Abstract:
An apparatus for introducing a fluid into a container includes a supply leading into the interior of the container, closed by a bursting disk and connected to a supply line for the fluid. In order to increase the operational safety and to avoid clogging of the bursting disk, the supply is in the form of a telescopic tube which can be extended by the pressure of the fluid into the interior of the container and is mounted above the highest level in the container.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Apparatus for introducing a fluid into a container An apparatus for introducing a fluid into a container is used in particular for subsequent stabilization of substances which are usually stored in containers or storage tanks and which are distinguished by a strong tendency toward undesirable chemical reactions, for example premature polymerization, or other physical reactions, for example crystallization. 
     2. Discussion of the Background 
     It is known that certain substances or combinations of substances in solid or dissolved form are suitable for restabilizing the polymerizable substances which react at an undesirable time. These substances can be introduced into the stored material in a conventional manner and then mixed with the tank content by means of the pump which is usually used for tank farm facilities and which is provided for the purpose of filling and emptying tanks. The disadvantage here is that pumps themselves may be the starting point of a premature polymerization which causes blockage of the pump. Consequently, the mixing function can no longer be performed when required. A further disadvantage is the dependence on an external energy source for driving the pump, which, as a result of an emergency or by chance, may not be available, so that stabilization liquid cannot be introduced. 
     In order to be independent of external energy sources, a mixing process involving blowing in gases is therefore also used. A disadvantage of this is that additional baffles in or on the tank itself would have to be provided for this purpose. As a rule, such baffles must be firmly anchored to the tank in order to prevent them from being damaged or torn off during normal operation. In order to be effective, ie. to achieve good mixing, baffles for forcing in gases are usually located close to the bottom of the tank. When these baffles are not in use, the reactive substance can penetrate into the baffles and will gradually polymerize there owing to the slight exchange of material, so that, when required, the gas supply will be useless. A small air stream is therefore often passed through such lines in order to keep these lines free. However, such an air stream likewise needs to be monitored by means of apparatuses to prevent the liquid stored in the tank from rising and to keep the line open. Such designs have proven expensive for reliably performing the intended function. 
     EP-B 0 064 628 describes an apparatus for the emergency stoppage of polymerization reactions in a closed reaction container by the addition of inhibitor solution. The addition is effected in the lower region of the container via a connecting flange closed with a bursting disk. Mounted on this connecting flange is an angled riser line to an upper flange to which a pressurized gas line is connected. The riser line is filled with inhibitor solution which, when required, is forced into the container by the pressurized gas. 
     Although the operability of the apparatus should be independent of caked polymers and failure of the energy supplies, the regular monitoring usually required for safety apparatuses is more difficult in the case of these immersed baffles, and the bursting disk can be checked only when the container is empty. However, this means that the tank cannot be used during cleaning and checking. 
     SUMMARY OF THE INVENTION 
     According to the invention, the supply is in the form of a telescopic tube which can be extended by the pressure of the fluid into the interior of the container and is mounted above the highest level in the container. In the novel apparatus, where necessary the automatically activated telescopic tube dips into the material present in the container and carries liquid or gaseous substances into the material and simultaneously mixes the substances with the material. The fluid under pressure can be introduced into the container for stabilizing the substances present in the container and may be a mixture of a gas and a liquid. 
     Because the apparatus is installed above the highest permissible level in the container, it comes into contact with the material present in the container only when required, so that the operability is not impaired by the material present in the container. 
     Moreover, the apparatus can be mounted on the container or removed at any time, regardless of whether the container is in operation or not. This permits a regular function test to be carried out in a simple manner. Owing to the design of the apparatus, it can, without change of dimensions, be installed in containers with very different contents without influencing the efficiency or the operability. 
     Preferred embodiments are described below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 shows a schematic section through an apparatus installed in a container wall and having a retracted telescopic tube, 
     FIG. 2 shows the telescopic tube extended a distance, 
     FIG. 3 shows a detail of a locking apparatus for the telescopic tube and 
     FIG. 4 shows the apparatus with the first inner tube of the telescopic tube completely extended from the housing tube. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a schematic section through a novel apparatus installed in a container wall  1 . The container wall  1  has an orifice  2  with a vertical connecting flange  3 . A telescopic tube  4  of the apparatus for introducing fluid into the interior  5  of the container bounded by the container wall I projects through the orifice  2 . 
     The telescopic tube  4  consists of an outer housing tube  10  and three inner tubes  11 - 13 , which are sealed from one another by means of seals  14 . The inner tubes  11 - 13  have, at their ends, retaining rings  15 ,  16  which limit the axial movement of the inner tubes  11 - 13  when being pulled out. 
     The central inner tube  13  is provided, at its end  13 . 1  located in the interior  5 , with a holder  17  for a bursting disk  18 . In addition, the holder  17  is continued outward to such an extent that the other inner tubes  11 ,  12  can rest thereon. At the other end  13 . 2 , the inner tube  13  has an inner collar  19  and an extension  20  which extends above the retaining ring  16  and whose function will be explained later. 
     The housing tube  10  is provided with a support flange  21  for fastening to the flange  3  of the container wall  1 , it being possible to effect fastening directly or with the use of an intermediate flange  22 . Furthermore, the housing tube  10  has a second flange  23  for fastening a locking apparatus  24 . A supply line (not shown) for the fluid to be introduced into the interior  5  is connected to this locking apparatus via a pipeline flange  25 . 
     The locking apparatus  24  comprises a housing  26  which encloses a piston chamber  27  connected directly to the pipeline flange  25  with regard to flow, with formation of an interior  28 . Arranged in the piston chamber  27  is a piston  29  which, in the initial state, is present inside the piston chamber  27  in a position facing the pipeline flange  25 . 
     In the region not covered by the piston  29 , the piston chamber  27  has an orifice  31  providing the connection, permitting flow, with the interior  28 . This orifice  31 , which may be in the form of a slot, is not opened until the piston  29  reaches a lower position. 
     The interior  28  is connected via a further orifice  32  to a pressure chamber  33  which is bounded by the locking apparatus  24  and the inner tubes  11 - 13  located inside the housing tube  10  and from which the movement of the inner tubes  11 - 13  begins on application of fluid under pressure. The connection permitting flow is indicated by the arrows. 
     Means for locking and for releasing the inner tubes  11 - 13  are furthermore mounted in the pressure chamber  33 , said means being described in more detail in FIG.  2 . 
     In FIG. 2, the telescopic tube  4  is shown extended a distance. For this purpose, the locking apparatus  24  was actuated so that the piston  29  is in a lower position inside the piston chamber  27 . As a result of the axial displacement of the piston  29 , catches  34  present in the pressure chamber  33  are released from lock openings  35  in the upper end  13 . 2  of the central inner tube  13 . This release movement is indicated by the arrows  36 . 
     Furthermore, during its axial displacement, the piston  29  has come to rest against the inner collar  19  and has assisted the extension movement of the inner tubes  11 - 13 . 
     To permit this release, the catches  34  are mounted on spring tongues  37  and have a surface  38  which faces the piston  29 , is beveled in the direction of movement and is shown on a larger scale in FIG.  3 . In the locked position, the catches  34  extend through the lock openings  35  of the upper end  13 . 2  of the inner tube  13  and penetrate a distance into a recess  39  in the piston  29 . The recess  39  has a shape corresponding to the catches, so that the catch slides on its beveled surface  38  out of the recess  39  during the axial displacement of the piston. To reduce the friction, the catch  34  may consist of PTFE (polytetrafluoroethylene). In the embodiment, the lock openings  35  are slot-like openings cut into the upper section of the central inner tube  13 . 
     To prevent the catches  34  from unintentionally sliding out under the gravitational effect of the piston  29 , the catch may be arranged on an appropriately stiff spring tongue  37  or a spring-loaded lever. The initial tension of the spring tongue  27  is chosen so that the force due to the weight of the piston  29  and acting on the beveled surface  38  is at least compensated. 
     Since the catch must also bear the total weight of the inner tubes  11 - 13 , it has, in addition to the sliding region formed by the beveled surface  38 , a retaining region having a straight surface  40  which interacts with a corresponding surface of the lock openings  35 . As a result of the catch  34  sliding out of the recess  39  in the piston  29 , the straight surface  40  is disengaged and the inner tube  13  can likewise slide past under the catch  34 , along the beveled surface  38 . The movement of the inner tubes  11 - 13  is initially supported by the piston  29 , during its axial displacement, resting against the inner collar  19 , and the extension movement is initiated. 
     FIG. 4 shows the apparatus with the outermost inner tube  11  completely extended from the housing tube  10 . The volume of the pressure chamber  33  has continuously increased as a result of being subjected to fluid under high pressure. 
     The locking mechanism in FIG. 4 has completely released the central inner tube  13 , whose end  13 . 2  with the opening  35  is now at the lower end of the housing tube  10 . It is clearly evident that, as a result of the displacement of the piston  29  inside the piston chamber  27  to a lower position, the catches  34  have come out of the recess  39  in the piston  29 . The beveled surface  38  of the catch  34  and the corresponding surface of the recess  39  facilitate this sliding out against the spring force of the spring tongue  37 . 
     The novel apparatus is fed with the fluid to be introduced via a supply line which is connected to the pipeline flange  25  and is not shown. A certain amount of this fluid is available under a certain pressure in a storage vessel and is not connected to the supply line until a danger arises. As a rule, the fluid to be introduced is a liquid which is present in a pressure-resistant container. This pressure-resistant container may be a conventional fire extinguisher container having a firmly connected propellant bottle. By opening the propellant bottle, the liquid is first expelled from the pressure-resistant container and introduced into the tank content through the telescopic tube  4 . The excess gas subsequently flowing produces thorough mixing of the tank liquid with the injected fluid as a result of the vertical flows generated by ascending gas bubbles. It is thus sufficient if the pressure-resistant container is connected to the supply pipe by means of a fast-acting coupling immediately before the gas bottle is opened. 
     If the storage vessel is actuated, the pressure prevailing in the storage vessel is transmitted to the piston  29  in the piston chamber  27 . As a result of the force acting on the piston  29 , the piston  29  moves in the piston chamber  27 , possibly against the spring force of a pressure spring. 
     First, the catch  34  is forced out of the recess  39  and thus the lock is released; on the other hand, the piston  29  comes to rest on the retaining ring  19  and pushes the central inner tube  13  below the catches  34 , which come out of the lock openings  35 . 
     As soon as the piston  29  has reached the lower retaining point in the piston chamber  27 , gas and/or liquid flows via the horizontal orifices  31  into the lateral interior  28  and via further orifices  32  into a pressure chamber  33  above the movable inner tubes  11 - 13 . The force of the applied pressure is now transmitted to the upper end surface of the inner tubes  11 - 13 , the seals  14  between the inner tubes  11 - 13  and the housing tube  10  and the bursting disk  18  set to a certain gas pressure and located at the lower end  13 . 1  of the central inner tube  13  preventing an escape of pressure into the container. 
     The attempt by the pressurized fluid present in the pressure chamber  33  to expand gradually moves the inner tubes  11 - 13  downward. Owing to the larger circumference and hence the larger contact surface of all outer inner tubes  11 ,  12 , these are initially moved downward. Since the outer and inner tubes  11 ,  12  rest on the holder  17 , the central inner tube  13 , too, is moved downward together with these. If the outermost inner tube  11  with its retaining ring  16  rests against the retaining ring  15  of the housing tube  10 , the volume of the pressure chamber  33  increases as a result of the downward movement of the next inner tubes  12 ,  13  and forces these downward. The increase in the volume of the pressure chamber  33  ceases when all inner tubes  11 - 13  have reached the lower retaining point or the central inner tube  13  rests against the bottom of the container. If necessary, it is possible to provide a spacer which avoids coverage of the lower end by the container bottom and is not shown. 
     Since further expansion of the fluid-filled pressure chamber  33  can no longer occur, a pressure gradually builds up. When the maximum pressure required for destroying the bursting disk  18  has been reached, the fluid present in the pressure chamber  33  expands through the telescopic tubes  4  into the container interior  5 . 
     If the fluid continuing to flow is a mixture of liquid and gas, the gas continuing to flow ensures that the liquid forced in is mixed with the container content. 
     The apparatus is fastened to the tank flange  3  by means of the support flange  21 . For mounting at the desired distance above the maximum liquid level inside the container, intermediate flanges  22  of different heights may be used. Since the design having a square cross-section is preferred for large containers of increasing volume, the preferred range of use of the invention relates to containers having a volume of from 20 to 1000 m 3 , corresponding to a telescope extension of from 3 to 11 meters. In conjunction with suitable containers for receiving the stabilizer liquid and suitable fast-action couplings, the apparatus permits economical, reliable and low-maintenance safety means, in particular for the storage of reactive substances. 
     The apparatus is particularly suitable for carrying out a process for immediately terminating free radical polymerizations by adding a phenothiazine-containing inhibitor solution to the system undergoing free radical polymerization, the solvent of the inhibitor solution comprising at least 50%, based on the weight of said solvent, of an N-alkylpyrrolidone. The N-alkylpyrrolidone may be N-methylpyrrolidone and/or N-ethylpyrrolidone. 
     Furthermore, it is advantageous if the phenothiazine content of the inhibitor solution is at least 10, preferably about 35-45, % by weight, based on the weight of the inhibitor solution. The apparatus can be advantageously used in particular when the system undergoing free radical polymerization comprises (meth)acrylic monomers undergoing free radical mass polymerization, it being possible for the (meth)acrylic monomer to be a (meth)acrylic acid and in particular a (meth)acrylate. 
     The apparatus is particularly suitable for immediately terminating free radical polymerizations, containing a phenothiazine-containing inhibitor solution, when the solvent of the inhibitor solution comprises at least 50%, based on the weight of said solvent, of an N-alkylpyrrolidone. Furthermore, the apparatus is suitable for an inhibitor solution which contains phenothiazine and an N-alkylpyrrolidone, in particular N-methylpyrrolidone.