DD159661A1 - DEVICE FOR FLUID FILLING WITH MINIMIZED COMPRESSIVE PRESSURE - Google Patents

Abstract

The device for conveying liquids with minimized compressible pressure medium quantity is used in the return of condensate by means of steam in heating technology and district heating supply as well as in the promotion of other liquids by compressed gaseous media. The invention has the goal to minimize the required pressure medium flow and thus to reduce the energy consumption, especially in partial load ranges. By a central control unit, which includes a microprocessor, the inlet and outlet valves for the pressure medium are controlled so that filling and expansion spaces are adapted to the respective loads automatically. Based on the filling times of the pressure medium of each ended delivery interval and the upcoming delivery task, the filling times for the following interval are gradually changed to achieve an energetically optimal operation. The device can be used at the same time for volume and mass determination of the pumped liquid.

Description

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application areas

The device for liquid delivery with minimized compressible pressure medium amount is used in heating technology and the district heating supply for the return of the resulting condensate during heating by means of steam. Other applications are given in the promotion of other liquids by compressed gaseous media, such as in the promotion of wastewater by means of compressed air.

Well-known technical solutions

After / 1 / a liquid and condensate conveyor is offered, which works according to the displacement principle. If the pressure chamber is filled to an upper liquid level, the inlet for the gaseous or vaporous pressure medium is released and pressed the liquid at a constant inlet pressure in the liquid delivery line. If a lower liquid level is reached, closes the inlet of the pressure medium and at the same time opens a vent valve, through which the gaseous or vaporous medium conveyed auf'ein low pressure level -. Atmosphere with pumped air - can flow out and thus new liquid can enter the liquid conveyor. The inlet pressure of the liquid must, of course, above the low pressure level against which the spent fluid flows out, are "disadvantages of the system that the liquid flow in the delivery container must not fall below a minimum value.

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since the upwardly moving float at a certain minimum speed the inlet valve must open jerkily and the load during the promotion always the full admission pressure of the fluid on the liquid. This means that even at partial load, the promotion is made with the same energy consumption as at full load. The practically workable filling time ranges specified by / 1 / are such that in heating technology the required load ranges of approximately 100%, 10% (5%) can not be achieved with one apparatus.

To circumvent the aforementioned disadvantages, a conveyor with electronic control and minimized quantity of the pumped medium is presented below.

Object of the invention

The invention serves the purpose of controlling the promotion of liquids by means of vapor or gaseous media according to the displacement principle so that only the minimum necessary amount of the pumped medium in dependence of the flow rate and the real existing pressures must be used.

Essence of the invention .

The invention is based on the object, using a controller by means of microprocessors, the amount of vapor or gaseous medium to be optimally adapted to the loads. The solution to this problem will be explained below with reference to FIG.

It is assumed that the container 1 is filled up to the upper liquid level LC 1 with the liquid to be delivered. The normally open solenoid valve 3 is closed and the normally closed solenoid valve 2 is opened. As a result, the fluid flows in. First, the dead space is brought to the filling pressure of the vapor or gas p _F , then the displacement of the liquid begins by opening

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of the check valve 4 in the region of the filling volume Vp, After reaching the predetermined filling time T _p , the solenoid valve 2 closes off the inflow of the pumped medium. Thereafter, the liquid delivery takes place with a time-decreasing intensity due to the expansion of the medium in the container 1 to the liquid level LC 2 »This space is referred to as expansion volume V_. Upon reaching the liquid level LC 2, the promotion of the liquid by opening the solenoid valve 3 and the associated pressure decrease in the container 1 is terminated. The spent fluid flows against the discharge pressure p. out. It is from the inflowing liquid, which is under pressure pen

> p. is up to the level LC 1 ejected. Thereafter, a new delivery interval begins, whereby the promotion can be accelerated or delayed by the filling time TTp is changed by a time step AV . This value At can be predetermined or it is independently calculated by means of a program by a microprocessor. Decisive for this is the fluid level in the reservoir 7. If it is above the setpoint LC 3, then the filling time must be extended by Ax ; If it is below the target value LC 3, the filling time is shortened by At , the filling and expansion volumes are shifted due to the changed filling time, but their sum remains constant due to the given container geometry. Did the pressure conditions suddenly change, or was the Filling time is wrong, so two extreme cases are conceivable, If the filling time is too large, the filling volume is extended to LC 2. Simultaneously with the opening of 3, the inlet 2 is then closed. If the filling time was too small, the final pressure occurring during the expansion could no longer be sufficient to displace the liquid to the level LC 2. If this lower limit fluid level was not reached within a predetermined time difference after closing the intake valve 2-for example 3 * T _p- then two counterreactions are possible

 If the primacy lies in energy saving, then that should be

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Outlet valve 3 is opened and the filling time is increased by & X during the subsequent delivery interval. Is priority to ensure the volume measurement by counting the liquid quantities, then the inlet valve 2 is opened to reach the lower water level LC 2 and the Füllzeitvorgabe increased by also Af, this backlash may occur repeatedly. If, for the first time, a liquid delivery of LC 1 to LC 2 with a filling of the delivery medium takes place, then a fixed number of delivery intervals - for example 10 to 20 - should be passed through without again shortening the filling time, even if the reference value LC 3 is undershot. Only then is it tried again, whether a lesser use of the pumped medium is sufficient for complete displacement of the liquid,

Flows from the sump 7 only a very small liquid flow, which may also be temporarily interrupted, in the container 1, so the filling time is extended, after reaching the level LC 1, the return promotion takes place, however, unchanged as described above.

EXEMPLARY EMBODIMENTS

The condensate of a Dampfve'rbrauches should be conveyed back by means of vapor pressure through a device according to the invention to the heat supplier. The pressures are at full load / part load

Filling pressure of the steam: P _F / pp

Blow-out pressure of the steam: P ^ / Pa

Constant back pressure in the condensate line: P _g / Pq

The volume expansion of the pressure medium takes place after the polytropic change of state ρ V ⁿ «= const" At full load, a filling volume Vp "extending between the liquid levels LC 1 and LC 2 can be assumed.

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It is the conditions at partial load, for example, when 10% of the full-load condensate incurred to investigate. The conveyor is designed so that the dead space is negligible. The time for a condensate filling due to the flow of container 7 in the container 1 is due to the geodetic height differences and the constant discharge pressure p »unchanged for all occurring load cases τ _FF « The technical switching times are summarized per delivery interval tg, they are also load independent.

Assuming that in the full load case, the condensate volume V * is to promote in the time interval T £, then follow from it

V ⁺ k ⁺ - ^K

^V F (1)

Delivery intervals, The total time for the overflow into the delivery container and the required switchover is

-Cl «V (T _FF + T ₈ ). (2)

This leaves filling time (an expansion should not occur at full load) per delivery interval

γ + i T ⁺

^h k ⁺ (3)

Since the pure liquid displacement is continuous, applies to the maximum condensate flow promoted

V ^{+ V} K

V ⁺

(4)

For this, the support line is to be measured. Based on the available differential pressure

Δρ ⁺ = Pp .- p _{G. (5)}

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the delivery line may have the resistance coefficient

respectively. This value applies approximately to all other loads »If the volume of condensate to be transported sinks to

S,

v _K. ο, ι v * ₍₇₎

in the time interval T _K »follow

k = 0.1 k ⁺ (8)

Delivery intervals and a maximum allowable filling and expansion time

tj-0.1 ti

(r _{F +} r _E ) _max -Ji-η-S, (9)

This maximum need not necessarily be exploited during the promotion, but merely represents the upper limit. The pressure conditions during filling and in the volume expansion are decisive. During the filling time t _p , the filling volume Vp is displaced, which results from the filling time and the almost constant Condensate flow according to Gl, (6) can be calculated

v = χ ν .r -i ^Pp " ^Pg

^{F F K F}

Thereafter, the volume expansion begins, wherein the pressure in the delivery container p _E and the funded volume flow V _{K represent} time functions. The expansion time until reaching the lower limit water level is then

^V F " ^V F

This clearly shows that with the choice of the filling time Tp the entire filling and expansion process is determined,

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ie by varying T _F , the delivery process can be clearly controlled and optimized.

Would be (τ _ρ + T _E ) ^ (Tp + T _E ) _χ , then increase in the container 7, the liquid level, T_ would be extended and r _∈ to Eq (II) greatly shortened, resulting in a larger flow rate.

At Pj ₁ [V _F / (V _F + V _E )] ⁿ = p_, the liquid delivery stagnates. After exceeding a predetermined residence time, the filling time is increased at the following Förderiqtervallen until the expansion proceeds to the lower liquid level. The resulting possible shortening of the delivery time (Tp + T ^) then leads to the emptying of the container 7 and necessarily extended flow time of the liquid in the container. 1

With most favorable tuning, the delivery time (Tp + Tp) · The filling volume V_ - divided by the specific

t IHuX ι

see vapor volume v _Q - gives the required vapor mass per delivery interval. They apply to the design case

m _n -

^{D v} S ( ¹² >

Of low demand

m _D = _; ,

- ^V D (13)

Claims (4)

230802 0 Erfindunqsanspruch 1. The device for conveying liquids with minimized compressible pressure medium quantity for energetically optimal delivery of liquids according to the displacement principle, wherein the amount of liquid to be conveyed and the pressure conditions are subject to very large temporal variations, characterized in that the pressure medium inlet (2) and the Druckmedienauslaß (3) at the pressure vessel (1) with auxiliary power, preferably with electric power, work and by a central control unit (6), which is equipped with a micro-, processor, so controlled that upon reaching the liquid level LC 1, even at very slower. Filling the container (1), the inlet valve (2) is opened and after a limited time filling T ρ closes again, during which time the liquid volume Vp and then due to the expansion of the pressure medium, the liquid volume Vp is displaced, and that upon reaching the Liquid level LC 2 via the central control unit (6) the opening of the outlet valve (3) is effected until liquid level LC 1 is reached, and that at the beginning of the subsequent delivery interval the filling time undergoes an optimal change by the filling time at a liquid level in the Collecting container (7) which is above the target value LC 3, extended by the time step At and at a liquid level below the setpoint LC 3 is shortened by At, the time step .DELTA.Τ fixed or benge as a ratio of each current feed Tpi preferably applies ΔΤ = Tp / 20, can be determined by the microprocessor, and there under extreme loading of the conveyor, the filling time V _p is gradually increased so that the filling volume extends Vp by the liquid level LC 1, until the liquid level LC 2, and that at minimum load the filling time Tp gradually shortened so that a maximum volume expansion of the print medium, and thus achieving a minimum energy input 230802 0 is, wherein exceeding the expansion time T ^ by a certain limit, preferably T = X.fpi leads to an opening of the outlet (3) before reaching the liquid level LC 2 and this at the subsequent delivery intervals an increase in the filling time Z- stepwise by Δτ as long as until the liquid level LC 2 was reached again by the expansion of the pressure medium for the first time and this optimal filling time a certain number of delivery intervals, preferably IO to 20, is maintained without renewed Füllzeitverkürzung, 2. Device according to item 1, characterized in that the change in the filling time Tp from the time of liquid flow between the liquid levels LC 2 and LC 1 is determined by an input function, so that with a shortened liquid filling, the filling time of the pressure medium increases and vice versa. 3. Device according to item 1 or 2, characterized in that when exceeding the predetermined expansion time Tr, the inlet valve (2) opens again until reaching the liquid level LC 2, so that at each delivery interval, the volume enclosed between .den water levels is promoted, and the number of delivery intervals is counted and the volume delivered during a predetermined time is calculated by the microprocessor and output via a visual display or a printer, 4. Device according to item 3, characterized in that at the liquid outlet of the container (1) is a temperature measurement and the microprocessor for an input function from the density determined and calculated by multiplicative linkage with the volume delivered the mass of the liquid and an optical display or a printer is output.