US2694404A

US2694404A - Nitroglycerin transport

Info

Publication number: US2694404A
Authority: US
Inventors: Alexander V D Luft; Vincent H Waldin; Samuel E Walker; Philip G Wrightsman
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1952-09-24
Filing date: 1952-09-24
Publication date: 1954-11-16
Anticipated expiration: 1971-11-16

Description

N 1954 ALEXANDER v. d. LUFT EI'AL 2,694,404

NITROGLYCERIN TRANSPORT Filed Sept. 24, 1952 IN VENTORS ALEXANDER v. d. LUFT VINCENT H. WALDIN SAMUEL E. WALKER PHILIP G. WRIGHTSMAN ATTORNEYS 2,694,404 "NTTROGLYCERIN TRANSPORT Alexander v. d. Luft," Clarksboro, N.J. ,"'Vinc'ent"H. Waldin, N ewpo'rt, and Samuel E; Walker, Wilmington, Del., andiPhilip G; Wrightsman, Swarthmore,Pa.,"as- ""signors tdE. Isdu Pont de Nemours & Company,

Wilmington, Del., a corporation of'Delaw'are Application-September 24, 1952, Serial No. 311,246 3 Claims. (Cl. 137-1) -The :presentinvention relates to a-novel method and States Pateti't' O apparatus .fortransporting liquid'explosive nitric esters safely andefliciently.

Nitro'glycerin: is a highly sensitive liquid explosive-used in -the manufacture of commercial dynamite, and is prepared by the nitration'of glycerin. In the pure-liquid state, the sensitivity of the nitroglycerin is so great that evenminute disturbances may cause a detonation. For this-reason, it has long been the practice in the-explosive manufacturing industry to remove the nitroglycerin from the nitrator assembly as it is produced, and to store it in small quantities at widely scattered storage areas until thedyna'mite-mixing house is ready to use it immediately,-and-then to deliver the liquidnitroglycerin in small lots as it is used.

- The -dynamite-mixing houses are located a considerable distance from the nitrating apparatus to localizeany accidental detonation which may occur.

iWhile various methods for transporting nitroglycerin have been proposed, the most widely acceptedmeans has continued to be hand-pushed tank-carts having rubbertired Wheels and made of non-sparking materials. JBy design, these carts are capable of carrying only a very small quantity of the liquid explosive, and the runways provided for the carts must be maintained free of any obstruction and remote from any Work areas. Thus, this procedureis both costly and inelficient, and, in addition, requires repeated handling of the highly dangerous and unpredictable nitroglycerin.

Nitroglycerin, as the termis generally used in the industry, is not'restricted to'glycerol trinitrate, but includes also other explosive liquid nitric esters such as nitrated ethylene glycol, or various nitrated sugars such as glucose andsucrose. Frequently, a mixture of liquid explosive nitric :esters is prepared .by nitrating the raw materials together. Therefore, throughout this description, the terms nitroglycerin and liquid explosive nitric ester are interchangeable, and both terms include mixtures of liquid explosive nitric esters.

It is an object of the present invention to provide a safe and eificient method for transporting liquid explosive nitric esters without the use of manual means. A further object of the present invention is to provide apparatus adapted to accomplish the foregoing method of transporting liquid explosive nitric esters. Additional objects will become apparent as this invention is more fully described.

We have found that a liquid explosive nitric ester can be safely transported in pipes When it is first intimately mixed with water to form an emulsion, and the emulsion thus formed is transmitted through the pipe in relatively short columns separated by columns of water. A water emulsion of nitroglycerin is substantially incapable of being detonated, and by providing columns of water between columns of nitroglycerin in a pipe, absolute certainty is obtained that even if one column were detonated, for example, due to separation of the emulsion, the detonation would not be transmitted along the entire length of pipe.

To accomplish the foregoing method of transporting liquid explosive nitric esters, we use an eductor, wherein water under pressure creates a suction which draws either the ester or water into a mixing chamber within the eductor, and feeds the emulsion thus formed, or the water mixture into the transport pipe.

In order to more fully describe the present invention,

reference is 1 made i "to thei accornpanying 'tdrawing, Lin which:

Figure 1 is azrschematic. diagram 'of at nitroglycerin transport assembly in accordanceirwith thezapresentf invention;;and.

Figure; 2 is a" sectional-view carryout thepresentmethod. .1 In Figure 1,- 1lrepresents.a nit-ratoreasse'mbly, includingneutralizers and the 'preliminarywash apparatus,- 2 is a nitroglycerin reservoir, and-3 is-aswatenresetVoir. 4 representstheeducton fully detailed in Figure 2. an5zis a water-pumpt-assernbly, includingcontrol :valves; etc., to regulaterthe"pressure.andhmaintain ar'constant flow. 11-6 represents two air-operated valves, 7 represents axsource of air pressure, 8 represents a.solenoid operated valve adapted to regulate 'the" fiow' of air under pressure into or out of the air line to valves ,6, and 9' is a.timer-. controller adapted to regulate the operation of "solenoidoperated valve 8. 10 representsthe 'nitroglycerinItransport "pipe, 11 is' awater-return pipe, 12 is the. suction of van 'eductonadapted to tube, and 13 represents the water inlet tube from pump 5" to 1 eductor 4. P l4rirepresents anernulsion-brealcing separator assembly,..and. 15 represents a 'pipe from the separator 14 to the point .of utilization .ofm-the l-nitroglycerin.

In Figure 2, 4 :representsuthe. body ofnthe eductor wherein 16.is.an1'inlet.- tube havinga nozzle-17. =.The nozzle 17 PIOjGCtSi' into-the chamber 18 formed Iati'the junction of: suction tube 12 'withthebody .4. The'throat 20 in body 4-lies between the convergent'sexit.t2lxfrom chamber :18 and the divergent.exit:22Ileading.to.thertransport pipe 10.

:The operation :of the present .system is as follows: Water.under pressure. fromxpump 5 passesthrough -pipe 13 to the eductor-4, enteringthrough inlet tube 16xand nozzle. Due -to'thereduced opening. provided by. the

nozzle, the Water velocity. past the nozzle is considerably greater than the velocity in .pipe .13... The: highl-velocity stream of waterissuing from .nozzle 17 produces a reduced pressure area laroundathelnozzle in.chambent.:-18,

- thus 'drawing liquid through the suction .tube. 12, the

liquid thus drawn: depending :.upon. the positions. of valves 6.

Due to theturbulence in chamber 18, the liquid. drawn throughitubel 12 is intimately intermingled with: the water stream from nozzle 17; Where nitroglycerin is theliquid,

theintermingling produces. an aqueous emulsion; :lThe intermingled liquids enter the :transportpipe 10 via. the convergent. exit 21, the throat 20 and thedivergentexit 22,:additional turbulence beingpresentthroughout, and

breaking separator '14, where the separated nitroglycerin, having a higher specific gravity than water, is removed from the bottom through pipe 15, and the separated water is returned to pump 5 through pipe 11.

The level of nitroglycerin in reservoir 2 is maintained by flow from the nitrator 1, and the water level in reservoir 3 is maintained by either providing a return from pump 5 or by a fresh water source, neither being shown. Preferably, provision is made for purging the water system and introducing fresh water to pump 5.

Valves 6 are so adjusted that in the absence of air pressure, the valve in the nitroglycerin line is closed and the valve in the water line is open. When air pressure is applied, the valve in the water line closes and the valve in the nitroglycerin line opens, thereby providing for a fail-safe condition. Timer controller 9 can be adjusted to energize and de-energize the solenoid valve 8 at any desired frequency. Valve 8, in a deenergized position, vents the line to the valves 6, and in the energized position connects the line to the air-pressure source 7, thereby also creating a fail-safe condition. By the term fail-safe condition, We mean that in the event any of the mechanism fails to operate, the liquid being transported will be water, and there will be no accumulation of nitroglycerin at the receiving end, or a solid column of emulsion in the transport pipe 10.

The following example is presented only for the purpose of illustrating the present invention, and does not constitute the limitation thereof.

Using an arrangement substantially as illustrated in Figure 1, wherein the pipes '10, 11, 12 and 13 all had an inside diameter of 0.569 inch, the distance from the nitrator assembly 1 to the separator 14 was approximately 600 feet, and the suction lift was about 3 feet, the assembly had the capacity to deliver 700 pounds of nitroglycerin per hour using a water pressure from the pump of 30 pounds per square inch (gauge).

In the above assembly, the nozzle tapered at an angle of 7 to an inside diameter of 0.1575 inch, the convergent exit tapered at an angle of 15 to the throat, the distance of the throat from the nozzle being 0.72 inch. The throat had a diameter of 0.3 inch and a length of 0.4 inch. The divergent exit had a taper of 3.35%. Using these dimensions, the aqueous emulsion formed contained 43% nitroglycerin by weight.

The amount of nitroglycerin which can be delivered per hour using the present assembly .depends upon the following factors:

(a) Diameter and length of the transport pipe (b) Water pressure Eductor design and ratios (d) Suction lift distance (e) Length of emulsion column with respect to length of water column.

When a system has once been established, only factors (b) and (e) are readily variable, and therefore constitute the operational control of the present method. For maximum safety, we prefer to limit the length of the nitroglycerin column to not more than 75 feet, and the length of the water column to not less than 20 feet. The pressure at the eductor should be such that a transport line velocity of at least 3 feet per second can be maintained, the upper limitation on velocity being the capacity of the emulsion breaker-separator assembly. The length of the suction tube should preferably not exceed 8 feet for satisfactory operation. in order to reduce the danger of detonation the emulsion in the pipe should have a composition of not less than 30% water.

Preliminary separation of the emulsion may be obtained by simply enlarging the diameter of the pipe at the exit end of the transport line sufficiently to reduce the velocity of the mixture, thus reducing the turbulence. With a low line velocity, the emulsion is readily broken, and about fifteen feet of enlarged diameter pipe would be suflicient to facilitate rapid separation at the subsequent apparatus without requiring increased size thereof. Preferably, the transport pipe is made of material which is essentially not wetted by a liquid nitric ester, for example, polythene.

There are a number of critical ratios in the eductor design which must be met for efiicient operation. The nozzle must project past the center line of the chamber, and the taper angle lie between and 10 degrees. The distance from the tip of the nozzle to the throat is between 4 and 5 times the diameter 01' the nozzle, and the convergent exit angle is between 10 and 20 degrees. The ratio of the diameters of the nozzle and the throat determine, to a large extent, the composition of the emulsion, that is, the ratio of the water from the nozzle to the total liquid in the transport pipe is substantially the same as the ratio of the nozzle diameter to the throat diameter. Therefore, to maintain an emulsion containing at least 30% water; the ratio of the throat diameter to the nozzle diameter must be at least 1.2 to 1. The length of the throat lies in the range of from 1 to 1.5 times the diameter of the throat, and the divergent exit angle lies between 3 and 5 degrees.

The present invention can obviously be adapted to a fully automatic arrangement for the manufacture of dynamite. In such an arrangement, the timer-controller of the solenoid-actuated valve would be responsive to a control at the separator, thereby maintaining a constant level in the separator by regulating the respective column lengths of the nitroglycerin emulsion and the water. The nitrator assembly would be controlled so as to provide a predetermined level in the nitroglycerin reservoir. By thus integrating the operation, the storage of appreciable quantities of nitroglycerin would be completely avoided, and continuous operation assured.

It will be understood that many variations and modifications can be made without departing from the scope of the present invention. Therefore, we intend to be limited only by the following claims.

We claim:

1. A method for transporting liquid explosive nitric esters which comprises intimately intermingling said liquid explosive nitric ester with Water to form an emulsion, introducing said emulsion into a transport pipe to form a column within the pipe introducing water into said pipe to form an adjacent column within the said pipe, and so continuing to alternately introduce emulsion and water into said pipe at a pressure sufiicient to provide a flow of at least 3 feet per second through said pipe.

2. A method as claimed in claim 1, wherein the length of the emulsion column does not exceed feet, and the length of the Water column is not less than 20 feet.

3. A method as claimed in claim 1, wherein the emulsion has a composition of at least 30% water.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,835,603 Kincaid, Jr. Dec. 8, 1931 2,109,611 Axelrad Mar. 1, 1938 2,283,907 Berman May 26, 1942 2,379,240 Lobdell June 26, 1945

Claims

1. A METHOD FOR TRANSPORTING LIQUID EXPLOSIVE NITRIC ESTERS WHICH COMPRISES INTIMATELY INTERMINGLING SAID LIQUID EXPLOSIVE NITRIC ESTER WITH WATER TO FORM AN EMULSION, INTRODUCING SAID EMULSION INTO A TRANSPORT PIPE TO FORM A COLUMN WITHIN THE PIPE INTRODUCING WATER INTO SAID PIPE TO FORM AN ADJACENT COLUMN WITHIN THE SAID PIPE, AND SO CONTINUING TO ALTERNATELY INTRODUCE EMULSION AND WATER INTO SAID PIPE AT A PRESSURE SUFFICIENT TO PROVIDE A FLOW OF AT LEAST 3 FEET PER SECOND THROUGH SAID PIPE.