RU2838240C1 - Method of preventing formation of scale on nozzles spraying water in high-temperature gases - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to heat engineering and can be used for protection against scale of nozzles spraying water in zone of gaseous medium of high temperature of contact heat exchangers and other process equipment. In the method, water is sprayed into the zone of the gaseous medium, having a temperature higher than the boiling point of water at the pressure of the gaseous medium, coating of nozzles with a layer of water insulating them from gases, through which spraying is carried out, wherein the mass flow rate of the sprayed water is determined during the nozzle operation mode adjustment upon achieving a stable output of the sprayed water from the insulating water layer with no separation of the insulating water layer from the nozzle surface, wherein diameter of holes for sprayed water outflow from nozzle is smaller, while density of said holes on nozzle is larger than values causing separation of protective layer of water from nozzle surface.

EFFECT: improving operating reliability of nozzles by preventing formation of scale on them and avoiding the need to shutdown equipment for cleaning nozzles from scale.

3 cl, 7 dwg

Description

Field of technology

The invention relates to thermal power engineering and can be used to protect nozzles spraying water in the high-temperature gaseous medium zone of contact heat exchangers and other process equipment from scale.

State of the art

The use of nozzles spraying water in the zone of a high-temperature gaseous medium is associated with partial boiling of water on the surface of the nozzles, which leads to the deposition of insoluble scale-forming salts on the nozzles, their clogging and deterioration of spraying. This requires cleaning the nozzles in various ways, including periodic shutdown of the device where the nozzles are installed.

There are known methods in which, in order to prevent scale, water is pre-treated by chemical water treatment, filtration or reverse osmosis (RU Patent for Invention No. 2220913), various reagents are introduced (RU Patent for Invention No. 2378562 and No. 2637036), and electric, magnetic and/or acoustic fields are used (RU Patent for Invention No. 2312290, 2355973, 2599734, 2503747, 2599734, 2124686, 2779101).

However, these methods are not effective enough to prevent scale build-up on nozzles that spray water in a high-temperature gaseous environment.

A method is known for reducing scale formation by using circular turbulent movement of the coolant in the heated elements of a hot water boiler. (RU Patent No. 2200913, IPC F24H 1/40, published 20.03.2003).

A method of contact heating of a liquid is known (see Russian patent No. 2662260, IPC F24H 1/00, published 09.11.2017), in which the heating gas is supplied to the flue from above, while the amount of supplied heating gas is selected to be smaller, and the amount of heated liquid is greater, causing an increase in the temperature of the inner surface of the flue to the temperature of scale formation on it.

A method of contact heat exchange is known (see Russian Federation Patent No. 2619429, IPC F24H 1/00, published on 15.05.2017), including heat exchange between gaseous products of fuel combustion and the surface of the liquid, in which heat exchange is organized by contact of the thermal field of the torch with water in a droplet state through the primary accumulation of all the energy of the torch in the evaporation of droplets of a part of the water in the volume of ~4.7% of the total mass of the heated water and subsequent intensive energy exchange of the resulting steam-gas mixture by adhesive-condensation heat exchange with droplets of the main mass of water in the volume of ~94.3%. At the same time, the requirements for the quality of feed water are reduced in terms of scale formation on the heating surfaces, since the heating surface is water droplets and the scale is formed in the form of sludge removed by blowing.

However, the above methods are not intended to prevent scale formation on nozzles that spray water in a high-temperature gaseous environment.

Disclosure of the essence of the invention

The technical problem of the present invention is the development of a reliable and low-cost method for preventing the formation of scale on nozzles spraying water in high-temperature gases having a temperature higher than the boiling point of water at the pressure of these gases.

The technical result of the claimed invention is to increase the reliability of the nozzles by preventing the formation of scale on them and eliminating the need to stop the equipment to clean the nozzles from scale.

To achieve the technical result, the method for preventing scale formation on nozzles includes spraying water with nozzles into the zone of a gaseous medium having a temperature higher than the boiling point of water under the pressure of the gas medium, covering the nozzles with a layer of water that insulates them from gases, through which spraying is carried out. The insulating layer of water is created by direct mutual irrigation with another/other nozzles or by creating a layer of water flowing onto the nozzles on the inner surface of the housing.

Brief description of the drawings

The invention is illustrated by figures 1-6, which show examples of the operation of water nozzles inside the housing of the device with a high-temperature gaseous medium without scale formation, according to the present invention.

The positions indicate:

1. Body;

2. Nozzle;

3. Water supply to the nozzle;

4. Spray water from the nozzle;

5. Insulating layer of water on the nozzle;

6. Layer of water on the body;

7. High-temperature gas zone.

8. Water for direct irrigation of the nozzle;

9. Test stand support frame;

10. Gas water heater;

11. Automated gas burner Hansa HSP1.1F with built-in safety automation, heat power and air supply regulators;

12. Cylinder (50 l, working pressure 16 bar) with propane-butane mixture;

13. Exhaust chimney;

14. Water pipelines;

15. Pipeline for removing condensate from flue gases;

16. Fan heater GREERS VS-2365;

17. Pump WILO PB-400-EA;

18. Inlet manifold for supplying water to the nozzles;

19. Water consumption meter.

Figures 1-3 show an example of the operation of water nozzles inside the housing of a device with a high-temperature gaseous medium without scale formation, according to the present invention, with the nozzles coated with a layer of water that insulates from gases by creating a layer of water flowing onto the nozzles on the inner surface of the housing, through which the nozzles spray. The creation of a water layer on the inner surface of the housing is carried out under the action of centrifugal forces and requires, in order to prevent the water layer from separating from the surface of the housing, a curved shape of the inner surface of the housing in the zone of movement of the water layer.

Figures 4-6 show an example of the operation of water nozzles according to the present invention, with the nozzles coated with a layer of water that insulates from gases, through which spraying is carried out, due to direct mutual irrigation of the nozzles without creating a layer of water flowing onto the nozzles on the inner surface of the housing. In this case, the requirements for the shape of the inner surface of the housing are removed.

Implementation of the invention

The method is intended for use in contact heat exchangers and other process equipment in which water is sprayed by nozzles in the zone of a gaseous medium having a temperature higher than the boiling point of water at the pressure of these gases.

The prevention of the formation of insoluble scale deposits on the nozzles is achieved by creating an insulating layer of water on them through mutual irrigation, due to the fact that the surface temperature of the nozzles is lower than the boiling point of water, since the heat flow is directed from the hot gaseous medium to the nozzles, through the layer of water covering them with a temperature no higher than the boiling point of water, and, on the other hand, due to the cooling of the nozzles to a temperature lower than the boiling point of the water flowing through them. However, boiling of the water layer is possible, with sufficient heat flow and gas temperature, only on the surface of the water layer covering the nozzles from the side of hot gases with the formation of scale in the form of a finely dispersed insoluble suspension in boiling water, which is removed, as it is formed, from the lower points of the body 1. The mass flow rate of the sprayed water from the nozzle is determined in the process of mode adjustment of the operation of the nozzles to achieve a stable output of the sprayed water from the insulating layer of water in the absence of separation of the insulating layer of water from the surface of the nozzle.

One of the embodiments of the method (Fig. 1-3) is implemented as follows.

Spraying (spraying) of water inside the cylindrical or cone-shaped, or other outwardly curved shape of the body 1 of the heat exchanger with the gaseous medium 7 is carried out using nozzles 2, located uniformly or otherwise along the perimeter of the body. Water is supplied to the nozzles 2 by pipes 3. The nozzles are located so that the water sprayed by the nozzle covers the adjacent nozzle with a layer of water by creating a layer of water 6 flowing onto the nozzle on the inner surface of the body due to its exit from another nozzle along the inner surface of the body. Thus, each nozzle will be covered with an insulating layer of water 5 due to its irrigation by another nozzle/nozzles. Irrigation of gases by the nozzle will be carried out through this layer of water 5, which allows the surface of the nozzle to be removed from the gas zone 7.

In another embodiment (Fig. 4-6), the insulating layer 5 is created by direct mutual irrigation of the nozzles with water jets 8, without creating a layer of water flowing onto the nozzles on the inner surface of the housing, exiting the nozzles into the gas zone 7 and directed at the cooled nozzles 2.

The method claimed in the present invention was tested on an experimental model of a contact-type gas water heater (Fig. 7) with a thermal power of 30 kW.

The test bench consists of:

- support frame 9;

- gas water heater 10 with a connected automated burner Hansa HSP1.1F 11 with built-in safety automation, heat output and air supply regulators;

- propane cylinder 12 (50 l, working pressure 16 bar) with propane-butane mixture;

- exhaust flue 13;

- water pipelines 14;

- pipeline 15 for removing condensate from flue gases;

- a coolant circulation circuit between a gas water heater 10 and two GREERS VS-2365 fan heaters 16 with a WILO PB-400-EA pump 17, supplying water to the nozzles through a manifold 18, and a water flow meter 19.

Artesian water was used as the source water.

It has been shown that the method according to the present invention effectively prevents scale formation on the surface of the nozzles. The diameter of the holes for the flow of sprayed water from the nozzle should be smaller, and the density of the arrangement of these holes on the nozzle should be greater than the values causing the separation of the protective layer of water from the surface of the nozzle. Experimental confirmation of the expected efficiency has been obtained.

The efficiency of the method was assessed visually based on the condition of the surface of the water heater nozzles. Before the tests, the nozzles were inspected and the initial condition of their surface was recorded. The inspection revealed no contamination of the nozzles. The tests lasted for 3 days. Inspection of the nozzles after the tests also showed no traces of scale deposits. Thus, the claimed method for preventing scale formation on nozzles spraying water in high-temperature gases is efficient and effective.

The method disclosed in this description has the following advantages: reduced scale formation on operating equipment; no need to use additional equipment and consumable chemical reagents.

Claims (3)

1. A method for preventing scale formation on nozzles located on a concave internal shape of a contact heat exchanger body and spraying water in high-temperature gases, comprising spraying water with nozzles into a zone of a gaseous medium having a temperature higher than the boiling point of water at the pressure of the gas medium, covering the nozzles with a layer of water that insulates them from the gases, through which spraying is carried out, wherein the mass flow rate of water sprayed by the nozzle is determined in the process of mode adjustment of the operation of the nozzles upon achieving a stable outlet of the sprayed water from the insulating layer of water in the absence of separation of the insulating layer of water from the surface of the nozzle, wherein the diameter of the holes for the outflow of the sprayed water from the nozzle is smaller, and the density of the arrangement of these holes on the nozzle is greater than the values that cause separation of the protective layer of water from the surface of the nozzle. 2. The method according to item 1, wherein the isolating layer of water is created by direct mutual irrigation with another/other nozzles. 3. The method according to item 1, in which the insulating layer of water is formed by creating a layer of water flowing onto the nozzles on the inner surface of the housing.