JP3883313B2

JP3883313B2 - Multi-effect absorption refrigerator

Info

Publication number: JP3883313B2
Application number: JP35683898A
Authority: JP
Inventors: 修行井上
Original assignee: 荏原冷熱システム株式会社
Priority date: 1998-12-16
Filing date: 1998-12-16
Publication date: 2007-02-21
Anticipated expiration: 2018-12-16
Also published as: JP2000179977A

Description

【０００１】
【発明の属する技術分野】
本発明は、多重効用吸収冷凍機に係り、特に、低温再生器から低温熱交換器を経由し、吸収器へ至る溶液ラインを改良した多重効用吸収冷凍機に関する。
【０００２】
【従来の技術】
高温再生器と低温再生器又は高温再生器と中温再生器と低温再生器とを有し、凝縮器、吸収器、蒸発器、熱交換器類等を主要構成機器とする二重効用又は三重効用吸収冷凍機の効率向上には、各熱交換器類の性能向上（熱回収の向上）が大きく寄与するのであるが、熱交換器の性能向上のため、熱交換器の伝熱面積の増大あるいは熱通過率の改良等を行うと、熱交換器の圧力損失（流動抵抗）が増大してしまい、特に、低温再生器から吸収器への流れが悪くなり、吸収サイクル形成ができなくなる。そこで、低温再生器から低温熱交換器への濃溶液ライン中に、濃溶液ポンプを設け、圧力損失に打ち勝てるようにしている。
このような濃溶液ポンプを備えた吸収冷凍機では、低温再生器の溶液流量の変動にかかわらず、濃溶液ポンブが一定速度で回転しており、ほぼ一定流量で運転することになり、冷凍機の運転条件によって低温再生器からの流出量が少なくなった場合に、濃溶液ポンプはキャビテーションを生じてポンプ故障を招く欠点があった。
【０００３】
この欠点を解消するための従来技術として、低温再生器から低温熱交換器までの間に液面リレーを設けて、液面低下時に濃溶液ポンプを停止させて、キャビテーション防止をするものが提案されている。
また、この欠点を解消するための別の従来技術として、低温熱交換器から吸収器への濃溶液ラインと、低温再生器から濃溶液ポンプまでのラインの間に、流路を設け、低温再生器からの流量が減少した場合、吸収器側から低温再生器側に溶液を流入させて、濃溶液ポンプのキャビテーション防止をするものが提案されている。
前記の濃溶液ポンプを液面リレーで発停させる方式では、濃溶液ポンプのキャビテーションを防ぐことはできるものの、濃溶液ポンプの発停に伴い、吸収器への濃溶液流量変動が大きく、冷凍能力の変動を大きくしてしまい、不安定な運転になる問題点を持っている。
【０００４】
一方、低温熱交換器から吸収器への濃溶液ラインと、低温再生器から濃溶液ポンプまでのラインの間に、流路を設ける方式では、低温再生器流量が少ないときは、吸収器側の、低温の濃溶液が低温再生器側に入り、低温熱交換器に入る濃溶液の温度を低下させ、熱交換器の能力を低下させてしまう。また、低温再生器からの流出量が多いときは、低温再生器側から吸収器側に直接流れてしまう濃溶液があって、吸収器側濃溶液の温度を高め、低温熱交換器の能力を低下させてしまう。この方式では、せっかく、低温熱交換器の性能を改善させようと大容量化しても、その効果を十分発揮できず、場合によっては、性能低下を招くこともあった。
【０００５】
【発明が解決しようとする課題】
本発明は、前述の問題点を解決し、冷凍能力の変動が少なく、低温熱交換器の性能低下もなく、熱効率もよく、経済的な多重効用吸収冷凍機を提供することを課題とする。
【０００６】
【課題を解決するための手段】
上記課題を解決するために、本発明では、再生器が少なくとも高温再生器と低温再生器を有し、吸収器から希溶波を送る１つの希溶液ポンプと、低温再生器から低温熱交換器類の入口を結ぶ濃溶液流路に設けた濃溶液ポンプとを有する多重効用吸収冷凍機において、前記希溶液ポンプ及び濃溶液ポンプに回転速度を調節する回転速度調節器を備えると共に、高温再生器の圧力を検出するセンサーを設け、該センサーの圧力の検出値の増減に従って、前記希溶液ポンプと濃溶液ポンプの回転速度をそれぞれ増減させて、溶液循環量を調整することとしたものである。
【０００７】
前記吸収冷凍機は、再生器が高温再生器と低温再生器又は高温再生器と中温再生器と低温再生器とからなる二重又は三重効用吸収冷凍機とすることができ、前記高温再生器の圧力を検出するセンサーは、高温再生器の圧力を直接検出する代りに、高温再生器と低温再生器との間の差圧、高温再生器と中温再生器との間の差圧又は高温再生器と吸収器との間の差圧か、又は、圧力に関連する物理量を検出することもでき、また、前記低温再生器の出口部に液面センサーを設け、濃溶液ポンプの周波数を増減させて、液面が該センサーの高位と低位の間にあるように制御する手段を有することもできる。
また、前記回転速度調節器は、ポンプ電源の周波数を調節するインバータ制御装置とすることができ、一つの制御装置で希溶液ポンプと濃溶液ポンプの両方を制御することができる。
【０００８】
【発明の実施の形態】
本発明は、多重効用吸収冷凍機において、高温再生器の圧力を検出するセンサーと、吸収器から高温再生器に希溶液を送る希溶液ポンプ及び低温再生器からの濃溶液流路に設けた濃溶液ポンプに、回転速度を調節する回転速度調節器とを設けたものであって、高温再生器の圧力を検出するセンサーを基に、希溶液ポンプの回転速度を調節すると共に、低温再生器からの流路に設けた濃溶液ポンプの回転速度を調節するようにしたものである。
本発明による多重効用吸収冷凍機では、高温再生器の溶液流出量を支配する高温再生器圧力を基に、高温再生器への溶液流入を流出量に対応させるように、希溶液ポンプの回転速度を調整しており、サイクル全体の溶液循環量が高温再生器圧力に支配され、低温再生器からの濃溶液流出量も高温再生器圧力に関連して増減する。
したがって、濃溶液ポンプの回転速度を高温再生器圧力を基に調節することで、低温再生器からの濃溶液流量に見合わせて、濃溶液ポンプを連続運転させることができる。また、低温熱交換器をバイパスさせることもなく、濃溶液ポンプのキャビテーション防止を図ることができる。
【０００９】
次に、図面を参照にして本発明を具体的に説明する・
図１は、本発明の吸収冷凍機の一例を示す概略工程図で、二重効用の例である。
図1において、Ａは吸収器、ＧＬは低温再生器、ＧＨは高温再生器、Ｃは凝縮器、Ｅは蒸発器、ＸＬは低温熱交換器、ＸＨは高温熱交換器、Ｐ１は希溶液ポンプ、Ｐ２は冷媒ポンプ、Ｐ３は濃溶液ポンプ、ＪはＪラインであり、１〜９は溶液回路で、１０〜１３は冷媒回路である。
また、希溶液ポンプＰ１を制御するため、圧力センサー２０と調節器２１を設け、濃溶液ポンプＰ３を制御するため、調節器２２を設けており、ａ１〜ａ４は濃溶液レベルを示す。
【００１０】
この装置の冷房運転において、冷媒を吸収した希溶液は、吸収器Ａから溶液ポンプＰ１により低温熱交換器ＸＬの被加熱側を通り、分岐して一部は高温熱交換器ＸＨの被加熱側を通り回路２から高温再生器ＧＨに導入される。高温再生器ＧＨでは希溶液は加熱熱源により加熱されて、冷媒を蒸発して濃縮され、濃縮された濃溶液は回路３を通り高温熱交換器ＸＨで熱交換され、回路６を通り低温再生器ＧＬからの濃溶液と回路５で合流する。一方、低温熱交換器ＸＬの被加熱側を通った希溶液の残部は、回路４から低温再生器ＧＬに導入され、低温再生器ＧＬは高温再生器ＧＨからの冷媒蒸気により加熱濃縮された後、回路５から濃溶液ポンプＰ３により、高温熱交換器ＸＬの加熱側を通った濃溶液と合流して、低温熱交換器ＸＬの加熱側を通り，回路９から吸収器Ａに導入される。
【００１１】
高温再生器ＧＨで発生した冷媒ガスは、冷媒回路１３を通り、低温再生器ＧＬの熱源として用いられた後、凝縮器Ｃに導入される。凝縮器Ｃでは、低温再生器ＧＬからの冷媒ガスと共に冷却水により冷却されて凝縮し、回路１２から蒸発器Ｅに入る。蒸発器Ｅでは、冷媒が冷媒ポンプＰ２により、回路１０、１１により循環されて蒸発し、その際に蒸発熱を付加側の冷水から奪い、冷水を冷却し、冷房に供される。
蒸発した冷媒蒸気は、吸収器Ａで濃溶液により吸収されて、希溶液となり希溶液ポンプＰ１で循環されるサイクルとなる。
濃溶液ポンプＰ３は、低温再生器ＧＬからの濃溶液流量を低温熱交換器ＸＬに導いている。
そして、希溶液ポンプＰ１と濃溶液ポンプＰ３とは、圧力センサー２０の信号により、調節器２１、２２により制御されている。
【００１２】
ａ１、ａ２は、高温再生器の濃溶液の溶液レベルで、ａ１は高位、ａ２は低位を示す。また、ａ３、ａ４は低温再生器の濃溶液の溶液レベルで、ａ３はオーバーフロー限界、ａ４は、キャビティ限界を示す。
オーバーフロー限界ａ３は、低温再生器の溶液が凝縮器Ｃに入り込む限界か、又は、Ｊラインの作動（溶液が低温熱交換器ＸＬ内で結晶した場合、Ｊラインを通して吸収器Ａに戻す）を示す。
具体的な溶液循環の制御については、図２〜図４を用いて説明する。
吸収剤／冷媒にＬｉＢｒ／Ｈ₂Ｏ系を用いる二重効用吸収冷凍機の場合、各機器の圧力は概略下記の通りである。圧力は、負荷状態、冷却水温度などで変動するので、幅を持たせて表示している。
蒸発器、吸収器：５〜１０ｍｍＨｇＡ、
凝縮器、低温再生器：２０〜５０ｍｍＨｇＡ、
高温再生器：２００〜７００ｍｍＨｇＡ、
【００１３】
図２〜図４は、図1に対応する流量関係を示している。希溶液循環量の内、低温再生器に５０％、残り５０％を高温再生器に流す場合を例示している。
図２は、高温再生器圧力と希溶液ポンプ流量の関係及び、高温再生器から低温再生器側に戻る量（圧力差を駆動力として戻るので、その戻り能力）を示している。
正確には、高温再生器と低温再生器との差圧を駆動力として流動するのであるが、低温再生器側の圧力が小さく、高温再生器の圧力を基に考えても差し支えない。図中、２本の線により、低温再生器側圧力が２０ｍｍＨｇの場合（ｂ）と、５０ｍｍＨｇの場合（ｃ）とを示している。
なお、高温再生器への希溶液流量ＶＧＨに対し、高温再生器からの濃溶液流量は概略０．８５〜０．９５ＶＧＨ程度となる。また、希溶液ポンプの流量ＶＰに対し、吸収器に戻ってくる濃溶液流量は概略０．８５〜０．９５ＶＰ程度となる。
【００１４】
図３は、希溶液ポンプの特性と、吸収冷凍機運転時の軌跡を示す。横軸には流量の他、ポンプ流量に対応する図２の高温再生器圧力（平均）を括弧内に示している。
この例では、下記の表１を基に希溶液ポンプの周波数を設定している。途中については、比例配分としている。より詳細には、高温再生器の出口部に液面センサーを設け、液面が高位ａ１になったときは、周波数を減少させてポンプ送り量を減らし、液面を回復させ、また、液面が低位ａ２になったときは、周波数を増加させてポンプ送り量を増し、液面を回復させるように制御している。
【表１】

【００１５】
図４は、濃溶液ポンプの特性と、吸収冷凍機運転時の軌跡を示す。破線で示す運転軌跡は低温再生器側の配管内液面位置（図1の高さh）をパラメータにした運転可能範囲であり、ａ４のキャビティション限界ｆとａ３のオーバーフロー限界ｇを示す。高温再生器圧力に対応して、表２にて濃溶液ポンプの回転速度を決めた場合の運転軌跡を太い実線ｄで示す。中間は、比例配分とする。
【表２】

【００１６】
運転可能範囲はかなり大きく、ある程度周波数設定がラフであっても、運転可能である。例えば、濃溶液ポンプを、希溶液ポンプと同じ電源周波数で運転すると、太い二点鎖線ｅのようになり、インバ−タ等の共用化は可能である。但し、別電源としておけば、表の修正で運転点をかなり自由に変更できるメリットがある。
なお、低温再生器の出口部に液面センサーを設け、液面が高位になったときは、周波数を増加させてポンプ送り量を増加させ、また、液面が低位になったときは周波数を減少させてポンプ送り量を減少させ、液面がセンサー間にあるように、液面を回復させるように制御しても差し支えない。
【００１７】
図５から図７は、本発明の他の吸収冷凍機の概略工程図を示し、図５と図６は二重効用、図７は三重効用の例である。符号はすべて図１と同じ意味を有する。図５においては希溶液は、吸収器Ａから溶液ポンプＰ１により低温熱交換器ＸＬと高温熱交換器ＸＨの被加熱側を通り回路２から高温再生器ＧＨに導入され、濃縮された濃溶液は回路３通り高温熱交換器ＸＨで熱交換され、回路４から低温再生器ＧＬに導入され、濃縮された後、回路５から濃溶液ポンプＰ３により、低温熱交換器ＸＬの加熱側を通り、回路９を通り吸収器Ａに導入される。他は図１と同様である。
【００１８】
図６では、希溶液は、吸収器Ａから溶液ポンプＰ１を通り分岐され、一部は高温熱交換器ＸＨの被加熱側を通り、回路２から高温再生器ＧＨに導入されて濃縮され、濃溶液回路３から高温熱交換器ＸＨ加熱側を通り、回路６から吸収器Ａに導入される。一方、分岐された残部は低温熱交換器ＸＬの被加熱側を通り、低温再生器ＧＬに導入されて濃縮された後、回路５から濃溶液ポンプ３により、低温熱交換器ＸＬの加熱側を通り、吸収器Ａに導入される。他は、図１と同様である。
図７は、三重効用であり、図１において高温再生器ＧＨと低温再生器ＧＬの間に中温再生器ＧＭが配備され、同様に熱交換器も高温と低温の間に中温熱交換器ＸＭが備えられ、中温熱交換器ＸＭの被加熱側を通った希溶液は分岐され、一部が中温再生器に残部が高温熱交換器の被加熱側に導入され、図１と同様に順次流れていく。
このように、図５〜図７の吸収冷凍機においても、図１と同様の効果を奏することができる。
【００１９】
【発明の効果】
本発明によれば、前記のように、冷凍機の効率改善のため、熱交換器の伝熱面積増大あるいは熱通過率の改良等を行い、熱交換器の圧力損失（流動抵抗）が増大しても、濃溶液ポンプの回転速度制御により、低温再生器からの濃溶液を、連続的に吸収器に戻すことができ、安定運転が可能である。
また、低温熱交換器にて再循環、あるいはバイパスする濃溶液もなく、低温熱交換器の能力を最大限に生かすことができる。
【図面の簡単な説明】
【図１】本発明の吸収冷凍機の一例を示す概略工程図。
【図２】図１における高温再生器圧力と流量の関系を示すグラフ。
【図３】図１における希溶液ポンプ特性を示すグラフ。
【図４】図１における濃溶液ポンプ特性を示すグラフ。
【図５】本発明の二重効用吸収冷凍機の別の例を示す概略工程図。
【図６】本発明の二重効用吸収冷凍機の他の例を示す概略工程図。
【図７】本発明の三重効用吸収冷凍機の一例を示す概略工程図。
【符号の説明】
Ａ：吸収器、Ｅ：蒸発器、Ｃ：凝縮器、ＧＨ：高温再生器、ＧＭ：中温再生器、ＧＬ：低温再生器、ＸＨ：高温熱交換器、ＸＭ：中温熱交換器、ＸＬ：低温熱交換器、Ｐ１：希溶液ポンプ、Ｐ２：冷媒ポンプ、Ｐ３：濃溶液ポンプ、Ｊ：Ｊライン、１〜９：溶液回路、１０〜１３：冷媒回路、１８：冷却水、１９：冷水、２０：圧カセンサー、２１，２２：回転速度調節器、ａ１〜ａ４：液面レベル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-effect absorption refrigerator, and more particularly to a multi-effect absorption refrigerator having an improved solution line from a low-temperature regenerator through a low-temperature heat exchanger to the absorber.
[0002]
[Prior art]
It has a high-temperature regenerator and a low-temperature regenerator or a high-temperature regenerator, a medium-temperature regenerator, and a low-temperature regenerator, and has a double effect or a triple effect mainly composed of a condenser, an absorber, an evaporator, a heat exchanger, etc. Improving the efficiency of the absorption chiller greatly contributes to improving the performance of each heat exchanger (improving heat recovery). However, to improve the performance of the heat exchanger, the heat transfer area of the heat exchanger is increased or When the heat passage rate is improved, the pressure loss (flow resistance) of the heat exchanger increases, and in particular, the flow from the low-temperature regenerator to the absorber is deteriorated, so that an absorption cycle cannot be formed. Therefore, a concentrated solution pump is provided in the concentrated solution line from the low temperature regenerator to the low temperature heat exchanger so as to overcome the pressure loss.
In an absorption refrigerator equipped with such a concentrated solution pump, the concentrated solution pump rotates at a constant speed regardless of fluctuations in the solution flow rate of the low-temperature regenerator, and is operated at a substantially constant flow rate. When the outflow from the low-temperature regenerator is reduced due to the above operating conditions, the concentrated solution pump has a drawback of causing cavitation and pump failure.
[0003]
As a conventional technique for solving this disadvantage, a liquid level relay is provided between the low temperature regenerator and the low temperature heat exchanger, and when the liquid level drops, the concentrated solution pump is stopped to prevent cavitation. ing.
In addition, as another conventional technique for solving this drawback, a flow path is provided between the concentrated solution line from the low temperature heat exchanger to the absorber and the line from the low temperature regenerator to the concentrated solution pump so that the low temperature regeneration is possible. It has been proposed to prevent cavitation of the concentrated solution pump by flowing the solution from the absorber side to the low temperature regenerator side when the flow rate from the vessel is reduced.
In the method in which the concentrated solution pump is started and stopped by the liquid level relay, cavitation of the concentrated solution pump can be prevented, but the concentrated solution flow rate fluctuation to the absorber is large due to the start and stop of the concentrated solution pump, and the refrigerating capacity It has the problem of increasing the fluctuation of the system and resulting in unstable operation.
[0004]
On the other hand, when a flow path is provided between the concentrated solution line from the low temperature heat exchanger to the absorber and the line from the low temperature regenerator to the concentrated solution pump, when the flow rate of the low temperature regenerator is small, the absorber side The low temperature concentrated solution enters the low temperature regenerator side, lowers the temperature of the concentrated solution entering the low temperature heat exchanger, and reduces the capacity of the heat exchanger. In addition, when there is a large amount of outflow from the low temperature regenerator, there is a concentrated solution that flows directly from the low temperature regenerator side to the absorber side, raising the temperature of the absorber side concentrated solution and improving the capacity of the low temperature heat exchanger. It will decrease. With this method, even if the capacity is increased in order to improve the performance of the low-temperature heat exchanger, the effect cannot be exhibited sufficiently, and in some cases, the performance may be reduced.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems, and to provide an economical multi-effect absorption refrigerator that has little fluctuation in refrigeration capacity, does not deteriorate the performance of a low-temperature heat exchanger, has good thermal efficiency, and is economical.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, the regenerator has at least a high temperature regenerator and a low temperature regenerator, one dilute solution pump for sending a dilute wave from the absorber, and the low temperature regenerator to the low temperature heat exchanger. In a multi-effect absorption refrigerator having a concentrated solution pump provided in a concentrated solution flow path connecting the inlets of the liquids, the diluted solution pump and the concentrated solution pump are provided with a rotation speed controller for adjusting the rotation speed, and a high temperature regenerator A sensor for detecting the pressure of the solution is provided, and according to the increase or decrease of the detected value of the pressure of the sensor, the rotational speed of the dilute solution pump and the concentrate solution pump is respectively increased or decreased to adjust the solution circulation amount .
[0007]
The absorption refrigerator can be a double or triple effect absorption refrigerator in which the regenerator comprises a high temperature regenerator and a low temperature regenerator or a high temperature regenerator, a medium temperature regenerator, and a low temperature regenerator. Instead of directly detecting the pressure of the high temperature regenerator, the pressure detecting sensor can detect the differential pressure between the high temperature regenerator and the low temperature regenerator, the differential pressure between the high temperature regenerator and the medium temperature regenerator, or the high temperature regenerator. It is also possible to detect the pressure difference between the vacuum and the absorber, or a physical quantity related to the pressure, and also provide a liquid level sensor at the outlet of the low temperature regenerator to increase or decrease the frequency of the concentrated solution pump. It is also possible to have means for controlling the liquid level to be between the high and low levels of the sensor.
In addition, the rotation speed adjuster can be an inverter control device that adjusts the frequency of the pump power source, and both the dilute solution pump and the concentrated solution pump can be controlled by a single control device.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a multi-effect absorption refrigerator, a sensor for detecting the pressure of a high-temperature regenerator, a dilute solution pump for sending a dilute solution from the absorber to the high-temperature regenerator, and a concentrated solution channel provided from the low-temperature regenerator. The solution pump is provided with a rotation speed controller that adjusts the rotation speed. Based on a sensor that detects the pressure of the high temperature regenerator, the rotation speed of the dilute solution pump is adjusted and the low temperature regenerator The rotational speed of the concentrated solution pump provided in the flow path is adjusted.
In the multi-effect absorption refrigerator according to the present invention, based on the high temperature regenerator pressure that controls the solution outflow amount of the high temperature regenerator, the rotational speed of the dilute solution pump is set so that the solution inflow to the high temperature regenerator corresponds to the outflow amount. The amount of solution circulation in the entire cycle is governed by the high temperature regenerator pressure, and the concentrated solution outflow from the low temperature regenerator also increases or decreases in relation to the high temperature regenerator pressure.
Therefore, by adjusting the rotational speed of the concentrated solution pump based on the high temperature regenerator pressure, the concentrated solution pump can be continuously operated in accordance with the concentrated solution flow rate from the low temperature regenerator. Further, it is possible to prevent cavitation of the concentrated solution pump without bypassing the low-temperature heat exchanger.
[0009]
Next, the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic process diagram showing an example of the absorption refrigerator of the present invention, which is an example of double effect.
In FIG. 1, A is an absorber, GL is a low temperature regenerator, GH is a high temperature regenerator, C is a condenser, E is an evaporator, XL is a low temperature heat exchanger, XH is a high temperature heat exchanger, and P1 is a dilute solution pump. , P2 is a refrigerant pump, P3 is a concentrated solution pump, J is a J line, 1-9 are solution circuits, and 10-13 are refrigerant circuits.
Moreover, in order to control the dilute solution pump P1, the pressure sensor 20 and the regulator 21 are provided, and in order to control the concentrated solution pump P3, the adjuster 22 is provided, and a1-a4 shows a concentrated solution level.
[0010]
In the cooling operation of this apparatus, the dilute solution that has absorbed the refrigerant passes from the absorber A through the heated side of the low-temperature heat exchanger XL by the solution pump P1, and branches partially to the heated side of the high-temperature heat exchanger XH. And is introduced from the circuit 2 into the high-temperature regenerator GH. In the high temperature regenerator GH, the dilute solution is heated by a heating heat source, and the refrigerant is evaporated and concentrated. The concentrated concentrated solution passes through the circuit 3 and is heat-exchanged in the high temperature heat exchanger XH, and passes through the circuit 6 to the low temperature regenerator. Merge with concentrated solution from GL in circuit 5. On the other hand, the remaining portion of the dilute solution that has passed through the heated side of the low-temperature heat exchanger XL is introduced into the low-temperature regenerator GL from the circuit 4, and the low-temperature regenerator GL is heated and concentrated by the refrigerant vapor from the high-temperature regenerator GH. The concentrated solution pump P3 from the circuit 5 joins the concentrated solution that has passed through the heating side of the high-temperature heat exchanger XL, passes through the heating side of the low-temperature heat exchanger XL, and is introduced from the circuit 9 into the absorber A.
[0011]
The refrigerant gas generated in the high temperature regenerator GH passes through the refrigerant circuit 13, is used as a heat source for the low temperature regenerator GL, and is then introduced into the condenser C. In the condenser C, it is cooled and condensed by the cooling water together with the refrigerant gas from the low temperature regenerator GL, and enters the evaporator E from the circuit 12. In the evaporator E, the refrigerant is circulated through the

circuits

10 and 11 by the refrigerant pump P2 and evaporated. At that time, the heat of evaporation is taken from the cold water on the additional side, and the cold water is cooled and supplied to the cooling.
The evaporated refrigerant vapor is absorbed by the concentrated solution in the absorber A, becomes a diluted solution, and becomes a cycle that is circulated by the diluted solution pump P1.
The concentrated solution pump P3 guides the concentrated solution flow rate from the low temperature regenerator GL to the low temperature heat exchanger XL.
The dilute solution pump P1 and the concentrated solution pump P3 are controlled by the

regulators

21 and 22 based on the signal from the pressure sensor 20.
[0012]
a1 and a2 are the solution levels of the concentrated solution of the high temperature regenerator, where a1 is high and a2 is low. Further, a3 and a4 are solution levels of the concentrated solution of the low temperature regenerator, a3 indicates an overflow limit, and a4 indicates a cavity limit.
The overflow limit a3 indicates the limit at which the solution of the low temperature regenerator enters the condenser C or the operation of the J line (if the solution crystallizes in the low temperature heat exchanger XL, it returns to the absorber A through the J line). .
Specific control of solution circulation will be described with reference to FIGS.
In the case of a double effect absorption refrigerator using a LiBr / H ₂ O system as an absorbent / refrigerant, the pressure of each device is roughly as follows. Since the pressure fluctuates depending on the load state, cooling water temperature, etc., the pressure is shown with a width.
Evaporator, absorber: 5 to 10 mmHgA,
Condenser, low temperature regenerator: 20-50 mmHgA,
High temperature regenerator: 200 to 700 mmHgA,
[0013]
2 to 4 show the flow relationship corresponding to FIG. The case where 50% of the dilute solution circulation amount is supplied to the low temperature regenerator and the remaining 50% is supplied to the high temperature regenerator is illustrated.
FIG. 2 shows the relationship between the high temperature regenerator pressure and the dilute solution pump flow rate, and the amount of return from the high temperature regenerator to the low temperature regenerator side (the return capacity because the pressure difference is returned as the driving force).
To be precise, although the differential pressure between the high temperature regenerator and the low temperature regenerator flows as a driving force, the pressure on the low temperature regenerator side is small, and it can be considered based on the pressure of the high temperature regenerator. In the figure, two lines indicate a case where the low pressure regenerator side pressure is 20 mmHg (b) and a case where the pressure is 50 mmHg (c).
The concentrated solution flow rate from the high temperature regenerator is approximately 0.85 to 0.95 VGH with respect to the dilute solution flow rate VGH to the high temperature regenerator. Further, the flow rate of the concentrated solution returning to the absorber is about 0.85 to 0.95 VP with respect to the flow rate VP of the dilute solution pump.
[0014]
FIG. 3 shows the characteristics of the dilute solution pump and the locus during operation of the absorption refrigerator. In addition to the flow rate, the horizontal axis indicates the high-temperature regenerator pressure (average) in FIG. 2 corresponding to the pump flow rate in parentheses.
In this example, the frequency of the dilute solution pump is set based on Table 1 below. On the way, the distribution is proportional. More specifically, a liquid level sensor is provided at the outlet of the high-temperature regenerator, and when the liquid level reaches a high level a1, the frequency is decreased to reduce the pump feed amount, and the liquid level is recovered. When the value becomes low a2, the frequency is increased to increase the pump feed amount, and the liquid level is recovered.
[Table 1]

[0015]
FIG. 4 shows the characteristics of the concentrated solution pump and the locus during operation of the absorption refrigerator. The operation trajectory indicated by a broken line is an operable range in which the liquid level position in the pipe (height h in FIG. 1) on the low temperature regenerator side is a parameter, and indicates the ablation limit f of a4 and the overflow limit g of a3. Corresponding to the high-temperature regenerator pressure, the operating locus when the rotational speed of the concentrated solution pump is determined in Table 2 is indicated by a thick solid line d. The middle is proportional distribution.
[Table 2]

[0016]
The operable range is quite large, and operation is possible even if the frequency setting is rough to some extent. For example, when the concentrated solution pump is operated at the same power supply frequency as that of the diluted solution pump, a thick two-dot chain line e is obtained, and an inverter or the like can be shared. However, if a separate power source is used, there is an advantage that the operating point can be changed considerably freely by correcting the table.
A liquid level sensor is provided at the outlet of the low-temperature regenerator.When the liquid level becomes high, the frequency is increased to increase the pump feed amount.When the liquid level becomes low, the frequency is increased. It may be controlled to reduce the pump feed amount and to restore the liquid level so that the liquid level is between the sensors.
[0017]
FIGS. 5 to 7 show schematic process diagrams of another absorption refrigerator according to the present invention. FIGS. 5 and 6 show a double effect and FIG. 7 shows an example of a triple effect. All symbols have the same meaning as in FIG. In FIG. 5, the dilute solution is introduced from the circuit 2 through the heated side of the low temperature heat exchanger XL and the high temperature heat exchanger XH from the absorber A to the high temperature regenerator GH by the solution pump P1, and the concentrated concentrated solution is Heat is exchanged in the circuit 3 through the high-temperature heat exchanger XH, introduced from the circuit 4 to the low-temperature regenerator GL, concentrated, and then from the circuit 5 through the concentrated solution pump P3 through the heating side of the low-temperature heat exchanger XL. 9 is introduced into the absorber A. The rest is the same as in FIG.
[0018]
In FIG. 6, the dilute solution is branched from the absorber A through the solution pump P1, and partly passes through the heated side of the high-temperature heat exchanger XH and is introduced from the circuit 2 into the high-temperature regenerator GH to be concentrated and concentrated. The solution circuit 3 passes through the high-temperature heat exchanger XH heating side and is introduced into the absorber A from the circuit 6. On the other hand, the branched remainder passes through the heated side of the low-temperature heat exchanger XL, is introduced into the low-temperature regenerator GL and concentrated, and then the heated side of the low-temperature heat exchanger XL is transferred from the circuit 5 by the concentrated solution pump 3. And is introduced into the absorber A. Others are the same as in FIG.
FIG. 7 shows a triple effect. In FIG. 1, an intermediate temperature regenerator GM is arranged between the high temperature regenerator GH and the low temperature regenerator GL. Similarly, the heat exchanger also has an intermediate temperature heat exchanger XM between the high temperature and the low temperature. The dilute solution that has passed through the heated side of the intermediate temperature heat exchanger XM is branched, a part is introduced into the intermediate temperature regenerator, and the remaining portion is introduced into the heated side of the high temperature heat exchanger. Go.
Thus, also in the absorption refrigerator of FIGS. 5-7, there can exist an effect similar to FIG.
[0019]
【The invention's effect】
According to the present invention, as described above, in order to improve the efficiency of the refrigerator, the heat transfer area of the heat exchanger or the heat passage rate is improved, and the pressure loss (flow resistance) of the heat exchanger increases. However, by controlling the rotational speed of the concentrated solution pump, the concentrated solution from the low temperature regenerator can be continuously returned to the absorber, and stable operation is possible.
Further, there is no concentrated solution to be recirculated or bypassed in the low temperature heat exchanger, and the capacity of the low temperature heat exchanger can be utilized to the maximum.
[Brief description of the drawings]
FIG. 1 is a schematic process diagram showing an example of an absorption refrigerator according to the present invention.
2 is a graph showing the relationship between the high-temperature regenerator pressure and the flow rate in FIG.
FIG. 3 is a graph showing the dilute solution pump characteristics in FIG. 1;
4 is a graph showing the concentrated solution pump characteristics in FIG. 1. FIG.
FIG. 5 is a schematic process diagram showing another example of the double-effect absorption refrigerator of the present invention.
FIG. 6 is a schematic process diagram showing another example of the double-effect absorption refrigerator of the present invention.
FIG. 7 is a schematic process diagram showing an example of a triple effect absorption refrigerator according to the present invention.
[Explanation of symbols]
A: Absorber, E: Evaporator, C: Condenser, GH: High temperature regenerator, GM: Medium temperature regenerator, GL: Low temperature regenerator, XH: High temperature heat exchanger, XM: Medium temperature heat exchanger, XL: Low temperature Heat exchanger, P1: dilute solution pump, P2: refrigerant pump, P3: concentrated solution pump, J: J line, 1-9: solution circuit, 10-13: refrigerant circuit, 18: cooling water, 19: cold water, 20 : Pressure sensor, 21, 22: Rotational speed controller, a1 to a4: Liquid level

Claims

The regenerator has at least a high-temperature regenerator and a low-temperature regenerator, and a concentrated solution provided in a concentrated solution flow path connecting one dilute solution pump for sending a dilute solution from the absorber to the inlet of the low-temperature heat exchanger in multiple effect absorption refrigerating machine and a pump, provided with a rotational speed regulator for adjusting the rotational speed to the rare solution pump and the concentrated solution pump, provided with a sensor for detecting the pressure of the high-temperature regenerator, the pressure of the sensor A multi-effect absorption refrigerator that adjusts the amount of solution circulation by increasing or decreasing the rotational speeds of the dilute solution pump and the concentrated solution pump according to the increase or decrease of the detected value .

A multi-effect absorption refrigerator characterized in that the regenerator has a double or triple effect consisting of a high temperature regenerator and a low temperature regenerator or a high temperature regenerator, a medium temperature regenerator and a low temperature regenerator.

The sensor for detecting the pressure of the high temperature regenerator is a differential pressure between the high temperature regenerator and the low temperature regenerator, a differential pressure between the high temperature regenerator and the medium temperature regenerator, or between the high temperature regenerator and the absorber. The multi-effect absorption refrigerator according to claim 2, wherein the differential effect or a physical quantity related to the pressure is detected.

A liquid level sensor is provided at the outlet of the low-temperature regenerator, and means for controlling the liquid level to be between the high level and low level of the sensor by increasing or decreasing the frequency of the concentrated solution pump. The multi-effect absorption refrigerator according to claim 1, 2, or 3.