Patent Application
20250002831
The present invention relates to equipment and methods for removal of sand or other materials from biogas reactors and other equipment. More specifically, the invention relates to removal of settled sand that may have become more or less solidified, or other unwanted material that may accumulate in equipment during operation, while said equipment can be in operation at elevated pressure and temperature.
Sand settles in numerous types of equipment. The sand must typically be removed for not reducing the capacity of the equipment and not reducing the reliability and service life of equipment further downstream in a process.
A very relevant example of equipment is biogas reactors, used to produce biogas from organic waste or manure. The organic waste or manure may contain sand and other material not active in the biogas production process.
A biogas reactor is typical of volume 1000 m3 to 6000 m3. In practice, after some period of operation, a layer of more or less solidified sand, in average 1 m to 3 m thick, typically fill the bottom part of the reactor. This means that about 10 to 20% or often more of the reactor volume is filled with sand. The capacity of the reactor is reduced accordingly. In addition, the reactor must be shut down when sand shall be removed. Typically, such shut down results in about one to two months out of operation until full biogas reactor operation is resumed. Removal of sand and resulting shut down is required at an interval typically of about every second or third year. The sand sedimented out in the tank over time may transform from soft sand to semi solid sand to a more solid-like material. Longer periods between shut down for sand removal may therefore increase the problem.
Apparently, no equipment exists allowing the sedimented sand, more or less like a solid or semi solid material, to be taken out from a biogas reactor without stopping operation of the reactor. A reason may be the technical and practical challenges faced. Some biogas reactors are operated at elevated pressure and temperature, from a few mbar and at least up to pressure of 25 bar and temperature up to 150°. Elevated temperatures, pressures and abrupt changes thereof are essential operation steps of some biogas or other production processes.
Searching has revealed only one patent publication of some relevance for the underlying problem of the present invention, namely U.S. Pat. No. 7,240,681 B2, relating to a mobile apparatus for removing formation sand from an oil storage tank. According to U.S. Pat. No. 7,240,681 B2, two separate pipes are flanged to the tank wall. A first pipe is inside the tank, with one end coupled to a slurry formation tool and an opposite end coupled to a first flange in the tank wall. A second pipe is outside the tank and is coupled to an outlet in the tank wall for withdrawing the slurry formed by the slurry formation tool from the tank, wherein the outlet is in the form of a second flange through the tank wall. The two flanges on the tank wall can in one embodiment be a combined pipe in pipe flange. Searching outside patent literature has not revealed any prior art that appears to be of more relevance with respect to the present invention than U.S. Pat. No. 7,240,681 B2.
The objective of the invention is to provide a tool or equipment improving the removal of sand and other unwanted material from biogas reactors and other tanks and equipment subject to more or less the same problems as described above with respect to biogas reactors.
The invention meets the objective by providing a tool for sand removal from biogas reactors and other containments, feasible for sand removal while the biogas reactor or other containment is in operation at elevated pressure and temperature.
The tool is distinctive in that it comprises:
For many preferable embodiments, the tool further comprises an eductor, arranged in the second flow path with eductor suction inlet fluidly coupled to the outlet opening, or the eductor suction inlet is the outlet opening. Some preferable embodiments comprise several outlet openings. For an eductor, the motive fluid is a liquid and the produced vacuum or underpressure is used to draw in other liquid/fluid and sand and mix it with the motive liquid. However, the term ejector is often used synonymously, even though an ejector uses a gas as the motive fluid creating vacuum or underpressure.
The term high pressure liquid source means a source, such as the pressure side of a pump or a pressurized storage tank, enabling high pressure liquid injection through the nozzles, that is liquid injection at higher pressure than the pressure inside the reactor or containment from where sand shall be removed. This includes for example the high pressure feed flow 14 on
For frequent sand removal, without very hard sediments, the main feed flow will typically be sufficient, with liquid overpressure typically up to about 2-10 bar above the reactor/containment pressure, and appropriate tools are designed accordingly, that is with only main feed flow or similar as preferable embodiments. For very hard sediments, a high pressure feed flow in addition or instead is required, with overpressure that can extend up to several hundred bar, and appropriate tools are designed accordingly, that is with one or several high pressure liquid conduits included in preferable embodiments.
Preferably, the tool comprises a single coupling part coupling the two flow conduits to a single tubing or pipe with two corresponding flow conduits, preferably by mating a pipe in pipe coupling part on the tool to a corresponding pipe in pipe coupling part in the end of a single pipe with two flow conduits.
Most preferably, the tool comprises only one coupling to a single pipe, such as a flexible pipe or flexible tube, which single pipe or tube includes at least two flow conduits. Such embodiments are preferable in general for operating in pressurized tanks, reactors, or equipment under elevated pressure and/or temperature since a single leak proof feedthrough can be arranged in an opening in a wall thereof.
Alternatively, the tool comprises several coupling parts, up to one coupling part for each conduit and/or function, such as two, three, four or more coupling parts.
Preferably, the tool comprises nozzles and outlet opening or eductor suction inlet in one and the same end of the tool and coupling part or parts in the opposite end of the tool. The outlet opening and/or the suction inlet to the eductor preferably is arranged coaxial to a longitudinal tool axis.
The tool preferably comprises nozzles directed in two or three directions, such as along or with direction components in x, y and z orthogonal directions, allowing positioning the tool in a tank within volumes of interest for removal of sand, wherein said positioning includes using the reaction forces created by operating the nozzles. In some preferable embodiments of the tool the nozzles 5 used for positioning may be fed by separate high pressure tubes or hoses.
Preferably, the tool in operation brakes up and fluidize sand settled in a tank or other equipment, disperses the sand in liquid, thinning the sand in the eductor and sucks out sand slurry.
One embodiment of the present invention is a combination of a tool of the invention coupled to a flexible tube or pipe brought sealingly through a tank wall opening or equipment wall opening, wherein the opening and related equipment comprises an injector head, packing box, lubricator, stuffing box, and/or slickline 15 seal and/or similar equipment through which the flexible tubing or a rigid pipe section is brought. Alternatively, the combination comprises two, three or more pipes or tubes brought sealingly through a tank wall. With the combination of the invention, while the tank or equipment is being emptied for sand, the tank or equipment, such as a biogas reactor, can be operated for biogas production as 20 normal, at normal operating parameters.
In the context of the tool, combination and use of the present invention, the term sand can mean not only sand but any process inactive material reducing the active volume in the tank or equipment, such as sand, stones, pebbles, egg 25 scales, shells, hard scales, concrete, ceramics, polymers, glass, metal, and also viscous foam or fluid that can be formed as unwanted by-products in tanks or equipment.
Preferable embodiments of the tool and/or combination of the invention May include one or more of the features as follows, in any combination:
The tool 1 comprises a number of nozzles 3, in operation directed at volumes 4 with solid, semi solid or soft sand, in the lower part of a biogas reactor 2. The effect of operating the nozzles by high-pressure liquid injection is to create a flowable sand slurry. The sand slurry is brought out through the second flow path, via the eductor of the tool, wherein the eductor is arranged with at least one suction opening facing the flowable slurry created by the nozzles. The tool comprises two flow paths, integrated in the tool, each flow path being fluidly coupled to one or both of the nozzles and the eductor, wherein a first flow path is for high pressure fluid to be injected through the nozzles and/or to create suction effect in the eductor, and wherein a second flow path is for returning slurry collected by operating the eductor. The detailed design of the tool embodiment illustrated, is easier understood by referring to
| Number | Date | Country | Kind |
|---|---|---|---|
| 20211383 | Nov 2021 | NO | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NO2022/050262 | 11/15/2022 | WO |
