US2891563A

US2891563A - Production of explosives

Info

Publication number: US2891563A
Application number: US373493A
Authority: US
Inventors: Smith Kenneth Ashbrooke
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1952-09-19
Filing date: 1953-08-11
Publication date: 1959-06-23
Anticipated expiration: 1976-06-23

Description

June 23, 1959 i s rr 2,891,563

PRODUCTION OF'EXPLOSIVES Filed Au 11, 1953 2 Sheets-Sheet 1 FIG. 2.

I N VE N TO R Jfennei'h Ashbmpke mith,

W WJ ATTORN E Y5 June 23, 1959 K. A. SMITH 2,391,563

PRODUCTION 0 EXPLOSIVES Filed Aug. '11, 1953 2 Sheets-Shh 2 I 52 54 42 as I8 49 FIG. 5

INVENTOR.

Kenneth Aabb kesmah,

ATTORNEYS.

United States Patent 2,891,563 PRODUCTION or EXPLOSIVES Kenneth Ashbrooke Smith, West Kilbride, Scotland, assignor t0 Imperial Chemical Industries Limited, a corporation of Great Britain Application August 11, 1953, Serial No. 373,493

Claims priority, application Great Britain September 19, 1952 9 Claims. (Cl. 137-1) The present invention relates to improvements in or relating to the transporting of liquid explosive nitric esters of polyhydric alcohols for example nitroglyc'erine, nitropolyglycerine, ethylene glycol dinitrate and diethylene glycol dinitrate.

It is frequently necessary to transport these liquid ex-' plosive nitric esters for long distances, as for example, in the production of explosive compositions containing liquid explosive nitric esters. The hazard in carryng out transportation by a pipeline is that if an explosion is initiated at any point therein it is likely to be transmitted along the whole length of the pipe. Various methods have been adopted in attempts to overcome this hazard,

for example, nitroglycerine or ethylene glycol dinitrate,

or a mixture of these two esters has been transported as an emulsion with Water. This method is satisfactory, but

involves the additional steps of making and breaking an. emulsion and these additional steps are not without hazard. Anothermethod which has been adopted is to provide in the pipeline a number of syphoning arrangements of differing capacities so that at no time is there a continuous mass of explosive liquid throughout the system. This method also suffers from a number of disadvantages.

From general and fundamental principles underlying and governing the behaviour of explosives it was thought that a tube carrying a liquid explosive nitric ester should have a maximum diameter below which propagation of detonation becomes impossible however intense the source of detonation. It was experimentally ascertained that a tube carrying a liquid explosive nitric ester has such a maximum diameter and that it is about 0.1 inch and that the actual upper limit depends inter alia on the number of narrow bored tubes used to divide the path of flow of the liquid nitric ester, the material of the tubes and the nature of the surrounding material for the tubes, e.g. whether the tubes are surrounded by air or are immersed in a solid medium. To achieve adequate rate of flow it was clear that the number of narrow bored tubes used in any one set to form a multi-divided path for the liquid ester would usually have to be at least 10. Also it Was clear that to prevent flash over it would be necessary in practice for the set of narrow bored tubes to be at least 3 feet in length. Furthermore as it was known that to apply a pressure of more than 20 times an existing pressure on a bulk of liquid explosive nitric ester may produce an explosion in said bulk due to adiabatic compression of occluded air bubbles in the nitric ester (Detonation of Liquid Explosives by Impact, Nature, vol. 157, p. 105, Jan. 26, 1946. F. P. Bowden, M. F. R. Mulcahy, R. G. Vines, A. Yoife) it Was clear that the forcing pressure to be applied to force the liquid explosive nitric ester through any one set of tubes each of diameter not greater than 0.1 inch has to be less than 20 times the pressure on the ester before the application of this forcing pressure.

According to the present invention the method of transporting a liquid explosive nitric ester comprises forcing said liquid under a forcing pressure less than 20 times "ice the pressure on the ester before the application of this forcing pressure through at least one set of tubes of pressure resisting material not aifected by said liquid explosive, arranged to form a multi-divided path for the ester and each of at least 3 feet in length and internal diameter not greater than 0.1 inch.

The phrase pressure resisting materia includes steel but preferably the material for the tubes is based on natural or synthetic rubbers or thermoplastic resins such as polyethylene, polyvinyl chloride, synthetic linear polymers and the like.

The number of small bore tubes required in a section of the pipeline will be determined by the required rate of delivery and pressure of the explosive ester and may, for example, vary from 10 to 400.

The bore of the tubes may in some instancesbe considerably less than 0.1 inch. Furthermore, since tubes 7 made of materials like rubber, neoprene or polyethylene may undergo an increase in bore while in use because of the pressure necessary to force the liquid therethrough, it is preferred to have a bore of not more than 0.09 inch. The thickness of the tubes should be sufficient to enable them to withstand the working pressure and will, of course, vary according to the properties of the material from which the tubes are made.

If desired any set of small bore tubes may be enclosed in steel tubing or other conduit material while it'passes through obstructions, for example, such as blast walls. Sometimes it is desirable to fill the conduit with water or other non-flammable fluid to prevent the passage of a .flame or other disturbance external to the trap causing propagation of an explosion through the conduit. The use of enclosing conduits is not, however, desirable where the small bore tubes carry the explosive liquid across an open space.

The small bore tubes may be of any convenient length, for example, from at least 3 feet up to feet or longer. Thus they may be of the length required to carry the explosive liquid through the blast wall or mound which is positioned outside the building to or from which it is being transported or they may be longer. The small bore tubes may also be used to replace the section of pipeline passing through the partition between two compartments in the same building or in any other convenient'position where it is desired to stop propagation of an explosion; Thus, for example, their use is highly advantageous at the end of a pipeline for feeding the explosive ester into a mixer for the continuous mixing of explosive compositions and for this purpose the small bore tubes can be made of differing lengths so that the explosive liquid can enter the mixer at various points.

The pressure used to force the explosive ester through the tubes will depend on the length of the small bore tubes through which the liquid explosive ester has to be passed and on the pressure which the tubing will withstand without rupture. The working pressure may be obtained in one stage or a number of stages. Care must be taken, however, as previously stated that the compression ratio for any stage is always less than 20 to 1 so as to prevent the possibility of an explosion b-y adiabatic compression of air contained in the explosive ester. The liquid explosive nitric ester which is forced through a set of narrow bore tubes may have additional pressure applied to the liquid by means of a pump which may be for example a multi-cylinder gas operated diaphragm pump as disclosed in Patent No. 2,821,930 in order to force the liquid through a further length of a set of narrow bored tubes. The inlets and outlets for the pump may be in the formof a multiplicity of small bor'e tubes if desired. 1 i

A further advantage of the invention is that if a pulsating supply of liquid explosive nitric ester is fed for exam- 3 pie, from a pump, to the small bore tubes of any one set of elastically deformable material the pulsations are evened out and a continuous flow of ester is given at the exit end of the tubes.

In the following table the first part shows examples of the use of tubing suitable for the practice of the present invention and the second part shows the use of unsuitable tubing. The tubes were filled with a nitrated mixture of glycerol and ethylene glycol (ratio 80:20) and explosions were initiated outside the tubes at one end to determine Whether the explosions would be propagated beyond the other end of the tubes.

through a set of 30 neoprene tubes 16, each one having an internal bore of 0.09 in. and each being 75 ft. long. These neoprene tubes 16 lead the liquid explosive nitric ester mixture directly into a mixing machine 17. The delivery of the liquid explosive nitric ester from tubes 16 is in the form of droplets at a uniform rate of 4 lbs/minute.

The pressure of 3 atmospheres which is applied to the liquid explosive mixture in tank 3 is suflicient to force the liquid into the diaphragm portion 18 of the gas perated diaphragm metering pump 15.

Referring to Fig. 2 the set of neoprene tubes 4- en- Wall Length Number Propaga- Materlal thickness (feet) of tubes Confined or not tiou (inches) Polyethylene s 0.060 0.060 6 D0 0. 0.03 6 l 0. l9 0. 06 6 1 N0 0.070 0.08 6 14 Yes: in 1% steel No.

tubing. 0.085 0406 3 14 No No. 0.085 0.06 3 14 Yes: in 2% pipe No. 0. 070 0.08 4 19 Yes: in 1% tube No. 0.070 0.08 4 Yes: in water No.

filled 1% steel tube. 0. 085 0.06 4 16 Yes: in 1% steel N0.

tube. 0.080 0.035 3 4 N0 NO. 0.080 0 035 3 8 Yesrbin steel N0.

tn e. 0. 0625 0.0625 4 4 Yes: in steel No.

tubing. 0 091 0.035 4 9 Yes: in water No.

filled tube. 0.080 0 035 3 Q N0.

Steel 0.03 0.10 4 1 NO. Polyethylene 0. 125 0.06 6 4 Yes. Neoprene 0. 105 0. 035 4 7 Yes. Rubber 0. 144 0. l0 4 1 Yes.

The invention is illustrated by the following example and with reference to the diagrammatic drawing attached hereto in which Fig. 1 is a schematic view of a layout suitable for carrying out the method of the invention for transporting a nitrated mixture of glycerol and ethylene glycol (ratio 80:20) from a container in a nitroglycerine wash house to a mixing machine 300 ft. away into which the nitrated mixture is metered and mixed with the other ingredients required for the production of blasting explosive compositions, Fig. 2 is a crosssection on an enlarged scale of a set of narrow bored tubes enclosed in a wider tube, and Fig. 3 is a partly cross-sectional and partly schematical view on an enlarged scale of a gas operated diaphragm metering pump of the kind disclosed in Patent No. 2,821,930.

A nitrated mixture of glycerol and ethylene glycol (ratio 80:20) is contained in a tank 1 in a wash house. From tank 1 the nitrated mixture flows under gravity through valve 2 to tank 3 wherein it is subjected to a pressure of 3 atmospheres and is thus forced through a set of 30 neoprene tubes 4 each one having an internal bore of 0.09 in. and each being ft. long. The set of tubes 4 pass through a protective mound 5. The portion of this set of tubes 4 which is within the mound 5 is enclosed in a polyethylene tube 6 of 1 /2 in. bore through which brine is circulated. The liquid explosive nitric ester then continues its travel through a polyethylene tube 7 of A in. bore by Way of a coupling unit 8. The polyethylene tube 7 is underground and passes under small protective mounds 9 and 10 and then to a coupling unit 11 for connection to another set of neoprene tubes 12 each one having an internal bore of 0.09 in. and each being 25 ft. long. This set of tubes 12 passes through a protective mound 13. The portion of this set of tubes 12 which is within the mound 13 is enclosed in a polyethylene tube 14 of 1 /2 in. bore through which brine is circulated. This set of tubes 12 conducts the liquid explosive nitric ester mixture directly into a gas operated diaphragm metering pump 15 from which the liquid explosive nitric ester mixture is pumped directly closed in a neoprene tube 6 is shown in cross section on an enlarged scale.

Referring to Fig. 3 wherein the gas operated diaphragm metering pump 15 is shown on an enlarged scale partly in cross-section and partly schematically 19 is a gas distribution valve shown schematically which can rotate in a closely fitting housing (not shown) and is connected to a diaphragm portion 18 shown in vertical cross-section. The gas distribution valve 19 comprises a rotatable cylinder one half of which is so constructed as to permit the distribution of gas pressure and the other half is so constructed as to permit the release of gas pressure to the atmosphere. The half which permits distribution of gas pressure is provided with part

circumferential grooves

20 and 21 and the other half which permits release of gas pressure is provided with part

circumferential grooves

22 and 23. The close fit of'the housing round the rotatable cylinder in effect converts these

circumferential grooves

20, 21, 22 and 23 into ducts positioned and rotating Within the housing. The housing has six

ducts

24, 25, 26, 27, 28 and 29. During a portion of the revolution of the distribution valve 19 groove 20 communicates with duct 24 and during another portion of its rotation with duct 26 and in one stage of

rotation ducts

24 and 26 are in communication with each other through groove 20, but this is of no significance. Similarly groove 21 communicates with duct 27, groove 22 with duct 28 and groove 23 with duct 25 or duct 29. Ducts 2S and 29 are never in communication with each other through groove 23 and axial duct 30 is always in communication with groove 20 through ducts 31 and with groove 21 through ducts 32. Another axial duct 33 is always in communication with groove 22 through ducts 34 and with groove 23 through ducts 35. The axial duct 30 can be connected to a gas supply through a pipe 36 by way of a reducing valve 37 which controls the gas pressure to be delivered to the gas distribution valve 19 to a pressure less than a predetermined maximum pressure which is to be greater than the pressure which is to be applied to the liquid to be introduced into the diaphragm portion 18. duct 33 is open to the atmosphere.

The diaphragm portion 18 contains

cavities

38, 39 and 40. Cavity 38 has a diaphragm 41. Cavity 39 has a diaphragm 42 and cavity 40 has a diaphragm 43. Cavity 38 is connected by pipe 44 to

ducts

26 and 29, cavity 39 is connected by pipe 45 by

ducts

27 and 28 and cavity 40 is connected by pipe 46 to

ducts

24 and 25.

Liquid inlet 47 communicates with cavity 39 through

ducts

48 and 49 except when diaphragm 41 in cavity 38

seals ducts

48 and 49. Similarly the liquid outlet 50 communicates with cavity 39 through

ducts

51 and 52 except when diaphragm 43 in cavity 40 seals 01f

ducts

51 and 52.

Ducts

49 and 52 are at all times in communication. 53, 54 and 55 are surge preventing ducts.

The capacity of the liquid collecting chamber 39 is 6 ml. and the capacity of each of the

valve chambers

38 and 40 is 1.5 ml. The speed of rotation of the gas distribution valve 19 can be varied as desired. A convenient rotational speed is 30 revolutions per minute.

The metering pump as illustrated shows it in a position about to commence the discharge of liquid. The liquid at the outlet 50 is subjected to a back pressure due to the small bore tubing in the path of the discharge liquid in accordance with the process of the invention.

As duct 26 is in communication with groove 20 and so with the air supply and since duct 29 is sealed air pressure is applied to diaphragm 41 sealing off

ducts

48 and 49.

Ducts

27 and 24 are sealed of1 from the air supply and

ducts

28 and 25 are open to the atmosphere through

grooves

22 and 23 and therefore there is no air pressure on

diaphragms

42 and 43. The liquid collecting chamber 39 is full of liquid and the outlet valve diaphragm 43 is in position to permit communication between

ducts

52 and 51. After the gas distribution valve 19 has rotated slightly duct 27 is brought into communication with groove 21 and duct 28 is sealed off. Air pressure is thus applied to diaphragm 42 which moves so as to force the liquid from chamber 39 through

ducts

52 and 51 to the outlet 50. Further rotation of the gas distribution valve 19 leads to the opening of duct 24 to air pressure and the sealing of duct 25 and thus to the application of air pressure to diaphragm 43 causing this diaphragm 43 to move so as to force liquid from outlet valve chamber 40 through duct 51 to the liquid outlet 50 and then to seal duct 52 from duct 51. On further rotation of the gas distribution valve 19 duct 26 is sealed off and duct 29 is opened to the atmosphere thereby permitting liquid under pressure to move from liquid inlet 47 through duct 48 to move diaphragm 41 to fill inlet valve chamber 38 and to communicate with duct 49. As soon as duct 27 is sealed off and duct 28 opened to the atmosphere this liquid pressure enables liquid to flow through the inlet valve chamber 38 through duct 49 to fill the liquid collecting chamber 39 thereby moving diaphragm 42 to the position shown in the diagrammatic drawing. Further rotation of the gas distribution valve 19 seals duct 29 and so permits gas pressure through duct 26 and pipe 44 to actuate diaphragm 41 and to force liquid from inlet valve chamber 38 through the duct 48, back into the liquid inlet 47 and then to seal duct 49 from duct 48. In a further stage of rotation of the gas distribution valve 19 this valve is again in a position shown in the drawing when there is a release of pressure from diaphragm 43. Liquid from the outlet 50 subjected to a back pressure moves through duct 51 to fill outlet valve chamber 40 moving diaphragm 43 to the position shown in the drawing and bringing duct 52 into communication with duct 51. A complete cycle has thus been performed and the net or algebraic total volume of liquid discharged in this one cycle through the outlet 50 is the volume of the liquid collecting chamber 39.

To avoid lubricating the contact faces between the ro- Axial 6, tatable gas distribution valve" 19 and its housing there is a clearance of two thousandths of an inch between these faces and so to prevent leakage between

grooves

20, 21, 22 and 23 circumferential grooves (not shown) open to the atmosphere are provided between said

grooves

20 and 21, 21 and 22 and 22 and 23.

Should any one of the

diaphragms

41, 42 or 43 burst, the pump will cease to deliver liquid and liquid will not reach the gas distribution valve 19 through

pipes

44, 45 or 46.

What I claim is:

1. In a method of transporting a liquid explosive nitric ester from one location to another through joining conduit means, the improvements whereby the hazard of transmitting throughout the length of said conduit means, an explosion initiated at any point in said means is effectively eliminated, said improvements including the steps of (1) utilizing conduit means which comprise a set of tubes of pressure-resistant material that is chemically inert to said liquid explosive nitric ester, said tubes being arranged to form a multi-divided path for said ester with each of said tubes being at least three feet in length and having an internal diameter not greater than 0.1 inch, and (2) transporting said liquid explosive nitric ester through said tubes from one location to the other, by forcing said ester through said tubes under a forcing pressure which is less than 20 times the pressure on said ester prior to the application of said forcing pressure, and said tubes being of suflicient internal diameter to permit passage therethrough of said liquid explosive nitric ester under said forcing pressure.

2. A method as claimed in claim 1 wherein the pressure resisting material is based on a material selected from the group consisting of natural rubber, synthetic rubber and thermoplastic resin.

3. A method as claimed in claim 1 wherein a set of tubes consists of 10 to 400 tubes.

4. A method as claimed in claim 1 wherein the bore of each tube is not more than 0.09 inch.

5. A method as claimed in claim 1 wherein a set of small bore tubes is enclosed in conduit material filled with non-flammable fluid.

6. In combination, a source of liquid explosive nitric ester, means spaced from said source for receiving liquid explosive nitric ester from said source, and conduit means for transporting said ester from said source to said receiving means, said conduit means comprising a plurality of tubes of pressure resistant material that is chemically inert to said ester, said tubes being arranged to form a multidivided path for said ester, said tubes being of different lengths, each of said tubes being at least three feet in length and having an internal diameter not greater than 0.1 inch, and said tubes being of sufficient internal diameter to permit passage therethrough of said liquid explosive nitric ester under a forcing pressure which is less than twenty times the pressure on said ester prior to the application of said forcing pressure.

7. The combination of claim 6 including at least 10 tubes, said tubes being enclosed in a conduit permitting circulation of fluid therethrough.

8. Means for transporting liquid explosive nitric ester from one location to another, said means comprising a conduit joining one location with the other, said conduit including a set of tubes of pressure-resistant material that is chemically inert to said ester, said tubes being arranged to form a multi-divided path for said ester, said tubes being of different lengths, and each of said tubes being at least three feet in length and having an internal diameter not greater than 0.1 inch, and said tubes being of sufiicient internal diameter to permit passage therethrough of said liquid explosive nitric ester under a forcing pressure which is less than twenty times the pressure on said ester prior to the application of said forcing pressure.

9. In combination, a first building, a first protective Wall spaced from said first building, a second building, a second protective wall spaced from said second build ing, said protective walls being interposed between said buildings, a multiplicity of narrow bore tubes of not less than three feet in length provided through each of said walls, fluid conduit means intermediate said walls and connected to said tubes in each of said walls, a source of liquid explosive nitric ester in said first building, means for connecting said source to said tubes in said first wall, and means to connect said tubes in said second Wall to said second house.

References Cited in the file of this patent UNITED STATES PATENTS Jones May 9, 1933 Crowe Aug. 14, 1951 OTHER REFERENCES Fiat Final Report 720-28, January 1936, German Techniques for Handling Acetylene in Chemical Operations, by N. A. Copeland and Mt A. Youker, Joint Intel- 10 ligence Objectives Agency; published by Ofiice of Military Govt. for Germany (U.S.), call No. "RP. 248 A 3c6, pages 64 and 66 inclusive.