SU1131510A1 - Hydraulic system for preparing and feeding dialyzing solution - Google Patents

Abstract

HYDRAULIC SYSTEM FOR PREPARATION AND SUPPLY OF DIALYING SOLUTION, containing a cold water source, its preparation system including a filter, pressure reducer and heater, sources of concentrated salt solutions with connecting lines, a mixing tank with a pressure sensor, water pressure sensors in the line and a supply tank with a preheater, characterized in that, in order to increase reliability, simplify the design and reduce the pressure pulsation of the dialysis fluid, each source of concentrated the left solution is made in the form of an osmotic cell, which is a closed tank divided by height. two parts of a semipermeable membrane, one of the parts of the tank is connected to a source of cold water, and the other is filled with a saturated salt solution, in which salt is placed in the solid phase, a bellows is installed on the output lines of the sources of concentrated salt solutions, which has a capillary on the free end, between the heater and the mixing tank, a choke is installed, (L and all the output lines of the sources of concentrated salt solutions are connected to it.

Description

The invention relates to medical technology and can be used in the development of hemodialysis systems for the treatment of patients with acute and chronic renal failure under conditions of nephrology centers and laboratories "Artificial Kidney.

The closest technical solution to the invention is a hydraulic system for preparing and supplying a dialysis solution containing a cold water source, a preparation system including a filter, a pressure reducer and a heater, sources of a concentrated salt solution with connecting pipes, a mixing tank with a pressure sensor, pressure sensors water and concentrated solution, consumable tank with heater 1.

The disadvantages of this dialyzer are relatively low reliability due to the structural complexity of the system for preparing and controlling the composition of the dialysate, as well as pressure pulsations caused by the discreteness of the diluted solution. The purpose of the invention is to increase reliability, simplify the design and reduce the pressure pulsation of the dialysis fluid.

The goal is achieved by the fact that in a hydraulic system for preparing and supplying a dialysis solution containing a source of cold water, its preparation system, including a filter, a pressure reducer and a heater, sources of concentrated salt solutions with connecting pipes, a mixing tank with a pressure sensor, water pressure sensors in the main line and consumable tank with a heater, each source of concentrated brine is made in the form of an os.motic cell, which is a closed reservoir, divided into two parts by a semipermeable membrane, one of the parts of the tank is connected to a source of cold water, and the other is filled with a saturated salt solution, in which salt is placed in the solid phase, on the output lines of the sources of concentrated salt solutions is installed a bellows the free end of the capillary, a choke is installed between the heater and the mixing tank, and all the output lines of the sources of concentrated salt solutions are connected to it.

FIG. 1 shows a schematic of a dialyzer (hydraulic system for preparing and supplying a dialysis fluid “Artificial kidney); in fig. 2 - osmotic cell device and its connection to the choke in the cold water line.

The source of cold water 1 (Fig. 1) is connected in series with filter 2, gearbox 3 (tap water pressure regulator), heater 4 and throttle 5

5 to which osmotic cells 8 are connected through the bellows 6 and the capillaries 7. The output of the throttles 5 is connected to the mixing tank 9 on which the pressure switch 10 and the pressure sensor 11 are installed, solenoid valves 12 and 13, to the output of which, depending on the operating mode supply tank 14 is connected to an individual post dialysis 15.

Osmotic cells 8 through the bypass line 16 are connected to a source of cold

5 water 1. Water pressure sensors are installed in the water line 17. A saturated aqueous solution of salt is located in the bellows 6 and in the tank 18 (Fig. 2), which communicate with each other. The container 18 contains salt 19 in the solid phase and is separated from the container 20 with water by a semi-permeable membrane 21.

The hydraulic system for the preparation and supply of dialysis fluid (FIG. 1) works as follows.

From source 1, cold water enters the filter 2, which is designed to purify water from mechanical particles larger than 30 microns, and pressure reducer 3, which maintains the pressure of water on

Its output is 1.5 kgf1cm. Water from the gearbox enters the heater 4, where its temperature rises to 36-49 ° C, and then to choke 5. A saturated salt solution through the bellows 6 and capillary 7 comes from osmotic cells. In throttle 5, a saturated solution of the salt of C. is mixed with water and enters the mixing tank 9. In the mixing tank, the water and the saturated solution are completely mixed, forming a dialysis solution, which

0 through an open electromagnet:; valve 11 at an excess pressure of 0.2-0.3 kgf / cm, measured by sensors 11, enters the dialysis line to power individual posts 15. Pressure switch 10 blocks the solution from entering the tank 9 at increasing pressure in it. Higher than 0.3 kgf / cm. The solenoid valve 13 in the dialysis mode is closed, in the sterilization mode it opens and the water through it and through the supply tank 14 is supplied

0 to individual posts 15.

The osmotic cell works as follows (Fig. 2).

Upon contact of saturated .water

salt solution with water through the membrane 21,

5 water permeable and impermeable

salt hell, osmotic flow occurs

water pressure:

P CRT,

where C is the molar concentration of forces in water;

R is a universal gas constant;

T is the temperature.

. Under pressure of osmotic forces, water passes through a semipermeable membrane 21 into a container 18 with a solution. To maintain the concentration of the solution at a saturation level at a given temperature, the solution is contacted with salt 19 in the solid phase. So, for example, at T 288 K for a saturated solution in water, the osmotic pressure can reach 136 at.

The concentration of salt in the solution takes place until the entire supply of solid salt is exhausted 19.

Due to the fact that the membrane 21 can be permeable to salt in small quantities, to maintain the salt concentration in the tank 20 with near-zero water, a flow of WATER is created through the tank 20 from the cold water bypass line 16.

The concentration of salt and pressure in the dialysing solution line is ensured by the constant concentration of the saturated salt solution and the constancy of the flow of the solution in the throttle 5. The flow of the saturated solution is determined by the surface and specific permeability of the selectively semi-permeable membrane 21. Therefore, for selected geometries and the membrane material, as well as the concentration temperature and flow rate, are constant. The temperature of the osmotic cell 8 is ensured by the fact that tap water within the season slightly changes its temperature, therefore the vessel with running water is a thermostat.

The pressure reducer 3 in the water line maintains well the outlet pressure while slowly changing the inlet pressure. However, a rapidly varying inlet water pressure can cause a change in the flow rate of water through the choke 5. In this case, the concentration of the dialyzing solution remains almost unchanged due to the fact that an increase in the flow rate will increase the flow of the solution (proportional leakage of the solution will occur in accordance with the Bernoulli equation) and, the reduction of the flow of water through the choke 5 will lead to a proportional decrease in the flow of the solution.

The concentration of the solution in the throttle is maintained most efficiently when selecting the flow area from the condition

 Q is the volume flow of water; p is the density of water; p is the excess water pressure at the inlet of the throttles.

Dialysis solution should contain, g: NaCl 5,7; COP 0.19; CaCUO, 33; CHjCOONa (sodium acetate) 3.28 per liter of solution.

Considering that the concentration of a saturated aqueous solution of salts at tap water temperature T 284K is 358 g / l for NaCl, 651 g / l for CaCli, 312 g / l for KC1, 410 g / l for NaCHjCOO and the minimum consumption of dialysis solution 8 l / min (through the throttle volumetric

5 water consumption 8 l / min), then the volumetric flow of saturated salt solutions coming from the osmotic cells is: l / min: NaCl 0.022; CaCl20.012; KCl 0.005; HaSNSOO 0.064. The indicated flow rates are provided using native acetate cellulosic membranes, e.g., MHA-80. The permeability of the MGA-80 membrane is 600 l / s.m per day, or 0.4 l / m min. for osmotic cells with saturated solutions of NaCl, KCl, CaClj, NaCHjCOO.

0 Naturally, a membrane in the form of a tube can be used if it becomes necessary to increase the flow rate of the dialysate and reduce the size of the osmotic cell. In this case, the surface of the selectively permeable membrane can be significantly increased. During long-term operation of the proposed system, the concentration of the dialyzing solution is almost constant, the deviation from the specified value does not exceed ± 2% (in the prototype, the concentration varies within ± 6%). There are no pressure pulsations in the proposed system, they could not be registered using a recording manometer; in the prototype, pressure pulsations in the water line

 exceed 25% of the absolute value of the pressure.

The implementation of the proposed device in the practice of medical engineering and instrumentation will allow to obtain a significant economic effect by reducing the cost of production, increase reliability, lack of pulsations and improve the accuracy of maintaining the concentration of dialysis solution, eliminating complex control

5 and controlling proportional pump automatic equipment. Reliability is improved, since in the proposed apparatus there are no moving

details and reduced the number of nodes (elements) of the system for the preparation of dialysis tsegs) solution, leading to a simplified design. It eliminates the need to incorporate deaeration units into the system, reduces energy costs, since the salt dissolution energy is mainly used.

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Claims (1)

A HYDRAULIC SYSTEM FOR PREPARATION AND DELIVERY OF A DIALYSING SOLUTION, containing a source of cold water, a system for its preparation, including a filter, a pressure reducer and a heater, sources of concentrated salt solutions with connecting lines, a mixing tank with a pressure sensor, water pressure sensors in the pipes and a supply tank with a heater, characterized in that, in order to increase reliability, simplify the design and reduce the pressure pulsation of the dialysis solution, each source of concentrated salt The solution is made in the form of an osmotic cell, which is a closed reservoir, divided by a height of. two parts with a semipermeable membrane, one part of the tank is connected to a source of cold water, and the other is filled with saturated brine, in which salt is placed in the solid phase, a bellows is installed on the outlet lines of the sources of concentrated brine, which has a free _ end a capillary, a choke is installed between the heater © and the mixing tank, and all output lines of sources of concentrated salt solutions are connected to it. FIG. 1