DE4100255A1 - Maintaining constant solid to liq. ratio in moving sludge - by computer-controlled injection of corrective mixt. of same materials - Google Patents

Abstract

In maintaining a desired final solid/liq. ratio in a stream of material which is not free-flowing, is pasty and/or sticky and difficult to pump, deficiencies in a main stream are corrected by adding a second stream. Both vol. and mass of the main stream, esp. of clarified sewage sludge are measured. The second stream contains a higher proportion of solids, either known in advance or readily measured, with the actual nature of the solids, the same for both streams. The final ratio in the emerging combined flow is applied to a controller acting on the second stream supply to produce the desired value. The second stream derives from a stored supply, or is recovered from a correctly balanced combined flow. ADVANTAGE - Avoids need for difficult continuous measurements of solids and moisture in the initial flow.

Description

The invention relates to a method for producing and Maintaining a pre-selectable qualified festival substance / liquid ratio in a non-flowable, difficult to pump, paste and / or sticky mass flow or the like. With permanently variable proportions of Liquid component to solid component, preferably Sewage sludge.

It is sometimes he, especially in processing technology required such mass flows in an aggregate state to be transferred to that of a pourable solid nelt. A centrifugation or other mechanical dewatering steps, the mass flows of the type mentioned only withdraw a certain amount of liquid, ge are generally not sufficient, especially since they are undesirable Side effects such as densifications, conglomerations, Cake and lump formation or the like can occur. A Preparation for pourable consistency is used, for example to be able to silage the materials or keep them there enable the substances in conventional conveyors inexpensive to transport or use for further to make processing equipment eligible.  

The invention has for its object a method of to create the type mentioned, by means of which an gangsmassenstrom of the type described above in one outgoing mass flow with selectable qualified Solid-liquid ratio can be converted, so that with the outgoing mass flow the production of a constant, static or dynamic slope angle possible Lich, which is a constant bulk or flow behavior guaranteed.

For the treatment of coal sludge it is from DE-OS 33 03 977 known, an input coal sludge with variable Solid / liquid proportions to reduce the relati to supply solid liquid in such quantities, that the solid / liquid proportions of the starting product correspond to a preselected ratio. This method but is difficult for the treatment of a non-flowable pumpable, pasteous and / or sticky mass flow, such as for example sewage sludge, not applicable because it such mass flow is practically impossible, reliable and undistorted immediate measurements of the respective solid and liquid fractions as relative values or absolute values to obtain. In the known method, the Solid addition based on measurements of the solid Substance / liquid portion of the input product. Because derar measurements at mass flows of the ones in question Art can not be made is the known Process for making a preselectable qualified Solid / liquid ratio for mass flows of not suitable here.

The invention has for its object a method of to create the type mentioned without a continuous solid or moisture measurement in the Input mass flow is required.  

To solve this problem, the invention provides that the mass flow is permanently fixed in volume and mass is set, and that this input mass flow for formation one to the desired solid / liquid ratio pointing outgoing mass flow a second mass flow is metered with a high solids content, the Solid / liquid ratio of the second mass flow is known or easily measurable and the solid together The second mass flow rate is that of the input mass flow corresponds, and that the solid / liquid ratio of the outgoing mass flow continuously is measured and that this measured value together with the Quantity value of the input mass flow and the known weights of the solid and the liquid portion of the one aisle mass flow for the mathematical determination of the supply amount of the second mass flow is used, and that the amount of the second mass flow metered in Computer output signal is determined.

In an advantageous embodiment of the invention can continue be provided that the second mass flow from an external NEN stock and / or taken from the outgoing mass flow and is fed.

In the method according to the invention, any moisture content can a second to be added immediately in the input mass flow Mass flow can be assigned to a desired Preselected solid / liquid ratio in the outgoing To achieve mass flow. This result is achieved without that a continuous solid or moisture measurement in the input mass flow is carried out. The infinitesimal Computing speed of the computer represents when it is carried out of the process continuously the desired quantitative relations here.

It is also advantageous that the continuous, machi Fast, arithmetical evaluation of the measurement results and their  Implementation on control devices any number of process-relevant Can process product parameters as constants. The desired proportions of solid / liquid in End product can be set arbitrarily. Correction with regard to the type of computational evaluation of the Measurement results and their implementation on control devices are anytime possible.

An exemplary embodiment is described below.

A non-flowable, difficult to pump pasteuser and / or sticky sewage sludge is mixed with irregular proportions Solid (X) and moisture (Y) introduced. It is practical impossible, reliable and in such a mass flow undistorted immediate measurements of the respective solid and Perform liquid proportions. Such measurements are only possible if a constant flow behavior in in this case the pourability is established. According to the Invention is a measurement of the variable proportions of solid (X) and humidity (Y) in the input mass flow Q org by a Computing operation replaced in a microprocessor. Here are known: The weight of the solid compo designated c1 and the c2 weight of the moisture compo nente. These values are used as a constant in the computer program entered.

The mass flow Q org is kept constant with respect to its mass and volume at a preselectable value. In terms of volume, this can be done, for example, by the regulated output of a slurry pump and in terms of volume, for example, by means of continuous weighing via a downstream belt scale. The input mass flow Q org is calculated from the equation
Q org = X × c1 + Y × c2 = const. Volume with known Oe important.

The variables X and Y remain as variables (e.g. in%) in mass flow Q org.

The outgoing mass flow is subsequently entered with Q Tr or Q tot out designated. Q Tr on is the outgoing mass flow after admixing a second mass flow, which is egg nem dryer is supplied. Q tot out is the outgoing Mass flow after the processing process, i.e. the dry nung. The mass flows Q Tr on and Q total off are bulk hig, and it is thus a continuous measurement of the Moisture content, e.g. B. by isotope measurement possible.

The supply of a second high mass flow Solid content in the input mass flow can be quantitative or regulated by volume. A quantitative regulation can for example by continuous weighing with Keeping the flow rate constant via a controllable Conveyor body in front of a scale. A volume Regulation can be carried out by a calibrated funding body (e.g. Dosing screw). The amount of the second fed Mass flow is determined by a computer Controlled variable "r" regulated. The second mass flow corresponds to its composition (solid content a = const., Moisture content b = const. = measured) exactly the outgoing Mass flow Q tot out.

The mass flow Q ges is z. B. in t / h over a continuous weighing (belt scale) determined. The outgoing Mass flow Q Tr is z. B. over a continuous Weighing (belt scale) determined.

The moisture content b in the outgoing mass flow Q tot is made e.g. B. continuously determined via an isotope measurement.

The computer's computer program now determines the solids content a in the mass flow Q tot from the equation:  Q tot out (measured in e.g. t / h = c1 (known) x a + c2 (be knows) × b (measured).

The outgoing mass flow Q tot is thus complete Are defined: The proportion a of solids is calculated.

The proportion b (moisture) is measured.

c1 and c2 are known material constants.

The total amount is measured.

The computer program can use the controlled variable "r" constant and defined conditions in the mass flow Q Tr to manufacture. This is done by solving the equation system systems: Mass flows

Q org (t / h) + Q tot out x r (t / h) = Q Tr on (t / h)

and Solid components

(a x c1) x r + X x c1 = a x c1.

As a result, each value X (variable solids content in Q org) a control value "r" can be assigned. This assignment takes place at infinitesimal computer speed.

Since the mass flow Q org (t / h known from measurement) on ei n is kept constant, results from Sub traction and solution of the systems of equations  Mass flows:

a1) Q org (m³ / h) = const = X x c1 + Y x c2 and
a2) Q org (t / h) = known = X x c1 + Y x c2

and the component relationships

b) X x c1 + r (ax c1) = ax c1 and
c) X x c1 + Y x c2 + r (Q tot off) = ax c1 + bx c2 - (Y - b) x c2

a clear solution of the relationship Y to r in z. B.%. It are three systems of equations a1 / 2, b, c and three variables X, Y and r with a defined ratio X / r. That glide system is determined.

A desired, pre-selected and qualified festival Substance / liquid ratio in the outgoing mass flow Q total moisture content can thus reach any moisture content Y im Inlet mass flow Q org immediately adds "r" for the second mass flow in z. B. t / h can be assigned. This Result is achieved without a continuous solids or perform moisture measurement in the input mass flow have to.

Claims (2)

1. A method for producing and maintaining a pre-selectable qualified solid / liquid ratio in a non-flowable, difficult to pump paste and / or sticky mass flow or the like. With permanently variable proportions of liquid component to solid component, preferably sewage sludge, characterized in that the mass flow is permanently fixed in volume and mass, and that this input mass flow is metered to form an outgoing mass flow having the desired solid / liquid ratio and a second mass flow with a high solids content is metered, the solid / liquid ratio of the second mass flow being known or easily measurable is and wherein the solid composition of the second mass flow corresponds to that of the input mass flow, and that the solid / liquid ratio of the outgoing mass flow is measured continuously , And that this measured value is used together with the amount of the input mass flow and the known weights of the solid and liquid portion of the input mass flow for arithmetic determination of the amount of the second mass flow to be supplied, and that the amount of the added second mass flow through the computer output signal is determined. 2. The method according to claim 1, characterized in that the second mass flow from an external supply and / or taken from the outgoing mass flow and fed becomes.