LPG CYLINDERS ROAD TRANSPORT SAFETY PROCEDURES BASICS AND TUTORIALS

Procedures for safe transport of LPG cylinders by road.

Transport
• Carry cylinders on open vehicles. Keep cylinders upright and adequately secured, e.g. with a rope.
• Keep a fire extinguisher, e.g. 1 kg dry power, in the cab to deal with any small fire, e.g. an engine fire.
• Do not leave cylinders on vehicles unsupervised.
• Ensure that the driver has received adequate training and instructions about the hazards of LPG, emergency procedures, driver duties, etc.
• Ensure that relevant information is readily available on the vehicle, e.g. on a clipboard in the cab. This written information, e.g. as a TREMCARD, should contain details of the nature of the load and the action to take in an emergency.

Duties of vehicle operator
• Check whether the Road Traffic (Carriage of Dangerous Packages, etc.) Regulations 1986 apply. Exceptions apply to cylinders <5 litres; cylinders which are part of equipment carried on the vehicles, e.g. burning gear, bitumen boilers; cylinders associated with vehicle operation, e.g. cooking, water heating.
• Ensure the vehicle is suitable, normally an open vehicle. Use of a closed vehicle should be restricted to a small number of cylinders with a load compartment having adequate ventilation.
• Ensure the driver has adequate information in writing, e.g. a TREMCARD.
• Ensure the driver is provided with adequate instruction and training and keeps necessary records.
• Ensure loading, stowage, unloading are performed safely. All cylinders should be packed, strapped, supported in frames, or loaded to avoid damage resulting from relative movement. Cylinders should be stowed with valves uppermost.
• Ensure all precautions are taken to prevent fire or explosion.
• Ensure suitable fire extinguishers are provided.
• Ensure the vehicle displays two orange plates if 500 kg of LPG is carried.
• Report any fire, uncontrolled release or escape of the LPG, to the appropriate authority.

Duties of the driver
• Ensure the relevant written information from the operator is always available during carriage. Destroy, remove or lockaway information about previous loads.
• Ensure loading, stowage and unloading are performed safely.
• Ensure all precautions against fire or explosion are taken during carriage.
• Display orange plates (when required) and keep them clean and free from obstruction.
• If >3 tonnes of LPG is carried, when the vehicle is not being driven, ensure parking is in a safe place or that it is supervised (by the driver or a competent person aged >18).
• On request provide appropriate information to persons authorized to inspect the vehicle and load.
• Report any fire, uncontrolled release or escape of LPG, to the operator.

SOLVENTS FOR COTTON BASIC INFORMATION AND TUTORIALS

Cotton Solvents
What can be used as solvents for cotton?

Cellulose is s oluble only in unusual and com plex s olvent systems. Solvents for cellulose are c entral to the rayon and cellulose film industries, but are also necessary for s olubilizi ng cotton for the determination of molecular weight and degree of polymerization ( DP) by chromatographic m ethods.

These solvents fall into several categories. The solvents discussed do not include processes w here cellulose is converted t o a derivative that i s subsequently dissolved in a nother m edium. For e xample, cellulose acetate i s solubl e in acetone, but this is not a solut ion of cellulose. H ow ever, t he viscose process that f orm s a cell ulose xanthate deri v at ive, f rom which c el lul ose is readil y regenerated, is gene rally c onsidered to use a cellulose solution because s olvation and derivatization oc cur simultaneously.

The viscose process is the most important method for m aking cellul ose solutions for industrial use. Alkali cellulose ( pulp s wollen in NaOH) i s pressed a nd aged to reduce m olecula r weight. Xanthation (a reaction with CS2 ) takes place in a vessel t hat c ontains an inert atmosphere (CS2 –air mixtures ar e explosive).

The orange xanthate i s s ubsequently dissolved in aque ous alkali to make the spinni ng dope. The dope is pumped t hrough spinnerets in which t here are f rom 14 t o 40,000 holes. The spun dope is converted back to c ellulose by the sulfuric acid i n t he coagul ating bath. Another s ystem with simultaneous derivitization and dissolution uses dimethyl sulfoxide and f ormaldehyde [ 133].

Several solvent s, such as cuprieth ylenedia mine (C UEN) hy droxide, de pend on the formation of metal–i on c omplex es with cellulose. Wh ile not as wi despread in use as the viscos e process , CUEN and its relative s with diff erent metals and ammoni um hyd roxide find substantial indust rial use [131]. The cad mium comp lex, cadoxen , is now the so lvent of choice in laborat ory work [134].

Aqueous salt solut ions such as satur ated zinc chloride or calci um thiocy anate can dissol ve limit ed amounts of cellulose [131] . Two nona queo us salt solut ions wi th a lengthy hist ory are ammoni um thiocy ana te=ammon ia and dimethylac etam ide =lithium chlori de (DMAc =LiCl). Soluti ons up to abou t 15% can be prepared with these solvent s. DMA c–LiC l has be en used for mo lecular weight determinat ions of cotton.

Trifluoroacet ic acid–m ethyl ene chlorid e and N -methyl mo rpholin e N -oxide mon ohydrate (NMMO) [136–138] are two other solvent systems that have been studied [139]. The new generic class of regenerated cellulose fibers, lyocell (e.g., Tencel [Courtaulds Fibres Limited, London, England]), is spun from aqueous solutions of NMMO [140].

Lyocell is an alternative to the generic name ‘‘rayon’’ for a subcategory of rayon fibers where the fiber is composed of cellulose precipitated from an organic solution in which no substitution of the hydroxyl group takes place and no chemical intermediates are formed.

Lyocell may have a different crystalline structure (a mixture of cellulose II and cellulose III [141]) than other rayons and cotton cellulose. No information has been published on cotton molecular weight determinations using NMMO as the solvent.

PLANT CAPITAL COST ESTIMATION VIA SCALING FACTOR

Given that the total capital investment (TCI) of a 50,000-ton/year polypropylene unit is $60,000,000 (in 2002 dollars), find the TCI required for a 75,000-ton/year polypropylene unit via the scaling factor method.

Calculation Procedure
1. Apply the appropriate power-function formula. In the scaling factor method, the TCI is estimated via the following formula (a power function):
TCI2 = TCI1(C2/C1)E
where TCI1 and TCI2 = total capital investment of existing and planned unit, respectively, in dollars
TCI1 = $60,000,000
C1,C2 = capacity of existing and planned unit, respectively, in tons/year
C1 = 50,000 and C2 = 75,000
E = scaling exponent = 0.70

Thus
TCI2 = 60,000(75,000/50,000)0.70 = $80,000,000 (rounded)

Related Calculations. The scaling factor method is an appropriate procedure for estimating the TCI only under the following conditions:

1. The existing and planned units are identical (or nearly so), in terms of processing steps, end products, major equipment items used, and other respects.

2. The desired estimate falls within the category of “order-of-magnitude/screening/scoping” cost estimates (i.e., those estimates with a presumed accuracy less precise than ±30%).

3. The capacity of the planned unit falls within the capacity range for which the scaling exponent is valid. Rarely is the power function relationship between TCI and capacity a smooth curve over the entire capacity range.

Typically, the scaling exponent increases in value with increasing capacity. However, as the scaling exponent approaches unity, it becomes less costly to build two units, each with half the capacity of the large plant, than to construct a single, large-capacity plant.

4. The costs of both the existing and planned units are expressed in dollars of the same period. In this example, the TCIs are in 2002 dollars. If the costs are not of the same vintage, the cost of the existing plant (which is likely older) will have to be adjusted to the same year dollars as that of the planned unit.

However, unless the cost vintages are much different (e.g., five years or more), adjustments for escalation would be “fine tuning,” compared to the relative inaccuracy of these scaling factor estimates.

DETERMINING THE LABORATORY-REACTOR SIZE NEEDED FOR SEEDING A BIOLOGICAL REACTION

SIZING OF BIO-REACTOR EXAMPLE AND TUTORIALS

Assuming a minimum 12% inoculum volume, what size of laboratory vessel would be required to initiate the seeding of a 20,000-L full-scale cell-culture bioreactor?

Calculation Procedure

1. Determine the size of reactor that would be required to seed the 20,000-L bioreactor. Since the seed volume must represent 12% of the vessel before reaction starts, the bioreactor being specified in this step would have to have a size 12% that of the 20,000-L bioreactor, or (0.12)(20,000), or 2400 L.

2. Determine the size of bioreactor needed to seed the 2400-L bioreactor of Step 1. Applying the same logic as in step 1, we see that the bioreactor being sought in this second step must be sized at 12% of 2400 L, or (0.12)(2400), or 288 L.

3. Repeat Step 2 successively until a bioreactor of reasonable laboratory volume is reached. Twelve percent of 288 L is 34.6 L; then, 12% of 34.6 is 4.15 L; and 12% of 4.15 L is 500 ml. Thus, a 4.15-L laboratory vessel can be used if available.

Otherwise, use a 500-ml vessel. The contents of the 500-ml vessel provide seeding for the 4.15-L vessel; the contents of the latter vessel then seed the 34.6-L bioreactor; the contents of this latter then seed the 288-L bioreactor; and so on.