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EP-4737731-A1 - STEAM COMPRESSOR

EP4737731A1EP 4737731 A1EP4737731 A1EP 4737731A1EP-4737731-A1

Abstract

Centrifugal steam compressor (100), having one or more compression stages (100A, 100B) and provided with: - a gear multiplier (1) equipped with a plurality of shafts (13) that rotate with respect to a rotation axis (X), - at least one impeller (2A, 2B) supported by the shafts (13) and suitable for compressing steam coming from a pipe with a suction flange (14), - a first plate diaphragm (3) rigidly connected to the multiplier (1) with a thermal barrier (23) in between to minimize heat exchange, - a second (5A) and a third diaphragm (5B) rigidly and fluidly connected to the diaphragm (3) and in proximity to the at least one impeller (2A, 2B), - a casing (8) elastically mounted with respect to the third diaphragm (5B) and which is free to expand and move with respect to the third diaphragm (5B) by means of appropriate elastic elements (25) configured to ensure the seal among zones with different pressure levels.

Inventors

  • GAIA, MARIO
  • BINI, ROBERTO
  • MARIOTTI, GABRIELE

Assignees

  • Turboden S.p.A.

Dates

Publication Date
20260506
Application Date
20251014

Claims (10)

  1. Steam compressor (100), centrifugal, having one or more compression stages (100A, 100B) and comprising: - a gear multiplier (1) provided with a plurality of shafts (13) rotatable, with respect to a rotation axis (X), - at least one impeller (2A, 2B) supported by the shafts (13) and suitable for compressing steam coming from a pipe with a suction flange (14), - a first plate diaphragm (3) rigidly connected to the multiplier (1) with a thermal barrier (23) interposed to minimize the heat exchange, - a second (5A) and a third diaphragm (5B) rigidly and fluidically connected to the diaphragm (3) and in proximity to the at least one impeller (2A, 2B), the compressor being characterised by the fact that it comprises a casing (8) elastically mounted with respect to the third diaphragm (5B) and which is free to expand and move with respect to the third diaphragm (5B) by means of appropriate elastic elements (25) configured to ensure the seal between zones with different pressure levels.
  2. Compressor (100) according to claim 1 comprising a plurality of atomized water sprayers (6), located downstream of the second (5A) and third diaphragm (5B) and downstream of the at least one impeller (2A, 2B), the plurality of sprayers (6) being arranged circumferentially with respect to the axis (X) and fed by ducts (17).
  3. Compressor (100) according to claim 2, further comprising a circumferential distributor (18), fluidically connected to the ducts (17) and provided with one or more inlet channels (19) for the attempering water.
  4. Compressor (100) according to claim 3, further comprising a plurality of compartments (4) rigidly connected to the first diaphragm (3) with one or more holes fluidically connected to the ducts (17) and to the distributor (18).
  5. Compressor (100) according to anyone of claims 2 to 4, wherein the nozzles (6) are mounted inside a delivery plenum (16).
  6. Compressor (100) according to claim 5, further comprising a plurality of rectifier compartments (26), upstream of the delivery plenum (16) and fluidically connected to the diffuser (22) of the at least one or more compression stages (100A, 100B).
  7. Compressor (100) according to claim 5 or 6, wherein the delivery plenum (16) is fluidically connected to the outlet of the second (5A) and third diaphragm (5B) and to the sprayers (6) so as to create a calming chamber upstream of a delivery nozzle (9).
  8. Compressor (100) according to claim 7, wherein the delivery plenum (16) is fluidically connected to a drain (20) to collect an excess of attempering water.
  9. Compressor (100) according to anyone of claims 2 to 8, wherein the sprayers (6) are configured to inject water with finely distributed drops and having an average diameter of less than 50 microns.
  10. Compressor (100) according to anyone of the preceding claims, further comprising a suction nozzle (11) with radial or diagonal orientation, i.e. not parallel to the rotation axis (X).

Description

Technical sector of the invention The present invention relates to a steam compressor, specifically a multistage centrifugal compressor. More specifically, the compressor according to the present invention could have an operating pressure between 0.2 bar and 12 bar and be used in industrial processes with heat pumps or for the mechanical compression of steam in general. Backgroung art Mechanical vapor compression, often referred to by its acronyms in english MVR (Mechanical Vapor Recompressor) or MVC (Mechanical Vapor Compression), involves compressing a vapor flow to raise its pressure and, possibly, its temperature, by means of a positive displacement machine or a turbomachine. The latter ones increase the vapor pressure by increasing the energy imparted to the fluid by one or more impellers driven by a prime mover. In this process, the vapor increases its enthalpy content, resulting in an increase in both pressure and temperature. As is known, the pressure head, or the specific energy required to compress a vapor, and consequently the power absorbed by the machine, is proportional to its temperature. For this reason, multistage compressors and fans are often used in vapor compression, for example with multiple impellers, equipped with devices to cool the vapor flow, such as exchangers or interphase attemperators (also called desuperheaters), to reduce the vapor temperature and consequently the compression power. Specifically, attemperators can be realized by injecting liquid water, which, upon evaporation, reduces the temperature of the superheated fluid by exploiting its latent heat of vaporization. Compressors with such attemperation systems are divided depending on whether the water injection is carried out in the piping system connecting the various compression stages or directly inside a compression stage. Documents EP4170186A1 from Siemens Energy, CN111749932A from the China Institute of Aerodynamics, or CN107559239B from Beijing University describe the state of the art for the construction of spray-based attemperation systems within the compression stage, specifically with injection performed immediately upstream of the first compressor impeller. This solution is also widely used when compression is performed by centrifugal fans, also known as fans or blowers. Other systems involve attempering by means of suitable de-superheaters installed on the pipes that fluidly connect each compression stage. These include sprayers mounted as shown in Fig. 1, taken from the catalogue of the Schutte&Koerting company, a manufacturer of steam attempering systems. Water injection, according to a known technique, is dosed to reduce the degree of superheat until conditions approaching saturation are reached. Generally, this practice results in a non-optimal design of the compressor and/or the piping system, as any excess condensate, for example generated by sudden changes in the flow rate to be attempered, is dragged by the vapor liquid flow into the compressor impeller, causing erosion or vibrations. If liquid water is injected immediately upstream of the impeller, liquid entrainment occurs regardless of the dose due to the liquid's passage times through the impeller, which in common practice are always shorter than the evaporation times. The erosion and vibration problems mentioned above are generated by the tangential forces due by the presence of liquid in the air gap between the rotating parts and their stators. It is known, in fact, that the contact of liquid water with the compressor impeller, having a peripheral velocity in the order of 200-400 m/s, induces strong tangential forces related to the viscous nature of the fluid and the velocity gradient to which it is subjected. The presence of liquid between a rotating part and its stator requires a significant increase in the air gap from a value of a few tenths to 3-5 mm (typical value used for fans) to avoid erosion and vibration, with obvious negative consequences on the stage's performance. It is known, in fact, that the efficiency of a centrifugal stage is negatively affected by the recirculation generated in the air gap between the impeller and stator parts, such as the casing or diaphragms. By injecting water onto the pipeline, it is possible to optimize the efficiency of the stage by reducing the air gap between the impeller and the rotor, ensuring that all the injected water evaporates before it reaches an impeller. The evaporation of the injected water occurs with a delay, also called residence time, which determines the length of the pipe, depending on the velocity of the steam in the pipeline. Generally, this length is much greater than the minimum length needed to connect two consecutive stages, with obvious disadvantages in terms of cost, compactness, and pressure drops. In any case, to ensure that no liquid water is entrained in the impeller, it is necessary to dose the quantity of liquid water by considering a margin compared to the exact amoun