# Cstr

Topics: Residence time, Fluid dynamics, Time Pages: 15 (3185 words) Published: April 19, 2013
ABSTRACT

In this experiment, our objectives are to examine the effect in a tubular flow reactor and to construct a residence time distribution (RDT) for both pulse input and step change. The first experiment is the effect of pulse input in a tubular flow reactor. Before the experiment was done, we need to do some general start-up process in order to get a better result and to avoid errors during experiment. After that, a constant flow rate was set up at about 700 ml/min. After that, both of the experiment was done and the conductivity values for both step change and pulse input at the inlet and outlet was recorded and tabulated.

Experiment 1: Effect of pulse input in a tubular flow reactor.

The inlet and outlet conductivity C(t) is recorded and tabulated. After that a graph of C(t) versus time was plotted. Then, we are able to calculate each of the distribution of the exit time E(t). The E(t) was calculated at a regular interval of 30 seconds. After that, the graph for E(t) versus time was plotted. Then, we are able to calculated the value of mean residence time, varience and skewness. The value is the tabulated.

Experiment 2: Effect of step change in a turbular flow reactor.

The inlet and outlet conductivity C(t) is recorded and tabulated. After that a graph of C(t) versus time was plotted. Then, we are able to calculate each of the distribution of the exit time E(t). The E(t) was calculated at a regular interval of 30 seconds. After that, the graph for E(t) versus time was plotted. Then, we are able to calculated the value of mean residence time, varience and skewness. The value is the tabulated.

INTRODUCTION

A tubular flow reactor is a vessel which the flow is continuous, usually at steady state. Besides, the flow an be configured so that the conversion of the chemicals and other dependent are functions of position within the reactor rather than time.

In a ideal tubular flow reactor, the fluids flow is as if they were solid plugs or pistons. Other than that, the reaction time is the same for all flowing material at any given tube cross section. Tubular flow reactors react in batch process which is providing initially high driving forces that is diminish as the reactions progress down the tubes. In the tubular flow reactor, a cooling coil and immersion heater are provide d inside the reactor to provide constant reaction temperature.

However, many turbulent flow reactor that used to conduct experiment did not act in ideal ways. In a tubular flow reactor, a pulse of traer is injected at the inlet would not undergo any dispersion as it passed through the reactor and would appear as a pulse at the outlet of the reactor.

Tubular flow reactors were commonly used for:
1. Continuous production
2. Homogeneous or heterogeneous reaction
3. High temperature reactions
4. Fast reactions
5. Large scale reactions

Residence time distribution (RTD) of a chemical reactor is the probability distribution function that describes the amount of time a fluid element could spend inside the reactor. Residence time distribution is measured by introducing a non-reactive tracer into the system at the inlet. The concentration of the tracer is changed according to a known function and the response is found by measuring the concentration of the tracer at the outlet. In general, the change in concentration can either be pulse or step. In this experiment, we are going to examine the effect of a pulse input or step change in a tubular flow reactor.

AIMS

Experiment 1: Pulse input in a Tubular Flow Reactor

1. To examine the effect of a pulse input in a tubular flow reactor. 2. To construct a residence time distribution (RTD) for the tubular flow reactor

Experiment 2: Step change in a Tubular Flow Reactor

1. To examine the effect of a step change in a tubular flow reactor. 2. To construct a residence time distribution (RTD) for the tubular flow reactor.

THEORY

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