StartUp Procedure

An operating procedure for the pilot plant has been developed during commissioning and trial runs of the equipment. The procedure, outlined in Table 12.8, will continue to change as additional information is learned about the system and the specific quirks of the equipment are revealed. The crucial aspect of the operating procedure is safety and the necessity for common sense to be used at all times during the operation of the equipment is emphasised. The process fluids are potentially hazardous and care should be taken to avoid exposing the equipment to any ignition source before, during or after being operated.

Table 12.8 - Start-Up Procédure for the Reactive Distillation Pilot Plant

Step

Action Required

1

Check that all safety eauioment is available and operational before beginning to operate any equipment in the laboratory (see Table 12.9). Check that the compressed air pressure is at least 300 kPa via the regulator gauge. Ensure that someone knows of your intention to operate the pilot plant or will be present while it is being operated.

2

Start the extraction fan and air conditioning to ensure the laboratory air is turned over at an acceptable rate.

3

Fill the feed tank with the desired mixture of ethanol and hydrocarbon. A known volume of ethanol should be introduced via the screw cap. The drum should be sealed tightly before introducing hydrocarbon from the cylinders via the bottoms cooler. Stop the flow periodically to weigh the cylinder in order to record the weight of hydrocarbon introduced to the feed mixture.

4

Check the orientation of all ball valves to ensure that the bottoms product will be recycled to the feed tank and that no distillate will be collected. Align the three way valves to prevent the flow of hydrocarbon to or from the feed cylinders. All samples points should be shut. The level column isolation valves should be open. All control valves should be fully closed (note that the 'off position for the control valves is fully open).

5

Pressurise the column with nitrogen to 200 kPa and then depressurise to less than 10 kPa to reduce the oxygen partial pressure in order to prevent a flammable mixture forming inside the column. Repeat this step two further times if the column has recently been fully opened to the atmosphere.

6

Ensure that there is at least 20 L of feed available in the feed tank. Prime the pump, bleed any air from the pump vent and seal the vent when full of liquid. Check liquid flows from the pump drain. Check and clear (if necessary) the strainer on the pump discharge line.

7

Start chilled water flow to the bottoms cooler and condenser. Check the rotameter float is at or near the top of its range.

8

Turn on three phase power at the mains and switch on all instrumentation and equipment at the junction box.

9

Start the feed pump. Slowly open the bottoms control valve after the reboiler sump level reaches the middle of the level column. This ensures that the reboiler elements are fully covered. Adjust the bottoms control valve to maintain constant sump level near the top of the sight glass.

10

Turn the reboiler on and fix the voltage at approximately 180 V to bring the column towards operating pressure. Monitor the column temperature profile to determine when vapour has reached the condenser: the column temperature will increase as the vapour reaches that point; and the reflux temperature will decrease when condensation begins. Vent the distillate as vapour (to the product cylinders) for 5-10 minutes to purge the system of non-condensable gases.

11

Allow the liquid distillate volume to build up. Slowlv open the reflux control valve to introduce reflux to the column. This will initially destabilise the column temperature profile and pressure - allow the column to return to steady state.

12

Slowlv open the distillate control valve to control the column pressure at the desired value. Opening this valve too quickly will drain the distillate and stop the reflux flow.

13

Vary the reboiler voltage to control the feed split. Monitor via the column temperature profile. Refer to charts in the laboratory to estimate the bottoms composition from the temperature at a given pressure.

14

Adjust the reflux rate and compensate the column by changing the reboiler voltage and distillate control valve as required.

Table 12.9 - Safety Equipment

Item

Description

Requirements

1

Fire extinguisher

• valid expiration date

• suitable for hydrocarbon fires (e.g. dry COa)

• easily accessible

2

Exhaust fan

• operational

3

Air conditioning

• operational

4

Drain

• clear

5

Instrumentation safety covers

• mesh screens are in place

• no exposed wires

6

Power isolation switch

• location known

• easily accessible

7

• discharges outside laboratory

8

Safety shower and eye bath

• operational

• water is cool

9

First aid kit

• available in adjoining laboratory

Was this article helpful?

0 0

Post a comment