INSTRUCTION MANUAL

TUBULAR REACTOR

CET MKII

ISSUE 3 MAY 1997

ARMFIELD LIMITED

OPERATING INSTRUCTIONS AND EXPERIMENTS

CET Mkll REACTOR TUBULAR

Page No,

THE COSHH REGULA TIONS 1 INTRODUCTION 4 RECEIPT OF EQUIPMENT 5 DESCRIPTION 9 CONNECTION TO SERVICES 10 COMMISSIONING 12 OPERATIONAL PROCEDURES 14 EXPERIMENT SECTION 15 GENERAL SAFETY RULES a

THIS INSTRUCTION MANUAL SHOULD BE USED IN CONJUNCTION WITH THE MANUAL SUPPLIED WITH THE CEX Mkll CHEMICAL REACTOR SERVICE UNIT .

THE COSHH REGULATIONS The Control of Substances Hazardous to Health Regulations (1988) The COSHH regulations impose a duty on employers to protect employees and others from substances used at work which may be hazardous to health. The regulations require you to make an assessment of all operations which are liable to expose any person to hazardous solids, liquids, dusts, vapours, gases or micro-organisms. You are also required to introduce suitable procedures for handling these substances and keep appropriate records. Since the equipment supplied by Armfield Limited may involve the use of substances which can be hazardous (for example, cleaning fluids used for maintenance or chemicals used for particular demonstrations) it is essential that the laboratory supervisor or some other person in authority is responsible for implementing the COSHH regulations. Part of the above regulations are to ensure that the relevant Health and Safety Data Sheets are available for all hazardous substances used in the laboratory .Any person using a hazardous substance must be informed of the following: Physical data about the substance Any hazard from fire or explosion Any hazard to health Appropriate First Aid treatment Any hazard from reaction with other substances How to clean/ dispose of spillage Appropriate protective measures Appropriate storage and handling Although these regulations may not be applicable in your country I it is strongly recommended that a similar approach is adopted for the protection of the students operating the equipment. Local regulations must also be considered. Water-Borne Infections The equipment described in this instruction manual involves the use of water which under certain conditions can create a health hazard due to infection by harmful micro-organisms. For example, the microscopic bacterium called Legionella pneumophila will feed on any scale, rust, algae or sludge in water and will breed rapidly if the temperature of water is between 20 and 45C. Any water containing this bacterium which is sprayed or splashed creating air-borne droplets can produce a form of pneumonia cal1ed Legionnaires Disease which is potential1y fatal.

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Legionella is not the only harmful micro-organism which can infect water, but it serves as a useful example of the need for cleanliness. Under the COSHH regulations, the following precautions must be observed:- Any water contained within the product must not be allowed to stagnate, i.e. the water must be changed regularly. Any rust, sludge, scale or algae on which micro-organisms can feed must be removed regularly, i.e. the equipment must be cleaned regularly. Where practicable the water should be maintained at a temperature below 20C or above 45C. If this is not practicable then the water should be disinfected if it is safe and appropriate to do so. Note that other hazards may exist in the handling of biocides used to disinfect the water. A scheme should be prepared for preventing or controlling the risk incorporating all of the actions listed above. Further details on preventing inection are contained in the publication "The Control of Legionellosis including Legionnaires Disease" -Health and Safety Series booklet HS (G) 70.

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INTRODUCTION Tubular reactors are often used when operation without back-mixing is necessary .Often, they are referred to as Plug Flow reactors from the description of the way the reactants move through the tube. The Armfield CET MkII Tubular Flow Reactor is specially designed to allow detailed study of this important process. It is one of three reactor types which are interchangeable on the Reactor Service Unit (CEX MkII), the others being CEM MkII -Continuous Stirred Tank Reactor and CEB MkII -Batch Reactor. Reactions are monitored by conductivity probe as the conductivity of the reacting solution changes with conversion of the reactants. This means that the inaccurate and inconvenient process of titration, which was formally used to monitor the reaction progress, is no longer necessary.

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RECEIPT OF EQUIPMENT -1

1. SALES IN THE THE UNTTED KTNGDOM

. The apparatus should be carefully unpacked and the components checked against the Advice Note. A copy of the Advice Note is supplied with this instruction manual for reference. Any omissions or breakages should be notified to Armield Ltd within three days of receipt. 2 SALES OVERSEAS The apparatus should be carefully unpacked and the components checked against the Advice Note. A copy of the Advice Note is supplied with this instruction manual for reference. Any omissions or breakages should be notified immediately to the Insurance Agent stated on the Insurance Certificate if the goods were insured by Armfield Ltd. Your own insurers should be notified immediately arranged by yourselves.

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VIEW ON TOP

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DESCRIPTION See pages 6, 7 and 8. The reactor vessel (1) is set on a baseplate (14) which is designed to be located on four studs on the service unit and secured by the thumbnuts (15). The positioning of the reactor on the service unit is illustrated on page 3. NOTE: The reactor is.positioned on the service unit with non-return valve (11) on the left side of the reactor at the rear. The tubular reactor in which the chemical reaction takes place is a flexible coil (4) wound around an acrylic former. Total volume of the reactor coil is 0.4 litres. Reactants in the tube are maintained at constant temperature by circulation of water through the vessel from the hot water circulator of the service unit. Reactants are pumped from the two feed tanks by the peristaltic feed pumps and enter the reactor through connectors (6) and (7) in the lid of the vessel. Each reactant is pre-heated by heat transfer coils (2) and (3) before being blended together in "T" fitting (5). The reactants pass up through the reactor coil and leave the reactor vessel through the conductivity probe housing (16). This housing allows the conductivity probe (CP) to be held in the stream of reactants emerging from the reactor. Flexible tubing from the hose nozzle (10) is used to guide the reactants to drain. In order to maintain a constant temperature throughout the reactor coil, the coil bundle is submerged in circulating water which is automatically maintained at a pre-selected temperature by the temperature controller (TIC) in the console. The actual temperature of the circulating water and therefore the reactants is relayed to the controller by a sensing probe (TS) which is held in gland (8) in the lid. Water enters from the circulator at non-return valve (11) -this prevents water draining back through the priming vessel of the circulator when the pump is stopped. Water leaves the reactor at overflow (12) and returns to the circulator. Sockets in the side of the console pod of the service unit are provided to connect the conductivity probe and temperature sensor to the instrumentation in the console. These are of a different size so that the probes cannot be wrongly connected. When not in use, the reactor can be drained using valve (13) in the base.

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CONNECTION TO SERVICES When installed on the service unit, the following connections must be made to make the equipment operable:- Conductivity probe (Supplied with service unit) Place the glass conductivity probe (CP) in the housing (16) through the gland (9) provided. The gland may need to be loosened by hand before the probe can be inserted and can be tightened, again by hand, after insertion. The probe must be inserted as far as possible into the housing. NOTE: IT IS EXTREMEL y IMPORTANT TO ENSURE THAT THE PROBE IS INSERTED INTO THE HOUSING WITH THE ELECTRODE ACCESS HOLES IN THE GLASS SURROUND IN LINE WITH THE FLOW -OTHERWISE THE PROBE WILL GIVE SPURIOUS RESUL TS. Temperature sensor (Supplied with service unit) Place the temperature sensor (TS) in the reactor through the gland (8) provided in the lid in the same way as the conductivity probe. The probe must be inserted as far as possible into the reactor. Feed pump No.1 Each feed pump on the service unit is provided with an adequate length of flexible tubing for connection to the reactor inlets on the lid of the reactor. The end of the tubing is fitted with a plastic fitting which simply requires insertion to the connector (6) or (7) on the reactor. When these connectors need to be released, the plastic collar on the connector must be pushed by hand away from the tubing whilst simultaneously pulling the tubing nozzle out of the fitting. Feed pump No.2 See above. The pumps can be connected to either of the reactor inlet fittings. Hot water circulator The hot water circulator which is supplied with the service unit is equipped with flexible feed and return hoses that connect to the inlet and outlet of the reactor as shown in the diagram on page 8. It is important that the outlet in the base of the priming vessel, on the side of the hot water circulator, is connected "to the non-return valve

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connection (11) at the rear of the reactor. The hose is attached to the non- return valve using a quick release connector . The top flexible hose on the side of the hot water circulator is connected to the overflow (12) at the top of the water jacket on the reactor using a quick release connector . The lower flexible hose on the side of the hot water circulator is permanently connected to the inlet in the base of the priming vessel (stub pipe inside priming vessel). The bottom connection on the side of the circulator is a drain connection and is not used in normal operation. Chilled water circulator (Accessory CW-16 not supplied with standard unit) If it is required to operate the reactor at temperatures below ambient it is necessary to provide cooling water circulation in the reactor in the place of heating water. In this case the hot water circulator feed and return hoses are disconnected from the reactor and replaced with the feed and return hoses of the chilled water circulator. See the CW-16 instruction manual for further details.

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COMMISSIONING This procedure is intended as a method for ensuring that the equipment as received is fully operable and also to assist in familiarisation of the operator with the equipment. Water is used as the process liquid. [t is assumed that the reactor service unit (CEX) has been set up and commissioned in accordance with the instructions in the separate manual and that the reactor module has been mounted and connected to the appropriate services as detailed earlier in this manual. 1 half fill both reagent tanks with ambient potable water . 2 Set the temperature controller set point to 25C but do not switch on the hot water

circulator until the circulator and reactor water jacket have been primed as described below

3 If the hot water circulator has not been previously used it will be necessary to prime the

pump and heater inside the circulator as follows: Temporarily disconnect the top flexible hose on the side of the hot water circulator from

the overflow (12) at the top of the reactor water jacket. (To disconnect the hose, push the collar towards the Fitting while pulling the ferrule at the end of the hose.)

connect the free end of the hose to a clean cold water supply and allow the circulator to

fill until water appears in the priming vessel.

Disconnect the cold water supply then reconnect the flexible hose to he overflow on the reactor water jacket.

4 It is necessary to fill the reactor water jacket with cold water so that he overflow (12) is

covered. Loosen the gland (8) on the temperature sensor to allow air to escape when the water jacket fills. connect a flexible hose from a clean cold water supply to the drain valve (13) at the base of the reactor. Open the drain valve and allow he reactor water jacket to fill.

When the overflow is covered close the drain valve and disconnect he cold water supply.

5 Check that the fixings securing the lid of the reactor have been tightened. Also check that

the temperature sensor is installed and he sealing gland has been tightened. For safe operation, the hot

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water circulates at sub-atmospheric pressure and a leak will prevent the water from circulating.

6 Remove the lid from the priming vessel and pour water into the vessel until it is full to

the overflow. Switch on the circulator and immediately begin to pour the water into the priming vessel. Water will be pumped through the non-return valve (11) into the reactor and overflow through connection (12) back to the priming vessel which is designed to expel all of the air in the system. Continue to pour water into the priming vessel until all of the air is expelled. This is indicated by a level of water being established in the vessel and the absence of air bubbles in the flexible tubing.

IMPORTANT: Do not run the circulator dry as damage to the pump may occur. 7 Start the reagent feed pumps and set the pump speed control to 5.0. Water will begin to

flow from the feed tanks to the reactor and will be seen entering the reactor at the lid and begin to fill the reactor tubing as well as expelling air from the tubing

8 The reactor tubing will fill until the level reaches the overflow pipe in the conductivity

probe housing (16) and water will flow out of the reactor to drain. 9 Check that the temperature of the reactor contents (digital meter in console) is being

maintained at 25C. 10 Check that the conductivity meter is reading approximately zero. (Conductivity of tap

water). 11 Switch off the pumps and circulator. Drain the feed tanks

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OPERATIONAL PROCEDURES TEMPERATURE CONTROLLER Refer to the CEX service unit manual for details on controller operation and set up. It is possible to operate the reactor at temperatures above and below ambient using the hot water circulator (which is incorporated on the service unit) or the chilled water circulator accessory, CW-16.

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CET-MkII

EXPERIMENT SECTION INDEX

EXPERIMENT PAGE EXPERIMENT AL PROCEDURES I EXPERIMENT A A-1 To determine the rate constant using a tubular reactor EXPERIMENT B B-1 To investigate the effect of throughput on conversion EXPERIMENT C C-1 To demonstrate the temperature dependence of the reaction and the rate constant

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EXPERIMENTAL PROCEDURES The Armfield Continuous Tubular Flow Reactor is designed to demonstrate the mechanism of a chemical reaction in such a reactor as well as the effects of varying the process conditions such as reaction temperature, reactant concentration, feed rate etc. The reaction chosen is the saponification of ethyl acetate by sodium hydroxide as it can be carried out under safe conditions of temperature and pressure and is well documented. Although it may be possible to carry out demonstrations using other chemicals it is not advisable as the materials of construction of the reactor may not be compatible. Before carrying out reactions involving any other reagents please refer to ARMFIELD Ltd. For advice

Remove the lids of the reagent vessels and carefully fill with the reagents to a level approximately 50 mm from the top. Refit the lids. Adjust the set point of the temperature controller to 25C. Ensure that the thermostat on the side of the circulator is set to 30C. This will prevent the water in the circulator from overheating when first switched on. As the experiment involves the collection and storage of conductivity data, the data output port in the console must be connected to the CEX-90 IFD 3 (data logger) interface and the computer as detailed in the instruction leaflet supplied with the interface. This will enable data logging of the conductivity at selected time intervals over a selected period. Of course, if a computer is not available, the conductivity can be recorded manually at, say, half minute intervals by reading the value directly from the conductivity meter in the console. Ensure the conductivity probe and temperature sensor have been installed in accordance with the section CONNECTION TO SERVICES. Collection of data will be until a steady state condition is reached in the reactor and this takes approximately 30 minutes. It is advisable to set the data collection period to, say, 45 minutes. Using the calibration graph for each of the feed pumps, set the pump speed control to give 100 ml/min flowrate. Prior to priming the hot water circulating pump, it is convenient to fill the reactor with cold water up to the overflow (return to the circulator) using a suitable hose from a domestic supply through the temperature sensor gland (8) in the lid of the reactor. Non-return valve (11) prevents water flowing out of the reactor. Ensure the temperature sensor is re-fitted and the gland tightened securely by hand. Prime the pump as detailed in the OPERATIONAL PROCEDURES section of the CEX manual. Switch on the hot water circulator. The temperature of the water in the reactor vessel will begin to rise and will be automatically maintained at the desired set-point (25C in this instance). Switch on both feed pumps and instigate the data logger program ( or begin taking readings if no computer is being used). Reactants will flow from both feed vessels and enter the reactor through the connections in the lid. Each reactant passes through pre-heat coils submerged in the water in which they are individually brought up to the reaction temperature. At the base of the tubular reactor coil, the reactants are mixed together in a "T" connection and begin to pass through the coil. The reacting solution will emerge from the coil through connector (16) in

A-2

the lid where a probe senses continuously the conductivity which is related to degree of conversion. It has been determined that the degree of conversion of the reagents affects the conductivity of the reactor contents so that recording the conductivity with respect to time using the Armfield Data Logger can be used to calculate the amount of conversion. INTERPRETATION OF RESUL TS. Having used the Armfield Data Logger CEX-90 IFD3 to record the conductivity of the outlet of the reactor over the period of the reaction, the conductivity measurements must now be translated into degree of conversion of the constituents. Both sodium hydroxide and sodium acetate contribute conductance to the reaction solution whilst ethyl acetate and ethyl alcohol do not. The conductivity of a sodium hydroxide solution at a given concentration and temperature however, is not the same as that of a sodium acetate solution at the same molarity and temperature and a relationship has been established allowing conversion to be inferred from conductivity:- The calculations are best carried out using a spreadsheet such as LOTUS 123 or EXCEL so that the results can be displayed in tabular and graphical form. On conclusion of the experiment using the Armfield CEX-90 IFD3 data logger, a set of readings of conductivity with time will be stored in the computer . At this paint, this data can be transferred onto the spreadsheet. Start the spreadsheet program. Import the saved data onto the spreadsheet. For example, if using LOTUS 123, from the menu select PILE then IMPORT then NUMBERS then enter the file name of the saved data. Now enter the following known constants from the experiment using the Nomenclature list on page C2. Ensure use of correct units. Fa = Fb = a = b = c =

METHOD The experimental procedure is identical to that of Experiment A with the exception that flow rates of reactants can be varied to change the residence time of the reactants in the reactor - Simply calculate the degree of conversion of the reactants at steady state using conductivity readings (from data logger and spreadsheet as described in Experiment A) for different values of Fa and Fb. Experiment A used flows of 100 ml/min so it is suggested that flows of 40 ml/min and 70 ml/min are used for this experiment. Plot tR against Xa / (1- Xa) Comment on the graph obtained

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GENERAL SAFETY RULES 1 Follow Relevant Instructions a Before attempting to install, commission or operate equipment, all relevant

suppliers/manufacturers instructions and local regulations should be understood and implemented.

b It is irresponsible and dangerous to misuse equipment or ignore instructions, regulations or warnings.

c Do not exceed specified maximum operating conditions (e.g. temperature, pressure, speed etc.)

2 Installation a Use lifting tackle where possible to install heavy equipment. Where manual lifting is

necessary beware of strained backs and crushed toes. Get help from an assistant if necessary Wear safety shoes where appropriate.

b Extreme care should be exercised to avoid damage to the equipment during handling and unpacking. When using slings to lift equipment, ensure that the slings are attached to structural framework and do not foul adjacent pipework, glassware etc. When using fork lift trucks, position the forks beneath structural framework ensuring that the forks do not foul adjacent pipework, glassware etc. Damage may go unseen during commissioning creating a potential hazard to subsequent operators.

c Where special foundations are required follow the instructions provided and do not improvise. Locate heavy equipment at low level.

d Equipment involving inflammable or corrosive liquids should be sited in a containment area or bund with a capacity 50% greater than the maximum equipment contents.

e Ensure that all services are compatible with the equipment and that independent isolators are always provided and labelled. Use reliable connections in all instances, do not improvise.

f Ensure that all equipment is reliably earthed and connected to an electrical supply at the correct voltage. The electrical supply must incorporate a Residual Current Device (RCD) (alternatively called an Earth Leakage Circuit Breaker -ELCB) to protect the operator from severe electric shock in the event of misuse or accident.

g Potential hazards should always be the first consideration w hen deciding on a suitable location for equipment. Leave sufficient space between equipment and between walls and equipment.

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3 Commissioning a Ensure that equipment is commissioned and checked by competent member of staff before

permitting students to operate it. 4 Operation a Ensure that students are fully aware of the potential hazards w hen operating equipment. b Students should be supervised by a competent member of staff at all times when in the

laboratory .No one should operate equipment alone. Do not leave equipment running unattended.

c Do not al1ow students to derive their own experimental procedures unless they are competent to do so.

d Serious injury can result from touching apparently stationary equipment when using a stroboscope to 'freeze" rotary motion.

5 Maintenance a Badly maintained equipment is a potential hazard. Ensure that a competent member of

staff is responsible for organising maintenance and repairs on a planned basis. b Do not permit faulty equipment to be operated. Ensure that repairs are carried ot

competently and checked before students are permitted to operate the equipment. 6 Using Electricity a At least once each month, check that ELCB's (RCCB's) are operating correctly by pressing

the TEST button. The circuit breaker must trip when the button is pressed (failure to trip means that the operator is not protected and a repair must be effected by a competent electrician before the equipment or electrical supply is used).

b Electricity is the commonest cause of accidents in the laboratory. Ensure that all members of staff and students respect it.

c Ensure that the electrical supply has been disconnected from the equipment before attempting repairs or adjustments.

d Water and electricity are not compatible and can cause serious injury if they come into contact. Never operate portable electric appliances adjacent to equipment involving water unless some form of constraint or barrier is incorporated to prevent accidental contact.

e Always disconnect equipment from the electrical supply when not in use.

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7 Avoiding tires or explosion a Ensure that the laboratory is provided with adequate fire extinguishers

appropriate to the potential hazards. b Where inflammable liquids are used, smoking must be forbidden. Notices

should be displayed to enforce this. c Beware since fine powders or dust can spontaneously ignite under certain

conditions. Empty vessels having contained inflammable liquids can contain vapour and explode if ignited.

d Bulk quantities of inflammable liquids should be stored outside the laboratory in accordance with local regulations.

e Storage tanks on equipment should not be overfilled. All spillages should be immediately cleaned up, carefully disposing of any contaminated cloths etc. Beware of slippery floors.

f When liquids giving off inflammable vapours are handled in the laboratory I the area should be ventilated by an ex-proof extraction system. Vents on the equipment should be connected to the extraction system.

g Students should not be allowed to prepare mixtures for analysis or other purpose without competent supervision.

8 Handling poisons, corrosive or toxic materials a Certain liquids essential to the operation of equipment, for example mercury I

are poisonous or can give off poisonous vapours. Wear appropriate protective clothing when handling such substances. Clean up any spillage immediately and ventilate areas thoroughly using extraction equipment. Beware of slippery f1oors.

b Do not allow food to be brought into or consumed in the laboratory. Never use chemical beakers as drinking vessels.

c Where poisonous vapours are involved, smoking must be forbidden. Notices should be displayed to enforce this.

d Poisons and very toxic materials must be kept in a locked cupboard or store and checked regularly. Use of such substances should be supervised.

e When diluting concentrated acids and alkalis, the acid or alkali should be added slowly to water while stirring. The reverse should never be attempted.

9 Avoiding cuts and burns a Take care when handling sharp edged components. Do not exert undue force

on glass or fragile items. b Hot surfaces cannot in most cases be totally shielded and can produce severe

burns even when not 'visibly hot. Use common sense and think which parts of the equipment are likely to be hot.

10 Eye protecton a Goggles must be wom whenever there is a risk to the eyes. Risk may arise from powders,

liquid splashes, vapours or splinters. Beware of debris from fast moving air streams. Alkaline solutions are particularly dangerous to the eyes.

b Never look directly at a strong source of light such as a laser or Xenon arc lamp. Ensure that equipment using such a source is positioned so that passers-by cannot accidentally view the source or reflected ray.

c Facilities for eye irrigation should always be available. 11 Ear protection a Bar protectors must be wom when operating noisy equipment. 12 Clothing a Suitable clothing should be worn in the laboratory. Loose garments can cause serious injury

If caught in rotating machinery. Ties, rings on fingers etc. should be removed in these situations. Additional protective clothing should be available for all members of staff and students as appropriate.

13 Guards and safety devices a Guards and safety devices are installed on equipment to protect the operator. The equipment

must not be operated with such devices removed. b Safety valves, cut-outs or other safety devices will have been set to protect the equipment.

Interference with these devices may create a poteritial hazard. c It is not possible to guard the operator against all contingencies. U se common sense at all

times when in the laboratory. d Before starting a rotating machine, make sure staff are aware how to stop it in an

emergency. e Ensure that speed control devices are always set at zero before starting equipment. 14 First aid a If an accident does occur in the laboratory it is essential that first aid equipment is available

and that the supervisor knows how to use it. b A notice giving details of a proficient first-aider should be prominently displayed. c A 'short list' of the antidotes for the chemicals used in a particular laboratory should be

prominently displayed.

INSTRUCTION MANUALCET MKIIISSUE 3

MAY 1997CET Mkll REACTOR TUBULARVIEW ON TOPHot water circulatorOPERATIONAL PROCEDURESEXPERIMENT AA-1EXPERIMENT BB-1

A-2Fa=Comment on the graph obtained

B-29Avoiding cuts and burns