Backpressure control system

A slipstream is fed from this loop to the POD system. Pressure in this circulating loop is controlled by means of a backpressure controller located in the return line to the top of the reactor. 

A typical setup for kinetic measurements is given in Fig. 8. Basically a feed, a reactor and an analysis section are required. Nowadays mass flow controllers for both liquid and gas result in stable molar flowrates, ideally for kinetic studies. Pressure controllers maintain a constant feed pressure for the flow controllers, while backpressure controllers maintain the pressure in the reactors. Various methods of product analysis are available and depend highly on the system under investigation. 

Data Acquisition and Control System. Computer-based system that controls all parameters of HPLC instrument (eluent composition (mixing of different solvents) temperature, injection sequence, etc.) and acquires data from the detector and monitors system performance (continuous monitoring of the mobile-phase composition, temperature, backpressure, etc.). 

Control systems also include features to protect the membranes and the feed pump. Pressure switches are used on the pump suction for low inlet pressure and on the discharge for high pressure. A pressure-relief valve is installed on the permeate line to prevent backpressure from damaging the membranes. Back pressure shouldn t be considered an option for the membranes. Check with the manufacturer to see limitations on the membranes... 

Figure 3.7 shows the results obtained in the batch process at 87 °C according to literature procedures [50]. A mixture of water and p-dioxane as a solvent system was chosen to allow for homogenous reaction conditions using a Pd(0) catalyst Reaction times of 8 and Ih were observed for bromo- and chlorobenzaldehyde, respectively, until the (nonisolated) GC yield reached about 90%. The maximum reaction temperature was limited in these experiments by the boiling point of the mixture at ambient pressure. The same reaction was performed in the MMRS, which was equipped with a backpressure controller, so that the reactor could be operated at elevated temperatures and pressures. Conditions could be achieved with temperatures above the boiling point of the mixture under ambient pressure, which are often referred to as superheated conditions. The setup allowed quick variation... 

While a bottom-supported vessel must divert when shallow gas is encountered, a floating vessel has the additional option of simply abandoning the well. This option has led to the use of riserless systems when drilling the surface hole. However, a dynamic kill provides the only means of controlling the well. A dynamic kill makes use of annular friction as well as a heavier mud to hold backpressure on the formation. If very short wellbores are involved, the dynamic kill rates are usually to large to be practical. A well being drilled with a riserless system is very likely to be lost if shallow gas is encountered. 

Figure 5.2.1. Simplified diagram of a Py-GC system (not to scale). The pyrolyser is schematized as a heated filament type. A piece of a deactivated fused silica line is passed through the injection port of the GC and goes directly into the pyrolyser. This piece of fused silica is connected to the column, which is put in the GC oven. The pneumatic system consists of (1) a mass flow controller, (2) an electronic flow sensor, (3) a solenoid valve, (4) a backpressure regulator, (5) a pressure gauge, and (6) septum purge controller. The connection (7) is closed when working in Py-GC mode, and connection (8) is open. (Connection (7) is open when the system works as a GC only.) Connection (9) is closed and connection (10) is open when the GC works in splitless mode (purge off). Connection (10) is closed and connection (9) is open when the GC works in split mode (purge on). No details on the GC oven or on the detector are given.

Gas and liquid are mixed before entering the reactor bed in a gas-liquid chamber 17 at the inlet of the reactor. The gas leaving the reactor flows through a condenser 18, where evaporated solvent is condensed, and then to the gas-liquid separator 19. The condensed solvent is collected in a separate buffer vessel 20 and returned to the reactor if necessary, the gas leaves the system through a backpressure valve controlling the pressure in the system. The volumetric flow of the effluent gas is measured with a gas meter 21. 

It is not surprising that fluids can be propelled by gravity [45], which provides a pulseless flow. The flow rate is highly dependent on backpressure effects that are difficult to control due to variations in temperature and fluid viscosity. Such systems are simple, inexpensive and do not contain any moving parts, leading to minimal implementation and... 

The high viscosity of concentrated sulfuric acid causes a fairly high backpressure, which was mandatory for residence times as short as possible. The homemade pilot plant continuous reaction system consisted of a static mixer and a residence time loop with a total volume of565 mb (Fig. 15.19). The maximum temperature of the whole system was limited to 60 °C, because it was foimd that the complete heat of reaction was liberated within one second during the flow through the static mixer. To control the reaction temperature in this scale correctly dimensioned heat sinks are mandatory. With these precautions the same results were obtained as before. Using this equipment over 200 kg of4-(phenyl)morpholin-3-one were nitrated within 50 h. 

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