm{three}}}{{\mathrm{1000}}_{\mathrm{ane}}}{N}_D^{*}{\mathrm{Due\; north}}_C^{*}$

with

Substituting the given values into Equations 4.ane.7–(4.1.12) gives the following:

Equation 4.ane.seven stays the aforementioned, as

This implies that all terms in the benzene disappearance equation are of equal importance. Equation(4.1.8) becomes

(4.i.14) $\frac{d{\mathrm{Northward}}_M^{*}}{d{t}^{*}}=N_B^{*}{\mathrm{North}}_C^{*}-.1255N_M^{*}{\mathrm{North}}_C^{*}$

This implies that the disappearance term due to the monochlorobenzene is approximately one society–of–magnitude less important than the

generation term due to benzene. Both terms should be retained in the differential equation. Equation (four.ane.ix) becomes

(4.1.fifteen) $\frac{d{N}_D^{*}}{d{t}^{*}}=0.1255{\mathrm{Northward}}_{\mathrm{Thousand}}^{*}{N}_C^{*}-0.004118N_D^{*}{N}_C^{*}$

or

(4.1.sixteen) $7.97\frac{d{\mathrm{Northward}}_D^{*}}{d{t}^{*}}=N_M^{*}{N}_C^{*}-0.0328{\mathrm{North}}_D^{*}{N}_C^{*}$

Comparing Equation (iv.i.sixteen) to (4.1.xiii) or (4.1.14) shows that the dichlorobenzene response is approximately ane order–of–magnitude slower than that for the benzene consumption or monochlorobenzene generation response. Equation (iv.one.ten) becomes

(iv.1.17) $\frac{d{N}_T^{*}}{d{t}^{*}}=0.004118N_D^{*}{N}_C^{*}$

or

(4.1.xviii) $243\frac{d{\mathrm{Northward}}_T^{*}}{d{t}^{*}}=N_D^{*}{N}_C^{*}$

This implies that the trichlorobenzene response is approximately ii orders–of–magnitude slower than that for monochlorobenzene.

The problem is now ready for simulation. All terms should exist retained. Depending upon the information desired, the problem should be run between 10 to 100 dimensionless time units.

A MATLAB plan ex41.m has been created to solve this problem. The differential equations are divers in file model41.m. Results of running the problem are shown in Figure four.three. The maximum corporeality of monochlorobenzene occurs at 0.78 hours and that for dichlorobenzene at 1.75 hours.

Effigy 4.3. Results for Simulation of Chlorination of Benzene. Instance 4.i.

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Bones properties of biodiesel soot

Chuan Li , Xianguo Hu , in Biodiesel Soot, 2021

2.i.two.4 Synthesis of biodiesel

The weighted soybean oil was added into a 3-necked round bottom flask with reflux condenser and thermometer. According to a sure methanol/oil tooth ratio, methanol, soybean oil, and catalyst were placed in a vessel, and the reaction vessel was placed in a water bath under stirring. After the reaction, the goad was filtered in vacuum and recovered. The crude biodiesel was separated from the upper layer, and the biodiesel was separated from the crude biodiesel oil by vacuum distillation. Glycerol content was adamant past the potassium periodate oxidation method, since the conversion of glycerol reflects the conversion of biodiesel indirectly [2].

The formula for glycerol content (Eq. 2.1) is:

(2.one) $\mathrm{due\; west}\left(\%\right)=\frac{\left(V_0-V_1\right)\times \mathrm{1000}\times C}{4000\times m}\times 100$

Five ₀: the initial volume of Na₂S₂O₃ standard solution consumed, mL; Five _ane: book of Na₂South₂O₃ standard solution consumed in sample, mL; C: concentration of Na_iiS_twoO_iii standard solution, mol/Fifty; M: tooth mass of glycerol, thou/mol; thousand: mass of sample, g; w: glycerol content, %.

The formula for biodiesel yield (Eq. two.two) is given as:

(2.2) $Y\left(\%\right)=\frac{{\mathrm{1000}}_{\mathrm{i}}\times w}{m_2}\times 100$

chiliad _one: mass of crude glycerol, m; w: glycerol content, %; m ₂: theoretical mass of crude glycerol, one thousand; Y: biodiesel yield, %.

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