EP0689476A1

EP0689476A1 - Dosing system

Info

Publication number: EP0689476A1
Application number: EP94910420A
Authority: EP
Inventors: Walter THÜNKER; Gabriele Lohmann; Arnim Marschewski; Tage Ib Nielsen; Christian LÜTZEN
Original assignee: Chemische Betriebe Pluto GmbH; Dampskibsselskabet AF 1912 AS; Dampskibsselskabet Svendborg AS
Current assignee: Innospec Deutschland GmbH; Dampskibsselskabet AF 1912 AS; Dampskibsselskabet Svendborg AS
Priority date: 1993-03-20
Filing date: 1994-03-15
Publication date: 1996-01-03
Also published as: WO1994021364A2; PL310676A1; WO1994021364A3; IS4141A; AU6284394A; DE4309065C2; DE4309065A1; ZA941940B

Abstract

System for feeding a solid into a liquid that is able to dissolve this solid, said system being provided with a container (1) for the liquid and, inside said container, with a receptacle (4) for the solid.

Description

Dosing system

The invention relates to a metering system for introducing a solid into a liquid which is able to dissolve this solid. In particular, the invention relates to a metering system for the additization of heavy marine diesel oil with ferrocene and / or ferrocene derivatives.

From DE-OS 1 927 765 a metering device for dissolving a solid in a side stream of a liquid is known. However, in accordance with the task, this invention is directed to a metering device which is suitable for the water treatment of water flowing in the swimming pool with fixed amounts of a chlorine-containing substance which is initially in solid form (granules). An essential component of this device is a container with a relatively large amount of solid, which is covered with liquid. It is assumed that the concentration of the dissolved solid in this liquid is constant. This is then drawn off accordingly and metered into the main stream while fresh liquid is topped up in the container. In order that the outgoing solution always has the same concentration, it must be assumed with this system that the residence time of the freshly supplied liquid above the solid is always the same for setting the solution equilibrium, that the container is still and firm, ie none Is exposed to vibrations, which cause an additional relative movement of the liquid and thus influence the rate of solution, and the temperature is constant, since this also influences the solubility behavior.

Such a dosing system would be unsuitable for use on board ocean-going ships, since depending on the engine performance, different flow rates can be expected, different degrees of sea conditions lead to differently sized relative movements of the liquid in the container, and different temperatures (depending on latitude and weather conditions) make the solution soluble ¬ influence behavior, so that even halfway accurate dosing would not be possible.

The object of the invention is therefore to provide a metering system which does not have the disadvantages described and which can be used for the application areas mentioned. The system should be relatively simple and robust to work under to be able to work without problems and maintenance under the conditions mentioned. In addition to simple handling, there should also be the possibility of metering the solid or of regulating the liquid / solid ratio to concentrate the solution in the range up to the max. Adjust solubility as desired.

The task was solved by a dosing system for introducing solids into liquids which are able to dissolve these solids, which has the following features:

a container (1) for holding liquid, an inlet (3) which can be regulated via a valve (2), a container (4) for the solid which is located inside the container (1) and at least partially penetrated by the liquid therein can be a metering pump (7) downstream of an outlet (6) and possibly further units or control devices for temperature and filling

Status control.

With the dosing system according to the invention, constant additives can also be used under extreme conditions e.g. achieve on board a large ship suitable for sea use in heavy seas.

A preferred embodiment additionally includes a device (8) which constantly mixes the liquid in the container (1) and flows through the container (4) which contains the additive in solid form. Various embodiments are suitable for this device (8). For example, the liquid in the container (1) is constantly circulated by a pump. However, a stirrer is preferably used. The design of the stirrer (eg propeller stirrer), its dimensioning, speed and its drive are freely selectable and depend on the shape and size of the container (1), the viscosity of the liquid, etc. However, the person skilled in the art knows which stirrer he is using under which framework conditions can best be used.

Furthermore, it is preferred that the metering system has an addition device (9) for filling the container (4) with solid. About this addition device, which in the simplest case is a funnel, the solid is added. This, as a rule, metered addition can take place in the form of ready-made units, by measuring beaker or by manual weighing. An automatic feed of the solid can also be installed. In principle, all devices that are intended for measuring and dosing solids and that can be found in corresponding reference works, such as belt scales, are suitable for this.

In addition, the metering system can have a device for tempering the liquid in the container (1). These can be cooling or heating coils, for example, which are located in the container (1) and are constantly flushed with liquid. However, a double-walled container (1) is also suitable, through which cooling or heating media (e.g. steam) are passed between the two walls. An electric heater is also possible. In addition, a regulation can be provided which controls the cooling or heating in such a way that the container contents are kept constant at a certain temperature.

The container (4) can be made of different materials and different shapes. It is important that the material should be inert to the feedstocks and that there is also the possibility that the liquid can flow through the container (4). The container (4) can e.g. Have pores, meshes or holes through which the liquid can flow. It is preferred to use a filter cartridge or a filter basket. The choice of the type of container depends on the type and shape of the solid to be detached and on the properties of the liquid. The experienced specialist will be able to make the right choice here without any problems. For example, a filter basket with a metal mesh fabric with a mesh size of 0.5 to 5 mm has proven to be very suitable for the additization of heavy oil with powdered baked ferrocene. In principle, the solids can be supplied in various comminuted forms. All intermediate stages between coarse to finely ground solid are possible. This also includes other forms such as granules, pellets or flakes.

In a preferred embodiment, the metering system contains a device (5) by means of which the liquid level within the container (1) can be regulated. This device is designed so that at a certain low level (Iow) of the liquid in the container (1) via the inlet (3) controlled by a valve (2) as much liquid is again introduced into the container (1) until a certain maximum level (high) of the liquid level is reached. Various embodiments of the device (5) can be used for this regulation, for example optical systems, liquid level indicators, flow meters, etc. Such measuring and control elements are known to the person skilled in the art. However, float switches are preferably used in such a way that one float switch is used for the lower (Iow) and one for the upper (high) liquid level. Regardless of the type of device (5), it is important that defined amounts of fresh liquid are always supplied.

A preferred embodiment of the invention uses a frequency-controlled pump as the metering pump (7), which can be regulated as a function of the load or the speed of the ship's propulsion unit. If the solution transported via the pump (7) is fed to a main flow of liquid, the metering pump (7) is preferably coupled to the pump for conveying the main flow from the storage tank in order to ensure a uniform additive. Preferably, the liquid which is fed to the container (1) via the line (3) is branched off as a secondary flow from a main flow of the liquid and then the solution is fed back to the main flow via the line (6).

However, it can also be preferred to remove the liquid which is supplied to the container (1) from a separate storage container or fuel flow. This applies in particular if the liquid for dissolving the solid is to have a different composition than that of the main stream.

The metering unit according to the invention is suitable for metering solid additives to liquid fuels, in particular for adding heavy heating oil with ferrocene, preferably on board large ships suitable for use on the high seas. Heavy diesel or heating oils are classified according to ISO 8217 and have a density of approximately 0.9 to 1.0 kg / dm ^.

The dimensioning of the device essentially depends on the throughput quantities. The person skilled in the art will make the suitable choice here without difficulty. For example, with a main flow of several tons per hour and an intended additive concentration of up to 100 ppm, there is a container (1) with a capacity of 100 to 200 l. The container (4) should then be able to hold a few kg of solid.

Description of Figures 1 and 2

Figure 1 shows a container (1) for receiving liquid (not shown here), which is introduced via an inlet (3) which is controlled by a valve (2). The container (4) contains the solid (not shown here) which can be filled in via the device (9), in the simplest case a funnel. Furthermore, a stirrer (8) can be seen. The inflow of fresh liquid is regulated by two float switches (5). If the liquid level reaches the lower float switch, i.e. the Iow position, the valve (2) is opened after the solids have been added. This can be done manually or automatically. When the liquid level reaches the upper float switch, i.e. the high position, the valve (2) closes. The solution can be passed to the consumer or combined with the main flow via the outlet (6) and a metering pump (7) controlled by means of a control device.

In the sense of an exemplary embodiment, FIG. 2 shows the integration of the metering system in a fuel system. The main flow of the fuel is fed via a line (10), if necessary via a cleaning system such as a separator (11) is introduced into a service tank (12) which is smaller in size than the storage tank (not shown here). A partial flow is fed to the metering system (shown here only schematically) via the inlet (3). The additive solution is then reintroduced into the main stream (10) via the metering pump (7) and the line (6). The fuel is then fed from the service tank (12) to the consumer via a pump (13). The fuel pump for conveying the main flow from the storage tank and the metering pump (7) can be coupled (not shown here).

The present invention is further illustrated by Examples 1 and 2 below.

example 1

A mixing tank model was set up in the laboratory. This model was equipped with an adjustable stirrer motor and an impeller stirrer with 1,350 revolutions. hours / min. A filter basket with a mesh size of 500 μm was used for the ferrocene entry. In addition, the model was equipped with a heating coil so that thermostatting was possible. The dependence of the solution speed on the temperature during the production of a 3% by weight ferrocene solution was checked.

Temperature [° C] 22 30 40 50

Time [min] (DK) 55 30 15 7

Time [min] (DMDO) 65 35 18 8 Time [min] (MDO) 75 40 20 12

DK: Diesel fuel (commercially available goods according to DIN 51601) DMDO: dest. marine diesel oil (standard product according to ISO 8217, DM type) MDO: marine diesel oil (standard product according to ISO 8217, RM type)

Example 2

The metering device according to the invention for adding ferrocene to the fuel was installed on board a container ship (60,000 GRT). For the additive, an approximately 3% by weight ferrocene solution was prepared and metered into the fuel line between the separators and the service tank (FIG. 2).

Various additive rates were set during a test trip on the high seas. With the device according to the invention (FIG. 1) it was possible to achieve a solution time of ferrocene in MDO <1h. With a solids use of 4.5 kg, this was completely dissolved after 60 min at a concentration of the solution of 3.5% by weight. After 30 minutes, the concentration was only 2.4% by weight. An approx. 3% by weight solution was added to the flow in a 40 t service tank (12). The tank was filled with about 30 t and the flow rate was about 6.5 t / h.

In order to be able to reach the desired final concentration (here 10, 20, 50 and 100 ppm) more quickly when changing the additive rate, the following function was added: - (time * flow / vol) Konzf _U e | = Conc _max ^* [1 - e]

Konzf _ue | = intended ferrocene concentration in the service tank

Conc _max = at the dosing pump through the max. Pump capacity adjustable max. Konz. (Konz _max > Konzf _ue |) flow = flow through the service tank vol = content of the service tank time = time

The ferrocene concentrations were analyzed by X-ray fluorescence after the trip. The results are shown in Tab. 1.

Tab. 1 Ferrocene concentrations

Test No. intended concentrations measured concentrations

1/2 0 ppm 0 ppm

3 10 ppm 16 ppm 4 20 ppm 23 ppm

5 50 ppm 53 ppm

6 100 ppm 107 ppm

Claims

1. Dosing system for introducing a solid into a liquid which is able to dissolve this solid, which has the following features:

a container (1) for holding liquid, an inlet (3) which can be regulated via a valve (2), a container (4) for the solid which is located within the container (1) and which is in the container (1 ) located

Liquid can be at least partially penetrated, a metering pump (7) connected downstream of an outlet (6) and optionally further units or control devices for temperature and fill level control.

2. Dosing system according to claim 1, characterized in that a Vor¬ device (8) is present, which mixes the liquid in the container (1) and can flow through the container (4).

3. Dosing system according to claim 2, characterized in that the Vorrich¬ device (8) is a stirrer.

4. Dosing system according to at least one of the preceding claims, da¬ characterized in that an addition device (9) for filling the container (4) with solid is present.

5. Dosing system according to at least one of the preceding claims, characterized in that a device for tempering the liquid in the container (1) is present.

6. Dosing system according to at least one of the preceding claims, characterized in that the container (4) is a filter cartridge or a filter basket.

7. Dosing system according to at least one of the preceding claims, characterized in that a device (5) for determining the flow liquid level in the container (1), via which the liquid supply is to be regulated by means of a valve (2) and which consists of at least two float switches.

8. Dosing system according to at least one of the preceding claims, da¬ characterized in that the metering pump (7) is frequency controlled.

9. Dosing system according to one of the preceding claims, characterized gekenn¬ characterized in that the liquid of the inlet (3) is branched off from a main stream and the solution (6) via the metering pump (7) is returned to the main stream.

10. Dosing system for the additization of liquid fuels, in particular heavy marine diesel oil with ferrocene and / or ferrocene derivatives.