Device for the combustion of viscous fluids

Abstract: Equipment for combustion of viscous liquids such as tar from gas filters or the like, comprises a tank (6) with heating elements (4), a burner unit (5), and pipe (3) connecting the burner with the tank. The pipe protrudes into the tank, and the end of the pipe in the tank is connected to a dosage pump (2) of the displacement type.

Description: The present invention relates to equipment for combustion of viscous fluids as defined in the preamble of the attached claim 1. Carbon bodies being used in electrolysis cells for producing aluminium are prebaked (calcinated) in so-called ring section furnaces. Due to the strong environmental demands, the gases from such furnaces are cleaned, and one component which is separated in this connection is tar. The tar represents a problem with regard to how it should be deposited as it contains toxins (PAH), and has otherwise been difficult burn due to its consistency (viscosity at room temperature and contents of particles). Atempts have been done to buy equipment for combustion of the tar, but such equipment has proved not to be useful because of repeating running problems due to clogged valves and feeding pumps, and carburization of the combustion nozzle. DE-A-1501811 discloses equipment for combustion of liquids, comprising a tank, a burner unit and a pipe connecting the burner with a pump inside the tank. The inlet side of the pump is connected with a strainer which will easily become clogged by viscous liquids containing particles. Further, the equipment has no heating means or other means to keep the pipe, pump and burner open (unclogged) at all operating conditions. In view of the problems with the known equipment, it was decided to develop specially designed equipment for combustion of filter tar. An important object with the invention was to provide combustion equipment which would be reliable, i.e. where the problems with the clogging and carburization was eliminated and where the wearing of the equipment was reduced (long life). Further it was an object with the invention to provide cheap equipment which would be simple to maintain. The invention is characterized by the features as defined in the characterizing part of claim 1. With the solution according to the invention the pipe is prevented from being clogged, as the tank is heated and no valves or other narrow passes are provided in the pipe. Further, since the pipe close to the tank is provided with air evacuation means, the liquid is prevented from congealing in the pipe as it can be evacuated with air being blown through the pipe when the pump is stopped or is out of order. Claims 2 and 3 define preferred embodiments of the invention. The invention will now be further described by means of examples and with reference to the drawing which shows a principal sketch of the equipment for combustion of viscous liquids according to the invention. The equipment comprises a tank or container 6 with heating elements 4 controlled by a thermostat, a burner unit 5, and a pipe 3 for transferring liquid from the tank to the burner unit. The pipe 3 protrudes into the tank 6, and to the end of the pipe, slightly above the bottom of the tank, is connected a dosage pump 2. The part of the pipe protruding into the tank is preferably made of metal, whereas the pipe outside the tank may be flexible and made of a suitable rubber composition. The dosage pump 2 is driven via a shaft 9 by a motor 1 which is disposed outside the tank. The purpose of providing the motor outside the tank is to prevent it from being exposed to the high temperatures of the liquid in the tank, and besides to avoid problems related to sealing and mounting of electrical or hydraulical cables or pipes which otherwise would have to be led into the tank in connection with the pump drive. With the here described solution where the pump is provided in connection with the pipe inside the tank, there are no valves or other potential points on the pipe where clogging will occur. With regard to the pipe 3, this is in close vicinity of the tank, provided with air flushing means in the form of an air flushing pipe 8. By means of a valve 7 on the air flushing pipe 8, the liquid in the pipe 3 can be evacuated if the motor is stopped or the equipment for other reasons have come to a halt. As a further measurement the pipe 3, may also be provided with a heating element (not shown), to prevent clogging. To make it easier to mount and perform maintenance, the pipe 3 and the motor 1/dosage pump 2 is disposed in connection with an inspection cover 10 on top of the tank. Thus the pipe and the pump can be taken out of the tank by lifting off the cover 10, and the mounting and maintenance work may be carried out outside the tank. As previously mentioned, the tank is provided with heating elements 4 which are controlled by a thermostat. To prevent heat losses from the tank and to prevent the liquid from obtaining high viscosity or congealing in the pipe, both the pipe and tank is provided with heat insulation. The pump or rather the motor 1 is controlled via a frequency transformer by means of a computer. Hereby precise dosing is achieved and in turn precise temperature control for the combustion process. Even though it is initially explained that the equipment according to the invention is particularly developed to burn tar from gas filters, it is evident that the equipment can be used for burning other viscous liquids having high viscosity and particle content.

Claims: Equipment for combustion of viscous liquids such as tar from gas cleaning filters, comprising a tank (6), a burner unit (5) and pipe 3 connecting the burner with a pump disposed in the tank, characterized in that the tank further is provided with heating elements (4) to heat the liquid in the tank, and that the pipe in close vicinity of the tank is provided with air flushing means (8). Equipment according to claim 1, characterized in that the pipe (3) is provided with a heating element. Equipment according to claim 1 and 2, characterized in that the tank is provided with an inspection cover (10) and that the pump (2) and pipe (3) is arranged in connection with the cover (10).

Inventors: BOKLEP MAGNE, SOYSETH NILS ARVE, BOKLEP, MAGNE, SOYSETH, NILS ARVE
Applicants: NORSK HYDRO AS, NORSK HYDRO A.S.
Application year: 1991
Main classification: F23G7
IPC codes: F23G7